Assessment of consciousness during propofol anaesthesia in pigs

Llonch, Pol; Andaluz, Anna; Rodríguez, P.; Dalmau, Antoni; Jensen, EW; Manteca, Xavier; Velarde, Antonio

doi:10.1136/vr.d5643

Cited by 14 publications

(16 citation statements)

References 11 publications

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“…However, just after the loss of balance, 98.2% of the pigs showed muscular excitation, which could affect the IoC calculation. In fact, in pigs anaesthetized with propofol (which do not perform muscular excitation), the loss of balance occurred on average 7 s before the brain activity decrease (Llonch et al, 2011). The differences between both studies reveal that muscular excitation artefacts might delay the decrease of the IoC below basal levels, as the muscular movements embed the EEG recording with sparks of muscular activity that disrupt the IoC calculation.…”

Section: Discussionmentioning

confidence: 99%

“…The IoC was calculated by an algorithm based on the EEG and the ESR of the data recorded during the last 7 to 12 s (Cardenas, 2008). In order to correlate the time of the IoC to the onset of the behavioural and physiological reflexes, the IoC recordings were delayed an average of 10 s (Llonch et al, 2011).…”

Section: Facilitiesmentioning

confidence: 99%

“…Some studies suggest that N 2 can be used to stun pigs by anoxia (Dalmau et al, 2010b;Llonch et al, 2011). However, high concentration of N 2 (.90%) in atmospheric air has a low stability, defined as the capability of the gas to be sustained within the pit in the existing stunning systems without being displaced by atmospheric air (Dalmau et al, 2010a).…”

Section: Introductionmentioning

confidence: 99%

“…The IoCview R monitor is currently used in human patients (Revuelta et al 2008), but has also been used in pigs (Llonch et al, 2011). The wireless technology of the IoC-view R allows the assessment of the brain activity in non-restrained animals in conditions similar to those found in commercial slaughterhouses.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of unconsciousness in pigs during exposure to nitrogen and carbon dioxide mixtures

Llonch

Rodríguez

Jospin

et al. 2013

Animal

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The aim of this study was to assess unconsciousness in pigs during and after the exposure to gas mixtures of 70% nitrogen (N2) and 30% carbon dioxide (CO2) (70N30C), 80% N2 and 20% CO2 (80N20C) and 85% N2 and 15% CO2 (85N15C) compared with 90% CO2 in air (90C) by means of the Index of Consciousness®(IoC), their behaviour and the absence of brain stem reflexes. The experiment included three trials of 24 pigs divided into four groups according to the number of treatments. Half of the group was exposed for a short time and the other half for a long time (3 and 5 min for the N2/CO2 mixtures exposure and 2 and 3 min in 90C exposure, respectively). During exposure, the IoC and the electroencephalography suppression rate (ESR) were assessed, as well as the time to onset and percentage of gasping, loss of balance, vocalizations, muscular excitation and gagging. At the end of the exposure, the corneal reflex, rhythmic breathing and sensitivity to pain were each assessed at 10 s intervals for 5 min. Brain activity decreased significantly (P < 0.05) 37.60 s after the start of the exposure to 90% CO2, which was significantly earlier than in 70N30C, 80N20C and 85N15C exposure, (45.18 s, 46.92 s and 43.27 s, respectively). Before brain activity decreased, all pigs experienced gasping and loss of balance and a 98% muscular excitation. The duration of the muscular excitation was longer in animals exposed to 70N30C, 80N20C and 85N15C than 90C (P < 0.01). After a long exposure time, all animals exposed to 90C died, whereas the 30.4% of animals exposed to N2/CO2 gas mixtures survived. Pigs exposed to 85N15C recovered corneal reflex and sensitivity to pain significantly earlier than when exposed to 90C. Exposure to 90C causes a higher aversive reaction but a quicker loss of consciousness than N2/CO2 gas mixtures. Exposure to N2/CO2 gas mixtures causes a lower percentage of deaths and an earlier recovery of the brain stem activity than 90C, whereas the time to recover the cortical activity is similar. In conclusion, the inhalation of N2/CO2 gas mixtures reduces the aversion compared with high concentrations of CO2; however, the period of exposure for inducing unconsciousness may be longer in N2/CO2 gas mixtures, and the signs of recovery appear earlier, compared to CO2.

