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Early Detection and Temporal Progression of Hemidiaphragmatic Paralysis After Supraclavicular Brachial Plexus Block
Xiuxia Bao1, Zonghong He2, Yun Ma1
1Department of Anesthesiology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, People's Republic of China.
Objective:
Hemidiaphragmatic paralysis (HDP) is a recognized complication of supraclavicular brachial plexus block (SCBPB). This study aimed to compare the incidence and temporal progression of HDP following ultrasound-guided SCBPB with 20 mL versus 30 mL of 0.375% ropivacaine.
Methods:
Eighty-two patients undergoing removal of internal fixation devices in the upper extremities were randomly allocated to receive 20 mL (Group A) or 30 mL (Group B) of 0.375% ropivacaine for ultrasound-guided SCBPB. The diaphragmatic compound muscle action potential amplitude (Dia CMAP Amp) was measured before (T0) and 5 min (T1), 10 min (T2), 20 min (T3), and 30 min (T4) after SCBPB. The primary outcome was the incidence of HDP, defined as a ≥50% decrease in the Dia CMAP Amp from baseline. The secondary outcome was the Dia CMAP Amp at different times.
Results:
The risk of HDP was significantly greater in Group B than in Group A (RR=1.972, P=0.011). There was a significant time effect on the incidence of HDP (Wald's χ2=15.547, P=0.001); HDP could occur within 5 minutes, and the incidence of HDP at T2, T3 and T4 was 1.222 (P=0.046), 1.889 (P<0.001) and 1.944 P<0.001) times greater than that at T1, respectively. The Dia CMAP Amp following SCBPB was significantly different between the ropivacaine groups (Wald's χ2=5.517, p=0.019).
Conclusion:
HDP can be detected as early as 5 minutes after SCBPB, with incidence plateauing by 20 minutes while CMAP amplitude continues declining. Higher volume (30 mL) nearly doubles HDP risk (RR=1.972). Respiratory monitoring should begin within 5 minutes of block placement.
