Saturday, December 25, 2010

introduction of simulation to the medical students

Ad hoc teams is different from permanent ones since they cannot be trained to work together. The team is formed in short period where the members may not know each other. Members need "portable skills" in many areas below in order to improve safety, efficiency and morale

Crisis resource management in medicine aims to develop the same set of portable skills, and includes teamwork as a component with elements of leadership, cooperate, coordinate and communicate.

Components of teaching simulation for undergraduates:

1. Trained and committed lecturers with exposure to medical simulation

2. Objectives and learning outcome

  • Introduction to experiential learning
  • ensure all students understand the limitation of the manikin (e.g. unable to show pallor, cyanosis), have an open mind during the session and to treat manikin as they treat their own patients. At the same time don't forget to interact. Allow them familiar with the manikins

3. Have the scenario, which is ususally specific to the environment (icu, operation theatre, ward, emergency room)

  • in the end, give the management pathway (in this case may be appropriate to give principles and references
  • show their basic clinical skills: accumulation of data from clinical observation, monitors, environment, equipment and lab/radiology and able to analyse them in looking for possible problems

4. The key elements are

  • introduction to critical thinking
  • Learn how to communicate effectively -verbally and non verbally
  • introduction to crisis management principle
  • team work

5. Debriefing

Thursday, December 23, 2010

Oh December!

The title above has nothing to do with the content of this account. For a long time, I am struggling to teach the icu topics to 4th year medical students. It is only two tutorial and very minimal exposure to the units while doing their anaesthesiology two weeks rotation. Finally I have finished writing the chapter, well not quite writing it but the contents are appropriate for them to understand about icu. The second one is to introduce the concept of problem orientated systematic approach and this one is really challenging!

Well, I have been away for sometimes and I think the simulation skills classes for the students are a little bit out. I am working on this since I think I have the knowledge in this area.

I am going to revise the keys in crisis resource management and may revisit the whole thing in a formal manner.

  1. Know your environment
  2. Anticipate and plan
  3. Call for help early
  4. Take a leadership role
  5. Communicate effectively
  6. Allocate attention wisely, Use all available information
  7. Distribute the workload and utilise all available resources

Monday, December 13, 2010

neutropenic sepsis

It has been a while since I am back for good. Sadly to say that I deferred my clinical exam to next year. Everything happenned for a reason and I had a fruitful break from my daily life. Here I come, fresh and vibrant!!
I just feel like writing something, it is not an update..just to write something that I saw on my table. It is a brief overview of neutropenic sepsis.
Don't you know that about 80% of infections in the neutropenic patient arise from endegenous flora. Bacteria pathogens are the most commonly isolated, in particular:
E.Coli, Pseudomonas, staph aureus, coagulase neg staph, pneumonococcus and other streptococci, Enterococci, enterobacter, Klebsiella and clostridium.
Please remember other pathogens which are of significant important such as aspergillus, candida species and viruses (HSV, VZV,CMV)

Looking for source of infection and source control are the mainstay of management. Infectious focus could only identified in only 30% of patients, therefore a thorough, structured and careful clinical examination is required. Specific infections that must be looked for include mucositis, catheter related infection, pneumonia, skin lesions, perianal abscess, sinusitis, dental abscess and abdominal pathology. A full septic screen is required and this include CXR. There shouldn't be a delay in administering antibiotic or antimicrobial therapy.

Source control is critical. Removal of CVC is required whenever there are clinical signs of CRBSI or suspected organisms are cultured. In septic shock (with hypotension and organ failure), empirical removal of CVC is strongly indicated.

Antimicrobial therapy: Delay in antibiotic therapy is directly correlated with mortality. Empiric antibiotic therapy is indicated for all patients with neutrophil count less than 0.5 or temperature more than 38C. Initial therapy is usually betalactam with antipseudomonal activity. Vancomycin is added if the patient is in shock, MRSA colonised, or has clinical evidence of mucositis or a catheter related infection. Initial antifungal therapy is indicated for bone marrow transplant recipients and for other patients if the febrile neutropenia persists despite 5 days of broad spectrum antibiotic therapy.

G-CSF are generally used for critically ill patients with post chemotherapy neutropenia. G-CSF has been shown to reduce the duration of neutropenia but not influence mortality in a broad population of neutropenic patients, and evidence is lacking for ICU patients. Usually its used is considered for patients with organ failure.

Thursday, June 17, 2010

My Brisbane Stint

I am not sure what to write as the title of this post. I don't like serious blogging for many reasons...First, I am not a fast typist at all and writing could really consume my precious time. Then, I am never been a good writer neither in Malay nor English. This morning I feel like writing something, since my brissy stint is reaching its end. Towards the end of my shift this morning, my colleague Andrew congratulated me for successfully finishing my 7 days of night shift and asking me about my plan. I have told him that I am coming back tomorrow for a meeting with Prof regarding my research project for my sabbatical leave and the CICM training. It is on procalcitonin and I might get Yoshiro to give me a hand. I will try to get someone later to help me in data analysis from this unit at RBWH. Then Andrew asked me when am I leaving to Malaysia. After some explanation, which include a brief period of reporting duty and then coming back to complete my contract, meeting all of supervisors of training, etc etc, his comment was "Why is life is getting more complicated". Absolutely true mate.. That made me ponder, on the way back home I have been thinking a lot about my decision in coming to Brisbane, completing this exam and cicm training. I realised that, It is a very valuable experience indeed. I am happy that in my life I have met many people from different countries, different background, different life experience and at the same time making new friends everyday. I don't mind of being international and feel contented with this achievement. I don't envy those people at home whom are being promoted and achieved something without going through the long winding road that I have been through now. I don't envy them at all.. I am glad that I went thru the challenge and being accepted here.

1. After all preparations, finally I managed to register with the QMB. Yes, a lot of money and time spent and 2008 was my difficult year. It is not midlife crisis but it involves family, career and ambition. Finally on the 4th October 2008, I flew to Brisbane accompanied by my wife. Quite impressive since the hospital provided me with accommodation for 2 weeks. I started at TPCH. I think everything happenned for a reason..I was not prepared to sit for the exam then and this decision brought me to another phase of life here, i.e. RBWH

2. Life in RBWH is not as I expected as well. I struggled to study for my exam. Well, exam ...I think I was left alone and towards the end I was lef with no support...Praise to God that I passed the theory and proceed to viva and clinical exams. The fellowship is considered as high standard and to keep on par with the knowledge I compromised on my sleep substantially. The surmounted pressure in many aspects, draining me both mentally and physically. I just get exhausted and actually pushing myself very hard. Sometimes, I just don't have any more courage to go on.....

3. This bring me to another phase, a short October stint which will be negotiated. Anyway I hope I will stay focus on the exam and keep in tract as for the preparation.. I worked hard till the last day of my stay and finally also completed my assessment form. The October phase was postponed due to unavoidable personal reasons. It is a blessing in disguise

4. Wish me luck and my sincere heartiest appreciation to all my mates and wife who are giving their endless support. The most important is the journey and the knowledge gained.


