Alveolar-Arterial Oxygen Tension Differences in Anaesthetized Horses

Hall, L.W.; Gillespie, J. R.; Tyler, W. S.

doi:10.1093/bja/40.8.560

Cited by 164 publications

(130 citation statements)

References 8 publications

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“…General anaesthesia in horses may lead to hypoxaemia, hypercapnia and a large alveolar (A) 48 arterial (a) difference in the partial pressure of oxygen (P(A-a)O 2 ), even with maximal fractional 49 inspired oxygen (FiO 2 ) (Hall et al, 1968). The main causes of hypoxaemia during anaesthesia, 50 which can be difficult to treat, are intrapulmonary shunt and ventilation-perfusion (V A :Q) mismatch 51 (Rees et al, 2010).…”

Section: Introduction 47mentioning

confidence: 99%

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

Taylor

Seymour

2016

The Veterinary Journal

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Section: Introduction 47mentioning

confidence: 99%

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

Taylor

Seymour

2016

The Veterinary Journal

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“…In recent decades ventilation strategies were investigated in equine anaesthesia with the aim to counteract the extensive atelectasis and subsequent impairment of oxygenation commonly observed (Hall et al 1968, McDonell 1979. A key element is the application of alveolar recruitment manoeuvres (ARMs) during mechanical ventilation, which require transitory high airway pressures followed by positive end-expiratory pressure (PEEP).…”

Section: Introductionmentioning

confidence: 99%

Threshold valves to create positive end-expiratory pressure (PEEP) in conventional large animal anaesthesia ventilators and circuits

Küls¹,

Braun²,

Schramel³

et al. 2016

PHK

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Summary: The use of positive end-expiratory pressure (PEEP) and alveolar recruitment manoeuvres (ARMs) has become a promising treatment option for perioperative alveolar collapse and subsequent hypoxaemia in equine patients. Unfortunately, only the newest generation of large animal ventilators, not using the bag-in-the-box principle, are able to automatically create sufficiently high PEEP levels for horses. To create a large range of PEEP in the commonly used bag-in-the-box ventilators and breathing circuits, threshold resistor valves can be added. These devices built up an adjustable PEEP by creating a force against the expiratory gas flow, thereby establishing a constant threshold pressure. Examples are the underwater seal, the spring-loaded threshold valve and the magnetic valve. However, there are some important aspects that need to be considered when using these devices. The location of both the threshold resistor and the PEEP measuring device within the circuit will determine, if PEEP can be detected within the entire breathing system. Furthermore, the time it takes to establish a stable PEEP within the system depends on the type of the threshold valve, and may be influenced by several other factors, e.g. the total gas volume in the circle, the type of ventilator used and the individual horse's lungs. In an in vitro study using an artificial lung the onset of PEEP was dependent on the fresh gas flow used -the higher the fresh gas flow, the faster the onset of PEEP. However, in vivo, the onset of PEEP was independent of the fresh gas flow and was, compared to the in vitro study, significantly slower. It is therefore paramount to monitor the pressures within the circuit and carefully observe the time it takes to build up PEEP for each individual horse.

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“…General anaesthesia in the horse is accompanied by gas exchange impairment and development of hypoxaemia (Hall et al, 1968;Gillespie et al, 1969;Steffey et al, 1977;Trim and Wan, 1990;Whitehair and Willits, 1999). A decrease in PaO 2 and elevation of PaCO 2 is greater during spontaneous ventilation compared to mechanical ventilation (Hall et al, 1968;Gillespie et al, 1969).…”

mentioning

confidence: 99%

“…A decrease in PaO 2 and elevation of PaCO 2 is greater during spontaneous ventilation compared to mechanical ventilation (Hall et al, 1968;Gillespie et al, 1969).…”

mentioning

confidence: 99%

“…This is a consequence of redistribution of perfusion caused by the force of gravity, redistribution of inspired gas and hypoventilation of the dependent lung, a decrease in cardiac output, development of atelectasis and an increase in pulmonary shunt (Hall et al, 1968;Gillespie et al, 1969;Nyman et al, 1990;Trim and Wan, 1990;Moens et al, 1995Moens et al, , 1998. Atelectasis formation in dependent lung regions is considered to be the main cause of impaired arterial oxygenation (Nyman et al, 1990;Moens et al, 1995).…”

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confidence: 99%

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The effects of inhalation salbutamol administration on systemic and pulmonary hemodynamic, pulmonary mechanics and oxygen balance during general anaesthesia in the horse

Patschova¹,

Kabeš²,

Krisová³

2010

Vet. Med.

