Time to epileptiform activity and EEG background recovery are independent predictors after cardiac arrest.

OBJECTIVE: Investigate the temporal development of EEG and prognosis. METHODS: Prospective observational substudy of the Target Temperature Management trial. Six sites performed simplified continuous EEG-monitoring (cEEG) on comatose patients after cardiac arrest, blinded to treating physicians. We determined time-points of recovery of a normal-voltage continuous background activity and the appearance of an epileptiform EEG, defined as abundant epileptiform discharges, periodic/rhythmic discharges or electrographic seizure activity. RESULTS: 134 patients were included, 65 had a good outcome. Early recovery of continuous background activity (within 24 h) occurred in 72 patients and predicted good outcome since 55 (76%) had good outcome, increasing the odds for a good outcome seven times compared to a late background recovery. Early appearance of an epileptiform EEG occurred in 38 patients and 34 (89%) had a poor outcome, increasing the odds for a poor outcome six times compared to a late debut. The time to background recovery and the time to epileptiform activity were highly associated with outcome and levels of neuron-specific enolase. Multiple regression analysis showed that both variables were independent predictors. CONCLUSIONS: Time to epileptiform activity and background recovery are independent prognostic indicators. SIGNIFICANCE: Patients with early background recovery combined with late appearance of epileptiform activity may have a good outcome.

A Nordic survey of management practices and owners' attitudes towards keeping horses in groups.

Keeping horses in groups is widely recommended but limited information is available about how this is implemented in practice. The aim of this survey was to describe how horses are kept in the Nordic countries in relation to sex, age, breed, and equestrian discipline and to assess owners' attitudes toward keeping horses in groups. Horse owners in Denmark, Finland, Norway, and Sweden were approached using a web-based questionnaire, which was translated into 4 languages and distributed online via equestrian forums, organizations, and social media. The number of respondents was 3,229, taking care of 17,248 horses. Only 8% of horses were never kept in groups, 47% were permanently grouped for 24 h/d, and 45% were stabled singly but grouped during turnout. Yearlings were most often permanently kept in groups (75%), mares and geldings more commonly during parts of the day (50 and 51%, respectively), and stallions were often kept alone (38%). Icelandic horses were more likely to be permanently kept in groups (36%) than warmbloods (16%) and ponies (15%). Twice as many competition horses (51%) were never grouped compared with horses used for breeding (20%) or leisure purposes (15%). The majority of respondents (86%) strongly agreed that group housing benefits horse welfare and that it is important for horses to have the company of conspecifics (92%). Nevertheless, not all horses were kept in groups, showing that attitudes toward group housing may not necessarily reflect current management. The risk of injury was a concern of many respondents (45%), as was introducing unfamiliar horses into already established groups (40%) and challenges in relation to feeding in groups (44%). Safety of people (23%) and difficulties handling group-kept horses (19%) were regarded as less problematic. Results suggest that the majority of horses have the possibility to freely interact with other horses, either as fulltime members of a group during 24 h/d or during turnout. Future research should address the extent to which being a part-time member of a group affects horse welfare. For permanent group housing to become more widespread, such as it is the case for most farm animals, future research could focus on solving some of the reoccurring problems perceived with keeping horses in groups. The dissemination of evidence-based information on all aspects around keeping horses in groups can ultimately stimulate further positive changes in the management of group-kept horses.

The median preoptic nucleus: front and centre for the regulation of body fluid, sodium, temperature, sleep and cardiovascular homeostasis.

