PURPOSE: Cardiopulmonary bypass induced vasodilatory hypotension which requires treatment with pressor agents to maintain an adequate perfusion pressure is more frequently seen particulary in light of the increased use of angiotensin-converting enzyme inhibitors. We investigated the incidence and predictors of cardiopulmonary bypass induced vasodilatory hypotension and evaluated the safety and efficacy of using low-dose arginine vasopressin as a treatment option.
METHODS: Consecutive, unselected patients undergoing cardiac operations using cardiopulmonary bypass were studied prospectively (n=152). Patients experiencing vasodilatory hypotension (defined as mean arterial pressure ≤;50 mmHg) during cardiopulmonary were supported with intravenous vasopressin (0.1 Units/minute) as first line therapy. The efficacy and safety of vasopressin at maintaining mean arterial pressures ≥70 mmHg during cardiopulmonary bypass in addition to multivariable predictors of vasodilatory hypotension were analyzed.
RESULTS: Vasodilatory hypotension occurred in 31%(47/152) of patients (mean arterial pressure 40±6 mmHg) during cardiopulmonary bypass. Maintenance of a mean arterial pressure >70 mmHg (mean arterial pressure 83±10 mmHg) during cardiopulmonary bypass was achieved in 96%(45/47) using vasopressin alone (p<0.0001). Vasopressin infusion averaged 6.0±9.4 hours (range 0.08-48 hours). Of the patients who received radial artery grafts, 25%(14/56) experienced vasodilatory hypotension and were effectively managed with vasopressin without evidence spasm, myocardial infarction, or hypoperfusion syndrome. Complications between groups were similiar. Multivariable predictors of vasodilatory hypotension were age >65 (odds ratio 6.5;95% confidence interval 1.5-28.4;p=0.01) and the use of preoperative angiotensin-converting enzyme inhibitors (odds ration 2.9; 95% confidence interval 1.1-7.7;p=0.04).
CONCLUSION: Risk factors for cardiopulmonary induced vasodilatory hypotension include increased age and preoperative use of angiotensin-converting enzyme inhibitors. Arginine vasopressin is an effective and inexpensive ($10 US) treatment for cardiopulmonary bypass induced vasodilatory hypotension.
CLINICAL IMPLICATIONS: Vasodilatory hypotension is frequently encountered during cardiopulmonary bypass. Arginine vasopressin, as an alternative to traditional catecholamine agents, is a safe and effective management option.
DISCLOSURE: Keith Allen, No Financial Disclosure Information; No Product/Research Disclosure Information