Arterial Stiffness and General Anesthesia Induced Hypotension in Patients on Angiotensin-converting Enzyme Inhibitors

Completed

Conditions studied: Hypotension, Arterial Stiffness

In brief

Induction of general anesthesia to the patient could be a challenging period of anesthesia management. Due to autonomic system suppression, hemodynamic fluctuation, such as hypotension or hypertension, is commonly seen during this period. Furthermore, it has been observed that a fraction of patients who develop hypotension may be refractory to vasoactive medications to attempt to restore the systemic arterial blood pressure back to an acceptable level. Previous studies have shown that patients chronically taking angiotensin converting enzyme (ACE) inhibitors have a higher incidence of developing hypotension under general anesthesia as well as being refractory to adrenergic vasoconstrictor medications given to help restore systemic blood pressure. Interestingly, not all patients taking ACE inhibitors have shown the described hemodynamic response after induction of general anesthesia. Therefore, investigators are attempting to identify what changes in vascular physiology in those patients may contribute to acute refractory systemic hypotension. Specifically, investigators wish to explore whether differences in baseline levels of arterial stiffness potentially contribute to this phenomenon. Arterial applanation tonometry is a non-invasive technique that has been shown to reliably provide indices of arterial stiffness. In the proposed project, applanation tonometry will be performed on the right carotid and femoral arteries to assess carotid-femoral pulse wave velocity, a surrogate for aortic stiffness. (SphygmoCor system, AtCor Medical, Sydney, Australia) The measurement will be obtained before induction of general anesthesia in the pre-surgical area. During induction of general anesthesia with standard induction agents, brachial blood pressure will be measured by a cuff every minute up to 10 minutes after tracheal intubation. A hypotensive response to anesthesia will be defined by a systolic arterial blood pressure below 90mmHg upon induction. Hypotensive patients that do not respond to vasoconstrictor medications (i.e. requires more than 200 mcg phenylephrine to maintain systolic arterial blood pressure above 90 mmHg) will be classified as 'refractory hypotensive." Using non-invasive applanation tonometry, we will be able to examine if aortic stiffness has a propensity to become refractory hypotension after induction of general anesthesia. This information will potentially help identify future patients that might be at greater risk of developing refractory hypotension in response to induction of general anesthesia.

Key facts

Study ID

NCT02416024

Run by

University of Iowa

People needed

72

Starts

2013-08-01

Expected to finish

2018-09-01

Last updated by the study team

2019-03-18

Who can join

Age: 50 and older, up to 85. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• There will be three study populations. The first study population will include 60 adult patients over 50 years old and on ACE inhibitors for more than 3 months, scheduled for surgery under general anesthesia in the second case in the Main Operating Room at the UIHC. Patients who are taking angiotensin receptor inhibitors will not be enrolled for the study.
• The second study population will include 20 adult patients over 50 years old who are not taking an ACE inhibitor and are currently taking a beta blocker, a calcium channel blocker, or a diuretic for more than 3 months, scheduled for surgery under general anesthesia in the Main Operating Room at the UIHC.

You may not qualify if…

• We will exclude patients with diabetes (on insulin therapy), renal insufficiency (Cr>2.0), history of arterial bypass (i.e. F-F bypass), history of carotid endoarterectomy, angiotensin receptor inhibitor medication, heart rate <40 bpm or >100 bpm, atrial fibrillation/flutter, history of ischemic stroke, transient ischemic attack, myocardial infarction or coronary revascularization (any type) within 6 months, known left main or 3-vessel coronary disease positive myocardial perfusion study without subsequent revascularization, angina or heart failure (>3 NYHA) class 3, known left ventricle ejection fraction <30%, pulmonary hypertension (PA systolic >50mmHg), right ventricle dysfunction, or a preoperative systolic blood pressure of >180 mmHg or <110 mmHg within 1 month prior to surgery.

Where it is running

• University of Iowa Hospitals and Clinics — Iowa City, Iowa, United States

Full record on ClinicalTrials.gov

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