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

In case of cranial trauma, early respiratory troubles either of central or peripheral origin often accelerate the deterioration of the neurological situation. The different values of PCO2, PO2, pH and alcaline reserve measured on samples of CSF in comatose patients prove the central acidosis related to metabolic and vascular disorders in the damaged areas. Our results confirm the correlation between the importance of this disturbances and the severity of the trauma. It is thus necessary to insure patients of satisfactory respiration conditions. The tracheobronchial cleansing is applicable to intubated or tracheotomized patients by an instillation of 5ml of simple or bicarbonated physiological serum 4 to 6 times a day, followed by repeated aspirations and associated to a preventive endotracheal instillation of 80 mg of Gentamycin 4 times a day. Moreover we use controlled respiration which does not modify the gazometric parameters in the CSF but which assures patients a normoxia and moderate hypocapnia with a decrease of intracranial hypertension. Treatment by controlled hyperventilation must be precocious, because the recuperation at the level of the damaged zones is very slow.
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PMID:Treatment of comatose patients by mechanical hyperventilation. 0 50

In a group of 21 cats, the middle cerebral artery pressure (MCAP) was recorded by means of a catheter introduced into the artery at its origin, just distal to the occlusion. The effects of hypertension, hypercapnia, and hypocapnia were studied. In a group of five cats, both middle cerebral arteries (MCA) were catherized and the pressure was recorded simultaneously on both sides. In another group of five cats, O2 tension measurements were made with the aid of oxygen electrodes in the brain tissue, the occluded MCA, and the common carotid artery. Some of the results obtained in this study are compared with the results of a previous study where monkeys were used as experimental animals.
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PMID:Haemodynamic changes in the cerebral circulation of the cat during occlusion of the middle cerebral artery. 10 Oct 24

Serial magnification angiography under hypocapnia and hypertension was performed in 200 cases of cerebral tumours and cerebrovascular lesions. The advantages over conventional angiography are evident; the extent of a tumour is easier to determine as well as in most cases the nature of the mass lesion.
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PMID:Serial magnification angiography under hypocapnia and hypertension. 20 8

The effects of induced hypocapnia, hypothermia, and hypertension were surveyed in a primate model of acute stroke during and following a 48-hour period of intensive care. The results were compared to a group of nine control animals previously studied. Hypocapnia (PaCO2=25 torr) was examined in five animals and did not appear to alter the expected mortality, degree of neurological deficit, or frequency of infarction. There was, however, a suggestion that the size of infarction may be reduced. Hypothermia (29 degrees C) in five animals had a detrimental effect in that no animals survived following the intensive care period and all had infarction with massive edema. We speculate that hypothermia caused a sufficient increase in blood viscosity as to compromise collateral flow, thereby accounting for this detrimental effect. Induced hypertension (to 20% above control levels) was abandoned after three animals because of severe systemic effects (cardiac failure and pulmonary edema) resulting in death during the period of intensive care.
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PMID:Failure of prolonged hypocapnia, hypothermia, or hypertension to favorably alter acute stroke in primates. 40 43

The effects of droperidol and fentanyl on the intracranial pressure (i.c.p.) and cerebral perfusion pressure (c.p.p.) were studied in eight anaesthetized normocapnic patients with intracranial space-occupying lesions. The infection of droperidol resulted in a small and not significant increase in i.c.p. from 24.0 to 27.2 mm Hg, while c.p.p. decreased from 75.9 mm Hg to 57.8 mm Hg, as a result of a decrease in systemic arterial pressure. The addition of fentanyl produced no change in i.c.p., but a further decrease in arterial pressure decreased c.p.p. from 60.4 mm Hg to 47.8 mm Hg. In four patients values of c.p.p. less than 40 mm Hg were obtained. C.p.p. was was increased by hyperventilation in all but one of these patients. It is concluded that droperidol and fentanyl should be used in patients with intracranial hypertension only if hypocapnia has been established and when the arterial pressure is normal or increased.
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PMID:The effects of droperidol and fentanyl on intracranial pressure and cerebral perfusion pressure in neurosurgical patients. 79 9

