TIP: Suspect when abdominal pain presents 10-14 after chemotherapy (when PMNs are lowest).
Acute Liver Failure (ALF)
Although oral metronidazole is indicated for mild to moderate Clostridium difficile associated diarrhea, oral vancomycin should be considered first-line therapy in critically-ill patients with moderate to severe disease. Vancomycin dosing should begin at 125mg PO q6 and increased to 250mg q6 if poor enteral absorption exists. Consider adding metronidazole IV if either reduced enteral absorption or severe disease exists.
Recently, fidaxomicin has been shown to be non-inferior to oral vancomycin in the treatment of mild to moderate C. difficile. While promising, the study population was not critically-ill and extrapolation should be avoided.
Gastrointestinal Changes of Obesity that Complicate Critical Illness
A mortality benefit from combination antimicrobial therapy has not been clearly demonstrated in sepsis. However, when only the most severely-ill patients (i.e., septic shock) are considered in subgroup analysis, there appears to be a mortality benefit to using two antimicrobials against a suspected organism.
Combination antimicrobial therapy may reduce mortality through three mechanisms.
Always obtain appropriate cultures before initiating therapy. Although identification and susceptibility of the organism may take some time, eventually narrowing antimicrobial therapy to monotherapy in the ICU is still recommended.
Combination Antimicrobial Therapy for Gram (+) Bacteremia
Vancomycin is often started empirically for gram-positive and MRSA coverage. Although effective and generally well-tolerated, emerging resistance and side-effect profiles limit its use in some patients. Two alternatives are Linezolid and Daptomycin.
Linezolid
Daptomycin
Emergency Medicine physicians are gaining experience with non-invasive ventilation (i.e., Bi-level ventilation and continuous positive-pressure ventilation) in managing respiratory distress and failure. Although NIV is commonly used across a variety of pathologies, the best data exists for use with COPD exacerbation and cardiogenic pulmonary edema (CHF, not an acute MI)
Although other indications for NIV have been studied, the data is less robust (eg., smaller study size, weak control groups, etc.). If there are no contraindications, however, many experts still support a trial of NIV in the following populations:
Failure to clinically improve during a NIV trial should prompt invasive mechanical ventilation.
Aspiration Pneumonitis and Pneumonia
Many changes in pulmonary physiology occur during pregnancy. These changes are generally well tolerated but can become problematic when pathologic states arise.
Here are a few examples of the normal changes and potential consequences:
Progesterone increases tidal volume and respiratory rate.
“Normally" a mild respiratory alkalosis pH 7.4-7.47, PaCO2 28-32, and bicarbonate 17-22 (renal compensation).
Low metabolic reserve with systemic illness.
Weight gain, anasarca, and breast size reduces chest wall elasticity.
Potential for restrictive physiology and reduced lung volumes.
Can be challenging to to mechanically ventilate due to decreased compliance and intra-thoracic pressure
Mechanical displacement of abdominal and thoracic contents by growing uterus.
Reduced lung volumes leading to reduced oxygen reserve and decreased apnea time.
Aim higher if placing chest tube (avoid abdominal contents)
Uterine pressure on stomach can increase aspiration risk and pulmonary injury.
The Severely Hypoxemic ED Patient
Hemodynamic Monitoring in the Ventilated Patient
Acute LV Dysfunction in the Critically Ill
The optimal hemoglobin concentration during critical illness is unknown. Although a liberal transfusion strategy (Hb 10-12 g/dL) was once believed to be beneficial for hemodynamics, evidence suggests targeting a conservative strategy (Hb 7-9 g/dL) does not increase mortality, while the unnecessary transfusion of blood products can cause harm (transfusion associated lung injury, infection, etc.) in the non-hemorrhaging patient.
Valproic Acid in Status Epilepticus
Brain death is the permanent absence of cerebral and brainstem functions (coma, absent pupillary reflexes, no spontaneous respiration, etc.). Legally, brain death is equivalent to cardiopulmonary death.
If brain death is suspected, confirmation is necessary. The apnea test is most commonly used, evaluating for spontaneous breaths when disconnected from the ventilator. If apnea testing is not possible (e.g., ambiguous clinical exam or cardiopulmonary instability) ancillary testing is needed:
Dexmedetomidine for Sedation in Acute Neurologic Disease
Posterior reversible encephalopathy syndrome (PRES) is a syndrome of visual loss, headache, altered mental status, and seizures, typically with severe hypertension. PRES usually occurs with hypertensive encephalopathy or ecclampsia, although cyclosporin and tacrolimus use have been implicated.
PRES is due to a combination of endothelial damage, impaired auto-regulation and increased cerebral perfusion pressure. Classic CT and MRI findings are parietal-occipital, cerebellar, or brainstem cortical and subcortical edema.
Early recognition and symptomatic treatment is key; IV anti-hypertensives (hypertensive encephalopathy), anti-epileptics (seizures), IV magnesium and emergent delivery (ecclampsia), and discontinuing offending medications (cyclosporin and tacrolimus).
With treatment, partial to complete recovery is normal, although residual neurological and visual deficits may persist.
Vancomycin Dosing in the Critically Ill Obese Patient
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