PLETHYSMOGRAPHIC USE OF PULSE OXIMETER

Dear Editor.

Plethysmographie capabilities of pulse oximeter can be utilised to assess efficiency of peripheral microcirculation apart from its main use [1, 2]. We were able to assess adequacy of peripheral circulation after arterial injury at elbow following a supracondylar fracture of humerus in a 5 year old child. Brachial/radial artery injury is not uncommon following supracondylar fracture, which if remained unnoticed can result in a loss of limb. Palpatory method to assess adequacy of distal circulation has its own limitations and total reliance on it can prove to be disastrous. In this child we were unable to feel radial/ulnar pulse at wrist, therefore we utilised finger probe of pulse oximeter to assess adequacy of circulation in distal hand and compared it with healthy left hand. We noted significant difference in the SpO₂ values (injured hand 83-86% as compared to normal hand 94-96%). However SpO₂ values were never below 75 per cent which indicates presence of arterial pulsations. There was no obvious neurological deficit, so decision to manage conservatively was taken. We utilised finger probe for continuous SpO₂ assessment during next 24 hours. SpO₂ values showed gradual improvement over next 24 hours and reached normal values of 94 per cent. Surgical interference in a major arterial injury at elbow is not far from risk. Borderline cases of contusion or temporary spasm need no exploration but close observation. In such cases continuous SpO₂ measurements can give better idea about peripheral circulatory status than clinical assessment [3]. A deterioration in the SpO₂ values over a time gives correct idea about progress and extent of damage and appropriate decision can be taken. Gradual improvement in SpO₂ values in our case indicated temporary spasm or contusion, thus unnecessary exploration was avoided. We feel that in the present circumstances where doppler technique is not routinely available in our hospitals, therefore noninvasive monitoring of SpO₂ for atleast first 24 hours can be a better and safe method of assessing peripheral circulation, specially in borderline cases and children as oximetry has not only dignostic but prognostic value [4].