Arterial to end-tidal carbon dioxide gap and its characterization in mechanically ventilated adults in the emergency department.

PURPOSE: To evaluate early measurement of the arterial to end-tidal carbon dioxide (PaCO2-PetCO2) gap, a surrogate for physiologic dead space, and its association with clinical outcomes in intubated adults in the emergency department (ED). MATERIALS AND METHODS: Observational cohort study of invasively mechanically ventilated adults in an academic medical center (years 2009 to 2016). The association of the PaCO2-PetCO2 gap was evaluated with respect to clinical outcomes; the primary outcome was in-hospital mortality. RESULTS: 519 patients were included. 325 (63%) patients had an elevated (>5 mmHg) PaCO2-PetCO2. Patients with an elevated PaCO2-PetCO2 were significantly older, had higher APACHE II scores, more frequently had chronic obstructive pulmonary disease (COPD), had lower arterial oxygen to fraction of inspired oxygen (P:F) ratios, and were more likely to be intubated for exacerbation of COPD or sepsis. There was no difference in mortality for patients with an elevated PaCO2-PetCO2 (25% vs 26%) in unadjusted analysis (p = 0.829) or adjusted analysis (aOR = 0.81 [95% CI: 0.53-1.26]), as compared to a non-elevated PaCO2-PetCO2. CONCLUSIONS: An elevated PaCO2-PetCO2 gap is common in the post-intubation period in the ED, but not significantly associated with clinical outcomes.

Symptomatic Cholelithiasis of a Remnant Gallbladder after Open Cholecystectomy.

BACKGROUND: Recurrent abdominal pain, particularly in the right upper quadrant (RUQ) in a patient with a history of cholecystectomy, known as postcholecystectomy syndrome, requires a broad differential diagnosis. Pathology of a retained gallbladder remnant is an exceedingly rare etiology of this pain. CASE REPORT: A 49-year-old woman who had previously undergone an open cholecystectomy presented to the emergency department with several hours of postprandial RUQ pain and emesis. Liver function tests and lipase were not significantly elevated. RUQ ultrasonography revealed a cystic structure containing a stone with mild prominence of the common bile duct at 7 mm, and magnetic resonance cholangiopancreatography confirmed the presence of a remnant gallbladder without common bile duct obstruction. Her pain subsided, she tolerated a diet, and was discharged with a referral for an elective cholecystectomy. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Abdominal pain is the most common chief complaint of patients presenting to the emergency department in the United States, and emergency physicians routinely encounter patients with postcholecystectomy syndrome. Emergency physicians should not exclude the possibility of remnant gallbladder pathology, such as symptomatic cholelithiasis or cholecystitis, in patients presenting with symptoms concerning for biliary colic, even if the patient has undergone previous cholecystectomy.

Comparison of Etomidate and Ketamine for Induction During Rapid Sequence Intubation of Adult Trauma Patients.

STUDY OBJECTIVE: Induction doses of etomidate during rapid sequence intubation cause transient adrenal dysfunction, but its clinical significance on trauma patients is uncertain. Ketamine has emerged as an alternative for rapid sequence intubation induction. Among adult trauma patients intubated in the emergency department, we compare clinical outcomes among those induced with etomidate and ketamine. METHODS: The study entailed a retrospective evaluation of a 4-year (January 2011 to December 2014) period spanning an institutional protocol switch from etomidate to ketamine as the standard induction agent for adult trauma patients undergoing rapid sequence intubation in the emergency department of an academic Level I trauma center. The primary outcome was hospital mortality evaluated with multivariable logistic regression, adjusted for age, vital signs, and injury severity and mechanism. Secondary outcomes included ICU-free days and ventilator-free days evaluated with multivariable ordered logistic regression using the same covariates. RESULTS: The analysis included 968 patients, including 526 with etomidate and 442 with ketamine. Hospital mortality was 20.4% among patients induced with ketamine compared with 17.3% among those induced with etomidate (adjusted odds ratio [OR] 1.41; 95% confidence interval [CI] 0.92 to 2.16). Patients induced with ketamine had ICU-free days (adjusted OR 0.80; 95% CI 0.63 to 1.00) and ventilator-free days (adjusted OR 0.96; 95% CI 0.76 to 1.20) similar to those of patients induced with etomidate. CONCLUSION: In this analysis spanning an institutional protocol switch from etomidate to ketamine as the standard rapid sequence intubation induction agent for adult trauma patients, patient-centered outcomes were similar for patients who received etomidate and ketamine.

Cell-free hemoglobin: a novel mediator of acute lung injury.

Patients with the acute respiratory distress syndrome (ARDS) have elevated levels of cell-free hemoglobin (CFH) in the air space, but the contribution of CFH to the pathogenesis of acute lung injury is unknown. In the present study, we demonstrate that levels of CFH in the air space correlate with measures of alveolar-capillary barrier dysfunction in humans with ARDS (r = 0.89, P < 0.001) and in mice with ventilator-induced acute lung injury (r = 0.89, P < 0.001). To investigate the specific contribution of CFH to ARDS, we studied the impact of purified CFH in the mouse lung and on cultured mouse lung epithelial (MLE-12) cells. Intratracheal delivery of CFH in mice causes acute lung injury with air space inflammation and alveolar-capillary barrier disruption. Similarly, in MLE-12 cells, CFH increases proinflammatory cytokine expression and increases paracellular permeability as measured by electrical cell-substrate impedance sensing. Next, to determine whether these effects are mediated by the iron-containing heme moiety of CFH, we treated mice with intratracheal hemin, the chloride salt of heme, and found that hemin was sufficient to increase alveolar permeability but failed to induce proinflammatory cytokine expression or epithelial cell injury. Together, these data identify CFH in the air space as a previously unrecognized driver of lung epithelial injury in human and experimental ARDS and suggest that CFH and hemin may contribute to ARDS through different mechanisms. Interventions targeting CFH and heme in the air space could provide a new therapeutic approach for ARDS.

Community-Acquired Pneumonia Visualized on CT Scans but Not Chest Radiographs: Pathogens, Severity, and Clinical Outcomes.

BACKGROUND: The clinical significance of pneumonia visualized on CT scan in the setting of a normal chest radiograph is uncertain. METHODS: In a multicenter prospective surveillance study of adults hospitalized with community-acquired pneumonia (CAP), we compared the presenting clinical features, pathogens present, and outcomes of patients with pneumonia visualized on a CT scan but not on a concurrent chest radiograph (CT-only pneumonia) and those with pneumonia visualized on a chest radiograph. All patients underwent chest radiography; the decision to obtain CT imaging was determined by the treating clinicians. Chest radiographs and CT images were interpreted by study-dedicated thoracic radiologists blinded to the clinical data. RESULTS: The study population included 2,251 adults with CAP; 2,185 patients (97%) had pneumonia visualized on chest radiography, whereas 66 patients (3%) had pneumonia visualized on CT scan but not on concurrent chest radiography. Overall, these patients with CT-only pneumonia had a clinical profile similar to those with pneumonia visualized on chest radiography, including comorbidities, vital signs, hospital length of stay, prevalence of viral (30% vs 26%) and bacterial (12% vs 14%) pathogens, ICU admission (23% vs 21%), use of mechanical ventilation (6% vs 5%), septic shock (5% vs 4%), and inhospital mortality (0 vs 2%). CONCLUSIONS: Adults hospitalized with CAP who had radiological evidence of pneumonia on CT scan but not on concurrent chest radiograph had pathogens, disease severity, and outcomes similar to patients who had signs of pneumonia on chest radiography. These findings support using the same management principles for patients with CT-only pneumonia and those with pneumonia seen on chest radiography.