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Query: UMLS:C0085383 (hypocapnia)
 1,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ventilatory effects of graded reductions in brain bloow flow (BBF) were studied in unanesthetized goats. At a BBF of 85% of control (PVO2 = 29.2 Torr, PVCO2 = 47.3 Torr) there were no clear ventilatory effects. At BBF of 70% of control (PVO2 = 25.2, PVCO2 = 50.5) and 50% of control (PVCO2 = 22.3, PVCO2 = 53.0) there was hyperpnea, due primarily to an increase of tidal volume. Further reduction of BBF (avg of 42% of control) first produced intense tachypnea and then (30--40% of control) caused apnea that was reversible. At 50% BBF there was a reduction of brain O2 consumption, (4.67--4.00 ml/min) and an increase in systemic O2 consumption. beta-Adrenergic blockade prevented the increase in systemic O2 consumption and reduced the hyperpnea by two-thirds at 50% BBF; the residual hyperpnea was associated with hypocapnia in contrast to the hyperpnea prior to beta-adrenergic blockade, which was virtually isocapnic. The data suggest that hyperpnea due to brain ischemia is a result of both brain acidosis and systemic hypermetabolism. The similarity of the pattern of responses to that previously reported for progressive carboxyhemoglobinemia suggests that brain hypoxia is a determinant of the ventilatory responses to brain ischemia.
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PMID:Effects of graded reduction of brain blood flow on ventilation in unanesthetized goats. 46 49

The clinical profiles of 15 patients with acute pulmonary embolism (APE) were analysed. The most common symptoms of APE were tachypnea and tachycardia with sudden onset. Both PO2 and PCO2 had decreased in almost all patients (mean PO2: 50 mmHg, PCO2: 30 mmHg). Chest roentgenogram (X-P) revealed hyperlucency of the lung field, prominence of proximal pulmonary artery and cardiac enlargement. ECG showed SI QIII TIII and ST-T changes in half of the cases. These changes, however, disappeared within 4 days in most patients. Lung scan and digital subtraction pulmonary angiography were useful for the diagnosis. Sixty percent of patients recovered only by medical therapy, and embolectomy was performed in only two patients. Fifty-three percent of patients were, however, considered to be candidates for the embolectomy, and half of them died because of ineffective medical therapy. From these results we concluded that the combination of severe hypoxemia and hypocapnia with abnormal chest X-P can be used for a diagnostic or therapeutic decision. If a patient has those findings, pulmonary angiography is recommended together with thrombolytic therapy. If a large embolus is detected, embolectomy is mandatory. The need for surgical therapy for APE is greater than we had imagined.
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PMID:[Clinical profile and treatment of acute pulmonary embolism]. 157 48

In anesthetized dogs with natural breathing, embolisation of pulmonary arterial bed increased systolic pressure in the right ventricle of the heart up to 60.0-113.0 mm Hg. Within 6 hrs the pressure far exceeded initial and control parameters in the minor circulation circle. Tachycardia and tachypnea as well as a reduction of the left ventricle contractions and a decrease of arterial pressure occurred. The massive emboli was followed by an obvious hypoxia and an insignificant hypocapnia with no essential shifts in the blood acid-base balance. Subsequent interstitial oedema of pulmonary tissue may be due both to the changes in the lung hemodynamics and to direct damaging of endothelium in the microvessels.
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PMID:[The systemic and regional changes in the modelling of a massive pulmonary artery embolism]. 196 89

We studied the effects on breathing of seizures induced by focal injection of penicillin G into the parietal cortex in 13 anesthetized cats. Electrocorticograms, ventilation, end-tidal PCO2, and intrapleural and arterial pressures were monitored; changes of these variables were related to the stages of motor seizure. The first respiratory responses, tachypnea and hyperpnea, usually occurred before any peripheral muscular contractions developed. Progression of the seizure was always accompanied by further tachypnea and hyperpnea. The hyperpnea associated with all stages of seizure activity resulted in hypocapnia, which was sustained even during prolonged tonic-clonic motor convulsions that caused a threefold increase of metabolic rate. The extreme tachypnea of tonic generalized convulsions led to increased end-expiratory lung volume because of dynamic hyperinflation associated with very short expiratory durations in the tonic phase. We suggest that the profound effects of seizures on respiration are by feedforward mechanisms from the cortical focus itself and from subcortical circuits, such as hypothalamus, that become involved during seizure propagation and generalization. Peripheral respiratory feedback mechanisms are not important for the genesis of seizure-induced hyperpnea.
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PMID:Respiratory responses to focal and generalized seizures in cats. 203 5

A 52-year-old woman developed subjective right hemiparesthesias over a two-day period. Because of a paucity of physical findings, apparent anxiety with tachypnea, and a respiratory alkalosis with hypocapnia, a diagnosis of hyperventilation syndrome was considered. However, because of the unilateral symptoms, a computed tomography scan was performed, demonstrating a left posterior thalamic infarct. Most reports of thalamic infarct indicate altered mental status, vertical gaze palsies, or sensorimotor hemiparesis with sensory involvement predominant. The case of a patient with thalamic hemorrhage who presented with only hemiparesthesia is reported to heighten clinicians' awareness of this diagnosis.
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PMID:Thalamic hemorrhage imitating hyperventilation. 238 66

