icuroom.net December 2008 Archive

2008-12-31T20:22:00.000-08:00

Wednesday December 31, 2008
On pleural effusion

Q: What are the usual clues on chest X-ray to suggest subpulmonic effusions?

Answer: Following few suggests subpulmonic effusions.
Apparent elevation of the hemidiaphragm,
lateral displacement of the dome of the diaphragm,
increased distance between the apparent left hemidiaphragm and the gastric air bubble

Lateral decubitus films more reliably detect smaller pleural effusions. Failure of an effusion to layer on lateral decubitus films indicates loculated pleural fluid or some other etiology causing the increased pleural density.

The film on the left at first glance doesn't appear to show fluid in the pleural space. The right hemidiaphragm is elevated, and if one looks carefully there is blunting of the right const-phrenic sulcus. Is there fluid in the pleural space? With the patient imaged with their right side down (B), fluid flows by gravity out from under the diaphragm and layers along the chest wall.

2008-12-30T07:18:00.000-08:00

Tuesday December 30, 2008
Is Xigris safe with anticoagulation of CVVHD?

Drotrecogin alfa is use for the treatment of severe sepsis with multiple organ failure. Patients with severe sepsis on renal replacement therapy (RRT), who typically receive additional anticoagulation to prevent circuit clotting, may be at higher risk of bleeding. The aim of this study was to analyse the filter survival time (FST), and to quantify the requirement of packed red cells (PRC) and blood products during xigris infusion.

Methods: This was a single-centre, retrospective observational study conducted in an adult intensive care unit (ICU). Thirty-five patients with severe sepsis who had received both RRT and Drotrecogin alfa were identified.

Results

The proportion of filter changes due to filter clotting was similar during Drotrecogin alfa infusion and with conventional anticoagulation Drotrecogin alfa infusion. There was no difference in the Filter survival time(FST) and filter parameters during Drotrecogin alfa in the presence or absence of additional anticoagulation with heparin or epoprostenol.
A similar proportion of patients required red cell transfusion, although a greater proportion of patients received platelet and fresh frozen plasma (FFP) during Drotrecogin alfa infusion compared to the Drotrecogin alfa period with no difference between medical and surgical patients.

Conclusions: Additional anticoagulation during Drotrecogin alfa infusion does not appear to improve Filter Survival Time (FST). The use of Drotrecogin alfa in patients with severe sepsis requiring RRT is safe and is not associated with an increased need for PRC transfusion or major bleeding events.

Reference: click to get abstract

Filter survival time and blood products requirement in patients with severe sepsis receiving drotrecogin alfa (activated) and requiring renal replacement therapy Critical Care 2008, 12:R163 (18 December 2008)

2008-12-29T10:51:00.000-08:00

Monday December 29, 2008
Sleepy residents: Are they sleepy in ICU

Recent study by Reddy and Surani * help to explore it further. The purpose of this study was to provide an objective assessment of daytime sleepiness in medical residents working in the medical ICUs. Sleep times for 2 days/nights prior to call and on the day/night of on-call were assessed by actigraphy and sleep diaries. On-call and post-call measurements of residents’ sleepiness were measured both objectively, by means of a modified MSLT (2 nap sessions), as well as subjectively, by Stanford Sleepiness Scale.

Results: Showed that despite an average sleep time of 7.15 h on nights leading to the call, Mean Sleep Latency (MSL) on the on-call day was 9 +/– 4.4 min compared to the MSL on the post call day of 4.8 +/–4.1 min. On the post-call day 14 residents (70%) had MSL values less than 5 min suggesting severe sleepiness as compared to 6 (30%) on the on-call day.

Conclusion: Results demonstrate that residents working in the ICU despite reductions in work hours demonstrate severe degree of sleepiness post-call.

Editorial comment: IOM recently came up with the suggestion to decrease the continuous straight work hour to 16 hrs, and if to go for 30 hrs then between 10 pm and 8 am, the resident should be given a break of 5 uninterrupted hours free of any duty or call.

* Dr. Surani is one of the co-editor for this website. We congratulate him on publication of his new paper.

