Wednesday March 18, 2009


Q: Why blood in pleural fluid does not clot?

Answer: Hemorrhage within the pleural space generally does not clot due to 3 reasons

1. mechanical defibrination (movement of lungs)
2. activation of fibrinolytic mechanisms
3. Also, platelets disappears within hours following hemorrhage

Tuesday March 17, 2009


Q: What is your diagnosis.

Second degree (Wenckebach) AV block or Third degree AV block?

Answer: Third degree AV block

Though it appears that PR interval is progressively getting bigger (like second degree wenckebach block) - but on close inspection - P waves and QRS complexes are marching independently.

Monday March 16, 2009

Q: Describe any other related IV use of Narcan (NALOXONE), beside its use as an anti-dote for narcotic overdose?


Answer: To counter-act pruritus associated with epidural analgesia.

To neutralize pruritis caused by an opiate, without compromising analgesic effect - continuous drip can be prepared with 4 mg of Narcan in 250 cc D5W or D5NS = 16 mcg/cc and can be given at rate of 1 mcg/kg/h. It can be titrated upto 5 mcg/kg/h as tolerated.

Related Previous Pearl: Oral Narcan for opioid induced constipation !

Sunday March 15, 2009

Q: Describe the inflation and deflation cycle of intermittent pneumatic compression boots?



Answer: The pump runs on 60-second cycles:

• 12 seconds of inflation and
• 48 seconds of deflation

The cycle alternates so that inflation to one leg begins 30 seconds after inflation to the other.

The standard pump pressure is usually 40 mm Hg.

Saturday March 14, 2009
Thromboelastography Maximum Amplitude Predicts Postoperative Thrombotic Complications Including Myocardial Infarction

Background: Postoperative thrombotic complications increase hospital length of stay and health care costs. Given the potential for thrombotic complications to result from hypercoagulable states, study sought to determine whether postoperative blood analysis using thromboelastography could predict the occurrence of thrombotic complications, including myocardial infarction (MI).

Design: Prospectively 240 patients were enrolled undergoing a wide variety of surgical procedures. A cardiac risk score was assigned to each patient using the established revised Goldman risk index. Thromboelastography was performed immediately after surgery and maximum amplitude (MA), representing clot strength, was determined. Postoperative thrombotic complications requiring confirmation by a diagnostic test were assessed by a blinded observer.

Results: Ten patients (4.2%) suffered a total of 12 postoperative thrombotic complications.

• The incidence of thrombotic complications with increased MA (8 of 95 = 8.4%) was significantly more frequent than that of patients with MA less than/= 68 (2 of 145 = 1.4%).
• The percentage suffering postoperative MI in the increased MA group (6 of 95 = 6.3%) was significantly larger than that in the MA less than/=68 group (0 of 145 = 0%).
• In a multivariate analysis, increased MA and Goldman risk score both independently predicted postoperative MI.

Conclusion; A postoperative hypercoagulable state as determined by thromboelastography is associated with postoperative thrombotic complications, including MI, in a diverse group of surgical patients.

Reference:

Thromboelastography Maximum Amplitude Predicts Postoperative Thrombotic Complications Including Myocardial Infarction - Anesth Analg 2005;100:1576-1583

Friday March 13, 2009 (pediatric pearl)
Is a drop in effective plasma osmolality (P(Eff osm); 2 x plasma sodium [P(Na)] + plasma glucose concentrations) during therapy for diabetic ketoacidosis (DKA) is associated with an increased risk of cerebral edema?

Is the development of hypernatremia to prevent a drop in the P(Eff osm) is dangerous?

In a retrospective comparison of a CE group (n = 12) and non-CE groups with hypernatremia (n = 44) and without hypernatremia (n = 13) the development of CE (at 6.8 +/- 1.5 hours) was associated with a drop in P(Eff osm) from 304 +/- 5 to 290 +/- 5 mOsm/kg (P less than .001). Control patients did not show this drop in P(Eff osm) at 4 hours (1 +/- 2 and 2 +/- 2 vs -9 +/- 2 mOsm/kg; P less than .01), because of a larger rise in P(Na) and/or a smaller drop in plasma glucose.

