Arterio-venous epidural shunting in epidural bleeding radiological and physiological characteristics. An experimental study in dogs

Habash, Alaa; Zwetnow, N. N.; Löfgren, Jan

doi:10.1007/bf01401431

Cited by 16 publications

(10 citation statements)

References 14 publications

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“…1. They are similar to results reported previously 11,12,16,26,41. In short the bleeding rate and haematoma volume increase was rapid at first and then slowed gradually.…”

Section: Intracranial Bleeding and The Course Of Intracranial Pressuressupporting

confidence: 92%

“…Blood gas measurements were taken immediately after each CBF measurement. Each animal served as its own control, according to a protocol previously described in several studies from this laboratory 11,12,16,35,36,41,42 The physiological changes observed during these experiments were not affected by changes in blood gases. The mean values for the 3 groups are shown in Table 1.…”

Section: Controlsmentioning

confidence: 99%

“…The growth of an epidural haematoma differs from such an infusion in two vital respects. Firstly volume loading during bleeding is rapid at first, subsequently decreasing exponentially 16,26. Secondly the loading is powered by the animal itself and not by an outside source.…”

Section: Introductionmentioning

confidence: 99%

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Cerebral blood flow during experimental epidural bleeding in swine

Ganz

Hall²,

Zwetnow³

1990

Acta neurochir

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Regional cerebral blood flow (rCBF) was studied during an aggressive epidural bleed, using a ventilated swine model. rCBF, regional organ blood flow and cardiac output were measured using the radioactive microsphere technique. Blood flows were measured prior to the start of bleeding (Stage 1), when intracranial pressures had reached a plateau and supratentorial perfusion pressure was reduced by about 50% (Stage 2), and at isoelectric EEG (Stage 3). Supratentorial rCBF did not change significantly between stages 1 and 2 while rCVR decreased, implying autoregulatory activity. Cerebral ischaemia developed between stages 2 and 3 when rCBF values fell to levels between 20 and 50% of control values. Infratentorial rCBF changes were similar but less marked, so that adequate brain stem perfusion was maintained below the upper mesencephalon. The left temporal and left parietal cortex and upper mesencephalon suffered a greater reduction in rCBF than other regions, due to proximity to the haematoma and tentorial herniation. The supratentorial perfusion pressure at stage 2 was 60 mm Hg associated with a haematoma volume of 6% of the intracranial volume (ICV). The infratentorial perfusion pressure never fell below 60 mm Hg. The Cushing response was absent when the EEG became isoelectric. This is tentatively ascribed to the absence of hypoxia, because mechanical ventilation was used. Instead systemic arterial hypotension accompanied bleeding in this ventilated model. This hypotension was due to falling cardiac output and peripheral vasodilation.

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“…1. They are similar to results reported previously 11,12,16,26,41. In short the bleeding rate and haematoma volume increase was rapid at first and then slowed gradually.…”

Section: Intracranial Bleeding and The Course Of Intracranial Pressuressupporting

confidence: 92%

Section: Controlsmentioning

confidence: 99%

See 1 more Smart Citation

Cerebral blood flow during experimental epidural bleeding in swine

Ganz

Hall²,

Zwetnow³

1990

Acta neurochir

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“…There were no abnormalities of PaO 2 PaCO2 or arterial pH in any of the groups and no significant difference between groups. Each animal was observed for 10 to 30 minutes after completion of the preparation, and in the case of spontaneously breathing animals following disconnection of the ventilator, according to a protocol used in many previous studies 9, 13,25,35,37,38 No systematic change occurred in any variable during this period.…”

Section: Control Testsmentioning

confidence: 99%

A quantitative study of some factors affecting the outcome of experimental epidural bleeding in swine

Ganz

Zwetnow²

1990

Acta neurochir

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During an experimentally induced aggressive epidural bleed the effect on outcome of haematoma volume, cerebral perfusion pressures, intracranial pressure gradients and ventilation were examined in a swine model. Two groups of experiments were performed using either spontaneous ventilation (group 1, n = 6) or mechanical ventilation for 1 hour (group 2, n = 7). The preparations were otherwise identical. An animal was considered to have succumbed when the EEG became irreversibly isoelectric within a total follow-up time of 80 minutes. Mechanical ventilation had a marked effect on survival. All spontaneously ventilated animals succumbed, 4 of them in less than 60 minutes, the remaining 2 between 60 and 80 minutes after the start of bleeding. All mechanically ventilated animals survived for the 60 minutes while the ventilator was connected. Following disconnection 2 animals started to breathe spontaneously and survived the final 20 minutes of the 80 minutes of the follow-up time. The remaining 5 succumbed following apnoea. The size of haematoma did not differ significantly between the groups. Two additional factors, hypoventilation and a secondary rise in supratentorial pressure, contributed to a lethal outcome. Hypoventilation was an inevitable precursor of the isoelectric EEG. There was a close correlation between the development of hypoventilation and intracranial herniation. A secondary rise in supratentorial pressure, unrelated to ventilation, was seen after cessation of bleeding in 8/13 cases. It was associated with a falling supratentorial perfusion pressure and EEG attenuation, suggesting a secondary intracranial expansion, possibly due to oedema, hydrocephalus or both. It is concluded that mechanical ventilation in the acute stage of epidural bleeding may be of clinical value.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…1 illustrates an experiment in a cat with an intracranial volume of 24.0 ml. The rate of balloon expansion was 1.00ml/minute, i.e., 4.17% of intracranial volume per minute. After the start of inflation, blood pressure, respiration and heart rate remained unchanged until the balloon volume had reached a size of 1.05 ml (4.4% of intracranial volume), when arterial pressure started to rise and the respiration frequency to diminish.…”

Section: Cats Group Imentioning

confidence: 99%

Effects of continuously expanding intracranial lesions on vital physiological parameters. An experimental animal study

1986

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The work described in this report confirms and extends the results described in a preliminary communication (Löfgren, J. and Zwetnow, N.N., Acta Neurol. Scand. (1970, 625) which examined the effects in cats of an expanding mass, in the form of an intracranial supratentorial balloon, on vital physiological parameters. In the present study, particular emphasis was placed on the possible significance of the rate of expansion of the mass in the range usually encountered in the clinical situation of intracranial haemorrhages. Results from the experiments on 37 cats and 8 dogs showed that changes in vital parameters appeared when the balloon had reached a volume of about 5% of the intracranial volume (the "reaction volume") while respiratory arrest occurred at an intracranial volume of about 10% (the "apnoea volume"). Both threshold volumes were independent of the rate of expansion within the range used. Alterations in EEG, heart rate, respiratory rate and systemic arterial pressure usually occurred simultaneously with the development of a transtentorial pressure gradient. When respiratory arrest occurred, the cerebral perfusion pressure was markedly reduced, usually to a value of about 30 mm Hg, suggesting that brain tissue ischaemia is an important component in the lethal mechanism underlying intracranial expanding lesions. It is proposed that the volume load tolerance of the organism towards an expanding intracranial lesion, as expressed by the reaction volume and the apnoea volume, may represent a biologically useful parameter potentially suitable for quantitative evaluation of adverse agents and therapeutic procedures.

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Arterio-venous epidural shunting in epidural bleeding radiological and physiological characteristics. An experimental study in dogs

Cited by 16 publications

References 14 publications

Cerebral blood flow during experimental epidural bleeding in swine

Cerebral blood flow during experimental epidural bleeding in swine

A quantitative study of some factors affecting the outcome of experimental epidural bleeding in swine

Effects of continuously expanding intracranial lesions on vital physiological parameters. An experimental animal study

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