Reference: click to get abstract

Reddy R, Guntupalli K, Surani S, Alapat P, Subramanian S. Sleepiness in Medical intensive care unit residents. Chest online first Nov 18. Chest, doi:10.1378/chest.08-0821

2008-12-28T19:08:00.000-08:00

Sunday December 28, 2008

Scenario: 48 year old male, hemodialysis dependent, admitted with gastro-intestinal bleed. Last dialysis was 3 days ago. Patient received 4 units of pRBC and now hemodynamically stable. Nurse calls you as she felt that rhythm looks different on monitor. Patient is asymptomatic. Walking towards patient's bed what would be your top diagnosis ?

Answer: Hyperkalemia

Transfusion-associated hyperkalemia is a potential life threatening condition in patients with renal failure who have not been dialysed recently or with already elevated/borderline potassium level and should be followed closely.

2008-12-27T18:36:00.001-08:00

Sunday December 27, 2008
If there is bleeding with LMWH

If protamine is given within 4 hours of the enoxaparin (Low Molecular Weight Heparins - LMWH), then a neutralizing dose is: 1 mg of protamine per 1 mg of enoxaparin. The IV protamine should be administered slowly atleast over 10 minutes as rapid infusion may cause anaphylactoid type reaction. May repeat half of earlier dose of protamine after 6 hours with postulation that half life of enoxaparin is longer than protamine.

LMWH, dalteparin (Fragmin) appears to be more responsive to protamine reversal.2 bonus pearls1. Protamine does not help in reversing bleeding from Fondaparinux (Arixtra). Only supportive treatment should be given with mean half-life of fondaparinux of 17-21 hours in mind.2. Fresh frozen plasma is ineffective in reversal of LMWH to achieve hemostasis and should not be use in these situations.

References: Click to get article/abstract

1. Accidental overdosage following administration of Lovenox - rxlist.com
2. Incomplete Reversal of Enoxaparin Toxicity by Protamine: Implications of Renal Insufficiency, Obesity, and Low Molecular Weight Heparin Sulfate Content - Obesity Surgery, Volume 14, Number 5, 1 May 2004, pp. 695-698(4)

2008-12-26T19:24:00.000-08:00

Saturday December 26, 2008
Hydroflouric acid exposure

Case: 23 year male while working in the refinery while disconnecting the hose was exposed to hydrofluoric acid. Patient had inhalation of hydrofluoric acid. Patient had no past medical history. Which of the following should be done first?

a. Albuterol nebulizer with 2.5 mg albuterol
b. Albuterol nebulizer with 10mg albuterol
c. Calcium gluconate nebulizer treatment
d. 10% mucomyst treatment

Answer : C

Calcium gluconate should be used after hydrofluoric acid exposure, and if there are any skin lesions it should be applied there too. Patient should be observed for 24-48 for development of pulmonary edema. Ionized calcium should be monitored very closely, and should be supplemented with intravenous calcium gluconate if low.

2008-12-25T17:24:00.000-08:00

Merry Christmas 2008
Santa Claus - A classic movie of its time in 1898

2008-12-24T18:54:00.000-08:00

Wednesday December 24, 2008
How much FFP?

Dr. Sam Schulman from Karolinska Hospital, Stockholm, Sweden wrote an excellent review on "Care of Patients Receiving Long-Term Anticoagulant Therapy" in August 14, 2003 issue of NEJM. Part of article suggest formula for amount of FFP (Fresh Frozen Plasma) to correct INR upto desired level in a bleeding patient from over-anticoagulation.

Amount of FFP needed(ml) =(target level as percentage - present level as percentage) x Wt.(kg)

The "percentage" is prothrombin complex, expressed as a percentage of normal plasma, corresponds to the mean level of the vitamin K–dependent coagulation factors. It can be compute easily with following table:

INR 1 = 100 (%)
INR 1.4 - 1.6 = 40
INR 1.7 - 1.8 = 30
INR 1.9 - 2.1 = 25
INR 2.2 - 2.5 = 20
INR 2.6 - 3.2 = 15
INR 4.0 - 4.9 = 10
INR > 5 = 5 (%)

Example: In a 70 kg patient bleeding with INR of 7.5 and if our target is to bring INR down to 1.4, using above table:

Total FFP needed = (40 - 5) x 70 = 2450 ml

(One unit FFP usually contains 200-250 ml of FFP)

Reference: click to get reference

Care of Patients Receiving Long-Term Anticoagulant Therapy - NEJM - Volume 349:675-683, August 14, 2003

2008-12-23T19:24:00.000-08:00

Tuesday December 23, 2008
Revisiting Pulmonary Artery Diastolic-Pulmonary Wedge Pressure Gradient

We don't see floatation of pulmonary artery catheter (PAC) as much as we used to see. Lets revisit one important but forgotten value obtained via PAC.

