Tuesday October 31, 2006
Bench to Bedside !!

Hyperchloremic acidosis is common in ICU patients secondary to IVF boluses with 0.9 NS and usually get ignored unless it becomes critical as we all take it as a benign phenomenon. But is it?

Dr. John A. Kellum and coll. from the MANTRA Laboratory, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA looked into the magnitude of hyperchloremic acidosis with target choosen in investigation near clinical scenarios. They induced lethal sepsis in 20 adult rats and were randomized into three groups.

• In group 1 lactated Ringer solution was given.
• In group 2 an IV infusion of 0.1 N HCl given to reduce the standard base excess (SBE) by 5 to 10 mEq/L.
• In group 3 an IV infusion of 0.1 N HCl given to reduce the standard base excess (SBE) by 10 to 15 mEq/L.

In all groups infusion continued for 8 h or until the animal died. ABGs, lactate, chloride, TNF, interleukin (IL)-6, and IL-10 levels were measured at 0, 4 and 8 h. Compared to group 1, animals in groups 2 and 3 exhibited greater increase in all three cytokines, with the greatest increases seen with severe acidosis. Study concluded that hyperchloremic acidosis, induced by dilute Hcl infusion, significantly increased cytokine expression in a dose-dependent fashion.


Clinical significance / Editors' note: In camparison to surgical ICUs, medical ICUs are more inclined to use 0.9 NS which carries significantly higher content of chloride. In many instances, either LR or Normosol may be a better choice with low chloride content but still isotonic in nature. See related previous pearls below.

Difference between Lactate Ringer's and Normal Saline solutions

Normosol is NOT just Normal Saline



Reference: click to get abstract

Hyperchloremic Acidosis Increases Circulating Inflammatory Molecules in Experimental Sepsis - Chest. 2006;130:962-967

October 30, 2006
Light Wand !!


Frequently we try to post different tips and available tools on procedures. As we talked before, orotracheal intubation remained one of the most essential but could be the most frustrating procedure in ICU. Different tools have been developed in this regard. Out of those one technique is illuminated stylet (trade name 'light wand' from Vital Signs, Inc).

Idea is to provide trans illuminated intubation. Bright light at tip of stylet provides excellent verification of positioning even during difficult intubations. Actually, blind intubation can be performed just with the guidance of light illuminating the skin above the thyroid cartilage as it enters the larynx (will not illuminate if it enter esophagus). You can perform intubation without neck movement or even without laryngoscope but only following light illumination with success rate reported around 95%. The commercial product promise of not rising the surface temperature of the ET Tubeabove 42 C. Also it doesn't require battery but the life of illumination is 3 hours.

The only limitation is obese neck.


Related Previous Pearls:

Airtraq , How many attempts to intubate?


Note: icuroom.net has no financial relationship with any company. Info provided here is 100% for educational purpose.

Sunday October 29, 2006
Bedside tip

Beauty of Critical Care lies in details. One very important but mostly ignored tip given by Dr. Marini. "........once the patient is extubated, remove the ventilator from the room if safe to do so, when not connected to the patient, the ventilator offers little more than expensive psychological comfort. Many hospitals charge ventilator fees in 12-hour blocks, and if the ventilator is still in the room, the patient will be charged for unneeded equipment.."

How many of us have thought of this ?


Reference:
Critical Care Medicine - 3rd edition - Marini & Wheeler - Page 318.

Saturday October 28, 2006
Bedside tips


Q: Which poison smell's like "Almond"?
A: Cyanide


And which poisoning presents with garlic odor?
A: Organophosphate poisoning

Friday October 27, 2006
Unplanned extubations (UE)

Unplanned extubations in ICUs have been reported anywhere from 1-16% with higher incidence in surgical ICUs.

Unplanned extubations have been tagged as one of the "outcome measures" in famous article published earlier this year - "Intensive care unit quality improvement: A how-to guide for the interdisciplinary team" 1.


To improve the UE rate, one study was done at at St. Joseph’s Hospital in Marshfield, Wis., where a committee comprised of an intensivist, the respiratory therapy staff and the nursing staff looked into frequency of unplanned extubations in the adult ICUs during a 6-month period (see the incident report form in reference). After obtaining data, committee took 2 steps approach.

As a first step, the committee examined various endo-tracheal tube (ETT) holders available, looking at design, securability, ease of application, durability, ease to maintain the integrity of the oral mucosa and to maintain skin integrity beneath the area of application. After selecting the product, second step was taken and extensive in-service training sessions were done over 2 weeks spreading over all shifts for the nursing and the respiratory staff including right technique, taping, application of an adhesive skin preparation etc.

Rate of UE was compared 6 months preceding staff education with the 6 months after staff education. In the CCU/ MICU, the unplanned extubation rate decreased from 2.14% to 0.87% and in the SICU, the unplanned extubation rate decreased from 2.32% to 1.0% (10 extubations in 1000 days) after the education 2.


