Background: Robot-assisted laparoscopic radical prostatectomy requires general anaesthesia, extreme Trendelenburg positioning and capnoperitoneum. Together these promote impaired pulmonary gas exchange caused by atelectasis and may contribute to postoperative pulmonary complications. In morbidly obese patients, a recruitment manoeuvre (RM) followed by individualised PEEP improves intraoperative oxygenation and end-expiratory lung volume (EELV). We hypothesised that individualised PEEP with initial RM similarly improves intraoperative oxygenation and EELV in nonobese individuals undergoing robot-assisted prostatectomy. Methods: Forty males (age, 49e76 yr; BMI <30 kg m À2 ) undergoing prostatectomy received volume-controlled ventilation (tidal volume 8 ml kg À1 predicted body weight). Participants were randomised to either (1) RM followed by individualised PEEP (RM/PEEP IND ) optimised using electrical impedance tomography or (2) no RM with 5 cm H 2 O PEEP. The primary outcome was the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO 2 /F i O 2 ) before the last RM before extubation. Secondary outcomes included regional ventilation distribution and EELV which were measured before, during, and after anaesthesia. The cardiovascular effects of RM/PEEP IND were also assessed. Results: In 20 males randomised to RM/PEEP IND , the median PEEP IND was 14 cm H 2 O [inter-quartile range, 8e20]. The PaO 2 / F i O 2 was 10.0 kPa higher with RM/PEEP IND before extubation (95% confidence interval [CI], 2.6e17.3 kPa; P¼0.001). RM/ PEEP IND increased end-expiratory lung volume by 1.49 L (95% CI, 1.09e1.89 L; P<0.001). RM/PEEP IND also improved the regional ventilation of dependent lung regions. Vasopressor and fluid therapy was similar between groups, although 13 patients randomised to RM/PEEP IND required pharmacological therapy for bradycardia. Conclusion: In non-obese males, an individualised ventilation strategy improved intraoperative oxygenation, which was associated with higher end-expiratory lung volumes during robot-assisted laparoscopic prostatectomy. Clinical trial registration: DRKS00004199 (German clinical trials registry)
After 15 min, PEEP was set to 15 cm H 2 O, and these measurements were repeated. Baseline characteristics were median age of 65 (56e69) yr, BMI 27 (25e30) kg m À2 , and Pa O2 /FiO 2 108 (82e141) mm Hg with a clinical PEEP of 10 (10e12) cm H 2 O. Respiratory mechanics and gas exchange data at 5 and 15 cm H 2 O of PEEP are reported in Table 1. At 15 cm H 2 O of PEEP, the driving pressure, lung elastance, and end-inspiratory transpulmonary pressure significantly increased compared with 5 cm H 2 O of PEEP. Arterial oxygenation also significantly increased without change in arterial carbon dioxide. Our results show that increasing PEEP from a low (5 cm H 2 O) to higher (15 cm H 2 O) level led to significant deterioration in lung mechanics in critically ill COVID-19 patients. In addition, at 15 cm H 2 O of PEEP, end-inspiratory transpulmonary pressure was dangerously close to the physiological limit of 20e25 cm H 2 O. These data suggest that the lung in COVID-19 is particularly prone to over-distension and to ventilatorinduced lung injury. In this regard, oesophageal manometry represents an invaluable tool in the ventilatory management of CARDS , allowing computation of the partitioned respiratory mechanics between lung and chest wall. Although standard ventilatory management would imply use of conventional PEEP/FiO 2 tables with resulting high PEEP levels caused by the severity of hypoxaemia in COVID-19 patients, our data support use of a PEEP trial and with oesophageal manometry to provide an individualised ventilatory strategy.
Background: Cardiac arrest is a critical event requiring adequate and timely response in order to increase patient's chance of survival. In patients mechanically ventilated with advance airways cardiopulmonary resuscitation (CPR) maneuver may be simplified by keeping the ventilator on. This work assessed the response of a intensive care mechanical ventilator to CPR using a patient manikin ventilated in three conventional modes. Methods: Volume controlled (VCV), pressure controlled (PCV) and pressure regulated volume controlled (PRVC) ventilation were applied in a thorax physical model with or without chest compressions. The mechanical ventilator was set with inspiratory time of 1.0 s, ventilation rate of 10 breaths/minute, positive end-expiratory pressure of 0 cmH2O, FiO2 of 1.0, target tidal volume of 600 ml and trigger level of -20 cmH2O. Airway opening pressure and ventilatory flow signals were continuously recorded. . Results: Chest compression resulted in increased airway peak pressure in all ventilation modes ( p<0.001 ), specially with VCV (137% in VCV, 83% in PCV, 80% in PRVC). However, these pressures were limited to levels similar to release valves in manual resuscitators (~60 cmH 2 O). In pressure controlled modes tidal/minute volumes decreased (PRVC=11%, p=0.027 and PCV=12%, p<0.001), while still within the variability observed during bag-valve-mask ventilation. During VCV, variation in tidal/minute volumes were not significant (p=0.140). Respiratory rates were constant with and without chest compression. Conclusions: A intensive care mechanical ventilator could provide adequate ventilation during compressions in a manikin model while using conventional ventilation modes.
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