PADP - PAOP
(Pulmonary Artery Diastolic-Pulmonary Wedge Pressure Gradient)

Most of the literature in regards to this value is 15-30 years old but proven to be very easy to calculate but very vital to follow 1, 3.Once this gradient starts to exceeds by 6 mm Hg or more, the patient has shown to have a much poorer prognosis particularly in septic patients. Probable explanation is pulmonary venous vasoconstriction induced by endotoxemia in sepsis or postcapillary lekocyte aggregation in development of ARDS 2, 4.

One study suggests that although an initial PAD-PWP gradient in patients with sepsis is associated with a high mortality, a much more sensitive indicator is to follow the trend. There was a 91% mortality in patients with persisting or increasing gradients 2.

References: click to get abstract/artice

1. Pulmonary hypertension in sepsis: Measurement by the pulmonary arterial Diastolic-pulmonary wedge pressure gradient and the influence of passive and active factors. Chest 1978; 73:583-91

2. Significance of the pulmonary artery diastolic-pulmonary wedge pressure gradient in sepsis. Crit Care Med 1982; 10:658-61

3. Pulmonary artery diastolic and wedge pressure relationships in critically and injured patients. Arch Surg 1988; 123:933-6

4. Increased Pulmonary Venous Resistance Contributes to Increased Pulmonary Artery Diastolic-Pulmonary Wedge Pressure Gradient in Acute Respiratory Distress Syndrome - Anesthesiology: Volume 102(3) March 2005 pp 574-580 .

2008-12-22T20:42:00.000-08:00

Monday December 22, 2008
Stacked breaths - complication of low tidal volume? - itself causing high tidal volume?

Very interesting study, published last month to determine frequency, risk factors, and volume of stacked breaths during low tidal volume ventilation for acute lung injury.

Rationale: Low tidal volume ventilation strategies for patients with respiratory failure from acute lung injury may lead to breath stacking and higher volumes than intended.

Design, Setting, and Patients: Prospective cohort study of mechanically ventilated patients with acute lung injury in a medical intensive care unit at an academic tertiary care hospital. Patients were ventilated with low tidal volumes using the ARDS Network protocol.

Continuous flow-time and pressure-time waveforms were recorded. The frequency, risk factors, and volume of stacked breaths were determined. Sedation depth was monitored using Richmond agitation sedation scale.

Results: 20 patients were enrolled and studied for a mean 3.3 +/- 1.7 days. The median (interquartile range) Richmond agitation sedation scale was -4 (-5, -3).

Stacked breaths occurred at a mean 2.3 +/- 3.5 per minute and resulted in median volumes of 10.1 mL/kg predicted body weight, which was 1.62 times the set tidal volume
Stacked breaths were significantly less common with higher set tidal volumes (relative risk 0.4 for 1 mL/kg predicted body weight increase in tidal volume)

Conclusion: Stacked breaths occur frequently in low tidal volume ventilation despite deep sedation and result in volumes substantially above the set tidal volume. Set tidal volume has a strong influence on frequency of stacked breaths.

Reference: click to get abstract

Excessive tidal volume from breath stacking during lung-protective ventilation for acute lung injury - Critical Care Medicine. 36(11):3019-3023, November 2008.

2008-12-21T07:44:00.001-08:00

Sunday December 21, 2008

Retrograde Wire Intubation

2008-12-20T09:11:00.000-08:00

Saturday December 20, 2008
Cardio-pulmonary arrest in cocaine overdose

Q: Why vasopressin is preferable over epinephrine in cardio-pulmonary arrest due to cocaine overdose?

Answer: Epinephrine like cocaine has alpha-adrenergic effects. Because of this similarity in the cardiovascular effects, the administration of epinephrine to a patient who arrests in a hyperadrenergic state has been like "pouring gasoline over fire."

Moreover, cocaine prevents the reuptake of exogenously administered epinephrine. Therefore, if epinephrine is used, AHA Guidelines recommends that high-dose epinephrine should be avoided and that the interval for its administration be increased (q 5-10min).

Vsopressin offer considerable advantages over epinephrine in cardiac arrest secondary to cocaine toxicity. The hyperadrenergic state caused by cocaine increases myocardial oxygen demand and vasopressin increases coronary blood flow, and thereby myocardial oxygen availablity.