During this period, the CE group received more near-isotonic fluids (69 +/- 9 vs 35 +/- 2 and 27 +/- 3 mL/kg; P less than .001). The CE group had a higher mortality (3/12 vs 0/57; P = .003), and more neurologic sequelae (5/12 vs 1/57; P less than .001).

Conclusion: Cerebral edema during therapy for DKA was associated with a drop in P(Eff osm). An adequate rise in P(Na) may be needed to prevent this drop in P(Eff osm).


Reference:

Preventing a drop in effective plasma osmolality to minimize the likelihood of cerebral edema during treatment of children with diabetic ketoacidosis- J Pediatr. 2007 May;150(5):467-73

Thursday March 12, 2009
Milrinone Increases Flow in Coronary Artery Bypass Grafts After Cardiopulmonary Bypass?

Interesting study !

Objective: To compare the effects of a bolus of milrinone, 50 μg/kg, versus placebo on flow in coronary artery bypass grafts after cardiopulmonary bypass (CPB).

Design: A prospective, randomized, double-blind study. 44 patients with stable angina and left ventricular ejection fraction more than 30% scheduled for elective coronary artery bypass graft (CABG) surgery were included.

Intervention: Patients were randomized to receive 50 μg/kg of milrinone (n = 22) or placebo (n = 22) after aortic declamping.

Results: The flow in coronary artery bypass grafts was measured with a transit time flow meter at 10 minutes and 30 minutes after termination of CPB. The hemodynamic evaluation included transesophageal echocardiography, mean arterial pressure (MAP), heart rate, and intracavitary measurement of left ventricular end-diastolic pressure (LVEDP).

• The flow in the saphenous vein grafts was significantly higher in the milrinone group when compared with the placebo group both at 10 and 30 minutes after termination of CPB (p <>
• At 10 minutes, the flow was 64.5 ± 37.4 mL/min (mean ± standard deviation) and 43.6 ± 25.7 mL/min in nonsequential vein grafts for milrinone and placebo, respectively. Corresponding values at 30 minutes were 54.8 ± 29.9 mL/min and 35.3 ± 22.4 mL/min.
• The left internal thoracic artery (LITA) flow was higher in the milrinone group but did not reach statistical significance.
• The fractional area change was higher, and the MAP and calculated pressure gradient (MAP-LVEDP) were lower at 10 minutes in the milrinone group.

Conclusion: Milrinone significantly increases the flow in anastomosed saphenous vein grafts after CPB, and has beneficial effects on left ventricular function.


References:

Milrinone Increases Flow in Coronary Artery Bypass Grafts After Cardiopulmonary Bypass: A Prospective, Randomized, Double-Blind, Placebo-Controlled Study - Journal of Cardiothoracic and Vascular Anesthesia, Volume 23, Issue 1, Pages 48-53 (February 2009)
.

Wednesday March 11, 2009
Glucose in bronchial secretions and MRSA

Interesting paper by Philips et al inThorax reports a possible association between a positive culture for MRSA from bronchial aspirates from patients in ICU and abnormally high levels of glucose in the bronchial aspirates (ranging from 2.7 to 4.4 mmol/l = 50-80 mg/dl).

Background: The risk of nosocomial infection is increased in critically ill patients by stress hyperglycaemia. Glucose is not normally detectable in airway secretions but appears as blood glucose levels exceed. We hypothesise that the presence of glucose in airway secretions in these patients predisposes to respiratory infection.
Methods: An association between glucose in bronchial aspirates and nosocomial respiratory infection was examined in 98 critically ill patients. Patients were included if they were expected to require ventilation for more than 48 hours. Bronchial aspirates were analysed for glucose and sent twice weekly for microbiological analysis and whenever an infection was suspected.

Results: Glucose was detected in bronchial aspirates of 58 of the 98 patients.

• These patients were more likely to have pathogenic bacteria than patients without glucose detected in bronchial aspirates (relative risk 2.4 (95% CI 1.5 to 3.8)).
  
• Patients with glucose were much more likely to have methicillin resistant Staphylococcus aureus (MRSA) than those without glucose in bronchial aspirates (relative risk 2.1 (95% CI 1.2 to 3.8)).
  
