Chronic Angiotensin Converting Enzyme Inhibitors in Intermediate Risk Surgery

Primary research hypothesis: Patients who continue their chronic ACEI therapy up to and including the morning of a non-cardiac, non-vascular surgery will experience more intraoperative hypotension than those who transiently hold their chronic ACEI preoperatively.

Secondary research hypothesis #1: Patients who continue their chronic ACEI up to and including the morning of a non-cardiac, non-vascular surgery will experience better postoperative control of hypertension than those who transiently hold their chronic ACEI preoperatively.

Secondary research hypothesis #2: Patients who continue their chronic ACEI up to and including the morning of a non-cardiac, non-vascular surgery will experience less acute renal failure than those who transiently hold their chronic ACEI preoperatively.

Secondary research hypothesis #3: In the subgroup of patients with a preoperative systolic blood pressure less than 110 mmHg, those who continue their chronic ACEI therapy up to and including the morning of a non-cardiac, non-vascular surgery will experience more intraoperative hypotension than those who transiently hold their chronic ACEI preoperatively.

Secondary research hypothesis #4: In the subgroup of patients above the age of 64, those who continue their chronic ACEI therapy up to and including the morning of a non-cardiac, non-vascular surgery will experience more intraoperative hypotension than those who transiently hold their chronic ACEI preoperatively.

The purpose of this study is to determine if transient discontinuation of angiotensin converting enzyme inhibitors (ACEIs) is necessary prior to non-cardiac, non-vascular surgery. ACEIs have been associated with intraoperative hypotension during vascular and cardiac surgeries. Patients presenting to the University of Nebraska Medical Center Pre-Anesthesia Screening (PAS) Clinic who are on chronic ACEI therapy will be eligible for enrollment. Subjects will be randomized to either omit or continue their ACEI preoperatively. The outcome of interest is intraoperative hypotension defined as a systolic blood pressure less than 80 mmHg. Blood pressure will be followed not only throughout surgery, but also during recovery and the remainder of hospitalization. Renal function will be assessed with creatinine measurements in the PAS clinic and on the first postoperative day. No follow-up is planned beyond discharge from the hospital.

Eligibility Criteria:
Inclusion Criteria:

* Referred to the University of Nebraska Medical Center Pre-Anesthesia Screening Clinic for preoperative evaluation.
* Above referral must be in anticipation of a non-cardiac, non-vascular surgery.
* Must have been on ACE-Inhibitor therapy for at least six weeks.

Exclusion Criteria:

* Hypotension (systolic blood pressure \< 90 or diastolic blood pressure \<60) at the time of preoperative evaluation
* Uncontrolled Hypertension (systolic blood pressure \> 150 or diastolic blood pressure \> 95) at the time of preoperative evaluation
* Surgery during which vasopressor use is anticipated (carotid endarterectomy, major abdominal operations, orthopedic oncology)
* Surgery for pathology related to vasoactive substances (carcinoid, pheochromocytoma)
* Left Ventricular ejection fraction less than 40%
* Clinical evidence of decompensated heart failure at the time of preoperative evaluation
* End-stage renal disease
* Organ transplant surgeries