The effects of the level of oxygenation on the respiratory response to heat exposure have been studied in conscious cats during normoxia, severe or mild hypocapnic hypoxia [inspired O2 fraction (FIO2) = 0.11 or 0.13], or hyperoxia. Several cats were also studied during severe normocapnic hypoxia. Experiments were repeated while the same animals were chronically carotid body denervated (CBD). The increase in respiratory frequency (f) leading to thermal tachypnea occurred at a lower body temperature (Tb) in severe hypocapnic hypoxia than in ambient air, but this effect was less pronounced when hypocapnia was corrected. No significant changes were observed during mild hypoxia or hyperoxia compared with normoxia in intact animals. After CBD, thermal tachypnea occurred at lower Tb in air than it did with intact animals in three of five cats, and it also occurred at lower Tb in mild hypocapnic hypoxia compared with air. It appears, therefore, that in conscious cats exposed to heat load 1) severe hypoxia enhances thermal tachypnea, 2) this effect persists after CBD, which suggests that it originates from a central action of hypoxia, and 3) the chemoreceptor afferents, to some degree, inhibit the onset of thermal tachypnea, as was previously observed for hypoxic tachypnea, which appears only in CBD cats (J. Appl. Physiol. 49: 769-777, 1980). Therefore, triggering of thermal and hypoxic tachypnea may involve common central mechanisms, probably located in the diencephalic structures under the control of afferents from arterial chemoreceptors.
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PMID:Effects of hypoxia on thermal polypnea in intact and carotid body-denervated conscious cats. 279 59

A patient with acute hyperleukocytotic myelogenous leukemia who presented with acute respiratory distress is reported. Clinical manifestations included dyspnea, tachypnea, hyperventilation, and cyanosis. Blood gas analysis revealed hypoxemia, hypocapnia, and metabolic acidosis. Chest X-ray and perfusion lung scanning were normal. Pulmonary leukostasis syndrome (PLS) was later confirmed at autopsy. In a patient with hyperleukocytosic from acute nonlymphocytic leukemia and respiratory distress, a normal perfusion lung scintigraph should make one consider the PLS.
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PMID:Acute respiratory failure in hyperleukocytotic acute myeloid leukemia: the role of perfusion lung scintigraphy. 316 47

Infants born to opiate-dependent women frequently have low birth weights and low 1- and 5-min Apgar scores. Significant postnatal problems, excluding neonatal withdrawal, can include jaundice, infection, aspiration pneumonia, transient tachypnea, and hyaline membrane disease. Neonatal abstinence may be severe and persist for as long as 3 months. Abstinence symptoms can include central nervous system hyperirritability, gastrointestinal dysfunction, respiratory distress, tremors, fever, high-pitched cry, increased muscle tone, uncoordinated sucking and swallowing reflexes, dehydration, and possible electrolyte imbalance. During the first week of life, increased respirations associated with hypocapnia and alkalosis may occur. The Brazelton Neonatal Behavioral Assessment Scale has been used to quantify the neurobehavioral effects on neonates of narcotics administered prenatally. A marked decline in mortality rates of infants born to opiate-dependent mothers is evident. In Philadelphia, infant morbidity has been related not only to the type of maternal narcotic dependence, but also to the amount of prenatal care. Infants whose mothers received prenatal care have been found to have higher birth weights similar to infants of control mothers. Although the newborn with intrauterine exposure to narcotic agents may appear normal at birth, the effects of the pharmacologic agent may not become apparent until later in development. To obtain a more favorable outcome for the high-risk mother and child involved in the problems of perinatal addiction, several recommendations are proposed.
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PMID:Effects of maternal opiate abuse on the newborn. 388 86

Ten splenectomized and ten nonsplenectomized conscious dogs were subjected to hemorrhage of 41% of their blood volume over a 15-minute period. Hemodynamic and metabolic variables were monitored for 4 hours after hemorrhage. Mortality (100%) occurred in the splenectomized group. Significant (P < 0.001) hemodynamic responses after hemorrhage included hypotension, tachycardia, low central venous pressure, and decreased ECG voltage of the R wave. Tachypnea was noted in the absence of hypoxia, hypercapnia, and acidosis inthe nonsplenectomized dogs. Significant (P < 0.001) hypocapnia and mean PCO2 values of 13.9 MM of Hg and 23.5 mm of Hg in splenectomized and nonssplenectomized dogs, respectively, was noted. Mean hemoglobin levels were significantly (P < 0.001) decreased after hemorrhage in the splenectomized dogs. The absence of a change in hemoglobin in thenonsplenectomized dogs was attributed to the translocationof extracellular fluid into the vascular space which diluted the high concentration of RBC from splenic contraction. Other changes noted after hemorrhage were hyperglycemia, increased blood cortisol, and increased pyruvate and lacte levels. Changes were not noted in pyruvate-to-lactate ratios.
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PMID:Experimental hemorrhage in splenectomized and nonsplenectomized dogs. 740 89

A 92-year-old woman was admitted to our hospital due to hypertension, nausea, pain in the anterior part of the chest, epigastralgia, and tachypnea. During the initial examination of the patient in the emergency ward, she was very excited, howled, and both her hands were numb. Arterial blood gas analysis revealed a marked alkalemia (pH greater than 7.55) and hypocapnia (Pco2 24.1 mmHg). After paper bag re-breathing, the pH and Pco2 were within normal limits. Because there was no lesion in the lungs or the brain that would account for hyperventilation and convulsions, the attack was considered to be a manifestation of hyperventilation syndrome should be carefully considered in the differential diagnosis of disturbance of consciousness even in elderly patients.
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PMID:[Hyperventilation syndrome in a very old woman]. 915 99


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