Effect of low inspired oxygen fraction on respiratory indices in mechanically ventilated horses anaesthetised with isoflurane and medetomidine constant rate infusion

Taylor, A. G.; Seymour, C.

doi:10.1016/j.tvjl.2016.02.011

Cited by 6 publications

(6 citation statements)

References 52 publications

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“…As in the present study, other studies have found no advantage to the use of a reduced FIO2 in horses during mechanical ventilation (Hubbell et al 2011;Taylor et al 2016). In some studies, that reported a positive effect of a reduced FIO2 (Marntell et al, 2005;Schauvliege et al, 2015), horses were allowed to breathe spontaneously.…”

Section: Discussionsupporting

confidence: 55%

“…Several studies have shown a positive effect of a lower FIO2 on pulmonary gas exchange in mechanically ventilated horses (Staffieri et al, 2009;Levionnois et al, J o u r n a l P r e -p r o o f 2016) when FIO2 of 0.21-0.3 was compared to FIO2 higher than 0.9. It should be noted that studies that showed no benefit of using a reduced FIO2 administered an FIO2 equal or higher than 0.5 in the 'reduced FIO2' group (Hubbell et al 2011;and Taylor et al 2016). Also, differences in anaesthetic protocol could account for some of the discrepancies observed between studies.…”

Section: Discussionmentioning

confidence: 98%

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Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies

Rodriguez¹,

Grauw²,

Loon³

2021

Veterinary Anaesthesia and Analgesia

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 98%

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies

Rodriguez¹,

Grauw²,

Loon³

2021

Veterinary Anaesthesia and Analgesia

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“…Increased pulmonary shunting has also been observed during anesthesia involving a higher fraction of inspired oxygen (FiO 2 ) anesthesia (23,28,29). As the FiO 2 did not change during the experiment, the contribution of high FiO 2 induced intrapulmonary shunting would have been minimal.…”

Section: Discussionmentioning

confidence: 94%

Changes in Arterial Blood Pressure and Oxygen Tension as a Result of Hoisting in Isoflurane Anesthetized Healthy Adult Horses

et al. 2020

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Background: In anesthetized adult horses, changes in recumbency can influence the cardiovascular system but how arterial blood pressures and oxygen tension change in isoflurane anesthetized animals as a direct result of hoisting has not been investigated.Objective: To evaluate effects of hoisting on hemodynamic function and pulmonary gas exchange in isoflurane-anesthetized horses.Study Design: Prospective, experimental study.Methods: Six adult horses were anesthetized three times using isoflurane in pure oxygen (inspired fraction 0.9–1.0), and allowed breathing spontaneously in lateral recumbency. After 45 min horses were hoisted using a single hoist-hobble system for 5 min and returned into left lateral recumbency. Heart rate (HR), respiratory rate (RR), and systolic (SAP), diastolic (DAP), and mean arterial blood pressures (MAP) were measured every minute starting from 5 min before to 5 min after hoisting. Arterial blood gas samples were collected before, during, and after hoisting.Results: Significant changes in hemodynamic parameters and PaO2 but not PaCO2 were found between baseline recordings and measurements obtained during and early after hoisting. The MAP decreased within the 1st min of hoisting from a mean of 74 ± 17 mmHg at baseline to 57 ± 20 mmHg (p < 0.05). Thereafter, it rapidly recovered to baseline before continuing to rise to higher than baseline values and then remaining elevated for 5 min after horses were returned into lateral recumbency. Simultaneously, the HR increased by 6–9 beats per min during the initial 3 min of hoisting before returning close to baseline values (p < 0.05). The PaO2 decreased significantly from a mean of 324.9 ±137.0 mmHg at baseline to a mean of 141.3 ± 104.2 mmHg during hoisting (p < 0.001) without recovering any more to baseline values.Clinical significance: Hoisting an adult horse during or at the end of isoflurane anesthesia carries the risk of a precipitous, though short-lived (1–2 min), drop in arterial blood pressures and a persistent decrease in arterial oxygenation. While in systemically healthy animals the observed functional impairments were not life-threatening, they may be more severe in systemically compromised horses.Therefore, arterial blood pressures and oxygenation must be carefully monitored when hoisting sick equine patients during or at the end of inhalant anesthesia.

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“…Fourteen studies were excluded after critically evaluating them: one review [ 29 ]; five due to missing control/intervention allocation of the animals [ 30 , 31 , 32 , 33 , 34 ]; two studies [ 20 , 35 ] because injectable agents were used for the maintenance of anaesthesia; one with an FIO 2 of the interventional group above our pre-defined threshold of 0.6 [ 36 ]; and one retrospective study with an average FIO 2 of the control group below our threshold of 0.8 [ 37 ]. Furthermore, three more studies were excluded as other gases than nitrogen were used to decrease the FIO 2 : in two studies [ 21 , 38 ] the intervention group received a mixture of oxygen with helium, and in one study [ 39 ] the inspired mixture consisted of oxygen and nitrous oxide.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the Effect of the Inspired Oxygen Fraction on Blood Oxygenation during Inhalant Anaesthesia in Horses: A Systematic Review with Meta-Analysis

Savvas

Pavlidou

Braun

et al. 2021

Animals

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In anaesthetized horses, pronounced ventilation/perfusion mismatching often occurs. Several authors have investigated the effect of lower inspired oxygen fractions (FiO2) to reduce formation of absorption atelectasis. This systematic review compared the effects of low (<0.6) and high (>0.8) FiO2 on the arterial oxygen tension (PaO2), the alveolar-to-arterial oxygen tension difference (P(A-a)O2), and the PaO2/FiO2 ratio in horses during inhalation anaesthesia. Using the Systematic Review Protocol for Animal Intervention Studies, four experimental and one clinical investigations were deemed suitable for inclusion. A meta-analysis was performed on the four experimental studies. The PaO2 was significantly lower (p = 0.0007, mean difference −23.54 kPa, 95% CI −37.18, −9.90) with a lower FiO2. However, the P(A-a)O2 was also significantly lower (p < 0.00001, mean difference −20.80 kPa, 95% CI −26.28, −15.32) when using a low FiO2. For the PaO2/FiO2 ratio, only one study fitted the inclusion criteria, so no meta-analysis was performed. It is concluded that, while only a limited number of studies are available, the use of a higher FiO2 in horses during inhalation anaesthesia will result in higher levels of PaO2, but also a larger P(A-a)O2 difference. Further studies are needed to increase the level of evidence on this subject.

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Effect of low inspired oxygen fraction on respiratory indices in mechanically ventilated horses anaesthetised with isoflurane and medetomidine constant rate infusion

Cited by 6 publications

References 52 publications

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies

Changes in Arterial Blood Pressure and Oxygen Tension as a Result of Hoisting in Isoflurane Anesthetized Healthy Adult Horses

Evaluation of the Effect of the Inspired Oxygen Fraction on Blood Oxygenation during Inhalant Anaesthesia in Horses: A Systematic Review with Meta-Analysis

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