Abstract
Objective
To determine changes in distribution of lung ventilation with increasing intra-abdominal
pressure (IAP) from carbon dioxide (CO2) insufflation in standing sedated horses.
Study design
Prospective experimental study.
Animals
A group of six healthy adult horses.
Methods
Each horse was sedated with acepromazine, detomidine and butorphanol and sedation
maintained with a detomidine infusion. The horse was restrained in a stocks system
and a 32 electrode electrical impedance tomography (EIT) belt was wrapped around the
thorax at the fifth–sixth intercostal space. EIT images and arterial blood samples
for PaO2 and PaCO2, pH and lactate concentration were obtained during capnoperitoneum at 0 (baseline
A), 5, 8 and 12 mmHg as IAP increased and at 8, 5, 0 (baseline B) mmHg as IAP decreased.
At each IAP, after a 2 minute stabilization period, EIT images were recorded for ≥
2 minutes to obtain five consecutive breaths. Statistical analysis was performed using
anova for repeated measures with Geisser-Greenhouse correction and a Tukey’s multiple comparison
test for parametric data. The relationship between PaO2 and the center of ventilation in the ventral-dorsal (CoV-VD) and right-left (CoV-RL)
directions or total impedance change as a surrogate for tidal volume (ΔZVT) were tested using linear regression analysis. Significance was assumed when p ≤ 0.05.
Results
There were no significant changes in CoV-VD, CoV-RL, PaO2, PaCO2, lactate concentration, pH, heart rate and respiratory rate with targeted IAP. There
was a significant decrease in ΔZVT compared with baseline A at 5 mmHg IAP as IAP was increased.
Conclusions and clinical relevance
Capnoperitoneum causes a significant decrease in ΔZVT in standing sedated horses with increasing IAP.
Keywords
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Article info
Publication history
Published online: April 21, 2022
Accepted:
April 15,
2022
Received in revised form:
April 14,
2022
Received:
July 15,
2021
Identification
Copyright
© 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
