The role of branchial and orobranchial O-2 chemoreceptors in the control of aquatic surface respiration in the neotropical fish tambaqui (Colossoma macropomum): progressive responses to prolonged hypoxia

The present study examined the role of branchial and orobranchial O-2 chemoreceptors in the cardiorespiratory responses, aquatic surface respiration (ASR), and the development of inferior lip swelling in tambaqui during prolonged (6 h) exposure to hypoxia. Intact fish (control) and three groups of denervated fish (bilateral denervation of cranial nerves IX+X (to the gills), of cranial nerves V+VII (to the orobranchial cavity) or of cranial nerves V alone), were exposed to severe hypoxia (Pw(O2) = 10 mmHg) for 360 min. Respiratory frequency (fR) and heart rate (fH) were recorded simultaneously with ASR. Intact (control) fish increased fR, ventilation amplitude (V-AMP) and developed hypoxic bradycardia in the first 60 min of hypoxia. The bradycardia, however, abated progressively and had returned to normoxic levels by the last hour of exposure to hypoxia. The changes in respiratory frequency and the hypoxic bradycardia were eliminated by denervation of cranial nerves IX and X but were not affected by denervation of cranial nerves V or V+VII. The VAMP was not abolished by the various denervation protocols. The fH in fish with denervation of cranial nerves V or V+VII, however, did not recover to control values as in intact fish. After 360 min of exposure to hypoxia only the intact and IX+X denervated fish performed ASR. Denervation of cranial nerve V abolished the ASR behavior. However, all (control and denervated (IX+X, V and V+VII) fish developed inferior lip swelling. These results indicate that ASR is triggered by O-2 chemoreceptors innervated by cranial nerve V but that other mechanisms, such as a direct effect of hypoxia on the lip tissue, trigger lip swelling.

Vagal control of heart rate and cardiac shunts in reptiles: Relation to metabolic state

The vagus is clearly of primary importance in the regulation of reptilian cardiorespiratory systems. Vagal control of pulmonary blood flow and cardiac shunts provides reptiles with an additional means of regulating arterial oxygen levels that is not present in endothermic vertebrates (birds and mammals). Within a given species, there exists a clear correlation between withdrawal of vagal tone on the cardiovascular system and elevated metabolic rate. Undisturbed and resting reptiles are normally characterised by high vagal tone, low pulmonary blood flow and large right-left (R-L) cardiac shunts. The low oxygen levels that result from the large R-L shunt may serve to regulate metabolism. However, when metabolism is increased by temperature, exercise or digestion, the R-L cardiac shunt is reduced, which serves to increase oxygen delivery. This response is partially elicit ed by reduction of vagal tone. Interspecies comparisons reveal a similar pattern. Thus, species that are able to sustain the highest metabolic rates possess the highest degree of anatomical ventricular separation and, therefore, less cardiac shunting. It is interesting to note that when cardiac shunts occur in mammals, due for example to developmental defects, they are associated with reduced maximal metabolic rates and impaired exercise tolerance. It appears, therefore, that full separation of ventricular blood flows was a prerequisite for the evolution of high aerobic metabolic rates and exercise stamina in mammals and birds.

Chest associated to motor physiotherapy acutely improves oxygen saturation, heart rate and respiratory rate in premature newborns with periventricular-intraventricular hemorrhage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative study of epidural xylazine or clonidine in horses

Objective To evaluate the cardiorespiratory and behavioural effects of epidural xylazine (XYL) or clonidine (CLO) in horses.Study design Blinded, randomized experimental study.Twelve healthy Arabian yearling horses weighing 117-204 kg were randomly allocated into two groups: XYL (n = 6) and CLO (n = 6).Methods An epidural catheter was inserted and a facial arterial catheter was placed and the next day the horses were restrained in stocks. Baseline values for heart (HR) and respiratory (RR) rates, arterial pressure and behavioural responses were evaluated before (TO) and 10, 20, 30, 45, 60, 90 and 120 minutes after epidural injection (T10-T120). The horses received 0.2 mg kg(-1) of XYL or 5 mu g kg(-1) CLO; adjusted to (3.4 + (body weight in kg x 0.013) mL with saline. Data were analysed by the Kolmogorov-Smirnov test, one-way ANOVA with repeated measures, and one-way ANOVA followed by a Student-Newman-Keuls test or Fisher's exact test, as necessary. Significance was set at p <= 0.05.Results Sedation and ataxia were seen at T10, persisting until T120 in four and three horses, respectively, in XYL and all horses in CLO respectively. Two XYL and one CLO horses became recumbent at T45 and T25 respectively. Penile prolapse occurred in four of five males at T30 and T45, in the XYL and CLO groups, respectively, resolving by T120. Tail relaxation was present from T10 to T120 in all horses in XYL and in four horses in CLO. Head drop was observed from T20 to T60 and from T10 to T120 in XYL and CLO respectively. Respiratory rate decreased significantly only at T45 in the CLO group. Heart rate and arterial blood pressure remained stable.Conclusions and clinical relevance Epidural CLO and XYL produce similar cardiorespiratory and behavioural changes but neither would be safe to use clinically at the doses used in this study.

