Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass

Abstract

To investigate the effects on cerebral perfusion by experimental venous congestion of the superior vena cava (SVC) during bicaval cardiopulmonary bypass (CPB) at 34 °C, pigs were subjected to SVC obstruction at levels of 75%, 50%, 25% and 0% of baseline SVC flow at two arterial flow levels (low, LQ, high, HQ). The cerebral perfusion was examined with near-infrared spectroscopy (NIRS), cerebral microdialysis and blood gas analysis. SVC obstruction caused significant decreases in the NIRS tissue oxygenation index (TOI) and in SVC oxygen saturations (P<0.05, both groups), while the mixed venous saturation was decreased only in the LQ group. Sagittal sinus venous saturations were measured in the HQ group and found significantly reduced in response to venous congestion (P<0.05). No microdialysis changes were seen at the group level, however, individual ischemic patterns in terms of concomitant venous desaturation, decreased TOI and increased lactate/pyruvate occurred in both groups. The total venous drainage remained stabile throughout the experiment, indicating increased flow in the inferior vena cava cannula. The results indicate that SVC congestion may impair cerebral perfusion especially in the case of compromised arterial flow during CPB. Reduced SVC cannula flow may pass undetected during bicaval CPB, if SVC flow is not specifically monitored.

Influence of Acute Jugular Vein Compression on the Cerebral Blood Flow Velocity, Pial Artery Pulsation and Width of Subarachnoid Space in Humans

“…The presented correlation may actually provide a link between cerebral venous insufficiency and cerebral arterial small vessel disease in human. Chronic cerebral insufficiency is associated with impaired cerebral perfusion [6], [32]. Toveda et al .…”

“…Acute superior vena cava occlusion results in increased pial venous pressure and subsequent blood-brain barrier disruption in rats [4]. Unilateral internal and external jugular vein ligation in swine increases bihemispheric cerebral blood flow and metabolism [5], and progressive superior vena cava obstruction produces measurable signs of impaired cerebral perfusion in pigs [6]. As cranial window installation and microscopic examination remain the methods of choice to investigate the pial microvessels in vivo [7], for obvious reasons, the effect of increased cerebral venous pressure has not yet been investigated in humans.…”

Reduced Cerebral Perfusion Pressure during Lung Transplant Surgery Is Associated with Risk, Duration, and Severity of Postoperative Delirium

“…Although MAP was held relatively constant and above autoregulatory thresholds (e.g., 50-150 mm Hg), it is possible that increased CVP due to surgical retraction resulted in lower cerebral perfusion pressure levels. For example, mechanistic studies in animal models have demonstrated that experimental venous obstruction of the superior vena cava results in significant decreases in cerebral perfusion (43), which may be alleviated through either pharmacologic intervention or partial obstruction relief (44). These findings suggest that future studies may benefit from examining potential treatment strategies to mitigate superior vena cava obstruction during lung transplant, as the presence of postoperative delirium has been shown to improve clinical outcomes following hospitalization (6,8,45).…”

Idiopathic sudden sensorineural hearing loss and ménière syndrome: The role of cerebral venous drainage

“…It could be hypothesised that when the bloodstream is not able to flow out the brain due to uncertain causes, the venous stasis could increase the hydrostatic pressure in the inner ear and the hearing and vestibular systems 24,25. Furthermore, the venous congestion could impair the cerebral perfusion when the arterial tree is already damaged: the impairment in venous drainage can induce ischaemic-like lesions due to the induced venous desaturation, the altered lactates/pyruvates ratio and the reduced tissue oxygenation index [26][27][28]. Such conditions are all able to worsen the functionality of the structures of the inner ear that are particularly susceptible to flow variations and oxygenations features of the blood.…”