SpO2 Threshold Research Articles

Oxygen saturation thresholds in managing sickle cell disease at US children's hospitals.

Adequate oxygen saturation (SpO2 ) is crucial for managing sickle cell disease (SCD). Children with SCD are at increased risk for occult hypoxemia; therefore, understanding SpO2 threshold practices would help identify barriers to oxygen optimization in a population sensitive to oxyhemoglobin imbalances. We investigated SpO2 cutoff levels used in clinical algorithms for management of acute SCD events at children's hospitals across the United States, and determined their consistency with recommended national guidelines (SpO2 >95%). Clinical pathways and algorithms used for the management of vaso-occlusive crisis (VOC) and acute chest syndrome (ACS) in SCD were obtained and reviewed from large children's hospitals in the United States. Responses were obtained from 94% (140/149) of eligible children's hospitals. Of these, 63 (45%) had available clinical algorithms to manage VOC and ACS. SpO2 cutoff was provided in 71.4% (45/63) of clinical algorithms. Substantial variation in SpO2 cutoff levels was noted, ranging from ≥90% to more than 95%. Only seven hospitals (5% of total hospitals and 15.6% of hospitals with clinical algorithms available) specified oxygen cutoffs that were consistent with national guidelines. Hospitals geographically located in the South (46.8%; n=29/62) and Midwest (54.8%; n=17/31) were more likely to have VOC and ACS clinical algorithms, compared to the Northeast (26.5%; n=9/34) and West (36.4%; n=8/22). There is inconsistency in the use of clinical algorithms and oxygen thresholds for VOC and ACS across US children's hospitals. Children with SCD could be at risk for insufficient oxygen therapy during adverse acute events.

Noninvasive Assessment of Impaired Gas Exchange with the Alveolar Gas Monitor Predicts Clinical Deterioration in COVID-19 Patients.

The COVID-19 pandemic magnified the importance of gas exchange abnormalities in early respiratory failure. Pulse oximetry (SpO2) has not been universally effective for clinical decision-making, possibly because of limitations. The alveolar gas monitor (AGM100) adds exhaled gas tensions to SpO2 to calculate the oxygen deficit (OD). The OD parallels the alveolar-to-arterial oxygen difference (AaDO2) in outpatients with cardiopulmonary disease. We hypothesized that the OD would discriminate between COVID-19 patients who require hospital admission and those who are discharged home, as well as predict need for supplemental oxygen during the index hospitalization. Patients presenting with dyspnea and COVID-19 were enrolled with informed consent and had OD measured using the AGM100. The OD was then compared between admitted and discharged patients and between patients who required supplemental oxygen and those who did not. The OD was also compared to SpO2 for each of these outcomes using receiver operating characteristic (ROC) curves. Thirty patients were COVID-19 positive and had complete AGM100 data. The mean OD was significantly (p = 0.025) higher among those admitted 50.0 ± 20.6 (mean ± SD) vs. discharged 27.0 ± 14.3 (mean ± SD). The OD was also significantly (p < 0.0001) higher among those requiring supplemental oxygen 60.1 ± 12.9 (mean ± SD) vs. those remaining on room air 25.2 ± 11.9 (mean ± SD). ROC curves for the OD demonstrated very good and excellent sensitivity for predicting hospital admission and supplemental oxygen administration, respectively. The OD performed better than an SpO2 threshold of <94%. The AGM100 is a novel, noninvasive way of measuring impaired gas exchange for clinically important endpoints in COVID-19.

Oxygen saturation thresholds for bronchiolitis at high altitudes: a cost-effectiveness analysis

ABSTRACT Background There is evidence suggesting that exaggerated reliance on pulse oximetry (SpO2) and the use of arbitrary/inadequate thresholds of SpO2 might drive unnecessary hospitalizations for viral bronchiolitis, especially among high-altitude residents. The aim of the present study was to compare the cost-effectiveness of two oxygen SpO2 thresholds for deciding whether infants with viral bronchiolitis living at high altitudes need hospital admission or can be discharged home. Methods A cost-effectiveness study was performed to compare the cost and clinical outcomes of two oxygen SpO2 thresholds, adjusted or not, to an altitude above the sea level of Bogota, Colombia (2640 m), for deciding whether infants with viral bronchiolitis need hospitalization or can be discharged home. The principal outcome was avoidance of hospital admission. Results Compared to the use of an SpO2 threshold of 90%, using an SpO2 threshold of 85% in infants with viral bronchiolitis was associated with lower overall costs (US$130.4 vs. US$194.0 average cost per patient) and a higher probability of hospitalization avoided (0.7500 vs. 0.5900), thus leading to dominance. Conclusions The use of an SpO2 threshold below 90% for deciding on hospitalization in infants with viral bronchiolitis living at high altitudes appears to be logical, secure, and cost-effective.

