Partial pressure of carbon dioxide/pH interaction and its association with mortality among patients mechanically ventilated in the emergency department.

OBJECTIVES: There is currently conflicting data as to the effects of hypercapnia on clinical outcomes among mechanically ventilated patients in the emergency department (ED). These conflicting results may be explained by the degree of acidosis. We sought to test the hypothesis that hypercapnia is associated with increased in-hospital mortality and decreased ventilator-free days at lower pH, but associated with decreased in-hospital mortality and increased ventilator-free days at higher pH, among patients requiring mechanical ventilation in the emergency department (ED). METHODS: Secondary analysis of patient level data from prior clinical trials and cohort studies that enrolled adult patients who required mechanical ventilation in the ED. Patients who had a documented blood gas while on mechanical ventilation in the ED were included in these analyses. The primary outcome was in-hospital mortality, and secondary outcome was ventilator-free days. Mixed-effects logistic, linear, and survival-time regression models were used to test if pH modified the association between partial pressure of carbon dioxide (pCO2) and outcome measures. RESULTS: Of the 2348 subjects included, the median [interquartile range (IQR)] pCO2 was 43 (35-54) and pH was 7.31 (7.22-7.39). Overall, in-hospital mortality was 27%. We found pH modified the association between pCO2 and outcomes, with higher pCO2 associated with increased probability of in-hospital mortality when pH is below 7.00, and decreased probability of in-hospital mortality when pH is above 7.10. These results remained consistent across multiple sensitivity and subgroup analyses. A similar relationship was found with ventilator-free days. CONCLUSIONS: Higher pCO2 is associated with decreased mortality and greater ventilator-free days when pH is >7.10; however, it is associated with increased mortality and fewer ventilator-free days when the pH is below 7.00. Targeting pCO2 based on pH in the ED may be a potential intervention target for future clinical trials to improve clinical outcomes.

Spontaneous Cerebrospinal Fluid Leak in a Patient with Asymptomatic Idiopathic Intracranial Hypertension.

BACKGROUND: Spontaneous cerebrospinal fluid (CSF) leaks occur when there is a tear in the dura mater. Spontaneous CSF leaks are rare, and often associated with conditions like intracranial hypertension, connective tissue disorders, or congenital defects in the dura mater. CASE REPORT: The patient was a 66-year-old woman who presented to the Emergency Department with clear, positional nasal discharge from her left nostril for 1 week. She had a history of chronic headaches, which seemed to have been relieved around the time of onset of her rhinorrhea. Diagnostic imaging, including computed tomography and magnetic resonance imaging scans, confirmed the presence of a CSF leak and a left temporal meningoencephalocele. The patient subsequently underwent surgical repair of the leak and ventriculoperitoneal shunt placement, and was discharged home in stable condition. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Early detection of CSF leaks require a thorough history and physical examination, and is crucial in preventing potentially life-threatening complications such as meningitis and intracranial abscesses.