Also, cocaine toxicity causes acidosis and epinephrine loses much of its effectiveness in an acidotic enviroment, whereas vasopressin demonstrates good efficacy even with severe acidosis.

2008-12-19T20:51:00.000-08:00

Friday December 19, 2008
Humidification during Mechanical Ventilation

Q: What is the desirable/optimum temperature for humidification to deliver at trachea during Mechanical Ventilation?

Answer: 33 ± 2°C

When the upper airway is bypassed, humidification during mechanical ventilation is necessary to prevent hypothermia, inspissation of airway secretions, destruction of airway epithelium, and atelectasis. This may be accomplished using either a heated humidifier or a heat and moisture exchanger (HME). The device should provide a minimum of 30 mg H2O/L of delivered gas at 33 ± 2°C.

High temperature alarm should be set no higher than 37°C, and the low temperature alarm should be set no lower than 30°C.

2008-12-18T15:56:00.000-08:00

Thursday December 18, 2008
Prothrombin Time for Detection of Contaminated Heparins

Editors' note: Interesting correspondence published this week in The New England Journal of Medicine. It is available as free text. Click on reference below to obtain authors and related references. We are reproducing few important parts.

"The recent "heparin scandal" resulted from the use of contaminated heparin that caused serious adverse events including death. The contaminant was identified as synthetically oversulfated chondroitin sulfate (OSCS). Despite the missing final proof of a cause-and-effect relationship, OSCS was shown to have pharmacologic effects that may contribute to the observed allergic-type reactions. Furthermore, OSCS is suspected to be responsible for an observed increased incidence of heparin-induced thrombocytopenia type 2. ...........

We report on the use of prothrombin time to detect OSCS contamination in both unfractionated heparin and low-molecular-weight heparins. As expected, only plasma concentrations of 5 µg per milliliter (about 1 IU per milliliter) or greater of unfractionated heparin and 10 µg per milliliter of unfractionated heparin contaminated with 17.4% OSCS (contaminated unfractionated heparin) slightly prolonged the prothrombin time (by 9% and 12%, respectively)........

Highly sulfated polysaccharides such as OSCS are known to act as anticoagulants, but they also induce contact activation promoting in vitro coagulation. However, with activated partial-thromboplastin time assays (also used for the assay of heparin in the U.S. and European pharmacopeias) in which the coagulation is initiated by contact activators, such effects cannot be recognized. In contrast, the prothrombin time is suitable for determining such procoagulant effects for two reasons. First, the coagulation is induced by thromboplastin. Second, the prothrombin time is quite insensitive to heparins, so that any procoagulant effect of OSCS is not obscured.

In conclusion, the prothrombin time could be used in a validated form as a sensitive screening test for the quality control of heparins. In clinical practice it could serve as a simple and fast assay to check the applied heparin when heparin-induced thrombocytopenia type 2 or allergic-type reactions develop in a patient who is receiving heparin..."

Reference: click to get abstract

Prothrombin Time for Detection of Contaminated Heparins - The New England Journal of Medicine, Volume 359:2732-2734, Number 25, December 18, 2008

2008-12-17T07:09:00.000-08:00

Wednesday December 17, 2008
Interesting case report - Acute Left Atrial Thrombus After rFactor VIIa Administration

Editors' note: As Factor 7 is getting more and more used in cinical practices, we think, this is an important case report to atleast have a look on. Our criticism on following case report is that - the amount of Factor 7 used was 'humongous'. Usually 1.2mg - 4.8 mg should be sufficient.

This is a case report of a patient with end-stage heart failure and heparin-induced thrombocytopenia Type II, who required cardiopulmonary bypass (CPB) during a repeat implantation of a left ventricular assist device for long-term circulatory support. Bivalirudin was selected for anticoagulation during CPB, with concomitant infusion of aprotinin, in an effort to ameliorate blood loss. Nonetheless, profuse bleeding after CPB required massive transfusion of packed red blood cells, multiple coagulation factors, and platelets. Because of persistent bleeding, a single dose of recombinant factor VIIa (rFVIIa, 7.2 mg) was administered as rescue therapy. Within minutes, a large left atrial thrombus was detected by transesophageal echocardiography. We believe this is the first documentation of acute left atrial thrombus formation immediately after a single dose of recombinant factor VIIa administration during a left ventricular assist device implantation.

