Hypertonic saline in critical care: a review of the literature and guidelines for use in hypotensive states and raised intracranial pressure

Safety and Effect on Intracranial Pressure of 3% Hypertonic Saline Bolus Via Peripheral Intravenous Catheter for Neurological Emergencies

BACKGROUND

Elevated intracranial pressure (ICP) is a neurological emergency in patients with acute brain injuries. Such a state requires immediate and effective interventions to prevent potential neurological deterioration. Current clinical guidelines recommend hypertonic saline (HTS) and mannitol as first-line therapeutic agents. Notably, HTS is conventionally administered through central venous catheters (CVCs), which may introduce delays in treatment due to the complexities associated with CVC placement. These delays can critically affect patient outcomes, necessitating the exploration of more rapid therapeutic avenues. This study aimed to investigate the safety and effect on ICP of administering rapid boluses of 3% HTS via peripheral intravenous (PIV) catheters.

METHODS

A retrospective cohort study was performed on patients admitted to Sisters of Saint Mary Health Saint Louis University Hospital from March 2019 to September 2022 who received at least one 3% HTS bolus via PIV at a rate of 999 mL/hour for neurological emergencies. Outcomes assessed included complications related to 3% HTS bolus and its effect on ICP.

RESULTS

Of 216 3% HTS boluses administered in 124 patients, complications occurred in 8 administrations (3.7%). Pain at the injection site (4 administrations; 1.9%) and thrombophlebitis (3 administrations; 1.4%) were most common. The median ICP reduced by 6 mm Hg after 3% HTS bolus administration (p < 0.001).

CONCLUSIONS

Rapid bolus administration of 3% HTS via PIV catheters presents itself as a relatively safe approach to treat neurological emergencies. Its implementation could provide an invaluable alternative to the traditional CVC-based administration, potentially minimizing CVC-associated complications and expediting life-saving interventions for patients with neurological emergencies, especially in the field and emergency department settings.

Effect of Hypertonic Saline Solution on the Ventilatory Mechanics of Lungs Donated After Brain Death

INTRODUCTION

Brain death (BD) compromises the viability of the lung for donation. Hypertonic saline solution (HSS) induces rapid intravascular volume expansion and immunomodulatory action. We investigated its role in ventilatory mechanics (VMs) and in the inflammatory activity of the lungs of rats subjected to BD.

METHODS

Wistar rats were divided into four groups: control, n = 10: intact rats subjected to extraction of the heart-lung block; BD, n = 8 (BD): rats treated with isotonic saline solution (4 mL/kg) immediately after BD; hypertonic saline 0 h, n = 9 (Hip.0'): rats treated with HSS (4 mL/kg) immediately after BD; and hypertonic saline 1 h, n = 9 (Hip.60'), rats treated with HSS (4 mL/kg) 60 min after BD. The hemodynamic characteristics, gas exchange, VMs, inflammatory mediators, and histopathological evaluation of the lung were evaluated over 240 min of BD.

RESULTS

In VMs, we observed increased airway resistance, tissue resistance, tissue elastance, and respiratory system compliance in the BD group (P < 0.037), while the treated groups showed no impairment over time (P > 0.05). In the histological analysis, the BD group showed a greater area of perivascular edema and a higher neutrophil count than the control group and the Hip.60' group (P < 0.05).

CONCLUSIONS

Treatment with HSS was effective in preventing changes in the elastic and resistive pulmonary components, keeping them at baseline levels. Late treatment reduced perivascular and neutrophilic edema in lung tissue.

Evaluation of the Safety of Slow IV Push Versus Slow IV Infusion Administration of 23.4% Sodium Chloride

Background and Purpose

Increased intracranial pressure due to cerebral edema is a medical emergency in which 23.4% sodium chloride (23.4% NaCl) may be a lifesaving intervention. Currently, safety data is limited on slow IV push (IVP) administration. The purpose of this study was to evaluate the safety of IVP administration of 23.4% NaCl and determine the number of infusion-related adverse events (IRAEs) compared to slow IV infusion (SIV) administration.

Methods

We performed a retrospective review of patients who received a dose of 23.4% NaCl at the (removed institution) from January 2015 to June 2020 as either SIV over 30 minutes or IVP over 2-5 minutes.

Results

In total, 81 patients, 55 in the IVP group and 26 in the SIV group, were included in the analysis. There was a significantly faster time from order entry to dose completion (IVP 25 [13,58] vs SIV 73 [55,113] minutes, P < .001). There was no difference in IRAEs between the groups (IVP 17 [31%] vs SIV 6 [23%], P = .466). Hypotension was most common (IVP 13 [24%] vs SIV 5 [19%], P = .656) followed by bradycardia (IVP 6 [11%] vs SIV 1 [4%], P = .291). There were no extravasations reported.

Conclusions

Overall, among a cohort of patients with cerebral edema, we found no difference in the incidence of IRAEs between SIV and IVP administration of 23.4% NaCl, and found a faster time to complete administration fssor the latter. In emergent scenarios where time may impact neurologic function, 23.4% NaCl administered IVP may be an alternative to SIV administration.

