Eddie Clutton

The effect of environment on behaviour, plasma cortisol and prolactin in parturient sows

Nest-building in the pig is thought to be stimulated by a pre-parturient surge in prolactin. There is concern that sows in crates may experience psychological stress as a result of physical interference with nest-building. Thirty-three gilts were implanted with jugular catheters approximately 10–14 days before expected date of parturition (EPD). On day 5 before EPD, gilts were moved into either conventional farrowing crates without bedding (treatment C; n=16) or pens allowing freedom of movement with bedding (treatment P; n=17). The animals were blood sampled on the day before and the day after introduction to the treatments. Blood and behaviour sampling was resumed 48 h before EPD and continued until 4 h post-commencement of farrowing. As with previous studies gilts in both environments were more active (P<0.001) and performed more substrate-directed behaviour in the pre-parturient period (P<0.001). Gilts in pens spent considerable amounts of time in straw-directed behaviour, and gilts in crates increased amounts of floor- and fixture-directed behaviour (both P<0.001). Prolactin was not affected by treatment and increased in both environments over the same time period as this substrate-directed behaviour. However, the causal role of prolactin in nest-building must now be questioned given that a number of individuals showed no increase in prolactin over the 48 h before EPD, but still showed an increase in substrate-directed activity. Cortisol was strongly affected by treatment with treatment C having elevated total cortisol over much of the pre-parturient period (P<0.001). Cortisol also increased in penned animals during parturition. There were no consistent correlations among behaviour, prolactin and cortisol. The general increase in cortisol in the early post-partum period may suggest that parturition in itself has stress-inducing aspects. The additional rise in cortisol found in the crated sows may indicate that the close confinement of the crate, by interfering with the expression of maternal behaviour, induces psychological stress. There was no evidence that the elevated cortisol response in crated gilts extended beyond the end of parturition.

Clinical effects of isoflurane and sevoflurane in lambs

OBJECTIVE To compare isoflurane and sevoflurane in lambs undergoing prolonged anaesthesia for spinal surgery. STUDY DESIGN Prospective randomised clinical study. ANIMALS Eighteen Scottish blackface lambs 3-6 weeks of age and weighing 10-17 kg. METHODS After intramuscular medetomidine, anaesthesia was induced and maintained with either isoflurane (group I) or sevoflurane (group S) delivered in oxygen. Meloxicam, morphine, a constant rate infusion of ketamine and atracurium were given intravenously (IV) during surgery. Lungs were ventilated to maintain normocapnia. with peak inspiratory pressures of 20-25 cmH(2) O. Ephedrine or dextran 40% was administered when mean arterial pressure (MAP) was <55 mmHg. Intrathecal morphine, and IV meloxicam and edrophonium were injected before recovery. Time to loss of palpebral reflex (TLPR) upon induction, cardiorespiratory variables, time at first swallowing and other movement, tracheal extubation, vocalisation, spontaneous head lifting (>1 minute), reunion with the ewe, and the number of MAP treatments were recorded. Statistical analysis utilised anova, Mann-Whitney, t-test or Pearsons correlation test as relevant. p < 0.05 was considered significant. RESULTS End-tidal carbon dioxide (mean ± SD) was significantly lower in group S (5.5 ± 0.6 kPa) than in group I (5.8 ± 0.5 kPa) while MAP (70 ± 11 mmHg) and diastolic arterial blood pressure (60 ± 11 mmHg) were higher in group S than in group I (65 ± 12 and 54 ± 11 mmHg, respectively). No differences were found with TLPR and MAP treatments. Time (median, range) from end of anaesthesia to ewe-lamb reunion was briefer (p = 0.018) in group S (48, 20-63 minutes). CONCLUSION Isoflurane and sevoflurane are both suitable for maintaining general anaesthesia in lambs although sevoflurane, as used in this study, allows a more rapid reunion with the ewe. CLINICAL RELEVANCE The principal advantage of sevoflurane over isoflurane during prolonged anaesthesia in lambs is a more rapid recovery.

Investigation of the Relationship Between Transcranial Impedance and Intracranial Pressure

Studies on piglets have shown that cranial bioimpedance (Z) measurements correlate well with invasively measured intracranial pressure (ICP). We have tested the feasibility of collecting transcranial impedance from a clinical device for measuring whole-body water content (ImpediMed SFB7). In the clinical study, 50 normal healthy volunteers had transcranial impedance measured using nine different head montages (forehead to mastoid (left/right), temporal to mastoid (left/right), forehead to temporal (left/right), forehead to occipital (left/right) and temporal to temporal). Impedance was measured 20 times over a frequency range per montage and ANOVA used to test for effects of electrode position upon recorded value. For the experimental study, five sedated and ventilated Marino sheep were instrumented for intraventricular ICP and transcranial impedance measurement. Measures of ICP were recorded while ICP was increased from baseline to greater than 50 mmHg in five steps using an intraventricular infusion of mock CSF. There is a significant effect of electrode position and gender upon transcranial impedance (p < 0.001). The temporal-mastoid electrode position had significantly lower impedance values in keeping with its shorter path length. ICP correlated with craniospinal compliance measurements and Impedance vs Freq by ICP step shows a clear ICP dependence (p = 0.007) across the sheep.