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Section: Discussionmentioning

confidence: 99%

Section: Facilitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of unconsciousness in pigs during exposure to nitrogen and carbon dioxide mixtures

Llonch

Rodríguez

Jospin

et al. 2013

Animal

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“…In fact, the appearance of low frequencies in the EEG and changes in EEG power were already considered good indicators of a change in brain activity in previous studies when animals were stunned with gas (EFSA, 2013) or even with other methods, such as electricity (Llonch et al, 2015) or the use of anaesthetics. For instance, Llonch et al (2011) found a change in brain activity 7 s after the loss of balance in pigs anaesthetised with propofol. Other parameters considered in the study of the EEG, and observed later ( Figure 5) were the moment in the first wave with a power equal to or lower than the 10% of the EEG basal value (from 70 s to 130 s) appearing, and the moment at which a continuous EEG with values under this 10% was observed (from 105 s to 300 s).…”

Section: Phase 2 Stunning Effectiveness Without Stickingmentioning

confidence: 99%

Use of high concentrations of carbon dioxide for stunning rabbits reared for meat production

et al. 2016

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An investigation was performed to determine whether high concentrations of carbon dioxide (CO 2 ) at 70-98% in atmospheric air are a suitable alternative for stunning rabbits compared to conventional approaches such as electronarcosis. Aversion to the gas and efficacy in causing prolonged unconsciousness and death were studied in a total of 480 rabbits by means of behavioural parameters, physiological indicators (presence of rhythmic breathing and corneal reflex) and electroencephalography (EEG, brain function). The use of any of the 4 studied concentrations of the gas caused more nasal discomfort and vocalisations than the use of atmospheric air (P<0.001). EEG activity confirmed that loss of posture is a good indicator of the onset of unconsciousness in rabbits exposed to CO 2 , occurring earlier (P<0.05) at 90 and 98% than at 70 and 80%. Rabbits showed signs of aversion for 15 s before the onset of unconsciousness, which occurred around 30 s after the beginning of the exposure to the gas, similar to species such as swine in which high concentrations of CO 2 are also used for stunning. CO 2 at 80 to 98% is suggested as a reasonable concentration range to induce a long state of unconsciousness and death in rabbits, while 70% CO 2 is not recommended because it requires too long duration of exposure (more than 360 s) to ensure effectiveness. Despite the advantages in terms of pre-stun handling and irreversibility, CO 2 is not free of animal welfare concerns. In consequence, a debate is necessary to ascertain if CO 2 can be considered a suitable alternative to stun rabbits, considering the advantages and drawbacks cited, quantified in the present study as 15 s of aversion (nasal discomfort and vocalisations) before losing posture.

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Usability of the SedLine® electroencephalographic monitor of depth of anaesthesia in pigs: a pilot study

Mirra

Casoni

Barge

et al. 2022

J Clin Monit Comput

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To investigate the usability of the SedLine® monitor in anaesthetized pigs. Five juvenile healthy pigs underwent balanced isoflurane-based general anaesthesia for surgical placement of a subcutaneous jugular venous port. The SedLine® was applied to continuously monitor electroencephalographic (EEG) activity and its modulation during anaesthesia. Computer tomography and magnetic resonance were performed to investigate the relationship between electrodes’ positioning and anatomical structures. The pediatric SedLine® EEG-sensor could be easily applied and SedLine®-generated variables collected. An EEG Density Spectral Array (DS) was displayed over the whole procedure. During surgery, the EEG signal was dominated by elevated power in the delta range (0.5–4 Hz), with an underlying broadband signal (where power decreased with increasing frequency). The emergence period was marked by a decrease in delta power, and a more evenly distributed power over the 4–40 Hz frequency range. From incision to end of surgery, mean SedLine®-generated values (± standard deviation) were overall stable [23.0 (± 2.8) Patient State Index (PSI), 1.0% (± 3.8%) Suppression Ratio (SR), 8.8 Hz (± 2.5 Hz) Spectral Edge Frequency 95% (SEF) left, 7.7 Hz (± 2.4 Hz) SEF right], quickly changing during emergence [75.3 (± 11.1) PSI, 0.0 (± 0.0) SR, 12.5 (± 6.6) SEF left 10.4 (± 6.6) SEF right]. Based on the imaging performed, the sensor does not record EEG signals from the same brain areas as in humans. SedLine®-DSA and -generated variables seemed to reflect variations in depth of anaesthesia in pigs. Further studies are needed to investigate this correlation, as well as to define the species-specific brain structures monitored by the EEG-sensor.

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Assessment of consciousness during propofol anaesthesia in pigs

Cited by 14 publications

References 11 publications

Assessment of unconsciousness in pigs during exposure to nitrogen and carbon dioxide mixtures

Assessment of unconsciousness in pigs during exposure to nitrogen and carbon dioxide mixtures

Use of high concentrations of carbon dioxide for stunning rabbits reared for meat production

Usability of the SedLine® electroencephalographic monitor of depth of anaesthesia in pigs: a pilot study

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