Reference: click to get abstract

Acute Left Atrial Thrombus After Recombinant Factor VIIa Administration During Left Ventricular Assist Device Implantation in a Patient with Heparin-Induced Thrombocytopenia - Anesth Analg 2008; 106:404-408

2008-12-16T10:30:00.000-08:00

Tuesday December 16, 2008

Q: 58 year old male who underwent cardiac angiogram 3 weeks ago, now presented with acute renal failure. Another unexpected finding on blood workup is significant eosinophilia. On clincal exam following is noted but with good palpable pedal pulses. What is your diagnosis?

Answer: Cholesterol Emboli

Cholesterol embolism (CE) is occlusion of small- and medium-caliber arteries by cholesterol crystals. CE is often triggered by an invasive vascular procedure, administration of anticoagulants, local or systemic thrombolytic therapy, or trauma. These cause rupture of atheromatous plaques in proximal major arteries releasing cholesterol crystals into the bloodstream. The crystals migrate distally until they lodge in small arterioles, where they provoke an acute inflammatory response

2008-12-15T16:30:00.000-08:00

Monday December 15, 2008

Q: Whats the danger of being very close to inguinal ligament while putting femoral venous or arterial central line?

Answer: Possible development of retroperitoneal hematoma and decrease ability to compress the bleeding site. Retroperitoneal hematoma is a serious and potentially very fatal complication after femoral cannulation. High femoral puncture (particularly if accompanied by coagulopathy), increases the risk of hematoma formation. Its always wise to stay well below inguinal ligament (atleast 3-4 cm) so developing hematoma is visible and can be compressed.

2008-12-14T20:40:00.000-08:00

Sunday December 14, 2008

Case: While floating pulmonary artery catheter you have hard time measuring "wedge" (pulmonary artery occlusion pressure). After few attempts you noticed couple of blood drops in pulmonary artery catheter syringe. What does it mean and what should be you next step?

Answer: Pulmonary artery catheter balloon is rupture

When pulmonary artery catheter balloon is rupture, there could be two scenarios, either there is usually no resistance to balloon inflation or you may notice blood in the balloon port's tubing (syringe).

If there is suspicion of ballon rupture or blood in the balloon tubing,
IMMEDIATELY clamp off the port
Do not perform any PAOP/wedge measurement anymore
Lock the port, and
Tape over the port/syringe with a note "Balloon Busted"

Attempt to inject further air or to clear the blood may cause a potentially life-threatening air or blood clot emboli.

2008-12-13T06:11:00.000-08:00

Saturday December 13, 2008
ECMO life-support proved more efficient than conventional CPR

Extracorporeal life-support as an adjunct to cardiac resuscitation has shown encouraging outcomes in patients with cardiac arrest. However, there is little evidence about the benefit of the procedure compared with conventional cardiopulmonary resuscitation (CPR), especially when continued for more than 10 min. Study was aimed to assess whether extracorporeal CPR was better than conventional CPR for patients with in-hospital cardiac arrest of cardiac origin.

Methods: A 3-year prospective observational study on the use of extracorporeal life-support for patients aged 18—75 years with witnessed in-hospital cardiac arrest of cardiac origin undergoing CPR of more than 10 min compared with patients receiving conventional CPR. Of the 975 patients with in-hospital cardiac arrest events who underwent CPR for longer than 10 min, 113 were enrolled in the conventional CPR group and 59 were enrolled in the extracorporeal CPR group.

The primary endpoint was survival to hospital discharge.

Results:
Unmatched patients who underwent extracorporeal CPR had a higher survival rate to discharge and a better 1-year survival than those who received conventional CPR
Between the propensity-score matched groups, there was still a significant difference in survival to discharge, 30-day survival and 1-year survival favouring extracorporeal CPR over conventional CPR.
82 percent of cardiac arrest patients who owed their survival to ECMO procedure returned to work within one year.

Conclusion: Extracorporeal CPR had a short-term and long-term survival benefit over conventional CPR in patients with in-hospital cardiac arrest of cardiac origin.

