Respiratory effects of lung recruitment maneuvers depend on the recruitment-to-inflation ratio in patients with COVID-19-related acute respiratory distress syndrome

Background In the context of acute respiratory distress syndrome (ARDS), the response to lung recruitment maneuvers (LRMs) varies considerably from one patient to another and so is difficult to predict. The aim of the study was to determine whether or not the recruitment-to-inflation (R/I) ratio could differentiate between patients according to the change in lung mechanics during the LRM. Methods We evaluated the changes in gas exchange and respiratory mechanics induced by a stepwise LRM at a constant driving pressure of 15 cmH2O during pressure-controlled ventilation. We assessed lung recruitability by measuring the R/I ratio. Patients were dichotomized with regard to the median R/I ratio. Results We included 30 patients with moderate-to-severe ARDS and a median [interquartile range] R/I ratio of 0.62 [0.42–0.83]. After the LRM, patients with high recruitability (R/I ratio ≥ 0.62) presented an improvement in the PaO2/FiO2 ratio, due to significant increase in respiratory system compliance (33 [27–42] vs. 42 [35–60] mL/cmH2O; p < 0.001). In low recruitability patients (R/I < 0.62), the increase in PaO2/FiO2 ratio was associated with a significant decrease in pulse pressure as a surrogate of cardiac output (70 [55–85] vs. 50 [51–67] mmHg; p = 0.01) but not with a significant change in respiratory system compliance (33 [24–47] vs. 35 [25–47] mL/cmH2O; p = 0.74). Conclusion After the LRM, patients with high recruitability presented a significant increase in respiratory system compliance (indicating a gain in ventilated area), while those with low recruitability presented a decrease in pulse pressure suggesting a drop in cardiac output and therefore in intrapulmonary shunt.

The Effect of Ultrasound-Guided Lung Recruitment Maneuvers On Atelectasis In Lung-Healthy Patients Undergoing Laparoscopic Gynecologic Surgery: a Randomized Controlled Trial

BackgroundAtelectasis is a major cause of hypoxemia during general anesthesia and postoperative pulmonary complications (PPCs).Some previous reported that the combined use of lung recruitment procedures (LRMs) and positive end-expiratory pressure (PEEP) in mechanical ventilation mode contributes to the avoidance of PPCs in patients after general anesthesia, while others suggest that the use of LRMs makes patients more susceptible to hemodynamic disturbances and lung injury, and is of limited potential to decrease the incidence of PPCs. From this perspective, controversy exists as to whether LRMs should be routinely applied to surgical patients. More importantly, corresponding clinical studies are also lacking. Therefore, this trial was conducted with the aim of solving the above problem.MethodsIn current clinical trial, patients undergoing laparoscopic gynecologic surgery with healthy lungs were randomized to the recruitment maneuvers group (RM group; 6 cm H2O PEEP and RMs) and the control group (C group; 6 cm H2O PEEP and no RMs). Lung ultrasound was performed on patients at five separate time points. During mechanical ventilation, patients in the RM group received ultrasound-guided pulmonary resuscitation when atelectasis was detected, while the C group did not intervene. Lung ultrasound scores were used to evaluate the incidence and severity of atelectasis.ResultsAfter LRMs, the incidence of atelectasis was significantly lower in the RM group (40%) than in the C group (80%) 15 minutes after arrival in the post-anesthesia care unit (PACU), and this difference did not persist for 24 hours after surgery. Meanwhile, postoperative pulmonary complications showed no difference between the two groups.ConclusionsThe combination of LRMs and PEEP decreased the incidence of atelectasis 15 minutes after admission to the PACU, but did not improve PPCs in adults with healthy lungs. Hence, for lung-healthy patients undergoing gynecological laparoscopic surgery, we do not recommend routine recruitment maneuvers. Trial registration: (prospectively registered): ChiCTR2000033529. Registered on 6/4/2020.

Effect of Ultrasound-guided Lung Recruitment Maneuvers on Atelectasis in Lung-healthy Patients Undergoing Laparoscopic Gynecologic Surgery: a Randomized Controlled Trial

BackgroundAtelectasis is a major cause of hypoxemia during general anesthesia and postoperative pulmonary complications (PPCs).Some previous reported that the combined use of lung recruitment procedures (LRMs) and positive end-expiratory pressure (PEEP) in mechanical ventilation mode contributes to the avoidance of PPCs in patients after general anesthesia, while others suggest that the use of LRMs makes patients more susceptible to hemodynamic disturbances and lung injury, and is of limited potential to decrease the incidence of PPCs. From this perspective, controversy exists as to whether LRMs should be routinely applied to surgical patients. More importantly, corresponding clinical studies are also lacking. Therefore, this trial was conducted with the aim of solving the above problem.MethodsIn current clinical trial, patients undergoing laparoscopic gynecologic surgery with healthy lungs were randomized to the recruitment maneuvers group (RM group; 6 cm H2O PEEP and RMs) and the control group (C group; 6 cm H2O PEEP and no RMs). Lung ultrasound was performed on patients at five separate time points. During mechanical ventilation, patients in the RM group received ultrasound-guided pulmonary resuscitation when atelectasis was detected, while the C group did not intervene. Lung ultrasound scores were used to evaluate the incidence and severity of atelectasis.ResultsAfter LRMs, the incidence of atelectasis was significantly lower in the RM group (40%) than in the C group (80%) 15 minutes after arrival in the post-anesthesia care unit (PACU), and this difference did not persist for 24 hours after surgery. Meanwhile, postoperative pulmonary complications showed no difference between the two groups.ConclusionsThe combination of LRMs and PEEP decreased the incidence of atelectasis 15 minutes after admission to the PACU, but did not improve PPCs in adults with healthy lungs. Hence, for lung-healthy patients undergoing gynecological laparoscopic surgery, we do not recommend routine recruitment maneuvers. Trial registration (prospectively registered)ChiCTR2000033529. Registered on June 4, 2020.

