Comparison of anoxia with and without ebullism.

Bancroft, Richard W.; Cooke, Julian P.; Cain, S. M.

doi:10.1152/jappl.1968.25.3.230

Cited by 4 publications

(3 citation statements)

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“…86 87 Decompression has the potential to cause adverse effects and clinical signs. Potential 88 gross pathology can vary with the rate of decompression and final vacuum level 89 (Bankcroft and Dunn, 1965;Bankcroft et al, 1968;Catron et al, 1984). The pressure 90 curves used in LAPS produce slow decompression which minimises the risk of 91 discomfort, pain and suffering during the period before the animal loses consciousness 92 (Battula et al, 2008;Purswell et al, 2007;Vizzier-Thaxton et al, 2010).…”

Section: Introduction 67mentioning

confidence: 99%

Pathological consequences of low atmospheric pressure stunning in broiler chickens

Martin

McKeegan

Magee

et al. 2020

Animal

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21Low Atmospheric Pressure Stunning (LAPS) is a novel approach to pre-slaughter 22 stunning of chickens using progressive hypobaric hypoxia by the application of gradual 23 decompression (280s cycle) according to a set of prescribed pressure curves. LAPS 24 produces a non-recovery state. Concerns have been raised relating to the possible 25 pathological and welfare consequences of expansion of air in the body during LAPS. 26In a randomized trial we compared the gross pathology of broilers exposed to LAPS 27 with a control group euthanized by intravenous injection of pentobarbital sodium (60 28 mixed sex broilers per treatment). The birds were exposed to each treatment in triplets 29 and all birds were subject to necropsy examination to detect and score (1 to 5, minimal 30 to severe) haemorrhagic lesions or congestion for all major organs and cavities (e.g. 31 air sacs, joints, ears and heart) as well as external assessment for product quality (e.g. 32 wing tips). Behavioural data (latency to loss of posture and motionless) and chamber 33 cycle data (temperature, humidity, pressure and oxygen availability) confirmed that 34 LAPS had been applied in a manner representative of the commercial process. All of 35 the organs observed were structurally intact for both treatment groups. No lesions 36were observed in the external ears, oral cavity, tracheal lumen, crop, and air sacs of 37 birds from either treatment group. There was no difference between treatments in the 38 wingtips, nasal turbinates, thymus, biceps femoralis, and colon. Haemorrhagic lesions 39 were observed in the calvaria, brains, hearts and lungs of both treatment groups, but 40 lesions in these areas were more severe in the LAPS treatment group. It was not 41 possible to distinguish between pathological changes induced by decompression or 42 recompression. In the barbiturate group, more severe haemorrhagic lesions were 43 observed in the superficial pectoral muscles as well as greater congestion of the 44 infraorbital sinuses, liver, spleens, duodenum, kidneys and gonads. These findings 45 provide evidence that LAPS did not result in distension of the intestines and air sacs 46 sufficient to cause changes, which were grossly visible on post mortem examination. 47There was also no evidence of barotrauma in the ears and sinuses. The pathological 48 changes observed in the barbiturate treatment were as expected based on barbiturate 49toxicity. LAPS appears to produce pathological changes by a variety of well-50 established mechanisms, and while these pathological data have limited value as 51 welfare indicators, the results confirm that organ integrity was not compromised by the 52 process. 53 54

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Section: Introduction 67mentioning

confidence: 99%

Pathological consequences of low atmospheric pressure stunning in broiler chickens

Martin

McKeegan

Magee

et al. 2020

Animal

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“…Additionally, pigs are susceptible to lung lesions and respiratory problems (10,20), which may result in pain and distress during decompression as well as influence their responses to hypoxia. Encouragingly, studies in poultry have demonstrated that LAPS has no detrimental impact on meat quality (21)(22)(23) and that there is no compromise to organ integrity (15), but these effects are likely to be species specific and the rate of decompression as well as the final vacuum pressure is crucial for mitigating pathological and clinical issues (24)(25)(26). In humans, slow rates of decompression may be associated with clinical signs such as tooth and middle ear pain, abdominal discomfort and joint pain but these are more common with descent of aircraft than ascent (27)(28)(29)(30).…”

Section: Introductionmentioning

confidence: 99%

Characterizing candidate decompression rates for hypobaric hypoxic stunning of pigs. Part 2: Pathological consequences

Baxter

McKeegan²,

Farish³

et al. 2022

Front. Vet. Sci.