Sunday, May 2, 2010

'This is where the money is'

This where the money is..often being quoted during the practice clinical cases
--> actually the hotcases are like the extension of the written exam questions where we have to show clinical skills to elicit important findings. 'Go directly to where the money is' meaning that we have to direct our clinical examination and clinical findings to be able to formulate answer to the specific tasks given. Usually the questions consists of at least two parts and must remember the questions very well. Don't forget to answer all parts of the questions (the same rule for written)


Cases

1. ARDS
CAP : include the management of CAP, antibiotics and if the patient in shock
-always remember the specific treatment and general management of the patients
-in any clinical management, firstly we have to get the diagnosis and must have few differential diagnosis.

2. VAP
-definition
-possible organisms
-management

3. CRBSI

-definition
-management

4. management of severe TBI with high intracranial pressure
-regarding prognosis
-family meeting
-rescue therapy
Thiopentone:
--------------
Thiopental has a long Context Sensitive Half Time (CSHT), meaning infusions saturate peripheral compartments (fat, muscle etc). When the infusion is stopped, the drug re-distributes from the peripheral tissues back into the blood, prolonging the effect.
Thiopental also exhibits zero order kinetics at higher doses. The rate of elimination becomes constant.
Contraindications:
1. Acute intermittent porphyria
2. Barbiturate allergy
3. Patients with a low circulating blood volume, such as after haemorrhage, are prone to severe hypotension with thiopentone.
4. Patients with cardiac disease (particularly those with stenotic heart valve lesions) are at risk from the cardiovascular depressant effects of thiopentone. The drug must be carefully titrated against effect.
5. Patients with partial airway obstruction should not be given an intravenous anaesthetic agent in case total airway obstruction develops.
6. In severe asthma it is thought that thiopentone may occasionally cause bronchospasm.
Metabolism. For many years it was thought that the short duration of action of thiopentone was due to its rapid metabolism. It is now known that thiopentone is metabolised quite slowly, and the rapid recovery is due to redistribution of the drug firstly into muscle and skin, and later into body fat stores.
Thiopentone is metabolised in the liver; less than 1% of the drug appears in the urine unchanged

Thursday, April 29, 2010

Five Helpful Tips To Get Smart

This is what I have found today:


1. Read aloud
This apparently lights up the brain like switchboard. Just a minute a day will benefit your brain function.

2. Get word-savvy
Playing board games reduces your risk of dementia, in particular Scrabble. In fact building a vocabulary is one of the best things you can do for your brain. So every day look up a new word in the dictionary, say it out loud, and then try to use it in a sentence, either in your mind or in a conversation.

3. Eat and drink to stay sharp
Blueberries, turmeric, soy milk and avocados are all great brain food, along with purple grape juice as the polyphenals it contains slows down brain ageing.

4. Routine swap
You may hit the gym for aerobics, but you should also be exercising your brain daily. These are easy, and mostly involve changing your routine to engage your brain more deeply from day to day. Try brushing your teeth or using the computer mouse with the opposite hand to the one you usually use, or simply take a different route to work once a week.

5. Walk
Not only does it increase blood circulation, oxygen and glucose to the brain, but walking just 20 minutes a day can decrease your risk of memory loss and stroke and improve learning ability, concentration and abstract reasoning.

Communication station

Important part of the exam and candidate must pass (preferably)--is the communication station

Remember that you must show empathy and discuss the meeting with primary team


Suggested interview structure:

Introduction
Introduce yourself and staff members
Determine names and relationships of family members or surgeon
Explain why you are meeting (state the goal of the meeting)

Gather information
Ask what the family members know about the medical situation
Ask what they have been told by others
Ask what thy think about the future prospects
Ask about the patient's function, values, fears and wishes
Ask who feel they best represent the patient
Ensure all the important decision makers are present (or involved)

Give information
Explain the current medical situation
Explain the expected prognosis
Explain any planned interventions/investigations
Explain what you think the future progression will be
Take care to use clear, non-medical language
Avoid ambiguity wherever possible

Check understanding
Check that everyone understands what you have just told them

Agree a plan
Ensure you have clear outcomes from the meeting i.e. ou have 'negotioted to a conclusion'
Confirm everyone understands and agree with the plan

Plan for next meeting
If a clear and final outcome has not been agreed, it is important to plan for another meeting before the family leaves

6 steps to effective end-of-life communication:

-Explain
-Explore
-Options
-Advise
-Agree
-Communicate

Wednesday, April 28, 2010

What more do I have to say?




I think this song is beautiful and I want to post the lyrics here. Anyway, regardless of how my special one may look at me ----I still want to wish her a very very Happy Birthday.

Only ArRahman knows what are the tangible or non tangible contributions or interpretation of my commitments in our lives.
“One is loved because one is loved. No reason is needed for loving.”
Yeah, you don't agree with this but
“Why do we have to listen to our hearts?" "Because, wherever your heart is, that is where you'll find your treasure.”

Please enjoy every single day that blessed by Him on us;
"You can become blind by seeing each day as a similar one. Each day is a different one, each day brings a miracle of its own. It's just a matter of paying attention to this miracle."


This song is one of my favourites, I am not disheartened if you disagree.....

"Both Sides Now"

Rows and flows of angel hair and ice cream castles in the air
And feather canyons ev'rywhere, I've looked at clouds that way
But now they only block the sun, they rain and snow on ev'ryone
So many things I would have done but clouds got in my way

I've looked at clouds from both sides now
From up and down, and still somehow
It's cloud illusions I recall
I really don't know clouds at all

Moons and Junes and Ferris wheels, the dizzy dancing way you feel
As ev'ry fairy tale comes real, I've looked at love that way
But now it's just another show, you leave 'em laughing when you go
And if you care, don't let them know don't give yourself away

I've looked at love from both sides now
From give and take, and still somehow
It's love's illusions I recall
I really don't know love at all

Tears and fears and feeling proud, to say "I love you" right out loud
Dreams and schemes and circus crowds, I've looked at life that way
But now old friends are acting strange, they shake their heads, they say I've changed
Well something's lost, but something's gained in living ev'ry day

I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions I recall
I really don't know life at all

I've looked at life from both sides now
From up and down, and still somehow
It's life's illusions I recall,
I really don't know life at all

Thursday, March 11, 2010

Ethical question as SAQ

Question:

A 49 year old with endstage motor neuron disease takes a deliberate, lethal, benzodiazepine overdose. As he becomes sleepy, he tells his wife what he has done and asks that he stays with him as he dies. They had discussed his wish to commit suicide before, rather than suffer the indignity and distress of respiratory failure in hospital. He has an advanced directive not to be ventilated in the event of respiratory failure. His power of attorney is a barrister who is also a close friend of both the patient and his wife.

She panics however, as he becomes unconscious and calls an ambulance. Finding him unconscious and in drug induced respiratory failure, the ambulance intubates and ventilates him and delivers him to the hospital emergency department.
You are the intensive care specialist on call and are asked to take him to ICU for ongoing care.
Outline the principles of the management.
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
answer
complex situation:
5 areas need to be considered:
-the patient's autonomy: which is not acessible since he is unconscious due to OD
-nature of motor neurone disease: irreversible
-advanced directive for mechanical ventilation: clarifiy this, but OD has not been described
-the nature of power of attorney: health or financial: discuss this with that person
-support to his wife: reassure
-deliberate overdose: effect which may be reversible, but the secondary effect of possible ischaemic brain due to hypoxaemia?

