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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mature horse developed acute signs of bronchoconstriction causing hypoxemia and hypercapnia during anesthesia for computerized tomography of the maxillary sinus after i.v. administration of diatrizoate contrast medium. The horse was treated with aerosolized albuterol, atropine, and oxygen insufflation and recovered uneventfully despite severe hypoxemia and low hemoglobin saturation. The horse's condition continued to improve after treatment, and the horse was discharged with no further complications. Caution is advised with the use of contrast media in anesthetized horses.
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PMID:Treatment for a severe reaction to intravenous administration of diatrizoate in an anesthetized horse. 1507 62

Recently, it was reported that acute hypervolemia improves arterial oxygen tension in human athletes known to experience exercise-induced arterial hypoxemia. Since exercise-induced arterial hypoxemia is routinely observed in racehorses and is known to limit performance, we examined whether pre-exercise induction of acute hypervolemia would similarly benefit arterial oxygenation in maximally exercising thoroughbred horses. Two sets of experiments, namely, placebo [intravenous (IV) physiological saline] and acute hypervolemia (IV 7.2% NaCl, causing an 18.2% expansion of plasma volume) studies were carried out in random order on 13 healthy, exercise-trained thoroughbred horses, 7 days apart. An incremental exercise protocol leading to 120 s of galloping at 14 m s(-1) on a 3.5% uphill incline was used. Galloping at this workload elicited maximal heart rate and induced pulmonary hemorrhage in all horses in both treatments. In the placebo study, arterial oxygen tension decreased to 76.1 (2) mmHg (P<0.0001) at 30 s of maximal exertion, but further significant changes did not occur as exercise duration increased to 120 s [arterial oxygen tension 72.4 (2) mmHg]. A significant arterial hypoxemia also developed in galloping horses in the acute hypervolemia study [arterial oxygen tension at 30 and 120 s was 76.7 (1.7) and 71.9 (1.6) mmHg, respectively], but significant differences between treatments could not be demonstrated. In both treatments, a similar desaturation of arterial hemoglobin was also observed at 30 s of maximal exercise, which intensified with increasing exercise duration as hyperthermia, acidosis and hypercapnia intensified. Thus, acute expansion of plasma volume did not benefit arterial oxygenation in maximally exercising thoroughbred horses.
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PMID:Acute hypervolemia does not improve arterial oxygenation in maximally exercising thoroughbred horses. 1545 36

Perinatal brain injury has been associated with impaired cerebral blood flow (CBF) pressure autoregulation. The brain of 3- to 5-d-old rat pups is immature and similar to that of a preterm infant, and therefore we tested cerebral vasoreactivity in that animal. CBF pressure autoregulation was tested in 20 Wistar pups during normocapnia and hypercapnia, respectively. Hypotension was induced by hemorrhage and cerebral perfusion was monitored with laser Doppler flowmetry and near-infrared spectroscopy. Systolic blood pressure was measured noninvasively from the tail. During normocapnia, the autoregulatory plateau was narrow. Resting systolic blood pressure (SBP) was 39.2 mm Hg and CBF remained constant until SBP decreased below 36.0 mm Hg (SE 0.8). Below the lower limit, CBF declined by a mean of 2.7% per mm Hg [95% confidence interval (CI), 2.4-3.0%], and hemoglobin difference (HbD) and total hemoglobin (HbT) changed proportionally to CBF. After inhalation of carbon dioxide, CBF increased significantly by a mean of 17.7% (95% CI, 13.7-22.8%). The CBF-CO2 reactivity was estimated to 13.4% per kPa (95% CI, 2-24.8%), p=0.026. Over the range of SBP (6-54 mm Hg), a linear relationship between CBF and SBP was found during hypercapnia, indicating abolished pressure autoregulation. A linear correlation between CBF and HbD was found (r=0.80). CBF pressure autoregulation and reactivity to CO2 operate in the newborn rat. This model may be useful for future investigations concerning perinatal pathophysiology in the immature brain.
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PMID:Cerebral pressure autoregulation and vasoreactivity in the newborn rat. 1558 87

