Burn Patients and Antibiotic Dosing
Previous pearls have described the increasing evidence against colloid (e.g., hydroxyethyl starch) use during resuscitation. Now it appears that the crystalloid 0.9% normal saline (NS) may be under fire.
The use of large volumes of NS has been associated with hyperchloremic metabolic acidosis and harm in animal studies. The risk of harm in humans, however, has been less clear.
Bellomo et al. conducted a prospective observational study in which patients being resuscitated in the control group received NS at the clinicians' discretion; i.e., chloride-liberal strategy. The use of NS was restricted in the intervention group, where other less chloride containing fluids were used for resuscitation (e.g., Ringer's Lactate); i.e., a chloride-restrictive strategy.
The authors found that when compared to patients in the chloride-liberal group, the chloride-restrictive group had significantly less rise in baseline creatinine, less overall AKI, and a reduced need for renal replacement therapy.
Bottom line: Although this was only an observational study, the liberal use of normal saline during resuscitation may increase the risk of AKI and renal replacement therapy.
Serotonin Toxicity in the Critically Ill
Delirium in the Critically Ill
70 year-old male recently treated for community-acquired pneumonia presents with bloody diarrhea, fever, and severe abdominal pain. Abdominal Xray is shown below. Diagnosis?
Thrombotic Thrombocytopenic Purpura (TTP)
Intubated patients may occasionally meet certain criteria for extubation while in the Emergency Department. Extubation is not without its risk, however, as up to 30% of patients have respiratory distress secondary to laryngeal and upper airway edema, with some patients requiring re-intubation.
Prior to extubation, Intensivists use a brief “cuff-leak” test (deflation of the endotracheal balloon to assess the presence or absence of an air-leak around the tube) to indirectly screen for the presence of upper airway edema and ultimately the risk of re-intubation. The cuff-leak test is performed by deflating the endotracheal balloon followed by one or more of the following maneuvers:
Ochoa et al. performed a systematic review to determine the accuracy of the “cuff-leak” test to predict upper airway edema prior to extubation. The authors concluded that a positive cuff-leak test (i.e., absence of an air-leak) indicates an elevated risk of upper airway obstruction and re-intubation. A negative cuff-leak test (i.e., presence of an air-leak), however, does not reliably exclude the presence of upper airway edema or the need for subsequent re-intubation.
Bottom line: No test prior to extubation reliably predicts the absence of upper airway edema. Patients extubated in the Emergency Department require close observation with airway equipment located nearby.
The Lung Transplant Patient in Your ED
40 year-old male with severe uncontrolled hypertension presents with altered mental status (head CT below). The CXR is from the same patient. What's the connection?
Right Heart Failure in the Critically Ill
A Cochrane review of 37 studies concluded that Succinylcholine (SUC) is superior to Rocuronium (ROC) during rapid sequence intubation.
The authors claim that compared to ROC, SUC has a faster onset of action (45 vs. 60 seconds) and overall a shorter duration of action (10 vs. 60 minutes).
Dr. Reuben Strayer wrote a letter to the journal editors and stated that these findings should be interpreted carefully; he highlighted that most of the studies in the review used doses of ROC less than 0.9 mg/kg (most studies used 0.6mg/kg).
Dr. Strayer asserted that ROC’s onset of action is dose dependent; when using doses of 1.2 mg/kg, ROC’s onset is indistinguishable from that of SUC. He also stated another major benefit of ROC is the lack of adverse effects that SUC possesses (hyperkalemia and malignant hyperthermia).
What are your thoughts on this? Go to http://www.facebook.com/Criticalcarenow and take the poll (there are 5 choices). Results will be posted next week.
AKI and Fluid Balance
Femoral venous access is typically limited to the acute resuscitation of critically-ill patients. Several practice-guidelines recommend avoiding the femoral site, or removal once admitted to the ICU, because of the risk of catheter-related bloodstream infection (CRBI) and deep-vein thrombosis (DVT).