The effects of age, isoflurane and sevoflurane on atracurium in lambs

OBJECTIVE To determine the effects of age, sevoflurane and isoflurane on atracurium-induced neuromuscular blockade in 3-16 week-old lambs. STUDY DESIGN Prospective randomized experimental trial. ANIMALS Twenty-six Scottish blackface ewe-lambs were anaesthetized for spinal surgery when either 3-6 (mean age 4.6 weeks; n = 18) or 12-16 weeks (mean age 13.7 weeks; n = 15) of age; seven animals were anaesthetized at both ages. METHODS After intramuscular injection of medetomidine (10 μg kg(-1)) anaesthesia was induced in the younger lambs either with isoflurane or sevoflurane in oxygen delivered by mask, and in the older lambs with ketamine (4 mg kg(-1)), and midazolam (0.2 mg kg(-1) ) administered intravenously (IV). In both groups anaesthesia was maintained with fixed end-tidal concentrations of either sevoflurane (2.8%) or isoflurane (1.8%) delivered in oxygen. Before surgery meloxicam (0.6 mg kg(-1)), morphine (0.5 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 μg kg(-1) minute(-1) ) were administered IV. The lungs were ventilated mechanically to maintain normocapnia. Neuromuscular block was achieved with a loading dose (LD) of atracurium (0.5 mg kg(-1) IV). The peroneal nerve was stimulated (train-of-four every 12 seconds). Evoked responses in the digital extensor muscles were evaluated by palpation and observation. Maintenance doses (MD) of atracurium (0.17 mg kg(-1) IV) were administered when the first twitch (T1) returned. The onset and duration of LD action (T1 absent) and the duration of MD were recorded. Data were analysed using Students t test, Mann-Whitney U test, repeated-measures anova, Wilcoxons matched pairs test or Pearson correlation coefficient as relevant (p < 0.05). RESULTS Onset of LD action developed significantly (p < 0.05) more rapidly in isoflurane compared with sevoflurane-anaesthetized lambs (55 ± 18 cf. 80 ± 37 seconds). Duration of action of LDs and MDs was longer (p < 0.05) in lambs aged 12-16 than 3-6 weeks (33 ± 5.4 cf. 25 ± 6.4 and 26 ± 4.2 cf. 18 ± 5.5 minutes) but were independent of the anaesthetic used. CONCLUSIONS AND CLINICAL RELEVANCE The effect of atracurium is age-dependent in lambs being prolonged in older animals. The onset of neuromuscular blockade is more rapid in isoflurane compared with sevoflurane-anaesthetized lambs.

An investigation of thrust, depth and the impedance cardiogram as measures of cardiopulmonary resuscitation efficacy in a porcine model of cardiac arrest

OBJECTIVE Optimising the depth and rate of applied chest compressions following out of hospital cardiac arrest is crucial in maintaining end organ perfusion and improving survival. The impedance cardiogram (ICG) measured via defibrillator pads produces a characteristic waveform during chest compressions with the potential to provide feedback on cardiopulmonary resuscitation (CPR) and enhance performance. The objective of this pre-clinical study was to investigate the relationship between mechanical and physiological markers of CPR efficacy in a porcine model and examine the strength of correlation between the ICG amplitude, compression depth and end-tidal CO2 (ETCO2). METHODS Two experiments were performed using 24 swine (12 per experiment). For experiment 1, ventricular fibrillation (VF) was induced and mechanical CPR commenced at varying thrusts (0-60 kg) for 2 min intervals. Chest compression depth was recorded using a Philips QCPR device with additional recording of invasive physiological parameters: systolic blood pressure, ETCO2, cardiac output and carotid flow. For experiment 2, VF was induced and mechanical CPR commenced at varying depths (0-5 cm) for 2 min intervals. The ICG was recorded via defibrillator pads attached to the animals sternum and connected to a Heartsine 500 P defibrillator. ICG amplitude, chest compression depth, systolic blood pressure and ETCO2 were recorded during each cycle. In both experiments the within-animal correlation between the measured parameters was assessed using a mixed effect model. RESULTS In experiment 1 moderate within-animal correlations were observed between physiological parameters and compression depth (r=0.69-0.77) and thrust (r=0.66-0.82). A moderate correlation was observed between compression depth and thrust (r=0.75). In experiment 2 a strong within-animal correlation and moderate overall correlations were observed between ICG amplitude and compression depth (r=0.89, r=0.79) and ETCO2 (r=0.85, r=0.64). CONCLUSION In this porcine model of induced cardiac arrest moderate within animal correlations were observed between mechanical and physiological markers of chest compression efficacy demonstrating the challenge in utilising a single mechanical metric to quantify chest compression efficacy. ICG amplitude demonstrated strong within animal correlations with compression depth and ETCO2 suggesting its potential utility to provide CPR feedback in the out of hospital setting to improve performance.

