Sunday January 13, 2008
Back to basics !! - trivia on sunday

Though various scales and calculators are now available online and handy at bedside, but being an intensivist its important to atleast remember few basic formulae. Judge yourself. Ask yourself out of following 5 basic formulae, which one you can recall right.

1. Body Surface Area
2. Systemic Vascular Resistance
3. A-a Gradient
4. Static Compliance
5. Creatinine Clearence




Answers:

1. BSA = Sqrt of [Wt (kgs) x Ht (cms)/3600]

2. SVR = [(MAP -CVP)/CO] 80 dynes/sec x cm-5 Normal: 900-1200 dynes/sec x cm-5

3. A-a Gradient = [(FiO2 /100) (760 - 47)] - (PaCO2 /0.8) - PaO2 Normal is less than 10 torr
4. Static Compliance = VT/Pplateau - PEEP Normal >60 mL/cm H2O

5. Creatinine Clearence = 140-Age x Weight (Kg)/ 72 xSerum creatinine ( x 0.85 for feamles)

Saturday January 12, 2008

Heparin and Insulin - mixup? - FDA warning

Friday January 11, 2008
Changeovers of vasoactive drug infusion pumps

Hemodynamic instability during the changeover of vasoactive infusion pump (CVIP) is a common site in ICUs. Interesting article published very recently in Critical Care 1 in which the impact of a "quick change method" of CVIP (2 syringes) was assessed and compared with regular (single syringe) method.

Study was done (compared) in 2 phases.

Phase 1: In this phase, nurses were free to choose the method of changeover of CVIP they usually practice.

Phase 2: In this phase, strategy called “quick change method” is applied. using two syringe drivers. This consisted loading the new infusion with a new line into a new syringe pump, and priming the line when the running infusion was about to finish. Nurses started the pump and chose a high flow rate until a drop of vasoactive drug appeared on the end of the line, in order to avoid a start up delay. Next, they programmed the pump to same rate and setting as the previous infusion. After that, they removed the cap from the spare port of the three-way stopcock and connected it the new infusion pump. Then, they turned the three-way stopcock on to the new infusion, which closed the lumen of the old infusion. Lastly, they had to disconnect the old infusion and put a cap on the new spare port.

913 changeovers of infusion pumps were evaluated: 435 in phase 1 and 478 in phase 2.

Results: The frequency of incidents was significantly reduced in phase 2 (5.9%, n=28) versus phase 1 (17.8%, n=78) with 98% of incidents were blood pressure variations.





References: click to get abstract / article

1. Changeovers of vasoactive drug infusion pumps: impact of a quality improvement program - pdf file, Critical Care 2007, 11:R133

Thursday January 10, 2008


Q; Which beta-blocker is prone to cause life-threatening hyperkalemia particularly in kidney transplant patient?

A; Labetalol

One of the relatively unknow and fortunately benign side effect of beta-blockers is hyperkalemia. Most of the hyperkalemia is benign particularly with cardio-selective b-blockers. But life-threatening hyperkalemia may occur after IV dose of labetalol, particularly in patients with chronic renal failure, hemodialysis patients and post kidney transplant patients.


References: click to get abstract / article

1. Labetalol-Induced Hyperkalemia in Renal Transplant Recipients , American Journal of Nephrology 2002;22:347-351

2. Possible Metoprolol-Induced Hyperkalemia, Journal of Pharmacy Practice, Vol. 19, No. 5, 320-325 (2006)

Wednesday January 9, 2008


Q; Which 2 very commonly used medicines, physicians prescribe simultaneously and probably reflexly - but they cancel each other effects ?


A; β-blockers and Dobutamine (while trying to control tachycardia of dobutamine by b-blockers)

Dobutamine is a selective β1 adrenergic agonist and its effect get neutralize by β-blockers.

Atenolol, Esmolol, Metoprolol are β1 blockers
Carvedilol, Labetalol and Nadolol are β1, β2 blockers

Tuesday January 8, 2008
VATS conversion to a standard thoracotomy


Q; In how many cases VATS (Video-Assisted Thoracic Surgery)require intraoperative conversion to a standard thoracotomy ?

A; In approximately 20% of patients undergoing VATS, intraoperative conversion to a standard thoracotomy will be necessary for any of several reasons, including extensive pleural adhesions and pulmonary lesions that cannot be located thoracoscopically or that necessitate a more extensive resection than can be accomplished endosurgically.

(so keep fingers cross once you send your patient to OR)

Monday January 7, 2008
Mucomyst - does it work ? - yes, no, yes, no ?
Helps kidney or lung or liver ?

Since landmark 2000 article of NEJM 1 on benefit of antioxidant, N-acetylcysteine (mucomyst) on prevention of acute renal failure in many clinically stress situations, it has almost became a standard of practice. Since than though many studies failed to show its benefit and strictly from evidence based medicine, it has yet to prove its role !

This month, another study published from Italy in Critical Care Medicine 2, on benefit of N-acetylcysteine for prevention of acute renal failure in patients with chronic renal insufficiency undergoing cardiac surgery.

Randomized, placebo-controlled, prospective study of 254 consecutive patients with chronic renal insufficiency (estimated cr. cl. less than or = 60 mL/min) undergoing elective cardiac surgery wwas done. Patients were randomized into 2 groups

• to receive N-acetylcysteine (n = 129). Patients of the N-acetylcysteine group received four boluses of intravenous N-acetylcysteine (1200 mg every 12 hrs, starting immediately before cardiac surgery).
• or placebo (n = 125)

Postoperative acute renal failure is defined as more than 25% increase in serum creatinine from baseline.


