C. Lendl

G. von Hegel

G. Wiesner

H. Wiesner

R. Hipp

W. Erhardt

English

Erhardt, W.

Lendl, Christine

Hipp, R.

Hegel, G. von

Wiesner, Henning

Universität München: Elektronischen Publikationen

German

The use of pulse oximetry in clinical veterinary anaesthesia

Open Access LMU

J. Ass. vet. Anaesth. Vol. 17 (1990) The use of pulse oximetry in clinical veterinary anaesthesia W. Erhardt, C. Lendl, R. Hipp*, G. von Hegel**, G. and H . Wiesner* Institute for Experimental Surgery and institute for Anaesthesiology of the Technical University of Munich. **Tierpark Hellabrunn, Munich. SUMMARY A commercial human pulse oximeter was used in several species to measure heart rate and arterial oxygen saturation (Sa02), and the results compared with those from an ECG and bench oximeter. The heart rates were always the same, but differences in the Sa02 ranged between 4.2 per cent to 10.3 per cent. Correlation coefficients between the two Sa02 measurement techniques ranged from 0.81 to 0.94, depending on the species investigated. INTRODUCTION Pulse oximetry has been used for many years in human anaesthesia to provide a continuous and non-invasive measurement of oxygen saturation (Altemeyer, Mayer, Berg-Seiter and Fosel 1986; Barrington, Finer and Ryan 1988; Severinghaus and Naifen 1987; Yelderman and New 1983). Published studies of pulse oximetry in animals are, however, confined to dogs and are orientated towards the use of animals as experimental models of human disease (Sendak, Harris and Donham 1988; Tremper et al 1984) rather than the use of pulse oximetry in veterinary clinical practice. Pulse oximeters are potentially well suited to veterinary anaesthesia as they are easy to set up and give a useful amount of information. They detect desaturation long before cyanosis is apparent, giving warning of an impending problem. A variety of problems, both respiratory and circulatory, w i l l lead to arterial desaturation or poor peripheral pulse quality and wil l be indicated by the unit. This study reports on the use of a pulse oximeter in several species and compares the results w i t h those obtained from a bench oximeter. MATERIALS AND METHODS A Physio Control (Redmond, Washington, USA) pulse oximeter was used in these studies. The unit gave a continuous display of arterial haemoglobin oxygen saturation (Sa02) and pulse rate, with variable alarm limits for both these parameters. The Sa02 trend was displayed along w i t h a vertical bar graph which indicated the amplitude of the peripheral pulse signal. The unit could be operated from the mains or internal batteries. The studies were mostly performed in sedated or anaesthetised animals as the probe is susceptible to movement artefacts. The heart rate was recorded using a standard ECG monitor. Sa02 readings from the pulse oximeter were compared with the results obtained from analysis of arterial blood samples taken from the femoral or central ear artery via a catheter. The samples were analysed with a bench co-oximeter (Model 482, Instrumentation Laboratories, Lexington, Massachusetts, USA). Comparative studies were performed in rabbits, dogs, sheep, goats and pigs. For this study sheep and goats were considered together. The means ± sd of the differences between the two saturation measurements were calculated. The correlation between the two techniques was calculated by regression analysis. RESULTS The pulse rate indicated by the pulse oximeter was the same as that determined from the ECG. Sa02 measurements by co-oximetry were nearly always lower than those shown by the pulse oximeter. The mean differences range from 4.2 per cent to 10.3 per cent (Table 1). The lower the Sa02, the greater were the differences. Differences in Sa0 2 of up to 10 per cent were found when two identical pulse oximeters were applied to the tongue and lip in the same animal. Sa02 in the tongue was higher than the lip when the animal was well oxygenated and lower when the animal was poorly oxygenated. Regression analysis showed reasonable correlations between the two techniques (Figs la to Id) . The worst correlation (r = 0.81) was in rabbits and the best (r = 0.94) was in sheep and goats. DISCUSSION The pulse oximeter unit was able to produce a value for heart rate and Sa02 in all animals except the rat, in which it was unable to cope with the high heart rate (300 to 350 beats per min). The higher values of Sa02 produced by the pulse oximeter compared with the co-oximeter may be because the pulse oximeter also responds to methaemoglobin and carboxyhaemoglobin, although the levels of these forms of haemoglobin were not measured in this study. The bench co-oximeter can distinguish between the different types of haemoglobin (Altemeyer et al 1986). The shape of the haemoglobin dissociation curve wi l l also affect the accuracy of the pulse oximeter reading. The haemoglobin absorption spectrum of the dog is very similar to that in man (Sendak et al 1988); there are no Table 1: Differences between Sa0 2 measured by pulse oximeter and bench oximeter Difference in Sa0 2 (%) Species. . number mean SD dogs 52 10.3 6.5 rabbits 21 5.4 10.8 sheep/goats 51 7.3 3.5 Pigs 36 4.2 7.1 30 ä J. Ass. vet. Anaesth. Vol. 17 (1990) R e g r e s s i o n y = ax + b π = 21 β = 0.268 r a 0.8O7 b = 54.054 ρ < 0.01 χ 10 0.60 0.50 R e g r e s s i o n y = ax + b η » 52 β = 0 .7S8 r = 0 .922 2 b = 27 .354 ρ < 0.0 1 χ 10 0.30 ο CL 0.60 , ν 10 * 0.40 0.00 0.20 0.40 0.60 0.80 1.00 n 0-00 0-20 0.40 0.60 0.80 1.00 χ 10 ' 0, Hb t % 1 0, Hb [23 Regres s ι on y - ax b β « 0.719 χ 102 b » 23.054 = 36 - 0.830 < 0.01 R e g r e s s i o n y » ax + b a = 0.83G x 1 0 2 b = 13.800 Ο α. CO 0.50 0.70 0.20 0.40 0,Hb . 40 0 0. 40 0, Hb 0.60 Fig 1: Regression lines for arterial oxygen saturation measured by pulse oximetry (y axis) a g a i n s t haemoglobin s a t u r a t i o n measured by a bench co-oximeter (x axis), (a) rabbits; (b) pigs; (c) dogs; (d) sheep and goats previous reports of haemoglobin absorption spectra in other species. The co-oximeter used in this study measured haemoglobin saturation directly and was not affected by species differences in haemaglobin structure. The difference in values of Sa02 recorded from the lip and tongue may be an artefact produced by movement of muscle cells near to the arterioles. The different oxygen affinities of haemoglobin and myoglobin (Lendl) may thus contribute to the apparent differences in Sa02. The correlation between Sa0 2 as measured by pulse oximetry and co-oximetry was reasonably good, and the pulse oximeter gave a reliable indication of any changes in Sa02. A comparison of pulse oximetry, blood gas analysis and measurement of H b 0 2 via fibreoptic haemo-reflectometry showed that there was a high correlation between Sa02 measurements by the three techniques but there was sometimes a constant difference between the values (Erhardt et al 1989). The pulse oximeter has the advantage that a continuous, on-line result is available. It is much more practical than transcutaneous arterial oxygen tension measurements (Tremper et al 1984). Disadvantages of pulse oximetry are that it can only be used in calm or anaesthetised patients and it does not work with poorly perfused tissues. REFERENCES Altemeyer, K.H., Mayer, J., Berg-Seiter, S. and Fosel, T. (1986) Die Pulsoximetrie als kontinuierliches, nicht-invasives Uberwach-ungsverfahren - Ein Vergleich zweier Geräte. Anästhetist 35,43-45. Barrington, K.J., Finer, N.N. and Ryan, C A . (1988) Evaluation of pulse oximetry as a continuous monitoring technique in the neonatal intensive care unit. Critical Care Medicine 16,1147-1153. Erhardt, W., Lendl, C , Hipp, R., Schindele, Μ. and Blümel, G. (1989). Die Pulsoximetrie - ein nicht invasives Verfahren zur unmittelbaren und kontinuierlichen Überwachung von Sauerstoffsättigung und Pulsfrequenz-Vergleichsstudien zur Blutgasanalyse und zum Hämoreflektometer an Hund, Schwien und Schaf. Ben. Münch. Tierärtzl. Wschr. 102,289-292. Lendl, C. Zum Einsatz der Pulsoximetrie am Tier. Vet. Med. Diss., Munich - in preparation. Sendak, M.J., Harris, A.P. and Donham, R.T. (1988) Accuracy of pulse oximetry during arterial oxyhemoglobin desaturation in dogs. Anesthesiology 68,111-114. Severinghaus, J.W. and Naif en, K.H. (1987) Accuracy of response of six pulse oximeters to profound hypoxia. Anesthesiology 67,551-558. Tremper, K.K., Hufstedler, S., Zaccari, J., Schaefer, R., Asrani, R., Sangh, M., Roohk, V. and La Mendola, R. (1984) Pulse oximetry and transcutaneous Pcyz during haemorrhagic and normotensive shock in dogs. Anesthesiology 61, A163. Yelderman, M. and New, W. (1983) Evaluation of pulse oximetry. Anesthesiology 59,349-352. 31 

Accuracy of pulse oximetry during arterial oxyhemoglobin desaturation in dogs.

Accuracy of response of six pulse oximeters to profound hypoxia.

Die Pulsoximetrie - ein nicht invasives Verfahren zur unmittelbaren und kontinuierlichen Überwachung von

Die Pulsoximetrie als kontinuierliches, nicht-invasives Uberwachungsverfahren - Ein Vergleich zweier Geräte.

Evaluation of pulse oximetry as a continuous monitoring technique in the neonatal intensive care unit.

Evaluation of pulse oximetry.

Pulse oximetry and transcutaneous Pcyz during haemorrhagic and normotensive shock in dogs.

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The use of pulse oximetry in clinical veterinary anaesthesia

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