References: click to get abstract/article

1. Intensive care unit quality improvement: A "how-to" guide for the interdisciplinary team - Critical Care Medicine. 34(1):211-218, January 2006
2. Unplanned Extubation in Adult Critical Care - Critical Care Nurse. 2004;24: 32-37
3. The Drive to Survive, Unplanned Extubation in the ICU - Chest. 2005;128:560-566

emThursday October 26, 2006
Neuromuscular blocking agents (NMBAs) in ARDS

We all dread and think twice before using NMBAs. But in this month (November 2006) of Critical Care Medicine 1, there is a prospective randomized trial of 36 patients published from france showing postive effect of neuromuscular blocking agents in patients presenting with acute respiratory distress syndrome.

A total of 36 patients with acute respiratory distress syndrome (Pao2/Fio2 ratio of less than / = 200 at a PEEP of more than/ = 5 cm H2O were included within 48 hrs of ARDS onset. Patients were randomized to receive

• conventional therapy plus placebo (n = 18) for 48 hrs or
• conventional therapy plus NMBAs (n = 18) for 48 hrs.

Both groups were ventilated with low tidal volume between 4 and 8 mL/kg.

Bronchoalveolar lavages and blood samples were performed, before randomization and at 48 hrs, to determine the concentrations of

• tumor necrosis factor-α,
• interleukin (IL)-1β,
• IL-6, and
• IL-8

Pao2/Fio2 ratio was evaluated before randomization and at 24, 48, 72, 96, and 120 hrs.


At 48 hrs after randomization, pulmonary concentrations of IL-1β, IL-6 and IL-8 were lower in the NMBA group as compared with the control group. Similar pattern noticed in serum samples. Importantly, a sustained improvement in Pao2/Fio2 ratio was observed in the NMBA group upto 120 hours.

Reference: click to get abstract
Neuromuscular blocking agents decrease inflammatory response in patients presenting with acute respiratory distress syndrome - Critical Care Medicine. 34(11):2749-2757, November 2006

Wednesday October 25, 2006
Re: Calcium Channel blocker overdose


Editors' note: In response to our pearl on Saturday October 21, 2006 regarding Calcium Channel Blocker overdose, we received following feedback which is worth sharing.


"...First, I want to congratulate you on a most excellent website. I always enjoy reading the daily pearls. The daily pearl for 10/21/06 is regarding CCB overdose and potential treatments with glucagon and amrinone. One very important treatment strategy for Beta-blocker (BB) or Calcium-Channel-Blocker (CCB) overdoses resistant to the above traditional antidotes is the use of hyperinsulin/euglycemia therapy. (I have personally used this on a propranolol overdose with much success). This is the treatment of the future and widely reccommended by the toxicology folks and should always be noted as a potential salvage therapy when the traditional approaches fail. I have attached 2 recommended readings 1, 2 regarding HDIDK (High Dose Insulin Dextrose Potassium) in regards to treatment of CCB and BB toxicity.

Thanks,
C Brackney, DO
St Bernards Hospital,Midwestern University / Chicago College of Osteopathic Medicine
Emergency Medicine Residency ProgramChicago, IL


As both attached references are from subscription journals, we put link to abstracts below but there is a free review available: Treatment of poisoning caused by ß-adrenergic and calcium-channel blockers , GREENE SHEPHERD, PHARM.D., DABAT, Clinical Associate Professor, Medical College of Georgia, Augusta, GA (reference: American Journal of Health-System Pharmacy, Vol. 63, Issue 19, 1828-1835)



Recommended Reading:

Treatment of Calcium-Channel–Blocker Intoxication with Insulin Infusion - The New England Journal of Medicine , May 31, 2001, Volume 344:1721-1722
High-Dose Insulin Therapy for Calcium-Channel Blocker Overdose - Shepherd and Klein-Schwartz Ann Pharmacother.2005; 39: 923-930

Tuesday October 24, 2006
CR-BSIs

One of the parameter or measurement of ICU is the decreasing rate of CR-BSIs. (Central line catheter-related bloodstream infections). CR-BSIs are calculated or presented usually per 1000 central line-days. The formula for the CR-BSI Rate per 1000 catheter days is:

Total no. of CR-BSI cases / No. of catheter days x 1000 = CR-BSI rate per 1000 catheter days


For example:

In a given month, you had 100 central lines in your ICU and each stayed there for 4 days. Your total no. of catheter days are 100 X 4 = 400 days. Now you confirmed 15 cases of CR-BSIs. The CR-BSI Rate per 1000 catheter days in your ICU for that given month is 15 / 400 x 1000 = 37.5

On average per IHI report approximately 5.3 catheter-related bloodstream infections occur per 1,000 catheter days in ICUs.

Now your goal should be to decrease this number for your ICU.


Bonus Pearl: As against common belief, application of ointment at catheter insertion site does not decrease the infection rate. Actually application of antibiotic ointments (e.g., bacitracin) to catheter-insertion sites increases the rate of catheter colonization by fungi and promotes the emergence of antibiotic-resistant bacteria.


Related Site: Implement the Central Line Bundle (IHI)


Recommended Reading:

Preventing Complications of Central Venous Catheterization, David C. McGee, M.D.,, NEJM, March 03, Volume 348:1123-1133.

