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Department of Anesthesia, University of Toronto, Toronto, Canada Director of Transfusion Medicine, Sunnybrook and Women’s College Health Science Centre, Toronto, Canada
To the Editor:
We were interested to read a case report of successful tourniquet use in a sickle cell patient (Hb SS) undergoing knee replacement (1). A case series of 12 Hb SS patients from the same institution in Saudi Arabia also demonstrated use of tourniquets without complication (2). In interpreting these results, it is important to note that Saudi Arabian patients have the Arab-Indian Hb SS haplotype, characterized by more benign disease, attributed to a higher percentage of fetal hemoglobin in their circulation (an average of 25% versus 5–10% in African haplotypes) (3). A case series from Africa, in contrast to the Saudi Arabian experience, reported that 3 of 14 Hb SS patients developed sickle cell related complications after surgery with tourniquet use (4). Given that 83–100% of Hb SS patients in the United States are African haplotypes (6), tourniquet use may not be appropriate for most sickle cell patients in North America.
Also in this report (1), the patient underwent preoperative exchange transfusion reducing Hb S from 82.6% to 47%. However, a RCT demonstrated that simple preoperative transfusion (total Hb to 10 g/dL) was as effective as exchange transfusion (Hb S <30% of total) in preventing perioperative complications in Hb SS patients, and was also associated with a 50% reduction in transfusion-related complications (5). Thus, preoperative exchange transfusion is rarely indicated.
References
Chairman of Anesthesia Department, King Faisal University, Dammam, Saudi Arabia
In Response:
The letter by Sarjeant and Callum discusses two important controversial issues in the perioperative management of patients with sickle cell disease, namely, the use of tourniquets and preoperative blood transfusion.
I agree with Drs. Sarjeant and Callum that Arab-Indian sickle cell disease is a more benign one than the African form, probably because of the more frequent percentage of HbF. The case reported, however, cannot be regarded as a benign one, since the patient was rendered crippled by the age of 27 years (1). Moreover, we think that with adequate preoperative preparation and with advances in intraoperative monitoring and homeostasis, tourniquet use may be considered if it is beneficial to the patient.
A recent Cochrane-based study (2) concluded that, while, in general, conservative transfusion appears to be as effective as aggressive transfusion in preparation for surgery in sickle cell patients, further research is needed to examine the optimal regime for different surgical types, and to address whether preoperative transfusion is needed in all surgical situations. Exchange transfusion for such a patient was an essential part of his preoperative preparation. As our patient was scheduled for bilateral total knee replacement under tourniquet, it was felt that a more tight control of HbS through exchange transfusion would contribute to better outcome.
We believe that in areas of medicine where large series RCT is difficult to perform or unethical, breakthrough cases, dictated by the patient’s benefit and careful discussions, as with the editorial of Drs. Tobin and Butterworth (3) and the current letter, form the basis of changing traditional practice.
References
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