Hypertonic Saline Versus Other Intracranial-Pressure-Lowering Agents for Patients with Acute Traumatic Brain Injury: A Systematic Review and Meta-analysis

Acute traumatic brain injury (TBI) is a major cause of mortality and disability worldwide. Intracranial pressure (ICP)-lowering is a critical management priority in patients with moderate to severe acute TBI. We aimed to evaluate the clinical efficacy and safety of hypertonic saline (HTS) versus other ICP-lowering agents in patients with TBI. We conducted a systematic search from 2000 onward for randomized controlled trials (RCTs) comparing HTS vs. other ICP-lowering agents in patients with TBI of all ages. The primary outcome was the Glasgow Outcome Scale (GOS) score at 6 months (PROSPERO CRD42022324370). Ten RCTs (760 patients) were included. Six RCTs were included in the quantitative analysis. There was no evidence of an effect of HTS on the GOS score (favorable vs. unfavorable) compared with other agents (risk ratio [RR] 0.82, 95% confidence interval [CI] 0.48-1.40; n = 406; 2 RCTs). There was no evidence of an effect of HTS on all-cause mortality (RR 0.96, 95% CI 0.60-1.55; n = 486; 5 RCTs) or total length of stay (RR 2.36, 95% CI - 0.53 to 5.25; n = 89; 3 RCTs). HTS was associated with adverse hypernatremia compared with other agents (RR 2.13, 95% CI 1.09-4.17; n = 386; 2 RCTs). The point estimate favored a reduction in uncontrolled ICP with HTS, but this was not statistically significant (RR 0.52, 95% CI 0.26-1.04; n = 423; 3 RCTs). Most included RCTs were at unclear or high risk of bias because of lack of blinding, incomplete outcome data, and selective reporting. We found no evidence of an effect of HTS on clinically important outcomes and that HTS is associated with adverse hypernatremia. The included evidence was of low to very low certainty, but ongoing RCTs may help to the reduce this uncertainty. In addition, heterogeneity in GOS score reporting reflects the need for a standardized TBI core outcome set.

Use of a Novel Buffered Hypertonic Saline Solution for Fluid Replacement and Resuscitation During Spinal Surgery in Adolescents

Background

During major orthopedic procedures, such as posterior spinal fusion (PSF), isotonic fluids, colloids, starches, or gelatins are commonly used to replace the preoperative fluid deficit and provide ongoing fluid resuscitation. Given recent concerns regarding the potential adverse physiologic effects of albumin solutions, we have modified our intraoperative practice to include the use of a novel 2% buffered hypertonic saline solution during major orthopedic procedures. We present our preliminary clinical experience with this novel fluid for intraoperative resuscitation and its impact on limiting the use of 5% albumin.

Methods

A retrospective review was performed to identify patients who received 2% buffered hypertonic saline during PSF. The intraoperative course of these patients was compared to case-matched control patients who received standard care with isotonic fluids plus 5% albumin as an adjunct for intravascular resuscitation.

Results

The study cohort included 23 patients who received 2% buffered hypertonic saline and 25 in the case-matched control group. There was no difference in the volume of intraoperative isotonic crystalloid fluids, estimated blood loss, and urine output between the two groups. In the control cohort, 19 of 25 patients (76%) received 5% albumin compared to only six of 23 patients (26%, P = 0.0005) in the 2% buffered hypertonic saline group. The final pH was higher in the patients that received 2% buffered hypertonic saline than in the control group (7.40 ± 0.03 versus 7.36 ± 0.06, P = 0.0131). Additionally, the starting and final serum sodium values were higher in the patients that received 2% buffered hypertonic saline, although no difference was noted in the mean change from the starting value (average increase of 2 mEq/L in both groups).

Conclusion

Use of a novel 2% buffered hypertonic saline solution for intraoperative resuscitation during major orthopedic procedures decreases the need for 5% albumin while avoiding the development of hyperchloremic metabolic acidosis which may occur with standard sodium chloride solutions.

Comparison of 20% mannitol and 3% hypertonic saline for intraoperative brain relaxation during supratentorial brain tumour craniotomy in patients with a midline shift

PURPOSE OF THE STUDY

A prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 20% mannitol and 3% hypertonic saline (HS) during elective supratentorial brain tumour surgery in patients with midline shift.

MATERIAL AND METHODS

Sixty patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 5mL/kg of 20% mannitol (n=30) or 3% HS (n=30) administered at skin incision. PCO2 in arterial blood was maintained within 35-40mmHg and arterial blood pressure was controlled within baseline values ±20%. The primary outcome was the proportion of satisfactory brain relaxation. The surgeon assessed brain relaxation on a four-point scale (1=excellent with no swelling, 2=minimal swelling, 3=serious swelling not requiring treatment, 4=severe swelling requiring treatment). Postsurgical intracranial changes determined by imaging techniques, postoperative complications, PACU and hospital stay, and mortality at 30 days were also recorded. Appropriate statistical tests were used for comparison; P<0.05 was considered as significant. This trial was registered in Eudract.ema.europa.eu (#2021-006290-40).

RESULTS

There was no difference in brain relaxation: 2.00 [1.00-2.00] and 2.00 [1.75-3.00] for patients in mannitol and HS groups, respectively (P=0.804). Tumour size (OR: 0.99, 95% CI: 0.99-1.01; P=0.371), peritumoral oedema classification (OR: 0.57, 95% CI: 0.11-2.84; P=0.493), mass effect (OR: 0.86, 95% CI: 0.16-4.87; P=0.864), anaesthesia (OR: 4.88, 95% CI: 0.82-28.96; P=0.081) and midline shift (OR: 5.00, 95% CI: 0.84-29.70; P=0.077) did not have a significant influence on brain swelling in patients treated with either mannitol or HS. No significant differences in perioperative outcomes, mortality and length of PACU and hospital stay were observed.

CONCLUSIONS

5mL/kg of 20% mannitol or 3% HS result in similar brain relaxation scores in patients undergoing craniotomy for supratentorial brain tumour with midline shift.

Safety of peripheral 3% hypertonic saline bolus administration for neurologic emergency

BACKGROUND/OBJECTIVE

Hypertonic sodium chloride (HTS) is used for emergent treatment of acute cerebral edema and other neurologic emergencies. Central access is not commonly available in emergent situations and 3% HTS is utilized peripherally. Many studies have shown the safety of its administration at rates up to 75 mL/h, but there is a lack of data to establish the safety of peripherally administered, rapid bolus dosing in emergent situations. The objective of this study is to describe the safety of rapid, peripherally administered (≥ 250 mL/h) 3% HTS for neurologic emergencies.

