Abstract
Objective
To describe some cardiorespiratory effects of an inspiratory-to-expiratory (IE) ratio
of 1:1 compared with 1:3 in ventilated horses in dorsal recumbency.
Study design
Randomized crossover experimental study.
Animals
A total of eight anesthetized horses, with 444 (330–485) kg body weight [median (range)].
Methods
Horses were ventilated in dorsal recumbency with a tidal volume of 15 mL kg–1 and a respiratory rate of 8 breaths minute–1, and IE ratios of 1:1 (IE1:1) and 1:3 (IE1:3) in random order, each for 25 minutes
after applying a recruitment maneuver. Spirometry, arterial blood gases and dobutamine
requirements were recorded in all horses during each treatment. Electrical impedance
tomography (EIT) data were recorded in four horses and used to generate functional
EIT variables including regional ventilation delay index (RVD), a measure of speed
of lung inflation, and end-expiratory lung impedance (EELI), an indicator of functional
residual capacity (FRC). Results were assessed with linear and generalized linear
mixed models.
Results
Compared with treatment IE1:3, horses ventilated with treatment IE1:1 had higher mean
airway pressures and respiratory system compliance (p < 0.014), while peak, end-inspiratory and driving airway pressures were lower (p < 0.001). No differences in arterial oxygenation or dobutamine requirements were
observed. PaCO2 was lower in treatment IE1:1 (p = 0.039). Treatment IE1:1 resulted in lower RVD (p < 0.002) and higher EELI (p = 0.023) than treatment IE1:3.
Conclusions and clinical relevance
These results suggest that IE1:1 improved respiratory system mechanics and alveolar
ventilation compared with IE1:3, whereas oxygenation and dobutamine requirements were
unchanged, although differences were small. In the four horses where EIT was evaluated,
IE1:1 led to a faster inflation rate of the lung, possibly the result of increased
FRC. The clinical relevance of these findings needs to be further investigated.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Veterinary Anaesthesia and AnalgesiaAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Review of hypoxaemia in anaesthetized horses: predisposing factors, consequences and management.Vet Anaesth Analg. 2017; 44: 397-408
- Influence of inspiration to expiration ratio on cyclic recruitment and derecruitment of atelectasis in a saline lavage model of acute respiratory distress syndrome.Crit Care Med. 2015; 43: e65-e74
- 3D EIT image reconstruction with GREIT.Physiol Meas. 2016; 37: 785-800
- Other approaches to open-lung ventilation: airway pressure release ventilation.Crit Care Med. 2005; 33: S228-S240
- End-expiratory lung impedance change enables bedside monitoring of end-expiratory lung volume change.Intensive Care Med. 2003; 29: 37-43
- Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in the lateral decubitus position.Anaesth Intensive Care. 2012; 40: 1016-1022
- The effects of prolonged inspiratory time during one-lung ventilation: a randomised controlled trial.Anaesthesia. 2013; 68: 908-916
- In vitro validation of a Pitot-based flow meter for the measurement of respiratory volume and flow in large animal anaesthesia.Vet Anaesth Analg. 2009; 36: 209-219
- Tidal recruitment assessed by electrical impedance tomography and computed tomography in a porcine model of lung injury.Crit Care Med. 2012; 40: 903-911
- Physiological and inflammatory consequences of high and low respiratory rate in acute respiratory distress syndrome.Acta Anaesthesiol Scand. 2021; 65: 1013-1022
- Electrical impedance tomography to measure lung ventilation distribution in healthy horses and horses with left-sided cardiac volume overload.J Vet Intern Med. 2021; 35: 2511-2523
Article Info
Publication History
Published online: August 05, 2022
Accepted:
July 27,
2022
Received in revised form:
July 26,
2022
Received:
March 1,
2022
Identification
Copyright
© 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
