Key result
Lithotomy position during general anesthesia with LMA was associated with significantly higher mean airway pressure, plateau pressure, and expiratory resistance compared to supine position (P<0.05).
Why the study?
Does lithotomy position compared to supine position alter respiratory dynamics in patients undergoing general anesthesia with LMA?
Observational (n=90)
Does lithotomy position compared to supine position alter respiratory dynamics in patients undergoing general anesthesia with LMA?
Lithotomy position during general anesthesia with LMA significantly increases airway resistance and decreases lung compliance compared to supine position, with effects exacerbated by higher BMI.
Answers are grounded in this paper and cite their sources.
May prompt closer airway pressure monitoring with lithotomy under LMA; leaves open causal effects on outcomes.
BACKGROUND This study aimed to compare respiratory dynamics in patients undergoing general anesthesia with a laryngeal mask airway (LMA) in lithotomy and supine positions and to validate the impact of operational position on effectiveness of LMA ventilation. MATERIAL AND METHODS A total of 90 patients (age range, 18-65 years) who underwent general anesthesia were selected and divided into supine position (SP group) and lithotomy position groups (LP group). Vital signs and respiratory dynamic parameters of the 2 groups were measured at different time points and after implantation of an LMA. The arterial blood gas was monitored at 15 min after induction. The intraoperative changes of hemodynamic indexes and postoperative adverse reactions of LMA were recorded. The possible correlation between body mass index (BMI) and respiratory dynamic indexes was analyzed. RESULTS With prolonged duration of the operation, the inspiratory plateau pressure (Pplat), inspiratory resistance (RI), and work of breathing (WOB) gradually increased, while chest-lung compliance (Compl) and partial pressure of carbon dioxide in end-expiratory gas (PetCO2) gradually decreased (all P value <0.05). The mean airway pressure (Pmean), Pplat, and expiratory resistance (Re) in the LP group were significantly higher than in the SP group (P<0.05), while the peak inspiratory flow (FImax), peak expiratory flow (FEmax), WOB, and Compl in the LP group were significantly lower than in the SP group (P<0.05). BMI was positively correlated with peak airway pressure (PIP/Ppeak), Pplat, and airway resistance (Raw) and was negatively correlated with Compl; the differences among patients in lithotomy position were more remarkable (P<0.05). CONCLUSIONS The inspiratory plateau pressure and airway resistance increased with prolonged duration of the operation, accompanied by decreased chest-lung compliance. Peak airway pressure and airway resistance were positively correlated with BMI, and chest-lung compliance was negatively correlated with BMI. Changes among patients in lithotomy position were more remarkable than those in supine position.
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Zhao et al. (2016) conducted an observational in General anesthesia with laryngeal mask airway (n=90). Lithotomy position vs. Supine position was evaluated on Respiratory dynamic parameters including mean airway pressure, plateau pressure, and expiratory resistance (p=<0.05). Lithotomy position during general anesthesia with LMA was associated with significantly higher mean airway pressure, plateau pressure, and expiratory resistance compared to supine position (P<0.05).
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