METHODS

This is a retrospective, cohort study including adult patients receiving 3% HTS via a peripheral IV site for elevated intracranial pressure, cerebral edema, or other neurological emergencies at a rate of at least 250 m/h between May 5, 2018 - September 30, 2021. Patients were excluded if they simultaneously received another hypertonic saline fluid. Baseline characteristics collected included HTS dose, rate and site of administration, indication for use and patient demographics. The primary safety outcome was incidence of extravasation and phlebitis within one hour of HTS administration.

RESULTS

There were 206 patients receiving 3% HTS who were screened, and 37 patients met inclusion criteria. The most common reason for exclusion was administration at a rate < 250 m/h. The median age was 60 (IQR 45, 72) with 51.4% being male. The most common indications for HTS were traumatic brain injury (45.9%) and intracranial hemorrhage (37.8%). The most common administration location was the emergency department (78.4%). The median IV-gauge (n = 29) was 18 (IQR 18, 20), with the most common placement site being antecubital (48.6%). The median dose of HTS was 250 mL (IQR 250, 350), with a median administration rate of 760 mL/h (IQR 500, 999). There were no episodes of extravasation or phlebitis noted.

CONCLUSIONS

Rapid, peripheral administration of 3% HTS boluses is a safe alternative for treatment of neurologic emergencies. Administration at rates up to 999 mL/h did not result in extravasation or phlebitis.

Management of noncytotoxic extravasation injuries: A focused update on medications, treatment strategies, and peripheral administration of vasopressors and hypertonic saline

Extravasation is the leakage of intravenous solutions into surrounding tissues, which can be influenced by drug properties, infusion techniques, and patient-related risk factors. Although peripheral administration of vesicants may increase the risk of extravasation injuries, the time and resources required for central venous catheter placement may delay administration of time-sensitive therapies. Recent literature gathered from the growing use of peripheral vasopressors and hypertonic sodium suggests low risk of harm for initiating these emergent therapies peripherally, which may prevent delays and improve patient outcomes. Physiochemical causes of tissue injury include vasoconstriction, pH-mediated, osmolar-mediated, and cytotoxic mechanisms of extravasation injuries. Acidic agents, such as promethazine, amiodarone, and vancomycin, may cause edema, sloughing, and necrosis secondary to cellular desiccation. Alternatively, basic agents, such as phenytoin and acyclovir, may be more caustic due to deeper tissue penetration of the dissociated hydroxide ions. Osmotically active agents cause cellular damage as a result of osmotic shifts across cellular membranes in addition to agent-specific toxicities, such as calcium-induced vasoconstriction and calcifications or arginine-induced leakage of potassium causing apoptosis. A new category has been proposed to identify absorption-refractory mechanisms of injury in which agents such as propofol and lipids may persist in the extravasated space and cause necrosis or compartment syndrome. Pharmacological antidotes may be useful in select extravasations but requires prompt recognition and frequently complex administration strategies. Historically, intradermal phentolamine has been the preferred agent for vasopressor extravasations, but frequent supply shortages have led to the emergence of terbutaline, a β2 -agonist, as an acceptable alternative treatment option. For hyperosmolar and pH-related mechanisms of injuries, hyaluronidase is most commonly used to facilitate absorption and dispersion of injected agents. However, extravasation management is largely supportive and requires a protocolized multidisciplinary approach for early detection, treatment, and timely surgical referral when required to minimize adverse events.

Glymphatic-assisted perivascular brain delivery of intrathecal small gold nanoparticles

Nanoparticles are ultrafine particulate matter having considerable potential for treatment of central nervous system (CNS) disorders. Despite their tiny size, the blood-brain barrier (BBB) restricts their access to the CNS. Their direct cerebrospinal fluid (CSF) administration bypasses the BBB endothelium, but still fails to give adequate brain uptake. We present a novel approach for efficient CNS delivery of ¹¹¹In-radiolabelled gold nanoparticles (AuNPs; 10-15 nm) via intra-cisterna magna administration, with tracking by SPECT imaging. To accelerate CSF brain influx, we administered AuNPs intracisternally in conjunction with systemic hypertonic saline, which dramatically increased the parenchymal AuNP uptake, especially in deep brain regions. AuNPs entered the CNS along periarterial spaces as visualized by MRI of gadolinium-labelled AuNPs and were cleared from brain within 24 h and excreted through the kidneys. Thus, the glymphatic-assisted perivascular network augment by systemic hypertonic saline is a pathway for highly efficient brain-wide distribution of small AuNPs.

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

BACKGROUND

Hyperosmolar therapy is the mainstay of treatment to reduce brain bulk and optimize surgical exposure during craniotomy. This study investigated the effect of equiosmolar doses of 7.5% hypertonic saline (HTS) and 20% mannitol on intraoperative cerebral oxygenation and metabolic status, systemic hemodynamics, brain relaxation, markers of cerebral injury, and perioperative craniotomy outcomes.

METHODS

A total of 51 patients undergoing elective supratentorial craniotomy were randomly assigned to receive 7.5% HTS (2 mL/kg) or 20% mannitol (4.6 mL/kg) at scalp incision. Intraoperative arterial and jugular bulb blood samples were collected at predefined time intervals for assessment of various indices of cerebral oxygenation; multiple hemodynamic variables were concomitantly recorded. S100B protein and neuron-specific enolase levels were determined at baseline, and at 6 and 12 hours after surgery for assessment of neuronal injury. Brain relaxation and perioperative outcomes were also assessed.

RESULTS

Demographic and intraoperative data, brain relaxation score, and perioperative outcomes were comparable between groups. Jugular bulb oxygen saturation and partial pressure of oxygen, arterial-jugular oxygen and carbon dioxide differences, and brain oxygen extraction ratio were favorably affected by 7.5% HTS up to 240 minutes postinfusion ( P <0.05), whereas mannitol was associated with only a short-lived (up to 15 min) improvement of these indices ( P <0.05). The changes in cerebral oxygenation corresponded to transient expansion of intravascular volume and improvements of cardiovascular performance. Increases in S100B and neuron-specific enolase levels at 6 and 12 hours after surgery ( P <0.0001) were comparable between groups.

