Nocturnal body movements and hypoxemia in middle-aged females after lower abdominal surgery under general anesthesia: a study with the static-charge-sensitive bed (SCSB).

OBJECTIVE

The aim of this study was to evaluate the feasibility of the static-charge-sensitive-bed (SCSB) combined with pulse oximetry (SpO2) for postoperative monitoring and to determine variables which could be used for evaluating the quality of postoperative sleep and breathing.

METHODS

The frequency of body movements and the perioperative breathing abnormalities were assessed using the SCSB and pulse oximeter in 15 female ASA-class I-II patients undergoing elective lower abdominal surgery under general anesthesia. Anesthesia and control of postoperative pain followed standard practice. The patients were monitored during one preoperative and three consecutive postoperative nights. Movements were analyzed according to their duration and time interval. The effect of opioids was evaluated by measuring arterial oxyhemoglobin saturation (SpO2) with pulse oximetry for one hour before and two hours after administration of standard doses of oxycodone.

RESULTS

The total movement time per hour increased during the first postoperative night (p = 0.003). Conversely, periodic movement activity decreased significantly during the three postoperative nights (p = 0.05, p < 0.001, p = 0.007). The mean SpO2 decreased during the first postoperative night (95.5% vs. 94.2%, p = 0.002), but returned to the preoperative level during the following nights. No episodes of apnea with significant oxygen desaturation (a decrease in SpO2 > 5%) were observed. Opioid administration was associated with decreased mean SpO2 (94.8% vs. 93.6%, p = 0.02), but did not lead to clinically significant hypoxemia (lowest observed SpO2 89.8%).

CONCLUSIONS

Postoperative periodic movement activity was suppressed, but sleep remained fragmented with frequent body movements. In our middle-aged non-obese females (ASA I-II), no severe postoperative hypoxemia was observed during the three-nights postoperative survey. Perioperative movement monitoring with the SCSB was a valuable tool in rejecting movement artefacts of SpO2 and in evaluating general sleep quality.