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PubMed1995

[Psychoautonomic and neurovascular disorders in patients with autonomic vascular dystonia and the hyperventilation syndrome and methods for their correction].

35 patients with vegetocirculatory dystonia and hyperventilation syndrome, but without the signs of organic lesion of nervous system were treated. The complex treatment included the breathing exercises with feedback mechanisms, the correction of psychovegetative and neurovascular disturbances, the massage of neck region and a head, psychotherapy, angioprotective, vegeto- and psychotropic drug therapy. The disappearance of acute vascular attacks and paroxysms of migrainous headache, the normalization of all breathing parameters and the improvement of vegetative status were observed in all patients.

Adolescent↗
PubMed1996

Effect of craniectomy/durotomy alone and in combination with hyperventilation, diuretics, and corticosteroids on intracranial pressure in clinically normal dogs.

OBJECTIVE: To determine the effect of craniectomy and durotomy on intracranial pressure (ICP) in clinically normal dogs. DESIGN: Two-part study (experiments A and B) involving craniectomy and durotomy, with and without treatments to lower ICP. ANIMALS: Six (experiment A) and 7 (experiment B) healthy dogs. PROCEDURE: In experiment A, craniectomy was performed in combination with durotomy, diuretic administration, methylprednisolone sodium succinate administration, and hyperventilation, and effect of these manipulations on ICP was determined. In experiment B, dogs had only craniectomy and durotomy without associated ICP-lowering treatments. During both experiments, ICP was monitored throughout the surgical procedure with a fiber optic ICP monitoring device. RESULTS: Intracranial pressure decreased after the combination of craniectomy, durotomy, and other ICP-lowering treatments in dogs of experiment A. Similar magnitude of decrease in ICP was observed in dogs of experiment B after craniectomy and durotomy. CONCLUSIONS: Comparison of these experiments indicate that surgical removal of overlying skull and incision of the dura mater can significantly decrease ICP in clinically normal dogs. CLINICAL RELEVANCE: Craniectomy and durotomy may be useful as an adjunct treatment for increased ICP.

Adrenal Cortex Hormones↗
PubMed1996

[Hypocalcemic crisis. Hypoparathyroidism--non-parathyroid origin--the most frequent form: hyperventilation syndrome].

Hypocalcemic crisis presents with the classical symptomatology of tetany plus extrapyramidal symptoms and a disordering of consciousness extending even to coma. It develops when the concentration of ionized serum calcium declines rapidly, and is very rarely found in chronic hypocalcemia. In terms of its etiology, various forms of parathyroid deficiency, and nonparathyrogenic diseases associated with hypocalcemia may be involved. Since in the latter the concentration of albumin is also diminished, and thus ionized calcium decreases to only a small extent, hypocalcemic crisis in these conditions is rare. The most common clinical form is normocalcemic tetany that occurs within the framework of the hyperventilation syndrome. Here, the ionized calcium fraction is temporarily reduced by marked alkalosis. Today, laboratory findings render establishment of the diagnosis simple. Acute therapy takes the form of parenteral calcium administration, and for long-term treatment, vitamin D metabolites, possibly in combination with oral calcium replacement is employed.

Acute Disease↗
PubMed1994

A remarkable case of hyperventilation.

We have seen a case of hyperventilation which appeared to have been caused by contact with an insecticide. Pathophysiology, epidemiology and treatment are discussed. Familiarity with the clinical symptoms greatly facilitate diagnosis, especially in emergency situations.

Adult↗
PubMedDate not supplied

[Effect of deep hyperventilation on lactate concentration in cerebrospinal fluid and brain tissue].

Deep hyperventilation (HV)--pCO2 less than 15 mm Hg--was applied in rabbits with normal intracranial pressure (ICP) and in cats with experimental brain oedema developed after epidural balloon compression. In animals with normal ICP there was an increase of CSF and tissue lactate concentration as soon as after 45 min. of HV. The lactate concentration was increasing all the time during HV. The resumption of normoventilation (2 h) after 10 h of HV was sufficient to bring the lactate level down near normality. Electron microscope studies showed only slight ultrastructural changes without destruction, even after 10 h HV. In animals with increased ICP, brain oedema was the main factor raising the lactate level, while the effect of HV was negligible.

Animals↗
PubMed1991

Influence of a twofold voluntary hyperventilation on visually evoked cortical potentials and human pupillogram.

We studied the direct and aftereffects of twofold hyperventilation (HV) on pattern reversing VEPs and pupillograms (PGs) of 19 healthy volunteers. The VEP-N80 and P100 latencies increased during HV. Both peak times were maintained for a longer period, up to 20 minutes after HV-2 ended. In addition, the PG-latency time during HV and the PG-construction time during and after HV were increased. The results indicated a temporary delay of neural afferent transmission in the visual system during and after HV. A similar delay of the nervous transmission appeared in the efferent part of the system regulating the pupillary movements after HV ended. The observed changes of the VEP and PG parameters most probably resulted from the hypocapnia cased by HV and its effect on the brain vessels, although other explanations for the changes of the VEP- and PG-parameters may have been possible.