CONCLUSIONS

The conclusion is that 7.5% HTS has a more beneficial effect on cerebral oxygenation than an equiosmolar dose of 20% mannitol during supratentorial craniotomy, yet no clear-cut clinical superiority of either solution could be demonstrated.

Equiosmolar doses of hypertonic saline versus mannitol for brain relaxation in patients undergoing elective craniotomies: an updated systematic review and meta-analysis

Background

Hypertonic saline and mannitol are hyperosmolar agents frequently used to lower ICP and relax the brain during surgeries. Several methods have been used to achieve a good and relaxed brain, such as hyperventilation, cerebrospinal fluid drainage, head position correction, and administration of hyperosmolar agents. Comparing equiosmolar doses between hypertonic saline and mannitol in patients undergoing elective craniotomies is important to further notice the differences in several outcomes. This study aims to compare the outcome of hypertonic saline versus mannitol on brain relaxation in patients undergoing elective craniotomy.

Results

10 articles from 2007 to 2021 were included. Hypertonic saline is associated with better brain relaxation (OR  = 1.84, 95% CI 1.31–2.59; P = 0.001) but significantly increase blood natrium level, both serum and arterial (MD = 3.03, 95% CI 1.70–4.36; P =  < 0.001 and MD = 7.14, 95% CI 0.04–14.24; P =  < 0.001, respectively). Mannitol was associated with increased fluid input and urine output (SMD = − 0.56, 95% CI − 0.98 to − 0.15; P =  < 0.001 and SMD = − 0.96, 95% CI − 1.42 to − 0.50; P =  < 0.001, respectively). Serum osmolality and hemodynamic parameters difference was insignificant.

Conclusions

Hypertonic saline is associated with significantly better brain relaxation score and increased blood sodium level without increase in urine. This may prove to be clinically significant in patients with electrolyte imbalance.

Hypertonic saline for traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Traumatic brain injury (TBI) causes mortality and long-term disability among young adults and imposes a notable cost on the healthcare system. In addition to the first physical hit, secondary injury, which is associated with increased intracranial pressure (ICP), is defined as biochemical, cellular, and physiological changes after the physical injury. Mannitol and Hypertonic saline (HTS) are the treatment bases for elevated ICP in TBI. This systematic review and meta-analysis evaluates the effectiveness of HTS in the management of patients with TBI.

METHODS

This study was conducted following the Joanna Briggs Institute (JBI) methods and PRISMA statement. A systematic search was performed through six databases in February 2022, to find studies that evaluated the effects of HTS, on increased ICP. Meta-analysis was performed using comprehensive meta-analysis (CMA).

RESULTS

Out of 1321 results, 8 studies were included in the systematic review, and 3 of them were included in the quantitative synthesis. The results of the meta-analysis reached a 35.9% (95% CI 15.0-56.9) reduction in ICP in TBI patients receiving HTS, with no significant risk of publication bias (t-value = 0.38, df = 2, p-value = 0.73). The most common source of bias in our included studies was the transparency of blinding methods for both patients and outcome assessors.

CONCLUSION

HTS can significantly reduce the ICP, which may prevent secondary injury. Also, based on the available evidence, HTS has relatively similar efficacy to Mannitol, which is considered the gold standard therapy for TBI, in boosting patients' neurological condition and reducing mortality rates.

Medical management of cerebral edema in large hemispheric infarcts

Acute ischemic stroke confers a high burden of morbidity and mortality globally. Occlusion of large vessels of the anterior circulation, namely the intracranial carotid artery and middle cerebral artery, can result in large hemispheric stroke in ~8% of these patients. Edema from stroke can result in a cascade effect leading to local compression of capillary perfusion, increased stroke burden, elevated intracranial pressure, herniation and death. Mortality from large hemispheric stroke is generally high and surgical intervention may reduce mortality and improve good outcomes in select patients. For those patients who are not eligible candidates for surgical decompression either due timing, medical co-morbidities, or patient and family preferences, the mainstay of medical management for cerebral edema is hyperosmolar therapy. Other neuroprotectants for cerebral edema such as glibenclamide are under investigation. This review will discuss current guidelines and evidence for medical management of cerebral edema in large hemispheric stroke as well as discuss important neuromonitoring and critical care management targeted at reducing morbidity and mortality for these patients.

Safety and Tolerability of 23.4% Hypertonic Saline Administered Over 2 to 5 Minutes for the Treatment of Cerebral Herniation and Intracranial Pressure Elevation

BACKGROUND

Hyperosmolar therapy is the cornerstone of medical management of sustained elevated intracranial pressure from cerebral edema. Acute intracranial hypertension and herniation is a medical emergency that requires rapid treatment and stabilization to prevent secondary brain injury or death. Intravenous hypertonic sodium chloride (NaCl) 23.4% is an effective treatment modality commonly used in this setting. Because of its high osmolarity, use has historically been limited primarily to central venous line administration as an intermittent infusion due to concerns about thrombophlebitis, injection site pain, and tissue necrosis or injury with extravasation. The objective of this analysis was to prospectively evaluate the safety of administration of 23.4% NaCl as a rapid intravenous push over 2-5 min.

METHODS

A prospective analysis of patients admitted between April 2021 and December 2021 who received 23.4% NaCl intravenous push over 2-5 min in a central or peripheral line was performed. Safety end points included incidence of new onset hypotension [defined as systolic blood pressure (SBP) < 90 mm Hg or SBP decrease of at least 20 mm Hg], bradycardia (defined as heart rate < 50 beats per minute), and infusion site reactions documented within 1 h of administration. For secondary safety outcomes, highest and lowest SBP and lowest heart rates documented within 1 h before 23.4% NaCl administration were compared with values collected within 1 h post administration and evaluated by mixed-design analysis of variance test with adjustment for peripheral versus central line administration.