Located in the midline anterior wall of the third cerebral ventricle (i.e. the lamina terminalis), the median preoptic nucleus (MnPO) receives a unique set of afferent neural inputs from fore-, mid- and hindbrain. These afferent connections enable it to receive neural signals related to several important aspects of homeostasis. Included in these afferent projections are (i) neural inputs from two adjacent circumventricular organs, the subfornical organ and organum vasculosum laminae terminalis, that respond to hypertonicity, circulating angiotensin II or other humoural factors, (ii) signals from cutaneous warm and cold receptors that are relayed to MnPO, respectively, via different subnuclei in the lateral parabrachial nucleus and (iii) input from the medulla associated with baroreceptor and vagal afferents. These afferent signals reach appropriate neurones within the MnPO that enable relevant neural outputs, both excitatory and inhibitory, to be activated or inhibited. The efferent neural pathways that proceed from the MnPO terminate on (i) neuroendocrine cells in the hypothalamic supraoptic and paraventricular nuclei to regulate vasopressin release, while polysynaptic pathways from MnPO to cortical sites may drive thirst and water intake, (ii) thermoregulatory pathways to the dorsomedial hypothalamic nucleus and medullary raphé to regulate shivering, brown adipose tissue and skin vasoconstriction, (iii) parvocellular neurones in the hypothalamic paraventricular nucleus that drive autonomic pathways influencing cardiovascular function. As well, (iv) other efferent pathways from the MnPO to sites in the ventrolateral pre-optic nucleus, perifornical region of the lateral hypothalamic area and midbrain influence sleep mechanisms.

CT-proAVP (copeptin), MR-proANP and Peroxiredoxin 4 after cardiac arrest: release profiles and correlation to outcome.

BACKGROUND: Further characterization of the post-cardiac arrest syndrome (PCAS) is essential to better understand the mechanisms resulting in injury and death. We investigated serial serum concentrations of the stress hormone c-terminal provasopressin (CT-proAVP or copeptin), the cardiac biomarker MR-proANP and a biomarker of oxidation injury, Peroxiredoxin 4 (Prx4) in patients treated with mild hypothermia (MHT) after cardiac arrest, and studied their association to the PCAS and long-term outcome. METHODS: Serum samples from cardiac arrest patients were collected serially: at admission, 2, 6, 12, 24, 36, 48 and 72 h after cardiac arrest. CT-proAVP, MR-proANP and Prx4 concentrations were determined and tested for association with two surrogate markers of PCAS (time to return of spontaneous circulation and circulation-SOFA score) and with cerebral performance category (CPC) at 6 months. Good outcome was defined as CPC 1 to 2. RESULTS: Eighty-four patients were included. CT-proAVP, MR-proANP and Prx4 were early biomarkers with maximum concentrations soon after cardiac arrest and with a significant discriminatory ability between good and poor long-term outcome at most time points. CT-proAVP predicted a poor outcome with the highest accuracy, followed by MR-proANP and Prx4 (area under the receiving operating characteristics curve at 12 h of 0.85, 0.77 and 0.76 respectively). CT-proAVP and MR-proANP showed best correlation to the PCAS. CONCLUSION: In 84 resuscitated patients receiving MHT after cardiac arrest, there is a significant difference in concentrations of CT-proAVP, MR-proANP and Prx4 between patients with good and poor outcome. CT-proAVP and MR-proANP have a significant correlation to surrogate markers of the PCAS.

Continuous evaluation of neurological prognosis after cardiac arrest.

Post-resuscitation care has changed in the last decade, and outcome after cardiac arrest has improved, thanks to several combined measures. Induced hypothermia has shown a treatment benefit in two randomized trials, but some doubts remain. General care has improved, including the use of emergency coronary intervention. Assessment of neurological function and prognosis in comatose cardiac arrest patient is challenging, especially when treated with hypothermia. In this review, we evaluate the recent literature and discuss the available evidence for prognostication after cardiac arrest in the era of temperature management. Relevant literature was identified searching PubMed and reading published papers in the field, but no standardized search strategy was used. The complexity of predicting outcome after cardiac arrest and induced hypothermia is recognized in the literature, and no single test can predict a poor prognosis with absolute certainty. A clinical neurological examination is still the gold standard, but the results need careful interpretation because many patients are affected by sedatives and by hypothermia. Common adjuncts include neurophysiology, brain imaging and biomarkers, and a multimodal strategy is generally recommended. Current guidelines for prediction of outcome after cardiac arrest and induced hypothermia are not sufficient. Based on our expert opinion, we suggest a multimodal approach with a continuous evaluation of prognosis based on repeated neurological examinations and electroencephalography. Somatosensory-evoked potential is an established method to help determine a poor outcome and is recommended, whereas biomarkers and magnetic resonance imaging are promising adjuncts. We recommend that a decisive evaluation of prognosis is performed at 72 h after normothermia or later in a patient free of sedative and analgetic drugs.

Growth, training response and health in Standardbred yearlings fed a forage-only diet.

