Effect of different volumes of 0.375% ropivacaine on diaphragmatic paralysis by supraclavicular brachial plexus block under ultrasound guidance

Abstract

Background: Supraclavicular brachial plexus block (SCBPB) is a traditional anesthesia technique widely used in upper limb surgery. Ultrasound-guided SCBPB shows the peripheral structure and dynamic local anesthetic diffusion and can greatly shorten the anesthesia operation time, increase the success rate of anesthesia, and reduce the incidence of complications. However, it can still block the phrenic nerve and paralyze the diaphragm, which can be difficult to avoid. This study investigated two different volumes of the same concentration of ropivacaine used in ultrasound-guided SCBPB, and compared the effects on the incidence of diaphragmatic paralysis, pulse oxygen saturation (SpO2) and lung function in patients. Methods: The study group comprised 103 patients who were to undergo surgery on the right forearm or right hand. They were randomly divided into two groups: group A were given 20 mL 0.375% ropivacaine, and group B were given 30 mL 0.375% ropivacaine. We recorded the SpO2, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) before and 30 min after the block, and evaluated whether the patient had combined respiratory dysfunction according to the lung function indicators. We also recorded the maintenance time of anesthesia, the recovery time of motor block, and evaluated the effect of anesthesia. Results: The time to onset of motor block in group B was significantly shorter than in group A (P<0.05). After 30 min of blockade, the rate of diaphragmatic paralysis in group B under different breathing states was significantly higher than that of group A (P<0.05); after 30 min of blockade, the rate of partial paralysis of the diaphragm with forced breathing was significantly higher than the rate of partial paralysis of the diaphragm with calm breathing (P<0.05). Conclusions: Both 20 and 30 mL of 0.375% ropivacaine can achieve the ideal brachial plexus block with ultrasound-guided SCBPB, but compared with 20 mL of 0.375% ropivacaine, 30 mL of 0.375% ropivacaine is more likely to cause diaphragmatic paralysis.