Monday October 23, 2006
Hypotension in ED and Sudden Unexpected In-hospital Mortality !

Interesting study published this month in 'chest' though not sure how it impacts the overall management as editorial in the same issue asked: "But despite the strength of the observational data in this study, there is still one all-important question that will require additional research and remains as-of-yet unanswered: "now what should you DO?".

Nontrauma Emergency Department patients (age above 17) were divided into 2 groups:

• "Exposures" who had any systolic BP less than 100 mm Hg in the ED ( n = 887)
• "Non-exposures" all had SBP more than or equal to 100 mm Hg in the ED (n = 3903)

Deaths were classified as sudden and unexpected by independent observers (using explicit criteria - available in article).

'Exposures' were more likely to die in the hospital compared with nonexposures as well as 'Exposures' were more likely to have sudden and unexpected death compared with nonexposures (2% vs 0.2%). Exposure to hypotension was as an independent predictor of in-hospital mortality. Study concluded that patients exposed to hypotension (even single reading of less than 100 mm Hg) had a significantly increased risk of death during hospitalization, despite been stabalized later in ED or hospital.

As asked in the discussion of this study by authors and being an intensivist, here is the million dollar question?: "Do they need to get admit to higher level of care such as an ICUs?".


Reference: click to get abstract

Emergency Department Hypotension Predicts Sudden Unexpected In-hospital Mortality Chest. 2006;130:941-946.

Sunday October 22, 2006
Refractory hypokalemia in presence of hypomagnesemia


Q; Why potassium cannot be fixed if hypomagnesemia remains uncorrected?

A; Hypomagnesemia causes kidney to continue to loose potassium, thats why hypokalemia cannot be fixed if hypomagnesemia remains uncorrected. It can be confirmed with TTKG calculation.


Related previous pearl: TTKG

Saturday October 21, 2006
Calcium Channel blocker overdose


Q; Which 'Calcium Channel Blocker' overdose may not produce noticeable hypotension but severe heart blocks (and may decieve the diagnosis) ?

A; Diltiazem. Most of the CCB overdose produce significant hypotension as expected but Dilitiazem may decieve you by just producing heart blocks.


2 important pearls in treating CCB overdose beside calcium infusion and standard hemodynamic support.

1. 5 - 15 mg IV Glucagon is a viable adjuvant treatment in calcium channel bloker overdose. But it is advisible to administer Glucagon before calcium infusion is given, as erratic blood calcium level may mask full effect of glucagon. Glucagon via cAMP increases cardiac contractility and counter heart blocks.

2. Consider adding Inocor (amrinone) infusion. It is a Phosphodiesterase inhibitor and has 2 actions. 1) it delays release of calcium into the cell 2) it increases cardiac contractility via cAMP.

Friday October 20, 2006
High-volume hemofiltration as salvage therapy in severe hyperdynamic septic shock

There tend to be a continue interest in high-volume hemofiltration for sepsis and every now and then we see studies in respected journals. Overall, literature tends to favor high-volume hemofiltration as a salvage therapy in severe septic shock and if nothing is working, why not to use it as a last resort?

Recently one study of 20 patients published from Chile to evaluate the effect of short-term (12 hours) high-volume hemofiltration (HVHF) in reversing progressive refractory hypotension and hypoperfusion in patients with severe hyperdynamic septic shock unresponsive to traditional sepsis therapy.
11 of 20 patients were found to be "responders" with decrease in decreased norepinephrine dose, lactate levels and heart rates. Arterial pH improved significantly. Hospital mortality was 18% (2/11) in responders but remained high with 67% in 'non-responders' ! Interestingly only one single 12-h HVHF session was given.

Study concluded that a single session of HVHF may be use with benefit as salvage therapy in severe refractory hyperdynamic septic-shock patients.


Study to watch: IVOIRE (hIgh Volume in Intensive Care)



Reference:

High-volume hemofiltration as salvage therapy in severe hyperdynamic septic shock - Intensive Care Medicine - Volume 32, Number 5 / May, 2006

Thursday October 19, 2006


Q; How many percentage of PA catheter failed to obtain Wedge pressure (PAOP) ?

A; 25% 1
(so don't get dishearted and use PADP as a guide)


Related Previous Pearl:
Pulmonary Artery Diastolic-Pulmonary Wedge Pressure Gradient


Reference:
The ICU Book -Paul Marino - 3rd edition - Page 168

Wednesday October 18, 2006
Take home message about ICU scores

Mutiple scores have been developed to predict severity, prognosis, and outcome of diseases in ICU. (See all scores here from icumedicus site). All of these scores have their own flaws and none of them are perfect, like lactic acid level, a significant serial marker in ICU is not part of even APACHE IV score (Glucose level is now included). It takes a lot of effort and trained staff to implement these scoring systems. So what's the significance of using these various scores?