Bring to ICU while those being resolved.

Monday, February 8, 2010

Carbicarb, Na bicarbonate, THAM



Compare and contrast the pharmacology of carbicarb, Sodium bicarbonate and THAM.


Carbicarb:
Another potential and perhaps more effective alternative to Na bicarbonate is an equimolar mixture of sodium carbonate (Na2CO3) and sodium bicarbonate called "Carbicarb". Sodium carbonate in the mixture reacts with carbonic acid (H2CO3) to generate bicarbonate via the following reaction:

CO3(2-) + H2CO3 = 2 HCO3-

Thus, the carbonate component of Carbicarb consumes H2CO3 (or CO2) while the HCO3 component and the newly generated HCO3 will form CO2 when protons are buffered. Consequently, the total amount of CO2 which is generated is two-thirds the amount that would be generated by an equimolar amount of HCO3 alone. The mixture of sodium carbonate and Na bicarbonate is utilized instead of sodium carbonate alone because a solution of pure sodium carbonate is too caustic to be intravenously infused. The risks of hypertonicity and hypervolemia are similar to those of sodium bicarbonate.
Carbicarb has been evaluated in animals, with inconsistent benefit compared with Na bicarbonate. One human study of 36 surgical patients with metabolic acidosis compared the effects of sodium bicarbonate with Carbicarb. No benefit was observed.
 
Na Bicarbonate

Bicarbonate is an anion and cannot be given alone. Its therapeutic use is as Na bicarbonate. An 8.4% solution is a molar solution (i.e. it contains 1 mmol of HCO3- per ml) and is the concentration clinically available in Malaysia. This solution is very hypertonic (osmolality is 2,000 mOsm/kg). 
The main use of alkali therapy include to counteract the extracellular acidemia and thus avoiding the side effects of acidosis, in emergency treatment of hyperkalaemia and to promote alkaline diuresis.
 
The severity of the undesirable effects will depend on the amount of bicarbonate used:
  • hypernatraemia
  • hyperosmolality
  • volume overload
  • rebound or ‘overshoot’ alkalosis
  • hypokalaemia
  • impaired oxygen unloading due to left shift of the oxyhaemoglobin dissociation curve
  • acceleration of lactate production by removal of acidotic inhibition of glycolysis
  • CSF acidosis
  • hypercapnia
  • can cause paradoxical acidosis in the presence of a low output

  • THAM (tris-hydroxymethyl aminomethane)
     
    THAM  is an amino alcohol which buffers protons by virtue of its amine (NH2) moiety via the following reactions:
     
    THAM-NH2 + H+ = THAM-NH3+

    Unlike bicarbonate which generates CO2, THAM consumes CO2:

    THAM-NH2 + H2O + CO2 = THAM-NH3+ + HCO3-

    The urinary clearance of protonated THAM salts is slightly greater than urinary clearance of creatinine. To the extent THAM-NH3+ is excreted in the urine with chloride, this represents net acid excretion. However, if THAM-NH3+ is excreted with HCO3-, then no net acid excretion occurs. Thus, THAM can increase the buffering capacity of blood without generating CO2 but is less effective in anuric patients.
    Reported toxicities of THAM include hyperkalemia, hypoglycemia, extravasation related necrosis, hepatic dysfunction.and respiratory depression; the last complication may be due to the ability of THAM to rapidly increase the pH and decrease the PCO2 in the central nervous system. 
     
    THAM has been used to treat severe acidemia due to sepsis, permissive hypercapnia, diabetic ketoacidosis, renal tubular acidosis, gastroenteritis, and drug intoxications. However, THAM has not been evaluated in clinical trials involving patients with lactic acidosis. Thus, the efficacy and safety of THAM in such patients is unknown.


    Saturday, February 6, 2010

    Diagnosis of Brain Death

    The diagnostic algorithm has 3 sequential but interdependent steps:
    1. Preconditions
    2. Exclusions
    3. Clinical Tests

    1. Preconditions
    i. Apnoeic coma
    ii. Structural brain damage that is consistent with diagnosis of brain stem death
    iii. The underlying disorder must be established
    -evidende of sufficient intracranial pathology or a known cause of coma e.g. traumatic brain injury, intracerebral haemorrhage, hypoxic-ischaemic encephalopathy.

    Exclusions: reversible causes of coma must be excluded

    i. Alcohol and drug overdose
    ii. Effects of therapeutic depressant drugs: take liver and renal function into consideration
    iii. Residual action of NMB agents: ask whether Train of four stimulation has been performed to exclude neuromuscular paralysis.
    iv. Hypothermia (T<35c): The patient is normothermic (T more than 35C)
    v. Normotension: as a guide SBP more than 90 mmHg, MAP more than 60 mmHg in an adult
    vi. without severe metabolic, electrolyte or endocrine derangement
    vii. ability to adequately examine the brain stem reflexes
    viii. ability to perform apnoea testing

    Clinidal Tests:
    - Canial nerve examination
    i. Pupillary reflex -tests II and III
    ii. Corneal reflex: tests V and VII
    iii.Painful stimulus at 3 areas of V-tests V and VII
    iv. vestibulo-ocular reflex : III, VI and VIII --llook in both ears to check that the canals are not occluded and the tympanic membranes are intact. Ask an assistant to hold the eyeslids open for you and then inject 20ml of ice cold water into each ear canal in turn. Movement of the eyes towards the side of the stimulus is an intact vestibulo-ocular response.
    v. Gag and cough reflexes: IX and X -check under direct laryngoscopic vision. Check cough reflex using a tracheal suction catheter.

    Note:
    1. Apnoea tests
    -The apnoea test confirms the absence of spontaneous respiratory effort despite PaCO2 at level above the threshold for respiration.
    - may be difficult in cardioresp instability, spinal cord
    -ventilate with 100% oxygen. Passively oxygenate during the test either using a Mapleson C circuit attached to the endotracheal tube. If starting PaCO2 is normal, allow it to rise to 60mmHg (pH 7.3) or 20mmHg higher than the patient's baseline if this is elevated (e.g. COPD). The rate of PaCO2 during apnoea is approximately 3mmHg/min
    When assess the GCS, check response to voice before touching the patient. Response to pain should be tested by pressing on the supraorbital ridges (V), the temporomandibular joint (V) and a nail bed on each limb.
    2. The oculocephalic reflex (doll's eye) is not part of the Australian brain death testing requirements.

    Supplementary diagnostic techniques:
    recommended tests by ANZICS -
    1. Four vessels angiography -no blood flow above the carotid siphon in the anterior circulation and no blood flow above the foramen magnum in the posterior circulation
    2. Radionuclide imaging - Tcc-99 HMPAO scan demonstrating absent intracranial perfusion
    3. CT angiography: absent enhancement bilaterally of peripheral intracranial arteries and central veins at 60 seconds. There is less experience with this technique.


    e.g.

