Adverse Events of Peripherally Administered Norepinephrine During Surgery: A Prospective Multicenter Study.

BACKGROUND: Perioperative treatment of hypotension by intravenous administration of norepinephrine in a peripheral vein can lead to adverse events, for example, tissue necrosis. However, the incidence and severity of adverse events during perioperative administration are unknown. METHODS: This was a prospective observational study conducted at 3 Swedish hospitals from 2019 to 2022. A total of 1004 patients undergoing surgery, who met the criteria for perioperative peripheral norepinephrine administration, were included. The infusion site was inspected regularly. If swelling or paleness of skin was detected, the infusion site was changed to a different peripheral line. Systolic blood pressure and pulse frequency were monitored during the infusion time and defined as adverse events at >220 mm Hg and <40 beats•min -1 . In case of adverse events, patients were observed for up to 48 hours. The primary outcome was prevalence of extravasation, defined as swelling around the infusion site. Secondary outcomes were all types of adverse events and associations between predefined clinical variables and risk of adverse events. RESULTS: We observed 2.3% (95% confidence interval [CI], 1.4%-3.2%) extravasation of infusion and 0.9% (95% CI, 0.4%-1.7%) bradycardia. No cases of tissue necrosis or severe hypertension were detected. All adverse events had dissipated spontaneously within 48 hours. Proximal catheter placement was associated with more adverse events. CONCLUSIONS: Extravasation of peripherally administrated norepinephrine in the perioperative period occurred at similar rates as in previous studies in critically ill patients. In our setting, where we regularly inspected the infusion site and shifted site in case of swelling or paleness of skin, we observed no case of severe adverse events. Given that severe adverse events were absent, the potential benefit of this preventive approach requires confirmation in a larger population.

Improved oxygenation in prone positioning of mechanically ventilated patients with COVID-19 acute respiratory distress syndrome is associated with decreased pulmonary shunt fraction: a prospective multicenter study.

BACKGROUND: Prone position is used in acute respiratory distress syndrome and in coronavirus disease 2019 (Covid-19) acute respiratory distress syndrome (ARDS). However, physiological mechanisms remain unclear. The aim of this study was to determine whether improved oxygenation was related to pulmonary shunt fraction (Q's/Q't), alveolar dead space (Vd/Vtalv) and ventilation/perfusion mismatch (V'A/Q'). METHODS: This was an international, prospective, observational, multicenter, cohort study, including six intensive care units in Sweden and Poland and 71 mechanically ventilated adult patients. RESULTS: Prone position increased PaO2:FiO2 after 30 min, by 78% (83-148 mm Hg). The effect persisted 120 min after return to supine (p < 0.001). The oxygenation index decreased 30 min after prone positioning by 43% (21-12 units). Q's/Q't decreased already after 30 min in the prone position by 17% (0.41-0.34). The effect persisted 120 min after return to supine (p < 0.005). Q's/Q't and PaO2:FiO2 were correlated both in prone (Beta -137) (p < 0.001) and in the supine position (Beta -270) (p < 0.001). V'A/Q' was unaffected and did not correlate to PaO2:FiO2 (p = 0.8). Vd/Vtalv increased at 120 min by 11% (0.55-0.61) (p < 0.05) and did not correlate to PaO2:FiO2 (p = 0.3). The ventilatory ratio increased after 30 min in the prone position by 58% (1.9-3.0) (p < 0.001). PaO2:FiO2 at baseline predicted PaO2:FiO2 at 30 min after proning (Beta 1.3) (p < 0.001). CONCLUSIONS: Improved oxygenation by prone positioning in COVID-19 ARDS patients was primarily associated with a decrease in pulmonary shunt fraction. Dead space remained high and the global V'A/Q' measure could not explain the differences in gas exchange.