These scores serve the purposes of assessing therapies, quality control and assurance, and of an economic evaluation of intensive care as a whole. Like using these scores, if your's ICU lenght of stay or mortality rate is more than the predicted - it requires your attention in assessing therapies and quality assurance. Although these scores (like MPM) have been said to predict mortality in individual patients but in real life, note (and note again !) that these scores SHOULD NOT be applied in individual patients to predict mortality. This may create a psychological bias towards an individual patient.

Dr. Jack Zimmerman and coll. , looked into data of 116,209 patients for predicting ICU length of stay with The APACHE IV scores and come to the same conclusion that: "The APACHE IV model provides clinically useful ICU length of stay predictions for critically ill patient groups, but its accuracy and utility are limited for individual patients. APACHE IV benchmarks for ICU stay are useful for assessing the efficiency of unit throughout and support examination of structural, managerial, and patient factors that affect ICU stay".



Reference: click to get abstract

A randomized, controlled trial of the role of weaning predictors in clinical decision making -Critical Care Medicine. 34(10):2530-2535, October 2006.

Tuesday October 17, 2006


Q; So what should be the target vancomycin trough (or random) level ?

A: This month a retrospective study of 102 patients with MRSA has been published into 'chest' looking into benefit of higher vancomycin trough or random level (more than 15 µg/mL). The stratification of the vancomycin trough levels yielded no relationship with hospital mortality. Study found no evidence that higher vanco trough levels correlated with hospital outcome.

'Vanco level' between 5 to 15 µg/mL seems to be a reasonable target range.


Reference: click to get abstract

Predictors of Mortality for Methicillin-Resistant Staphylococcus aureus Health-Care–Associated Pneumonia - Specific Evaluation of Vancomycin Pharmacokinetic Indices - Chest. 2006;130:947-955.

Monday October 16, 2006

Scenario: You have a patient in unit whose blood sugar is hard to control despite aggressive insulin therapy. You wrote an order to prepare all drips and medications in either 0.9 or 0.45 NS (Normal Saline), as far as compatible. Next day, you noticed that pharmacy continue to prepare NOREPINEPHRINE (LEVOPHED) drip in mix with D5W. What do you think?

Answer: NOREPINEPHRINE (LEVOPHED) is less stable in normal saline (loose its potency from oxidation). Dextrose containg solution is preferred as the dextrose protects against oxidation of the norepinephrine and keep it active and stable.

Sunday October 15, 2006
Burnout among intensivists !!

We tried to explore literature to find studies related to burnout rate among intensivists. Interestingly, we found only 2 scientific studies each related to adult and pediatric intensivists. Both studies are available in references. These studies were done about 10 years ago and we assume that burnout rate is even higher today in view of more demand, recognition and acceptance of intensivist led model.


Adult Study:

248 physicians responded to tool of Maslach Burnout Inventory survey. MBI survey looks into 3 aspects of burnout

• Emotional exhaustion
• Depersonalization
• Personal accomplishment

A third of respondents scored in the high range of the emotional exhaustion, 20.4% of respondents scored in the high range of depersonalization score, and 59% scoring in the low range of personal achievement scores.

Pediatric study:

In this study, the Burnout Scale of Pines and Aronson was used and 389 pediatric intensivists responded. 11 years ago, 50% of pediatric intensivists were at risk of burned out. Interestingly, Overall, there was no association between having fellows; having protected time for research and publications; frequency of being called at home; frequency of returning to the hospital when called at home; or call schedule. (Routine exercise was associated with lower Burnout Scores).

In newly released US Department of Health and Human Services

Report to Congress: The Critical Care Workforce: A Study of the Supply and Demand for Critical Care Physicians - it has been predicted that by 2020, the demand for intensivists would likely increase by 129 percent above the current supply. The 2 major reasons for shortage would be the aging population and the increased utilization of intensivists(including burnout). Is it time for another survey from SCCM or ACCP ?

Related previous pearls:
Intensivists' compensation
Optimum patients' load for intensivist

References: click to get abstract/article

1. Burnout in the internist--intensivist. - Intensive Care Med.1996 Jul;22(7):625-30.
2. Physician burnout in pediatric critical care medicine. - Crit Care Med. 1995 Aug;23(8):1425-9

Friday October 13, 2006
Betdadine or Chlorhexidin ?

It is so true that scientific knowledge takes on average 17 years to travel from bench to bedside. Most of us grew up using Betadine (povidone-iodine) for bedside procedures but Dennis Maki published a study about 15 years ago in Lancet 1 randomizing solutions for skin preparation for 668 catheters, comparing 2% chlorhexidine, 10% povidone-iodine (betadine), and 70% alcohol. Chlorhexidine was associated with the lowest incidence of catheter-related-blood-stream-infections (CRBSI) with 2.3 per 100 catheters followed by Alcohol with 7.1 and povidone-iodine with 9.3 infections per 100 catheters. Another meta-analysis of 8 studies involving about 4000 catheters published in 2002 confirmed the above results 2.

Centers for Disease Control (CDC) as well as IHI (Institutefor Healthcare Improvement) now recommends to use 2% chlorhexidine instead of povidone-iodine(Betadine).


