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PubMed1988

Duration of hyperventilation and outcome in infants with persistent pulmonary hypertension.

Twenty-one infants with the diagnosis of persistent pulmonary hypertension had serial assessments of growth and neurologic development through 12 months of corrected age. Seven infants (30%) had one or more adverse physical outcomes during the first year of life. Four infants (19%) had severe neurologic impairment; seven babies had mild to moderate delay, and 11 babies were found to have no abnormality. Adverse outcome was related to significantly to the duration of hyperventilation, such that the infants without and with abnormalities spent 60 +/- 53 hours and 124 +/- 52 hours hyperventilated, respectively (P less than .01). Our results show that the need for prolonged hyperventilation in infants with persistent pulmonary hypertension is associated with poorer neurodevelopmental outcome.

Cognition↗
PubMed1989

[Airway responsiveness to isocapnic hyperventilation with room temperature air].

Isocapnic hyperventilation (IHV) with room temperature dry gas was evaluated in 63 asthmatics and 33 normal subjects, in order to asses the clinical relevance of the technique as a simplified test of airways hyperreactivity. The results between IHV and methacholine challenge (MCH) were compared in 32 asthmatics. Mostly asthmatics revealed obvious bronchoconstriction and average 21.4 +/- 14.8% decrease in FEV1 (delta FEV1) after hyperventilation. Among the normal subjects delta FEV1 was average 3.8 +/- 2.0%. Obvious difference was show between the normal and the asthmatics in reaction following IHV (P less than 0.001). When the criterion for a positive reaction to IHV was a decrease in FEV1 of 10 percent or greater, the sensitivity and specificity of the test were 85% and 100% separately. Three of the asthmatics demonstrated bronchodilative reaction and FEV1 increased notably than the base after hyperventilation. The positive percentages of IHV and MCH were similar (P greater than 0.05). The results suggest the IHV with room air determine bronchial reactivity is a simple and secure method.

Adolescent↗
PubMed1986

Water loss from the respiratory tract during hyperventilation in normal subjects and in asthmatics.

Expiratory water loss was measured in four asthmatics and in four healthy subjects by leading the expired air through a tube filled with silicagel during hyperventilation. No difference in water loss was seen as the average water loss was 0.025 g/l for the asthmatics and 0.029 g/l for the healthy subjects. After hyperventilation PEF decreased more than 20% in the asthmatics while no change was seen in the lung function of the healthy subjects. It is concluded that expiratory water loss per se is not the reason for the decrease in lung function seen in asthmatics after exercise and hyperventilation.

Adult↗
PubMed1984

[Significance of oxygen hyperventilation in bronchofiberscopy in intensive medicine].

In 25 patients (group I = 15 patients, group II = 10 patients) we examined the influence of bronchoscopic aspiration on lung function. PaO2 and PaCO2 were measured before, during, and after bronchoscopic aspiration. In all cases the insertion of the bronchofiberscope was performed by means of a transnasal tube. In 15 patients of Group I an increase in PaO2 followed, and because of this we could reduce FiO2 after bronchoscopic examination. The 10 patients of Group II were hyperventilated before and during the examination (AMV = 150 ml/kg body weight, FiO2 = 1.0). Hyperventilation increased in 10 patients the PaO2 from 53 (43-121) mmHg to 112 (96-225) mmHg. During bronchoscopy PaO2 decreased from 154 (96-225) mmHg to 102 (70-196) mmHg in 8 of the 10 patients. Two patients showed an increase in PaCO2. A third patient had an obvious increase in PaCO2 from 53 to 65 mmHg. Only 24 hours later we observed normalization of PaCO2 and an increase in PaO2. According to these results, hyperventilation (FiO2 = 1.0) during bronchoscopic examination is necessary in intensive care patients. Insertion of the bronchoscope should be performed via tracheal tube. Strict monitoring is imperative.

Bronchoscopy↗
PubMed1995

Comparing arterial and end-tidal carbon dioxide values in hyperventilated neurosurgical patients.