The aim of this study was to, from a holistic perspective, describe the effects of a forage-only feeding system and a conventional training program on young Standardbred horses and compare data with similar observations from the literature. Sixteen Standardbred colts fed a forage-only diet for 4 months from breaking (August to December) and with the goal to vigorously trot 5 to 7 km at a speed of 5.6 m/s (3 min/km) were studied. The horses were fed grass haylage (56 to 61% dry matter (DM), 2.80 to 3.02 Mcal DE/kg DM and 130 to 152 g CP/kg DM) ad libitum, 1 kg of a lucerne product and minerals. The amount of training and number of training sessions were documented daily, and feed intake and body development were measured once every month. Heart rate (HR) was measured during and after a standardized exercise test in October and December. In December, a postexercise venous blood sample was collected and analyzed for plasma lactate concentration. Muscle biopsies (m. gluteus medius) were taken and analyzed for glycogen and fiber composition. Health was assessed in October and November by an independent veterinarian using a standardized health scoring protocol. BW and height at withers increased from 402 to 453 kg (root mean square error (RMSE) 6) and from 148.7 to 154.1 cm (RMSE 0.7), respectively, and the body condition score was 4.9 (RMSE 0.2) at the end of the study. Muscle glycogen content was 532 mmol/kg dry weight (s.d. 56). There was a significant decrease in postexercise HR (81 v. 73 bpm, RMSE 8), and the individual amount of training was negatively correlated with HR during and after exercise. Health scores were high and similar at both assessments (8.4 and 8.4 (RMSE 1.0) out of 10; P > 0.05), and the number of lost training days per month due to health problems was <0.9, with the exception of November (5.3 days). It is concluded that yearlings in training fed high-energy forage ad libitum can reach a conventional training goal and grow at least as well as earlier observations on yearlings of other light breeds.

Gut microcirculatory and mitochondrial effects of hyperdynamic endotoxaemic shock and norepinephrine treatment.

BACKGROUND: Microcirculatory and mitochondrial dysfunction are important factors in the development of septic shock. In this study, we investigated the effects of fluid resuscitated endotoxaemic shock and norepinephrine treatment on intestinal microcirculation and mitochondrial function in sheep. METHODS: Eight anaesthetized sheep received an i.v. infusion of endotoxin. After 24 h, mean arterial pressure (MAP) was restored to baseline levels with a norepinephrine infusion. Five sheep served as sham experiments. Central and regional haemodynamics were monitored, and ileal microcirculation was evaluated with laser Doppler and sidestream dark-field videomicroscopy techniques. Gut mucosal acidosis was assessed by air tonometry, and ileal wall biopsies were analysed for mitochondrial activity. RESULTS: After 24 h of endotoxaemia, the animals had developed hyperdynamic shock with systemic and mucosal acidosis. Although superior mesenteric artery (SMA) flow was higher than the baseline values, ileal microcirculatory perfusion and mitochondrial complex I activity decreased. After norepinephrine was started, SMA flow, ileal microcirculation, and mucosal acidosis remained unchanged. Although no statistically significant difference could be demonstrated, norepinephrine increased mitochondrial complex I activity in five of the six animals from which ileal biopsies were taken. CONCLUSIONS: Although fluid resuscitated endotoxaemic shock increased regional blood flow, microcirculatory and mitochondrial alterations were still present. Restoring MAP with norepinephrine did not affect ileal microcirculation or mucosal acidosis, indicating that perfusion pressure manipulation is of limited importance to the intestinal microcirculation in established endotoxaemic shock.

Neuron-specific enolase correlates with other prognostic markers after cardiac arrest.

