Diego A Portela, Stuart R McKenzie, Raiane A Moura, Margaret Gonzalez, Pablo A Donati, Ignacio Sandez, Joaquin Araos, Ludovica Chiavaccini, Elizabeth A Maxwell, Pablo E Otero
{"title":"The effects of positive end-expiratory pressure and end-inspiratory pause on dead space and alveolar ventilation in mechanically ventilated dogs.","authors":"Diego A Portela, Stuart R McKenzie, Raiane A Moura, Margaret Gonzalez, Pablo A Donati, Ignacio Sandez, Joaquin Araos, Ludovica Chiavaccini, Elizabeth A Maxwell, Pablo E Otero","doi":"10.1016/j.vaa.2025.08.038","DOIUrl":null,"url":null,"abstract":"<p><strong>Objective: </strong>To evaluate the effect of 5 cmH<sub>2</sub>O positive end-expiratory pressure (PEEP) and end-inspiratory pause (EIP) on airway dead space (V<sub>Daw</sub>) and its resultant effects on alveolar tidal volume (V<sub>Talv</sub>) and physiological dead space-to-tidal volume ratio (V<sub>D</sub>/V<sub>T</sub>) in dorsally recumbent anesthetized dogs.</p><p><strong>Study design: </strong>Prospective, controlled clinical study.</p><p><strong>Animals: </strong>Healthy adult dogs (n = 20, > 20 kg) undergoing elective surgery.</p><p><strong>Methods: </strong>Dogs were mechanically ventilated across three 5 minute phases: 1) without PEEP (PEEP<sub>OFF</sub>); 2) with 5 cmH<sub>2</sub>O PEEP (PEEP<sub>ON</sub>); and 3) with PEEP<sub>ON</sub> plus an EIP (30% of inspiratory time) (PEEP<sub>ON</sub>+EIP), allowing 15 minutes of stabilization between phases. During each phase, expired CO<sub>2</sub> tension and tidal volume (V<sub>T</sub>) were measured using volumetric capnography, and arterial blood gases assessed. V<sub>Daw</sub>, V<sub>Talv</sub> and V<sub>D</sub>/V<sub>T</sub> were calculated offline and compared between phases using mixed-effect linear models. Data are presented as mean ± standard deviation (95% confidence interval) and indexed to the predicted ideal body mass when appropriate.</p><p><strong>Results: </strong>The V<sub>T</sub> was 16.8 ± 1.7 (16.3-17.19) mL kg<sup>-1</sup>. PEEP<sub>ON</sub> significantly increased V<sub>Daw</sub> [7.9 ± 1.6 (7.1-8.6) to 8.4 ± 1.8 (7.6-9.3) mL kg<sup>-1</sup>; p = 0.001] and V<sub>D</sub>/V<sub>T</sub> [0.52 ± 0.1 (0.49-0.55)% to 0.55 ± 0.1 (0.52-0.59)%; p = 0.001]. PEEP<sub>ON</sub> decreased V<sub>Talv</sub> [8.9 ± 0.8 (8.6-9.4) to 8.3 ± 0.8 (7.9-8.7) mL kg<sup>-1</sup>; p = 0.001]. EIP reversed these changes, decreasing V<sub>Daw</sub> back to baseline [7.8 ± 1.6 (7.1-8.6) mL kg<sup>-1</sup>], resulting in V<sub>D</sub>/V<sub>T</sub> and V<sub>Talv</sub> returning to baseline values. Arterial PaCO<sub>2</sub> remained stable across phases.</p><p><strong>Conclusions and clinical relevance: </strong>Although PEEP increased V<sub>Daw</sub> and decreased V<sub>Talv</sub>, the addition of a 30% EIP mitigated these effects, suggesting that incorporating an EIP may be an effective strategy to optimize dead space and ventilation in dogs receiving mechanical ventilation with PEEP.</p>","PeriodicalId":23626,"journal":{"name":"Veterinary anaesthesia and analgesia","volume":" ","pages":""},"PeriodicalIF":1.9000,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Veterinary anaesthesia and analgesia","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1016/j.vaa.2025.08.038","RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"VETERINARY SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Objective: To evaluate the effect of 5 cmH2O positive end-expiratory pressure (PEEP) and end-inspiratory pause (EIP) on airway dead space (VDaw) and its resultant effects on alveolar tidal volume (VTalv) and physiological dead space-to-tidal volume ratio (VD/VT) in dorsally recumbent anesthetized dogs.
Study design: Prospective, controlled clinical study.
Methods: Dogs were mechanically ventilated across three 5 minute phases: 1) without PEEP (PEEPOFF); 2) with 5 cmH2O PEEP (PEEPON); and 3) with PEEPON plus an EIP (30% of inspiratory time) (PEEPON+EIP), allowing 15 minutes of stabilization between phases. During each phase, expired CO2 tension and tidal volume (VT) were measured using volumetric capnography, and arterial blood gases assessed. VDaw, VTalv and VD/VT were calculated offline and compared between phases using mixed-effect linear models. Data are presented as mean ± standard deviation (95% confidence interval) and indexed to the predicted ideal body mass when appropriate.
Results: The VT was 16.8 ± 1.7 (16.3-17.19) mL kg-1. PEEPON significantly increased VDaw [7.9 ± 1.6 (7.1-8.6) to 8.4 ± 1.8 (7.6-9.3) mL kg-1; p = 0.001] and VD/VT [0.52 ± 0.1 (0.49-0.55)% to 0.55 ± 0.1 (0.52-0.59)%; p = 0.001]. PEEPON decreased VTalv [8.9 ± 0.8 (8.6-9.4) to 8.3 ± 0.8 (7.9-8.7) mL kg-1; p = 0.001]. EIP reversed these changes, decreasing VDaw back to baseline [7.8 ± 1.6 (7.1-8.6) mL kg-1], resulting in VD/VT and VTalv returning to baseline values. Arterial PaCO2 remained stable across phases.
Conclusions and clinical relevance: Although PEEP increased VDaw and decreased VTalv, the addition of a 30% EIP mitigated these effects, suggesting that incorporating an EIP may be an effective strategy to optimize dead space and ventilation in dogs receiving mechanical ventilation with PEEP.
期刊介绍：
Veterinary Anaesthesia and Analgesia is the official journal of the Association of Veterinary Anaesthetists, the American College of Veterinary Anesthesia and Analgesia and the European College of Veterinary Anaesthesia and Analgesia. Its purpose is the publication of original, peer reviewed articles covering all branches of anaesthesia and the relief of pain in animals. Articles concerned with the following subjects related to anaesthesia and analgesia are also welcome:
the basic sciences;
pathophysiology of disease as it relates to anaesthetic management
equipment
intensive care
chemical restraint of animals including laboratory animals, wildlife and exotic animals
welfare issues associated with pain and distress
education in veterinary anaesthesia and analgesia.
Review articles, special articles, and historical notes will also be published, along with editorials, case reports in the form of letters to the editor, and book reviews. There is also an active correspondence section.
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