Anaerobic threshold estimation by statistical modelling.

Anaerobic threshold (AT) is usually estimated as a change point problem by visual analysis of the cardiorespiratory response to incremental dynamic exercise. In this study, two phase linear (TPL) models of the linear-linear and linear-quadratic type were used for the estimation of AT. The correlation coefficient between the classical and statistical approaches was 0.88, and 0.89 after outlier exclusion. The TPL models provide a simple method for estimating AT that can be easily implemented using a digital computer for the automatic pattern recognition of AT.

Pituitary-adrenal activity and opioid release in ponies during thiopentone/halothane anaesthesia

The effect of thiopentone/halothane anaesthesia on the release of endogenous opioid, adrenocorticotrophin, arginine vasopressin, cortisol and catecholamine was investigated in ponies. The contribution made by halothane itself was studied by maintaining six ponies with a constant 12 per cent end tidal halothane concentration and five with a concentration ranging between 0.8 and 12 per cent. Cardiorespiratory depression was more prolonged in the ponies receiving a constant 1-2 per cent end tidal halothane concentration than in those which received less halothane. Plasma lactate concentration increased and haematocrit decreased during halothane anaesthesia. The concentrations of met-enkephalin, dynorphin and catecholamines did not change and those of β-endorphin, adrenocorticotrophin, arginine vasopressin and cortisol increased during halothane anaesthesia. Halothane appeared to be a major stimulus to pituitary adrenocortical activation because the adrenocortical secretion was proportional to the amount of halothane inhaled. β-endorphin increased proportionally more than adrenocorticotrophin and their plasma concentrations were not correlated, suggesting that they have independent secretion mechanisms.

Total intravenous anaesthesia in ponies using detomidine, ketamine and guaiphenesin: Pharmacokinetics, cardiopulmonary and endocrine effects

Pharmacokinetics and some pharmacological effects of anaesthesia induced by a combination of detomidine, ketamine and guaiphenesin were investigated in eight ponies. Cardiopulmonary function was studied and plasma met-enkephalin, dynorphin, β-endorphin; arginine vasopressin, adrenocorticotrophin, cortisol, 11-deoxycortisol and catecholamine concentrations were measured. The combination produced slight cardiorespiratory depression, hyperglycaemia and a reduction in haematocrit. There were no changes in plasma opioids, pituitary peptides or catecholamines. Plasma cortisol concentration decreased and plasma 11-deoxycortisol increased indicating a suppression of steroidogenesis. Steady state ketamine and guaiphenesin concentrations were attained during the infusion period, and ketamine concentrations likely to provide adequate analgesia for surgical operations were achieved (more than 2.2 μg ml-1). Steady state detomidine concentration was not attained. The ponies took on average 68 minutes to recover to standing and the recovery was uneventful.

Endocrine changes in cerebrospinal fluid, pituitary effluent, and peripheral plasma of anesthetized ponies

Objective - To investigate the effects of inhalation and total IV anesthesia on pituitary-adrenal activity in ponies. Animals - 9 healthy ponies: 5 geldings and 4 mares. Procedure - Catheters were placed in the cavernous sinus below the pituitary gland and in the subarachnoid space via the lumbosacral space. After 72 hours, administration of acepromazine was followed by induction of anesthesia with thiopentone and maintenance with halothane (halothane protocol), or for the IV protocol, anesthesia induction with detomidine and ketamine was followed by maintenance with IV infusion of a detomidine-ketamine-guaifenesin combination. Arterial blood pressure and gas tensions were measured throughout anesthesia. Peptide and catecholamine concentrations were measured in pituitary effluent, peripheral plasma, and CSF. Peripheral plasma cortisol, glucose, and lactate concentrations also were measured. Results - Intravenous anesthesia caused less cardiorespiratory depression than did halothane. ACTH, metenkephalin, arginine vasopressin, and norepinephrine pituitary effluent and peripheral plasma concentrations were higher during halothane anesthesia, with little change during intravenous anesthesia. Pituitary effluent plasma β-endorphin and peripheral plasma cortisol concentrations increased during halothane anesthesia only. Dynorphin concentrations did not change in either group. Hyperglycemia developed during intravenous anesthesia only Minimal changes occurred in CSF hormonal concentrations during anesthesia. Conclusion - The pituitary gland has a major role in maintaining circulating peptides during anesthesia. Compared with halothane, IV anesthesia appeared to suppress pituitary secretion.