Descriptive characteristics of continuous oximetry measurement in moderate to severe covid-19 patients

Non-invasive oxygen saturation (SpO2) is a central vital sign used to shape the management of COVID-19 patients. Yet, there have been no report quantitatively describing SpO2 dynamics and patterns in COVID-19 patients using continuous SpO2 recordings. We performed a retrospective observational analysis of the clinical information and 27 K hours of continuous SpO2 high-resolution (1 Hz) recordings of 367 critical and non-critical COVID-19 patients hospitalised at the Rambam Health Care Campus, Haifa, Israel. An absolute SpO2 threshold of 93% most efficiently discriminated between critical and non-critical patients, regardless of oxygen support. Oximetry-derived digital biomarker (OBMs) computed per 1 h monitoring window showed significant differences between groups, notably the cumulative time below 93% SpO2 (CT93). Patients with CT93 above 60% during the first hour of monitoring, were more likely to require oxygen support. Mechanical ventilation exhibited a strong effect on SpO2 dynamics by significantly reducing the frequency and depth of desaturations. OBMs related to periodicity and hypoxic burden were markedly affected, up to several hours before the initiation of the mechanical ventilation. In summary, OBMs, traditionally used in the field of sleep medicine research, are informative for continuous assessment of disease severity and response to respiratory support of hospitalised COVID-19 patients. In conclusion, OBMs may improve risk stratification and therapy management of critical care patients with respiratory impairment.

Evaluation of the routine implementation of pulse oximeters into integrated management of childhood illness (IMCI) guidelines at primary health care level in West Africa: the AIRE mixed-methods research protocol

BackgroundThe AIRE operational project will evaluate the implementation of the routine Pulse Oximeter (PO) use in the integrated management of childhood illness (IMCI) strategy for children under-5 in primary health care centers (PHC) in West Africa. The introduction of PO should promote the accurate identification of hypoxemia (pulse blood oxygen saturation Sp02 < 90%) among all severe IMCI cases (respiratory and non-respiratory) to prompt their effective case management (oxygen, antibiotics and other required treatments) at hospital. We seek to understand how the routine use of PO integrated in IMCI outpatients works (or not), for whom, in what contexts and with what outcomes.MethodsThe AIRE project is being implemented from 03/2020 to 12/2022 in 202 PHCs in four West African countries (Burkina Faso, Guinea, Mali, Niger) including 16 research PHCs (four per country). The research protocol will assess three complementary components using mixed quantitative and qualitative methods: a) context based on repeated cross-sectional surveys: baseline and aggregated monthly data from all PHCs on infrastructure, staffing, accessibility, equipment, PO use, severe cases and care; b) the process across PHCs by assessing acceptability, fidelity, implementation challenges and realistic evaluation, and c) individual outcomes in the research PHCs: all children under-5 attending IMCI clinics, eligible for PO use will be included with parental consent in a cross-sectional study. Among them, severe IMCI cases will be followed in a prospective cohort to assess their health status at 14 days. We will analyze pathways, patterns of care, and costs of care.DiscussionThis research will identify challenges to the systematic implementation of PO in IMCI consultations, such as health workers practices, frequent turnover, quality of care, etc. Further research will be needed to fully address key questions such as the best time to introduce PO into the IMCI process, the best SpO2 threshold for deciding on hospital referral, and assessing the cost-effectiveness of PO use. The AIRE research will provide health policy makers in West Africa with sufficient evidence on the context, process and outcomes of using PO integrated into IMCI to promote scale-up in all PHCs.Trial registrationTrial registration number: PACTR202206525204526 retrospectively registered on 06/15/2022.