    1. Cranial nerves cannot be adequately tested-it must be possible to examine a least one ear and one eye

    2. High Cervical cord injury is present or suspected. (preclued apnoea test)
    3. Cardiorespiratory instability that precludes testing for apnoea. (severe hypoxic respiratory failure)
    4. Possible drugs or metaolic effect on coma that cannot be excluded.

    Thursday, February 4, 2010

    The use of steroids in ARDS

    Corticosteroids in ARDS

    Systemic corticosteroids have been studied extensively for use in ARDS. While they clearly have a role in situations when ARDS has been precipitated by a steroid-responsive process (eg, acute eosinophilic pneumonia), the value of steroids in most cases is uncertain.
    Empiric corticosteroids were widely used to treat ARDS in the 1970s and early 1980s. However, corticosteroid therapy became less frequent in the late 1980s after several studies found that corticosteroids had no benefit and may cause harm in patients with ARDS.

    The first clinical trial to report a beneficial effect of corticosteroids in ARDS was the one by Meduri et al in 1998. In a randomized, placebo controlled cross over single centre trial enrolling 24 patients corticosteroids were shown to improve lung injury score and reduce mortility.

    Subsequent studies focused on patients in the fibroproliferative phase of ARDS, occasionally referred to as persistent ARDS or late ARDS. The fibroproliferative phase is characterized by fever, purulent secretions, and new pulmonary infiltrates without evidence of infection. Evidence that corticosteroids can ameliorate pulmonary inflammation has provided an important rationale for continuing to study their use in the treatment of ARDS.

    A double-blind trial by the ARDS Network randomly assigned 180 patients with persistent ARDS to receive methylprednisolone or placebo for 21 days [NEJM 2006]. Persistent ARDS was defined as ongoing disease seven to 28 days after its onset. When the methylprednisolone and placebo groups were compared:

    1. There was no difference in 60-day mortality (29.2 versus 28.6 percent) or 180-day mortality (31.5 versus 31.9 percent).
    2. Among patients randomized 7 to 13 days after the onset of ARDS, methylprednisolone caused a nonstatistically significant reduction in 60-day mortality (27 versus 36 percent) and 180-day mortality (27 versus 39 percent).
    3. Among patients randomized more than 14 days after the onset of ARDS, methylprednisolone increased 60-day mortality (35 versus 8 percent) and 180-day mortality (44 versus 12 percent).
    4. methylprednisolone increased ventilator-free days, shock-free days, oxygenation, lung compliance, and blood pressure, but increased neuromuscular weakness and higher rate of reintubations.

    Other clinical trials addressed the possibility that corticosteroids might be effective when given early in ARDS. In a double-blind trial, patients with early ARDS (ie, ≤72 hours) were randomly assigned in a 2:1 ratio to receive corticosteroid therapy (n=63) or placebo (n=28) [Meduri Chest 2007]. Patients failing in one arm by day 7 to 9 underwent blinded crossover. Patients in the corticosteroid group were given methylprednisolone at 1 mg/kg per day for up to 28 days. Important features of this trial included vigilant surveillance for infection and avoidance of neuromuscular blockade.
    Corticosteroid therapy reduced the duration of mechanical ventilation, length of ICU stay, and ICU mortality (21 versus 43 percent). The results of this study should be considered provocative but not definitive given the trial's small size and imbalances in the treatment arms, which included a larger number of patients with catecholamine-dependent shock in the placebo group.

    Several meta-analyses and reviews offer conflicting perspectives regarding corticosteroid treatment for ARDS.

    Points of debate include when to begin steroids, how long to give them, whether they should be tapered, and how to interpret subgroup analyses in published trials. Although some data suggest possible survival advantages when given early, particularly before two weeks have elapsed, ongoing controversy dictates the need for more research before definitive recommendations regarding corticosteroids can be made.

    Consequently corticosteroids now do not form part of the therapeutic armamentarium for ARDS.

    Wednesday, February 3, 2010

    Five Short Answer Questions

    Five SAQs

    1. A patient passed 100mls of heavily bloodstained urine after suffering severe pelvic injury. How will you manage this problem?
    --comment: in answering this question take note that the main clue is SEVERE pelvic injury. This patient is suffering from significant impact and also other injuries. The trauma care and resuscitation according to ATLS apply.

    2. What is the lupus anticoagulant? What is its relevance to ICU practice?
    ----interesting question

    3. Critically evaluate the role of percutaneous tracheostomy in the ICU.


    A. Bedside percutaneous tracheostomy has now become an alternative to operative surgical tracheostomy:

    -requires less time to perform

    -less expensive

    -typically performed sooner (OR doesn't have to be scheduled)

    Complications may be less frequent with percutaneous tracheostomy than surgical tracheostomy. Results of a study of 46 patients (CCM 1991), when compared to ST: PT is performed in shorter time and significantly less haemorrhage, stomal infection, pneumothorax, all pre-decannulation adverse events, pre decannulation problems per procedure, tracheal stenosis and cosmetic deformity.

    In a metaanalysis of 17 randomised, controlled trials (1212 patients), percutaneous tracheostomy decreased wound infections compared to both surgical tracheostomy done in the OR and ICU. (Critical Care 2006)

    Percutaneous tracheostomy also decreased bleeding and mortality when compared to surgical tracheostomy performed in OR only.

    The second metaanalysis showed perioperative complications (including death, serious cardiorespiratory events, and minor complications) were rare but more common with percutaneous tracheostomy. In contrast minor postoperative complications were more common among patients receiving surgical tracheostomy. (CCM 1999)

    The different outcomes of the two meta analysis may reflect the different techniques used to perform PT.

    -the first meta-analysis included only studies that used percutaneous dilational tracheostomy. In contrast the second meta-analysis included studies of PT performed using a variety of techniques.

    -A recent RC study showed no difference in long term (median 20 m0nth) follow up.(CCM 2006)

    -Disadvantages of PT include an increased risk of anterior tracheal injury and posterior tracheal wall perforation.

    Taken together, the data suggest Percutaneous dilational tracheostomy offers numerous advantages compared to surgical tracheostomy.
    The benifit of PT may be substantially less depending on the technique employed.

    4. An audit of central venous catheters (CVC) in your ICU shows sepsis related rate of 30% . Outline what you will do?
    ----This is an audit question

    5. Critically evaluate the use of plasma troponin in the critically ill patient.
    ---is a critically evaluate question
    at the end of the debate must include ---in my opinion or in my practice....

    Tuesday, February 2, 2010

    arterial blood supply to the spinal cord


    Liver Cirrhosis


    Cirrhosis of the liver has a number of different causes:


    1. Alcohol

    The development of cirrhosis depends upon the amount and regularity of alcohol intake. Chronic, high levels of alcohol consumption injure liver cells. Thirty percent of individuals who drink daily at least eight to sixteen ounces of hard liquor or the equivalent for fifteen or more years will develop cirrhosis. Alcohol causes a range of liver diseases; from simple and uncomplicated fatty liver (steatosis), to the more serious fatty liver with inflammation (steatohepatitis or alcoholic hepatitis), to cirrhosis.


