bs_bs_banner CLINICAL PRACTICE GUIDELINES Clinical use of pulse oximetry: Official guidelines from the Thoracic Society of Australia and New Zealand JEFFREY J. PRETTO,1,2 TEANAU ROEBUCK,3 LUTZ BECKERT4,5 AND GARUN HAMILTON6,7 1Department of Respiratory & Sleep Medicine, John Hunter Hospital, 2School of Medicine & Public Health, University of Newcastle, Newcastle, New South Wales, 3Alfred Sleep Disorders & Ventilatory Failure Service, The Alfred, Prahran, 6Monash Lung and Sleep, Monash Medical Centre, 7Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia, 4Department of Respiratory Medicine, Canterbury District Health Board, and 5Department of Medicine, University of Otago, Christchurch, New Zealand ABSTRACT INTRODUCTION Pulse oximetry provides a simple, non-invasive approximation of arterial oxygenation in a wide variety Pulse oximetry has become a common practice in a of clinical settings including emergency and critical- variety of clinical situations and is now often part of care medicine, hospital-based and ambulatory care, standard patient observations. A good understanding perioperative monitoring, inpatient and outpatient of the principles of pulse oximetry and its clinical settings, and for specific diagnostic applications. Pulse utility is important in enabling safe and effective use of oximetry is of utility in perinatal, paediatric, adult and it as a vital sign.1,2 The aims of these guidelines are to geriatric populations but may require use of age- document the clinical applications, principles of use, specific sensors in these groups. It plays a role in the interpretation and limitations of pulse oximetry, to monitoring and treatment of respiratory dysfunction assist with incorporating pulse oximeter oxygen satu- by detecting hypoxaemia and is effective in guiding ration (SpO2) readings into the assessment of respira- oxygen therapy in both adult and paediatric popula- tory status and to inform clinicians which factors are tions. Pulse oximetry does not provide information important to consider when choosing and using an about the adequacy of ventilation or about precise oximeter. Oximetry measurements should always be arterial oxygenation, particularly when arterial oxygen considered in the clinical context, and appropriate levels are very high or very low. Arterial blood gas clinical judgement rather than complete reliance on analysis is the gold standard in these settings. Pulse oximetry readings should provide the basis of effective oximetry may be inaccurate as a marker of oxygenation patient management. These guidelines aim to inform in the presence of dyshaemoglobinaemias such as clinical staff of important considerations involved in carbon monoxide poisoning or methaemoglobinaemia pulse oximetry to enable optimum use and are to be where arterial oxygen saturation values will be overes- 3,4 timated. Technical considerations such as sensor posi- used as an adjunct to other professional guidelines. tion, signal averaging time and data sampling rates Although modern oximeters are capable of measuring may influence clinical interpretation of pulse oximetry more than SpO2, these guidelines will focus solely on readings. the measurement of haemoglobin oxygen saturation. Assessing the availability of oxygen for delivery to Key words: clinical medicine, guideline, hypoxemia, oxygen, the peripheral tissues is critical in the assessment and pulse oximetry. management of all patients at risk of respiratory dys- function. Adequate oxygen content in arterial blood, Abbreviations: ODI, oxygen desaturation index; OSA, satisfactory tissue perfusion, and effective tissue obstructive sleep apnoea; SpO2, pulse oximeter oxygen oxygen extraction and utilization are all essential saturation. components to ensuring normal organ function. Measurement of the oxygen content in arterial blood via blood gas analysis provides critical information about ventilation, pulmonary gas exchange and acid/ base status; however, it is invasive, can only provide intermittent assessment and is not available in all set- Correspondence: Jeff Pretto, Department of Respiratory & tings. The majority of oxygen carried in arterial blood Sleep Medicine, John Hunter Hospital, Hunter Region Mail Centre, Locked Bag 1, Newcastle, NSW 2310, Australia. Email: is reversibly bound to haemoglobin molecules. As [email protected] such, the percentage of haemoglobin molecules in Received 4 September 2013; accepted 18 September 2013 arterial blood that are bound with oxygen, referred to (Associate Editor: Chi Chiu Leung). as the SaO2, is a clinically relevant marker of oxygen © 2013 The Authors Respirology (2014) 19, 38–46 Respirology © 2013 Asian Pacific Society of Respirology doi: 10.1111/resp.12204 TSANZ guidelines for pulse oximetry 