• Patients who became colonised or infected with MRSA had more infiltrates on their chest radiograph, an increased C reactive protein level, and a longer stay in the intensive care unit.

Conclusion: The results imply a relationship between the presence of glucose in the airway and a risk of colonisation or infection with pathogenic bacteria including MRSA.



References:

Glucose in bronchial aspirates increases the risk of respiratory MRSA in intubated patients - Thorax 2005;60:761-764;

Tuesday March 10, 2009
A note on end-tidal carbon dioxide (ETCO2) during CPR

Expired carbon dioxide is a reliable measure of pulmonary perfusion and thus cardiac output (if ventilation is held constant) because carbon dioxide is excreted by the blood into the lungs. Carbon dioxide is easily measured with a portable capnometer placed between the end of an endotracheal tube and a resuscitation bag.

Several studies have shown the correlations between ETCO2 and cardiac output and myocardial perfusion pressure, implying that continuous measurement may gauge the effectiveness of ongoing CPR. Patients with higher ETCO2 partial pressures during CPR has higher chances of ROSC (return of spontaneous circulation). Atleast ETCO2 partial pressure of 10 mm Hg (or greater) is a predictor of survival - preferably 15 or more mm Hg.

Levine et al prospectively measured ETCO2 in 150 consecutive victims of cardiac arrest outside the hospital. The sensitivity, specificity, positive predictive value, and negative predictive value of a 20-minute ETCO2 level of less than10 mm Hg were all 100% 2.

References:

1. Sanders AB, Kem KB, Otto CW, Milander MM, Ewy GA. End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation. A prognostic indicator for survival. JAMA 1989;262:1347-51.

2. Levine RL, Wayne MA, Miller CC. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest. N Engl J Med 1997; 337:301-6.

Monday March 9, 2009


Q: What is Modified Rankin Scale?


Answer: The modified Rankin Scale, also written as mRS is a commonly used scale for measuring the degree of disability or dependence in the daily activities of people who have suffered a stroke. It was originally introduced in 1957 by Rankin. It was modified in 1988.

SCORE

0 = No symptoms at all

1 = No significant disability despite symptoms; able to carry out all usual duties and activities

2 = Slight disability; unable to carry out all previous activities, but able to look after own affairs without assistance

3 = Moderate disability; requiring some help, but able to walk without assistance

4 = Moderately severe disability; unable to walk without assistance and unable to attend to own bodily needs without assistance

5 = Severe disability; bedridden, incontinent and requiring constant nursing care and attention

6 = Dead


References

Rankin J. “Cerebral vascular accidents in patients over the age of 60.” Scott Med J 1957;2:200-15.
Bonita R, Beaglehole R. “Modification of Rankin Scale: Recovery of motor function after stroke.” Stroke 1988 Dec;19(12):1497-1500

Sunday March 8, 2009
DVTs in ICUs

Q: Despite universal thromboprophylaxis, medical-surgical critically ill patients remain at risk for lower extremity deep venous thrombosis. Name few independent risk factors for intensive care unit-acquired deep venous thrombosis?


Answer:

• personal or family history of venous thromboembolism
• end-stage renal failure
• platelet transfusion
• vasopressor use

Reference: Click to get abstract

Deep venous thrombosis in medical-surgical critically ill patients: Prevalence, incidence, and risk factors - Critical Care Medicine:Volume 33(7)July 2005pp 1565-1571

Saturday March 7, 2009


Q: Which pressor is preferable to counter-act vasodilatation (hypotension) induced by milrinone during or immediate post-op Coronary bypass surgery? (choose one)

A) Norepinephrine
B) Dopamine
C) Vasopressin
D) Phenylepherine


Answer: Vasopressin

Phosphodiesterase inhibitor is used during coronary bypass surgery in management of decompensated heart failure because it increases contractility and decreases afterload of right ventricle. It also improves hemodynamics and increases blood flow of the grafted internal mammary arteries and middle cerebral arteries during coronary artery bypass surgery. However, it induces vasodilation and necessitates the use of vasoconstrictors.