OBJECTIVE: Therapeutic hypothermia (TH) is a recommended treatment for survivors of cardiac arrest. Prognostication is complicated since sedation and muscle relaxation are used and established indicators of a poor prognosis are lacking. This prospective, observational study describes the pattern of commonly used prognostic markers in a hypothermia-treated cohort of cardiac arrest patients with prolonged coma. METHODS: Among 111 consecutive patients, 19 died, 58 recovered, and 34 were in coma 3 days after normothermia (4.5 days after cardiac arrest), defined as prolonged coma. All patients were monitored with continuous amplitude-integrated EEG and repeated samples of neuron-specific enolase (NSE) were collected. In patients with prolonged coma, somatosensory evoked potentials (SSEP) and brain MRI were performed. A postmortem brain investigation was undertaken in patients who died. RESULTS: Six of the 17 patients (35%) with NSE levels <33 µg/L at 48 hours regained the capacity to obey verbal commands. By contrast, all 17 patients with NSE levels >33 failed to recover consciousness. In the >33 NSE group, all 10 studied with MRI had extensive brain injury on diffusion-weighted images, 12/16 lacked cortical responses on SSEP, and all 6 who underwent autopsy had extensive severe histologic damage. NSE levels also correlated with EEG pattern, but less uniformly, since 11/17 with NSE <33 had an electrographic status epilepticus (ESE), only one of whom recovered. A continuous EEG pattern correlated to NSE <33 and awakening. CONCLUSIONS: NSE correlates well with other markers of ischemic brain injury. In patients with no other signs of brain injury, postanoxic ESE may explain a poor outcome.

The effects of isoflurane anesthesia and mechanical ventilation on renal function during endotoxemia.

BACKGROUND: Isoflurane is a common anesthetic agent used in human surgery and in animal models of sepsis. It has been suggested to have beneficial anti-inflammatory properties and to protect kidney function. Here, we investigated the effect of isoflurane on the development of kidney injury and dysfunction during 48-h endotoxemia in sheep. METHODS: Before the experiments, the sheep (n=16) were surgically equipped with transit-time flowprobes around the renal, femoral and superior mesenteric artery. The animals were randomized to either be anesthetized with isoflurane and mechanically ventilated or to remain conscious while they received intravenous Escherichia coli lipopolysaccharide (LPS) for 48 h (25 ng/kg/min). In two animals in each group, the LPS was excluded to investigate any effect of isoflurane per se over time. RESULTS: Endotoxemia caused cardiovascular changes typical for hyperdynamic sepsis and, although renal hyperemia occurred, impaired renal function in both groups. Compared with conscious animals, isoflurane significantly (P<0.05) reduced urine output, renal creatinine clearance, fractional sodium excretion and renal blood flow during endotoxemia. Furthermore, the plasma concentrations of urea and creatinine increased more in the anesthetized animals. Isoflurane anesthesia also enhanced neutrophil activity and accumulation in the kidney during endotoxemia. N-acetyl-ß-D-glucosaminidase was significantly increased, with no inter-group difference as an indication of tubular injury. CONCLUSIONS: The results of the current study suggest that isoflurane anesthesia (minimum alveolar concentration 1.0) with mechanical ventilation aggravates renal dysfunction during 48 h of endotoxemia and does not significantly reduce the inflammatory response or signs of tubular damage.

An evaluation of monitoring possibilities of argatroban using rotational thromboelastometry and activated partial thromboplastin time.

BACKGROUND: Rotational thrombelastometry/thrombelastography with ROTEM and TEG is becoming available bedside in an increasing number of intensive care units, where many patients with heparin-induced thrombocytopenia (HIT) are treated. The study has been performed in an effort to find out whether ROTEM could be an alternative to activated partial thromboplastin time (aPTT) when argatroban is used for anticoagulation. METHODS: Argatroban was added in vitro to a series of citrated whole-blood samples from 10 healthy volunteers to obtain whole-blood concentrations of 0, 0.125, 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 mg/l. ROTEM and whole-blood aPTT analyses were performed at each argatroban concentration. Correlation analyses were performed using the Spearman correlation analysis. RESULTS: There was a significant and strong correlation between argatroban concentrations and clotting time (CT in ROTEM analysis with INTEM) (P<0.0001 and r=0.98). Also, the ROTEM time to maximum clot formation velocity (MAXV-t) appeared to have a very strong and highly significant correlation to argatroban concentrations (P<0.0001 and r=0.95). When we studied the correlation between aPTT and CT, we found a highly significant and strong correlation between these two analyses (P<0.0001 and r=0.97), especially so in the clinically relevant therapeutic range up to 100 s aPTT prolongation for HIT patients. CONCLUSION: A significant and strong correlation was found between argatroban concentrations and several ROTEM parameters. Rotational thrombelastometry/thrombelastography has a potential role in increasing the safety of argatroban anticoagulation in critically ill patients.

