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Purpose of review Hyperventilation is commonly used in neurological patients to decrease elevated intracranial pressure (ICP) or relax a tense brain. However, the potentially deleterious effects of hyperventilation may limit its clinical application. The aim of this review is to summarize the physiological and outcome evidence related to hyperventilation in neurological patients. Recent findings Physiologically, hyperventilation may adversely decrease cerebral blood flow (CBF) and the match between the cerebral metabolic rate and CBF. In patients with severe traumatic brain injury (TBI), prolonged prophylactic hyperventilation with arterial carbon dioxide tension (PaCO2) less than 25 mmHg or during the first 24 h after injury is not recommended. Most patients (>90%) with an aneurysmal subarachnoid hemorrhage undergo hyperventilation (PaCO2

The significant improvements in both surgical techniques and anesthetic management for cardiac surgery have given millions of individuals who suffer from a life-threatening cardiovascular disease a new chance at life [1]. Although the overall perioperative mortality and morbidity has significantly reduced, neurological complications remain a major concern to this patient population [2,3]. Neurological complications secondary to cardiac surgery encompass a variety of disorders, including stroke, postoperative delirium (POD), and postoperative cognitive decline (POCD) [2,4]. The incidence of overt stroke (clinically symptomatic) ranges from 1.2 to 6%; whereas the covert stroke (clinically silent) detected by diffusion-weighed MRI occurs in as many as 50% of patients [5▪▪,6▪▪]. The reported incidence of POD ranges from 14 to 50% in cardiac surgical patients [2]; whereas POCD occurs in 25 to 50% of patients after cardiac surgery [2,5▪▪,7]. These neurological complications are associated with increased mortality, decreased quality of life and increased economic burden [4,8]. The cause of neurological complications is complex, elusive and likely multifactorial. Risk factors that are associated with various neurological complications include, but not limited to, age, history of previous stroke, preexisting cerebrovascular diseases, hypertension, atrial fibrillation, systemic inflammation, and surgical manipulation [6▪▪,9]. It should be noted that most of the risk factors, such as age and past medical history are not modifiable; whereas some factors, such as hypertension and atrial fibrillation, can be treated, optimized, and regarded as modifiable. The perioperative task is to intervene on those modifiable risk factors to further reduce neurological complications after cardiac surgery. In this review, we discuss those aspects in perioperative care that are modifiable and relevant to neurological complications after cardiac surgery based on the outcome evidence. Open in a separate window Box 1 no caption available