Genome wide transcriptomic analysis identifies pathways affected by the infusion of Clostridium perfringens culture supernatant in the duodenum of broilers in situ

Clostridium perfringens type A is the main etiological factor for necrotic enteritis, a multifactorial enteric disease that penalizes performance, health, and welfare of poultry. Lack of knowledge of host responses and disease pathogenesis is slowing down progress on developing therapies for disease control. A combined genomewide and targeted gene approach was used to investigate pathways and biological functions affected by the infusion of C. perfringens culture supernatant in the duodenum of broilers in 2 experiments. An in situ isolated loop of duodenum was prepared in anesthetized broilers of 3 wk of age (Exp. 1) and was infused either with crude C. perfringens culture supernatant (n = 7; treated), positive for necrotic enteritis B-like toxin (NetB) as determined by a cytotoxicity assay, or with a control preparation (n = 6; control). Birds were maintained alive for 1 h and then euthanized for tissue recovery. The use of the Affymetrix chicken genome array on RNA samples from loop tissue showed top biological functions affected by culture supernatant infusion included cell morphology, immune cell trafficking, and cell death; pathways affected included death receptor signaling, inflammatory response, and nuclear factor (NF)-κB signaling. In a second in situ study (Exp. 2), broilers were maintained alive for 4 h to monitor temporal expression patterns of targeted genes. Duodenal tissue was removed at 0.5, 1, 2, and 4 h post-infusion with culture supernatant (n = 9) or a control preparation (n = 5) for histology and gene expression analysis. Genes encoding proinflammatory cytokines, such as interferon γ (IFNγ), cell trafficking, such as neuroblastoma 1 (NBL1) and B cell CLL/Lymphoma 6 (BCL6), and cell death, such as Fas cell surface death receptor (FAS) and GTPase IMAP family member 8 (GIMAP8), were differentially expressed in the duodenum of treated and control broilers (P < 0.05). We have demonstrated that C. perfringens culture supernatant (NetB positive) infusion resulted in histological and gene expression changes consistent with necrotic enteritis in the duodenum of broilers. In the absence of live bacteria, crude culture supernatant resulted in early immunomodulation, inflammation, and cell death in the duodenum. The pathways identified here can be targeted for the development of new drugs, vaccines, and novel therapies for necrotic enteritis in broilers.

Translational trial outcomes for capsule endoscopy test devices

Endoscopy and colonoscopy are the clinically recognised standards for imaging and diagnosis of diseases of the gastrointestinal (GI) tract. While scope-based approaches combine optical and ultrasound imaging to allow both imaging of the surface and full thickness of the bowel wall, they are limited in their ability to access the full length of the GI tract particularly the small bowel. Wireless video capsule endoscopy (VCE) devices designed to transit the entire GI tract are currently limited to optical imaging of the superficial surface. Work is thus under way to implement additional capsule endoscopy (CE) functionality through the development of devices incorporating both optical and microultrasound imaging. Research to date has identified several gaps in the literature, which have been addressed through early translational trials in vivo. The areas of concern can be classified by sensing modality and necessary support circuitry, and resulting research questions addressed through bespoke, single system capsules.

148 Paediatric cardiac arrest: is there any myocardial damage in paediatric patients when adult defibrillation energies are administered?

