Effects of lumbar myelography on subarachnoid pressure and cardiorespiratory parameters in healthy sheep

ABSTRACT: The purpose of this study was to evaluate the effects of lumbar myelography on subarachnoid pressure, cardiorespiratory parameters and pressure-volume index in sheep. Eight sheep were evaluated. The animals were submitted to puncture of the cisterna magna for monitoring of subarachnoid pressure (SaP). Lumbar myelography was performed through applying Iohexol (0.4mL/kg). ToC, PAS, PAD, MAP, InspISO, FeISO, SaP and CPP were recorded immediately after anesthetic stabilization (M0), during lumbar puncture (M1), and two, four and six minutes after contrast application (M2, M3 and M4, respectively). Blood pressure initially increased, then decreased, returning to basal level, similarly observed for InspISo and FeISo. The SaP rose initially thereafter remaining stable. Despite of the effect on subarachnoid pressure, lumbar myelography can be considered safe in sheep.

RESUMO: O objetivo foi avaliar os efeitos da mielografia lombar na pressão subaracnóidea, parâmetros cardiorrespiratórios e índice pressão-volume em ovinos. Oito ovelhas foram avaliadas. Os animais foram submetidos à punção da cisterna magna para monitoramento da pressão subaracnoidea (SaP). A mielografia lombar foi realizada com a aplicação de Iohexol (0,4mL/kg). Os momentos estudados foram: imediatamente após a estabilização anestésica (M0), durante a punção lombar (M1), dois, quatro e seis minutos após a aplicação do contraste (M2, M3 e M4, respectivamente), para avaliar as seguintes variáveis: ToC, PAS, PAD, MAP, InspISO, FeISO, Sap e CPP. A pressão arterial aumentou inicialmente, depois diminuiu, retornando aos valores iniciais, padrão também observado para o InspISo e o FeISo. O SaP subiu inicialmente, posteriormente, permanecendo estável. A mielografia lombar, apesar de influenciar a pressão subaracnoidea, pode ser considerada segura em ovinos.

Effects of lumbar myelography on subarachnoid pressure and cardiorespiratory parameters in healthy sheep / Efeitos da mielografia lombar na pressão subaracnoidea e nos parâmetros cardiorrespiratórios em ovelhas saudáveis

The purpose of this study was to evaluate the effects of lumbar myelography on subarachnoid pressure, cardiorespiratory parameters and pressure-volume index in sheep. Eight sheep were evaluated. The animals were submitted to puncture of the cisterna magna for monitoring of subarachnoid pressure (SaP). Lumbar myelography was performed through applying Iohexol (0.4mL/kg). ToC, PAS, PAD, MAP, InspISO, FeISO, SaP and CPP were recorded immediately after anesthetic stabilization (M0), during lumbar puncture (M1), and two, four and six minutes after contrast application (M2, M3 and M4, respectively). Blood pressure initially increased, then decreased, returning to basal level, similarly observed for InspISo and FeISo. The SaP rose initially thereafter remaining stable. Despite of the effect on subarachnoid pressure, lumbar myelography can be considered safe in sheep.(AU)

O objetivo foi avaliar os efeitos da mielografia lombar na pressão subaracnóidea, parâmetros cardiorrespiratórios e índice pressão-volume em ovinos. Oito ovelhas foram avaliadas. Os animais foram submetidos à punção da cisterna magna para monitoramento da pressão subaracnoidea (SaP). A mielografia lombar foi realizada com a aplicação de Iohexol (0,4mL/kg). Os momentos estudados foram: imediatamente após a estabilização anestésica (M0), durante a punção lombar (M1), dois, quatro e seis minutos após a aplicação do contraste (M2, M3 e M4, respectivamente), para avaliar as seguintes variáveis: ToC, PAS, PAD, MAP, InspISO, FeISO, Sap e CPP. A pressão arterial aumentou inicialmente, depois diminuiu, retornando aos valores iniciais, padrão também observado para o InspISo e o FeISo. O SaP subiu inicialmente, posteriormente, permanecendo estável. A mielografia lombar, apesar de influenciar a pressão subaracnoidea, pode ser considerada segura em ovinos.(AU)

