Effect of Two Regimens of Fluid Administration on Airway Edema in Prone-Position Surgery

Surgeries in prone position expose a patient to multitude of complications including laryngeal edema which may be related to the volume of fluid administered. Administering larger volumes of fluid intraoperatively may contribute to significant tissue edema, leading many anesthesiologists to practice a restrictive fluid infusion strategy. Although previous studies have compared fluid infusion strategies, changes in airway dimensions leading to airway edema have not been extensively investigated. Here, we compared two fluid infusion regimens in patients undergoing spine surgery in the prone position, and assessed their association with airway edema by means of the cuff leak test (CLT).

The aim of this study was to test the hypothesis whether a larger volume of crystalloid administration in spine surgeries performed in prone position would result in greater chances of airway edema, than would a restricted infusion policy, utilizing the CLT.

After ethical committee approval, thirty patients, aged 21-60 years, American Society of Anesthesiologists Status I or II, scheduled for elective spine surgery in the prone position, were selected. Group 1 (restrictive group) received 3 mL.kg ^{- 1}.h ^{- 1}, whereas Group 2 (permissive group) received 5 mL.kg ^{- 1}.h ^{- 1} of crystalloids plus urine output replacement. The airway edema was assessed by CLT which was performed soon after intubation (T1) and before extubation (T2). Cuff leak volume (CLV) was calculated from the difference in tidal volumes before (VT _i) and after cuff deflation (VT _e). Airway edema was evaluated by calculating the differences in the CLV at T1 and T2 (ΔCLV); the more the value of Δ CLV which means greater difference between these two points, the more the decrease in laryngeal lumen, signifying an increased risk of airway edema.

Decrease in laryngeal lumen was observed in patients who received permissive fluid regimen than that of the restrictive group, signifying more chances of airway edema in the former group. In addition, a poor correlation was found between the duration of anesthesia and development of airway edema in our study group.

Because surgeries in the prone position are at risk of airway edema, restrictive fluid regimen strategy should be preferred over the liberal one as there are more chances of reduction in laryngeal lumen dimensions with permissive fluid infusions.