BACKGROUND: Hyperventilation is a frequently used method for inducing hypercarbia in neurosurgical patients. This practice requires careful carbon dioxide monitoring that might be replaced by a less expensive and less invasive alternative to arterial blood gas monitoring. OBJECTIVE: To determine the accuracy of end-tidal carbon dioxide monitoring in hyperventilated neurosurgical patients. METHODS: Nineteen adult patients requiring hyperventilation for the reduction of intracranial pressure following head injury or neurosurgery were enrolled from the surgical intensive care unit of a level I trauma center. A correlation design was used to compare arterial carbon dioxide tensions and end-tidal carbon dioxide measurements during specific periods; secondary analysis with bias and precision estimates was performed. Also, changes in arterial carbon dioxide tensions were compared with simultaneous changes in end-tidal carbon dioxide values. RESULTS: End-tidal carbon dioxide values showed a moderately acceptable correlation with arterial blood gas measurements. However, changes in end-tidal carbon dioxide values failed to correlate with simultaneous changes in arterial carbon dioxide tension measures. Bias and precision measures confirmed these findings. CONCLUSION: In this patient sample, changes in end-tidal carbon dioxide values did not accurately reflect changes in arterial carbon dioxide tension levels in the intensive care setting. Further technological advances in noninvasive carbon dioxide monitoring may lead to a significant cost savings over traditional arterial blood gas analysis.

Adult↗
PubMed1995

[Neonatal apnea after general anesthesia--effects of intraoperative hyperventilation and serum ionized Ca concentration].

The relationship between neonatal apnea following general anesthesia and serum ionized calcium (Ca2+) concentration was examined in 13 neonates who had received intraoperative hyperventilation. In all cases, preoperative serum Ca2+ concentration was within normal limits. The anesthesia was maintained by nitrous oxide and oxygen. At the end of anesthesia, the incidence of abnormal breathing such as apnea, periodic breathing or subcostal retraction and their activity were investigated. Five minutes after intravenous administration of 2% CaCl2 solution (16 mg.kg-1), the same parameters were compared with the values before CaCl2 administration. As we used only Ca2+ free solution for fluid therapy during operation, serum Ca2+ concentration decreased gradually under general anesthesia, but after CaCl2 administration, it increased and the incidence of abnormal breathing decreased. To determine the relationship between hyperventilation and the incidence of abnormal breathing, the data were analyzed by dividing the patients into two groups based on PaCO2 level, a lower PaCO2 group (intraoperative PaCO2 < 30 mmHg, n = 5) and a higher PaCO2 group (PaCO2 > or = 30 mmHg, n = 8). But there was no significant relationship between them. In conclusion, this study demonstrates that the Ca administration has a favorable effect on respiratory system and motor activity, but we cannot relate the incidence of postoperative abnormal breathing to the degree of hyperventilation.

Anesthesia, General↗
PubMedDate not supplied

Non-hyperventilation respiratory therapy of persistent pulmonary hypertension of the newborn.

Persistent pulmonary hypertension of the newborn (PPHN) is one of the most challenging situations in the neonatal intensive care nursery and it is associated with a high mortality rate. Hyperventilation therapy has been recommended as the primary ventilator management during recent decades. The associations of pulmonary barotrauma, chronic lung disease and hearing impairment raised the questions of significant pulmonary and neurological complications with this therapeutic modality. From July 1990 to April 1993, 14 cases of neonatal persistent pulmonary hypertension were treated with nonhyperventilation respiratory therapy at the Chang Gung Memorial Hospital. The goals of this therapy were to attain a pH level between 7.40 and 7.50, a PaO2 level between 60 and 90 mmHg and a PaCO2 level between 30 and 50 mmHg. High peak inflating pressure (> 35 cmH2O) and high ventilator rates (> 60/min) were avoided. The average duration on a ventilator was 6.8 +/- 2.9 days. Four patients had pulmonary barotrauma (29%); three of which were pulmonary interstitial emphysema and one pneumothorax. Three patients died (21%). Only one patient had neurological sequelae. No one had developed chronic lung disease. The non-hyperventilation approach for PPHN may be considered as an alternative ventilator management before starting a more aggressive hyperventilation therapy.