RESULTS

We identified 32 patients who received 79 administrations of 23.4% NaCl through a central line or peripheral line during the study period. An SBP decrease of at least 20 mm Hg was observed in 13% of patients, an SBP < 90 mm Hg occurred in 16% of patients, and bradycardia occurred in 3% of patients who received 23.4% NaCl. Injection site pain was reported by one patient without documented thrombophlebitis, cellulitis, or tissue damage. Pain was not reported during two subsequent administrations in the same patient. There was no documented occurrence of soft tissue injury or necrosis in any patient. Compared with baseline vital signs before 23.4% NaCl administration, no difference in vital signs post administration was observed.

CONCLUSIONS

Central and peripheral administration of 23.4% NaCl over 2-5 min was well tolerated, and incidence of hypotension, bradycardia, or infusion site-related adverse events was rare.

The Topical Ocular Delivery of Rapamycin to Posterior Eye Tissues and the Suppression of Retinal Inflammatory Disease

Treatment of posterior eye diseases with intravitreal injections of drugs, while effective, is invasive and associated with side effects such as retinal detachment and endophthalmitis. In this work, we have formulated a model compound, rapamycin (RAP), in nanoparticle-based eye drops and evaluated the delivery of RAP to the posterior eye tissues in a healthy rabbit. We have also studied the formulation in experimental autoimmune uveitis (EAU) mouse model with retinal inflammation. Aqueous RAP eye drops were prepared using N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (Molecular Envelope Technology - MET) containing 0.23 ± 0.001% w/v RAP with viscosity, osmolarity, and pH within the ocular comfort range, and the formulation (MET-RAP) was stable in terms of drug content at both refrigeration and room temperature for one month. The MET-RAP eye drops delivered RAP to the choroid-retina with a Cmax of 145 ± 49 ng/g (tmax = 1 hour). The topical application of the MET-RAP eye drops to the EAU mouse model resulted in significant disease suppression compared to controls, with activity similar to dexamethasone eye drops. The MET-RAP eye drops also resulted in a reduction of RORγt and an increase in both Foxp3 expression and IL-10 secretion, indicating a mechanism involving the inhibition of Th17 cells and the up-regulation of T-reg cells. The MET-RAP formulation delivers RAP to the posterior eye segments, and the formulation is active in EAU.

Intravenous hypertonic saline to reduce intraocular pressure: the effect of splitting the bolus

PURPOSE

To compare intraocular pressure (IOP) and pain after a single versus split bolus of intravenous hypertonic saline (IVHTS).

METHODS

In a prospective, randomized, interventional trial, we enrolled patients with an IOP of 22-34 mmHg. Twenty patients in Group 1 received IVHTS as a single bolus of 1 mmol/kg 23.4% sodium chloride, and 13 patients in Group 2 received two boli of 0.5 mmol/kg separated by 10 min. They graded pain at the infusion site. We measured IOP, heart rate and blood pressure before and 10 and 20 min after IVHTS.

RESULTS

Eighteen patients (90%) in Group 1 felt pain (median, 6.5; range, 0-10). In Group 2, 11 patients (85%) felt pain after the first bolus (median, 6.0; range, 0-8) and 12 (92%) after the second one (median, 8; range, 0-10). We found no difference in pain grade between the groups after their first bolus (p = 0.33) or between the first bolus of Group 1 and the second bolus of Group 2 (p = 0.47). The median IOP reduction in Group 1 was 6.5 mmHg (range, 2-16) at 10 min and 7.0 mmHg (range, 4-16) at 20 min (p < 0.001 for both). In Group 2, the corresponding reductions after the second bolus were 9.0 mmHg (range, 4-10; p = 0.002) and 8.0 mmHg (range, 6-11; p = 0.002). The IOP reduction at 10 and 20 min was comparable between groups (p = 0.094 and p = 0.41, respectively).

CONCLUSION

Splitting the bolus did not reduce pain associated with IVHTS. Single bolus is consequently recommended.

A teaspoon of sugar and a pinch of salt: Reviewing hyperosmolar therapy

ABSTRACT

The traditional hyperosmolar agents used to treat patients with elevated intracranial pressure are mannitol and hypertonic sodium chloride solution. This article focuses on some of the pros and cons of these treatments for managing cerebral edema.

Evaluation of equiosmolar 20% mannitol, 3% hypertonic saline and 8.4% sodium bicarbonate on intraoperative brain relaxation and hemodynamic parameters in patients undergoing craniotomy for supratentorial tumors: a prospective randomized study

BACKGROUND

Research comparing 20% mannitol, 3% hypertonic saline and 8.4% sodium bicarbonate for intraoperative hyperosmolar therapy during supratentorial tumor excision is sparse. With the hypothesis that equiosmolar concentration of these agents will produce equivalent effects, this study was conducted to compare the effects on intraoperative brain relaxation and hemodynamics.

METHODS

The prospective study was conducted over a period of one year. Ninety patients, aged 18-60 years, American Society of Anesthesiologists class Ι and ΙΙ with supratentorial tumor and scheduled for surgery were randomized into three groups to receive equiosmolar 20% mannitol (group 1), 3% hypertonic saline (group 2) and 8.4% sodium bicarbonate (group 3). Primary outcome assessed was the effect on intraoperative brain relaxation score while hemodynamic parameters, changes in arterial blood gas parameters, serum electrolytes, serum osmolarity, urine output, fluid intake, post-operative course, hospital stay were the secondary outcomes.

RESULTS

Demographic characteristics, surgical and anesthetic variables, were comparable between the three groups. Brain relaxation scores were significantly better in group 3 compared to group 2 and group 1 respectively. Patients in group 1 had lower mean blood pressure and central venous pressure values, higher urine output, fluid intake compared to other groups. Patients of group 3 had significantly higher pH, bicarbonate, partial pressure of carbon dioxide, serum sodium and serum osmolarity values compared to groups 1 and 2.

