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The uptake of ISO-flurane by the foetal lamb in utero: Effect on regional blood flow

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Abstract

Because isoflurane has recently been approved for clinical use in anaesthesia, we have studied the effect of this agent in the foetus using the pregnant ewe as an animal model.

Eight pregnant ewes of 120–125 days gestation were surgically prepared with indwelling catheters and tracke-ostonty. Prior to anaesthesia, labelled microspheres were injected into the foetal circulation to determine cardiac output and regional blood flows to all organs. The ewes were anaesthetized with a constant inspired concentration of 2 .0 per cent isoflurane in oxygen. Blood samples were drawn to construct an uptake curve for both mother and foetus. At 60 and 96 minutes of anaesthesia, microspheres were injected into the foetal circulation to measure changes in organ blood flow from the control period.

Isoflurane crossed the placenta and appeared in the foetal circulation within two minutes. By 96 minutes, maternal and foetal arterial levels were 116.3 ± 9.9 and 99.3 ± 9.1 mEqIL (0.98 vol% and 0.75 vol%). There were no significant changes in foetal blood pressure or pulserate but foetal pH decreased significantly from 7,39 ± 0.02 to 7.26 ± 0.2 (mean ± SEM) and base excess decreased from -1.1 ± 1.5 to -6.2 ± 0.7. Foetal cardiac index decreased from 390.8 ± 26 9ml-kg-1 min-1 to 292.0 ± 13.8 after 96 minutes of anaesthesia. There were no significant changes in any of the maternal cardiovascular or acid-base parameters. In the foetal lamb, isoflurane anaesthesia produces foetal acidosis and decreases foetal cardiac index after 96 minutes of anaesthesia.

Résumé

L’ttpprobalion récente de F isoflurane pour usage clinique en anesthésie nécessitait une étude de ses effets sur te fœtus; elle fut réalisée sur la brebis gravide. Des sondes à demeure ont été installées par manœuvres chirurgicales sur huit brebis gravides de 120 à 125 jours qui furent aussi trachéotomisées. Avant l’ anesthésie, des microsphères marquées ont été injectées dans la circulation fœtale pour mesurer le débit cardiaque et les débits sanguins régionaux, Les brebis furent anesthésiée.s par inhalation d’une concentration inspirée constante de 2 pour cent d’ isoflurane dans l’ oxygène. Des échantillons furent prélevés pour tracer une courbe de capture tant pour la mère que pour le foetus. Après 60 et 96 minutes d’anesthésie, des microsphères furent injectées dans la circulation fœtale pour mesurer les changements de débits régionaux comparatifs à la période de contrôle. L’isoflurane a traversé le placenta et est apparu dans le sang fœtal en moins de deux minutes. A ta 96ième minute, les niveaux artériels maternels et fœtaux étaient respectivement de 116.3 ± 9.9etde99.3 ± 9.1 (0.98 vol pour cent et 0.75 vol. pour cent). ll n’y a pas eu de changements significatifs de la pression sanguine et du pouls fœtaux mais le pH a baissé de façon significative de 7.39 ± 0.02 à 7.26 ± 0.2 et l’ excès de base est passé de-1.1 ± 1.5 à -6.2 ± 0.7. L’index cardiaque fœtal a diminuéae390.8 ± 26.9mlkg-’ min-1 à292.0± 13.8 après 96 minutes d’ anesthésie, On n’a pas trouvé de changements significatifs dans les paramètres maternels cardiovasculaires et acido-basiques.

L’anesthésie à l’isofiurane produit chez le fœtus de la brebis de l’ acidose et diminue l’index cardiaque après 96 minutes d’anesthésie.

References

  1. 1

    Forrest JB, Buffington C, Calahan MK et al. A imilticentre clinical evaluation nf isnflurane. Can Anaesth Soc J, 1982; 29 (Supplement).

  2. 2

    Eger El. Isoflurane: A compendium and reference. Aireo Incorp, 1981.

  3. 3

    Vitche JF. A history of forane. Anesthesiology 1971; 35:4–7.

  4. 4

    Homi J, Konchigeri HN, EchenhoffJE, Linde HW. A new anesthetic agent - Forane: Preliminary observations in man. Anesth Analg 1972; 51:439–77.

  5. 5

    Greenstein LR, Hiel RA, Maize RI. Metabolism in vitro of enflurane, isofluranc and methoxyflurane. Anesthesiology 1975; 42:420–4.

  6. 6

    Cromwell TH, Slevens WC, Eger EI, II et al. The cardiovascular effects of compound 469 (Forane) during spontaneous ventilation and CO2 challenge in man. Anesthesiology 1971; 35:17–25.

  7. 7

    Johnston, RR, Eger El, II, Wilson C. A comparative interaction of epinephrine with enflurane, iso-flurane and halothane in man. Anesth Anaig 1976; 55:709–12.

  8. 8

    Stevens WC, Cromwell TH, Halsey MJ et al. The cardiovascular effects of a new inhalational agent, Forane, in human volunteers at constant arterial cai-bon dioxide tension. Anesthesiology 1971; 35:8–16.

  9. 9

    Tranow J, Eberlein HJ, Oser G et al. Influence of modern inhalational agents on hemodynamics, myo-caidial contractility, left ventricular volumes and myocardial oxygen supply. Anaesthetist 1977; 26:220–30.

  10. 10

    Palahniuk RJ, Shnider SM. Maternal and fetal cardiovascular and acid-base changes during halothane and isoflurane anesthesia in the pregnant ewe. Anesthesiology 1974; 41:462–72.

  11. 11

    Heyman BA, Payne BD, Hoffman JI et al. Blood flow measurements with cardiomiclide-labelled particles. Prog Cardiovas Dis 1977; 20:55–70.

  12. 12

    Davies D. A method of gas chromatography using electron-capture detection tor the determination of blood concentration of halothane, chloroform and trichloreythelene. Br J Anaesth 1978; 50:147–53.

  13. 13

    Biehl DR, Cote. J, Tweed WA et al. Uptake of halothane by the normal foetal lamb in utero. Can Anaesth Soc J 1983; 30:24–7.

  14. 14

    Meschia G. Normal exchange of respiratory gases across the sheep placenta in respiratory gas exchange and blood flow in the placenta, LD Lango and H Bartel (Eds) DHEW Publication (NIH) 73–361, p. 229, 1972.

  15. 15

    Biehl DR, Cote J, Tweed WA et al. The effect of halothane on regional blood flow and cardiac output in the normal fetal lamb in utero. Anes Anaig (in press).

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Author information

Correspondence to D. R. Biehl or R. Yarnell or J. G. Wade or D. Sitar.

Additional information

Supported in part by the St. Boniface Research Foundation, Grant no. RF-79-3 and the Medical Research Council of Canada, Grant No. MA-6735.

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Biehl, D.R., Yarnell, R., Wade, J.G. et al. The uptake of ISO-flurane by the foetal lamb in utero: Effect on regional blood flow. Can Anaesth Soc J 30, 581–586 (1983). https://doi.org/10.1007/BF03015226

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Key words

  • anaesthetics
  • volatile
  • isoflurane
  • anaesthesia
  • obstetric
  • uterus
  • blood flow