Agreement of SpO2, SaO2 and ScO2 in anesthetized cynomolgus monkeys (Macaca fascicularis)

Accuracy of smartwatches for measuring heart rate and oxygen saturation in cynomolgus macaques compared to clinical standards

Continuous monitoring of physiological parameters in non-human primates (NHPs) necessitates a precise, non-invasive, and convenient method. This study aimed to validate the use of smartwatches with integrated pulse oximetry and heart rate (HR) monitoring capabilities for use in NHPs. Currently, the clinical standard for non-invasive continuous monitoring of peripheral oxygen saturation (SpO2) in NHPs has been the use of a transmittance pulse oximeter (TPO) affixed to a location of highly vascularized tissue. In a clinical setting, HR is monitored through electrocardiogram (ECG) or associated with SpO2 measurement from a TPO probe utilizing photoplethysmography technology. Challenges in obtaining precise readings with TPOs stem from technological limitations and probe placement restrictions. To address these limitations, simultaneous HR and SpO2 measurements were obtained from 15 cynomolgus macaques (Macaca fascicularis) using the Apple Watch 7 (AW 7), Apple Watch 9 (AW 9), and a clinical-grade TPO probe with integrated optical HR measurement technology (iM70, ELAN). Arterial blood gas (ABG) analysis was used as a reference method for SpO2. We found that a TPO device significantly underestimated SpO2 compared to the AW 7 and AW 9 when referenced against ABG values. Smartwatch-derived HR and SpO2 measurements demonstrated good agreement and minimal bias compared to the gold standard method. Overall, the AW 7 and AW 9 exhibited good agreement with clinical reference standards for HR and good agreement with the gold standard for SaO2 in sedated cynomolgus macaques.

Reliability, clinical performance and trending ability of a pulse oximeter and pulse co-oximeter, in monitoring blood oxygenation, at two measurement sites, in immobilised white rhinoceros (Ceratotherium simum)

BACKGROUND

Monitoring blood oxygenation is essential in immobilised rhinoceros, which are susceptible to opioid-induced hypoxaemia. This study assessed the reliability, clinical performance and trending ability of the Nonin PalmSAT 2500 A pulse oximeter's and the Masimo Radical-7 pulse co-oximeter's dual-wavelength technology, with their probes placed at two measurement sites, the inner surface of the third-eyelid and the scarified ear pinna of immobilised white rhinoceroses. Eight white rhinoceros were immobilised with etorphine-based drug combinations and given butorphanol after 12 min, and oxygen after 40 min, of recumbency. The Nonin and Masimo devices, with dual-wavelength probes attached to the third-eyelid and ear recorded arterial peripheral oxygen-haemoglobin saturation (SpO2) at pre-determined time points, concurrently with measurements of arterial oxygen-haemoglobin saturation (SaO2), from drawn blood samples, by a benchtop AVOXimeter 4000 co-oximeter (reference method). Reliability of the Nonin and Masimo devices was evaluated using the Bland-Altman and the area root mean squares (ARMS) methods. Clinical performance of the devices was evaluated for their ability to accurately detect clinical hypoxemia using receiver operating characteristic (ROC) curves and measures of sensitivity, specificity, and positive and negative predictive values. Trending ability of the devices was assessed by calculating concordance rates from four-quadrant plots.

RESULTS

Only the Nonin device with transflectance probe attached to the third-eyelid provided reliable SpO2 measurements across the 70 to 100% saturation range (bias - 1%, precision 4%, ARMS 4%). Nonin and Masimo devices with transflectance probes attached to the third-eyelid both had high clinical performance at detecting clinical hypoxaemia [area under the ROC curves (AUC): 0.93 and 0.90, respectively]. However, the Nonin and Masimo devices with transmission probes attached to the ear were unreliable and provided only moderate clinical performance. Both Nonin and Masimo devices, at both measurement sites, had concordance rates lower than the recommended threshold of ≥ 90%, indicating poor trending ability.

CONCLUSIONS

The overall assessment of reliability, clinical performance and trending ability indicate that the Nonin device with transflectance probe attached to the third-eyelid is best suited for monitoring of blood oxygenation in immobilised rhinoceros. The immobilisation procedure may have affected cardiovascular function to an extent that it limited the devices' performance.

Repeatability and accuracy of fingertip pulse oximeters for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate in anesthetized dogs breathing 100% oxygen

OBJECTIVE

To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in anesthetized dogs breathing 100% O₂.

