Evaluation of lung ventilation distribution using electrical impedance tomography in standing sedated horses with capnoperitoneum.
Abstract: To determine changes in distribution of lung ventilation with increasing intra-abdominal pressure (IAP) from carbon dioxide (CO) insufflation in standing sedated horses. Methods: Prospective experimental study. Methods: 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 PaO and PaCO, 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 PaO 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 (ΔZV) were tested using linear regression analysis. Significance was assumed when p ≤ 0.05. Results: There were no significant changes in CoV-VD, CoV-RL, PaO, PaCO, lactate concentration, pH, heart rate and respiratory rate with targeted IAP. There was a significant decrease in ΔZV compared with baseline A at 5 mmHg IAP as IAP was increased. Conclusions: Capnoperitoneum causes a significant decrease in ΔZV in standing sedated horses with increasing IAP.
Copyright © 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
Publication Date: 2022-04-21 PubMed ID: 35641422DOI: 10.1016/j.vaa.2022.04.004Google Scholar: Lookup
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- Journal Article
Summary
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This study investigates the changes in lung ventilation distribution in standing, sedated horses when subjected to increasing intra-abdominal pressure due to carbon dioxide insufflation. The primary finding was that this condition (capnoperitoneum) caused a significant decrease in the total impedance change (a proxy for tidal volume), but did not significantly impact many other measures including heart and respiratory rate.
Research Methodology
- The study involved six healthy adult horses which were sedated using acepromazine, detomidine, and butorphanol. Detomidine infusion was used to maintain sedation.
- The horses were restrained in a stocks system and an electrical impedance tomography (EIT) belt was wrapped around the thorax at the fifth-sixth intercostal space. EIT is an imaging technique that provides real time, dynamic images of the lung ventilation.
- Different parameters were monitored and recorded as the intra-abdominal pressure (IAP) increased due to intentional insufflation of carbon dioxide (capnoperitoneum). These parameters included EIT images, arterial blood samples, oxygen pressure (PaO), carbon-dioxide pressure (PaCO), pH, and lactate concentration.
- The IAP increased from 0 (the baseline) to 5, 8, and 12 mmHg; and later decreased back to 0. At each IAP, after a two-minute stabilization period, five consecutive breaths were recorded to capture changes in lung ventilation.
Statistical Analysis and Results
- ANOVA for repeated measures with Geisser-Greenhouse correction and Tukey’s multiple comparison test was used for parametric data.
- Linear regression analysis was performed to test the relationship between PaO and the center of ventilation in the ventral-dorsal and right-left directions, and tidal volume.
- Significance was assumed when the p-value was less than or equal to 0.05.
- The results showed no significant changes in the distribution of lung ventilation, PaO, PaCO, lactate concentration, pH, heart rate, and respiratory rate with the increase in targeted IAP.
- However, there was a significant decrease in the overall change in impedance (proxy for tidal volume) compared to baseline at 5 mmHg IAP as the IAP was increased.
Conclusion
- The study concludes that capnoperitoneum, or the intentional insufflation of the abdominal cavity with carbon dioxide, causes a significant decrease in tidal volume in standing, sedated horses as IAP increases. However, it does not significantly impact many other measures such as heart rate, respiratory rate, and pH among others.
Cite This Article
APA
Beazley SG, Focken A, Fernandez-Parra R, Thomas KL, Adler A, Duke-Novakovski T.
(2022).
Evaluation of lung ventilation distribution using electrical impedance tomography in standing sedated horses with capnoperitoneum.
Vet Anaesth Analg, 49(4), 382-389.
https://doi.org/10.1016/j.vaa.2022.04.004 Publication
Researcher Affiliations
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada. Electronic address: shannon.beazley@usask.ca.
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
- Veterinary Referral Hospital UCV, Department of Small Animal Medicine and Surgery, Faculty of Veterinary Medicine Catholic University of Valencia 'San Vicente Mártir', Valencia, Spain.
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
- Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada.
- Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
MeSH Terms
- Animals
- Electric Impedance
- Horses
- Lactates
- Lung
- Prospective Studies
- Respiration
- Tomography, X-Ray Computed
Citations
This article has been cited 1 times.- Andrade FSRM, Ambrósio AM, Rodrigues RR, Faccó LL, Gonçalves LA, Garcia Filho SG, Dos Santos RT, Rossetto TC, Pereira MAA, Fantoni DT. The optimal PEEP after alveolar recruitment maneuver assessed by electrical impedance tomography in healthy horses.. Front Vet Sci 2022;9:1024088.
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