Acute dyspnea represents a diagnostic challenge even for the experienced physician. There are no prospectively evaluated diagnostic algorithms dealing with this frequent clinical problem. First of all, the emergency has to be assessed and life supporting measures have to be considered. In addition to a thorough medical history and clinical examination, chest X-ray, spirometry, ECG, hemoglobin measurement, BNP and D-dimer testing represent valuable diagnostic tools and are available to GP's. Most commonly, acute dyspnoea is pulmonary or cardiac in origin. Up to one third of all cases will have several causes. Functional dyspnea is difficult to diagnose but should be taken into consideration after excluding any somatic cause. Hyperventilation is found in both, organic and non organic diseases, and is therefore an inappropriate criterion to differentiate between the two. The mainstay in the management of any symptom is to primarily treat the underlying disease. A significant hypoxemia (SO2 < 90%, pO2 < 60 mmHg) ought to be corrected by supplemental oxygen. It is inappropriate to withhold oxygen from patients with COPD and severe hypoxemia just to avoid hypercapnia. Besides oxygen, opiates efficiently relief dyspnoea but harbour the risk of respiratory depression, altered mental status or aspiration.
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PMID:[Acute dyspnea--what should I not forget?]. 1599 36

The objective of this study is to correlate regional cerebral blood concentration measurements made with near infrared spectroscopy to simultaneous local measurements of ultrasound contrast agent (CA) densitometry. Experiments were performed with piglets (7 kg) under general anesthesia. The cerebral blood flow (CBF) and volume (CBV) were changed by inducing various degrees of hypercapnia. NIRS measurements were performed with a quasi-continuous wave system, using an optode distance of 3-6 cm. The concentration changes in oxygenated and deoxygenated hemoglobin and their sum and difference (cO2Hb, cHHb, ctHb, cHbD) were continuously calculated. Ultrasound contrast agent (SF6) was administered as a short intra-venous bolus. Ultrasound equipment was used in pulse inversion second harmonic gray scale imaging mode at low transmit power setting. Three regions-of-interest (0.25 cm2) were analyzed in each image. Wash-in curves were constructed as spatial mean gray level vs. time. The variables collected with both methods changed according to the induced changes in the physiological condition. Changes in the PaCO2, pH and carotid flow induced highly correlated changes in cO2Hb, cHHb, ctHb and cHbD, and in the variables derived from CA analyses. NIRS and CA methods measure regional, respectively, local changes in CBV and CBF. Moreover, NIRS can yield complementary information about the cerebral oxygenation.
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PMID:Assessment of local changes of cerebral perfusion and blood concentration by near infrared spectroscopy and ultrasound contrast densitometry. 1612 27

Neurophysiological studies have shown that serotonergic ligands that bind to 5-HT1A, 5-HT7, and 5-HT4 serotonin receptors in brain stem have beneficial effects on respiratory neurons during opioid-induced respiratory depression. The effect of these ligands on respiratory function and pulmonary performance has not been studied. We therefore examined the effects of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), an agonist of 5-HT1A and 5-HT7 receptors, and zacopride, an agonist of 5-HT4 receptors, to establish whether these ligands would reverse opioid-induced respiratory depression and hypoxia without affecting the immobilizing properties of the opioid drug etorphine. When etorphine was used to sedate and immobilize goats, it significantly decreased respiratory rate (P = 0.013), percent hemoglobin oxygen saturation (P < 0.0001), and arterial oxygen partial pressure [Pa(O2); F(10,70) = 5.67, P < 0.05] and increased arterial carbon dioxide partial pressure [F(10,70) = 3.87, P < 0.05] and alveolar-arterial oxygen partial pressure gradient [A-a gradients; F(10,70) = 8.23, P < 0.0001]. Zacopride and 8-OH-DPAT, coadministered with etorphine, both attenuated the effects of etorphine; respiration rates did not decrease, and percent hemoglobin oxygen saturation and Pa(O2) remained elevated. Zacopride decreased the hypercapnia, indicating an improvement in ventilation, whereas 8-OH-DPAT did not affect the hypercapnia and, therefore, did not improve ventilation. The main beneficial effect of 8-OH-DPAT was on the pulmonary circulation; it improved oxygen diffusion, indicated by the normal A-a gradients, presumably by improving ventilation perfusion ratios. Neither zacopride nor 8-OH-DPAT reversed etorphine-induced catatonic immobilization. We conclude that serotonergic drugs that act on 5-HT1A, 5-HT7, and 5-HT4 receptors reverse opioid-induced respiratory depression and hypoxia without reversing catatonic immobilization.
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PMID:Zacopride and 8-OH-DPAT reverse opioid-induced respiratory depression and hypoxia but not catatonic immobilization in goats. 1616 6

Thirty practically healthy individuals and 111 patients suffering from chronic obstructive pulmonary disease (COPD) with I to III degree chronic respiratory failure (CRF) were examined. The study established a negative correlation between partial oxygen pressure in arterial blood (AB), the degree of bronchial obstruction, hemoglobin saturation, and the degree of CRF. It was found that the degree of CRF was in a significant correlation with the degree of pulmonary physiological (alveolar) shunt and the degree of hypercapnia. The author proposes an algorithm for precise determination of the degree of CRF that includes calculation of alveolar shunt as an integral parameter reflecting the degree of AB gas changes.
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PMID:[Evaluation of the degree of respiratory failure in patients with chronic obstructive pulmonary disease]. 1752 Aug 82