ANIMALS

29 healthy client-owned anesthetized dogs undergoing various surgical procedures.

PROCEDURES

In randomized order, each of 7 FPOs or a reference pulse oximeter (PO) was applied to the tongue of each intubated anesthetized dog breathing 100% O₂. Duplicate measurements of oxygen saturation (Spo₂) and PR were obtained within 60 seconds of applying an FPO or PO. A nonparametric version of Bland-Altman analysis was used. Coefficient of repeatability was the interval between the 5th and 95th percentiles of the differences between duplicate measurements. Bias was the median difference, and the limits of agreement were the 5th and 95th percentiles of the differences between each FPO and the PO. Acceptable values for the coefficient of repeatability of Spo₂ were ≤ 6%. Agreements were accepted if the limits of agreement had an absolute difference of ≤ ± 3% in Spo₂ and relative difference of ≤ ± 10% in PR.

RESULTS

Coefficient of repeatability for Spo₂ was acceptable for 5 FPOs, but the limits of agreement for Spo₂ were unacceptable for all FPOs. The limits of agreement for PR were acceptable for 2 FPOs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that some FPOs may be suitable for accurately monitoring PRs of healthy anesthetized dogs breathing 100% O₂, but mild underestimation of Spo₂ was common.

Sedative and physiological effects of alfaxalone intramuscular administration in cynomolgus monkeys (Macaca fascicularis)

To evaluate the sedative and physiological effects of alfaxalone intramuscular (IM) administration, 12 healthy cynomolgus monkeys were administered single IM doses of alfaxalone at 0.625 mg/kg (ALFX0.625), 1.25 mg/kg (ALFX1.25), 2.5 mg/kg (ALFX2.5), 5 mg/kg (ALFX5), 7.5 mg/kg (ALFX7.5), or 10 mg/kg (ALFX10); saline was used as the control (CONT). The sedative effects were subjectively evaluated using a composite measure scoring system in six animals. Changes in respiratory rate, pulse rate, non-invasive blood pressure, percutaneous oxygen-hemoglobin saturation (SpO₂), and rectal temperature were observed after IM treatments in the other six animals. All animals were allowed to lay down following the ALFX5, ALFX7.5, and ALFX10 treatments, whereas lateral recumbency was achieved in only two animals after ALFX2.5 treatment and none after the CONT, ALFX 0.625, and ALFX1.25 treatments. The median time (interquartile range) to lateral recumbency was 6.5 min (5.3–7.8), 4.0 min (4.0–4.0), and 3.0 min (3.0–3.8), and the duration of immobilization was 27.5 min (19.0–33.8), 56.0 min (42.3–60.8), and 74.5 min (62.8–78.0) after the ALFX5, ALFX7.5, and ALFX10 treatments, respectively. Endotracheal intubation was achieved in all six animals after the ALFX7.5 and ALFX10 treatments. Dose-dependent decreases in respiratory rate, non-invasive blood pressure, SpO₂, and rectal temperature were observed, and the quality of recovery was smooth in all animals after the ALFX5, ALFX7.5, and ALFX10 treatments. Thus, alfaxalone IM induced a dose-dependent sedative effect in cynomolgus monkeys, but at higher doses, hypotension, hypoxemia, and hypothermia could be induced.

Evaluation of the reliability of pulse oximetry, at different attachment sites, to detect hypoxaemia in immobilized impala (Aepyceros melampus)

OBJECTIVE

Evaluation of the reliability of pulse oximetry at four different attachment sites compared to haemoglobin oxygen saturation measured by a co-oximeter and calculated by a blood gas analyser in immobilized impala.

STUDY DESIGN

Randomized crossover study.

ANIMALS

A total of 16 female impala.

METHODS

Impala were immobilized with etorphine or thiafentanil alone, or etorphine in combination with a novel drug. Once immobilized, arterial blood samples were collected at 5 minute intervals for 30 minutes. Then oxygen was insufflated (5 L minute^-1) intranasally at 40 minutes and additional samples were collected. A blood gas analyser was used to measure the arterial partial pressure of oxygen and calculate the oxygen haemoglobin saturation (cSaO₂); a co-oximeter was used to measure the oxygen haemoglobin saturation (SaO₂) in arterial blood. Pulse oximeter probes were attached: under the tail, to the pinna (ear) and buccal mucosa (cheek) and inside the rectum. Pulse oximeter readings [peripheral oxygen haemoglobin saturation (SpO₂) and pulse quality] were recorded at each site and compared with SaO₂ and cSaO₂ using Bland-Altman and accuracy of the area root mean squares (A_rms) methods to determine the efficacy. P value < 0.05 was considered significant.

