Anesth Analg 2004;98:283-284
© 2004 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000099364.07751.3F
EDITORIALS
Sickle Cell Disease: Dogma, Science, and Clinical Care
Joseph R. Tobin, MD, and
John Butterworth, MD
From the Department of Anesthesiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
Address correspondence to Joseph R. Tobin, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157–1009. Address email to jbutter{at}wfubmc.edu
Sickle cell anemia is a lifelong, dynamic, sometimes debilitating disease. Patients with sickle cell disease often present for surgical management of conditions unrelated or directly attributable to the consequences of the illness. In addition to the usual childhood maladies for which surgical attention is required, children and adults may suffer osteonecrosis, solid organ infarction, pulmonary hypertension, and heart failure. As early as preschool age, these patients are considered immunocompromised secondary to splenic infarction. A small subset of patients with sickle cell disease requires repeated hospitalization and care for multiple associated morbidities.
Most historical recommendations regarding the treatment of sickle cell patients in the perioperative period appear to be prudent and rational, and they are generally accepted by our community with little controversy, except with regard to decisions about exchange transfusion therapy. Recommendations to keep the operative arena warm, the patient well hydrated, well oxygenated, and without systemic acidosis are readily accepted. However, the minimal hemoglobin concentration or maximal percent of sickle hemoglobin consistent with perioperative safety are not so well established. Vichinsky et al. (1) published their findings in a comparative trial of conservative versus aggressive transfusion regimens in the perioperative management of sickle cell disease. They concluded that an aggressive protocol of transfusion did not enhance the safety of the patients in the perioperative period. In both groups, approximately 10% of the patients suffered acute chest syndrome despite a difference of hemoglobin S values of 31% versus 59% between the groups. The only deaths reported were in the aggressive transfusion group, and transfusion-related complications were twice as frequent in the aggressive treatment group.
In this month’s journal, Dr. Al-Ghamdi (2) reports the use of lower extremity tourniquets for bilateral total knee replacements in a patient with sickle cell disease. Many would condemn this practice as promoting ischemia and sickling and as unsafe. However, meticulous preoperative preparation and intraoperative management allowed for the use of tourniquets to optimize the surgical conditions, and the patient suffered no obvious perioperative consequences. Indeed, a previous study involving 15 patients, of whom 12 were homozygous HbSS, also reported no complications when tourniquets were used for limb surgery (3). A more historical study also demonstrated no serious consequences with the use of a tourniquet in sickle cell patients for orthopedic surgery (4).
As the understanding of the pathogenesis of sickle cell disease has improved (5), so also has it come time to reexamine one of our dogmas: that tourniquet use is contraindicated in patients with sickle cell disease (6). It is now recognized that acute deoxygenation may not be consistently linked to sickling, but when these cells are slowly and persistently deoxygenated, the classic sickled shape may result. Also, the acute acidotic environment of the extremity after tourniquet placement may alter endothelium-sickle cell interactions. Acidosis will alter membrane-membrane interactions, promote systemic vasodilation, and alter a host of other biochemical reactions acutely. The balance of these may not promote sickling, as is logically concluded.
Nonetheless, shall we abandon rational prudent teachings with findings from a few small studies? Have we learned the true "safety" of tourniquet use in sickle cell patients? We are not promoting reckless abandon to use tourniquets ad lib. Rather, careful consideration should be made of the risks and benefits for the individual patient. In geographic areas with a limited or potentially contaminated blood supply, any measure of blood conservation might be worth the risk to avoid transfusion therapy. Preoperative medical management to enhance HbF production with hydroxyurea may justify a delay in elective surgery. A delay to confirm appropriate blood availability for transfusion or to accomplish preoperative reduction in percent HbS cells may be another avenue.
Postoperative issues that may be approached by the anesthesiologist include the appropriate use of opioid and non-opioid analgesics. Sickle cell patients may either be tolerant to the effects of opioids or may seek desirable side effects (euphoria) of opioids. Rational use of neuraxial and regional anesthesia should be considered for its opioid sparing and nonrespiratory depressant effects. Should we be more aggressive about alternative classes of analgesics in these patients? Might clonidine (with its attendant vasodilation), ketamine/magnesium, and traditional or novel nonsteroidal analgesics have favorable profiles? Need we be concerned with the potential renal physiologic consequences with the latter class of analgesics in sickle cell patients who may have occult renal insufficiency?
The science of understanding and treating the patient with sickle cell anemia is advancing more quickly than our ability to prepare to assist these patients in the perioperative period with our clinically accumulated recommendations. We certainly know to avoid hypoxia, but what maximal percentage HbS is well tolerated? What minimal hematocrit needs to be obtained perioperatively? What degree of acidosis or alkalosis should be our targets? What are optimal analgesic strategies? If we abolish the neuroendocrine stress response to surgery, will we decrease the risk of acute chest syndrome or other sickling complications? A multitude of other stress-induced biochemical mediators contributing to morbidity may yet be discovered. As the genomics of hemoglobinopathies advances, will we characterize the phenotypes that will tolerate stressors? Conversely, will we genetically define other subpopulations (such as those known to be "morbidity-prone") that should be treated in accordance with classic perioperative recommendations (e.g., hydration, exchange transfusion, neuraxial analgesia, avoidance of hypoxia)?
Let us take the opportunity to reassess our dogma, its "obvious" nature, and the lack of supporting evidence for these "best practices." Sometimes new data force old teachings to be readdressed. Al-Ghamdi’s report may spark an interest in re-examining what we know and what we don’t know regarding the risks of current perioperative practices in the patient with sickle cell disease.
References
- Vichinsky EP, Haberkern CM, Neumayr L, et al. A comparison of conservative and aggressive transfusion regimens in the perioperative management of sickle cell disease. N Engl J Med 1995; 333: 206–13.[Abstract/Free Full Text]
- Al-Ghamdi AA. Bilateral total knee replacement under tourniquet in a homozygous sickle cell patient. Anesth Analg 2003; 98: 543–4.
- Adu-Gyamfi Y, Sankarankutty M, Marwa S. Use of a tourniquet in patients with sickle-cell disease. Can J Anaesth 1993; 40: 24–7.[Web of Science][Medline]
- Stein RE, Urbaniak J. Use of the tourniquet during surgery in patients with sickle cell hemoglobinopathies. Clin Orthop 1980; 151: 231–3.
- Bunn HF. Pathogenesis and treatment of sickle cell disease. N Engl J Med 1997; 337: 762–9.[Free Full Text]
- Roizen MF. Anesthetic implications of concurrent diseases. In: Miller RD, ed. Anesthesia. 5th ed. Philadelphia: Churchill Livingstone, 2000: 986.
Accepted for publication September 17, 2003.
This article has been cited by other articles:
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J. M. Sarjeant, J. L. Callum, and A. A. Al-Ghamdi
The Use of Tourniquets in Patients with Sickle Cell Disease * Response
Anesth. Analg.,
August 1, 2004;
99(2):
630 - 630.
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