Related previous pearl:
Suture at central venous catheter site - a risk?


References:

1. Prospective randomised trial of povidone-iodine, alcohol, and chlorhexidine for prevention of infection associated with central venous and arterial catheters. - Lancet 1991;338:339-43. Maki DG, Ringer M, Alvarado CJ.

2. Chlorhexidine compared with povidone-iodine solution for vascular catheter-site care: a meta-analysis. (pdf) - Ann Intern Med 2002;136:792-801.

Thursday October 12, 2006
Why that PICC is purple ?
Power PICC


The use of multidetector CT scanners requires rapid injection of radiographic contrast media. Injecting contrast via regular PICC may cause rupture of catheter (rupture is recently reported with central venous catheter also 2) as well as it compromise clarity of images as target organ receives a bolus of the contrast media in a less concentrated dose. Power PICC is a new version of PICC line, identified by purple color and especially designed to inject radiological contrast media.

The maximum flow rate that can be used for power injection of contrast media through a PowerPICC is 5ml/sec but upto 2ml/sec is said to be satisfactory for imaging purposes 1. The maximum pressure the power injector should be set at 300 psi.

Again, you can recognize the PICC as a power injectable PICC, by its purple color port. The picture below is from www.bardaccess.com (makers of PICC lines). You can have more information from website also.

Bonus Pearl: Remember, central lines (TLC or PICC lines) are technically not ideal for IVF boluses due to longer length and smaller radius. 2 Large bore (say 18 gauge) peripheral IVs or one large bore central IV (cordis / introducer use for swan placement) are real placements for aggressive resuscitation (due to bigger radius and shorter length). [As per Hagen-Poiseuille equation just 2 fold increase in radius increase flow by 16 fold but 2 fold increase in length decrease flow by 50%].



Reference: click to get article

1. Power Injection of Contrast Media via Peripherally Inserted Central Catheters for CT - Journal of Vascular and Interventional Radiology 15:809-814 (2004)
2. Central line pump infusion and large volume mediastinal contrast extravasation in CT - British Journal of Radiology (2006) 79, e75-e77

Wednesday October 11, 2006


Q; 42 yr old male admitted with Guillain-Barré Syndrome and intubated due to rapidly falling vital capacity. Pt otherwise remain fairly stable and sedated with average dose of 5 mg/kg/hr Propofol. Unfortunately, patient failed 5 days of Plasma exchange therapy. On day 6, pt develop exacerbation of his baseline asthma and was started on IV solumedrol but steroids were discontinued next day on neurology’s recommendation as it may prolong recovery from GBS. All labs and clinical exam otherwise remain stable including mental status which was assessed briefly each morning while off sedation. DVT and GI prophylaxis on place. Enteral feeding started on day 2. Bedside percutaneous trach and PEG has been planned.

While on ICU shift on night of day 7, you noticed some downward trend on BP but as labs and exam so far remain rock stable, you attributed it to sedation. While browsing 5 AM labs you noticed PH of 7.25 and bicarb of 14. Chem-7 showed Cr of 2.1 (baseline 1.1) and K of 5.7. As you get more attentive to patient, you noticed frequent episodes of bradycardia on monitor. Tracking back monitor in last few hours showed multiple alarms for bradycardia but went unnoticed as this was the most stable patient in unit. Also pulse ox now trending in lower 90s. You ordered lactate level, cardiac enzymes, EKG, CXR, broad spectrum antibiotics, panculture, adjust ventilator and gave IVF bolus. Lactate level is back with 7.2 and indeed pt. has NSTE MI with Troponin-I of 7.1. You discuss case with primary service and now cardiology, nephrology and ID services are on case. Pt continue to deteriorate and died 48 hours later despite combined endeavors of all services to salvage his hemodynamic collapse.

Your diagnosis: (Choose one)

A. Acute MI from plasma exchange therapy.
B. Acute septic shock due to use of steroid.
C. Side effect of propofol.
D. Acute renal failure from hypotension.
E. Ventilator associated pneumonia.



Ans is (C): Propofol infusion syndrome

As propofol has gained enormous popularity in ICUs, it is extremely important to be aware of "Propofol infusion syndrome" when drip is continued for more than 48 hours with dose above 5mg/kg/hr. Syndrome consist of myocardial failure, metabolic acidosis, renal failure, lipemia, rhabdomyolysis, and hyperkalemia. Clues to "Propofol infusion sundrome" are unexplained lactate level, bradycardia and increasing need for pressors. It’s a clinical diagnosis.

Due to poorly understood reason, syndrome is associated with acute neurological illnesses or acute inflammatory diseases and receiving steroids in addition to propofol. Some critics blame high lipid content of infusion for syndrome.

Discussing choices:

A is wrong as acute MI is associated with IVIG theraphy for GBS and unlikely with plasma exchange. Also, this patient finished his therapy 2 days ago.

B is wrong as there is no clear evidence of sepsis and short term use of steroid has less likely reason for acute sepsis. But please note that it is very important to practice aseptic technique while handling propofol.