CONCLUSIONS

Eight point four percent sodium bicarbonate solution infusion is associated with superior intraoperative brain relaxation scores and improved haemodynamic stability compared to equiosmolar 3% hypertonic saline solution and 20% mannitol.

Description of an Association Between Leukocytosis and Clinical Outcomes in Large Hemispheric Infarctions

BACKGROUND

Large hemispheric infarctions (LHI) are associated with significant morbidity and mortality. Leukocytosis has been observed to directly correlate with stroke severity but has not been specifically described in the LHI population. We hypothesized that patients with LHI and leukocytosis on admission have worse clinical outcomes.

METHODS

Retrospective study of patients admitted to the neurosciences intensive care unit at a tertiary care center with the diagnosis of acute ischemic stroke from Jan 2012 to Dec 2018. Inclusion criteria included admission imaging with stroke size greater than two-thirds of the middle cerebral artery territory, with or without other vascular territory involvement. Patients were excluded if antibiotics were started on admission for presumed infection. White blood cell count was recorded at admission, along with Modified Rankin Scale on admission and discharge, need for mechanical ventilation, tracheostomy, and discharge disposition. Logistic regression was used for association measures.

RESULTS

Of the 2,318 patients that were screened, 360 met inclusion criteria. Mean age was 64, median was 63; 51.7% were female. Mean and median NIHSS were 21. Leukocytosis on admission was seen in 139 patients (38.6%), and it was associated with need for mechanical ventilation (p<0.0001, OR 2.54, [1.64-3.95]) and mortality during hospitalization (p<0.0003, OR 2.66, [1.56-4.55]). Results persisted after correction for age and sex in a logistic regression model.

CONCLUSIONS

Leukocytosis on admission in patients with LHI significantly correlated with mortality and need for mechanical ventilation. There was a trend towards association with poor outcome at discharge, although not statistically significant. Further research may identify how leukocytosis and other SIRS markers may be used to prognosticate outcomes in this challenging patient population.

Terms, Definitions, Nomenclature, and Routes of Fluid Administration

Fluid therapy is administered to veterinary patients in order to improve hemodynamics, replace deficits, and maintain hydration. The gradual expansion of medical knowledge and research in this field has led to a proliferation of terms related to fluid products, fluid delivery and body fluid distribution. Consistency in the use of terminology enables precise and effective communication in clinical and research settings. This article provides an alphabetical glossary of important terms and common definitions in the human and veterinary literature. It also summarizes the common routes of fluid administration in small and large animal species.

Regional Lung Perfusion Analysis in Experimental ARDS by Electrical Impedance and Computed Tomography

Electrical impedance tomography is clinically used to trace ventilation related changes in electrical conductivity of lung tissue. Estimating regional pulmonary perfusion using electrical impedance tomography is still a matter of research. To support clinical decision making, reliable bedside information of pulmonary perfusion is needed. We introduce a method to robustly detect pulmonary perfusion based on indicator-enhanced electrical impedance tomography and validate it by dynamic multidetector computed tomography in two experimental models of acute respiratory distress syndrome. The acute injury was induced in a sublobar segment of the right lung by saline lavage or endotoxin instillation in eight anesthetized mechanically ventilated pigs. For electrical impedance tomography measurements, a conductive bolus (10% saline solution) was injected into the right ventricle during breath hold. Electrical impedance tomography perfusion images were reconstructed by linear and normalized Gauss-Newton reconstruction on a finite element mesh with subsequent element-wise signal and feature analysis. An iodinated contrast agent was used to compute pulmonary blood flow via dynamic multidetector computed tomography. Spatial perfusion was estimated based on first-pass indicator dilution for both electrical impedance and multidetector computed tomography and compared by Pearson correlation and Bland-Altman analysis. Strong correlation was found in dorsoventral (r = 0.92) and in right-to-left directions (r = 0.85) with good limits of agreement of 8.74% in eight lung segments. With a robust electrical impedance tomography perfusion estimation method, we found strong agreement between multidetector computed and electrical impedance tomography perfusion in healthy and regionally injured lungs and demonstrated feasibility of electrical impedance tomography perfusion imaging.

Postoperative resuscitation with hypertonic saline or hyperoncotic albumin in patients following cardiac surgery: A review of the literature

BACKGROUND

Over-resuscitation in postcardiac surgery patients is associated with significant morbidity and mortality. Accordingly, there is a growing interest in hyperoncotic albumin and hypertonic saline for resuscitation in patients following cardiac surgery. In this article, we will review the use of hyperosmolar fluid therapies for resuscitation in postcardiac surgical patients from the current literature.

METHODS

A literature search was conducted in MEDLINE (PubMed) utilizing keywords, narrowing publications from 2009 to 2020.

RESULTS

Patients receiving concentrated albumin after cardiac surgery required less fluid bolus therapy, less time on vasopressors, and had a lower positive fluid balance compared with patients receiving crystalloids. There was no difference in mortality in those given 20% albumin compared with crystalloids postcardiac surgery. Patients administered hypertonic saline following cardiac surgery had increased urinary output but its effect on total fluid and body weight was not significantly different compared with crystalloids.

CONCLUSIONS

In this analysis, publications on resuscitation with hyperoncotic albumin and hypertonic saline in patients following cardiac surgery were reviewed. While there is data supporting the use of alternative fluid therapies in other critically ill populations, the limited literature focused on concentrated albumin and hypertonic saline for resuscitation following cardiac surgery is equivocal.

