Is Perioperative Fluid and Salt Balance a Contributing Factor in Postoperative Worsening of Obstructive Sleep Apnea?

Abstract

An understanding of the potential mechanisms underlying recurrent upper airway collapse may help anesthesiologists better manage patients in the postoperative period. There is convincing evidence in the sleep medicine literature to suggest that a positive fluid and salt balance can worsen upper airway collapse in patients with obstructive sleep apnea through the redistribution of fluid from the legs into the neck and upper airway while supine, in a process known as "rostral fluid shift." According to this theory, during the day the volume from a fluid bolus or from fluid overload states (i.e., heart failure and chronic kidney disease) accumulates in the legs due to gravity, and when a person lies supine at night, the fluid shifts rostrally to the neck, also owing to gravity. The fluid in the neck can increase the extraluminal pressure around the upper airways, causing the upper airways to narrow and predisposing to upper airway collapse. Similarly, surgical patients also incur large fluid and salt balance shifts, and when recovered supine, this may promote fluid redistribution to the neck and upper airways. In this commentary, we summarize the sleep medicine literature on the impact of fluid and salt balance on obstructive sleep apnea severity and discuss the potential anesthetic implications of excessive fluid and salt volume on worsening sleep apnea.

Society of Anesthesia and Sleep Medicine Guidelines on Preoperative Screening and Assessment of Adult Patients With Obstructive Sleep Apnea

“… 31 , 169 We recommend the continued use of PAP therapy at previously prescribed settings during periods of sleep while hospitalized. Adjustments may need to be made to the settings to account for perioperative changes, such as facial swelling, upper airway edema, fluid shifts, 170 – 172 pharmacotherapy, and respiratory function. It should be noted that PAP therapy is not an alternative to appropriate monitoring.…”

Surgical management of obstructive sleep apnoea: A position statement of the Australasian Sleep Association*

“…31 The combination of excessive intravenous fluid and rostral fluid shifts from immobilization, supine positioning and compression stockings can exacerbate post-operative OSA. 32…”

“…Significant increase in both neck circumference and post‐operative AHI has been demonstrated in males aged ≥40 years with infusion of normal saline (0.9% NaCl) 31 . The combination of excessive intravenous fluid and rostral fluid shifts from immobilization, supine positioning and compression stockings can exacerbate post‐operative OSA 32 …”

Understanding Phenotypes of Obstructive Sleep Apnea: Applications in Anesthesia, Surgery, and Perioperative Medicine

“…Additionally, overnight rostral fluid shift from the legs to the neck may narrow the pharyngeal lumen in some patients with edema because of excess extracellular fluid volume. 14 …”