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Pigs are commonly stunned pre-slaughter by exposure to carbon dioxide (CO2), but this approach is associated with significant welfare concerns. Hypobaric hypoxia, achieved with gradual decompression (also known as Low Atmospheric Pressure Stunning or LAPS) may be an alternative, allowing the retention of welfare friendly handling approaches and group stunning. Although validated in poultry, the feasibility and welfare consequences of gradual decompression for pigs are unknown. Here, we characterize pathological changes in 60 pigs resulting from exposure to a range of candidate decompression curves (ranging from 40 to 100 ms−1 ascent equivalent, with two cycle durations 480 and 720 s). To protect welfare, we worked on unconscious, terminally anesthetized pigs which were subject to detailed post-mortem examinations by a specialized porcine veterinary pathologist. All pigs were killed as a result of exposure to decompression, irrespective of cycle rate or length. Pigs showed no external injuries during ante-mortem inspections. Exposing pigs to decompression and the unavoidable subsequent recompression resulted in generalized congestion of the carcass, organs and body cavities including the ears, oral cavity, conjunctivae and sclera, mucosa of other external orifices (anus and vulva), nasal planum, nasal cavities including nasal conchae, frontal sinuses, cranium, meninges, brain, larynx, trachea, lungs, heart, parietal pleura of the thoracic cavity, peritoneum of the abdominal cavity, stomach, small intestine, caecum, colon, liver, spleen and kidneys and representative joint cavities in the limbs (stifles and elbows). Various severities of hemorrhage were observed in the conjunctivae and sclera, mucosa of other external orifices (anus and vulva), nasal cavities including nasal conchae, frontal sinuses, cranium, meninges, brain, larynx, tracheal lumen, lungs, parietal pleura of the thoracic cavity, liver, spleen and kidneys and representative joint cavities in the limbs (stifles and elbows). In general, faster decompression rates produced higher scores, but in the conjunctivae, sclera and kidneys, faster decompression rates were associated with marginally lower congestion scores. There was considerable individual variation in pathological scores across all body regions. The congestion and hemorrhage observed could translate into welfare harms in conscious pigs undergoing this type of stunning, depending when in the cycle the damage is occurring, but no welfare related conclusions can be drawn from the responses of unconscious pigs. Since recompression is always required, its effects cannot be separated from decompression, however cessation of cardiac activity several minutes before recompression should have eliminated any haemodynamic effects relating to cardiac function and blood pressure. This study represents the first systematic attempt to identify candidate rate profiles to underpin future explorations of decompression as a stunning method for pigs. These pathological findings also inform discussions about the likely carcass quality implications of this novel stunning method.

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“…During and immediately after World War 11, studies to pressures equivalent to about 72,000 f t (30 Torr) ascertained that general circulation ceased within less than 16 sec (1-4). More recently, it has been reported that vascular (5)(6)(7)(8) and biochemical (9) changes measured at pressures approaching a vacuum are generally of greater magnitude than those measured at 30 Torr, and decompressions to 2 Torr within 1 sec result in circulatory arrest within a few seconds, as evaluated by bloodpressure gradients ( 5 , 7 ) . The present study is designed to investigate the direction and distribution of pulmonary blood flow during such an exposure, where ordinary techniques and methods of measurement are either difficult or unreliable owing to artifacts associated with pressures that are less than that of water vapor.…”

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confidence: 99%