39 Table 1 List of clinical applications for pulse oximetry and issues to consider relevant to each application Use Setting Features/issues to consider Spot SpO2 Check ED, primary care, outpatient • Set long averaging times to minimize motion artefact observation (e.g. rehabilitation, • Pulsatile waveform display useful for checking signal quality oxygen clinic, pre-flight • Select most appropriate sensor/site (e.g. finger/earprobe) assessment and others) Detection of nocturnal Sleep laboratory • Use oximeter in ‘sleep’ mode or with alarms disabled breathing disorders in • Set averaging time to 3 s or less the laboratory • Set data sampling and storage rate to a minimum of 10 Hz • Ability to output data in real time to capture on polysomnograph system Detection of nocturnal Overnight domiciliary monitoring • Use oximeter in ‘sleep’ mode or with alarms disabled breathing disorders in • Set averaging time to 3 s or less the home setting • Set data sampling and storage rate to a minimum of 1 Hz • Adequate data storage capacity (minimum of 8 h) • Download/analysis software required for report generation Critical monitoring Intensive/high dependency care • Consider ABG sampling to assess PaCO2, pH and Hb status (adult) • Select oximeter with good motion artefact rejection • Consider using central sensor site • Set alarm levels appropriate for individual patient Critical monitoring Neonatal • Select oximeter with good motion artefact rejection (paediatric) intensive/high-dependency care • Consider using central sensor site • Set alarm levels appropriate for individual patient Screening or titration for Outpatient clinic, domiciliary care, • Set long averaging times to minimize motion artefact supplemental oxygen primary care Detection of exercise Exercise laboratory, pulmonary • Consider using central sensor site desaturation rehabilitation • Select oximeter with good motion artefact rejection • Set averaging time at medium to long (balance between motion artefact sensitivity and rapid desaturation detection) Non-critical monitoring Hospital ward • Set long averaging times to minimize motion artefact • Set alarm levels appropriate for individual patient Perioperative monitoring Operating theatre, recovery room • Set alarm levels appropriate for individual patient of oxygenation ABG, arterial blood gas; ED, emergency department; Hb, haemoglobin; PaCO2, arterial carbon dioxide partial pressure; SpO2, pulse oximeter oxygen saturation. delivery to the tissues. Pulse oximetry provides a 1400 m than at sea level, with a corresponding decre- 5 means for safe, simple, continuous and non-invasive ment of around 1.5% in SaO2. It is noteworthy that estimation of SaO2, referred to as SpO2. inspired oxygen pressures at cruising altitude in com- mercial jet aircraft are approximately three-quarters of that experienced at sea level. As a consequence, NORMAL VALUES FOR SpO2 oxygen saturation is reduced during flight and healthy subjects can be expected to exhibit resting SpO2 of 7 Normal values for SpO2 are not clearly established due around 92%. to variations in measurement technique, sensor site, device type, subject age, altitude and definitions of normality. However, the mean SaO2 from co-oximeter CLINICAL APPLICATIONS OF measurement of arterial blood in normal adults PULSE OXIMETRY breathing air at sea level ranges from 97.1% at 18 years of age to 95.4% at 70 years, with lower limits of normal The availability of pulse oximetry has revolutionized being 96–94%, respectively.5 monitoring of respiratory function, particularly given Paediatric normal values for SpO2 have also not that multiple or continuous measurements can be been clearly defined; however, normal sea level values obtained rapidly and non-invasively. Table 1 summa- of 97–99% have been reported for healthy infants and rizes the use of pulse oximetry in different clinical children, with slightly lower values (down to 93%) in situations. It is important to realize that hypoxaemia neonates and young infants.6 is not a surrogate for other respiratory signs. Hypox- The reduction in atmospheric pressure with altitude aemia correlates poorly with respiratory and heart results in reduced inspired oxygen tension, with cor- rates,8 and tachypnoea may be a better predictor of responding decreases in arterial oxygenation. In respiratory compromise in some patients.9 Neverthe- healthy adults, arterial oxygen partial pressure (PaO2) less, hypoxaemia provides information about the is approximately 20 mm Hg lower at an altitude of adequacy of gas exchange or ventilation and is an © 2013 The Authors Respirology (2014) 19, 38–46 Respirology © 2013 Asian Pacific Society of Respirology 40 JJ Pretto et al. independent predictor of mortality in acute illness.10,11 the