Adult↗
PubMed2004

Hyperventilation impairs brain function in acute cerebral air embolism in pigs.

OBJECTIVE: To evaluate, in a model of cerebral air embolism (CAE), the effects of ventilation-induced hypocapnia and hyperoxemia on intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain oxygen (PbrO(2)), brain carbon dioxide (PbrCO(2)), brain pH (brpH) and levels of brain glucose and lactate. DESIGN AND SETTING: Prospective animal study in a university medical center. SUBJECTS: Fifteen Landrace/Yorkshire pigs. INTERVENTIONS: In 15 anesthetized pigs ICP, PbrO(2), PbrCO(2) and brpH were measured with multi-parameter sensors, and brain glucose and lactate by microdialysis. All these parameters were recorded for 2 h after injection of air into the internal carotid artery. Nine animals were hyperventilated (PaCO(2 )+/-25 mmHg) and hyperoxygenated (FiO(2) 1.0) and six animals were normoventilated (PaCO(2)()+/-40 mmHg with an FiO(2) 0.4) and served as controls. RESULTS. In the treatment group the ICP rose from 8+/-1 to 52+/-6 mmHg, which was similar to that in the control group (12+/-1 to 57+/-8 mmHg). At the end of the 2-h study period, there were no significant differences in PbrO(2), PbrCO(2) and brpH between the two groups. The decreased brain glucose and increased brain lactate reached severe pathological values in both groups by the end of the 2-h study period. CONCLUSIONS: Hypocapnia and hyperoxemia in acute CAE did not improve pathological functional brain parameters compared with normoventilated controls. Similarly, the pathological changes in brain glucose/lactate could also not be improved by hypocapnia and hyperoxemia.

Animals↗
PubMed1990

Effect of inhaled furosemide on the bronchial response to methacholine and cold-air hyperventilation challenges.

Inhaled furosemide has been recently demonstrated to inhibit the bronchoconstrictive effects of exercise, ultrasonically nebulized distilled water, and antigen challenge. The presumed mechanism of action of these challenges is through mast cell degranulation. We report on the effect of inhaled furosemide on cold-air hyperventilation challenge (CAHC) and methacholine challenge. We studied 10 subjects with mild to moderate asthma in a double-blind, placebo-controlled, crossover study. Inhaled furosemide did not affect FEV1 in the hour after inhalation, and there was no significant difference between placebo or furosemide on the dose of methacholine causing a 20% fall in FEV1. Our results demonstrated inhaled furosemide significantly attenuated the bronchoconstrictive effect at 6 and 9 minutes after CAHC (p less than 0.05 and 0.029, respectively) when furosemide was compared to placebo and approached significance at 12 and 15 minutes after CAHC (p = 0.052 and 0.56, respectively). Inhaled furosemide attenuates CAHC but does not effect methacholine-induced bronchoconstriction.

Administration, Inhalation↗
PubMed1991

Upper airway obstruction during nasal intermittent positive-pressure hyperventilation in sleep.

Episodes of apnoea for up to 1 min were observed in association with hypocapnia caused by passive nasal intermittent positive-pressure mechanical hyperventilation in 3 of 4 patients during sleep. Apnoea seemed to be caused by complete upper airways obstruction; we suggest that this finding was caused by active glottic closure. Avoidance of excessive hypocapnia during positive-pressure ventilation might help to avoid central-nervous-system mediated apnoeic episodes.

Adult↗
PubMed1987

Breathlessness and respiratory mechanics during reflex or voluntary hyperventilation in patients with chronic airflow limitation.

1. Six patients with chronic airflow limitation rebreathed CO2. Subsequently they voluntarily copied their stimulated breathing pattern while normocapnia was maintained. On a separate occasion four of these patients performed progressively increasing exercise and later copied these breathing patterns. 2. During all experiments flow, ventilation and pleural pressures were recorded. In addition, breathlessness was measured on a visual analogue scale every 30 s. 3. In these patients voluntary copying of either form of stimulated breathing resulted in diminished breathlessness and in some cases in complete abolition of the sensation, despite similar levels and patterns of ventilation in the two situations. 4. No systematic or consistent differences in the mechanics of breathing between stimulated and voluntarily copied breathing were found. 5. There was no correlation found between breathlessness score and any mechanical variable measured. 6. These results show that despite similarity in mechanics between stimulated and voluntary hyperventilation, the sensation of breathlessness is much diminished during the latter in these patients. This suggests that the sensation of breathlessness is more dependent upon the awareness of central processing than upon input from peripheral mechanoreceptors.