    2. Nonalcoholic fatty liver disease (NAFLD)

    NAFLD refers to a wide spectrum of liver diseases that, like alcoholic liver disease, ranges from simple steatosis, to nonalcoholic steatohepatitis (NASH), to cirrhosis. All stages of NAFLD have in common the accumulation of fat in liver cells. The term nonalcoholic is used because NAFLD occurs in individuals who do not consume excessive amounts of alcohol, yet, in many respects, the microscopic picture of NAFLD is similar to what can be seen in liver disease that is due to excessive alcohol. NAFLD is associated with a condition called insulin resistance, which, in turn, is associated with the metabolic syndrome and diabetes mellitus type 2. Obesity is the most important cause of insulin resistance, metabolic syndrome, and type 2 diabetes. NAFLD is the most common liver disease in the United States and is responsible for 24% of all liver disease. In fact, the number of livers that are transplanted for NAFLD-related cirrhosis is on the rise. Public health officials are worried that the current epidemic of obesity will dramatically increase the development of NAFLD and cirrhosis in the population.


    3. Cryptogenic cirrhosis (cirrhosis due to unidentified causes)

    is a common reason for liver transplantation. It is termed cryptogenic cirrhosis because for many years doctors have been unable to explain why a proportion of patients developed cirrhosis. Doctors now believe that cryptogenic cirrhosis is due to NASH (nonalcoholic steatohepatitis) caused by long standing obesity, type 2 diabetes, and insulin resistance. The fat in the liver of patients with NASH is believed to disappear with the onset of cirrhosis, and this has made it difficult for doctors to make the connection between NASH and cryptogenic cirrhosis for a long time. One important clue that NASH leads to cryptogenic cirrhosis is the finding of a high occurrence of NASH in the new livers of patients undergoing liver transplant for cryptogenic cirrhosis. Finally, a study from France suggests that patients with NASH have a similar risk of developing cirrhosis as patients with long standing infection with hepatitis C virus. (See discussion that follows.) However, the progression to cirrhosis from NASH is thought to be slow and the diagnosis of cirrhosis typically is made in patients in their sixties.


    4. Chronic viral hepatitis

    is a condition where hepatitis B or hepatitis C virus infects the liver for years. Most patients with viral hepatitis will not develop chronic hepatitis and cirrhosis. For example, the majority of patients infected with hepatitis A recover completely within weeks, without developing chronic infection. In contrast, some patients infected with hepatitis B virus and most patients infected with hepatitis C virus develop chronic hepatitis, which, in turn, causes progressive liver damage and leads to cirrhosis, and, sometimes, liver cancers.


    5. Inherited (genetic) disorders

    result in the accumulation of toxic substances in the liver which lead to tissue damage and cirrhosis. Examples include the abnormal accumulation of iron (hemochromatosis) or copper (Wilson's disease). In hemochromatosis, patients inherit a tendency to absorb an excessive amount of iron from food. Over time, iron accumulation in different organs throughout the body causes cirrhosis, arthritis, heart muscle damage leading to heart failure, and testicular dysfunction causing loss of sexual drive. Treatment is aimed at preventing damage to organs by removing iron from the body through bloodletting (removing blood). In Wilson disease, there is an inherited abnormality in one of the proteins that controls copper in the body. Over time, copper accumulates in the liver, eyes, and brain. Cirrhosis, tremor, psychiatric disturbances and other neurological difficulties occur if the condition is not treated early. Treatment is with oral medication that increases the amount of copper that is eliminated from the body in the urine.

    6. Primary biliary cirrhosis (PBC)
    is a liver disease caused by an abnormality of the immune system that is found predominantly in women. The abnormal immunity in PBC causes chronic inflammation and destruction of the small bile ducts within the liver. The bile ducts are passages within the liver through which bile travels to the intestine. Bile is a fluid produced by the liver that contains substances required for digestion and absorption of fat in the intestine, as well as other compounds that are waste products, such as the pigment bilirubin. (Bilirubin is produced by the breakdown of hemoglobin from old red blood cells.). Along with the gallbladder, the bile ducts make up the biliary tract. In PBC, the destruction of the small bile ducts blocks the normal flow of bile into the intestine. As the inflammation continues to destroy more of the bile ducts, it also spreads to destroy nearby liver cells. As the destruction of the hepatocytes proceeds, scar tissue (fibrosis) forms and spreads throughout the areas of destruction. The combined effects of progressive inflammation, scarring, and the toxic effects of accumulating waste products culminates in cirrhosis.


    7. Primary sclerosing cholangitis (PSC)

    is an uncommon disease found frequently in patients with ulcerative colitis . In PSC, the large bile ducts outside of the liver become inflamed, narrowed, and obstructed. Obstruction to the flow of bile leads to infections of the bile ducts and jaundice and eventually causes cirrhosis. In some patients, injury to the bile ducts (usually as a result of surgery) also can cause obstruction and cirrhosis of the liver.


    8. Autoimmune hepatitis

    is a liver disease caused by an abnormality of the immune system that is found more commonly in women. The abnormal immune activity in autoimmune hepatitis causes progressive inflammation and destruction of liver cells (hepatocytes), leading ultimately to cirrhosis.


    9. Infants can be born without bile ducts (biliary atresia) and ultimately develop cirrhosis. Other infants are born lacking vital enzymes for controlling sugars that leads to the accumulation of sugars and cirrhosis. On rare occasions, the absence of a specific enzyme can cause cirrhosis and scarring of the lung (alpha 1 antitrypsin deficiency).


    10. Less common causes of cirrhosis include unusual reactions to some drugs and prolonged exposure to toxins, as well as chronic heart failure (cardiac cirrhosis). In certain parts of the world (particularly Northern Africa), infection of the liver with a parasite (schistosomiasis) is the most common cause of liver disease and cirrhosis.

    Spinal Cord Trauma



    American Spinal Injury Association (ASIA) Grading Scale for Spinal Cord Injury

    A = No motor or sensory function preserved
    B = Sensory but no motor function preserved
    C = Nonuseful motor function preserved (less than antigravity strength)
    D = Motor function preserved but weak
    E = Normal motor and sensory function

    Neurology Injury:

    1. Complete Spinal Cord Injury (SCI)
    2. Incomplete SCI
    3. Specific Incomplete SCI syndromes:
    a. Central Cord Syndrome
    b. Brown-Sequard syndrome
    c. Anterior Cord Syndrome
    d. Conus medullaris Syndrome
    .
    The Effects of Spinal Cord Injury.
    The exact effects of a spinal cord injury vary according to the type and level injury, and can be organized into two types:

    Complete SCI
    There is no function below the level of the injury. Voluntary movement is impossible and physical sensation is impossible. Complete injuries are always bilateral, that is, both sides of the body are affected equally.