A method of determining anaerobic threshold from percutaneous oxygen saturation

The anaerobic threshold (AT) is the point of the aerobic-to-anaerobic metabolic switch. Despite the many clinical applications of AT, this measurement requires sophisticated equipment and skills. Here, we investigated a simple measurement method for AT using percutaneous oxygen saturation (SpO2) and pulse rate (PR) with a pulse oximeter in a study of exercise stress on healthy volunteers. Twenty individuals (ten men and ten women) were included in the study. Various respiratory parameters, including AT, were measured using conventional analytical methods. The SpO2 threshold (ST) was calculated using the SpO2-Slope method. The mean ± standard deviations SpO2 at ST was 97.8% ± 0.3% in men and 99.0 ± 0.3% in women. The concordance and interchangeability between ST and various five different types of AT, the ventilatory equivalent for oxygen (VE/VO2_AT), V-Slope (V-Slope_AT), ventilatory equivalent (VE_AT), respiratory exchange ratio (R_AT), and partial pressure of end-tidal oxygen (PETO2_AT) were generally high, with positive correlation coefficients in the range of [0.68–0.80]. These findings suggest that the SpO2-Slope method with a pulse oximeter may be a useful and simple method to determine AT compared to conventional methods.

Comparison of two oxygen saturation targets to decide on hospital discharge of infants with viral bronchiolitis living at high altitudes: a cost-effectiveness analysis

Objectives The objective of the current study was to evaluate the cost-effectiveness of two pulse oximetry (SpO2) thresholds to decide on hospital discharge when all other discharge criteria are met, in infants with viral bronchiolitis living at high altitudes. Methods A decision analysis model was developed to estimate the cost‐effectiveness of the use of an SpO2 threshold of 90% versus one of 85% for deciding whether infants hospitalized for viral bronchiolitis can be safely discharged to home, from a third-party payer´s perspective. The main outcome was discharge to home at day 4 of the initial hospitalization. The time horizon was 28 days after discharge from hospital. We performed deterministic sensitivity analyses and probabilistic sensitivity analyses. Results Compared to the use of an SpO2 threshold of 90%, treating infants with viral bronchiolitis with the use of an SpO2 threshold of 85% resulted in lower total costs (US$119.39 vs. US$188.357 mean cost per patient) and a greater probability of discharge to home at day 4 of the initial hospitalization (0.8400 vs. 0.7600), therefore being a dominant strategy. Sensitivity analyses were in line with base case results. Conclusions In Bogota, a high-altitude city, in infants admitted for viral bronchiolitis, the use of an SpO2 threshold of 85% to decide on hospital discharge when all other discharge criteria are met is dominant because it entails a greater probability of discharge to home at day 4 of the initial hospitalization and generates fewer costs than the use of an SpO2 threshold of 90%.

Understanding the “alarm problem” associated with continuous physiologic monitoring of general care patients

Study AimThe aim of this study is to investigate the impact of alarm configuration tactics in general care settings. MethodsRetrospective analysis of over 150,000 hours of medical/surgical unit continuous SpO2 and pulse rate data were used to estimate alarm rates and impact on individual nurses. ResultsApplication of an SpO2 threshold of 80% vs 88% produced an 88% reduction in alarms. Addition of a 15 second annunciation delay reduced alarms by an additional 71% with an SpO2 threshold of 80%. Pulse rate alarms were reduced by 93% moving from a pulse rate high threshold of 120–140 bpm, and 95% by lowering the pulse rate low threshold from 60 to 50 bpm. A 15 second annunciation delay at thresholds of 140 bpm and 50 bpm resulted in additional reductions of 80% and 81%, respectively. Combined alarm frequency across all parameters for every 24 hours of actual monitored time yielded a rate of 4.2 alarms for the surveillance configuration, 83.0 alarms for critical care monitoring, and 320.6 alarms for condition monitoring. Total exposure time for an individual nurse during a single shift ranged from 3.6 min with surveillance monitoring, to 1.2 hours for critical care monitoring, and 5.3 hours for condition monitoring. ConclusionsContinuous monitoring can eliminate unwitnessed/unmonitored arrests associated with significant increased mortality in the general care setting. The “alarm problem” associated with these systems is manageable using alarm settings that signify severely abnormal physiology to alert responsible clinicians of urgent situations.

Defining hypoxaemia from pulse oximeter measurements of oxygen saturation in well children at low altitude in Bangladesh: an observational study

BackgroundWHO defines hypoxaemia, a low peripheral arterial oxyhaemoglobin saturation (SpO2), as <90%. Although hypoxaemia is an important risk factor for mortality of children with respiratory infections, the optimal SpO2 threshold...

