Comparison of Efficacy of Spontaneous Breathing with Pressure Support and Volume-Controlled Mandatory Ventilation during General Combined Anesthesia without Muscle Relaxants

Abstract

To compare efficacy of spontaneous breathing with pressure support and volume-controlled mandatory ventilation during combined general anesthesia using desflurane and without muscle relaxants.Subjects and Methods. 100 patients were included in the study. All underwent low-traumatic operations on the lower limbs under general combined anesthesia using supraglottic air devices without muscle relaxants. Immediately prior to the induction of anesthesia, patients were randomly divided into two groups: Group 1 (VCV) where a mandatory volume control mode was used (n = 50) and Group 2 (PSV) where a pressure support mode was used (n = 50). The following parameters were assessed: hemodynamics, gas exchange, depth of anesthesia before induction, during and after the end of general anesthesia; arterial blood gas composition one hour after induction of anesthesia; indicators of pressure in the respiratory tract during mechanical ventilation, as well as time parameters of awakening.Results. In patients of Group 2 (PSV), according to the analysis of arterial blood gases, a higher level of PaO2 (p = 0.006), Horowitz index (p = 0.005), and carbon dioxide level (p < 0.0001) were noted. In Group 1 (VCV), higher mean and peak airway pressures were found one hour after induction and 10 minutes before the end of surgery (p < 0.05). Also in the groups, there were statistically significant differences in the time parameters of awakening (233 ± 58 sec and 352 ± 83 sec in the PSV and VCV groups, respectively), supraglottic airway device removal time (268 ± 62 sec and 398 ± 84 sec in the PSV and VCV groups, respectively) and transfer to the ward (395 ± 60 sec and 571 ± 66 sec in the PSV and VCV groups, respectively) (p < 0.0001). There were no significant differences in the main parameters of hemodynamics and depth of anesthesia, the consumption of anesthetics used during induction and maintenance of general anesthesia.Conclusion: The use of spontaneous breathing with pressure support during general combined anesthesia without muscle relaxants has a number of advantages versus mandatory ventilation mode. These include better oxygenation rates, lower airway pressure, faster awakening, supraglottic airway device removal time, and transfer of the patient to the ward. At the same time, acceptable ventilation, stable hemodynamic parameters and depth of anesthesia are maintained.

Keywords

• general anesthesia
• supraglottic airway device
• laryngeal mask
• mechanical ventilation
• pressure support ventilation
• gas exchange
• awakening