ISO 80601-2-61:2011 applies to the basic safety and essential performance of pulse oximeter equipment intended for use on humans, hereafter referred to as ME equipment. This includes any part necessary for normal use, including the pulse oximeter monitor, pulse oximeter probe, and probe cable extender. These requirements also apply to pulse oximeter equipment, including pulse oximeter monitors, pulse oximeter probes and probe cable extenders, which have been reprocessed. The intended use of pulse oximeter equipment includes, but is not limited to, the estimation of arterial oxygen haemoglobin saturation and pulse rate of patients in professional healthcare institutions as well as patients in the home healthcare environment. ISO 80601-2-61:2011 is not applicable to pulse oximeter equipment intended for use in laboratory research applications nor to oximeters that require a blood sample from the patient. ISO 80601-2-61:2011 can also be applied to pulse oximeter equipment and their accessories used for compensation or alleviation of disease, injury or disability. ISO 80601-2-61:2011 is not applicable to pulse oximeter equipment intended solely for foetal use. ISO 80601-2-61:2011 is not applicable to remote or slave (secondary) devices that display SpO2 values that are located outside of the patient environment.