Decending Regularity of Intra-abdominal Pressure / 医学研究杂志

Objective To explore the rat's abdominal pressure decending law by applying quantitative analytical technique.Methods Intra-abdominal hypertension rat model is made by Nitrogen aeroperitonerm.Nitrogen is exhausted the abdomen at fixed quantity and fixed time cell.MP-100A-CE type physiological monitor is used to record the changes of intra-abdominal pressure.The pressure numerical average value at different time are recorded,and the volume of Nitrogen exhausted and the pressure of intra-abdominal scatterplot are drawed.Regression analysis is used to study the functional relation between them.Results The regularity of the intra-abdominal pressure decrease was as follows:In Intra-abdominal Hypertension condition,discharge little Nitrogen could cause intra-abdominal pressure decrease greatly.Then the rate of decay is slowed.Intra-abdominal pressure(y)and Nitrogen in the abdomen(y)present decrement exponential function relation,the formula is:y=36.3190?0.9769x,and the pressure-volume index is-0.01.Conclusion Regularity of intra-abdominal pressure decengding is exponential function between intra-abdominal pressure and Nitrogen volume exhausted from the abdomen.

Effect on the Regional Cerebral Blood Flow and Biomechanical Factors in Ventricular Enlargement of Experimental Hydrocephalus

To evaluate the biomechanical changes and cerebral blood flow in hydrocephalic brain, this study was designed to determine the regional cerebral blood flow(rCBF; frontal cortex and periventricular area), the pressure volume index(PVI) and the resistance to the absorption of cerebrospinal fluid(Ro) in different stages of the kaolin-induced hydrocephalus. Fifty five 8 week-old cats, weighing 900g to 1300g were used in this experiment. The experimental animals were divided into 2 groups ; a normal control(5 cats), and kaolin-induced hydrocephalic groups(50 cats). The kaolin-induced 1,2,4,6 and 8 weeks hydrocephalic groups after intracisternal injection of the kaolin. The rCBF was measured by hydrogen clearance technique and the PVI and Ro were determined by the technique of bolus manipulation of CSF. A significant elevation of the intracranial pressure(ICP) was observed in 2 weeks after kaolin injection and peak value(ICP=10.2+/-0.9mmhg) was obtained in 4 weeks after Kaolin injection. The significant decrease in rCBF were revealed in both frontal cortex and periventricular area of kaolin-induced hydrocephalic cats. The PVI was significantly increased from the normal value 0.77+/-0.02ml to 1.60+/-0.16ml at 4 weeks after kaolin injection and increased to 2.12+/-0.34ml at 6 weeks after kaolin injection. Ro was significantly decreased from the normal value 90.6+/-1.3mmHg/ml/min to 36.8+/-4.3mmHg/ml/min at 4 weeks after kaolin injection and further decreased to 6.2+/-1.9mmHg/ml/min at 8 weeks after kaolin injection. In Hydrocephalic cats, the size of the ventricle(septum pellucidum-caudate nucleus distance) continued to increase in size up to 9.40+/-0.7mm at the 4th week. However, there was no further increase in ventricular size after the 4th week. This study indicated that kaolin-induced hydrocephalic cats led to dramatic changes in volume-buffering capacity expressed as PVI, coupled a reduction in the Ro. The absorptive defect and also loss of volume-buffering capacity are not sufficient to cause progressive ventricular enlargement. It is assuming that some microcirculatory impairment in the brain parenchyma is playing an important role which facilitates ventricular expansion with changes of biomechanical property of the brain.

An Experimental Study on the Effect of Measurement Parameters and Hydrocephalus on the Pressure Volume Index

To study the effect of measurement parameters and hydrocephalus on the pressure volume index(PVI), PVI study was performed in 5 normal and 5 kaolin-induced hydrocephalic cats. The effects of injection volume, speed, laterality and influence of increased intracranial pressure(ICP) in normal and hydrocephalic cats on the PVI value were evaluated. The results were as follows; 1) Larger injection volume, increased ICP by continuous infusion, and presence of ventriculomegaly made the PVI value significantly higher(p<0.01, p<0.001, p<0.05, respectively). 2) Rapid injection made the PVI value significantly lower(p<0.01). 3) Increase of ICP accentuated the effects of injection volume and speed significantly(p<0.01). 4) There was no difference between the PVI values measured with injection into the ipsilateral lateral ventricle and those measured with injection into the cantralateral lateral ventricle. 5) With the above results, it is considered advisable to perform the PVI study with constant injection volume, speed and ICP.