[Evaluation of diaphragmatic paralysis with ultrasound and spirometry: comparison of supraclavicular vs interscalene block in shoulder surgery].

Introduction: arthroscopic shoulder surgery has recently gained popularity, however, postoperative pain is reported as moderate to severe. Regional anesthesia is useful for the control of postoperative pain. Interscalene and supraclavicular blocks produce diaphragmatic paralysis in different proportions. The aim of this study is to find the percentage and duration of hemidiaphragmatic paralysis, by means of ultrasonographic measurements, correlated with spirometry, comparing the supraclavicular approach with interscalene.

Material and methods: clinical, controlled and randomized trial. Fifty-two patients, between 18 and 90 years of age, scheduled for arthroscopic shoulder surgery were included, divided into 2 groups (interscalene or supraclavicular block). Diaphragmatic excursion was measured and spirometry was performed prior to admission to the operating room and 24 hours after installation of the block, the study concluded 24 hours after the anesthetic event.

Results: vital capacity was reduced by 0.7% in the supraclavicular block and 7.7% for the interscalene, FEV1 was reduced by 0.2% for the supraclavicular and 9.5% in the interscalene with a statistically significant difference (p = 0.001). Diaphragmatic paralysis in spontaneous ventilation appeared in both approaches at 30 minutes, without significant difference. At 6 and 8 hours, paralysis continued in the interscalene group, while in the supraclavicular approach it remained preserved compared to the baseline.

Conclusions: supraclavicular block is as effective as interscalene block in arthroscopic shoulder surgery, with less diaphragmatic block (1.5 times more diaphragmatic paralysis in interscalene).