Immunomodulatory Effect of Hypertonic Saline Solution in Traumatic Brain-Injured Patients and Intracranial Hypertension

Traumatic brain injury (TBI) is often associated with an increase in the intracranial pressure (ICP). This increase in ICP can cross the physiological range and lead to a reduction in cerebral perfusion pressure (CPP) and the resultant cerebral blood flow (CBF). It is this reduction in the CBF that leads to the secondary damage to the neural parenchyma along with the physical axonal and neuronal damage caused by the mass effect. In certain cases, a surgical intervention may be required to either remove the mass lesion (hematoma of contusion evacuation) or provide more space to the insulted brain to expand (decompressive craniectomy). Whether or not a surgical intervention is performed, all these patients require some form of pharmaceutical antiedema agents to bring down the raised ICP. These agents have been broadly classified as colloids (e.g., mannitol, glycerol, urea) and crystalloids (e.g., hypertonic saline), and have been used since decades. Even though mannitol has been the workhorse for ICP reduction owing to its unique properties, crystalloids have been found to be the preferred agents, especially when long-term use is warranted. The safest and most widely used agent is hypertonic saline in various concentrations. Whatever be the concentration, hypertonic saline has created special interest among physicians owing to its additional property of immunomodulation and neuroprotection. In this review, we summarize and understand the various mechanism by which hypertonic saline exerts its immunomodulatory effects that helps in neuroprotection after TBI.

Evaluation of the Distribution and Elimination of Balanced Isotonic Crystalloid, 5% Hypertonic Saline, and 6% Tetrastarch 130/0.4 Using Volume Kinetic Modeling and Analysis in Healthy Conscious Cats

This prospective, randomized, blinded, interventional cross-over study investigated the distribution, elimination, plasma volume expansion, half-life, comparative potency, and ideal fluid prescription of three commonly prescribed intravenous (IV) fluids in 10 healthy conscious cats using volume kinetic analysis that is novel to veterinary medicine. Each cat received 20 mL/kg of balanced isotonic crystalloid (PLA), 3.3 mL/kg of 5% hypertonic saline (HS), and 5 mL/kg of 6% tetrastarch 130/0.4 (HES) over 15 min on separate occasions. Hemoglobin concentration, red blood cell count, hematocrit, heart rate, and blood pressure were measured at baseline, 5, 10, 15, 20, 30, 40, 50, 60, and every 15 min until 180 min. Urine output was estimated every 30 min using point-of-care bladder ultrasonography. Plasma dilution derived from serial hemoglobin concentration and red blood cell count served as input variables for group and individual fluid volume kinetic analyses using a non-linear mixed effects model. In general, the distribution of all IV fluids was rapid, while elimination was slow. The half-lives of PLA, HS, and HES were 49, 319, and 104 min, respectively. The prescribed fluid doses for PLA, HS, and HES resulted in similar peak plasma volume expansion of 27–30%. The potency of HS was 6 times higher than PLA and 1.7 times greater than HES, while HES was 3.5 times more potent than PLA. Simulation of ideal fluid prescriptions to achieve and maintain 15 or 30% plasma volume expansion revealed the importance of a substantial reduction in infusion rates following initial IV fluid bolus. In conclusion, volume kinetic analysis is a feasible research tool that can provide data on IV fluid kinetics and body water physiology in cats. The rapid distribution but slow elimination of IV fluids in healthy conscious cats is consistent with anecdotal reports of fluid overload susceptibility in cats and warrants further investigation.

Prehospital clinical signs are a poor predictor of raised intracranial pressure following traumatic brain injury

Background

For the prehospital diagnosis of raised intracranial pressure (ICP), clinicians are reliant on clinical signs such as the Glasgow Coma Score (GCS), pupillary response and/or Cushing’s triad (hypertension, bradycardia and an irregular breathing pattern). This study aimed to explore the diagnostic accuracy of these signs as indicators of a raised ICP.

Methods

We performed a retrospective cohort study of adult patients attended by a Helicopter Emergency Medical Service (Air Ambulance Kent, Surrey Sussex), who had sustained a traumatic brain injury (TBI), requiring prehospital anaesthesia between 1 January 2016 and 1 January 2018. We established optimal cut-off values for clinical signs to identify patients with a raised ICP and investigated diagnostic accuracy for combinations of these values.

Results

Outcome data for 249 patients with TBI were available, of which 87 (35%) had a raised ICP. Optimal cut-off points for systolic blood pressure (SBP), heart rate (HR) and pupil diameter to discriminate patients with a raised ICP were, respectively, >160 mm Hg,<60 bpm and >5 mm. Cushing criteria (SBP >160 mm Hg and HR <60 bpm) and pupillary response and size were complimentary in their ability to detect patients with a raised ICP. The presence of a fixed blown pupil or a Cushing’s response had a specificity of 93.2 (88.2–96.6)%, and a positive likelihood ratio (LR+) of 5.4 (2.9–10.2), whereas sensitivity and LR− were only 36.8 (26.7–47.8)% and 0.7 (0.6–0.8), respectively, (Area Under the Curve (AUC) 0.65 (0.57–0.73)). Sensitivity analysis revealed that optimal cut-off values and resultant accuracy were dependent on injury pattern.

Conclusion

Traditional clinical signs of raised ICP may under triage patients to prehospital treatment with hyperosmolar drugs. Further research should identify more accurate clinical signs or alternative non-invasive diagnostic aids in the prehospital environment.

Hypertonic Saline Solution Reduces Microcirculatory Dysfunction and Inflammation in a Rat Model of Brain Death

BACKGROUND

Brain death (BD) induces hemodynamic instability with microcirculatory hypoperfusion, leading to increased organ inflammation and dysfunction. This study investigated the effects of 7.5% hypertonic saline solution (HSS) on mesenteric microcirculatory dysfunction and inflammation in a rat model of BD.

METHODS

Male Wistar rats were anesthetized and mechanically ventilated. BD was induced by rapidly inflating an intracranial balloon catheter. The rats were randomly divided into: SH, sham-operated rats subjected to trepanation; NS, rats treated with NaCl 0.9%, 4 mL/kg immediately after BD; T1, rats treated with HSS (NaCl 7.5%, 4 mL/kg) immediately or 60 min after BD, T60. All groups were analyzed 180 min after the start of the experiment.

