Haemoglobin Hammersmith precludes monitoring with conventional pulse oximetry.

We report a case of a 15-yr-old North American Indian female with haemoglobin Hammersmith, scheduled for elective tonsillectomy, whose arterial 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 septal 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 mask. An arterial blood gas performed whilst breathing 100% oxygen revealed a PaO2 of 418 mmHg. Tonsillectomy was completed uneventfully under general anaesthesia. The pulse oximeter did not provide any clinically useful information throughout the case. In conclusion, conventional dual wavelength pulse oximeters cannot give an accurate estimate of oxygenation in patients with haemoglobin Hammersmith. Assessment of oxygenation in these patients requires alternative monitoring techniques.