D is possible but it is unlikely that extreme hypotension will go unnoticed in ICU.

E - VAP is not associated with this clinical picture


Reference:

Ann Pharmacother. 2002 Sep;36(9):1453-6, The Lancet 2001;357:117-118, Intensive Care Med. 2003 Sep;29(9):1417-25.

Bonus Pearl: Propofol infusion is noticed to turn colour of urine green. It is a benign potential side effect of Propofol. Recognition of this side effect is important as it averts unnecessary further workup and limits medical expenditures.

Tuesday October 10, 2006
Propylene glycol and Ativan drip

Propylene glycol, also known as 1,2-propanediol, is a tasteless, odorless, and colorless liquid that is use for many drugs with poor aqueous solubility including lorazepoam, diazepam, esmolol, nitroglycerin, pentobarbital, phenytoin, bactrim and others. Usually it is safe but important to know that it is metabolized into lactic acid and pyruvate.

Being an intensivist it is imperative to understand the dangers of propylene glycol particularly with Lorazepam drip - particularly if it is continued beyond 48 hours and dose more than 10 mg/hr. Each 2 mg of lorazepam (one ml) on average contains 0.8 ml of propylene glycol. Any unexplained high anion gap metabolic acidosis with elevated osmol gap, should prompt the diagnosis of propylene gylcol toxicity.

Propylene glycol toxicity secondary to high-dose lorazepam infusion should be kept in mind with compromised renal function but may happen with normal kidney. Although propylene glycol toxicity often resolves after discontinuation of Ativan but if acidosis continues, hemodialysis said to lowers propylene glycol serum concentrations.

Monday October 09, 2006
Gastrointestinal Complications in Patients Undergoing Heart Operation

An important article published last year in Annals of Surgery 1 and should be read by intensivists working particularly in cardiothoracic units (CT-CV-ICU).

8709 Consecutive Cardiac Surgical Patients were analyzed for gastrointestinal complications. Though GI complications are rare (n = 46 - 0.53%) but need great vigilance of intensivist as these are life saving if identify early. Intensivist should not get deceived if surgery is off-pump 2 or minimally invasive (MIDCAB) 3.


Preoperative predictors of complication were

• Prior cerebrovascular accident (CVA),
• Chronic obstructive pulmonary disease (COPD),
• Heparin-induced thrombocytopenia (Type II),
• Atrial fibrillation,
• Prior myocardial infarction,
• Renal insufficiency,
• Hypertension, and
• need for intra-aortic balloon counter-pulsation (IABP).
  

The most frequent serious GI complication were

• Mesenteric ischemia (n = 31/46 or 67% of patients). 22 Twenty-two were explored and 14 died within 2 days of heart operation. Of the 9 patients with mesenteric ischemia who were not explored, 7 died within 3 days of heart operation.
• Diverticulitis (5/46),
• Pancreatitis (4/46),
• Peptic ulcer disease (4/46), and
• Cholecystitis (2/46).
  

Predictors of death from GI complication included

• New York Heart Association class III and IV heart failure,
• Smoking,
• Chronic obstructive pulmonary disease,
• History of syncope,
• AST more than 600U/L,
• Direct bilirubin more than 2.4mg/dL,
• PH less than 7.30, and
• The need for more than 2 pressors.
  
  Again! The biggest guard is high suspicion and constant vigilance.
  

References: click to get abstract or article

Gastrointestinal Complications in Patients Undergoing Heart Operation - Ann Surg. 2005 June; 241(6): 895–904.

Off-pump coronary artery bypass surgery does not reduce gastrointestinal complications. Eur J Cardiothorac Surg. 2003;23:170 --174

Acute Cholecystitis after Minimally Invasive Coronary Artery Bypass Grafting: A Report 2 Cases - The Heart Surgery Forum, Volume 9, Number 5 / October 2006

Sunday October 08, 2006
Topics you can't afford to miss for Critical Care Board exams - Part 3

Since last 2 weeks we are posting important topics to prepare for our fellows to prepare for Internal Medicine's Critical Care Board exam. Click for Part 1 and Part 2. Here are few more topics.

1. Indication of digibind in Dig toxicity
2. Management of pulmonary artery rupture (one lung ventilation)
3. Atrial fibrillation - Management in stable as well as hemodynamic shock
4. Amiodarone induced 'acute' lung toxicity
5. Identify pneumothorax in CXR
6. Identify central line in arterial system - CXR
7. CT scan picture in late stage ARDS
8. Calculation / formula of required calorie in ICU patient
9. C-diff colitis - identification
10. Identification / risk of DVT and PE in ICU patients
11. Diagnosis of TTP
12. Hepato-toxicity of Quinolones
13. Adjustment of Lovenox in renal failure
14. Hypophosphatemia in TPN
15. Tretment of organophophate poisioning
16. Management of acalculous cholycystitis after CABG.
17. Not to get deceive by mildly elevated BNP.
18. Antibiotic choice in neutropenic fever.
19. Need of Iron in Erythropoetin treatment.
20. Diagnosis of Abdominal compartment syndrome

Saturday October 07, 2006
French And Gauge


For Diameters of needles, catheters, tubes and wires there are 2 essential systems and it is important to understand the difference between two.

