December 2004

Dear Readers: Here's the Article for this Month:

Name of article:

Pulse Oximetry in Supportive and Palliative Care

Author(s): Vora V.A. and Ahmedzai SH
Abstract: Supportive Care Cancer 2004; 12: 758-61

Respiratory problems are an important issue in the palliative care setting, not only from a diagnostic and therapeutic point of view but also from emotional-related aspects involving patients and families as well as caregivers. In clinical practice, particularly in patients with dyspnoea, it is often necessary to estimate arterial oxyhaemoglobin saturation (SaO2).

In this paper, Vora and Ahmedzai describe in detail the indications, limitations, accuracy and factors that may affect readings of pulse oximetry in different palliative care settings. Pulse oximetry is a non-invasive method for estimating arterial oxyhaemoglobin saturation (normal range of SaO2 is 90-100%), by utilising selected wavelengths of light. The best location for the pulse oximeter probe is the finger, the toe, the ear lobe and the bridge of the nose (only used in infants).

Pulse oximetry has various applications:

assessment of dyspnea

decisions regarding O2 therapy and monitoring of this treatment and other interventions

evaluation of SaO2 before and after opioid therapy as well as rescue doses of opioids

identification of aspiration in dysphagic patients

assessment of hypoxaemia in patients with severe drowsiness, confusion or in patients during exercise or rehabilitation

vascular assessment of patients with leg ulcers


Pulse oximetry may however not give accurate information in the following circumstances:

hypothermia, hypovolemia, peripheral vascular disease, severe anaemia (Hb level < 5 g/dL), marked tremors, abnormal haemoglobins (carboxyhaemoglobin and methaemoglobin), and when intravascular dyes such as methylene blue and fluorescein are present.

Moreover, pulse oximetry does not give specific information about the patient’s Hb level, the adequacy of ventilation and sensitive changes in oxygenation.

Why I chose this article

This article allows us to get to know better the benefits of a small instrument such a the pulse oximeter that is easy and useful to use in a palliative care setting. At present, the only established indication for supplemental oxygen in a cancer patient with dyspnea is when oxygen saturation is less than 90%.

Therapy with oxygen is efficient in patients with hypoxemia, whereas in patients without hypoxemia, efficacy of oxygen therapy for dyspnea is no different from air. Pulse oximetry is particularly indicated to evaluate the necessity, or not, to begin oxygen therapy particularly in care settings such as the patient’s own home where oxygen is not within reach.

Regards,

Carla Ripamonti, MD
Member of the Board of Directors, IAHPC