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Correspondence |
Toronto, Ontario
To the Editor:
Subcutaneous injection (tumescence) of burn wounds and skin graft donor sites with epinephrine-saline solution (1:500 000, 2 µg•mL–1) in conjunction with topical epinephrine dressings (1:33 33, 30 µg•mL–1) reduces blood loss during tangential burn wound excision.1 Despite the demonstration of elevated levels in the blood, the cardiovascular effects of administered epinephrine during anesthesia have not been quantitatively described in the anesthesia literature.2,3 In this pilot study, we performed a semi-quantitative analysis of the incidence and severity of intraoperative cardiovascular adverse events to generate hypotheses and to guide a prospective study of anesthesia for this operation.
A retrospective cohort analysis of all anesthetic and surgical records of 52 consecutive patients (80 operations) admitted to the Ross Tilley Burn Centre between December 30, 1998 and June 30, 1999 was performed. Systolic blood pressure (SBP), heart rate (HR), and electrocardiogram data were collected in the 15 min (baseline) period prior to epinephrine injection and for five-minute intervals over a period of 60 min postepinephrine administration.
The mean age of the study cohort was 46 yr (95% CI, 42–49), and the mean % total body surface area burn was 19% (95% CI, 16–22). The majority of the patients were male (69%). The most frequent (mode) ASA physical status classification was II. In the 80 operations the mean dose of subcutaneous epinephrine injected was 5.6 mg (95% CI, 3.3–6.8). In 62 of 80 cases there was an increase in SBP of less than 15% from the pre-injection baseline. In 18 of 80 cases an increase in SBP of greater than 15% occurred (mean 45.3%, 95% CI, 35.0–55.6). Correlation between epinephrine dose, whether subcutaneous (Pearson correlation coefficient r2 = 0.003) or topical (r2 = 0.010) and % change in SBP was poor (Figure). In 6/18 cases with an increase in SBP of greater than 15% there was also a mean increase in HR of 11 beats•min–1 (95% CI, 3–20). Transient ST segment depression occurred in 1/18 patients. There were no intraoperative dysrhythmias.
To summarize our findings, administration of subcutaneous and topical epinephrine during burn surgery was associated with a low incidence of intraoperative cardiovascular sequelae. There was a poor correlation between dose of epinephrine and intraoperative changes in blood pressure. Our results may reflect desensitized beta-receptor responses following burn injury, which have been demonstrated in rats4 and in human ex vivo lymphocytes.2 Alternatively, they may reflect varying depths of anesthesia in the study cohort. A prospective study will investigate the interaction between depth of anesthesia and cardiovascular responses during burn surgery.
References
1 Cartotto R, Musgrave MA, Beveridge M, Fish J, Gomez M. Minimizing blood loss in burn surgery. J Trauma 2000; 49: 1034–9.[Medline]
2 McQuitty CK, Berman J, Cortiella J, Herndon D, Mathru M. Beta-adrenergic desensitization after burn excision not affected by the use of epinephrine to limit blood loss. Anesthesiology 2000; 93: 351–8.[Medline]
3 Snelling CF, Shaw K. The effect of topical epinephrine hydrochloride in saline on blood loss following tangential excision of burn wounds. Plast Reconstr Surg 1983; 72: 830–6.[Medline]
4 Wang C, Martyn JA. Burn injury alters beta-adrenergic receptor and second messenger function in rat ventricular muscle. Crit Care Med 1996; 24: 118–24.[Medline]
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