Cardiovascular and respiratory alterations in dogs during cervical myelography using ioversol

Subarachnoid infusion of most contrast mediums and the steps involved in performing a cervical myelography have adverse affects that can discourage its use in the radiographic diagnosis of spinal cord diseases. Thus, the cardiovascular and respiratory alterations associated with neck flexion, subarachnoid puncture, and cerebrospinal fluid drainage during subarachnoid infusion of ioversol (320mgI/mL) in dogs under general anesthesia using isoflurane were evaluated. The dogs received subarachnoid infusion of autologous cerebrospinal fluid kept at 38°C - control group (GC); ioversol 0.3mL/kg at 25°C (GI25) and ioversol 0.3mL/kg heated to 38°C (GI38). Each dog had its heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), respiratory rate (RR), oxyhemoglobin saturation (SaO2) and electrocardiography readings (PR and QT intervals) recorded. Group comparisons showed no statistical difference regarding neck positioning, subarachnoid puncture, and subarachnoid infusion of contrast medium on HR, RR and SaO2, cardiac rhythm or conduction. However, isoflurane significantly increased PR and QT intervals. Based on these findings, it is concluded that the steps involved in cervical myelography and the use of ioversol 320mgI/mL at 0.3mL/kg (25ºC and 38ºC) during cervical myelography did not result in relevant cardiovascular and respiratory alterations, except for an elevation in arterial pressure after injection of ioversol.

Cardiovascular and respiratory evaluation during cervical myelography using ioversol in dogs

The objective of this study was to evaluate cardiovascular and respiratory effects associated with neck flexion, subarachnoid puncture, cerebrospinal fluid drainage and the subarachnoid infusion of ioversol (320mgl/mL) in dogs under isoflurane general anesthesia. The dogs received infusion of: autologous cerebrospinal fluid at 38 degrees C (GC - control group); ioversol 0.3mL/ Kg at 25 degrees C (GI25) and heated to 38 degrees C (GI38). Heart rate, systolic and diastolic arterial pressure, respiratory rate, oxyhemoglobin saturation and electrocardiography readings were recorded. The results showed that cervical myelography with ioversol 320mgl/mL at 0.3mL/Kg (25 C-degrees and 38C degrees) did not significantly alter recorded parameters, except for an elevation in arterial pressure.

How do laryngeal and respiratory functions contribute to differentiate actors/actresses and untrained voices?

Purpose. The present study aimed to compare actors/actresses's voices and vocally trained subjects through aerodynamic and electroglottographic (EGG) analyses. We hypothesized that glottal and breathing functions would reflect technical and physiological differences between vocally trained and untrained subjects.Methods. Forty participants with normal voices participated in this study (20 professional theater actors and 20 untrained participants). In each group, 10 male and 10 female subjects were assessed. All participants underwent aerodynamic and EGG assessment of voice. From the Phonatory Aerodynamic System, three protocols were used: comfortable sustained phonation with EGG, voice efficiency with EGG, and running speech. Contact quotient was calculated from EGG. All phonatory tasks were produced at three different loudness levels. Mean sound pressure level and fundamental frequency were also assessed. Univariate, multivariate, and correlation statistical analyses were performed.Results. Main differences between vocally trained and untrained participants were found in the following variables: mean sound pressure level, phonatory airflow, subglottic pressure, inspiratory airflow duration, inspiratory airflow, and inspiratory volume. These variables were greater for trained participants. Mean pitch was found to be lower for trained voices.Conclusions. The glottal source seemed to have a weak contribution when differentiating the training status in speaking voice. More prominent changes between vocally trained and untrained participants are demonstrated in respiratory-related variables. These findings may be related to better management of breathing function (better breath support).