In the patients undergoing CABG surgery, both norepinephrine and low dose vasopressin were effective in restoring milrinone-induced decrease of SVR. However, only low-dose vasopressin decreased the PVR/SVR ratio that was increased by milrinone. Considering the importance of maintaining systemic perfusion pressure as well as reducing right heart afterload, milrinone–vasopressin may provide better hemodynamics than milrinone–norephinephrine during the management of right heart failure.

SVR = systemic vascular resistance
PVR = pulmonary vascular resistance


Reference: Click to get abstract

Comparative hemodynamic effects of vasopressin and norepinephrine after milrinone-induced hypotension in off-pump coronary artery bypass surgical patients - European Journal of Cardio-Thoracic Surgery, Volume 29, Issue 6, Pages 952-956 (June 2006)

Friday March 6, 2009 (pediatric pearl)

Is the survival of pediatric oncology patients with severe sepsis any different from those without oncologic malignancies?

In a retrospective study patients (446 ICU admissions of 359 eligible patients) with cancer admitted to the ICU with severe sepsis overall ICU mortality was 17%. 30% in post-bone marrow transplant (BMT) admissions and 12% in non-BMT admissions. In the 106 admissions progressing to septic shock and requiring both mechanical ventilation and inotropic support, ICU mortality was 64% with BMT patients carrying a significantly lower survival rate than non-BMT patients (26% vs. 44%).

6-month survival was 69% among non-BMT patients vs. 39% for BMT patients. When the 38 patients who survived to ICU discharge after requiring both mechanical ventilation and inotropic/vasopressor support are considered 71% were alive at 6 months after ICU discharge (81% non-BMT vs. 19% for BMT patients.

Factors significantly associated with ICU mortality in admissions requiring both mechanical ventilation and inotropic support identified four variables:

• BMT,
• fungal sepsis,
• use of multiple inotropes, and
• Pediatric Risk of Mortality III score
  

The results regarding ICU survival are useful in that the overall mortality (83%) in these particular study subjects are in line with current estimates. This implies that they carry the same prognosis as any other pediatric patient with severe sepsis. However, when comparing those patients who underwent BMT versus those who did not, the BMT patients carried a significantly lower survival rate (70% vs. 88%). The number of patients alive at 6 months and the encouraging ICU survival rate further justifies the use of aggressive ICU interventions in this population. This is useful in that it may help provide patients/parents with realistic goals and expectations of outcome.

Reference: Click to get abstract

Outcome of severe sepsis in pediatric oncology patients - Pediatr Crit Care Med. 2005 Sep;6(5):531-536

Thursday March 5, 2009
Influence of Nebulized Unfractionated Heparin and N-Acetylcysteine in Acute Lung Injury after Smoke Inhalation Injury

Andrew Miller did an interesting study to see effect of addition of nebulized unfractionated heparin, and NAC in lung injury after smoke inhalation. They studied 30 mechanically ventilated adult subjects who were admitted within 48 hours of their bronchoscopy confirmed smoke inhalation injury over a 5-year period.

The experimental group was treated with nebulized heparin sulfate, N-acetylcystine, and albuterol sulfate. Controls received ventilation support and albuterol sulfate. The authors calculated acute physiology and chronic health evaluation (APACHE)-III scores on admission in addition to daily LIS for 7 days.

The experimental group showed significant improvement in (Lung Injury Scores) LISs, respiratory resistance and compliance measurements, and hypoxia scores as compared with controls throughout the duration of the study. There was a statistically significant survival benefit in the experimental group that was most pronounced in patients with APACHE-III scores more > 35. Survival for the control vs. experimental group was 0.5714 ± 0.1497 vs. 0.9375 ± 0.0605, respectively, (risk ratio -0.0055; 95% confidence interval -0.0314-0.0204; hazard ratio 1.003; number needed to treat 2.7)

Conclusion: The use of aerosolized unfractionated heparin and N-acetylcystine attenuates lung injury and the progression of acute respiratory distress syndrome in ventilated adult patients with acute lung injury following smoke inhalation.


