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OBJECTIVES:. For patients with acute respiratory distress syndrome (ARDS) receiving venovenous extracorporeal membrane oxygenation (ECMO) who develop acute kidney injury (AKI) requiring kidney replacement therapy (KRT), the inability to renally compensate for respiratory acidosis could result in increased sweep gas flow to normalize arterial pH. Our objective was to examine the relationship of serum bicarbonate levels, arterial pH, sweep gas flow, and Paco2. DESIGN:. This is a retrospective cohort study. We compared patients who received KRT while undergoing venovenous ECMO to patients who did not. SETTING:. Vanderbilt University Medical Center, February 2019 to February 2022. PATIENTS:. We examined data from adult patients receiving venovenous ECMO for ARDS. INTERVENTIONS:. Values for serum bicarbonate, arterial pH, Paco2, and sweep gas flow were collected daily from time of cannulation until the earlier of decannulation, 30 days, or death. MEASUREMENTS AND MAIN RESULTS:. Of the 126 patients included, 53 (42.1%) received KRT and 73 (57.9%) did not. In patients who received KRT, mean serum bicarbonate levels remained between 22 and 28 mmol/L throughout the study period. Patients who did not receive KRT experienced an increase in mean serum bicarbonate levels over time up to 40 mmol/L (mean difference = –4.4 mmol/L [95% CI, –6.3 to –2.5 mmol/L]; p < 0.0001). Mean values for Paco2 (–5.2 [95% CI, –8.8 to –1.7]; p = 0.004) and pH (–0.03 [95% CI, –0.03 to –0.02]; p < 0.0001) were lower in patients who received KRT than in patients who did not, despite higher sweep gas flow rates in patients who received KRT than in patients who did not (mean difference = 1.5 [95% CI, 0.8–2.3]; p < 0.001). CONCLUSIONS:. ARDS patients on venovenous ECMO with preserved kidney function experience an increase in bicarbonate concentration over time, compared to patients with AKI on KRT. Whether this increase in bicarbonate concentration increases pH, decreases sweep gas flow requirements, and facilitate weaning from venovenous ECMO requires examination in future research.

OBJECTIVE:. Hypotension affects approximately 40% of critically ill patients undergoing emergency intubation and is associated with an increased risk of death. The objective of this study was to examine the association between prophylactic vasopressor administration and the incidence of peri-intubation hypotension and other clinical outcomes. DESIGN:. A secondary analysis of two multicenter randomized clinical trials. The clinical effect of prophylactic vasopressor administration was estimated using a one-to-one propensity-matched cohort of patients with and without prophylactic vasopressors. SETTING:. Seven emergency departments and 17 ICUs across the United States. PATIENTS:. One thousand seven hundred ninety-eight critically ill patients who underwent emergency intubation at the study sites between February 1, 2019, and May 24, 2021. INTERVENTIONS:. None. MEASUREMENTS AND MAIN RESULTS:. The primary outcome was peri-intubation hypotension defined as a systolic blood pressure less than 90 mm Hg occurring between induction and 2 minutes after tracheal intubation. A total of 187 patients (10%) received prophylactic vasopressors prior to intubation. Compared with patients who did not receive prophylactic vasopressors, those who did were older, had higher Acute Physiology and Chronic Health Evaluation II scores, were more likely to have a diagnosis of sepsis, had lower pre-induction systolic blood pressures, and were more likely to be on continuous vasopressor infusions prior to intubation. In our propensity-matched cohort, prophylactic vasopressor administration was not associated with reduced risk of peri-intubation hypotension (41% vs 32%; p = 0.08) or change in systolic blood pressure from baseline (–12 vs –11 mm Hg; p = 0.66). CONCLUSIONS:. The administration of prophylactic vasopressors was not associated with a lower incidence of peri-intubation hypotension in our propensity-matched analysis. To address potential residual confounding, randomized clinical trials should examine the effect of prophylactic vasopressor administration on peri-intubation outcomes.

OBJECTIVES:. Tracheal intubation (TI) is a common procedure in critical care, often performed with a Macintosh curved blade used for direct laryngoscopy (DL). Minimal evidence informs the choice between Macintosh blade sizes during TI. We hypothesized that Macintosh 4 blade would have higher first-attempt success than Macintosh 3 blade during DL. DESIGN:. Retrospective analysis using a propensity score and inverse probability weighting of data from six prior multicenter randomized trials. SETTING AND PARTICIPANTS:. Adult patients who underwent nonelective TI at participating emergency departments and ICUs. We compared the first-pass success of TI with DL in subjects intubated with a size 4 Macintosh blade on the first TI attempt to subjects with a size 3 Macintosh blade on the first TI attempt. MAIN RESULTS:. Among 979 subjects, 592 (60.5%) had TI using DL with a Macintosh blade, of whom 362 (37%) were intubated with a size 4 blade and 222 (22.7%) with a size 3 blade. We used inverse probability weighting with a propensity score for analyzing data. We found that patients intubated with a size 4 blade had a worse (higher) Cormack-Lehane grade of glottic view than patients intubated with a size 3 blade (adjusted odds ratio [aOR], 1.458; 95% CI, 1.064–2.003; p = 0.02). Patients intubated with a size 4 blade had a lower first pass success than those with a size 3 blade (71.1% vs 81.2%; aOR, 0.566; 95% CI, 0.372–0.850; p = 0.01). CONCLUSIONS AND RELEVANCE:. In critically ill adults undergoing TI using DL with a Macintosh blade, patients intubated using a size 4 blade on first attempt had a worse glottic view and a lower first pass success than patients intubated with a size 3 Macintosh blade. Further prospective studies are needed to examine the optimal approach to selecting laryngoscope blade size during TI of critically ill adults.

OBJECTIVES:. For critically ill adults, oxygen saturation is continuously monitored using pulse oximetry (Spo2) as a surrogate for arterial oxygen saturation (Sao2). Skin pigmentation may affect accuracy of Spo2 by introducing error from statistical bias, variance, or both. We evaluated relationships between race, Spo2, Sao2, and hypoxemia (Sao2 < 88%) or hyperoxemia (Pao2 > 150 mm Hg) among adults receiving mechanical ventilation in a medical ICU. DESIGN:. Single-center, observational study. SETTING:. Medical ICU at an academic medical center. PATIENTS:. Critically ill adults receiving mechanical ventilation from July 2018 to February 2021, excluding patients with COVID-19, with race documented as Black or White in the electronic medical record, who had a pair of Spo2 and Sao2 measurements collected within 10 minutes of each other. INTERVENTIONS:. None. MEASUREMENTS:. We included 1,024 patients with 5,557 paired measurements within 10 minutes, of which 3,885 (70%) were within 1 minute. Of all pairs, 769 (14%) were from Black patients and 4,788 (86%) were from White patients. In analyses using a mixed-effects model, we found that across the range of Spo2 values of 92–98%, the associated Sao2 value was approximately 1% point lower for Black patients compared with White patients. Among patients with a Spo2 value between 92% and 96%, Black patients were more likely to have both hypoxemia (3.5% vs 1.1%; p = 0.002) and hyperoxemia (4.7% vs 2.4%; p = 0.03), compared with White patients. CONCLUSIONS:. Among patients with a measured Spo2 of 92–96%, greater variation in Sao2 values at a given Spo2 resulted in a higher occurence rate of both hypoxemia and hyperoxemia for Black patients compared with White patients.