Purpose When attempting defibrillation in an out-of-hospital paediatric patient, the use of a reduced energy is currently recommended in the resuscitation guidelines due to concerns surrounding potential myocardial damage. The purpose of this pilot study was to investigate the 1st shock success of two different automated external defibrillator (AED) energy protocols and observe the resulting levels of myocardial damage in a paediatric model of cardiac arrest. Method A total of six piglets (10–25 kg) were anaesthetised, instrumented and ventricular fibrillation (VF) was electrically induced. After approximately 15 s of untreated VF, a defibrillation shock was delivered using the selected device in line with Protocol A (adult energy doses of 150J) or Protocol B (paediatric energy doses of 75J). Following successful defibrillation, a 3 min recovery period was allowed for the heart to recover before VF was again induced with a maximum of 20 shocks administered. Blood samples were collected at pre-defined time-points whilst the animal was under anaesthesia and analysed for cardiac troponin I (cTnI). After the defibrillation phase of the protocol, the animals remained anaesthetised and vital signs monitored for a period of 6 hours with blood samples collected hourly for further analysis. Results A total of 120 shocks were delivered across both protocols with a 100% shockable rhythm detection and 100% first shock success observed in both Protocol A and B. Prior to the induction of VF, Protocol A and B presented with similar initial mean (±SD) levels of cTnI; 0.04 (±0.03) ng/ml (n=3) and 0.03 (±0.02) ng/ml (n=3), respectively. Comparable results of cTnI were also observed upon completion of the defibrillation phase (Shock 20); Protocol A – 0.12 (±0.05) ng/ml and Protocol B – 0.14 (±0.07) ng/ml. An increase in mean cTnI was detected into the rest period, peaking by 5 hours for both energy protocols. At the 6 hour endpoint of this study, the mean value of cTnI in the blood was reducing for both energy protocols with no statistically significant difference observed between the high and low defibrillation energy groups. Conclusion There was no statistical evidence to suggest that treating the paediatric animals with a higher adult shock energy caused more myocardial damage than a paediatric shock energy. Further investigations are warranted to determine the long term impact on myocardial tissues in a paediatric patient.

Comparison of anaesthesia ‘Day 1 skills’ expectations between veterinary anaesthetists and general practitioners

Day One Skills (DOS) were introduced by the Royal College of Veterinary Surgeons (RCVS) in 2006 as a guideline for minimum skills required by a veterinary graduate. However, the RCVS anaesthesia DOS are broad and do not specify differences in skills required for different species. The aims of this study were: (1) to determine which anaesthesia skills were considered essential for day one practice by UK-based veterinary practitioners (GPs) and anaesthetists; and (2) to explore current opinions on veterinary undergraduate anaesthesia training. Questionnaires for veterinary GPs (QGPs) and veterinary anaesthetists (QVAs) were developed which asked general information on expectations of anaesthesia skills as well as specific expectations for the common veterinary species. Fifty-five UK-based members of the Association of Veterinary Anaesthetists responded, with a random sample of veterinary practices stratified by UK county generating 234 responses and a convenience sample targeted at more specialist veterinary specialities in the UK generating 161 responses. There was close overall agreement between the two groups of GPs and anaesthetists on essential anaesthesia DOS. However, expectations varied with species—greatest in cats and dogs, lowest in exotics. Many respondents commented that new veterinary graduates lack practical skills and should not be expected to be omnicompetent across all species. In conclusion, anaesthesia undergraduate training should prioritise essential practical DOS.

Genome wide transcriptomic analysis identifies pathways affected by the infusion of Clostridium perfringens culture supernatant in the duodenum of broilers in situ1

Clostridium perfringens type A is the main etiological factor for necrotic enteritis, a multifactorial enteric disease that penalizes performance, health, and welfare of poultry. Lack of knowledge of host responses and disease pathogenesis is slowing down progress on developing therapies for disease control. A combined genomewide and targeted gene approach was used to investigate pathways and biological functions affected by the infusion of C. perfringens culture supernatant in the duodenum of broilers in 2 experiments. An in situ isolated loop of duodenum was prepared in anesthetized broilers of 3 wk of age (Exp. 1) and was infused either with crude C. perfringens culture supernatant (n = 7; treated), positive for necrotic enteritis B-like toxin (NetB) as determined by a cytotoxicity assay, or with a control preparation (n = 6; control). Birds were maintained alive for 1 h and then euthanized for tissue recovery. The use of the Affymetrix chicken genome array on RNA samples from loop tissue showed top biological functions affected by culture supernatant infusion included cell morphology, immune cell trafficking, and cell death; pathways affected included death receptor signaling, inflammatory response, and nuclear factor (NF)-κB signaling. In a second in situ study (Exp. 2), broilers were maintained alive for 4 h to monitor temporal expression patterns of targeted genes. Duodenal tissue was removed at 0.5, 1, 2, and 4 h post-infusion with culture supernatant (n = 9) or a control preparation (n = 5) for histology and gene expression analysis. Genes encoding proinflammatory cytokines, such as interferon γ (IFNγ), cell trafficking, such as neuroblastoma 1 (NBL1) and B cell CLL/Lymphoma 6 (BCL6), and cell death, such as Fas cell surface death receptor (FAS) and GTPase IMAP family member 8 (GIMAP8), were differentially expressed in the duodenum of treated and control broilers (P < 0.05). We have demonstrated that C. perfringens culture supernatant (NetB positive) infusion resulted in histological and gene expression changes consistent with necrotic enteritis in the duodenum of broilers. In the absence of live bacteria, crude culture supernatant resulted in early immunomodulation, inflammation, and cell death in the duodenum. The pathways identified here can be targeted for the development of new drugs, vaccines, and novel therapies for necrotic enteritis in broilers.