Baroreflex impairment and morbidity after major surgery

Area of Science:

• Cardiovascular Physiology
• Surgical Outcomes Research
• Autonomic Nervous System Function

Background:

• Baroreflex dysfunction is prevalent in cardiometabolic diseases and linked to critical illness.
• Laboratory models demonstrate baroreflex dysfunction impairs cardiac contractility and cardiovascular performance.
• This dysfunction increases morbidity risk following trauma and sepsis.

Purpose of the Study:

• To investigate the hypothesis that baroreflex dysfunction contributes to excess postoperative morbidity after major surgery.
• To examine the association between baroreflex dysfunction and inadequate perioperative tissue oxygen delivery.
• To assess the impact of baroreflex dysfunction on early postoperative morbidity and cardiovascular performance.

Main Methods:

• A randomized controlled trial of goal-directed haemodynamic therapy (GDT) in higher-risk surgical patients.
• Spontaneous baroreflex sensitivity (BRS) assessed using a validated sequence method via arterial line pre-surgery.
• BRS calculated during 6-hour postoperative GDT; analyses performed by blinded investigators.

Main Results:

• Postoperative baroreflex dysfunction (BRS <6 mm Hg s(-1)) was associated with increased infectious (RR 1.75) and cardiovascular morbidity (RR 2.39).
• Patients with baroreflex dysfunction had a higher likelihood of prolonged hospital stay (HR 1.62).
• Oxygen delivery was significantly lower (36%) in patients with baroreflex dysfunction not receiving GDT.

Conclusions:

• Baroreflex dysfunction is significantly associated with excess postoperative morbidity and impaired cardiovascular performance.
• Delayed hospital discharge is more likely in patients exhibiting baroreflex dysfunction.
• Autonomic dysfunction plays a mechanistic role in determining perioperative outcomes.