    A person with an incomplete injury retains some sensation below the level of the injury. Incomplete injuries are variable, and a person with such an injury may be able to move one limb more than another, may be able to feel parts of the body that cannot be moved, or may have more functioning on one side of the body than the other. In addition to a loss of sensation and motor function below the point of injury, individuals with spinal cord injuries will often experience other changes.Bowel and bladder function is associated with the sacral region of the spine, so it is very common to experience dysfunction of the bowel and bladder. Sexual function is also associated with the sacral region, and is often affected. Injuries very high on the spinal cord (C-1, C-2) will often result in a loss of many involuntary functions, such as breathing, necessitating mechanical ventilators or phrenic nerve pacing. Other effects of spinal cord injury can include an inability to regulate heart rate (and therefore blood pressure), reduced control of body temperature, inability to sweat below the level of injury, and chronic pain and also incontinence. Physical therapy and orthopedic instruments (e.g., wheelchairs, standing frames) are often necessary, depending on the location of the injury.The Location of the InjuryKnowing the exact level of the injury on the spinal cord is important when predicting what parts of the body might be affected by paralysis and loss of function.Below is a list of typical effects of spinal cord injury by location (refer to the spinal cord map to the right). Please keep in mind that the prognosis of complete injuries are predictable, incomplete injuries are very variable and may differ form the descriptions below.Cervical injuriesCervical (neck) injuries usually result in full or partial tetraplegia. Depending on the exact location of the injury, one with a spinal cord injury at the cervical may retain some amount of function as detailed below, but are otherwise completely paralyzed.

    C3 vertebrae and above: Typically lose diaphragm function and require a ventilator to breathe.
    C4: May have some use of biceps and shoulders, but weaker.
    C5: May retain the use of shoulders and biceps, but not of the wrists or hands.
    C6: Generally retain some wrist control, but no hand function.
    C7 and T1: Can usually straighten their arms but still may have dexterity problems with the hand and fingers. C7 is the level for functional independence. Thoracic injuriesInjuries at the thoracic level and below result in paraplegia. The hands, arms, head, and breathing are usually not affected.

    T1 to T8 : Most often have control of the hands, but lack control of the abdominal muscles so control of the trunk is difficult or impossible. Effects are less severe the lower the injury.

    T9 to T12 : Allows good trunk and abdominal muscle control, and sitting balance is very good. Lumbar and Sacral injuriesThe effect of injuries to the lumbar or sacral region of the spinal canal is decreased control of the legs and hips, and anus.
    Central cord syndrome (picture 1)
    is a form of incomplete spinal cord injury characterized by impairment in the arms and hands and, to a lesser extent, in the legs. This is also referred to as inverse paraplegia, because the hands and arms are paralyzed while the legs and lower extremities work correctly.Most often the damage is to the cervical or upper thoracic regions of the spinal cord, and characterized by weakness in the arms with relative sparing of the legs with variable sensory loss.This condition is associated with ischemia, hemorrhage, or necrosis involving the central portions of the spinal cord (the large nerve fibers that carry information directly from the cerebral cortex). Corticospinal fibers destined for the legs are spared due to their more external location in the spinal cord.This clinical pattern may emerge during recovery from spinal shock due to prolonged swelling around or near the vertebrae, causing pressures on the cord. The symptoms may be transient or permanent.
    Anterior Cord Syndrome (picture 2)
    is also an incomplete spinal cord injury. Below the injury, motor function, pain sensation, and temperature sensation is lost; touch, propioception (sense of position in space), and vibration sense remain intact. Posterior Cord Syndrome (not pictured) can also occur, but is very rare.
    Brown-Sequard Syndrome (picture 3)
    usually occurs when the spinal cord is hemisectioned or injured on the lateral side. On the ipsilateral side of the injury (same side), there is a loss of motor function, propioception, vibration, and deep touch. Contralaterally (opposite side of injury), there is a loss of pain, temperature, and light touch sensations.

    Variceal Bleeding

    -Variceal bleeding is the most common lethal complication of cirrhosis. Acute bleeding episodes carry 20% mortality at 6 weeks.
    -Mortality related to haemorrhage, liver decompensation, aspiration, hepatic encephalopathy, HRS, septicaemia and alcohol withdrawal.
    -Varices are present in 50% of patients with cirrhosis and 85% of Child-Pugh C patients.

    -Portal Hypertension -----> Collateral circulation to decompress pressure, junctions of squamous and columnar mucosae (gastroesophageal, anal, peristomal) -----> Development of varices. Risks factors for rupture: 1. portosystemic pressure gradient > 10-12 mmHg ii. variceal size > 5mm iii. progressive hepatic dysfunction.

    Treatment goal:
    1. Resuscitation
    -airway control in massive haemorhage and obtunded patients
    -NG aspiration may be necessary
    -hemodynamic with blood and blood products aim for stability (initial lab results)
    -watch for hypocalcemia and thrombocytopenia in massive transfusion
    -thiamine and monitor alcohol withdrawal

    2. Diagnosis-upper endoscopy
    Findings-fresh fibrin clot from varix, nipple like protrusion, red signs, varices with no other potential bleeding source.

    3. Therapy

    A. Pharmacology:
    1. Octreotide (somatostatin analog) is the drug of choice. Started immediately with suspicion of variceal bleeding. Minimal side effects
    IV 50mcg bolus, infusion 50mcg/hr
    2. vasopressin -potent vasoconstrictor, reduces splanchnic BF and portal pressure. Adverse cardiac events (MI, hypertension) in ~ 30% of patients. Concurrent IV nitroglycerin for SBP ~100mmhg has been shown to reduce the systemic SE's.
    3. Non selective B blockers, not in acute setting. For primary and secondary prevention of variceal bleeding.
    4. Antibiotic prophylaxis- to prevent infection and rebleeding in all cirrhotic patients with variceal bleeding.
    Norfloxacin 400mg bd
    or Ceftriaxone 1g daily

    B. Endoscopy
    1. Band ligation- is the technique of choice to control bleeding. Active bleeding is controlled in 80%-90% of patients after one or two treatments.
    -lower incidence of esophageal ulceration, stricture formation, perforation, bacrteraemia and respiratory failure compared to sclerotherapy.
    2. Sclerotherapy - for gastric variceal bleeding and massive variceal bleeding

    C. TIPS



    Transjugular Intrahepatic Pportosystemic Stent (TIPS) shunt

    - Iatrogenic fistula between radicals of the hepatic and portal veins, created by interventional radiologists using ultrasonographic and fluoroscopic guidance
    - An expandable metal stent is left in place and portosystemic pressue gradient is reduced to less than 12 mmHg

    Indications:

    i. Bleeding continues despite combinations of pharmacologic and endoscopic therapies
    ii. Bleeding recurs after two endoscopic attempts at prevention
    iii. Bleeding has occurred from gastric varices or portal hypertensive gastropathy

    - The technical success rate is > 90%, with near universal success rate in bleeding control. Overall mortality is similar to endoscopic therapy.
    -S hunt insufficiency is 15-60% within 6 months.
    - Postprocedure bleeding recurrence---> dopler US examination for determining shunt patency. Revision of shunt usually results in low mortality

    Complications:

    - 20-30% develop transient deterioration of LFTs
    - Up to 25% may experience new or worsened hepatic encephalopathy

    D. Baloon tamponade
    -gastric and oesophageal balloon devices for direct tamponade of the bleeding varices
    -Sengstaken-Blakemore, Minnesota and Linton-Nachlas balloons--> for severe and persistent bleeding.