Gauge

Intensivists perform multiple procedures and use different wires while utilizing Seldinger’s technique or needles and IV catheters.

A traditional unit measuring the diameter (or the cross-sectional area) is Gauge. Various wire gauge scales have been used in the U.S. and Britain. The Stubs Iron Wire Gauge system (also known as the Birmingham Wire Gauge) is used in medicine to measure the diameter of hypodermic needles, intravenous catheters, and suture wires. It was originally developed in early 19th-century in England for use in wire manufacture, and it began appearing in a medical setting in the early 20th century. the Gauge system is not truly linear.

Needles / IV catheters: The needle gauge is inversely proportional to its diameter, so the larger the gauge number, narrower the diameter. Click here to see Needle Gauge Chart.

Wires: In traditional scales (U.S. STANDARD WIRE GAUGE), larger gauge numbers represent thinner wires. (For very thick wires, repeated zeros are used instead of negative numbers, so gauges 00, 000, and 0000 represent -1, -2, and -3, respectively.) For example, 0000 gauge represents a wire having a diameter of 0.46 inch and 36 gauge represents a diameter of 0.005 inch. Click here to see the table for U.S. STANDARD WIRE GAUGE.

French Sizing

Joseph-Frederic-Benoit Charriere was a 19th century maker of surgical instruments. Charriere made significant advances in ether administration, urologic, and other surgical instruments. He has credit of inventing the modern syringe. But his most significant contribution is to develop a uniform , standard gauge specifically designed for use in medical equipment such as catheters, drains and probes. Remember ! British system is not linear and confusing as Gauge # gets bigger, the diameter get smaller. Unlike the British gauge system Charriere's system (or French Gauge) has uniform increments between gauge sizes ( 1 French = 1/3 of a millimeter) and is easily calculated, linear and predictable like:

1 French = 1/3 of a millimeter , so
5 French = 1/3 x 5 = 1.66 millimeter


French Gauge sytem is mostly use for drains and tubes.

Friday October 06, 2006


Q: Why Etomidate may not be a good choice in neurological and neuro-surgical patients ?


A: It may decrease the seizure threshold.

Etomidate has fall out of favor in medical ICUs for intubation due to its transient effect of causing adrenal insufficiency, which makes it undesirable in septic patients. But another less known side effect is its ability to decrease the threshold for seizure.

Despite its effect on above 2 groups of patients, it is still a very valuable drug to use during intubation (atleast in other patients) due to its quality of having minimal effect on hemodynamic changes, faster effect (15 sec) and quick recovery (3-7 mins). Adrenocortical suppression after single dose is transient which last for 12-36 hours.


See nice review article : Should We Use Etomidate as an Induction Agent for Endotracheal Intubation in Patients WithSeptic Shock? - A Critical Appraisal from Dr. William L. Jackson, Critical Care Medicine Service, Department of Surgery, Walter Reed Army Medical Center, Washington, DC. (Chest. 2005;127:1031-1038.)

Thursday October 05, 2006
Electrical Impedance Tomography


Editors' note: We try to keep our visitors to be posted with new developing technologies applicable in ICU. The following technology is very interesting, portable at bedside and basically an another enhanced way of looking at structural as well as functional anatomy of desired organ - along with CT, MRI, EEG, echocardiogram, EEG etc


Electrical Impedance Tomography (EIT), is a medical imaging technique in which an image of the conductivity or permitivity of part of the body is inferred from surface electrical measurements. Although investigations with CT have taught us that ALI and ARDS are heterogeneous diseases and provide important information about alveolar collapse and reversal of atelactasis, it cannot be applied roultinly in ICU with ALI / ARDS patients.

EIT can produce images by placing electrodes around the anatomy of interest and studying the preferential paths of current flow. Computer reconstruction techniques are employed to generate images, which although of poor resolution, can give functional information in real time. EIT measures the distribution of impedance in a cross-section of the body. This is possible because the electrical resistivities of different body tissues varies widely from 0.65 ohm m for cerebrospinal fluid to 150 ohm m for bone.

Before data can be recorded a series of electrodes are attached to a subject in a transverse plane. These are linked to a data acquisition unit, which outputs data to a PC. By applying a series of small currents to the body a set of potential difference measurements can be made from non-current carrying pairs of electrodes. Since electric currents applied to the body take the paths of least impedance, where the currents flow depends on the subject's conductivity distribution. For example, the heart is full of blood. Blood conducts electricity well, so the heart has a low impedance. The lungs are filled with air. Air does not conduct electricity well, so the lungs have relatively high impedance. Therefore images can be reconstructed from the data using a variety a methods.

Proposed applications include monitoring of lung function, detection of cancer in the skin and breast and location of epileptic foci.

All applications are currently considered experimental.