Hyponatremia complicating labour--rare or unrecognised? A prospective observational study.

OBJECTIVE: The aim of this study was to investigate the occurrence of hyponatraemia following delivery, with a hypothesis that hyponatraemia has a high prevalence in labouring women. DESIGN: Prospective observational study. SETTING: Consultant-led delivery suite in County Hospital, Kalmar, Sweden. SAMPLE: A total of 287 pregnant women at term (37 full gestational weeks). METHODS: Oral fluids were allowed during labour. Blood samples were collected on admission, after delivery, and from the umbilical artery and vein. MAIN OUTCOME MEASURE: Hyponatraemia defined as plasma sodium < or =130 mmol/l after delivery. RESULTS: Hyponatraemia was found in 16 (26%) of the 61 mothers who received more than 2500 ml of fluid during labour. Two-thirds of fluids were orally ingested. Decrease in plasma sodium concentration during labour correlated with duration of labour and the total fluid volume administered. Analysis by multivariate logistic regression showed that hyponatraemia was significantly correlated with fluid volume (P < 0.001) but not with oxytocin administration or epidural analgesia. Hyponatraemia correlated significantly with prolonged second stage of labour, instrumental delivery, and emergency caesarean section for failure to progress (P = 0.002). CONCLUSIONS: Hyponatraemia is not uncommon following labour. Tolerance to a water load is diminished during labour; therefore, even moderate fluid volumes may cause hyponatraemia. Women should not be encouraged to drink excessively during labour. Oral fluids, when permitted, should be recorded, and intravenous administration of hypotonic fluids should be avoided. When abundant drinking is unrecognised or intravenous fluid administration liberal, life-threatening hyponatraemia may develop. The possibility that hyponatraemia may influence uterine contractility merits further investigation.

Central inhibition of opioid receptor subtypes and its effect on haemorrhagic hypotension in conscious sheep.

AIM: To investigate the contribution of cerebral mu-, kappa- and delta-opioid receptors in causing the hypotension, bradycardia and renal hypoperfusion evoked by haemorrhage. METHODS: Adult conscious ewes were bled continuously from a jugular vein until mean arterial blood pressure (MAP) was reduced to below 50 mmHg. Starting 30 min before and continuing until 60 min after haemorrhage either artificial cerebrospinal fluid (control), d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP micro-receptor antagonist), ICI 174,864 (delta-receptor antagonist) or nor-binaltorphimine dihydrochloride (nor-BNI, kappa-receptor antagonist) were infused intracerebroventricularly. In a randomized crossover fashion the effect of antagonizing one central opioid receptor subtype was compared to control experiments in the same animal (n = 6 in all groups). RESULTS: Compared to corresponding controls, nor-BNI and ICI 174,864 significantly increased the haemorrhage volume needed to reduce MAP to below 50 mmHg (+4.7 mL kg(-1), SD 1.8 and +3.1 mL kg(-1), SD 3.0 respectively). In the nor-BNI group this was accompanied by a significantly augmented tachycardia before MAP fell. Both nor-BNI and ICI 174,864 also postponed haemorrhagic bradycardia and prolonged adequate blood flow to the kidney. The infusions did not affect the circulation per se or the recovery after haemorrhage. The micro-opioid receptor blockade had no effect on baseline circulation or the response to haemorrhage. CONCLUSION: Activation of kappa- and delta-opioid receptors adjacent to the ventricular compartment contributes to initiating haemorrhagic hypotension and bradycardia in conscious sheep. However, other parts of the brain and different receptors are likely to play a role as well.

Training methods for horses: habituation to a frightening stimulus.

