A simple method to reduce pulse oximetry interference by surgical optical navigation systems.

Sir,

Optical navigation systems (ONS), used in the operating room for image-guided surgery, may interfere with the measurement of pulse oximetry. Both ONS and pulse oximetry use pulses of infrared light.[123] Infrared light does not penetrate the body, so it is recommended that the ONS be positioned on the opposite side to the pulse oximeter probe.[1] We have observed that in circumstances when this is not feasible, for example, when the ONS is used in the midline, there is interference on the plethysmogram when the ONS is switched on. In these cases, covering the pulse oximeter with aluminum foil is recommended.[12] We have verified the efficacy of using aluminum packaging for this purpose; it is easy to find aluminum foil packaging of objects, such as alcohol swabs and bispectral index sensors in the operating room [Figure 1]. We covered the pulse oximeter with such packaging and found that this technique was a very economical and effective means of reducing interference caused by the ONS. The ONS has the potential to complicate the safe conduct of anesthesia, but this is easily preventable. Should a pulse oximeter malfunction during image-guided surgery, we recommend covering it with aluminum packaging.

Figure 1

Interference on the plethysmogram caused by an optical navigation system: (a) Arterial pressure waveform. (b) Plethysmogram on the optical navigation system side, covered by aluminum alcohol swab packaging after the third beat. (c) Plethysmogram on the non optical navigation system side

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Conflicts of interest

There are no conflicts of interest.