Comparison of the Effectiveness of Nasal Cannula Versus Face Mask With Reservoir Bag in Postoperative Patients Undergoing General Anesthesia: A Prospective Randomized Controlled Trial.

BACKGROUND: High-concentration oxygen delivery via a face mask (FM) with a reservoir bag is a common practice to prevent postoperative hypoxemia; however, it may also lead to atelectasis and other respiratory complications. Lower concentrations delivered via nasal cannula (NC) may be equally effective in preventing postoperative hypoxemia. The present study aimed to compare peripheral oxygen saturation (SpO_2) delivered via NC versus FM with a reservoir bag in patients who have undergone general anesthesia (GA). METHODS: Eighty-four patients scheduled for GA were randomized to receive either oxygen via NC (NC group, n = 42) or FM with a reservoir bag (FM group, n = 42) for 30 minutes after GA at a postanesthesia care unit (PACU). All patients were assessed based on SpO_2 value, adverse events, and patient satisfaction (measured using a 100-mm visual analog scale). RESULTS: The overall difference between groups in the change of SpO_2 over 30 minutes at the PACU was -0.004 (95% confidence interval, -0.015 to 0.008; P = 0.527). SpO_2 during the first five minutes was lower in NC group, but the difference was not statistically significant. No desaturation occurred in either group, and there was no observed difference between groups in terms of adverse events. Patient satisfaction scores were also similar (P = 0.612). CONCLUSIONS: Oxygen supplementation via NC and via FM with a reservoir bag were equally effective in preventing postoperative hypoxemia after GA.

Venovenous extracorporeal membrane oxygenation versus conventional mechanical ventilation to treat refractory hypoxemia in patients with acute respiratory distress syndrome: a retrospective cohort study.

OBJECTIVE: To compare the treatment outcome of venovenous extracorporeal membrane oxygenation (VV-ECMO) versus mechanical ventilation in hypoxemic patients with acute respiratory distress syndrome (ARDS) at a referral center that started offering VV-EMCO support in 2010. METHODS: This retrospective cohort study enrolled adults with severe ARDS (PaO2/FiO2 ratio of <100 with FiO2 of ≥90 or Murray score of ≥3) who were admitted to the intensive care unit of Siriraj Hospital (Bangkok, Thailand) from January 2010 to December 2018. All patients were treated using a low tidal volume (TV) and optimal positive end-expiratory pressure. The primary outcome was hospital mortality. RESULTS: Sixty-four patients (ECMO, n = 30; mechanical ventilation, n = 34) were recruited. There was no significant difference in the baseline PaO2/FiO2 ratio (67.2 ± 25.7 vs. 76.6 ± 16.0), FiO2 (97 ± 9 vs. 94 ± 8), or Murray score (3.4 ± 0.5 vs. 3.3 ± 0.5) between the ECMO and mechanical ventilation groups. The hospital mortality rate was also not significantly different between the two groups (ECMO, 20/30 [66.7%] vs. mechanical ventilation, 24/34 [70.6%]). Patients who underwent ECMO were ventilated with a significantly lower TV than patients who underwent mechanical ventilation (3.8 ± 1.8 vs. 6.6 ± 1.4 mL, respectively). CONCLUSION: Although VV-ECMO promoted lower-TV ventilation, it did not improve the in-hospital mortality rate. Trial registration: www.clinicaltrials.gov (NCT04031794).

Comparative study of minimal fresh gas flow used in Lack-Plus and Lack's circuit in spontaneously breathing anesthetized adults.

BACKGROUND: The Lack's circuit is a co-axial Mapleson A breathing system commonly used in spontaneously breathing anesthetized adults but still requires high fresh gas flow (FGF). The Lack-Plus circuit was invented with the advantage of lower FGF requirement. The authors compared the Lack-Plus and Lack's circuit for the minimal FGF requirement with no rebreathing in spontaneously breathing anesthetized adults. METHODS: This was a randomized crossover study. We enrolled 24 adult patients undergoing supine elective surgery, with a body mass index ≤30 kg/m2 and an American Society of Anesthesiologists physical status I-II. They were randomly allocated to group 1 (LP-L) starting with Lack-Plus then switching to Lack's circuit or group 2 (L-LP) (with the reverse pattern). After induction and intubation, anesthesia was maintained with 50% N2O/O2 and desflurane (4%-6%) plus fentanyl titration to maintain an optimal respiratory rate between 10 and 16/min. Starting with the first circuit, all the patients were spontaneously breathing with a FGF of 4 L/min for 10 min, gradually decreased by 0.5 L/min every 5 min until FGF was 2.5 L/min. End-tidal CO2, inspired minimum CO2 (ImCO2), mean arterial pressure, and oxygen saturation were recorded until rebreathing (ImCO2 >0 mmHg) occurred. The alternate anesthesia breathing circuit was used and the measurements were repeated. RESULTS: The respective minimal FGF at the point of rebreathing for the Lack-Plus and Lack's circuit was 2.7±0.8 and 3.3±0.5 L/min, respectively, p<0.001. At an FGF of 2.5 L/min, the respective ImCO2 was 1.5±2.0 and 4.2±2.6 mmHg, respectively, p<0.001. CONCLUSION: The Lack-Plus circuit can be used safely and effectively, and it requires less FGF than Lack's circuit in spontaneously breathing anesthetized adults.