Background: The spinal block has become a favorable technique for gynecologic surgery. However, the level of sympathetic blockade results in weak diaphragm and respiratory muscles as well as cough impairment. Investigators were curious to assess patients’ respiratory functions after spinal anesthesia.

Materials and Methods: One hundred forty-five gynecologic patients undergoing elective, exploratory laparotomy with spinal anesthesia were included. The blowing practice of a Mini Wright Peak Flow Meter was performed until patients became comfortable with it. A given patient blew the device three times, and the best value was chosen to assess peak expiratory flow rates (PEFRs): prior to surgery (P1), after the spinal block (P2), and in the recovery room (P3).

Results: At the thoracic blockade level as T was 4 or less and T was greater than 4, PEFR at P1, P2 and P3 were 285.9±5.9, 222.3±4.9, and 216.4±6.4 mL, and 302.8±7.7, 224.9±6.4, and 203.4±8.4 mL, respectively. The PEFRs showed no significant differences among the levels of blockade at the ward (p=0.082), the operating theater (p=0.744), and the recovery room (p=0.211). Though P3 seemed to fall, there was no marked difference between P2 and P3 (p=0.224). However, either P2 or P3 appeared to decrease sharply (p<0.001) in comparison with P1.

Conclusion: A Mini Wright Peak Flow Meter can be used as a bedside device to measure PEFRs. The substantial decrease of PEFR was related to the level of sympathetic blockade after spinal anesthesia.

Keywords: Anesthesia, Spinal block, Peak expiratory flow rate, Gynecology

DOI: doi.org/10.35755/jmedassocthai.2020.09.11186

Received 6 March 2020 | Revised 20 May 2020 | Accepted 21 May 2020