Reference: click to get abstract

Cardiopulmonary resuscitation with assisted extracorporeal life-support versus conventional cardiopulmonary resuscitation in adults with in-hospital cardiac arrest: an observational study and propensity analysis - The Lancet, Volume 372, Issue 9638, Pages 554 - 561, 16 August 2008

2008-12-12T12:46:00.001-08:00

Friday December 12, 2008

Q: Following of which is the immediate drug of choice to treat ventricular tachycardia (V.Tach.) induced from Digitalis toxicity? - choose one

A) B- blocker
B) Calcium Channel Blocker
C) Amiodarone
D) Phenytoin
E) Quinidine

Answer: Phenytoin

Actually - Beta-blocker, Calcium Channel Blocker, Quindine and Amiodarone should be avoided in Digitalis induced ventricular tachyarrhythmias as they may exacerbate it.

In above situation either Phenytoin or Lidocaine should be the drug of treatment.

2008-12-11T14:18:00.001-08:00

Thursday December 11, 2008

Q: Ibutilide is a type III antiarrhythmic agent approved for the pharmacologic conversion of atrial fibrillation and atrial flutter. Conversion rates is described upto 80% of cases. What is the half-life of Ibutalide?

A: 4 hours

Ibutilide (Corvert) is a Class III antiarrhythmic agent that is indicated for acute cardioconversion of atrial fibrillation and atrial flutter of a recent onset to sinus rhythm. Due to unknown reason, It show better results in atrial flutter as compared to atrial fibrillation.

Ibutalide should be use with caution as it may degenrate rhythm into sustained Torsade (polymorphic ventricular tachycardia) in 3% of cases. Also due to longer half life, its not recommended to repeat dose more than twice as it may take upto 90 minutes before normal sinus rhythm gets restored.

Dose is usually 1 mg over 10 minutes (may repeat once) but in post-cardiac surgery patients, one or two infusions of 0.5 mg is usually effective in terminating atrial fibrillation or atrial flutter.

2008-12-10T15:32:00.000-08:00

Wednesday December 10, 2008
Regarding Low SVR state following off-pump CABG

Study was done to determine the prevalence, hemodynamic characteristics, and risk factors for low systemic vascular resistance (SVR) state following after off-pump coronary artery bypass (OPCAB).

PATIENTS AND METHODS: SVR data could be obtained for 116 OPCAB patients. Low SVR was defined as an indexed systemic vascular resistance (SVRi) of less than1,800 dyne x s/cm(5) x m(2) at the end of operation.

Hemodynamic data were recorded preoperatively, at the end of operation, just after entering ICU, and the following morning.

RESULTS: Low SVR state was noted in 54 of 116 patients (53%). The SVRi values in low-SVR and non-low-SVR patients were 1,406+/-253 and 2,326+/-509 dyne x s/cm(5) x m(2) at the end of operation.
Increased CI level, decreased MAP level, but unchanged CVP level was observed postoperatively in the low-SVR patients. The increase in CI and decrease in MAP were maximal at the end of operation.
Patients with low SVR were more likely to have a higher body mass index and to be male than no-low-SVR patients.
In low-SVR patients, fluid balance was more positive intraoperatively but more negative at 6 hours postoperatively and 12 h postoperatively

CONCLUSIONS: Low SVR state, a probable manifestation of systemic inflammatory response (SIRS), is common in patients who have undergone OPCAB. For these patients it is more reasonable to maintain MAP with vasopressors by restoring vascular tone, than by volume loading.

Reference: click to get article

Ann Thorac Cardiovasc Surg. 2008 Feb;14(1):15-21

2008-12-09T10:08:00.000-08:00

Tuesday December 9, 2008

Q: 52 year old male with history of End Stage Renal Disease (ESRD) - is admitted at 12 midnight with fluid overload, hypertensive crisis and mild hyperkalemia after he missed his dialysis session. Patient required intubation for hypoxemia but now saturating 100% on ventilator. Nephrology service informed you that it will take atleast 4 hours before hemodialysis can be arranged. Why Labetolol would be a bad choice for control of hypertension?

A: Labetolol may make hyperkalemia worse

Intravenous labetolol, a nonselective α- and β-blocking drug, is commonly used to treat severe hypertension but it can cause hyperkalemia. In patients with renal failure, it can be life-threatening, particularly in situations where emergent hemodialysis is not available.

Reference:

Life-Threatening Hyperkalemia after Intravenous Labetolol Injection for Hypertensive Emergency in a Hemodialysis Patient - Am J Nephrol 2001;21:241-244

2008-12-08T06:59:00.000-08:00

Monday December 8, 2008

Q: 56 year old male is intubated in ICU with COPD exacerbation. In last one hour there are frequent "vent. alarms" but silenced by bedside staff. Patient now went into PEA (pulseless electrical activity). RT disconnected patient from ventilator but even before bagging is resumed, patient recovered good pulse and blood pressure?

