Brain-Lung Crosstalk: Management of Concomitant Severe Acute Brain Injury and Acute Respiratory Distress Syndrome

Abstract

Purpose of review: To summarize pathophysiology, key conflicts, and therapeutic approaches in managing concomitant severe acute brain injury (SABI) and acute respiratory distress syndrome (ARDS).

Recent findings: ARDS is common in SABI and independently associated with worse outcomes in all SABI subtypes. Most landmark ARDS trials excluded patients with SABI, and evidence to guide decisions is limited in this population. Potential areas of conflict in the management of patients with both SABI and ARDS are (1) risk of intracranial pressure (ICP) elevation with high levels of positive end-expiratory pressure (PEEP), permissive hypercapnia due to lung protective ventilation (LPV), or prone ventilation; (2) balancing a conservative fluid management strategy with ensuring adequate cerebral perfusion, particularly in patients with symptomatic vasospasm or impaired cerebrovascular blood flow; and (3) uncertainty about the benefit and harm of corticosteroids in this population, with a mortality benefit in ARDS, increased mortality shown in TBI, and conflicting data in other SABI subtypes. Also, the widely adapted partial pressure of oxygen (P_aO₂) target of > 55 mmHg for ARDS may exacerbate secondary brain injury, and recent guidelines recommend higher goals of 80-120 mmHg in SABI. Distinct pathophysiology and trajectories among different SABI subtypes need to be considered.

Summary: The management of SABI with ARDS is highly complex, and conventional ARDS management strategies may result in increased ICP and decreased cerebral perfusion. A crucial aspect of concurrent management is to recognize the risk of secondary brain injury in the individual patient, monitor with vigilance, and adjust management during critical time windows. The care of these patients requires meticulous attention to oxygenation and ventilation, hemodynamics, temperature management, and the neurological exam. LPV and prone ventilation should be utilized, and supplemented with invasive ICP monitoring if there is concern for cerebral edema and increased ICP. PEEP titration should be deliberate, involving measures of hemodynamic, pulmonary, and brain physiology. Serial volume status assessments should be performed in SABI and ARDS, and fluid management should be individualized based on measures of brain perfusion, the neurological exam, and cardiopulmonary status. More research is needed to define risks and benefits in corticosteroids in this population.

Keywords: Acute ischemic stroke; Acute lung injury; Acute respiratory distress syndrome; Cardiac arrest; Hypoxemic ischemic encephalopathy; Intracranial hemorrhage; Severe acute brain injury; Subarachnoid hemorrhage; Traumatic brain injury.

Fig. 1

Pathophysiological interactions between the brain and lungs

Fig. 2

Conflicts of ARDS management principles in SABI. Red boxes: potential conflicts, green boxes: management strategies. AC anticoagulation, ARDS acute respiratory distress syndrome, CBF cerebral blood flow, CPP cerebral perfusion pressure, ICP intracranial pressure, ITP intrathoracic pressure, MAP mean arterial pressure, NMB neuromuscular blockade, P_aO₂ partial pressure of oxygen, P_aCO₂ partial pressure of carbon dioxide, PbtO₂ brain tissue oxygen, pECLA pumpless extracorporeal lung assist, PEEP positive end-expiratory pressure, RAP right atrial pressure, TBI traumatic brain injury.

Fig. 3

Treatment algorithm for concomitant ARDS and SABI. ARDS acute respiratory distress syndrome, AED antiepileptic drug, cEEG continuous electroencephalogram, CPP cerebral perfusion pressure, CT computed tomography, CVC central venous catheter, ECMO extracorporeal membrane oxygenation, GCS Glasgow Coma Scale, HD hemodialysis, ICP intracranial pressure, MAP mean arterial pressure, NCSE non-convulsive status epilepticus, NCSz non-convulsive seizures, P_aO₂ partial pressure of oxygen, P_aCO₂ partial pressure of carbon dioxide, PbtO₂ brain tissue oxygen, PEEP positive end-expiratory pressure, RM recruitment maneuver, SABI severe acute brain injury, TBI traumatic brain injury, TCD transcranial Doppler, SE status epilepticus.