Results:

• Acute renal failure occurred in occurred in 52% of control patients and 40% of N-acetylcysteine-treated patients (p = .06)
• In-hospital mortality and need for renal replacement therapy were not affected by N-acetylcysteine
• N-acetylcysteine-treated patients required less days of mechanical ventilation prolonged for >48 hrs (3% vs. 18%; p < .001)
• N-acetylcysteine-treated patients had lower incidence of prolonged stay in intensive care unit stay, defined as more than 4 days (13% vs. 33%; p < .001)

Conclusions:

Though IV mucomust does not clearly prevent postoperative acute renal failure in patients with renal insufficiency undergoing cardiac surgery, it suggests a positive effect of NAC on pulmonary function that influences a patient's clinical course by having lower days of mechanical ventilation and so lower ICU-LOS !

Editors' comment: Use it !


Related previous pearls:

Double the dose of mucomyst? ,
Contrast induced Nephropathy and
Preventing contrast-Induced Nephropathy - use of sodium bicarbonate



References: click to get abstract / article

1. Prevention of Radiographic-Contrast-Agent–Induced Reductions in Renal Function by Acetylcysteine - N Engl J Med 343:180, July 20, 2000
2. N-acetylcysteine for prevention of acute renal failure in patients with chronic renal insufficiency undergoing cardiac surgery: A prospective, randomized, clinical trial - Critical Care Medicine. 36(1):81-86, January 2008

Sunday January 6, 2008
Levaquin dosing in renal failure

Q; What's the dose adjustment of Levaquin (levofloxacin) in Hemodialysis or Chronic Ambulatory Peritoneal Dialysis (CAPD) as well as CVVHD patients?


A; For Hemodialysis, CAPD and with creatinine clearance less than 20 mL/min, dose of levofloxacin is 250 mg per 48 hours. In HD patients, dose should be given after HD session.

For CVVHD levaquin should be given as 250 mg/day as there is some clearance via CVVHD.


References: click to get abstract / article

1. Levaquin - Rxlist.com
2. Pharmacokinetics of Levofloxacin and Ciprofloxacin during Continuous - Renal Replacement Therapy in Critically Ill Patients (pdf) - ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Oct. 2001, p. 2949–295

Saturday January 5, 2008
Ok to fresh frozen plasma but male-donor-only please !!

In July 2003 the English Blood Service stopped using female donor plasma for the manufacture of fresh frozen plasma (FFP). Transfusion-related acute lung injury (TRALI), due to plasma from female donors containing antileucocyte antibodies, is allegedly a contributor to the development of acute lung injury (ALI). To confirm above hypothesis, a before-and-after, observational (single-centre) study was performed on 211 consecutive patients undergoing open repair of a ruptured AAA over 8 years period (1998 to 2006).

Primary outcome was development of ALI (PaO2/FiO2 < color="#003333">Secondary outcomes were time to extubation, and survival at 30 days.


Results
Primary outcome: There was significantly less ALI following the change to male-only FFP (36% before vs 21% after, P = 0.042). Secondary outcomes: were not statistically different between groups.

Patients with ALI in either group had a poorer 30-day survival (59% vs 80%, P = 0.005).

Conclusion:

Exclusion of female-donor FFP was associated with a statistically significant reduction in the incidence of ALI (in patients undergoing repair of a ruptured AAA).

Reference: click to get abstract / article

1. The effect of male-donor-only fresh frozen plasma on the incidence of acute lung injury following ruptured abdominal aortic aneurysm repair - Freeman Hospital and National Blood Service, Newcastle upon Tyne, UK - from 27th International Symposium on Intensive Care and Emergency Medicine Brussels, Belgium. 27–30 March 2007, Critical Care 2007, 11(Suppl 2):P374

Friday January 4, 2008
5 things to eye ball on TEG (Thromboelastogram)

Please also see our previous pearl What is TEG

Read with diagram below along with normal values

r - reaction time - from start of test to initial clot formation. Prolonged with clotting factor deficiencies and heparin.

a - Ang or alpha angle - it assesses rate of clot formation and decreased in the presence of clotting factor deficiencies, platelet dysfunction, thrombocytopenia, and hypofibrinogenaemia.

K - is a measure of time from beginning of clot formation until the amplitude of thromboelastogram reaches 20 mm, and represents the dynamics of clot formation.

MA - maximum amplitude - the widest point of the traceing on vertical or Y-axis . It represents maximum clot strength and is reduced with platelet dysfunction.

LY 30 or lysis 30 - is the percentage decrease in amplitude 30 min after MA, measures the degree of fibrinolysis. (see bending curves in b below)

References: click to get abstract / article

1. Thromboelastography / Thromboelastometry (pdf file) (ref: Clin. Lab. Haem. 2005, 27, 81–90)

2. Management of coagulation during cardiopulmonary bypass (pdf file) (ref: Continuing Education in Anaesthesia, Critical Care & Pain Volume 7 Number 6 2007)

Thursday January 3, 2008
Anticoagulation Medications - sites of action

A very simple diagram to show at what level basic 4 groups of anticoagulation medicines strike their effect.


Heparins - UFH and LMWH - are antithrombin

Warfarin - Warfarin inhibits the synthesis of biologically-active forms of the vitamin K-dependent clotting factors II, VII, IX and X, as well as the regulatory factors protein C, protein S, and protein Z.

Direct thrombin inhibitors (DTIs) - Hirudin, Lepirudin, Bivalirudin, Argatroban etc. - are a new class of anticoagulants that bind directly to thrombin and block its interaction with its substrates.

Thrombolytics - streptokinase, urokinase, alteplase, rtPA, reteplase, tenecteplase - works by activating the enzyme plasminogen, which clears the cross-linked fibrin mesh.

Wednesday January 2, 2008
Procedure video - Proper opening of mouth for intubation

Tuesday January 1, 2008