REASONS FOR PERFORMING STUDY: Responses of horses in frightening situations are important for both equine and human safety. Considerable scientific interest has been shown in development of reactivity tests, but little effort has been dedicated to the development of appropriate training methods for reducing fearfulness. OBJECTIVES: To investigate which of 3 different training methods (habituation, desensitisation and counter-conditioning) was most effective in teaching horses to react calmly in a potentially frightening situation. HYPOTHESES: 1) Horses are able to generalise about the test stimulus such that, once familiar with the test stimulus in one situation, it appears less frightening and elicits a reduced response even when the stimulus intensity is increased or the stimulus is presented differently; and 2) alternative methods such as desensitisation and counter-conditioning would be more efficient than a classic habituation approach. METHODS: Twenty-seven naive 2-year-old Danish Warmblood stallions were trained according to 3 different methods, based on classical learning theory: 1) horses (n = 9) were exposed to the full stimulus (a moving, white nylon bag, 1.2 x 0.75 m) in 5 daily training sessions until they met a predefined habituation criterion (habituation); 2) horses (n = 9) were introduced gradually to the stimulus and habituated to each step before the full stimulus was applied (desensitisation); 3) horses (n = 9) were trained to associate the stimulus with a positive reward before being exposed to the full stimulus (counter-conditioning). Each horse received 5 training sessions of 3 min per day. Heart rate and behavioural responses were recorded. RESULTS: Horses trained with the desensitisation method showed fewer flight responses in total and needed fewer training sessions to learn to react calmly to test stimuli. Variations in heart rate persisted even when behavioural responses had ceased. In addition, all horses on the desensitisation method eventually habituated to the test stimulus whereas some horses on the other methods did not. CONCLUSIONS AND POTENTIAL RELEVANCE: Desensitisation appeared to be the most effective training method for horses in frightening situations. Further research is needed in order to investigate the role of positive reinforcement, such as offering food, in the training of horses.

Activation of central opioid receptors determines the timing of hypotension during acute hemorrhage-induced hypovolemia in conscious sheep.

After an initial compensatory phase, hemorrhage reduces blood pressure due to a widespread reduction of sympathetic nerve activity (decompensatory phase). Here, we investigate the influence of intracerebroventricular naloxone (opioid-receptor antagonist) and morphine (opioid-receptor agonist) on the two phases of hemorrhage, central and peripheral hemodynamics, and release of vasopressin and renin in chronically instrumented conscious sheep. Adult ewes were bled (0.7 ml x kg(-1) x min(-1)) from a jugular vein until mean arterial blood pressure (MAP) reached 50 mmHg. Starting 30 min before and continuing until 60 min after hemorrhage, either artificial cerebrospinal fluid (aCSF), naloxone, or morphine was infused intracerebroventricularly. Naloxone (200 microg/min but not 20 or 2.0 microg/min) significantly increased the hemorrhage volume compared with aCSF (19.5 +/- 3.2 vs. 13.9 +/- 1.1 ml/kg). Naloxone also increased heart rate and cardiac index. Morphine (2.0 microg/min) increased femoral blood flow and decreased hemorrhage volume needed to reduce MAP to 50 mmHg (8.9 +/- 1.5 vs. 13.9 +/- 1.1 ml/kg). The effects of morphine were abolished by naloxone at 20 microg/min. It is concluded that the commencement of the decompensatory phase of hemorrhage in conscious sheep involves endogenous activation of central opioid receptors. The effective dose of morphine most likely activated mu-opioid receptors, but they appear not to have been responsible for initiating decompensation as 1) naloxone only inhibited an endogenous mechanism at a dose much higher than the effective dose of morphine, and 2) the effects of morphine were blocked by a dose of naloxone, which, by itself, did not delay the decompensatory phase.

Circulatory effects of angiotensin II during anaesthesia, evaluated by real-time spectral analysis.

BACKGROUND: General anaesthesia may stimulate the renin-angiotensin system. Exogenous administration of angiotensin II elevates blood pressure mainly via increased total peripheral resistance caused by direct vasoconstrictor actions. It is also well established that the hypertensive effect of angiotensin II involves a cerebrally mediated component. The hypertensive effect of an intravascular infusion of angiotensin II is substantially reduced by isoflurane anaesthesia. A likely mechanism is that isoflurane anaesthesia reduces the cerebral component of the angiotensin II effect on blood pressure, which involves influences on autonomic nervous activity. In an experimental study in sheep we used real-time spectral analysis of arterial blood pressure signals to obtain information on parasympathetic, respectively, sympathetic autonomic nervous activity in response to angiotensin II administration during isoflurane anaesthesia. METHODS: The study was performed on conscious and isoflurane-anaesthetized sheep that were subjected to an intracarotid infusion of angiotensin II (85 ng kg(-1) min(-1)) during 20 min followed by a recovery period of 30 min and thereafter an injection of the angiotensin II, AT1-receptor antagonist losartan (10 mg kg(-1)) i.v. Systemic and regional (renal and femoral) circulation was monitored in parallel to real-time spectral analysis of the arterial blood pressure signal. RESULTS: Isoflurane anaesthesia reduced both magnitude and duration of the hypertensive response to angiotensin II infusion. The power spectral density in the frequency band that represents sympathetic activation, correlated to the changes in mean arterial pressure in conscious animals, but not during isoflurane anaesthesia. CONCLUSION: We conclude that the cerebrally mediated component of the hypertensive effect of circulating angiotensin II is largely eliminated by isoflurane anaesthesia. Spectral power analysis of the blood pressure signal indicates that the cerebral angiotensin II effect involves activation of sympathetic nervous activity.