Wednesday October 04, 2006


Q; You have admitted a patient with thyroid storm. You wrote all orders including IVF, tylenol (aspirin is relatively contraindicated for control of pyrexia in thyroid storm), propranolol, hydrocortisone, propyl thiouracil (PTU)and order for oral potassium iodide one hour after administration of PTU (Yes ! you have to wait one hour to give iodide after PTU or Methimazole) . You received call from pharmacy that patient has documented allergy to iodine in previous medical record. What's your next option instead of iodine ?


A; In patients allergic to iodine, you may use lithium carbonate to reduce secretion of pre-formed thyroid hormone. Start dose with 300 mg PO every 6 hours and follow level closely to keep at 1 meq/L.

Tuesday October 03, 2006
Correction of hypokalemia in hypothermia

Hypothermia commonly causes hypokalemia but should be treated very cautiously and gently. As patient has been re-warmed, potassium exits cells and may cause deadly hyperkalemia. 1, 2 This is not a pseudo-hypokalemia but a phenomenon of electrolyte movement across cell membrane induced by whole body temperature change. There should be a written protocol for gentle correction and followup of potassium during hypothermia and hyperthermia phase.


Bonus Pearl: Pseudo-hypokalemia

Pseudo-hypokalemia is usually seen with very high WBC count, when the drawn sample is allowed to sit at room temperature for longer period of time. It happens due to uptake of plasma potassium by high leukocytes in the sample. If Pseudo-hypokalemia is suspected, real potassium level can be measured by sending specimen quickly (preferably taking manually to lab as soon as drawn) and requesting to measure potassium level in separated plasma or serum.



Related previous Pearl: The TransTubular Potassium Gradient - TTKG




References: click to get articles/abstracts

1. Hypothermia-induced hypokalemia Mil Med.1998 Oct;163(10):719-21.

2. Serum potassium levels during prolonged hypothermia, Intensive Care Medicine Volume 9, Number 5 / September, 1983, 275-277

Monday October 02, 2006
DIABETIC LUNG

Pulmonary impairment in diabetes mellitus is under-recognized. The alveolar-capillary network receives the entire cardiac output and constitutes the largest microvascular organ in the body, making it highly susceptible to systemic microangiopathy. Owing to its large reserves, symptoms and disability develop later in the lung than in smaller microvasculature such as the kidney or retina despite a comparable severity of anatomic involvement.

It is not a new concept and numbers of classic studies are available. We just choose to ignore it !


* Investigators from the Copenhagen City Heart Study enrolled nearly 12,000 subjects ages 20 and older. Among them were 284 with clinician-diagnosed diabetes and 177 with abnormal glucose tolerance. On average, patients with diabetes had lower lung function values and a more rapid rate of decline than those without diabetes. At the five-year follow up lung function loss among diabetes patients exceeded that of the non-diabetes cohort by 29 ml (FVC) and 25 ml (FEV1) per year, a rate of decline comparable to that of smokers.


(Lange P, Groth S, Montensen J, et al. Diabetes mellitus and ventilatory capacity: a five year follow-up study, Eur Respir J. 1990;3:288-292)



* The Fremantle Diabetes Study from Australia plotted lung function values from 125 non-smokers with type II diabetes and no pre-existing lung disease over a seven-year period. During this time, the rate of lung function decline was about twice that expected (mean decrease, 68 ml/year for FVC and 71 ml/year for FEV1)

(Davis WA, Knuiman M, Kendall P, et al. Glycemic exposure is associated with reduced pulmonary function in type 2 diabetes: the Fremantle Study. Diabetes Care. 2004;27:752-757)


Other recommended readings: click to get articles

1. Lung Function and Glucose Metabolism: An Analysis of Data from the Third National Health and Nutrition Examination Survey - Am. J. Epidemiol. 2005;161:546-556.

2. Lung Dysfunction in Diabetes Goldman, Diabetes Care 2003;26:1915-1918.

Sunday October 01, 2006
Topics you can't afford to miss for Critical Care Board exams - Part 2


Last week we posted few important topics (click here to see) for our fellows for upcoming Internal Medicine's Critical Care board exam (November 8, 2006) . Here are few more topics you can't afford to miss for Critical Care Board exams.

1. Management of acute cirrhotic / variceal GI bleed
2. End of life issues / ethic questions - list of power of attorneys in order
3. Antibiotic choices in necrotising fascitis.
4. Hepato-renal syndrome
5. Vancomycin dosing in CVVHD
6. Baterial menigitis CSF findings and treatment
7. VAP - diagnosis and treatment
8. Thrombolytics and surgical indications in PE
9. EKG findings in Acute MI and pericarditis
10. EKG findings in hyperkalemia
11. Clinical scenario and acute management of venous air embolism
12. Treatments of hypothermia (all time board's favourite)
13. Hypokalemia in hypothermia
14. Asystole in hypothermia - approach to treatment
15. Indication of dialysis in lithium overdose
16. Cholesterol emboli - diagnosis
17. Contrast induced nephropathy - preventions
18. Arterial line - underdamp and overdamp picture
19. Green urine after propofol drip
20. QT interval prolongation with haldol.