Predictive value of pulse oximetry for mortality in infants and children presenting to primary care with clinical pneumonia in rural Malawi: A data linkage study.

The mortality impact of pulse oximetry use during infant and childhood pneumonia management at the primary healthcare level in low-income countries is unknown. We sought to determine mortality outcomes of infants and children diagnosed and referred using clinical guidelines with or without pulse oximetry in Malawi. We conducted a data linkage study of prospective health facility and community case and mortality data. We matched prospectively collected community health worker (CHW) and health centre (HC) outpatient data to prospectively collected hospital and community-based mortality surveillance outcome data, including episodes followed up to and deaths within 30 days of pneumonia diagnosis amongst children 0-59 months old. All data were collected in Lilongwe and Mchinji districts, Malawi, from January 2012 to June 2014. We determined differences in mortality rates using <90% and <93% oxygen saturation (SpO2) thresholds and World Health Organization (WHO) and Malawi clinical guidelines for referral. We used unadjusted and adjusted (for age, sex, respiratory rate, and, in analyses of HC data only, Weight for Age Z-score [WAZ]) regression to account for interaction between SpO2 threshold (pulse oximetry) and clinical guidelines, clustering by child, and CHW or HC catchment area. We matched CHW and HC outpatient data to hospital inpatient records to explore roles of pulse oximetry and clinical guidelines on hospital attendance after referral. From 7,358 CHW and 6,546 HC pneumonia episodes, we linked 417 CHW and 695 HC pneumonia episodes to 30-day mortality outcomes: 16 (3.8%) CHW and 13 (1.9%) HC patients died. SpO2 thresholds of <90% and <93% identified 1 (6%) of the 16 CHW deaths that were unidentified by integrated community case management (iCCM) WHO referral protocol and 3 (23%) and 4 (31%) of the 13 HC deaths, respectively, that were unidentified by the integrated management of childhood illness (IMCI) WHO protocol. Malawi IMCI referral protocol, which differs from WHO protocol at the HC level and includes chest indrawing, identified all but one of these deaths. SpO2 < 90% predicted death independently of WHO danger signs compared with SpO2 ≥ 90%: HC Risk Ratio (RR), 9.37 (95% CI: 2.17-40.4, p = 0.003); CHW RR, 6.85 (1.15-40.9, p = 0.035). SpO2 < 93% was also predictive versus SpO2 ≥ 93% at HC level: RR, 6.68 (1.52-29.4, p = 0.012). Hospital referrals and outpatient episodes with referral decision indications were associated with mortality. A substantial proportion of those referred were not found admitted in the inpatients within 7 days of referral advice. All 12 deaths in 73 hospitalised children occurred within 24 hours of arrival in the hospital, which highlights delay in appropriate care seeking. The main limitation of our study was our ability to only match 6% of CHW episodes and 11% of HC episodes to mortality outcome data. Pulse oximetry identified fatal pneumonia episodes at HCs in Malawi that would otherwise have been missed by WHO referral guidelines alone. Our findings suggest that pulse oximetry could be beneficial in supplementing clinical signs to identify children with pneumonia at high risk of mortality in the outpatient setting in health centres for referral to a hospital for appropriate management.

Benefits and risks of oxygen therapy during acute medical illness: Just a matter of dose!

Oxygen therapy is used to reverse hypoxemia since more than a century. Current usage is broader and includes routine oxygen administration despite normoxemia which may result in prolonged periods of hyperoxemia. While systematic oxygen therapy was expected to be of benefit in some ischemic diseases such as stroke or acute myocardial infarction, recent randomised controlled trials (RCTs) have challenged this hypothesis by showing the absence of clinical improvement. Although oxygen is known to be toxic at high inspired oxygen fractions, a recent meta-analysis of RCTs revealed the life-threatening effect of hyperoxemia, with a dose-dependent relationship. Several recommendations have therefore been updated: (i) to monitor peripheral oxygen saturation (SpO2) as a surrogate for arterial oxygen saturation (SaO2); (ii) to initiate oxygen only when the lower SpO2 threshold is crossed; (iii) to titrate the delivered oxygen fraction to maintain SpO2 within a target range; and (iv) to stop supplying oxygen when the upper limit of SpO2 is surpassed, in order to prevent hyperoxemia. The lower and upper limits of SpO2 depend on the presence of risk factors for oxygen-induced hypercapnia (Chronic obstructive pulmonary disease, asthma, and obesity-associated hypoventilation). For patients at risk, oxygen therapy should be started when SpO2 is≤88% and stopped when it is>92%. For patients without risk factors, oxygen therapy should be started when SpO2 is≤92% and stopped when it is >96%. High-flow oxygen should only be used in a few diseases such as carbon monoxide poisoning, cluster headaches, sickle cell crisis and pneumothorax.