Responses of horses in behavioural tests correlate with temperament assessed by riders.

REASONS FOR PERFORMING STUDY: Behavioural tests as well as observers' ratings have been used to study horses' temperament. However, the relationship between the ratings and the responses in behavioural tests has not yet been studied in detail. OBJECTIVES: The aim of the present study was to examine this relationship between ratings and responses. METHODS: Eighteen mature Swedish Warmblood horses were subjected to 2 behavioural tests, one relating to novelty (novel object test) and one to handling (handling test). Subsequently, 16 of these horses were ridden by 16 equally experienced students, having no former experience with the horses. Immediately after each ride, the students scored the horse for 10 temperamental traits using a line rating method. RESULTS: It was shown that for each temperamental trait all 16 riders agreed on the ranking of the horses (0.212

Losartan increases renal blood flow during isoflurane anesthesia in sheep.

BACKGROUND: Inhaled anesthetics cause a transient reversible depression of renal function by direct renal effects or indirectly by changes in neurohumoral systems or cardiovascular performance. When the sympathetic nervous activity is decreased during anesthesia, other vasoactive systems like vasopressin (AVP) and particularly the renin angiotensin system (RAS) are of importance for blood pressure maintenance. Little is known about how the renal circulation is affected by angiotensin receptor blockade during isoflurane anesthesia. METHODS: The study was performed on isoflurane anesthetized sheep equipped with flow probes (placed around a femoral and a renal artery) and a pulmonary artery catheter. During stable conditions the sheep were given one or more of the following substances: isotonic saline (NaCl); losartan (LOS) 10 mg x kg(-1); prazosin (PRAZ) 0.2 mg x kg(-1) and a vasopressin V1-receptor antagonist (AVP-a) 10 microg x kg(-1). RESULTS: LOS and AVP-a did not affect mean arterial pressure (MAP), whereas PRAZ lowered MAP significantly (from 98+/-12 to 65+/-7 mmHg). Renal blood flow (RBF) increased after LOS treatment (148+/-34 to 222+/-33 ml x min(-1)). The other substances were without effect on RBF. Femoral blood flow remained unchanged after all treatments. CONCLUSION: We conclude that the sympathoadrenal system is still the major determinant for blood pressure maintenance during isoflurane anesthesia in sheep. The apparently increased activity of the renin angiotensin system in this situation causes a reduction in renal blood flow, which is counteracted by angiotensin II AT1-receptor blockade.

Demographic data of a population of insured Swedish dogs measured in a questionnaire study.

Dogs, in the age range 1-3 years old, were randomly selected from the largest animal insurance database in Sweden for inclusion in the study. The study was performed in 1997, and a total of 680 dog owners were selected for the study. A total of 461 dog owners completed the survey, at an overall response rate of 68%. Data was compared to a recent gallup performed on a sample of all dogs in Sweden. The demographic statistics of the insured dog population were in many aspects similar to the total dog population of Sweden. Typical for both insured dogs and the total population of dogs were a low proportion of neutered dogs, that many dogs were bought at an early age, that many dogs were in contact with a "breeder" when sold, and a similar profile of health status. However, "dog breeders" seemed to have their dogs insured to a higher extent than the general dog owner. It was concluded that as the populations were alike in many respects, it is reasonable to use the insurance database for epidemiological studies on diet and exercise in Swedish dogs.