    E. Other measures:
    - surgical shunts
    -non shunting operations
    -embolisation of the short gastric veins in gastric variceal bleeding and splenectomy in splenic vein thrombosis
    .........................................................................................................................................................................
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    SOMATOSTATIN AND ITS ANALOGS

    Somatostatin inhibits the release of vasodilator hormones, such as glucagon, indirectly causing splanchnic vasoconstriction and decreased portal inflow.

    It has a short half-life and disappears within minutes of a bolus infusion; octreotide is a long-acting analog of Somatostatin.

    Pharmacodynamics — Following a bolus injection of either somatostatin or octreotide, portal venous inflow, portal pressures, azygos flow, and intravariceal pressures decrease within seconds. Of these effects, the changes in portal pressures, as measured by wedged hepatic pressures, are most variable and the decrease in collateral flow (azygos flow) are most consistently observed.


    One of the most detailed studies to evaluate the pharmacodynamics of octreotide included 68 patients with cirrhosis who were given octreotide by four different methods (gastroenterology 2001):
    -An intravenous injection of (50 or 500 microg) or placebo
    -A 50 microg bolus followed by continuous infusion of 50 or 250 microg per hour or placebo infusion
    -Repeated 50 microg injections or placebo after an initial 50 microg bolus
    -After a placebo bolus and continuous infusion of 50 microg per hour.


    Octreotide caused a marked but transient decrease in portal pressure and azygos blood flow and an increase in mean arterial pressure. These effects lasted only five minutes even with the addition of continuous infusions. Repeated bolus injections had shorter, less marked effects while continuous infusion did not decrease portal pressure, suggesting that there was rapid desensitization.
    These findings make it unclear why octreotide should be of any benefit in portal hypertension since its effect on portal pressure is short-lived. However, the potential benefits of octreotide (and somatostatin) in portal hypertension may extend beyond the measures noted above. Both inhibit the release of glucagon and other hormones that have an important role in mediating the normal increase in mesenteric blood flow that occurs postprandially.

    Variceal hemorrhage is associated with an increase in intestinal blood flow, presumably mediated by pathways that are activated by the presence of blood, a high protein substance, in the gut. Octreotide can blunt this response for at least 48 hours . In addition, activation of somatostatin receptors may decrease the rebound increase in portal venous pressure that occurs when blood enters the gastrointestinal tract and during correction of hypovolemia.


    Clinical trials

    A number of clinical trials have compared somatostatin or octreotide to either vasopressin or placebo in the management of active bleeding. An initial placebo-controlled trial failed to demonstrate a benefit for somatostatin; however, over 80 percent of those treated with placebo spontaneously stopped bleeding which may have obscured a treatment benefit . Several subsequent studies have shown somatostatin to be significantly superior to placebo with respect to achievement of hemostasis and to prevention of early rebleeding .


    Somatostatin versus vasopressin — Somatostatin is also superior to vasopressin and balloon tamponade due in part to the virtual absence of side effects. A meta-analysis of trials comparing somatostatin to vasopressin found two benefits with somatostatin [gastroenterology 1995]:
    1. A higher relative risk (1.62, 95 percent CI 1.37 to 1.93) of achieving initial control of the bleeding; the absolute benefit was such that only three or four patients had to be treated with somatostatin for one to derive benefit over therapy with vasopressin.
    2. A lower risk of adverse effects (0 versus 10 percent with vasopressin).


    However, these beneficial effects on bleeding have not been shown to improve survival.

    The Liver




    The liver has anatomically separate lobes and eight functionally independent segments based on blood supply and natural anatomic separations. These segments are used for surgical classification because they allow for hepatic resection along segmental planes, thus preserving function and tissue integrity. The surgical classification system is called Couinad's classification.

    The four major lobes of the liver are divided by fissures and include:
    i. the right anatomical lobe (larger), which has two smaller lobes located at its posterior-inferior surface
    ii. the left anatomical lobe
    iii. the smaller, inferior lobes are referred to as the caudate lobe and
    iv. quadrate lobe.
    The major division of the liver (left and right lobes) is the falciform ligament .

    The human liver is the largest gland/organ in the body and weighs approximately 1500-1600 gm in adults (~2% of total body mass). It is known for having a large functional reserve and is responsible for an extensive number of complex functions in humans including:

    1. Blood reservoir / filter
    2. Regulation of blood coagulation
    3. Glucose regulation
    4. Erythrocyte breakdown and bilirubin excretion
    5. Intermediary metabolism regulation (bile production)
    6. Protein synthesis (albumin, coagulation factors, etc.)
    7. Host defense
    8. Pharmacokinetics / Drug metabolism
    9. Hormone metabolism


    Functional and Microanatomy

    Hepatic tissue is made of 50,000-100,000 discrete, hexagonally shaped anatomic units called lobules . Lobules contain plates of hepatocytes arranged cylindrically around a centrilobular vein .

    The portal tracts (or “triads”) include 4-5 tracks surrounding each lobule that contain
    - hepatic arterioles which carry oxygenated blood from hepatic artery,
    - the portal venules which carry partially deoxygenated blood from the portal vein,
    - bile caniliculi that join to form bile ducts.



    The hepatic sinusoids / ducts act as capillaries between the central vein and portal tracts and contain endothelial cells and macrophages ( Kupffer cells ).
    Kupffer cells are responsible for phagocytosis of calonic bacteria, endotoxins, cellular debris, viruses, proteins, and particulate matter, antigen processing, and the release of proteins, enzymes, cytokines, and chemical mediators.
    The Space of Disse lies between the hepatic sinusoids and the hepatocytes.
    Additionally, and extensive system of lymphatic ducts and nerves is located through hepatic tissue.

    The functional cellular anatomy of the liver can be divided into three zones:

    - Zone 1 – closest to blood vessels, well oxygenated, least susceptible to injury
    - Zone 2 – adequately oxygenated
    - Zone 3 – closest to centrilobular vessels, least oxygenated, most susceptible to injury



    Blood Supply


    Normal hepatic blood flow is ~1500 cc/min in adults (25-30% of total CO) and normal hepatic blood volume is ~450 cc. The liver has the unique ability to augment circulating blood volume by up to 300 cc during low volume states such as dehydration or hemorrhage. Additionally, it can also hold up to 1 L of blood at the expense of hepatic congestion. The blood supply is a dual system also known as a portal system. The two major vessels that provide blood to the liver are the hepatic artery and portal vein .

    The hepatic artery arises from the celiac artery (from aorta) and comprises 25-30% of total blood flow to the liver. It supplies 45-50% of oxygen requirement and flow is dependant on metabolic demand (autoregulated). The normal saO2 of blood in the hepatic artery is 98%. The portal vein is formed at the anastamosis of the superior mesenteric and splenic veins and comprises 70-75% of total blood flow to the liver. It supplies 50-55% of oxygen requirement and the normal saO2 of portal venous blood is 85%. This blood is partially deoxygenated prior to entering the liver in the stomach, spleen, intestines, and pancreatic vessels. Normal hepatic venous pressure is 7-10 mmHg and flow is dependent on blood flow to the GI tract and spleen. The blood from these organs is laden with nutrients from GI tract.