Predictors of obesity hypoventilation syndrome among patients with sleep-disordered breathing in India.

Introduction:No study has been done in India to evaluate obesity hypoventilation syndrome (OHS) among patients with sleep-disordered breathing (SDB). The known predictors of OHS, i.e., body mass index (BMI) >35 kg/m2 and forced vital capacity (FVC) <3.5 L for men and <2.3 L for women from western countries, cannot be applied to Indian patients.Objectives:To find out the prevalence of OHS and to determine the predictors of OHS among Indian SDB patients.Materials and Methods:It was a retrospective observational study conducted in a tertiary care institute from September 1, 2017, to August 31, 2018. All the patients who underwent polysomnography were analyzed for the presence of OHS. Of 85 patients referred for polysomnography, 76 had SDB. Thirteen patients were excluded because of hypoventilation due to other known causes or could not perform spirometry.Results:The prevalence of OHS among SDB after excluding the other causes of hypoventilation was 15.87% (10/63). The predictors were determined using univariate analysis between daytime partial pressure of carbon dioxide (PaCO2) and other predictors. PaCO2 significantly correlated with minimum nocturnal oxygen saturation by pulse oximetry (SpO2), FVC %predicted, BMI, daytime SpO2, forced expiratory volume %predicted, and partial pressure of oxygen (PaO2). Following a stepwise multiple regression, minimum nocturnal SpO2, FVC %predicted, and BMI were found to be independent predictors of OHS. A minimum nocturnal SpO2 threshold of 60%, FVC %predicted <74.5%, BMI >30.95 kg/m2, and absolute FVC <2.33 L for men and <1.68 L for women were found to be predictors of OHS.Conclusion:The prevalence of OHS in Indian patients is similar to Caucasians. OHS is seen in Indian patients even at a lower BMI and lower spirometric parameters.

Retrospective analysis of pulse oximeter alarm settings in an intensive care unit patient population

BackgroundThe cacophony of alerts and alarms in a hospital produced by medical devices results in alarm fatigue. The pulse oximeter is one of the most common sources of alarms. One of the ways to reduce alarm rates is to adjust alarm settings at the bedside. This study is aimed to retrospectively examine individual pulse oximeter alarm settings on alarm rates and inter- and intra- patient variability.MethodsNine hundred sixty-two previously collected intensive care unit (ICU) patient records were obtained from the Multiparameter Intelligent Monitoring in Intensive Care II Database (Beth Israel Deaconess Medical Center, Boston, MA). Inclusion criteria included patient records that contained SpO2 trend data sampled at 1 Hz for at least 1 h and a matching clinical record. SpO2 alarm rates were simulated by applying a range of thresholds (84, 86, 88, and 90 %) and delay times (10 to 60 s) to the SpO2 data. Patient records with at least 12 h of SpO2 data were examined for the variability in alarm rate over time.ResultsDecreasing SpO2 thresholds and increasing delay times resulted in decreased alarm rates. A limited number of patient records accounted for most alarms, and this number increased as alarm settings loosened (the top 10 % of patient records were responsible for 57.4 % of all alarms at an SpO2 threshold of 90 % and 15 s delay and 81.6 % at an SpO2 threshold of 84 % and 45 s delay). Alarm rates were not consistent over time for individual patients with periods of high and low alarms for all alarm settings.ConclusionPulse oximeter SpO2 alarm rates are variable between patients and over time, and the alarm rate and the extent of inter- and intra-patient variability can be affected by the alarm settings. Personalized alarm settings for a patient’s current status may help to reduce alarm fatigue for nurses.Electronic supplementary materialThe online version of this article (doi:10.1186/s12912-016-0149-3) contains supplementary material, which is available to authorized users.

