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A study of cardiovascular function under controlled and spontaneous ventilation in isoflurane-medetomidine anaesthetized horses


Kalchofner Guerrero, Karin S; Picek, S; Ringer, Simone Katja; Jackson, Michelle Amanda; Hässig, Michael; Bettschart-Wolfensberger, Regula (2009). A study of cardiovascular function under controlled and spontaneous ventilation in isoflurane-medetomidine anaesthetized horses. Veterinary Anaesthesia and Analgesia, 36(5):426-435.

Abstract

OBJECTIVE: To determine, in mildly hypercapnic horses under isoflurane-medetomidine balanced anaesthesia, whether there is a difference in cardiovascular function between spontaneous ventilation (SV) and intermittent positive pressure ventilation (IPPV).
STUDY DESIGN: Prospective randomized clinical study.
ANIMALS: Sixty horses, undergoing elective surgical procedures under general anaesthesia: ASA classification I or II.
METHODS: Horses were sedated with medetomidine and anaesthesia was induced with ketamine and diazepam. Anaesthesia was maintained with isoflurane and a constant rate infusion of medetomidine. Horses were assigned to either SV or IPPV for the duration of anaesthesia. Horses in group IPPV were maintained mildly hypercapnic (arterial partial pressure of carbon dioxide (PaCO(2)) 50-60 mmHg, 6.7-8 kPa). Mean arterial blood pressure (MAP) was maintained above 70 mmHg by an infusion of dobutamine administered to effect. Heart rate (HR), respiratory rate (f(R)), arterial blood pressure and inspiratory and expiratory gases were monitored continuously. A bolus of ketamine was administered when horses showed nystagmus. Cardiac output was measured using lithium dilution. Arterial blood-gas analysis was performed regularly. Recovery time was noted and recovery quality scored.
RESULTS: There were no differences between groups concerning age, weight, body position during anaesthesia and anaesthetic duration. Respiratory rate was significantly higher in group IPPV. Significantly more horses in group IPPV received supplemental ketamine. There were no other significant differences between groups. All horses recovered from anaesthesia without complications.
CONCLUSIONS: There was no difference in cardiovascular function in horses undergoing elective surgery during isoflurane-medetomidine anaesthesia with SV in comparison with IPPV, provided the horses are maintained slightly hypercapnic.
CLINICAL RELEVANCE: In horses with health status ASA I and II, cardiovascular function under general anaesthesia is equal with or without IPPV if the PaCO(2) is maintained at 50-60 mmHg.

Abstract

OBJECTIVE: To determine, in mildly hypercapnic horses under isoflurane-medetomidine balanced anaesthesia, whether there is a difference in cardiovascular function between spontaneous ventilation (SV) and intermittent positive pressure ventilation (IPPV).
STUDY DESIGN: Prospective randomized clinical study.
ANIMALS: Sixty horses, undergoing elective surgical procedures under general anaesthesia: ASA classification I or II.
METHODS: Horses were sedated with medetomidine and anaesthesia was induced with ketamine and diazepam. Anaesthesia was maintained with isoflurane and a constant rate infusion of medetomidine. Horses were assigned to either SV or IPPV for the duration of anaesthesia. Horses in group IPPV were maintained mildly hypercapnic (arterial partial pressure of carbon dioxide (PaCO(2)) 50-60 mmHg, 6.7-8 kPa). Mean arterial blood pressure (MAP) was maintained above 70 mmHg by an infusion of dobutamine administered to effect. Heart rate (HR), respiratory rate (f(R)), arterial blood pressure and inspiratory and expiratory gases were monitored continuously. A bolus of ketamine was administered when horses showed nystagmus. Cardiac output was measured using lithium dilution. Arterial blood-gas analysis was performed regularly. Recovery time was noted and recovery quality scored.
RESULTS: There were no differences between groups concerning age, weight, body position during anaesthesia and anaesthetic duration. Respiratory rate was significantly higher in group IPPV. Significantly more horses in group IPPV received supplemental ketamine. There were no other significant differences between groups. All horses recovered from anaesthesia without complications.
CONCLUSIONS: There was no difference in cardiovascular function in horses undergoing elective surgery during isoflurane-medetomidine anaesthesia with SV in comparison with IPPV, provided the horses are maintained slightly hypercapnic.
CLINICAL RELEVANCE: In horses with health status ASA I and II, cardiovascular function under general anaesthesia is equal with or without IPPV if the PaCO(2) is maintained at 50-60 mmHg.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Veterinary Clinic > Equine Department
05 Vetsuisse Faculty > Veterinary Clinic > Department of Farm Animals
Dewey Decimal Classification:570 Life sciences; biology
630 Agriculture
Language:English
Date:2009
Deposited On:26 Aug 2009 14:06
Last Modified:07 Mar 2019 08:25
Publisher:Wiley-Blackwell
ISSN:1467-7644
Additional Information:The definitive version is available at www.blackwell-synergy.com
OA Status:Green
Publisher DOI:https://doi.org/10.1111/j.1467-2995.2009.00477.x

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