The goals of this study were to assess the respiratory consequences of exposing adult zebrafish Danio rerio to chronic changes in water gas composition (hypoxia, hyperoxia or hypercapnia) and to determine if any ensuing effects could be related to morphological changes in branchial chemoreceptors. To accomplish these goals, we first modified and validated an established non-invasive technique f...

Evidence suggests both opioid mu and delta receptors may participate in the regulation of respiration at different central nervous system sites. In the past, the overlapping receptor specificity of various opioid drugs has made it difficult to dissect the receptor subtype-specific activities involved in respiratory regulation. The new family of delta receptor selective agents such as cyclic[D-P...

Changes in the rates of oxygen consumption and ammonium excretion, in intra- and extracellular acid-base status and in the rate of H+-equivalent ion transfer between animals and ambient water were measured during environmental hypercapnia in the peanut worm Sipunculus nudus. During exposure to 1 % CO2 in air, intracellular and coelomic plasma PCO2 values rose to levels above those expected from...

During our medical training, we learned that oxygen administration in patients with chronic obstructive pulmonary disease (COPD) induces hypercapnia through the 'hypoxic drive' mechanism and can be dangerous. This mindset frequently results in the reluctance of clinicians to administer oxygen to hypoxemic patients with COPD. However, this fear is not based on evidence in the literature. Here, w...

MRI may be used to measure fractional changes in cerebral oxygen metabolism via a metabolic model. One step commonly used in this measurement is calibration with image data acquired during hypercapnia, which is a state of increased CO2 content of the blood. In this study some commonly used hypercapnia-inducing stimuli were compared to assess their suitability for the calibration step. The follo...

Acute pulmonary insufficiency in chronic pulmonary disease is a medical emergency. Its therapy is difficult, and the mortality is great. A number of approaches to the problem have been employed, including the use of antibiotics, corticosteroids, oxygen, tracheotomy, and various mechanical devices to improve respiration. The physiologic derangement seen in this condition is relatively constant a...

Introduction: Surviving extreme hypercapnia from muscular respiratory failure has been only rarely reported. Case Report: A 66­year­old male developed slowly progressive weakness of the lower limbs since one year resulting in recurrent falls and later dysarthria, weakness of the left intrinsic hand muscles, general wasting, brisk tendon reflexes, and symmetric stocking type pall­hypaesthesia. E...

We measured cerebral blood flow using both the radioactive microsphere technique and the cerebral venous outflow technique in dogs anesthetized with chloralase. The effect of sympathetic stimulation on cerebral blood flow was observed during both normocapnia and prolonged hypercapnia using both blood flow techniques. The increase in blood flow with hypercapnia was the same with both methods. Du...

ALMOST a decade ago, the landmark study of low tidal volume ventilation (6 vs. 12 ml/kg ideal body weight) in the acute respiratory distress syndrome (ARDS) showed that a strategy leading in some cases to carbon dioxide retention (permissive hypercapnia) reduced mortality by a remarkable 25%. Lung protective ventilation is now the standard of care for acute lung injury and ARDS. Lack of obvious...

Hypercapnia with hyperventilation during emergence from anesthesia has been shown to reduce emergence time, yet little is known about how the subsequent recovery in the post anesthesia care unit (PACU) is affected. A mathematical model has been developed to investigate how inhaled anesthetic agents wash out of patients during recovery in order to demonstrate any difference that hypercapnia and ...