Practical Review of Mechanical Ventilation in Adults and Children in The Operating Room and Emergency Department

Background: During general anesthesia, mechanical ventilation can cause pulmonary damage through mechanism of ventilator-induced lung injury which is a major cause of postoperative pulmonary complications, which varies between 5 and 33% and increases significantly the 30-day mortality of the surgical patient. Objective: The aim of this review is to analyze different variables which played key role in safe application of mechanical ventilation in the operating room and emergency setting. Method: Also, we wanted to analyze different types of population that underwent intraoperative mechanical ventilation like obese patients, pediatric and adult population and different strategies such as one lung ventilation and ventilation in trendelemburg position. The peer-reviewed articles analyzed were selected according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) from Pubmed/Medline, Ovid/Wiley and Cochrane Library, combining key terms such as: “pulmonary post-operative complications”, “protective ventilation”, “alveolar recruitment maneuvers”, “respiratory compliance”, “intraoperative paediatric ventilation”, “best peep”, “types of ventilation”. Among the 230 papers identified, 150 articles were selected, after title - abstract examination and removing the duplicates, resulting in 94 articles related to mechanical ventilation in operating room and emergency setting that were analyzed. Results: Careful preoperative patient’s evaluation and protective ventilation (i.e. use of low tidal volumes, adequate PEEP and alveolar recruitment maneuvers) has been shown to be effective not only in limiting alveolar de-recruitment, alveolar overdistension and lung damage, but also in reducing the onset of pulmonary post-operative complications (PPCs). Conclusion: Mechanical ventilation is like “Janus Bi-front” because it is essential for surgical procedures, for the care of critical care patients and in life-threatening conditions but it can be harmful to the patient if continued for a long time and where an excessive dose of oxygen is administered into the lungs. Low tidal volume is associated with minor rate of PPCs and other complications and every complication can increase length of Stay, adding cost to NHS between 1580 € and 1650 € per day in Europe and currently the prevention of PPCS is only weapon that we possess.

Lung Ultrasonography in the Monitoring of Intraoperative Recruitment Maneuvers

Introduction: Postoperative respiratory failure is a serious problem in patients who undergo general anesthesia. Approximately 90% of mechanically ventilated patients during the surgery may develop atelectasis that leads to perioperative complications. Aim: The aim of this study is to determine whether it is possible to optimize recruitment maneuvers with the use of chest ultrasonography, thus limiting the risk of respiratory complications in patients who undergo general anesthesia. Methodology: The method of incremental increases in positive end-expiratory pressure (PEEP) values with simultaneous continuous ultrasound assessments was employed in mechanically ventilated patients. Results: The study group comprised 100 patients. The employed method allowed for atelectasis reduction in 91.9% of patients. The PEEP necessary to reverse areas of atelectasis averaged 17cmH2O, with an average peak pressure of 29cmH2O. The average PEEP that prevented repeat atelectasis was 9cmH2O. A significant improvement in lung compliance and saturation was obtained. Conclusions: Ultrasound-guided recruitment maneuvers facilitate the patient-based adjustment of the process. Consequently, the reduction in ventilation pressures necessary to aerate intraoperative atelectasis is possible, with the simultaneous reduction in the risk of procedure-related complications.

ALVEOLAR RECRUITMENT MANEUVERS FOR CHILDREN WITH CANCER AND ACUTE RESPIRATORY DISTRESS SYNDROME: A FEASIBILITY STUDY

ABSTRACT Objective: Acute respiratory distress syndrome (ARDS) can be a devastating condition in children with cancer and alveolar recruitment maneuvers (ARMs) can theoretically improve oxygenation and survival. The study aimed to assess the feasibility of ARMs in critically ill children with cancer and ARDS. Methods: We retrospectively analyzed 31 maneuvers in a series of 12 patients (median age of 8.9 years) with solid tumors (n=4), lymphomas (n=2), acute lymphoblastic leukemia (n=2), and acute myeloid leukemia (n=4). Patients received positive end-expiratory pressure from 25 up to 40 cmH20, with a delta pressure of 15 cmH2O for 60 seconds. We assessed blood gases pre- and post-maneuvers, as well as ventilation parameters, vital signs, hemoglobin, clinical signs of pulmonary bleeding, and radiological signs of barotrauma. Pre- and post-values were compared by the Wilcoxon test. Results: Median platelet count was 53,200/mm3. Post-maneuvers, mean arterial pressure decreased more than 20% in two patients, and four needed an increase in vasoactive drugs. Hemoglobin levels remained stable 24 hours after ARMs, and signs of pneumothorax, pneumomediastinum, or subcutaneous emphysema were absent. Fraction of inspired oxygen decreased significantly after ARMs (FiO2; p=0.003). Oxygen partial pressure (PaO2)/FiO2 ratio increased significantly (p=0.0002), and the oxygenation index was reduced (p=0.01), but all these improvements were transient. Recruited patients’ 28-day mortality was 58%. Conclusions: ARMs, although feasible in the context of thrombocytopenia, lead only to transient improvements, and can cause significant hemodynamic instability.