Aged↗
PubMed1999

Ventilatory characteristics in mechanically ventilated patients during manual hyperventilation for chest physiotherapy.

We measured the tidal volumes and peak inflation pressures generated during manual hyperventilation for chest physiotherapy in 25 adult ventilated patients. The average tidal volume ranged from 711 to 1511 ml, with a mean (SD) of 1120 (274) ml. There was a negative correlation (p < 0.05) between the average tidal volume and the lung injury, as measured by the Murray lung injury score. The average peak inflation pressure ranged from 37 to 74 cmH2O with a mean (SD) of 51.5 (7.6) cmH2O. There was a positive correlation (p < 0.05) between average peak inflation pressure and the lung injury score. Mean (SD) PaO2 improved by 18.3 (14.3) kPa from baseline after physiotherapy (p < 0.05). Mean (SD) PaCO2 decreased by 0.1 (0.4) kPa. As the lung score increases higher inflation pressures and smaller tidal volumes are used suggesting an increased potential for barotrauma or volutrauma in susceptible lungs.

Adult↗
PubMed1987

Hyperventilation thallium-201 myocardial imaging for the diagnosis of vasospastic angina.

In seven patients with vasospastic angina, a transient myocardial perfusion defect was demonstrated on Tl-201 myocardial imaging after hyperventilation (HV). The development of spasm on one or more coronary arteries after HV was confirmed by later coronary arteriographic studies, with the perfusing area of the coronary arteries being compatible with the scintigraphic location of the defect. Repeated 12-lead electrocardiograms failed to establish the diagnosis in one of the seven patients. It is concluded that HV Tl-201 myocardial imaging provides invaluable information in establishing a diagnosis of vasospastic angina.

Adult↗
PubMed1992

Cerebrovascular response of closed head-injured patients to a standardized endotracheal tube suctioning and manual hyperventilation procedure.

The purposes of this research were to assess the cerebrovascular response of closed head-injured patients to a standardized endotracheal tube suctioning/manual hyperventilation (ETTS/MH) procedure and determine if a 5-minute rest period, following the ETTS/MH procedure, was sufficient in length to allow cerebrovascular parameters to return to pre-intervention levels. The sample consisted of 49 head-injured patients, 18 with a baseline mean intracranial pressure (MICP) of 7.1 mm Hg, standard error (SE) .6, and 31 with a baseline MICP of 9.3 mm Hg, SE .6. A total of 145 ETTS/MH procedures were completed, 51 within the lower baseline MICP group and 94 within the higher baseline MICP group. All data were collected within 72 hours of injury using a bedside component of the Hewlett-Packard Patient Monitoring System (H-P PMS). Computer programs written specifically for this research recorded physiologic data at specified points during baseline, throughout the ETTS/MH procedure and during the recovery period. A one-way repeated measures analysis of variance (ANOVA) was used to examine whether significant differences occurred over time during the baseline, intervention and recovery periods for each dependent variable. Significant F statistics were followed by nonorthogonal, multivariate planned comparisons using the Bonferroni posthoc test to identify significant differences between baseline and each 15 second measurement of all physiologic variables during the ETTS/MH procedure and at the end of each recovery minute over a 5-minute period. Independent t tests were used to assess between group differences at each data point throughout the procedure. Findings indicated those patients whose baseline MICP was most elevated demonstrated significantly (p less than .05) lower mean arterial blood pressure, cerebral perfusion pressure, and heart rate in response to the ETTS/MH procedure when compared to those patients with a lower baseline MICP. Additionally, 60 seconds of MH was required in both patient groups following the second and third suctioning catheter pass in order to reverse a step-wise increase in MICP. Finally, at least 2 full minutes of recovery time following the completion of the ETTS/MH procedure were required to allow all measured physiologic variables to return to baseline.

Adolescent↗
PubMed1975

Artificial hyperventilation during 21 years in three cases of complete respiratory paralysis.

Three patients with paralytic poliomyelitis have been ventilated via tracheostomy with uncuffed silver cannula for 21 years, with high tidal volumes of atmospheric air (8.3, 7.2, and 5.4 ml/kg b.wt.), at a frequency of 20, passive expiration, and without periodic hyperinflation. No pulmonary complications were seen during the whole of this period. The total compliance was significantly decreased. The pulmonary physiological shunt relative to the total pulmonary blood flow (Qs/Qt) was slightly increased. PaO2 was nevertheless normal, probably due to a high alveolar PO2 caused by the hyperventilation. The physiological dead space realtive to the tidal volume (VD/VT) was within the noraml range, but VD was high in one case. Two of the patients disclosed an extremely low CO2 production and a PaCO2 averaging 12 mmHg, with small fluctuations during a 24-hour study. This profound respiratory alkalosis was only partly compensated in the arterial blood (pH: 7.54 and 7.50), suggesting a new state of acid-base equilibrium. The cerebrospinal fluid lactate was significantly increased to about 4 mmol/l, but the patients revealed no signs of impaired cerebral function. A reduction of the degree of hypocapnia by the use of a mechanical dead space is recommended.