    The intrahepatic circulation of blood is as follows:

    The hepatic artery and portal vein split into left and right branches ---> enter liver and diminish in size throughout the hepatic tissue ---> become terminal hepatic arterioles and portal venules ---> drain directly into hepatic sinusoids (see above) ---> terminal hepatic venules into a central vein ---> sublobular veins which get larger and ultimately form ---> three major hepatic veins (right, middle, and left) ---> inferior vena cava.

    Duct System



    The duct system or hepatobiliary system is composed of the following:
    i. Bile ducts from hepatic lobules combine to form
    ii. the left and right hepatic ducts which connect to form the hepatic duct which together with
    iii. the cystic duct from the gallbladder form
    iv. the common bile duct which then meets with
    v. the pancreatic duct and empties into the duodenum of the small intestine under the control of the Sphincter of Oddi:

    Contract: bile is blocked from entering the duodenum

    Relax: allows bile to enter the duodenum










    THE HEPATIC PORTAL SYSTEM




    The Hepatic Portal System

    Introduction:
    Portal System begins in the capillaries of the digestive organs and ends in the portal vein. Consequently, portal blood contains substances absorbed by the stomach and intestines. Portal blood is passed through the hepatic lobules where nutrients and toxins are absorbed, excreted or converted. Restriction of outflow through the hepatic portal system can lead to portal hypertension.


    The liver is unusual in that it has a double blood supply:

    1. The right and left hepatic arteries carry oxygenated blood to the liver
    2. The portal vein carries venous blood from the GI tract to the liver.

    The venous blood from the GI tract drains into the superior and inferior mesenteric veins; these two vessels are then joined by the splenic vein just posterior to the neck of the pancreas to form the portal vein. This then splits to form the right and left branches, each supplying about half of the liver.On entering the liver, the blood drains into the hepatic sinusoids, where it is screened by specialised macrophages (Kupffer cells) to remove any pathogens that manage to get past the GI defences. The plasma is filtered through the endothelial lining of the sinusoids and bathes the hepatocytes; these cells contain vast numbers of enzymes capable of braking down and metabolising most of what has been absorbed.

    The portal venous blood contains all of the products of digestion absorbed from the GI tract, so all useful and non-useful products are processed in the liver before being either released back into the hepatic veins which join the inferior vena cava just inferior to the diaphragm, or stored in the liver for later use.


    The venous blood from the GI tract drains into the superior and inferior mesenteric veins; these two vessels are then joined by the splenic vein just posterior to the neck of the pancreas to form the portal vein.

    This then splits to form the right and left branches, each supplying about half of the liver.On entering the liver, the blood drains into the hepatic sinusoids, where it is screened by specialised macrophages (Kupffer cells) to remove any pathogens that manage to get past the GI defences. The plasma is filtered through the endothelial lining of the sinusoids and bathes the hepatocytes; these cells contain vast numbers of enzymes capable of breaking down and metabolising most of what has been absorbed.

    The portal venous blood contains all of the products of digestion absorbed from the GI tract, so all useful and non-useful products are processed in the liver before being either released back into the hepatic veins which join the inferior vena cava just inferior to the diaphragm, or stored in the liver for later use.

    Chronic liver injury results in activation of stellate cells within the space of Disse. This leads to the deposition of collagen and in time histologic changes of cirrhosis.
    Cirrhosis also results in endothelial dysfunction and increased in resistance to flow within the hepatic sinusoids.

    Sinusoidal hypertension and endothelial dysfunction produce Portal hypertension.

    Three cardinal features:

    1. Increased resistance to mesenteric vascular flow
    2. Activation of the renal-angiotensin-aldosterone system resulting in Na and water retention and increased intravascular volume.
    3. Increased mesenteric blood flow as a consequence of a hyperdynamic circulation.


    Portal hypertension is responsible for the 5 complications of chronic liver disease:

    1. Gastrointestinal bleeding

    2. Ascites

    3. Portosystemic encephalopathy

    4. Hepato renal syndrome

    5. Pulmonary disease:
    a. Hepatopulmonary syndrome
    b. Portopulmonary hypertension

    The consequences of portal hypertension are due to portal systemic anastomosis formed by the body as an attempt to bypass the obstructed liver circulation. These collateral vessels form along the falciform ligament, diaphragm, spleen, stomach and peritoneum. The collaterals find their way to the renal vein where blood drained from the digestive organs is let into the systemic circulation.

    Monday, February 1, 2010

    Oesophageal Tamponade Tube



    Oesophageal Tamponade Tube

    Oesophageal varices arise as a result of portal hypertension. Bleeding oesophageal varices are associated with significant risk of mortality. Definitive management includes endoscopic sclerotherapy/banding +/- octreotide or transjugular intrahepatic portosystemic shunt (TIPS).

    Indication:

    1. Bleeding oesophageal varices
    2. Failure of sclerotherapy/banding +/- octreotide to control bleeding
    3. Delay or lack of availability of endoscopic intervention

    Sengstaken –Blakemore (Minnesota modification) 4 channel tube:
    Gastric Balloon
    Gastric aspiration lumen
    Oesophageal balloon
    Oesophageal aspiration lumen

    Policy guideline

    The decision to insert a tube is made with consultation with the duty consultant intensivist and the duty consultant gastroenterologist/ general surgeon
    All patients are to be endotracheally intubated prior insertion of Sengstaken-Blakemore tube
    All patients are to be managed in the ICU
    Risk of rebleeding after balloon insertion is 50%, all patients should undergo subsequent endoscopy and sclerotherapy after tube is removed.

    Procedure


    Check tube before insertion
    Inflate the gastric balloon with 300 ml air, check and record the pressure in the in inflated gastric balloon
    Inflate the oesohageal balloon with air, check and record the pressure in the inflated oesophageal balloon
    Deflate both balloons completely and lubricate the tube
    Insert tube orally under direct vision, using a laryngoscope; pass the tube to the 50-cm mark.
    Do not inflate gastric balloon until correct tube placement is confirmed with X-Ray
    Aspirate gastric lumen
    Inflate gastric balloon with 300 ml of air, check the pressure in the gastric balloon, this should not exceed the pre insertion pressure by > 5 mmHg if the tube is correctly placed in the stomach. Higher pressures may indicate incorrect oesophageal placement, if high pressures present deflate balloon and repeat insertion and check X-Ray
    Pull back tube until resistance is felt when the inflated gastric balloon rests in gastric fundus and against the oesophageal gastric junction
    Apply traction (0.5-1kg) to the tube, i.e. 500ml or 100ml bag of fluid by pulley and cord
    Inflate oesophageal balloon to a pressure of 35-40 mmHg
    Recheck the position of the tube with X-Ray
    Place on free drainage oesophageal and gastric lumens, and aspirate hourly or prn. Record aspirate and drainage volumes hourly to assess haemorrhagic losses
    Balloons should not be inflated for > 24 hours

    Contraindications:

    . Known oesophageal stricture

    . Unidentified source of bleeding

    . Unprotected airway

    Complications.

    . Cardiac arryythmias
    · Acute upper airway obstruction
    · Oesophageal necrosis / rupture
    · Aspiration pneumonia


    The Sengstaken-Blakemore tube permits tamponade of both the distal esophagus and the gastric fundus. An accessory nasogastric tube permits aspiration of secretions from above the esophageal balloon.