Cardiac output changes after osmotic therapy in neurosurgical and neurocritical care patients: a systematic review of the clinical literature

Abstract

AIMOsmotherapy constitutes a first-line intervention for intracranial hypertension management. However, hyperosmolar solutes exert various systematic effects, among which their impact on systemic haemodynamics is poorly clarified. This review aims to appraise the clinical evidence of the effect of mannitol and hypertonic saline (HTS) on cardiac performance in neurosurgical and neurocritical care patients. METHODA database search was conducted to identify randomized clinical trials and observational studies reporting HTS or mannitol use in acute brain injury setting. The primary end-points were alterations of cardiac output (CO) and other haemodynamic variables, while the impact of osmotic agents on intracranial pressure, brain relaxation, plasma osmolality, electrolyte levels and urinary output constituted secondary outcomes. RESULTSEight studies, enrolling 182 patients in total, were included. HTS exerted a more profound cardiac output augmentation than mannitol, but no distinct difference between groups occurred. Central venous pressure, stroke volume and stroke volume variation were favourably affected by both osmotic agents, whilst the reported changes in blood pressure were inconclusive. HTS infusion yielded a larger intracranial pressure reduction than mannitol but had an equivalent effect on brain relaxation. Mannitol presented a more potent diuretic effect than HTS. Effect on serum osmolality was alike in both osmotic agents, but contrary to HTS-promoted hypernatraemia, mannitol use induced transient hyponatraemia. CONCLUSIONSMannitol or HTS administration seems to induce an enhancement of cardiac performance; being more prominent after HTS infusion. This effect combined with mannitol-induced enhancement of diuresis and HTS-promoted increase of plasma sodium concentration could partially explain the effects of osmotherapy on cerebral haemodynamics. British Journal of Clinical Pharmacology WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Osmotherapy with either mannitol or hypertonic saline (HTS) is the recommended first-line medical intervention for optimizing cerebral perfusion through brain relaxation.• Mannitol has long been used as osmotic agent for ensuring brain relaxation in neurosurgical patients undergoing craniotomy, but the clinical benefit of mannitol infusion in acute brain injury setting, has not yet been proven according to evidence-based medicine.• Recent guidelines suggest the use of HTS as a second-line therapy in case mannitol fails to reduce intracranial pressure, in patients sustaining traumatic brain injury. WHAT THIS STUDY ADDS• Both mannitol and HTS induce an increase in cardiac output, which is more pronounced after HTS than mannitol administration.• Mannitol and HTS infusion are associated with a trend towards to mean arterial pressure and heart rate reduction.• Both osmotic agents induced an intracranial pressure reduction and brain relaxation, an effect that seems to be more prominent in HTS-treated patients.

Monitoring Osmotherapy in Traumatic Brain Injury Patients: Correlation Between Ultrasound Assessment of Optic Nerve Sheath Diameter and Computed Tomography Scan

“…In follow up of vital data we found there was no statistically significant difference in BP, HR and temperature. This result agree with systematic review and meta-analysis done Tsaousi et al (10) to show cardiac output changes after osmotic therapy in neurosurgical and neurocritical care patients, and concluded that mannitol induced a consistent MAP deterioration, which became apparent immediately after the end of the infusion and lasted up to 45 min, and reported this effect was not of statistical importance and also in HR.…”

“…): ROC curve of Right ONSD before and after mannitol therapy as a predictor of brain edema (2): ROC curve of left ONSD before and after mannitol therapy as a predictor of brain edema Table(10): ROC curve of left ONSD before and after mannitol therapy as a predictor of brain edema…”

Comparison of Equiosmolar Doses of 7.5% Hypertonic Saline and 20% Mannitol on Cerebral Oxygenation Status and Release of Brain Injury Markers During Supratentorial Craniotomy: A Randomized Controlled Trial

“…Hyperosmolar therapy constitutes the mainstay of medical interventions to control increased intracranial pressure (ICP), irrespective of etiology 1–3. Currently, mannitol and hypertonic saline (HTS) are the hyperosmolar solutions most extensively used in neurosurgical and neurocritical care practice to attenuate the intensity and duration of intracranial hypertension and thus improve cerebral perfusion and oxygen delivery 4,5. In addition, during craniotomy, reduction of brain water content facilitates brain relaxation before dural opening, improves brain elastance, optimizes surgical exposure, and attenuates brain retractor pressure 3,6,7…”

“…[1][2][3] Currently, mannitol and hypertonic saline (HTS) are the hyperosmolar solutions most extensively used in neurosurgical and neurocritical care practice to attenuate the intensity and duration of intracranial hypertension and thus improve cerebral perfusion and oxygen delivery. 4,5 In addition, during craniotomy, reduction of brain water content facilitates brain relaxation before dural opening, improves brain elastance, optimizes surgical exposure, and attenuates brain retractor pressure. 3,6,7 HTS and mannitol share some common brain bulkreducing and ICP-lowering properties, among which the generation of osmotic fluid shifts, enhancement of cardiac output, improvement of capillary blood laminar flow, and dehydration of endothelial cells hold key roles.…”

“…5 HTS lacks diuretic properties and thus sustains volume expansion for a considerable time, whereas mannitol induces a profound diuresis, which can lead to hypovolemia and, in turn, could reduce brain perfusion and promote secondary cerebral insults. 3,5 Although animal studies indicate that HTS might also be more advantageous than mannitol in terms of attenuation of neuroinflammatory responses and improvements in cerebral tissue oxygenation, these properties have not been consistently reported in clinical studies. 12,13 To the best of authors' knowledge, there are no previous studies investigating the impact of HTS and mannitol-induced alterations in hemodynamics and brain bulk reduction on cerebral oxygenation status as a single integrated concept during craniotomy.…”