Brain Tissue Oxygen Monitoring and the Intersection of Brain and Lung: A Comprehensive Review

Abstract

SummaryTraumatic brain injury is a problem that affects millions of Americans yearly and for which there is no definitive treatment that improves outcome. Continuous brain tissue oxygen (P btO 2 ) monitoring is a complement to traditional brain monitoring techniques, such as intracranial pressure and cerebral perfusion pressure. P btO 2 monitoring has not yet become a clinical standard of care, due to several unresolved questions. In this review, we discuss the rationale and technology of P btO 2 monitoring. We review the literature, both historic and current, and show that continuous P btO 2 monitoring is feasible and useful in patient management. P btO 2 numbers reflect cerebral blood flow and oxygen diffusion. Thus, continuous monitoring of P btO 2 yields important information about both the brain and the lung. The preclinical and clinical studies demonstrating these findings are discussed. In this review, we demonstrate that patient management in a P btO 2 -directed fashion is not the sole answer to the problem of treating traumatic brain injury but is an important adjunct to the armamentarium of multimodal neuromonitoring.

Effects of moderate and severe hypocapnia on intracerebral perfusion and brain tissue oxygenation in piglets

“…29 Furthermore, low PtO 2 has been shown to be associated with poor outcome in brain-injured patients. 2 In conclusion, this animal model revealed reduced, invasively measured cerebral blood flow and brain tissue oxygenation and a systemic increase in blood lactate even during moderate hypocapnia. No changes in rSO 2, measured by NIRS, were detected, despite decreased brain tissue oxygenation and reduced cerebral blood flow.…”

“…However, PtO 2 has been shown to be a reliable marker of brain tissue perfusion and is considered to reflect the balance between oxygen delivery and demand at tissue level . Furthermore, low PtO 2 has been shown to be associated with poor outcome in brain‐injured patients …”

“…This is surprising, as NIRS monitoring has recently been recommended in identifying and preventing PCO 2 -induced cerebral hypo-and hyperperfusion. 18 The present study might have been underpowered to detect alterations in rSO 2 affected by contamination from extracranial tissues. 24 Therefore, the NIRS sensors in the present study were positioned on the basis of computer tomography images obtained from a previous experiment to be appropriate for brain tissue sampling.…”

“…Hypocapnia is a common event that has been reported to occur in 69% of neonates undergoing general anesthesia . Arterial carbon dioxide partial pressure (PaCO 2 ) influences cerebral autoregulation with hypocapnia, resulting in vasoconstriction and decreased cerebral blood flow (CBF) . Consequently, hypocapnia during anesthesia may considerably lower cerebral perfusion, potentially resulting in serious consequences for the developing brain .…”

Benefits of Early Tracheostomy in TBI Patients

“…The brain requires an uninterrupted supply of glucose and oxygen to maintain cellular viability and metabolism, consuming up to 20% of individual's total oxygen, with an average of cerebral metabolic rate of oxygen (CMRO 2 ) between 3 and 3.8 ml/100 g/min [38][39][40][41]. Brain metabolism represents the largest source of energy consumption in the human body, since neuronal activity is supported through the production of adenosine triphosphate (ATP), which consumes nearly 60% of oxygen [42,43].…”