A: Auto-PEEP induced PEA

Elevated end-expiratory pressure ("auto-PEEP") decreases venous return and may depress cardiac output. Transient withdrawal of ventilation allows the dynamic hyperinflation to be lessened, reducing intrathoracic pressure and permitting the return of spontaneous circulation. On the same token, it is important to avoid aggressive bagging during cardiopulmonary resuscitation.

Reference: click to get article

Auto-PEEP and Electromechanical Dissociation - Volume 335:674-675, Number 9, August 29,1996, NEJM

2008-12-07T13:42:00.000-08:00

Sunday December 7, 2008

Q: 36 year old male with history of pulmonary hypertension is admitted to ICU with shortness of breath. List of medication includes Revatio. What is Revatio?

A: Revatio is another trade name for Sildenafil (Viagra). The white, round pills looks different from Viagra's blue diamond shape. This is to avoid embarassment for patients with pulmonary hypertension, if they present to pharmacy with Sildenafil prescription. Moreover, it helps to avoid confusion in medical history part.

2008-12-06T12:32:00.000-08:00

Saturday December 6, 2008
Dosing of Esmolol

Q: How much time does it take for esmolol to reach steady-state blood levels, if you don't use loading dose for esmolol infusion?

A: Using an appropriate loading dose, steady-state blood levels of Esmolol for dosages from 50-300 mcg/kg/min (0.05-0.3 mg/kg/min) are obtained within 5 minutes, otherwise it takes 30 minutes to reach steady-state without the loading dose. Steady-state blood levels of Esmolol increase linearly over this dosage range and elimination kinetics are dose-independent over this range.

Esmolol dosing guideline:

An initial loading dose of 0.5 milligrams/kg (500 micrograms/kg) infused over a minute duration followed by a maintenance infusion of 0.05 milligrams/kg/min (50 micrograms/kg/min) for the next 4 minutes is recommended. This should give a rough guide with respect to the responsiveness of ventricular rate.

After the 4 minutes of initial maintenance infusion (total treatment duration being 5 minutes), depending upon the desired ventricular response, the maintenance infusion may be continued at 0.05 mg/kg/min or increased step-wise (e.g. 0.1 mg/kg/min, 0.15 mg/kg/min to a maximum of 0.2 mg/kg/min) with each step being maintained for 4 or more minutes.

If more rapid slowing of ventricular response is imperative, the 0.5 mg/kg loading dose infused over a 1 minute period may be repeated, followed by a maintenance infusion of 0.1 mg/kg/min for 4 minutes. Then, depending upon ventricular rate, another (and final) loading dose of 0.5 mg/kg/min infused over a 1 minute period may be administered followed by a maintenance infusion of 0.15 mg/kg/min. If needed, after 4 minutes of the 0.15 mg/kg/min maintenance infusion, the maintenance infusion may be increased to a maximum of 0.2 mg/kg/min.

In the absence of loading doses, constant infusion of a single concentration of esmolol reaches pharmacokinetic and pharmacodynamic steady-state in about 30 minutes. Maintenance infusions (with or without loading doses) may be continued for as long as 24 hour.

Esmolol (Brevibloc) - rxlist.com

2008-12-05T20:06:00.001-08:00

Friday December 5, 2008
Is Traditional Reading of the Bedside Chest Radiograph Appropriate To Detect Intraatrial Central Venous Catheter Position?

Background:Traditionally, the positioning of central venous catheters (CVCs) outside the right atrium (RA) in patients receiving intensive care is determined by surrogate landmarks on bedside chest radiographs (CXRs). The validity of this method was examined by comparing readings of radiologists with the results of transesophageal echocardiography (TEE).

Methods: Prospective study at university hospital. Two hundred thirteen adults scheduled for cardiothoracic surgery were randomized to right or left internal jugular vein catheterization under ECG guidance. One senior radiologist and two radiologists in training independently read the CXRs, and determined whether the CVC tip ended in the RA and measured the vertical distance from the CVC tip to the carina (TC-distance).