Relações entre o tempo atmosférico e doenças cardiorespiratórias na cidade de Cordeirópolis-SP

Pós-graduação em Geografia - IGCE

Respiratory metabolism of Camponotus rufipes ants: Brood and adults

The respiratory metabolism of immature forms (eggs, larvae, prepupae and pupae) of Camponotus rufipes (Hymenoptera: Formicidae) was studied at 25 degrees C, using a Warburg respirometer. Mean respiratory rates (mu l O gamma mg(-1) live weight.hr(-1)) for eggs, first instars, second instars, third instars, fourth instars, prepupae, and pupae were respectively: 2.53, 5.07, 1.23, 0.32, 0.22, 0.19 and 0.13. Adult workers with body mass between 20 and 30 mg had a mean respiratory rate of 0.43. The high respiratory rate in first instars probably reflects, besides the size influence, the metabolic costs of differentiation that occurs in this phase. (C) 1998 Published by Elsevier B.V.

Developmental changes in cold tolerance and ability to autoresuscitate from hypothermic respiratory arrest are not linked in rats and hamsters

In adult mammals, severe hypothermia leads to respiratory and cardiac arrest, followed by death. Neonatal rats and hamsters can survive much lower body temperatures and, upon artificial rewarming, spontaneously recover from respiratory arrest (autoresuscitate), typically suffering no long-term effects. To determine developmental and species differences in cold tolerance (defined here as the temperature of respiratory arrest) and its relation to the ability to autoresuscitate, we cooled neonatal and juvenile Sprague-Dawley rats and Syrian hamsters until respiration ceased, followed by rewarming. Ventilation and heartbeat were continuously monitored. In rats, cold tolerance did not change throughout development, however the ability to autoresuscitate from hypothermic respiratory arrest did (lost between postnatal days, P, 14 and 20), suggesting that the mechanisms for maintaining breathing at low temperatures was retained throughout development while those initiating breathing on rewarming were altered. Hamsters, however, showed increased cold tolerance until P26-28 and were able to autoresuscitate into adulthood (provided the heart kept beating throughout respiratory arrest). Also, hamsters were more cold tolerant than rats. We saw no evidence of gasping to initiate breathing following respiratory arrest, contributing to the hypothesis that hypothermic respiratory arrest does not lead to anoxia. (C) 2012 Elsevier B.V. All rights reserved.

Respiratory rhythm of brainstem-spinal cord preparations: Effects of maturation, age, mass and oxygenation

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

Gill chemoreceptors and cardio-respiratory reflexes in the neotropical teleost pacu, Piaractus mesopotamicus

This study examined the location and distribution of O-2 chemoreceptors involved in cardio-respiratory responses to hypoxia in the neotropical teleost, the pacu (Piaractus mesopotamicus). Intact fish and fish experiencing progressive gill denervation by selective transection of cranial nerves IX and X were exposed to gradual hypoxia and submitted to intrabuccal and intravenous injections of NaCN while their heart rate, ventilation rate and ventilation amplitude were measured. The chemoreceptors producing reflex bradycardia were confined to, but distributed along all gill arches, and were sensitive to O-2 levels in the water and the blood. Ventilatory responses to all stimuli, though modified, continued following gill denervation, however, indicating the presence of internally and externally oriented receptors along all gill arches and either in the pseudobranch or at extra-branchial sites. Chemoreceptors located on the first pair of gill arches and innervated by the glossopharyngeal nerve appeared to attenuate the cardiac and respiratory responses to hypoxia. The data indicate that the location and distribution of cardio-respiratory O-2 receptors are not identical to those in tambaqui (Colossoma macropomum) despite their similar habitats and close phylogenetic lineage, although the differences between the two species could reduce to nothing more than the presence or absence of the pseudobranch.

Respiratory manifestations of panic disorder in animals and humans: A unique opportunity to understand how supramedullary structures regulate breathing

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

The nucleus of the solitary tract and the coordination of respiratory and sympathetic activities