Female↗
PubMed1994

Treatment of persistent pulmonary hypertension of the newborn without hyperventilation: an assessment of diffusion of innovation.

OBJECTIVE: The treatment of neonates with persistent pulmonary hypertension of the newborn (PPHN) is controversial with no consensus on diagnostic criteria or treatments. Hyperventilation has been the therapeutic mainstay. However, two widely variant alternative approaches have been proposed: ventilation without induced alkalosis, or more aggressive therapies such as high frequency ventilation or extracorporeal membrane oxygenation. We wished to determine the extent to which these alternative treatments have diffused into practice. METHODS: A forced choice questionnaire was mailed to a sample representing 10% of 3740 practicing neonatologists. Sixty percent of those surveyed responded. Data on treatment practices was tabulated. Subanalyses with respect to training era, practice site, and geographic region were performed. RESULTS: In patients with meconium aspiration syndrome, without evidence of PPHN, 36% described their initial management as hyperventilation. If PPHN was confirmed, hyperventilation was used in 90% of patients by 44% of the respondents. Muscular paralysis and inotropic support were also used frequently. Alkali and vasodilator infusion were used less frequently. The gentle ventilation strategy proposed by Wung and James at Columbia Babies Hospital was used infrequently by 47% of respondents. Gentle ventilation was used more frequently by board-certified neonatologists than those not certified. No significant differences in practice were identified by geographic region or era of training. When standard treatment failed, only 40% of the respondents utilized rescue treatments such as high frequency ventilation or extracorporeal membrane oxygenation. CONCLUSIONS: This study documents that gentle ventilation, an easily and inexpensively adopted innovation, has not diffused into practice significantly while more expensive high technology treatments, such as high frequency ventilation and extracorporeal membrane oxygenation, have penetrated more significantly.

Diffusion of Innovation↗
PubMedDate not supplied

Hyperventilation in the head-injured patient: an effective treatment modality?

Mortality and poor functional outcomes remain major problems in patients who experience a severe head injury. Cerebral injury from high intracranial pressure contributes to the head injury. A basic postulate in the care of the head-injured patient is the prevention of secondary cerebral damage through the management and prevention of high intracranial pressure. Hyperventilation, once an established intervention in the treatment and control of intracranial hypertension in patients with severe neurologic injury, has become increasingly controversial. This article reviews (1) the normal physiology of the brain, (2) the pathophysiologic changes that occur during head injury, and (3) the theoretical rationale of hyperventilation and its interaction with nursing care. A case study is presented to highlight how the patient's response to a routine nursing procedure, endotracheal suctioning, may change as a result of hyperventilation.

Adult↗
PubMed1998

[Usefulness of thallium-201 myocardial scintigraphy during hyperventilation and accelerated exercise test in patients with vasospastic angina and nearly normal coronary artery].

The usefulness of thallium-201 (201Tl) myocardial scintigraphy was studied in 109 patients with vasospastic angina who had nearly normal coronary arteries (degree of stenosis < 50%). Coronary spasm was confirmed by pharmacologic agents in all 109 patients from January 1991 to June 1996. The appearance rate of visual redistribution on 201Tl myocardial scintigraphy was compared between four groups, 34 patients performing graded bicycle ergometer exercise starting at a work load of 50 W with increments of 25 W every 3 min [Ergo (3) group], 14 patients performing hyperventilation for 5 min [HV (5) group], 31 patients performing bicycle ergometer exercise with increments of 25 W every 1 min after 5 min hyperventilation [HV (5) + Ergo (1) group], and 30 patients at rest (Rest group). The value of the visual redistribution rate on 201Tl myocardial scintigrams in the HV(5) + Ergo (1) group (65%) was higher than that in the patients of other groups [Ergo (3) 41%, HV (5) 43%, Rest 33%]. However, there were no significant differences between the four groups. Stress 201Tl imaging after hyperventilation and accelerated exercise is useful to disclose ischemic evidence in about two thirds of patients with vasospastic angina and nearly normal coronary arteries, whereas about 40% of patients had visual redistribution on 201Tl myocardial scintigrams by performing standard procedures.

