Mallampati Classification and Frequency of Respiratory Depression After Cesarean Section With 0.15 MG Spinal Morphine

Abstract

Background: Spinal anesthesia with intrathecal morphine is widely used for cesarean section (CS), and is associated with nocturnal desaturation. No studies have correlated respiratory depression (RD) in this population with the Mallampati (MMP) classification. We examine the value of MMP for preoperative risk stratification. Method: MMP was assessed preoperatively in patients scheduled for elective CS under spinal anesthesia. We defined RD events as follows within 24 hours postoperatively, measured by mainstream capnometry waveform analysis: 1. Bradypnea (RR ≤ 9 bpm for ≥ 120 seconds); 2. Apnea (PETCO2 < 5 mmHg for ≥ 15 seconds up to 120 seconds); 3. Temporary hypopnea (5 mmHg ≤ PETCO2 < 15 mmHg for ≥ 15 seconds up to 120 seconds); 4. Sustained hypopnea (PETCO2 > 45 mmHg for ≥ 120 seconds). Results: There were 100 patients with MMP 1-2, and 90 patients with MMP 3-4. Bradypnea was observed in 55 patients (MMP 1-2, 55%) vs. 55 patients (MMP 3-4, 61%), p = 0.394. Apnea was observed in 77 patients (MMP 1-2, 77%) vs. 75 patients (MMP 3-4, 83%), p = 0.276. Temporary hypopnea was observed in 68 patients (MMP 1-2, 68%) vs. 76 patients (MMP 3-4, 84%), p = 0.008. No sustained hypopnea events were noted in any patients. Conclusions: Temporary hypopnea was more frequent in patients with MMP 3-4 vs. 1-2, following 0.15 mg intrathecal morphine for CS. The study was registered at the University Hospital Medical Information Network Clinical Trials Registry (UMIN000031410).

Keywords

• intrathecal morphine
• mallampati classification
• cesarean section
• postoperative respiratory depression
• perioperative risk stratification