Adult↗
PubMed1986

Exercise stress testing in angina patients with positive response to hyperventilation testing: influence of the coronary artery tone.

We studied the exercise stress test and the coronary artery tone in two groups of angina patients with comparable coronary atherosclerosis. Group I (20 males and 5 females, mean age 53.5 years) with a positive, and group II (22 males and 3 females, mean age 52.5 years) with a negative response to the hyperventilation test (HVT). A positive exercise stress test (ST depression greater than or equal to 1 mm) was found in 24 patients in group I vs. 15 in group II (p less than 0.01), despite a lower maximal rate pressure product (198 +/- 11.2 vs. 236 +/- 10.1, p less than 0.05) and maximal work load (110 W +/- 7.1 vs. 136 +/- 7.4 W, p less than 0.02) in group I. A high coronary artery tone (dilatation (DIL%) of the coronary arteries after nitroglycerin greater than or equal to 10%) was found in 18 patients in group I and in 4 in group II (p less than 0.01). DIL% was 22.6 +/- 3.8 vs. 5.8 +/- 1.4 in groups I and II, respectively (p less than 0.005). DIL% was significantly related to persistence of ST depression after exercise (r = 0.36, p less than 0.05), and 21 of 22 patients with high tone had a positive exercise stress test vs. 18 of 28 with low tone (p less than 0.05). These findings suggest that the coronary artery tone influences the response to exercise in some patients with angina. Since the patients in group I were identified by HVT, our results underline the clinical relevance of this test.

Angina Pectoris↗
PubMed1984

Seizure duration in unilateral electroconvulsive therapy. The effect of hypocapnia induced by hyperventilation and the effect of ventilation with oxygen.

Seizure duration in unilateral electroconvulsive therapy (ECT) was recorded by means of EEG in an intraindividual comparison under different alveolar O2- and CO2-concentrations. Hypocapnia induced by hyperventilation to an alveolar CO2-concentration of 2% (2 kPa) resulted in a highly significant increase in seizure duration compared to a normal CO2 of 5%, when the alveolar O2-concentration was constant at 92%. Oxygen ventilation to an alveolar O2-concentration of 92% gave no significant increase in seizure duration compared to 15%, obtained by ventilation with air, when the CO2-concentration was kept constant at 5%. Seizure duration seems to augment progressively with decreasing alveolar CO2-concentration.

Adult↗
PubMed2000

Effects of endurance training on the isocapnic buffering and hypocapnic hyperventilation phases in professional cyclists.

OBJECTIVES: To evaluate the changes produced in both the isocapnic buffering and hypocapnic hyperventilation (HHV) phases of professional cyclists (n = 11) in response to endurance training, and to compare the results with those of amateur cyclists (n = 11). METHODS: Each professional cyclist performed three laboratory exercise tests to exhaustion during the active rest (autumn: November), precompetition (winter: January), and competition (spring: May) periods of the sports season. Amateur cyclists only performed one exercise test during the competition period. The isocapnic buffering and HHV ranges were calculated during each test and defined as Vo2 and power output (W). RESULTS: No significant differences were found in the isocapnic buffering range in each of the periods of the sports season in professional cyclists. In contrast, there was a significant reduction in the HHV range (expressed in W) during both the competition (p<0.01) and precompetition(p<0.05) periods compared with the rest period. On the other hand, a longer HHV range (p<0.01) was observed in amateur cyclists than in professional cyclists (whether this was expressed in terms of Vo2 or W). CONCLUSIONS: No change is observed in the isocapnic buffering range of professional cyclists throughout a sports season despite a considerable increase in training loads and a significant reduction in HHV range expressed in terms of power output.

Adult↗
PubMed1970

Effect of intravenous sodium bicarbonate, disodium edetate (Na2EDTA), and hyperventilation on visual and oculomotor signs in multiple sclerosis.

The effects of procedures believed to produce a decrease in serum ionized calcium were tested on visual and oculomotor function in nine multiple sclerosis (MS) patients. Transient improvement in scotomas, nystagmus, and oculomotor paresis occurred with intravenous infusions of NaHCO(3) or Na(2)EDTA. Hyperventilation was also tested for its effect on nystagmus and caused marked decreases in frequency. Control experiments with saline infusions did not produce any effect. The probable mechanism and site of action for these effects is discussed. This study demonstrates that certain signs and symptoms in MS can be altered favourably by changes in the internal chemical environment and offers a new approach to the search for a symptomatic therapy in MS.

Adult↗