Objective: In this study, we aimed to investigate the effect of ultrasonograpy (USG) guided interscalene brachial plexus block on pulmonary functions and arterial blood gas analysis.

Material and Method: The study was carried out with 64 patients who were planned to undergo shoulder and upper arm surgery and had no pulmonary dysfunction with ASA I-II and surgery time not exceeding 2 hours. USG-guided interscalene brachial plexus block procedure (baseline, T0) and 20 minutes after block (T20) was performed to provide anesthesia during surgery. Heart rate, systolic, diastolic and mean arterial pressure was recorded after block procedure. Spirometry and arterial blood gas analysis were performed to evaluate the effect of interschalen block on pulmonary functions and arterial blood gas. In addition, data related to block application were recorded.

Results: A decrease in heart rate (p =0.003), systolic (p =0.375), diastolic (p =0.608) and mean arterial pressure (p =0.496) was observed at the 20th min (T20) after the block. In the second (T20) spirometric measurement performed at the 20th minute after block, compared to baseline (T0), vital capacity (VC) (4.86- 3.68, p <0.001), forced vital capacity (FVC), forced expiratory volume 1.sec (FEV1) (4.24-3.40, p <0.018), Sniff PmaxPeak (6.18-5.06, p <0.001) and significant decrease in PaO2 (86.40-79.24, p <0,024) was observed. However, the average PaCO2 (38.62-42.34, p <0.001) increase was not significant. After the block, Horner syndrome findings were observed in 12 patients, and hypotension-bradycardia was observed in 6 patients. Hoarseness developed in 4 patients.

Conclusion: Interscalene brachial plexus affects respiratory function and arterial oxygen pressure by causing unilateral hemidiaphragmatic paresis and is therefore risky for patients with pulmonary disease or cardiac pathology.