Respiratory depression following cesarean section with single-shot spinal with 100 μg morphine

Little evidence is available regarding bradypnea measured using continuous monitoring following cesarean section. We aimed to evaluate the rate of cumulative bradypnea time (total bradypnea time/total monitoring time) and its related factors in these parturients.

This prospective observational study included women undergoing cesarean section under single-shot spinal anesthesia of 0.1 mg morphine. The Berlin Questionnaire was used to screen for sleep apnea syndrome preoperatively. Respiratory rate and oxygen saturation (SpO₂) were monitored continuously using an adhesive acoustic respiration sensor and pulse oximeter, respectively, at least 6 h after cesarean section. Bradypnea was defined as a respiratory rate < 8 breaths/min lasting at least 25 s (sustained bradypnea) or at least 15 s (immediate bradypnea). Hypoxemia was defined as SpO₂ < 92% lasting at least 25 s (sustained hypoxemia) or at least 15 s (immediate hypoxemia). Multiple regression analysis was applied to assess factors related to the rate of cumulative sustained bradypnea.

Of 159 patients, the Berlin Questionnaire was positive in 16.3%, and 77 (48.4%) experienced sustained bradypnea. The median rate of cumulative sustained bradypnea time was 0.70% (interquartile range 0.35-1.45%) without any related factors. The incidence of immediate bradypnea and sustained and immediate hypoxemia were 58.5%, 24.5%, and 37.7%, respectively. However, none of the factors were significant.

After cesarean section was performed with 0.1 mg intrathecal morphine, respiratory depression events were commonly observed. However, the rate of cumulative bradypnea time was very low and there were no related factors.