Acetylcholine↗
PubMed1985

Central neurogenic hyperventilation in a conscious patient with a primary cerebral lymphoma.

The clinical and neuropathological findings of a patient with central neurogenic hyperventilation are described. The patient had an extensive primary central nervous system lymphoma but no lesions below the level of the superior colliculus. The possible mechanism of central neurogenic hyperventilation is discussed with reference to the present case and those previously described.

Brain↗
PubMed1989

1H and 31P NMR measurement of cerebral lactate, high-energy phosphate levels, and pH in humans during voluntary hyperventilation: associated EEG, capnographic, and Doppler findings.

In order to explore the sensitivity of spatially resolved 1H and 31P NMR spectroscopy on a whole-body NMR instrument, cerebral metabolic changes in human volunteers were measured during hyperventilation provocation. During hyperventilation the flow velocity in the middle cerebral artery decreased significantly and the EEG showed a marked increase in slow activity. 1H NMR spectra revealed an increase in cerebral lactate concentration. 31P NMR spectra showed no changes in ATP or PCr peak heights, but a shift toward tissue alkalosis was derived from changes in Pi chemical shift. During subsequent recovery, lactate concentration decreased and a slight intracellular acidosis was detected. In three experiments broadening of the lactate resonance peak resulted in separation into two components at 1.32 and 1.48 ppm, in which the latter signal possibly arose from alanine.

Adult↗
PubMed1992

Effect of hyperventilation on oxygenation of the brain cortex of neonates.

A new phosphorescence imaging method (Rumsey et al, Science (1988) 1649) has been used to continuously monitor the oxygen pressure in the blood of the cerebral cortex of newborn pigs. The animals' blood pressure was continuously measured and PaCO2, PaO2 and arterial blood pH were measured periodically. The oxygen pressure in the blood was quantitatively determined for regions of about 100 um square within the image (from a total field of about 3 mm diameter). It was observed that during hyperventilation, which lowered PaCO2 and increased pH of the blood, oxygen pressure decreased in proportion to the decrease in PaCO2. For example, hyperventilation which decreased PaCO2 from its normal value of 40 Torr to 10 Torr caused a rapid (within 5 minutes) decrease in oxygen pressure in the blood of capillaries and veins to approximately 1/4 of normal.

Animals↗
PubMed1997

The effect of Dotarizine (Ca2+ channel blocker) on cerebral vessel reactivity in animals subjected to hyperventilation and anoxia.

Dotarizine--a novel piperazine derivative--belongs to wide spectrum Ca+ channel antagonists. It was reported to have strong vasodilatory and antiserotoninergic activities. Unlike other Ca+ channel blockers Dotarizine was found to have lower oral toxicity. In the presented study the influence of the oral administration of the novel compound on the blood flow velocity changes in different cerebral arteries--in basilar artery (BA) and middle cerebral artery (MCA)--was investigated under hyperventilation and hypoxic conditions of rabbits. In the first experimental group 25 mg/kg of Dotarizine dissolved in 0.25% agar was administered orally three times at the 10 hours' intervals. The sham group of animals was fed with agar of the same concentration. The results revealed that oral administration of Dotarizine diminished the vasoconstrictive effect of hyperventilation and this was more pronounced in MCA than in BA. During anoxic conditions stronger vasodilatory effects were observed in both groups of vessels and the low value of pulsatility index (PI) reflected pronounced decrease of the peripheral resistance, in comparison to the control group. Thus, the oral administration of Dotarizine decreases the peripheral resistance of cerebral vessels and therefore seems to have influence on the minute arteries of cerebrovascular system of the brain.

