To the Editor:
Pulse oximetry is an important method of monitoring during anesthetic and intensive care management. There are very few complications associated with it. Recently we had a patient complaining of numbness over the distal phalanx of his right middle finger, where he had the pulse oximeter probe.
A 60-yr-old man underwent coronary artery bypass graft surgery (CABG) without complications. Ulnar nerve conduction studies were performed at the time of induction as part of an ongoing study currently underway at our institution. As part of the followup for this study, the patient was examined on the first postoperative day, where ulnar nerve conductions were found to be normal. However, the patient complained of numbness, and on examination he had decreased pain and temperature sensation in his right middle finger localized to the terminal phalanx, which was the site of his pulse oximeter probe intraoperatively. The distribution was circumferential in nature, extending from the distal interphalangeal joint to the end of the digit. Motor function was completely normal. Past medical history was significant for coronary artery disease, hypertension, and peptic ulcer disease, with no documented peripheral neuropathy preoperatively. Examination by a neurologist and an anesthesiologist did not reveal any other neurologic deficit.
This numbness of the distal phalanx of a finger with the use of pulse oximetry has not been reported. The probe, if improperly positioned, can compress the digital vessels and nerves and produce damage. We use two types of probes, the Nellcor probe (Nellcor Inc., Hayward, CA), which does not enclose the finger completely and is cushioned, and the Ohmeda probe (Louisville, CO), which encloses the finger and is not cushioned. The size of the probe to the size of the finger is important, and the pressure exerted is greater with a smaller probe on a large finger. The probes produce ischemic injuries of the skin of the digits and the pinna of the ear, and they burn if applied improperly and for prolonged periods [1-4]. We used the Ohmeda probe and found it to be malfunctioning 3 h after placement before cardiopulmonary bypass. The arms were tucked by the side of the patient. The probe was moved to the index finger and still did not function when an ear probe was used for the rest of the case. We speculate that when the arms were tucked the probe was displaced, enclosing the finger from side to side instead of anteroposteriorly and resulting in compression of the digital vessels and nerves. The patient was not hypotensive during this period, which prevented probable ischemic damage. Neural compression produced the sensory loss of the terminal phalanx. In conclusion, we are reporting sensory loss localized to the terminal phalanx of the right middle finger, where the pulse oximeter probe was located in a patient undergoing CABG.
Rodney E. Gates, MD
Sandra B. Kinsella, MD
S. S. Moorthy, MD
Department of Anesthesia, Indiana University Medical Center, Indianpolis, IN 46202
1. Chemello PD, Nelson SR, Wolford LM. Finger injury resulting from pulse oximeter probe during orthognathic surgery. Oral Surg Oral Med Oral Pathol 1990;69:161-3.
2. Stogner SW, Owens MW, Baethge BA. Cutaneous necrosis and pulse oximetry. Cutis 1991;48:235-7.
3. Bashein G, Syrory G. Burns associated with pulse oximetry during magnetic resonance imaging. Anesthesiology 1991;75:382-3.
4. Shellock FG, Slimp GL. Severe burn of the finger caused by using a pulse oximeter during MR imaging. AJR Am J Roentgenol 1989;153:1105.