Association of Dynamometer-based Handgrip Strength with Postoperative Oxygen Requirement in Patients Undergoing General Anesthesia

Introduction: Postoperative patients who have received general anesthesia are administered oxygen therapy to prevent potential hypoxemia. Handgrip strength can be a supplemental indicator of postoperative residual muscle weakness and hence postoperative oxygen supplementation requirements. Aims: In this study, we measured voluntary muscle control using a dynamometer to detect hypoventilation due to residual neuromuscular blockade and its implication on postoperative oxygen requirements. Methodology: A prospective observational study where 50 patients were recruited. The recovery of handgrip strength, respiratory rate (RR), and SpO 2 was assessed postgeneral anesthesia at regular intervals till 6 h or till complete recovery, whichever was earliest. The duration of oxygen supplementation needed postoperatively was also noted. Results: We found that there was an increased RR immediately following surgery ( P < 0.001), with a gradual return to baseline values within 120 min ( P = 0.022), increased handgrip strength, starting at 30 min ( P < 0.001), with return to the preoperative value by 120 min ( P = 0.095). A drop in SpO 2 was noted right after surgery ( P < 0.001), with a gradual return to baseline levels by 120 min. Conclusions: Handgrip strength was negatively correlated with SpO 2 and RR, particularly in the first 120 min postoperatively, implying that weaker handgrip strength corresponds to lower oxygen levels and higher RRs and hence is a good indicator of lung function. This indicates that oxygen supplementation must be continued for at least 120 min postextubation to prevent hypoventilation.