Incidence,characteristics and risk factors for alveolar recruitment maneuver-related hypotension in patients undergoing laparoscopic colorectal cancer resection

BACKGROUND Alveolar recruitment maneuvers(ARMs)may lead to transient hypotension,but the clinical characteristics of this induced hypotension are poorly understood.We investigated the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.AIM To investigate the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.METHODS This was a secondary analysis of the PROtective Ventilation using Open Lung approach Or Not trial and included 140 subjects.An ARM was repeated every 30 min during intraoperative mechanical ventilation.The primary endpoint was ARM-related hypotension,defined as a mean arterial pressure(MAP)<60 mmHg during an ARM or within 5 min after an ARM.The risk factors for hypotension were identified.The peri-ARM changes in blood pressure were analyzed for the first three ARMs(ARM_(1,2,3))and the last ARM(ARMl_(ast)).RESULTS Thirty-four subjects(24.3%)developed ARM-related hypotension.Of all 1027 ARMs,37(3.61%)induced hypotension.More ARMs under nonpneumoperitoneum(33/349,9.46%)than under pneumoperitoneum conditions(4/678,0.59%)induced hypotension(P<0.01).The incidence of hypotension was higher at ARM_(1)points than at non-ARM_(1)points(18/135,13.3%vs 19/892,2.1%;P<0.01).The median percentage decrease in the MAP at ARM1 was 14%.Age≥74 years,blood loss≥150 mL and peak inspiratory pressure under pneumoperitoneum<24 cm H_(2)O were risk factors for ARM-related hypotension.CONCLUSION When the ARM was repeated intraoperatively,a quarter of subjects developed ARM-related hypotension,but only 3.61%of ARMs induced hypotension.ARM-related hypotension most occurred in a hemodynamically unstable state or a hypovolemic state,and in elderly subjects.Fortunately,ARMs that were performed under pneumoperitoneum conditions had less impact on blood pressure.

Evolution of respiratory system compliance and potential for lung recruitment in COVID-19–induced acute respiratory distress syndrome

Background:Coronavirus disease 2019(COVID-19)has been frequently complicated by severe acute respiratory distress syndrome(ARDS)with prolonged invasive ventilation.While respiratory system compliance and lung recruitability have been described within the first days after ICU admission,data about their longitudinal changes are still limited.Therefore,we conducted this study to assess the evolution of respiratory system compliance and lung recruitability in patients with COVID-19–related ARDS.Method:We conducted a prospective single-center study in patients admitted for COVID-19–related ARDS during the first wave of the pandemic,from March 16,2020 to April 10,2020.Respiratory system compliance was calculated daily at clinical positive end-expiratory pressure(PEEP)during passive breathing.The potential for lung recruitment was assessed by measuring the volume derecruited between PEEP 15 cmH2 O and 5 cmH2 O,and using the calculation of the recruitment-to-inflation ratio(R/I ratio).Recruitable lung was considered when the R/I ratio was at least 0.5.The primary outcome was the evolution of respiratory mechanics over time.The secondary outcome was the evolution of lung recruitability over time.Results:Thirty-two patients were included in this study.The respiratory mechanics were assessed 222 times(7±5 times per patient).Respiratory system compliance at clinical PEEP was 29.1 mL/cmH2 O(interquartile range[IQR]:24.1–33.9 mL/cmH2 O)and decreased significantly over time(P<0.0001).Lung recruitability was assessed in 22 out of the 32 patients(60 assessments).The median volume derecruited between PEEP 15 cmH2 O and 5 cmH2 O was 246.8 mL(IQR:180.8–352.2 mL)and the median R/I ratio was 0.56(IQR:0.39–0.73).Neither changed significantly over time.The proportion of patients with recruitable lung was 50.0%(6/12)within the first 3 days after intubation,69.2%(9/13)between day 4 and day 7,and 66.7%(8/12)after day 7(P=0.7934).Conclusions:In our cohort,respiratory system compliance was low and decreased over time.The potential for lung recruitment was high and persisted despite prolonged mechanical ventilation,suggesting that maintaining high PEEP levels in the later course of COVID-19 could be adequate.