Monitoring: Equipment and Computers
Background and Goal of Study: Resorption of CO2 during laparoscopic surgery may have detrimental cardiovascular effects, especially in morbidly obese patients (MOP). The aim of this study is to determine the increase in minute ventilation (MV) required to maintain the normocapnia in MOP undergoing laparoscopic bariatric surgery.
Materials and Methods: 15 ASA physical class 2 MOP (BMI > 40) were studied. Furthermore 10 normal weight patients (control group = c) undergoing laparoscopic cholecystectomy was enrolled. The anaesthetic regimen was standard. All the patients were ventilated with a tidal volume 8-10 ml/Kg (ideal body weight). Respiratory rate (RR) was adjusted to maintain an ETCO2 near 35 mmHg. The measurements of arterial blood gas tensions were made after tracheal intubation (1), 15′ after the beginning of pneumoperitoneum (PNP) (2), and then every 30′ until desufflation. RR was increased after abdominal insufflation in order to maintain ETCO2 and paCO2 at or near baseline values. Abdominal pressure was setted at 12 mmHg. Statical analysis was performed by ANOVA for repeated measures.
Results and Discussions: Main intra-operative data are presented in Table.
Conclusion: Although possible detrimental changes in respiratory function, MOP doesn't require higher increase in VM to maintain normocapnia compared to normal-weight patients (18.5% ± 2 vs 16% ± 1.5); furthermore this ventilatory setting allowed to avoid high airway plateau pressures (paw), even if the gradient between paCO2 and ETCO2 showed a moderate increase.
1 Sprung J “The impact of morbid obesity, pneumoperitoneum, and posture on respiratory system mechanics and oxygenation during laparoscopic” Anest. Analg 2002; 94: 1345-50.