The influence of intraabdominal hypertension on the central nervous system: current insights and clinical recommendations, is it all in the head?

INTRODUCTION: Intra-abdominal hypertension (IAH) and abdominal compartment syndrome are a common occurrence in ICU patients. The deleterious effects of IAH on organ function are well known and increasingly appreciated in recent years, especially where renal and respiratory function are concerned. METHODS: This review will focus on the available literature from the last years.A Medline and PubMed search was performed in order to find an answer to the question "What is the impact of increased IAP on neurologic function in the critically ill?" RESULTS: The amount of data on the influence of IAH on the central nervous system is more scarce, but several animal and human studies have demonstrated a clear correlation between intra-abdominal pressure (IAP) and intracranial pressure (ICP). This correlation is probably due to transmission of the increased IAP to the thorax leading to increased intrathoracic, pleural pressure and central venous pressure, decreased venous return from the brain and increased ICP.This hypothesis is supported by the observation that the increase in ICP is abolished when a sternotomy and pleuropericardotomy are performed, and by the fact that abdominal decompression has produced good results in treating refractory intracranial hypertension (ICH) in patients with both IAH and ICH. CONCLUSIONS: A close relationship between IAP and ICP has been observed in several animal and human studies. The clinical impact of this association is dependent on the baseline ICP and the compensatory reserve of the patient. Some studies have reported good results in treating refractory ICH by abdominal decompression in patients with concomitant IAH. Monitoring of IAP and ICP in risk patients is essential.