HEMOGLOBIN-HAMMERSMITH PRECLUDES MONITORING WITH CONVENTIONAL PULSE OXIMETRY

We report a case of a 15-yr-old North American Indian female with haem oglobin Hammersmith, scheduled for elective tonsillectomy, whose arter ial oxygen saturation could not be reliably monitored perioperatively because of technical limitations of conventional dual wavelength pulse oximetry. The patient was chronically icteric. She had an atrial sept al defect with a small L --> R shunt demonstrated by echocardiography. On arrival in the operating room pulse oximetry (Nellcor-Model N100) demonstrated a saturation of 45% whilst breathing room air. Her oxygen saturation increased to 60% whilst breathing 100% oxygen via a face m ask. An arterial blood gas performed whilst breathing 100% oxygen reve aled a PaO2 of 418 mmHg. Tonsillectomy was completed uneventfully unde r general anaesthesia. The pulse oximeter did not provide any clinical ly useful information throughout the case. In conclusion, conventional dual wavelength pulse oximeters cannot give an accurate estimate of o xygenation in patients with haemoglobin Hammersmith. Assessment of oxy genation in these patients requires alternative monitoring techniques.