Global and Regional Respiratory Mechanics During Robotic-Assisted Laparoscopic Surgery: A Randomized Study

Abstract

BACKGROUND: Pneumoperitoneum and nonphysiological positioning required for robotic surgery increase cardiopulmonary risk because of the use of larger airway pressures (Paws) to maintain tidal volume (Vt). However, the quantitative partitioning of respiratory mechanics and transpulmonary pressure (Pl) during robotic surgery is not well described. We tested the following hypothesis: (1) the components of driving pressure (transpulmonary and chest wall components) increase in a parallel fashion at robotic surgical stages (Trendelenburg and robot docking); and (2) deep, when compared to routine (moderate), neuromuscular blockade modifies those changes in Pls as well as in regional respiratory mechanics. METHODS: We studied 35 American Society of Anesthesiologists (ASA) I-II patients undergoing elective robotic surgery. Airway and esophageal balloon pressures and respiratory flows were measured to calculate respiratory mechanics. Regional lung aeration and ventilation was assessed with electrical impedance tomography and level of neuromuscular blockade with acceleromyography. During robotic surgical stages, 2 crossover randomized groups (conditions) of neuromuscular relaxation were studied: Moderate (1 twitch in the train-of-four stimulation) and Deep (1–2 twitches in the posttetanic count). RESULTS: Pneumoperitoneum was associated with increases in driving pressure, tidal changes in Pl, and esophageal pressure (Pes). Steep Trendelenburg position during robot docking was associated with further worsening of the respiratory mechanics. The fraction of driving pressures that partitioned to the lungs decreased from baseline (63% ± 15%) to Trendelenburg position (49% ± 14%, P < .001), due to a larger increase in chest wall elastance (Ecw; 12.7 ± 7.6 cm H2O·L−1) than in lung elastance (El; 4.3 ± 5.0 cm H2O·L−1, P < .001). Consequently, from baseline to Trendelenburg, the component of Paw affecting the chest wall increased by 6.6 ± 3.1 cm H2O, while Pls increased by only 3.4 ± 3.1 cm H2O (P < .001). Pl and driving pressures were larger at surgery end than at baseline and were accompanied by dorsal aeration loss. Deep neuromuscular blockade did not change respiratory mechanics, regional aeration and ventilation, and hemodynamics. CONCLUSIONS: In robotic surgery with pneumoperitoneum, changes in ventilatory driving pressures during Trendelenburg and robot docking are distributed less to the lungs than to the chest wall as compared to routine mechanical ventilation for supine patients. This effect of robotic surgery derives from substantially larger increases in Ecw than Els and reduces the risk of excessive Pls. Deep neuromuscular blockade does not meaningfully change global or regional lung mechanics.

Driving Pressure and Transpulmonary Pressure

“…2B). 53 Direct human data in these conditions to provide quantification of the distribution of airway pressures to the lungs and chest wall have only recently been presented. 53 Measurements of transpulmonary pressure have highlighted the possibility of distinct lung stresses during experimental intraabdominal hypertension.…”

“…53 Direct human data in these conditions to provide quantification of the distribution of airway pressures to the lungs and chest wall have only recently been presented. 53 Measurements of transpulmonary pressure have highlighted the possibility of distinct lung stresses during experimental intraabdominal hypertension. 48,54 Increasing intraabdominal pressure increased plateau pressure by about half of the applied intraabdominal pressure, but produced minimal change in transpulmonary pressure in healthy lungs, emphasizing that airway pressures do not reflect transpulmonary pressures.…”

Intraoperative Driving Pressure and Postoperative Pulmonary Complications After Abdominal Surgery – A Posthoc Propensity Score–Weighted Cohort Analysis of the LAS VEGAS Study Comparing Open to Closed Surgery

“…Pneumoperitoneum was consistently found to decrease chest wall compliance, whereas lung compliance seems mostly spared by it. [20][21][22][23][24][25][26][27] Thus, inferring the amount of lung strain from plateau pressure and PEEP during pneumoperitoneum is challenging, since the part of the rise in plateau pressure caused by chest wall stiffening should not intensify lung it. [28] Consequently, a higher driving pressure during closed abdominal surgery could be less harmful or even 'non-injurious'.…”

“…Indeed, pneumoperitoneum can affect lung mechanics in several ways. [20][21][22][23][24][25][26][27] A cranial shift of the diaphragm during laparoscopic surgery increases alveolar collapse, especially in lung parts close to the diaphragm. This is particularly true in upper abdominal surgery, which was the most common surgical procedure in patients undergoing closed surgery in the here studied cohort.…”

Journal of Clinical Monitoring and Computing 2018–2019 end of year summary: respiration

“…For patients with high pulmonary pressures due to increases in abdominal pressure, it is likely that transpulmonary pressure represents a more accurate measurement of the potential damage to the lungs. It has recently been shown that for surgical procedures such as those reported by Blecha et al, that only 50% of the increased driving pressure is seen by the lungs as increased transpulmonary pressure [50], supporting the case for use of esophageal pressure measurements to monitor pulmonary mechanics in such patients.…”