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Department of Anaesthesia and Critical Care, Government Medical College and Hospital, Chandigarh, India
To the Editor:
A 39-yr-old female patient with oculocutaneous albinism (OCA) underwent total abdominal hysterectomy. She had been using Babchi (Psoralea corylifolia) herb extract for OCA. BavachininA, a flavanone isolated from its fruits, is an irritant with photosensitizing properties. Preanesthetic evaluation, laboratory investigations, and chest radiograph were normal. Soon after induction of general anesthesia, oxygen saturation (SpO2) gradually decreased from 99% to 85% (Datex Ohmeda, 5250 RGM). Bilateral ventilation of lungs was normal by auscultation. Hemodynamic stability, normothermia, and good pulse signal indicated that the digital probe was correctly positioned on the finger (1). Clinically, the patient appeared well oxygenated. Arterial blood gas analysis showed PaO2104 mm Hg. SpO2, although it improved after reapplication of probe, again decreased, and low SpO2 readings were frequently observed intraoperatively, necessitating repeated change of sensor-test site. The patient did not complain of respiratory discomfort after recovery. Literature review on effects of skin pigmentation on pulse oximetry revealed reports of Spo2 underestimation in dark individuals (2). OCA is an autosomal recessive trait, characterized by tyrosinase deficiency, interrupting melanosomes formation in skin and hair. Its other variants, such as yellow mutant, Hermansky-Pudlak syndrome, and Chedlak-Higashi syndrome, may have hematological abnormalities. Reduced melanin decreases visual acuity and enhances sensitivity to ultraviolet light. This case suggests that perhaps the sensitivity to the two light wavelengths (660 nm, 940 nm) utilized by pulse oximeter is affected in OCA (3).
Herbal remedies may include ingredients exerting chemical effects (4). Can Babchi affect SpO2 estimation?
References:
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