Adequate blood flow across a microvascular anastomosis is a critical factor in maintaining vessel patency and delivering a successful outcome in free flap surgery. Blood pressure is often used as a marker of blood flow intraoperatively because of its relationship with cardiac output (cardiac output = mean arterial pressure/systemic vascular resistance). Anesthetists use several different strategies to increase blood pressure at critical times, such as on completion of an anastomosis or dissection of a vascular pedicle. These include anesthetic modulation, fluid boluses, and sympathomimetics such as ephedrine. Maintaining correct fluid balance intraoperatively is essential; intravenous fluids increase cardiac output but fluid boluses can have an unpredictable effect on blood pressure and may result in undesirable fluid shifts. Intravenous ephedrine may actually decrease cardiac output by increasing systemic vascular resistance.
Cyclizine is an H1-receptor antagonist (antihistamine) that is used primarily as an antiemetic, but in our experience, it is effective at providing a controlled rise in arterial pressure intraoperatively. To illustrate this benefit, we conducted a small prospective study.
Heart rate and arterial blood pressure were assessed in five patients (four men and one woman; mean age, 56 years) undergoing soft-tissue reconstruction. Observations were recorded at 5-minute intervals over a 40-minute period, during which 25 mg of intravenous cyclizine was administered at 10 minutes. Statistical analysis was performed using a paired t test. A value of p < 0.05 was considered statistically significant.
The results are illustrated in Figure 1. Administration of intravenous cyclizine resulted in a mean increase in systolic blood pressure of 9.4 ± 5.4 mmHg at 5 minutes (p = 0.012) over resting pressure, increasing to 18.2 ± 3.5 mmHg at 10 minutes. A significant difference was maintained to 30 minutes after injection. This was mirrored by a significant increase in heart rate (8 ± 5.3 at 5 minutes; p = 0.001), suggesting that cyclizine was mediating changes in blood pressure through a positive chronotropic action. In addition to its favorable physiologic effects, cyclizine benefits from a benign therapeutic profile, although it should be avoided in patients with severe heart failure.1
Intravenous cyclizine is a safe and effective method of delivering a boost in blood pressure when administered intraoperatively. Although no substitute for judicious fluid management, it is a useful tool for increasing blood flow at critical times during free tissue transfer without the need for sudden volume shifts or vasopressive stimulants.
William A. Townley, M.R.C.S.
Ian C. Wright, F.R.C.A.
Ian Whitworth, F.R.C.S.(Plast.)
Odstock Center for Burns, Plastic and Reconstructive Surgery
Salisbury District Hospital
Salisbury, United Kingdom
There was no financial support for this work, no associated pecuniary or financial interest, and no conflict of interest.
1.Tan LB, Bryant S, Murray RG. Detrimental haemodynamic effects of cyclizine in heart failure. Lancet
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