In 7 baboons and 5 macaques the effects of hypercapnia, hypocapnia, hypertension, and combinations of hypertension plus hypocapnia and of hypertension plus hypercapnia on the regional perfusion pressure (rPP) in the brain area rendered ischaemic by occlusion of the middle cerebral artery (MCA) were studied. A new technique for recording the pressure in the occluded MCA was used. The regional tissure pressure (rTP) was recorded with the so called wick type pressure transducers. Hypercapnia produced a marked decrease in rPP in the ischaemic brain area. Hypertension, especially in combination with hypocapnia, produced a very pronounced increase in rPP in the ischaemic brain area. The clinical implications of these findings are discussed. Occlusion of the homolateral common carotid artery (CCA) was followed by a very slight and transient drop in the occluded MCA pressure. Occlusion of the occluded MCA pressure.
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PMID:The influence of changes in arterial CO2 and blood pressure on the collateral circulation and the regional perfusion pressure in monkeys with occlusion of the middle cerebral artery. 81 1

In 7 baboons and 5 macaques the effects of hypercapnia, hypocapnia, hypertension, and combinations of hypertension plus hypocapnia and of hypertension plus hypercapnia on the regional perfusion pressure (rPP) in the brain area rendered ischaemic by occlusion of the middle cerebral artery (MCA) were studied. A new technique for recording the pressure in the occluded MCA was used. The regional tissue pressure (rTP) was recorded with the so called wick type pressure transducers. Hypercapnia produced a marked decrease in rPP in the ischaemic brain area. Hypertension, especially in combination with hypocapnia, produced a very pronounced increase in rPP in the ischaemic brain area. The clinical implications of these findings are discussed. Occlusion of the homolateral common carotid artery (CCA) was followed by a very slight and transient drop in the occluded MCA pressure. Occlusion of the contralateral CCA was followed by a marked and persistent drop in the occluded MCA pressure.
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PMID:The influence of changes in arterial CO2 and blood pressure on the collateral circulation and the regional perfusion pressure in monkeys with occlusion of the middle cerebral artery. 81 73

The concept that reflex control of cerebral vessels is unimportant has been challenged by recent studies which suggest that carotid baroreceptors have an important role in regulation of cerebral blood flow (CBF). In this study we have tested the hypothesis that arterial baroreceptors contribute to regulation of total or regional CBF. CBF was measured in anesthetized dogs with 15 mu microspheres. Stimulation of carotid baroreceptors, by raising carotid sinus pressure, did not alter or redistribute cerebral flow. Responses to baroreceptor stimulation were intact, as manifested by vasodilation in skeletal muscle. CBF decreased during systemic hypocapnia and increased during hypercapnia, which indicates that failure of cerebral flow to change during baroreceptor stimulation was not due to unresponsiveness of cerebral vessels. During hypercapnia, baroreceptor stimulation also failed to alter CBF. In other studies CBF was measured during increases in systemic arterial pressure, before and after denervation of arterial baroreceptors. Increases in arterial pressure did not increase CBF either before or after denervation of baroreceptors. We conclude that baroreceptor stimulation does not alter total or regional CBF and that baroreceptors do not regulate cerebral flow during systemic hypertension.
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PMID:Total and regional cerebral blood flow during stimulation of carotid baroreceptors. 94 13

Cerebral blood flow (CBF) was measured by a 133Xe inhalation technique in 8 patients with chronic high spinal cord injuries. Six patients had a physiologically complete cervical cord transection and 1 subject had an incomplete C4-5 lesion but with evidence of interruption of sympathetic pathways. CBF and arterial blood pressure (BP) were measured in the supine position and then in the sitting, or feet up, position to produce a change of BP. In 4 patients CBF was measured during a suction manoeuvre applied to the lower half of the body to produce a fall of BP. There was no significant change of CBF in the patients during hypo- and hypertension. The response of CBF to hyperventilation for 5 min was measured in the supine position and did not differ significantly from that of 13 normal "control" subjects and 1 patient with a lesion at T2-3. It is concluded that the responses of the cerebral circulation to change of blood pressure and to hypocapnia are normal in patients with high spinal cord transection. The mechanisms involved in these responses are therefore independent of control via cervical sympathetic pathways.
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PMID:The effect of hypocapnia and change of blood pressure on cerebral blood flow in men with cervical spinal cord transection. 97 19

By grouping patients who had carotid angiograms under unusually carefully monitored conditions it has been shown that hypocapnia is associated with vasodilation at low blood pressure but not at high blood pressure. The mechanism is discussed in general terms and it is suggested that the hypocapnic vasodilation may be a response to cerebral hypoxia and may be transmitted via an intracerebral autonomic pathway. Clinical and angiographical diagnoses are given for 50 patients.
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PMID:Paradoxical dilation of the large cerebral arteries in hypocapnia in man. 100 31


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