Abstract
Purpose
It has been reported that the actual flow from a syringe pump changes due to vertical movement of the pumpin vitro, but a direct study of thein vivo effects of fluid delivery irregularities caused by vertical pump displacement has not been performed. The aim of this study was to assess the influence of positional changes of the syringe pump on the internal pressure (IP) and flow from the circuit, and to examine blood pressure changes caused by pump movement in animals with or without hemorrhagic shock.
Methods
To simulate clinical conditions, we used a rabbit model. We first measured the changes in line IP and flow from the syringe pump after moving the pump 50 cm vertically upwards or downwards. With the same animal, we then recorded the blood pressure changes under these conditions during norepinephrine (NE) infusion, using a rabbit hemorrhagic shock (HS) model.
Results
Following downward movement of the syringe pump, the IP increased by 37.5 ± 4.0 mmHg and IP decreased by 37.3 ± 3.1 mmHg following upward movement of the syringe pump. In the rabbit HS model, movement downwards decreased systolic blood pressure (SBP) by -17 ± 6.9% (P < 0.001), while upward movement raised SBP by 45.7 ± 21.5% (P < 0.001) from baseline values. Conclusions: Vertical displacement of the syringe pump alters the flow due to a change of line I P, and blood pressure can be affected by pump movement during NE infusion.
Résumé
Objectif
On sait que le débit effectif dans la pompe à perfusion change avec le déplacement vertical de la pompe in vitro, mais aucune étude directe n’a été réalisée sur les effets in vivo de ľirrégularité du débit causée par le déplacement vertical de la pompe. Nous voulions évaluer ľinfluence des changements de position de la pompe à perfusion sur la pression interne (PI) et le débit provenant du circuit, et vérifier les changements de tension artérielle causés par le déplacement de la pompe chez des animaux soumis ou non à un choc hémorragique.
Méthode
Pour simuler les conditions cliniques, nous avons utilisé un modèle expérimental chez un lapin. Nous avons ďabord mesuré les changements de PI, dans le cathéter, et de débit provenant de la pompe à perfusion après avoir déplacé la pompe de 50 cm vers le haut ou vers le bas. Nous avons ensuite enregistré les modifications de tension artérielle dans ces conditions pendant la perfusion de norépinéphrine (NE) en utilisant un modèle de choc hémorragique (CH).
Résultats
Après le déplacement de la pompe vers le bas, la PI a augmenté de 37,5 ± 4,0 mmHg, mais la PI a baissé de 37,3 ± 3,1 mmHg après le déplacement vers le haut. Dans le cas du modèle de CH chez le lapin, le déplacement vers le bas a fait baisser la tension artérielle systolique (TAS) de -17 ± 6,9 % (P < 0,001), tandis que le déplacement vers le haut a fait monter la TAS de 45,7 ± 21,5 % (P< 0,001) par rapport aux valeurs de départ.
Conclusion
Le déplacement vertical de la pompe à perfusion modifie le débit en raison ďun changement de la PI du cathéter. La tension artérielle peut être modifiée par le mouvement de la pompe pendant la perfusion de NE.
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Igarashi, H., Obata, Y., Nakajima, Y. et al. Syringe pump displacement alters line internal pressure and flow. Can J Anesth 52, 685–691 (2005). https://doi.org/10.1007/BF03016554
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DOI: https://doi.org/10.1007/BF03016554