The effect on blood pressure in the sheep and calf of clamping some of the arteries contributing to the cephalic circulation

Abstract

In other studies utilizing a number of different techniques we have reported on the distribution of blood to the brain of the ox and sheep and concluded that cephalic blood flow in these species is controlled by physical haemodynamic equilibrium mechanisms (Baldwin, 1960; Baldwin & Bell, 1963 a, b). The work described here gives an account of the pressure changes which occur in the cranial circulation of the ox and sheep during disruption of blood flow to this area when occlusion of various combinations of the carotid, vertebral and occipital arteries is effected.Previous investigations reporting on pressure variations occurring in the cephalic vessels after clamping the common carotid arteries have usually been incidental to reflex responses following alteration of pressure within the carotid sinus (see Heymans & Neil, 1958). METHODSThe experimental and surgical procedures used on the twelve sheep and nine calves of these experiments were the same as those described in the preceding paper (Baldwin & Bell, 1963b).Cephalic blood pressure was measured bilaterally by cannulation of the proximal ends of the divided lingual arteries, and systemic blood pressure was recorded from the femoral artery. Mercury manometers were used, with 5 % sodium citrate as an anticoagulant in the manometer systems throughout the experiments. Respiration was recorded by a pneumograph and tambour. RESULTSThe sheep Effect of clamping one common carotid artery. Occlusion of one common carotid in the mid-cervical region produced an average fall of 31 % (range 22-40 %) in the pressure of the homolateral lingual artery. The fall * Present address:

Continuous Measurement of Scalp Tissue Oxygen Tension and Carotid Arterial Oxygen Tension in the Fetal Lamb

“…The occlusion of one of the carotid arteries, necessary for the continuous recording of arterial Pu , does not influence cerebral or scalp perfusion, because the sheep has an extensive system of intervascular con nections, as demonstrated by Baldwin and Bell (13). Fig.…”

Animal models for the assessment of novel vascular conduits

“…105 Occlusion of one or both CCAs causes increases in blood flow and pressure in the remaining CCA or vertebral arteries, or both. 106,107 Unilateral CCA occlusion is well tolerated, but temporary bilateral occlusion results in changes in the amplitude and frequency in the electroencephalogram of anesthetized sheep, or swaying and ataxia without loss of consciousness in awake sheep. Clamping both CCAs after previous ligation of both occipitovertebral anastomoses invariably results in abolition of the electroencephalogram, as does clamping of both external carotid arteries.…”

Sheep models for evaluation of novel patch and prosthesis material in vascular surgery: tips and tricks to avoid possible pitfalls

“…In contrast, implantation of grafts in the neck is well tolerated, with minimal postoperative morbidity. Neurologic complications resulting from either clamping during graft implantation or postoperative occlusion are rare due to vertebral arteries, which communicate with the distal common carotid artery through the occipito-vertebral anastomosis and due to the rete mirabilis, a dense network of blood vessels, which is situated high up in the middle of the cranium of the sheep [ 30 , 39 – 42 ]. Occlusion of one or both common carotid arteries causes a compensatory increase in blood flow in the contralateral common carotid artery and/or vertebral arteries [ 30 , 42 ].…”