Results:Two hundred twelve CVC tips could be identified by TEE. Only left-sided CVCs (n = 5) ended in the upper RA (2.4%). Three of those patients were shorter than 160 cm. Specificity was 94% for senior radiologist, 44% for the first radiologist in training, and 60% for the second radiologist in training. The TC-distance of intraatrial catheters was 39, 55, 59, 80, and 83 mm, respectively. Thus, a TC-distance 55 mm ensured extraatrial tip position in four of five intraatrial CVCs (80%, p = 0.002). The TC-distance of extraatrial catheters ranged from – 26 to 102 mm.

Conclusions: Reading of a bedside CXR alone is not very accurate to identify intraatrial CVC tip position. TC-distance is a helpful marker, and its specificity is as good as that of an experienced radiologist if a cutoff value of 55 mm is chosen.

Reference: click to get article

Is Traditional Reading of the Bedside Chest Radiograph Appropriate To Detect Intraatrial Central Venous Catheter Position? - Chest. 2008; 134:527-533

2008-12-04T06:27:00.000-08:00

Thursday December 4, 2008
Artificial intelligence in ICU !!

A very interesting study - "An artificial intelligence tool to predict fluid requirement in the intensive care unit: a proof-of-concept study" - is just published at ccforum.com

An alternative way of personalizing medicine in the ICU on a realtime basis by using information derived from the application of artificial intelligence on a high resolution database, is proposed. Calculation of maintenance fluid requirement at the height of systemic inflammatory response was selected to investigate the feasibility of this approach.

The Multi-parameter Intelligent Monitoring for Intensive Care II (MIMIC II) is a database of patients admitted to the Beth Israel Deaconess Medical Center ICU.

METHOD: Patients who were on vasopressors for more than 6 hours during the first 24 hours of admission were identified from the database. Demographic and physiologic variables that might affect fluid requirement or reflect the intravascular volume during the first 24 hours in the ICU were extracted from the database. The outcome to be predicted is the total amount of fluid given during the second 24 hours in the ICU, including all the fluid boluses administered.

Investigators represented the variables by learning a Bayesian network from the underlying data. Using ten-fold cross-validation repeated 100 times, the accuracy of the model in predicting the outcome is 77.8%. The network generated has a threshold Bayes factor of 7 representing the posterior probability of the model given the observed data. This Bayes factor translates into p < .05 assuming Gaussian distribution of the variables.

Conclusions: Based on the model, the probability that a patient will require a certain range of fluid on day 2 can be predicted. In the presence of a larger database, analysis may be limited to patients with identical clinical presentation, demographic factors, co-morbidities, current physiologic data, and those who did not develop complications as a result of fluid administration. By better predicting maintenance fluid requirements based on the previous day's physiologic variables, one might be able to prevent hypotensive episodes requiring fluid boluses during the course of the following day.

Reference: click to get article

An artificial intelligence tool to predict fluid requirement in the intensive care unit: a proof-of-concept study - Critical Care 2008, 12:R151 - pdf file

2008-12-03T11:17:00.000-08:00

Wednesday December 3, 2008
Sodium retention in Corticosteroids

Q; Which Corticosteroid has highest Relative Sodium Retension (RSR)?
- Choose one

A) Prednisone
B) Methylprednisone
C) Hydrocortisone
D) Dexamethasone

Answer: Hydrocortisone

Hydrocortisone has Relative Sodium Retention of "20" in comaprison to other steroids

Prednisone's RSR is 1

Methylprednisone RSR is 0.5

Dexamethasone RSR is 0

2008-12-02T10:46:00.000-08:00

Tuesday December 2, 2008
Hepatic Hydrothorax

Q; How you confirm the cause of pleural effusion (mostly right sided) in cirrhotic patient as hepatic hydrothorax?

Answer: By radioisotope imaging (nuclear medicine)

Pleural effusion in cirrhotic patients (hepatic hydrothorax) may result from migration of ascitic fluid across defects in the diaphragm. Biochemical analysis of ascitic and pleural fluid provides only indirect information about the nature and origin of the effusion.

Transdiaphragmatic movement of ascitic fluid into the pleural space can be demonstrated, generally within 2 hours of intraperitoneal injection of the radiotracer ( 99mTc sulfur colloid scintigraphy).

Radionuclide scintigraphy is a simple, safe and relatively non-invasive method to confirm passage of ascitic fluid across the diaphragm.

2008-12-01T12:08:00.000-08:00

Monday December 1, 2008

Life Cycle of Malaria (still image below)