RESULTS

Pulse quality was 'good' at each attachment site. SpO₂ measured under the tail was accurate and precise but only when SaO₂ values were above 90% (bias = 3, precision = 3, A_rms = 4). The ear, cheek and rectal probes failed to give accurate or precise readings (ear: bias = -4, precision = 14, A_rms = 15; cheek: bias = 12, precision = 11, A_rms = 16; and rectum: bias = 5, precision = 12, A_rms = 13).

CONCLUSIONS AND CLINICAL RELEVANCE

In order to obtain accurate and precise pulse oximetry readings in immobilized impala, probes must be placed under the tail and SaO₂ must be above 90%. Since SaO₂ values are usually low in immobilized impala, pulse oximeter readings should be interpreted with caution.

Development and clinical evaluation of a new sensor design for buccal pulse oximetry in horses

BACKGROUND

The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes.

OBJECTIVES

The objectives of this study were to 1) develop an improved sensor design for horses to be used at an appropriate anatomical site, and 2) evaluate this design in an experimental study.

STUDY DESIGN

In vivo experiment.

METHODS

A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed and used with the Nonin 2500A Vet pulse oximetry monitor. Thirteen anaesthetised warmblood horses were included into a desaturation protocol (100-70% SaO₂ ). SpO₂ and pulse frequency values were recorded, using SaO₂ calculated from blood gas analysis and invasive pulse frequency measurements as reference methods. Bias and precision were evaluated by calculations of the root mean square deviation (A_rms ). The agreement of the methods was tested with Bland-Altman analysis.

RESULTS

The quality of the pulse frequency readings determined the quality of the SpO₂ -readings. Good pulse signal strength resulted in a SpO₂ -accuracy comparable to that of the original sensor (Nonin 2000SL: A_rms = 3%; N1: A_rms = 3.60%; N2b: A_rms = 3.46%). Especially at heart rates ≤30 bpm, pulse rate readings that were about twice as high as the reference value occurred. Their exclusion from the dataset resulted in a pulse rate accuracy similar to that of the original sensor. Bland-Altman plots showed limits of agreement typical of pulse oximeters.

MAIN LIMITATIONS

The pulse frequency accuracy requires further improvement. The usability in clinical cases needs to be tested.

CONCLUSIONS

The new sensor design has been shown to be suitable for buccal pulse oximetry in horses.

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

OBJECTIVE

To compare the accuracy of a 3rd (Dolphin Voyager) versus 1st generation pulse oximeter (Nellcor N-180).

STUDY DESIGN

Prospective laboratory investigation.

ANIMALS

Eight adult dogs.

METHODS

In anesthetized dogs, arterial oxygen saturation (SpO(2)) was recorded simultaneously with each pulse oximeter. The oxygen fraction in inspired gas (FiO(2)) was successively reduced from 1.00 to 0.09, with re-saturation (FiO(2) 0.40) after each breathe-down step. After each 3-minute FiO(2) plateau, SpO(2) and pulse rate (PR) were compared with the fractional arterial saturation (SaO(2)) 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 (rho(c)), and linear regression models.

RESULTS

Over a SaO(2) range of 33-99%, the overall bias (mean SpO(2) - SaO(2)), precision (SD of bias), and accuracy (A(rms)) 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 SaO(2) < 90%, more so with the Dolphin Voyager (from 1.6% to 8.6%) than Nellcor N-180 (from 3.2% to 4.5%). The SpO(2) readings correlated significantly with SaO(2) for both the Dolphin Voyager (rho(c) = 0.94) and Nellcor N-180 (rho(c) = 0.97) (p < 0.001). Regarding PR, bias, precision, and accuracy (A(rms)) 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: rho(c) = 0.98; Nellcor N-180: rho(c) = 0.99) (p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

In anesthetized dogs with adequate hemodynamic function, both instruments record SaO(2) relatively accurately over a wide range of normal saturation values. However, there is an increasing overestimation at SaO(2) < 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 SaO(2) < 90% stresses the importance of a 93-94% SpO(2) threshold to ensure an arterial saturation of >or=90%. In contrast, PR monitoring with both devices is very reliable.