Phrenic Nerve Block and Respiratory Effort in Pigs and Critically Ill Patients with Acute Lung Injury. (29th March 2022)

• Record Type: Journal Article
• Authors: Pereira, Sérgio M.; Sinedino, Bruno E.; Costa, Eduardo L. V.; Morais, Caio C. A.; Sklar, Michael C.; Adkson Sales Lima, Cristhiano; Nakamura, Maria A. M.; Ranzani, Otavio T.; Goligher, Ewan C.; Tucci, Mauro R.; Ho, Yeh-Li; Taniguchi, Leandro U.; Vieira, Joaquim E.; Brochard, Laurent; Amato, Marcelo B. P.
• Is Part Of: Anesthesiology. Volume 136:Number 5(2022)
• Page Start: 763
• Page End: 778
• Publication Date: 2022-03-29
• Subjects: Anesthesiology -- Periodicals; Anesthetics -- Periodicals; Anesthesia -- Periodicals; 617.9605
• DOI: 10.1097/ALN.0000000000004161
• Languages: English
• ISSNs: 0003-3022

Abstract

Abstract : Background: Strong spontaneous inspiratory efforts can be difficult to control and prohibit protective mechanical ventilation. Instead of using deep sedation and neuromuscular blockade, the authors hypothesized that perineural administration of lidocaine around the phrenic nerve would reduce tidal volume (VT ) and peak transpulmonary pressure in spontaneously breathing patients with acute respiratory distress syndrome. Methods: An established animal model of acute respiratory distress syndrome with six female pigs was used in a proof-of-concept study. The authors then evaluated this technique in nine mechanically ventilated patients under pressure support exhibiting driving pressure greater than 15 cm H2 O or VT greater than 10 ml/kg of predicted body weight. Esophageal and transpulmonary pressures, electrical activity of the diaphragm, and electrical impedance tomography were measured in pigs and patients. Ultrasound imaging and a nerve stimulator were used to identify the phrenic nerve, and perineural lidocaine was administered sequentially around the left and right phrenic nerves. Results: Results are presented as median [interquartile range, 25th to 75th percentiles]. In pigs, VT decreased from 7.4 ml/kg [7.2 to 8.4] to 5.9 ml/kg [5.5 to 6.6] ( P < 0.001), as did peak transpulmonary pressure (25.8 cm H2 O [20.2 to 27.2] to 17.7 cm H2 O [13.8 to 18.8]; P < 0.001) and driving pressure (28.7 cm H2 O [20.4 to 30.8] to 19.4 cm H2 O [15.2 to 22.9]; P < 0.001). Ventilation in the most dependent part decreased from 29.3% [26.4 to 29.5] to 20.1% [15.3 to 20.8] ( P < 0.001). In patients, VT decreased (8.2 ml/ kg [7.9 to 11.1] to 6.0 ml/ kg [5.7 to 6.7]; P < 0.001), as did driving pressure (24.7 cm H2 O [20.4 to 34.5] to 18.4 cm H2 O [16.8 to 20.7]; P < 0.001). Esophageal pressure, peak transpulmonary pressure, and electrical activity of the diaphragm also decreased. Dependent ventilation only slightly decreased from 11.5% [8.5 to 12.6] to 7.9% [5.3 to 8.6] ( P = 0.005). Respiratory rate did not vary. Variables recovered 1 to 12.7 h [6.7 to 13.7] after phrenic nerve block. Conclusions: Phrenic nerve block is feasible, lasts around 12 h, and reduces VT and driving pressure without changing respiratory rate in patients under assisted ventilation. Abstract : The authors evaluated the effects of phrenic nerve block in a porcine model of acute respiratory distress syndrome and in nine patients with excessive inspiratory effort with acute respiratory distress syndrome on mechanical ventilation evaluating transdiaphragmatic pressures and electrical activity, as well as distribution of ventilation by electrical impedance tomography. In both groups, tidal volume, driving pressure, peak transpulmonary pressure, and electrical activity of the diaphragm decreased significantly with phrenic nerve block, with a slight decrease in dependent ventilation, while the respiratory rate was unchanged. Duration of the block was approximately 12 h.