Influence of Ventilation Strategies and Anesthetic Techniques on Regional Cerebral Oximetry in the Beach Chair Position

Abstract

Background Beach chair positioning during general anesthesia is associated with cerebral oxygen desaturation. Changes in cerebral oxygenation resulting from the interaction of inspired oxygen fraction, end-tidal carbon dioxide and anesthetic choice have not been fully evaluated in anesthetized patients in the beach chair position. Methods This was a prospective interventional within-group study of patients undergoing shoulder surgery in the beach chair position that incorporated a randomized comparison between two anesthetics. Fifty-six patients were randomized to receive desflurane or total intravenous anesthesia with propofol. Following induction of anesthesia and positioning, inspired oxygen fraction (Fio2) and minute ventilation were sequentially adjusted for all patients. Regional cerebral oxygenation (rSO2) was the primary outcome and was recorded at each of five set points. Results While maintaining Fio2 at 0.3 and end tidal carbon dioxide (PETCO2) at 30mmHg there was a decrease in rSO2 from 68%, SD 12 to 61%, SD 12 (p<0.001) following beach chair positioning. The combined interventions of increasing Fio2 to 1.0 and increasing Petco2 to 45mmHg resulted in a 14% point improvement in rSO2 to 75%, SD 12 (p <0.001) for patients anesthetized in the beach chair position. There was no significant interaction effect of the anesthetic at the study intervention points. Conclusions Increasing Fio2 and Petco2 resulted in a significant increase in rSO2 that overcomes desaturation in patients anesthetized in the beach chair position and that appears independent of anesthetic choice.

Modelling of the Effect of End‐Tidal Carbon Dioxide on Cerebral Oxygen Saturation in Beach Chair Position under General Anaesthesia

“…Among these factors, PaO 2 , metabolic demand and haemoglobin were not considered in our model because PaO 2 and haemoglobin were maintained at similar values during data collection, and change in metabolic demand might be insignificant during general anaesthesia. There was a linear relationship between rSO 2 and EtCO 2 in our results, which suggests that increasing EtCO 2 by ventilation adjustment may be the most convenient and effective method for decreasing cerebral desaturation and related complications, which is consistent with previous results [4,9].…”

“…Further hypotension induced for better visualization of the surgical field might aggravate cerebral desaturation [4,5]. As cerebral desaturation during surgery is associated with postoperative cognitive dysfunction and stroke [6,7], prevention and treatment of cerebral desaturation is necessary.As cerebral oxygenation is dependent on cerebral perfusion and oxygen transport, interventions for the prevention and treatment of cerebral desaturation during shoulder surgery include increasing systemic arterial pressure with vasopressors, increasing end-tidal carbon dioxide (EtCO 2 ) with ventilation adjustment and increasing fraction of inspired oxygen (FiO 2 ) [3,4,8,9]. Although increases in systemic arterial pressure may cause rapid increases in cerebral blood flow (CBF), CBF returns to its baseline value within a few seconds by the mechanism of cerebral autoregulation, which aims to maintain a stable CBF over a wide range of mean arterial pressures (MAP) of 70-150 mmHg [10][11][12].…”

Cerebral and Cardiovascular Effects of Analgesic Doses of Ketamine During a Target Controlled General Anesthesia-a Prospective Randomized Study

“…Consequently, coadministration of analgesic doses of ketamine and propofol could have opposite effects on rSO 2 and because of that our results only show a small variation of rSO 2 values. Additionally, it has also been published, recently, that the increase of inspired oxygen fraction and end-tidal CO 2 resulted in a significant increase in rSO 2 in patients anesthetized in the beach chair position and that appeared to be independent of anaesthetic choice (desflurane or total intravenous anaesthesia with propofol) [24]. There are potential limitations associated to our study.…”

Daring discourse: is nerve block with sedation the safest anesthetic for beach chair position?

“…In a study which compared ventilation strategies and anesthetic techniques among patients in BCP for shoulder surgery, Picton et al randomized fifty-six patients to receive maintenance anesthesia with either desflurane or an intravenous technique with propofol 49. The inspired oxygen concentration was elevated from 0.3 to 1.0 with a controlled ETCO2 level at 30 mm Hg.…”