Continuous positive airway pressure (CPAP) decreases pulmonary shunt in anaesthetized horses.
Abstract: To evaluate the effects of continuous positive airway pressure (CPAP) on intrapulmonary shunt, cardiac output and oxygen delivery in horses subjected to a 6 hour period of general anaesthesia. Methods: Randomized, experimental, crossover study. Methods: Ten healthy adult horses. Methods: Following medetomidine, diazepam and ketamine administration, orotracheal intubation was performed and horses positioned in dorsal recumbency. Anaesthesia was maintained with isoflurane carried in an oxygen and air mix (FiO 0.5) combined with a medetomidine infusion. Horses were anaesthetized twice and either CPAP (8 cmH O) or physiologic airway pressure (NO CPAP) was applied to the lungs for 6 hours; the order of treatments was randomly assigned. Following induction of anaesthesia, cardiovascular and respiratory variables (including arterial blood gas analysis) were recorded every 30 minutes, cardiac output was measured every 60 minutes using the lithium dilution technique and oxygen delivery calculated. If PaCO exceeded 100 mmHg (13.3 kPa), controlled ventilation was initiated and horses excluded from further data collection. Groups were compared using a general linear model. Results: Data from eight horses were analysed. PaO was 15-56 mmHg (2.00-7.45 kPa) higher (p < 0.001) and shunt fraction 6-14% lower (p < 0.001) in the CPAP group. No differences were seen for cardiac output and oxygen delivery. The lack of difference in oxygen delivery was attributed to lower haemoglobin levels in the CPAP group than in the NO CPAP group. Conclusions: CPAP of 8 cmH O can be used in dorsally recumbent horses to decrease pulmonary shunt fraction without causing a decrease in cardiac output during longterm anaesthesia.
© 2016 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.
Publication Date: 2016-02-24 PubMed ID: 26913706DOI: 10.1111/vaa.12357Google Scholar: Lookup
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- Journal Article
- Randomized Controlled Trial
Summary
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The research assessed the influence of continuous positive airway pressure (CPAP) on intrapulmonary shunt, cardiac output, and oxygen delivery in horses that are anaesthetised for a long duration. The result of this study found that CPAP effectively reduced the pulmonary shunt fraction in these horses without any noticeable decrease in their cardiac output.
Methods and Procedures
- The study involved ten adult horses that were healthy. It was a crossover type experiment with randomization.
- The horses were anesthetized using a combination of medetomidine, diazepam, and ketamine, after which an orotracheal intubation procedure was performed.
- They were then laid on their backs (in dorsal recumbency). The anaesthesia was maintained with isoflurane, which was carried in a mixture of air and oxygen, along with a medetomidine infusion.
- The horses were subjected to a 6-hour period of general anaesthesia twice. In these sessions, either CPAP of 8cmH O or physiological airway pressure (NO CPAP) was applied to their lungs. The order of treatments was randomly assigned.
- Arterial blood gas analysis, along with other cardiovascular and respiratory variable monitoring was done every 30 minutes after inducing the anesthesia. Cardiac output was also measured every hour using the lithium dilution technique.
- If the partial pressure of carbon dioxide in their arterial blood (PaCO) exceeded 100 mmHg, controlled ventilation was initiated. Horses that reached this threshold were omitted from further data collection.
- A comparison between the CPAP group and the NO CPAP group was made using a general linear model.
Results and Conclusion
- Results obtained from eight horses were analysed. It was noted that the partial pressure of oxygen in their blood (PaO) was 2.00-7.45 kPa (15-56 mmHg) higher in the CPAP group as compared to the NO CPAP group. The shunt fraction was also 6-14% lower in this group.
- No significant variations were noticed in cardiac output and oxygen delivery between the two groups.
- The lack of difference in oxygen delivery is ascribed to the lower levels of haemoglobin in the group that was administered CPAP in comparison to the NON-CPAP group.
- From the collected data, the researchers concluded that CPAP with a pressure of 8 cmH O is effective in reducing the pulmonary shunt fraction in horses laid on their backs. This reduction was seen without any noticeable decrease in their cardiac output when the horses were subjected to long-term anaesthesia.
Cite This Article
APA
Mosing M, MacFarlane P, Bardell D, Lüthi L, Cripps PJ, Bettschart-Wolfensberger R.
(2016).
Continuous positive airway pressure (CPAP) decreases pulmonary shunt in anaesthetized horses.
Vet Anaesth Analg, 43(6), 611-622.
https://doi.org/10.1111/vaa.12357 Publication
Researcher Affiliations
- Division of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland. mmosing@vetclinics.uzh.ch.
- Langford Veterinary Services, University of Bristol, Bristol, UK.
- School of Veterinary Clinical Science, University of Liverpool, Neston, UK.
- Division of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
- School of Veterinary Clinical Science, University of Liverpool, Neston, UK.
- Division of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
MeSH Terms
- Anesthesia, Intravenous / veterinary
- Animals
- Cardiac Output / drug effects
- Cardiovascular System / drug effects
- Continuous Positive Airway Pressure / veterinary
- Cross-Over Studies
- Horses
- Lung / drug effects
- Oxygen
- Partial Pressure
- Prospective Studies
- Respiration / drug effects
Citations
This article has been cited 5 times.- Raidal SL, Catanchin CSM, Burgmeestre L, Quinn CT. Bi-Level Positive Airway Pressure for Non-invasive Respiratory Support of Foals. Front Vet Sci 2021;8:741720.
- Mosing M, Böhm SH, Rasis A, Hoosgood G, Auer U, Tusman G, Bettschart-Wolfensberger R, Schramel JP. Physiologic Factors Influencing the Arterial-To-End-Tidal CO(2) Difference and the Alveolar Dead Space Fraction in Spontaneously Breathing Anesthetised Horses. Front Vet Sci 2018;5:58.
- Mosing M, Waldmann AD, MacFarlane P, Iff S, Auer U, Bohm SH, Bettschart-Wolfensberger R, Bardell D. Horses Auto-Recruit Their Lungs by Inspiratory Breath Holding Following Recovery from General Anaesthesia. PLoS One 2016;11(6):e0158080.
- Bukoski A, Downs J, Hodgson DS, Le-Bert CR, Thomen R, Flors L, Thombs L, Bailey J. Cardiopulmonary effects of apneustic anesthesia ventilation in anesthetized pigs: a new mode of ventilation for anesthetized veterinary species. Front Vet Sci 2024;11:1378617.
- Yang Y, Jia D, Cheng L, Jia K, Wang J. Continuous positive airway pressure combined with small-tidal-volume ventilation on arterial oxygenation and pulmonary shunt during one-lung ventilation in patients undergoing video-assisted thoracoscopic lobectomy: A randomized, controlled study. Ann Thorac Med 2024 Apr-Jun;19(2):155-164.
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