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ABSTRACT:This research aimed to determine the effect of aerosolized salbutamol administration on systemic and pulmonary hemodynamic, pulmonary mechanics and oxygen balance in healthy horses during general anaesthesia. Six healthy Thoroughbreds (body weight range 471-587 kg) underwent two general anaesthesias in dorsal recumbency with and without aerosolized salbutamol administration in randomized order with a one month washout period. The anaesthesia was induced by 1.1 mg/kg of xylazine, 0.02 mg/kg of diazepam and 2.2 mg/kg of ketamine, maintained with isoflurane in oxygen and air and horses were mechanically ventilated. Measurement of arterial and pulmonary arterial blood pressures, cardiac output and arterial and mixed venous blood gas analysis was carried out. Spirometry was performed using a Horse-lite. After achieving a steady state, baseline (T 0 ) values of cardiac output, systemic and pulmonary arterial blood pressures, heart rate, dynamic compliance, airway resistance and arterial and mixed venous blood gas values and pH were recorded in both groups. In the S-group (salbutamol), 2 µg/kg of aerosolized salbutamol were administered synchronously with inspirium into the tracheal tube. In both groups data were recorded at 15, 30, 45 and 60 min (T 15 , T 30 , T 45 , T 60 ) after the baseline. PaO 2 /FiO 2 ratio, oxygen consumption (VO 2 ), oxygen delivery (DO 2 ), pulmonary shunt values were calculated. Data were tested for normality and compared within each group: T 0 value with T 15 , T 30 , T 45 , T 60 values using Wilcoxon's test with Bonferoni correction (significance level 0.0125). For each time point, comparisons were made between the S-and C-groups (control) using Wilcoxon's test. In the S-group, there was a significant increase in values (mean ± SD) of cardiac output (l/min), T 0 (38 ± 7), a peak at T 15 (64 ± 25.5), significantly higher values persisted throughout the period of anaesthesia; heart rate (beats/min), T 0 (32 ± 2), T 15 (40 ± 6), T 30 (38 ± 5); DO 2 (l/min), T 0 (5.8 ± 0.8), a peak at T 15 (9.6 ± 3.2), significantly higher values persisted until the end of anaesthesia and VO 2 (l/min), T 0 (1.1 ± 0.5), T 30 (1.6 ± 0.7) and T 45 (1.8 ± 0.5). In the C-group, there was a significant decrease in values of PaO 2 /FiO 2 ratio from T 0 (176 ± 67) to a minimum at T 60 (114 ± 36) and in DO 2 from T 0 (6 ± 2.3) to a minimum at T 60 (4.3 ± 1.2). A comparison of the S-and C-groups did not reveal any difference in the baseline data. Subsequently, significantly higher values of cardiac output, heart rate, DO 2 , and the PaO 2 /FiO 2 ratio were found in the S-group compared to the C-group. Pulmonary arterial blood pressure was significantly lower in the S-group. Aerosolized salbutamol administration in healthy horses during general anaesthesia caused hemodynamic changes which resulted in an elevation of oxygen delivery. It can have a positive effect on arterial oxygenation, but the effect varies between individuals.

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Alveolar-Arterial Oxygen Tension Differences in Anaesthetized Horses

Cited by 164 publications

References 8 publications

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

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

Threshold valves to create positive end-expiratory pressure (PEEP) in conventional large animal anaesthesia ventilators and circuits

The effects of inhalation salbutamol administration on systemic and pulmonary hemodynamic, pulmonary mechanics and oxygen balance during general anaesthesia in the horse

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