Efeito da posição do prematuro no desmame da ventilação mecânica

Objective: the purpose of this study was to determine the effects of prone positioning on cardiorespiratory stability and weaning outcome of preterm infants during weaning from mechanical ventilation. Methods: from January to December 1999, a sample of 42 preterm infants, with birthweight < 2,000 g, mechanically ventilated in the first week of life, were randomly divided, in the beginning of the weaning process, in two groups according to the position: supine position (n = 21) or prone position (n = 21). Heart rate, respiratory rate, transcutaneous oxygen saturation and ventilatory parameters were recorded every one hour. Length of the weaning process and complications were also assessed. Results: in both groups the mean gestational age was 29 weeks, most of the patients presented very low birthweight and respiratory distress syndrome. The mean length of the weaning process was 2 days. There were no differences between the groups regarding respiratory rate, heart rate and transcutaneous oxygen saturation, however, oxygen desaturation episodes were more frequent in supine position (p = 0.009). Ventilatory parameters decreased faster and reintubation was less frequent in the prone group (4% versus 33%). No adverse effects of prone positioning were observed. Conclusion: these results suggest that prone position is a safe and beneficial procedure during the weaning from mechanical ventilation and may contribute to weaning success in preterm infants.

The comparative efficacy of yohimbine and atipamezole to treat amitraz intoxication in dogs

This study compared the efficacy of yohimbine with atipamezole, a new α2-adrenergic antagonist, to treat canine amitraz intoxication. Thirty dogs were divided equally into 3 groups (A, AY, and AA). Group A received 2.5% amitraz iv at 1 mg/kg; Group AY received the same dose of amitraz followed 30 min later by 0.1 mg/kg (2 mg/mL) yohimbine iv; and Group AA received the same dose of amitraz followed 30 min later by 0.2 mg/kg (5 mg/mL) atipamezole iv. Temperature, heart rate, respiratory frequency, mean arterial pressure, degree of sedation, mean time of tranquilization and diameter of pupils were monitored for 360 min. Sedation, logs of reflexes, hypothermia bradycardia, hypotension, bradypnea and mydriasis were observed in Group A, with 3rd eyelid prolapse, increased diuresis and vomiting in some animals. Yohimbine reversed all alterations induced by amitraz, but induced significant cardiorespiratory effects such as tachycardia and tachypnea. Atipamezole was a useful antagonist for amitraz, with less cardiorespiratory effects, suggesting its potential role as an alternative treatment of amitraz intoxication in dogs.

Mensuração da energia despendida no jejum e no aporte calórico (MEL) em parturientes

This research aims to measure the energy spending in parturient women of low gestation risk. Participants were selected randomly and submitted to fasting (n=15; Group I) or honey ingestion (n = 15; Group II). Data were collected by means of capillary blood values and heart frequency monitoring. The paired t-test with a 5% significance level and Tukey's method were used in statistical analysis. The results showed that honey ingestion did not promote an overload in the mother's glucose; the lactate response demonstrated that the substrate offered was well used; the cardiorespiratory rate demonstrated good performance for both groups; the total energy spent during labor demonstrated that carbohydrate ingestion exerts significant influence, improving maternal anaerobic performance; the group which remained in fasting presented, immediately after labor, higher levels of lactate, showing the organism's efforts to compensate for the energy spent.

Respiratory chemoreceptor function in vertebrates - Comparative and evolutionary aspects