A recent systematic review and meta-analysis (including two randomized-control trials and eight cohort-studies) evaluated the risk of CRBI and DVT for catheters placed in either the internal jugular, subclavian, or femoral-venous sites. No difference in the rate of CRBI or DVT was found between the three sites, although the DVT data was less robust (i.e., contained heterogeneous data).
The authors hypothesized that improvements in sterility during central-line placement (e.g., full-barrier precautions), improved nursing care (e.g., central-line site care), and ultrasound guidance may have led to a reduction in femoral site complications.
Although a prospective randomized-control trial is necessary to confirm these results, this meta-analysis challenges the traditional teaching that femoral central-access should be avoided.
Lung Protective Ventilator Settings Still Underutilized
Crystalloids (i.e., 0.9% saline and lactated ringers) have been used during resuscitation for more than a century. Their invention, however, was more accidental than intentional.
Crystalloids were first used during the European Cholera epidemic of 1831. Hartog Hamburger later modified this solution in 1896 to the solution we know today as "normal" saline. Hamburger's solution was only intended for in vitro study of RBC lysis and was never intended for clinical use.
Around this time, Sydney Ringer was testing several fluids to use for physiologic studies. Ringer's lab assistant was erroneously substituting tap water for distilled water when preparing these solutions. Ringer later discovered that this tap water contained minerals making the solution "physiologic", isotonic, and safe for human use; Alexis Hartmann later added sodium lactate to create Ringer's Lactate.
Since the invention of crystalloids, many types of resuscitation fluids have been created and studied (i.e., albumins, gelatins, and starches); all have been shown to be more expensive, with no more benefit, and with possibly more harm when compared to crystalloids.
The "perfect" resuscitation fluid still alludes us today, but of all of the solutions marketed crystalloids are arguably the best...despite their accidental history.
Steroids and Septic Shock
Wernicke encephalopathy (WE) is a neurologic disorder secondary to prolonged thiamine deficiency; it is characterized by confusion, ataxia, and ocular abnormalities.
Traditional medical teaching advises against the administration of glucose (or glucose containing fluid) in thiamine deficient patients, without first giving thiamine, as this may precipitate WE.
This teaching is problematic, however, in hypoglycemic patients who require the immediate administration of glucose while simultaneously being suspected of thiamine deficiency (e.g., malnourished alcoholics). Delays in treating hypoglycemia may be more harmful (e.g., seizures, permanent neurologic deficits, etc.) than the risk of WE.
Schabelman et. al performed a literature search to unearth the origins of this teaching. Nineteen papers related to this topic were found consisting of case reports, animal studies, and expert opinion; there were no randomized trials, cohort studies, or case-control studies.
Bottom-line: The available evidence does not support withholding glucose treatment until thiamine can be administered and educators should consider abolishing this dogmatic teaching until better evidence is available.
Anaphylaxis
Septic patients with hemodynamic instability often require intravenous fluids as part of their resuscitation. Major debate has occurred whether the optimal resuscitation fluids are crystalloids (e.g., normal saline) or colloids (e.g., albumin).
In theory, colloids are more potent intravascular expanders than crystalloids because their oncotic pressure is higher and should increase intravascular volume similarly to larger amounts crystalloid (i.e., colloids require less volume during resuscitation).
Despite these theoretical benefits, the colloid hydroxyethyl starch (HES), has come under scrutiny after prior studies have linked its use with adverse outcomes.
A recent prospective randomized-control trial compared the use of HES to lactated acetate for resuscitating septic patients and found that HES significantly increased both the incidence of renal-replacement therapy and mortality at 90 days (both primary end-points in the study).
Bottom line: There is no convincing data that HES performs superiorly to crystalloid for resuscitation in sepsis and there is increased harm with its use. Furthermore, the increased cost of HES compared to crystalloids does not justify its routine use.
