Risk Factors for Perioperative Hypotension After Abdominal Aortic Aneurysm Repair and Its Impact on Early Survival

Background: An abdominal aortic aneurysm (AAA) is a localized dilatation of the infrarenal aorta that, when it meets critical criteria, can rupture and cause a vital emergency, requiring immediate surgery with a mortality rate close to 85%(1). Also, symptomatic AAA and/or imminent rupture is a surgical emergency that should be recognized and treated promptly. Elective procedures are usually performed in patients with AAA with a diameter greater than 5.5 cm in men and 5.0 cm in women(2,3).

There are different techniques for the surgical repair of AAA, which are divided into two main groups: endovascular and open procedures. The endovascular procedure offers an early survival benefit, better postoperative recovery, and fewer incision-related complications as it is a minimally invasive procedure. However, it requires more re-interventions, but most are mainly minor endovascular procedures. In contrast, an open approach has a better 15-year late survival benefit, associated with greater graft durability, a lower rate of re-interventions, and the additional advantage of being more affordable (4-7).

Several risk factors have been established around surgical procedures that may affect the outcome, including preoperative and intraoperative hypotension. Preoperative hypotension is one of the most crucial factors, especially when talking about ruptured AAA, where it is present with a high frequency and has been seen as an association with mortality with an AOR of 3.28 (CI 1.75-5.41; P < .001) (8). For intraoperative hypotension, a study showed that it increased the 30-day mortality after an elective open repair of AAA with an OR of 6.61 (CI 0.71-61.07; p = 0.05). Also, it has been associated with liver dysfunction (p < 0.001) and colonic ischemia (P=0.021) (9-11).

However, the frequency and effects of postoperative hypotension in open and endovascular AAA surgery have not been described in the literature despite the everyday use of vasopressor medications (48%) in the immediate medical management following an open AAA repair(12). However, other studies have shown that postoperative hypotension in abdominal surgery is a significant complication that can have adverse effects on the patient. This condition is characterized by a decrease in blood pressure, which can lead to myocardial injury, acute kidney damage, and an increase in short-term mortality(13).

According to literature, postoperative hypotension is common after major abdominal surgeries, and its detection may be suboptimal if routine vital sign assessments are the sole monitoring method. A prospective observational study found that nearly one-quarter of patients experienced episodes of mean arterial pressure (MAP) below 70 mmHg for at least 30 minutes, many of which went undetected through routine evaluations(14). Another study highlighted that prolonged postoperative hypotension, defined by absolute MAP thresholds, is associated with myocardial injury, especially when MAP falls below 65 mmHg for extended periods (15).

In addition, in other vascular interventions like carotid endarterectomy, postoperative hypotension has been associated with increased risks of 30-day mortality, stroke, myocardial infarction, and length of stay(16).

Given the potential implications for adverse perioperative outcomes, it is essential to elucidate potential risk factors to tailor the perioperative management of AAA repair further. Thus, we aim to describe the mortality and determine the risk factors associated with peroperative and postoperative hypotension at 48 hours in patients who underwent an Infrarenal Abdominal Aortic Aneurysm Repair at the Rijnstate Hospital during the period 1-1-2013 until 31-12-2021.

Research question: What were the risk factors associated with postoperative hypotension in patients who underwent an Infrarenal Abdominal Aortic Aneurysm Repair at the Rijnstate Hospital during the period 2013 to 2021?

Hypothesis:

Alternate hypothesis: There are specific risk factors associated with postoperative hypotension in patients who underwent an Infrarenal Abdominal Aortic Aneurysm Repair at the Rijnstate Hospital during the period 2013 until 2021.