We developed a mathematical model of human respiration in the awake state that can be used to predict changes in ventilation, blood gases, and other critical variables during conditions of hypocapnia, hypercapnia and these conditions combined with hypoxia. Hence, the model is capable of describing ventilation changes due to the hypocapnic-hypoxia of high altitude. The basic model is that of Grodins et al. [Grodins, F. S., J. Buell, and A. J. Bart. J. Appl. Physiol. 22:260-276, 1967]. We updated the descriptions of (1) the effects of blood gases on cardiac output and cerebral blood flow, (2) acid-base balance in blood and tissues, (3) O2 and CO2 binding to hemoglobin and most importantly, (4) the respiratory-chemostat controller. The controller consists of central and peripheral sections. The central chemoceptor-induced ventilation response is simply a linear function of brain P(CO2) above a threshold value. The peripheral response has both a linear term similar to that for the central chemoceptors, but dependent upon carotid body P(CO2) and with a different threshold and a complex, nonlinear term that includes multiplication of separate terms involving carotid body P(O2) and P(CO2). Together, these terms produce 'dogleg'-shaped curves of ventilation plotted against P(CO2) which form a fan-like family for different values of P(CO2). With this chemical controller, our model closely describes a wide range of experimental data under conditions of solely changes in P(CO2) and for short-term hypoxia coupled with P(CO2) changes. This model can be used to accurately describe changes in ventilation and respiratory gases during ascent and during short-term residence at altitude. Hence, it has great applicability to studying O2-delivery systems in aircraft.
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PMID:A mathematical model of human respiration at altitude. 1767 6

Adaptive mechanisms may diminish the detrimental effects of recurrent nocturnal hypoxia in obstructive sleep apnea (OSA). The potential role of elevated carbon dioxide (CO2) in improving brain oxygenation in the patients with severe OSA syndrome is discussed. CO2 increases oxygen uptake by its influence on the regulation of alveolar ventilation and ventilation-perfusion matching, facilitates oxygen delivery to the tissues by changing the affinity of oxygen to hemoglobin, and increases cerebral blood flow by effects on arterial blood pressure and on cerebral vessels. Recent clinical studies show improved brain oxygenation when hypoxia is combined with hypercapnia. Anti-inflammatory and protective against organ injury properties of CO2 may also have therapeutic importance. These biological effects of hypercapnia may improve brain oxygenation under hypoxic conditions. This may be especially important in patients with severe OSA syndrome.
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PMID:Role of hypercapnia in brain oxygenation in sleep-disordered breathing. 1769 Dec 28

White rhinoceroses (Ceratotherium simum) anesthetized with etorphine combinations develop severe pathophysiologic changes, including hypoventilation, hypoxemia and metabolic acidosis. The aim of this study was to evaluate the addition of butorphanol to the immobilizing mixture on the cardiopulmonary effects in free-ranging white rhinoceroses darted from the helicopter. In the control group (n=15), the rhinoceroses were anesthetized with etorphine, azaperone, detomidine, and hyaluronidase administered intramuscularly. In the treatment group (n=16), 10-20 mg of butorphanol was added to the combination. Within 10 min of becoming immobile, vital parameters (heart rate, respiratory rate, and temperature) and blood gas analyses were taken, and measurements were repeated after 10 (treatment group) and 20 min (control group). Both groups showed respiratory and metabolic acidosis, hypoxemia, and hypercapnia. In the control group, the arterial partial pressure of oxygen was significantly higher and the alveolar-to-arterial oxygen pressure gradients were significantly lower in all body positions compared with the butorphanol group. Oxygen hemoglobin saturation in the control group was higher than in the butorphanol group only in the lateral position. Improvements in arterial oxygen levels were observed in all animals when placed in sternal recumbency. There were no significant differences in the mean induction times between groups, but the distance the butorphanol group ran was significantly less after darting than in the control group. By adding butorphanol to the immobilizing mixture, no benefits in ventilation were seen; although, size differences make comparisons difficult. Running for a shorter distance during induction could be beneficial in the prevention of severe acid-base imbalances and capture myopathy.
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PMID:The cardiopulmonary effects of etorphine, azaperone, detomidine, and butorphanol in field-anesthetized white rhinoceroses (Ceratotherium simum). 1793 46


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