It is well known that breathing introduces rhythmical oscillations in the heart rate and arterial pressure levels. Sympathetic oscillations coupled to the respiratory activity have been suggested as an important homeostatic mechanism optimizing tissue perfusion and blood gas uptake/delivery. This respiratory-sympathetic coupling is strengthened in conditions of blood gas challenges (hypoxia and hypercapnia) as a result of the synchronized activation of brainstem respiratory and sympathetic neurons, culminating with the emergence of entrained cardiovascular and respiratory reflex responses. Studies have proposed that the ventrolateral region of the medulla oblongata is a major site of synaptic interaction between respiratory and sympathetic neurons. However, other brainstem regions also play a relevant role in the patterning of respiratory and sympathetic motor outputs. Recent findings suggest that the neurons of the nucleus of the solitary tract (NTS), in the dorsal medulla, are essential for the processing and coordination of respiratory and sympathetic responses to hypoxia. The NTS is the first synaptic station of the cardiorespiratory afferent inputs, including peripheral chemoreceptors, baroreceptors and pulmonary stretch receptors. The synaptic profile of the NTS neurons receiving the excitatory drive from afferent inputs is complex and involves distinct neurotransmitters, including glutamate, ATP and acetylcholine. In the present review we discuss the role of the NTS circuitry in coordinating sympathetic and respiratory reflex responses. We also analyze the neuroplasticity of NTS neurons and their contribution for the development of cardiorespiratory dysfunctions, as observed in neurogenic hypertension, obstructive sleep apnea and metabolic disorders.

Neuroglia and their roles in central respiratory control; an overview

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The effects of anesthesia with a combination of intramuscular xylazine-diazepam-ketamine on heart rate, respiratory rate and cloacal temperature in roosters

Objective To examine the anesthetic effects of a xylazine-diazepam-ketamine (XDK) combination in roosters.Study design Prospective experimental trial.Animals Six healthy white Leghorn roosters weighing 2.03 +/- 0.08 kg.Methods Each rooster was pre-medicated with xylazine (3 mg kg(-1), IM) and after 15 minutes anesthesia was induced with a diazepam (4 mg kg(-1)) and ketamine (25 mg kg(-1)) combination injected into the pectoral muscles. Heart and respiratory rates were recorded before anesthesia and every 15 minutes after induction for 165 minutes. Cloacal temperature was measured before and 15 minutes after pre-medication and every 75 minutes thereafter during anesthesia. Quality of induction and recovery were scored subjectively; duration of loss of righting reflex, abolition of response to a painful stimulus and palpebral reflex were also recorded.Results Intramuscular injection of xylazine smoothly induced loss of the righting reflex within 3-4 minutes. Loss of response to a painful stimulus occurred at 13.1 +/- 2.9 minutes (mean +/- SD) after the administration of the D-K combination, and lasted for 63.0 +/- 5.3 minutes. Roosters anesthetized with this combination had a significant decrease in heart and respiratory rates and cloacal temperature. The recovery period lasted for up to 4 hours (227.5 +/- 15.4 minutes). Quality of recovery was satisfactory for four roosters but excitation was noted in two birds.Conclusions and clinical relevance The XDK combination was a useful anesthetic technique for typhlectomy in roosters. Nevertheless this drug combination should be used with caution and cardiopulmonary parameters monitored carefully. Under the conditions of this experiment it was associated with a decreased cloacal temperature and prolonged recoveries.

Nucleus isthmi and control of breathing in amphibians

Despite recent advances, the mechanisms of neurorespiratory control in amphibians are far from understood. One of the brainstem structures believed to play a key role in the ventilatory control of anuran amphibians is the nucleus isthmi (NI). This nucleus is a mesencephalic structure located between the roof of the midbrain and the cerebellum, which differentiates during metamorphosis; the period when pulmonary ventilation develops in bullfrogs. It has been recently suggested that the NI acts to inhibit hypoxic and hypercarbic drives in breathing by restricting increases in tidal volume. This data is similar to the influence of two pontine structures of mammals, the locus coeruleus and the nucleus raphe magnus. The putative mediators for this response are glutamate and nitric oxide. Microinjection of kynurenic acid (an ionotropic receptor antagonist of excitatory amino acids) and L-NAME (a non-selective NO synthase inhibitor) elicited increases in the ventilatory response to hypoxia and hypercarbia. This article reviews the available data on the role of the NI in the control of ventilation in amphibians. (C) 2004 Elsevier B.V. All rights reserved.

Role of Locus coeruleus noradrenergic neurons in cardiorespiratory and thermal control during hypoxia

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

Ionotropic glutamatergic receptors in the rostral medullary raphe modulate hypoxia and hypercapnia-induced hyperpnea

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