Reference:

Miller A, Rivero A, Zaid S, Smith D, Elamin E. Influence of Nebulized Unfractionated Heparin and N-Acetylcysteine in Acute Lung Injury after Smoke Inhalation Injury. Journal of Burn Care & Research:Volume 2009; 30(2): 249-256

Wednesday March 4, 2009
Hypothermia after cardiac arrest: Have we gone overboard

Frieberg and Neilsen looked at the two published trial for this purpose.

Objective: The aim of the study was to evaluate the actual use of hypothermia in clinical practice, safety aspects, resource utilization, and outcome in large cohorts of patients.

Method: They looked at the two published studies from two separate registries, including 2205 cardiac arrest patients in 39 different sites, of whom 869 (39%) were treated with induced hypothermia. Another registry, The Hypothermia Registry, includes 1108 patients from 37 sites in six European countries and one center in the United States; a large majority, or 952 patients (86%), were treated with hypothermia.

Conclusions: Hypothermia is feasible to implement, that it seems reasonably safe, and that the outcome compares well with previous reports. They also conclude that the treatment with hypothermia after cardiac arrest is more widely applied than what is strictly evidence based.


Editors' comment: Institutions need to develop, implement and follow guidelines for post-cardiac arrest therapeutic hypothermia to avoid indiscriminate use and save costs.


Reference:

Frieberg H, Nielsen N. Hypothermia after Cardiac Arrest: Lessons Learned from National Registries. Journal of Neurotrauma. ahead of print. doi:10.1089/neu.2008.0637.

Tuesday March 3, 2009
Minimally invasive craniopuncture therapy for basal ganglia bleed

Study by Wen-Zhi Wang from china help to shed some light on this issue. They evaluated the effects of minimally invasive craniopuncture therapy compared with conservative treatment in treating intracerebral hemorrhage (25–40 ml) in the basal ganglion.

Method: A multicenter, randomized control clinical trial comprised 465 cases of hemorrhage in the basal ganglion from 42 hospitals in China. Three hundred and seventy-seven patients with hemorrhage were randomly assigned to receive

• minimally invasive craniopuncture therapy (n=195) or
• conservative control treatment (n=182)

The main indices of evaluation were

• the degree of neurological impairment at the 14th day after treatment,
• activities of daily living at the end of the 3rd month and
• the case fatality within 3 months

Results:

• Improvement of neurological function in the minimally invasive craniopuncture group was significantly better than that in the control group at the 14th day (χ2=7·93, P=0·02).
• At the end of the 3rd month, there was a significant difference between the two groups in activities of daily living score (χ2=23·13, P<0·001).>The proportion of dependent survival patients (modified Rankin scale >2) in the craniopuncture group (40·9%) was significantly lower than that in the conservative group (63·0%) at the end of the 3rd month (χ2=16·95, P<0·01).>There was no significant difference in the cumulative fatality rates within three months between the two groups [6·7% (13/195) in the craniopuncture group and 8·8% (16/182) in the conservative group].

Conclusions: Minimally invasive craniopuncture technique can improve the independent survival of patients with small basal ganglion hemorrhage. It is a safe and practical technique in treating cerebral hemorrhage.



Reference: click to get abstract

Zhi Wnag W, Jiang B, Mei Liu H, et al. Minimally invasive craniopuncture therapy vs. conservative treatment for spontaneous intracerebral hemorrhage: results from a randomized clinical trial in China International Journal of Stroke 2009; 4(1): 11-16

Monday March 2, 2009


Q: Why oxygen should be administered to every patient with suspected PE, even when the arterial PO2 is perfectly normal?


Answer; Oxygen should be administered to every patient with suspected PE, even when the arterial PO2 is perfectly normal, because increased alveolar oxygen may help to promote pulmonary vascular dilatation.

Sunday March 1, 2009


Q: In which clinical condition, usually a lower maintenance dose of warfarin is required?


Answer; In thyrotoxic atrial fibrillation

The recommended loading dose of warfarin in thyrotoxic atrial fibrillation is similar to euthyroid patients, but a lower maintenance dose is required because of accelerated clearance of vitamin K-dependent clotting factors.



Reference:

Shenfield GM. Influence of thyroid dysfunction on drug pharmacokinetics. Clin Pharmacokinet. 1981;6:275-297