Pulse Oximeter Oxygen Saturation in Prediction of Arterial Oxygen Saturation in Liver Transplant Candidates

Background:Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.Objectives:The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.Patients and Methods:Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.Results:Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.Conclusions:Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

A Conversion Formula for Comparing Pulse Oximeter Desaturation Rates Obtained with Different Averaging Times

ObjectiveThe number of desaturations determined in recordings of pulse oximeter saturation (SpO2) primarily depends on the time over which values are averaged. As the averaging time in pulse oximeters is not standardized, it varies considerably between centers. To make SpO2 data comparable, it is thus desirable to have a formula that allows conversion between desaturation rates obtained using different averaging times for various desaturation levels and minimal durations.MethodsOxygen saturation was measured for 170 hours in 12 preterm infants with a mean number of 65 desaturations <90% per hour of arbitrary duration by using a pulse oximeter in a 2–4 s averaging mode. Using 7 different averaging times between 3 and 16 seconds, the raw red-to-infrared data were reprocessed to determine the number of desaturations (D). The whole procedure was carried out for 7 different minimal desaturation durations (≥1, ≥5, ≥10, ≥15, ≥20, ≥25, ≥30 s) below SpO2 threshold values of 80%, 85% or 90% to finally reach a conversion formula. The formula was validated by splitting the infants into two groups of six children each and using one group each as a training set and the other one as a test set.ResultsBased on the linear relationship found between the logarithm of the desaturation rate and the logarithm of the averaging time, the conversion formula is: D2 = D1 (T2/T1)c, where D2 is the desaturation rate for the desired averaging time T2, and D1 is the desaturation rate for the original averaging time T1, with the exponent c depending on the desaturation threshold and the minimal desaturation duration. The median error when applying this formula was 2.6%.ConclusionThis formula enables the conversion of desaturation rates between different averaging times for various desaturation thresholds and minimal desaturation durations.

Accuracy of a third (Dolphin Voyager) versus first generation pulse oximeter (Nellcor N-180) in predicting arterial oxygen saturation and pulse rate in the anesthetized dog

ObjectiveTo compare the accuracy of a 3rd (Dolphin Voyager) versus 1st generation pulse oximeter (Nellcor N-180). Study designProspective laboratory investigation. AnimalsEight adult dogs. MethodsIn anesthetized dogs, arterial oxygen saturation (SpO2) was recorded simultaneously with each pulse oximeter. The oxygen fraction in inspired gas (FiO2) was successively reduced from 1.00 to 0.09, with re-saturation (FiO2 0.40) after each breathe-down step. After each 3-minute FiO2 plateau, SpO2 and pulse rate (PR) were compared with the fractional arterial saturation (SaO2) and PR determined by co-oximetry and invasive blood pressure monitoring, respectively. Data analysis included Bland-Altman (B–A) plots, Lin's concordance correlation factor (ρc), and linear regression models. ResultsOver a SaO2 range of 33–99%, the overall bias (mean SpO2 − SaO2), precision (SD of bias), and accuracy (Arms) for the Dolphin Voyager and Nellcor N-180 were 4.3%, 4.4%, and 6.1%, and 3.2%, 3.0%, and 4.3%, respectively. Bias increased at SaO2 < 90%, more so with the Dolphin Voyager (from 1.6% to 8.6%) than Nellcor N-180 (from 3.2% to 4.5%). The SpO2 readings correlated significantly with SaO2 for both the Dolphin Voyager (ρc = 0.94) and Nellcor N-180 (ρc = 0.97) (p < 0.001). Regarding PR, bias, precision, and accuracy (Arms) for the Dolphin Voyager and Nellcor N-180 were −0.5, 4.6, and 4.6 and 1.38, 4.3, and 4.5 beats minute−1, respectively. Significant correlation existed between pulse oximeter and directly measured PR (Dolphin Voyager: ρc = 0.98; Nellcor N-180: ρc = 0.99) (p < 0.001). Conclusions and clinical relevanceIn anesthetized dogs with adequate hemodynamic function, both instruments record SaO2 relatively accurately over a wide range of normal saturation values. However, there is an increasing overestimation at SaO2 < 90%, particularly with the Dolphin Voyager, indicating that 3rd generation pulse oximeters may not perform better than older instruments. The 5.4-fold increase in bias with the Dolphin Voyager at SaO2 < 90% stresses the importance of a 93–94% SpO2 threshold to ensure an arterial saturation of ≥90%. In contrast, PR monitoring with both devices is very reliable.