The sensing of blood gas tensions and/or pH is an evolutionarily conserved, homeostatic mechanism, observable in almost all species studied from invertebrates to man. In vertebrates, a shift from the peripheral O2-oriented sensing in fish, to the central CO2/pH sensing in most tetrapods reflects the specific behavioral requirements of these two groups whereby, in teleost fish, a highly O2-oriented control of breathing matches the ever-changing and low oxygen levels in water, whilst the transition to air-breathing increased the importance of acid-base regulation and O2-related drive, although retained, became relatively less important. The South American lungfish and tetrapods are probably sister groups, a conclusion backed up by many similar features of respiratory control. For example, the relative roles of peripheral and central chemoreceptors are present both in the lungfish and in land vertebrates. In both groups, the central CO2/pH receptors dominate the ventilatory response to hypercarbia (60-80), while the peripheral CO2/pH receptors account for 20-30. Some basic components of respiratory control have changed little during evolution. This review presents studies that reflect the current trends in the field of chemoreceptor function, and several laboratories are involved. An exhaustive review on the previous literature, however, is beyond the intended scope of the article. Rather, we present examples of current trends in respiratory function in vertebrates, ranging from fish to humans, and focus on both O2 sensing and CO2 sensing. As well, we consider the impact of chronic levels of hypoxia - a physiological condition in fish and in land vertebrates resident at high elevations or suffering from one of the many cardiorespiratory disease states that predispose an animal to impaired ventilation or cardiac output. This provides a basis for a comparative physiology that is informative about the evolution of respiratory functions in vertebrates and about human disease. Currently, most detail is known for mammals, for which molecular biology and respiratory physiology have combined in the discovery of the mechanisms underlying the responses of respiratory chemoreceptors. Our review includes new data on nonmammalian vertebrates, which stresses that some chemoreceptor sites are of ancient origin.

Edema agudo de pulmão de pressão negativa como complicação grave de síndrome de apneia obstrutiva do sono em crianças. Relatos de casos

Introduction: Obstructive sleep apnea syndrome is related to cardiopulmonary complications in children. It is important to know its patophysiology and possible complications to help reduce risks in this group. Aims: To report three cases of severe cardiorespiratory complications of obstructive sleep apnea managed in the intensive care unit (ICU). Case report: Two children with no previous diagnosis of obstructive sleep apnea syndrome suffered acute congestive heart failure and acute lung oedema with need of ICU and improved after adenotonsillectomy. In a third case, the patient had acute lung oedema as a complication after adenotonsillectomy. Conclusions: Paediatricians and otolaryngologists must be aware of the clinical manifestations of severe sleep apnea. Early referring to treatment and special attention at pre and post surgical periods are essentials to avoid serious complications.

Efeitos da prática da natação adaptada sobre o perfil bioquímico e o estado de condicionamento físico de indivíduos com lesão medular

Introduction: The lack of physical exercises generated by immobilization of the lower limbs leads to changes in body composition that are generally associated with the imbalance of metabolic rate coupled with a sedentary status, which can result in obesity, diabetes mellitus and cardiovascular disease. Therefore, the improvement of physical fitness can contribute to promoting health and quality of life for these patients. As there is a very small number of research in this direction, our purpose was to investigate the effects of an adapted swimming program in protocol interval, for people with spinal cord injury, aiming to verify the improvement of your fitness and, consequently, some biochemical variables important for health. Methodology: The study included 17 subjects with spinal cord injury, sedentary, divided into two groups: 11 participants in the training group (TG) and 6 in control group (CG). TG was applied by a protocol of interval training in swimming for eight consecutive weeks, three times a week. The protocol employed a stroke of breaststroke in work periods of moderate to severe, and stroke in the backstroke, in periods of active recovery. The CG has not participated in any physical activity. Both groups were collecting blood for biochemical analysis, before (evaluation) and after (revaluation) the swimming program. Results and Discussion: The concentrations of triglycerides, total cholesterol and LDL-cholesterol showed no significant changes in assessment for reassessment in both groups. However the TG, the level of HDL-cholesterol were significant differences (p=0,0110), showing an improvement in posttraining, which did not occur in the CG. With respect to the state of fitness, the results revealed a significant difference in relation to time and distance covered in water when compared with the pre-training (p<0,001), showing a great improvement in the ability to shift with the stroke of breaststroke and a significant improvement in cardiorespiratory function. Conclusion: The swimming program interval used, with moderate to severe intensity, can even in a short period of time, promote positive changes in HDLcholesterol in individuals with spinal cord injury studied, and substantially improve your fitness.

Entrenamiento continuo vs. interválico corriendo en piscina profunda: Efectos sobre la salud de las mujeres obesas

Objectives. To search intermittent and continous trainning (IT and CT, respectively) effects through deep water running for the control and prevention of excessive body fat accumulation and improvement of quality of life. Methods. Experimental study composed by 30 women, aged between 34 to 58 years old, during 12 weeks, three sessions per week, 47 minutes each. Body composition, cardiorespiratory condition and Quality of Life by WHOQOL-Brief were considered. Student's and Wilcoxon's non parametric tests were applied at 5% significance level. Results. With the only exception for social domain of quality of life, all investigated variables revealed improvement in both groups for IT in comparison to CT. Conclusion. Deep water running contributes to body fat reduction, physical fitness evolution and improvement of WHOQOL-Brief domains, regardless of the trainning type conducted. © 2012 Revista Andaluza de Medicina del Deporte.