Animals↗
PubMed1992

Hyperventilation as the initial manifestation of lymphomatous meningitis.

We present the case of a 57 year old man who developed a B-cell lymphoma which involved his lymph nodes, liver, spleen, bone marrow, and peripheral blood. Shortly after attaining a complete remission with chemotherapy, the patient developed profound hyperventilation with no apparent cardiac or pulmonary cause. After one month, the patient developed a 7th nerve palsy and a subsequent work-up demonstrated that he had lymphomatous meningitis. The hyperventilation resolved completely with intrathecal chemotherapy, although the patient eventually died of widely disseminated lymphoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Mediation of serotonin-induced hyperventilation via 5-HT3-receptor in European eel Anguilla anguilla.

The effects of serotonin (5-hydroxytryptamine) on ventilation were investigated by continuous measurements of intrabuccal pressure in unrestrained eel. Intravenous administration of 5-hydroxytryptamine (30 micrograms.kg-1) caused a large increase in ventilatory frequency (+ 100%) and amplitude (+ 140%). The 5-hydroxytryptamine-induced hyperventilation was blocked by the 5-HT3-receptor antagonists metoclopramide (1.0 mg.kg-1) or MDL72222 (1.0 mg.kg-1), and was insensitive to the 5-HT1/2-receptor antagonist methysergide (3.0 mg.kg-1) and to the 5-HT4-receptor antagonist DAU 6285 CL (3.0 mg.kg-1). The hyperventilatory response to 5-hydroxytryptamine could be mimicked by the 5-HT3 receptor agonist 1-phenylbiguanide (300 micrograms.kg-1). These results strongly implicate the 5-HT3-receptor as the mediator of the 5-hydroxytryptamine-induced hyperventilation in eel.

Anguilla↗
PubMed1989

The hyperventilation-induced ischaemia model in human neuropharmacology: neurophysiological and psychometric studies of aniracetam and 3-OH aniracetam.

Standardized hyperventilation in young subjects induces changes in the EEG, a decrease in the velocity of the cerebral blood flow and a decline in cognitive performance, which are comparable to those occurring in patients with cerebral ischaemia. The anti-ischaemic properties of aniracetam and 3-OH aniracetam were tested in this model. A single oral dose of 3-OH aniracetam 1500 mg appeared to have the most pronounced effect on hyperventilation-induced EEG changes and cognitive deterioration. The test drugs had no effect on the heart rate or blood flow velocity. The effects agree with those of other drugs classified as noötropics.

Adult↗
PubMed1994

Hyperventilation-induced changes of blood cell counts depend on hypocapnia.

Voluntary hyperventilation for 20 min causes haemoconcentration and an increase of white blood cell and thrombocyte numbers. In this study, we investigated whether these changes depend on the changes of blood gases or on the muscle work of breathing. A group of 12 healthy medical students breathed 36 l.min-1 of air, or air with 5% CO2 for a period of 20 min. The partial pressure of CO2 decreased by 21.4 mmHg (2.85 kPa; P < 0.001) with air and by 4.1 mmHg (0.55 kPa; P < 0.005) with CO2 enriched air. This was accompanied by haemoconcentration of 8.9% with air (P < 0.01) and of 1.6% with CO2 enriched air (P < 0.05), an increase in the lymphocyte count of 42% with air (P < 0.001) and no change with CO2 enriched air, and an increase of the platelet number of 8.4% with air (P < 0.01) and no change with CO2 enriched air. The number of neutrophil granulocytes did not change during the experiments, but 75 min after deep breathing of air, band-formed neutrophils had increased by 82% (P < 0.025), whereas they were unchanged 75 min after the experiment with CO2 enriched air. Adrenaline and noradrenaline increased by 360% and 151% during the experiment with air, but remained unchanged with CO2 enriched air. It was concluded that the changes in the white blood cell and platelet counts and of the plasma catecholamine concentrations during and after voluntary hyperventilation for 20 min were consequences of marked hypocapnic alkalosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