RESULTS

Rats in BD groups presented with a similar hypertensive peak, followed by hypotension. Proportion of perfused small vessels was decreased in the NS group (46%) compared with the SH group (74%, P = 0.0039). HSS restored the proportion of perfused vessels (T1 = 71%, P = 0.0018). The anti-endothelial nitric oxide synthase (eNOS) protein expression significantly increased in rats given HSS (T1, and T60, P = 0.0002). Similar results were observed regarding endothelin-1 (P < 0.0001). Increased numbers of rolling (P = 0.0015) and migrated (P = 0.0063) leukocytes were observed in the NS group compared with the SH group. Rats given HSS demonstrated an overall reduction in leukocyte-endothelial interactions. The ICAM-1 levels increased in the NS group compared with the SH group, and decreased in the HSS-treated groups (P = 0.0002).

CONCLUSIONS

HSS may improve the density of mesenteric perfused small vessels due to its effects on eNOS and endothelin-1 protein expression, and reduces inflammation by decreasing leukocyte adhesion and migration in a rat model of BD.

Divergent Effects of Hypertonic Fluid Resuscitation on Renal Pathophysiological and Structural Parameters in Rat Model of Lower Body Ischemia/Reperfusion-Induced Sterile Inflammation

The pathogenesis of acute kidney injury (AKI) is characterized by the deterioration of tissue perfusion and oxygenation and enhanced inflammation. The purpose of this study was to investigate whether or not the hemodynamic and inflammatory effects of hypertonic saline (HS) protect the kidney by promoting renal microcirculatory oxygenation and possible deleterious effects of HS due to its high sodium content on renal functional and structural injury following ischemia/reperfusion. Mechanically ventilated and anesthetized rats were randomly divided into four groups (n = 6 per group): a sham-operated control group; a group subjected to renal ischemia for 45 min by supra-aortic occlusion followed by 2 h of reperfusion (I/R); and I/R group treated with a continuous i.v. infusion (5 mL/kg/h) of either % 0.9 NaCl (IR+NS) or %10 NaCl (I/R+HS) after releasing the clamp. Systemic and renal hemodynamic, renal cortical (CμPO2), and medullar microcirculatory pO2 (MμPO2) are measured by the oxygen-dependent quenching of the phosphorescence lifetime technique. Renal functional, inflammatory, and tissues damage parameters were also assessed. HS, but not NS, treatment restored I/R-induced reduced mean arterial pressure, CμPO2, renal oxygen deliver (DO2ren), and consumption (VO2ren). HS caused a decrease in tubular sodium reabsorption (TNa) that correlated with an elevation of fractional sodium excretion (EFNa) and urine output. HS had an anti-inflammatory effect by reducing the levels TNF-α, IL-6, and hyaluronic acid in the renal tissue samples as compared with the I/R and I/R+NS groups (P < 0.05). HS treatment was also associated with mild acidosis and an increased renal tubular damage. Despite HS resuscitation improving the systemic hemodynamics, microcirculatory oxygenation, and renal oxygen consumption as well as inflammation, it should be limited or strictly controlled for long-term use because of provoking widespread renal structural damage.

Damage Control Resuscitation

Damage control resuscitation (DCR) is a strategy for resuscitating patients from hemorrhagic shock to rapidly restore homeostasis. Efforts are focused on blood product transfusion with whole blood or component therapy closely approximating whole blood, limited use of crystalloid to avoid dilutional coagulopathy, hypotensive resuscitation until bleeding control is achieved, empiric use of tranexamic acid, prevention of acidosis and hypothermia, and rapid definitive surgical control of bleeding. Patients receiving uncrossmatched Type O blood in the emergency department and later receiving cumulative transfusions of 10 or more red blood cell units in the initial 24-hour post-injury (massive transfusion) are widely recognized as being at increased risk of morbidity and mortality due to exsanguination. Ideally, these patients should be rapidly identified, however anticipating transfusion needs is challenging. Useful indicators of massive transfusion reviewed in this guideline include: systolic blood pressure <110 mmHg, heart rate > 105 bpm, hematocrit <32%, pH < 7.25, injury pattern (above-the-knee traumatic amputation especially if pelvic injury is present, multi-amputation, clinically obvious penetrating injury to chest or abdomen), >2 regions positive on Focused Assessment with Sonography for Trauma (FAST) scan, lactate concentration on admission >2.5, admission international normalized ratio ≥1.2-1.4, near infrared spectroscopy-derived StO2 < 75% (in practice, rarely available), BD > 6 meq/L. Unique aspects of out-of-hospital DCR (point of injury, en-route, and remote DCR) and in-hospital (Medical Treatment Facilities: Role 2b/Forward surgical teams - role 3/ combat support hospitals) are reviewed in this guideline, along with pediatric considerations.

A Retrospective Study of Intracranial Pressure in Head-Injured Patients Undergoing Decompressive Craniectomy: A Comparison of Hypertonic Saline and Mannitol

Objective: The impact of hypertonic saline (HTS) on the control of increased intracranial pressure (ICP) in head-injured patients undergoing decompressive craniectomy (DC) has yet to be established. The current retrospective study was conducted to compare the effect of HTS and mannitol on lowering the ICP burden of these patients.

Methods: We reviewed data on patients who had sustained a traumatic brain injury (TBI) and were admitted to the First People's Hospital of Kunshan between January 1, 2012, and August 31, 2017. Patients who received only one type of hyperosmotic agent, 3% HTS or 20% mannitol, after DC were included. The daily ICP burden (h/day) and response to the hyperosmolar agent were used as primary outcome measures. The numbers of days in the intensive care unit and in the hospital, and the 2-weeks mortality rates were also compared between the groups.

Results: The 30 patients who received 3% HTS only and the 30 who received 20% mannitol only were identified for approximate matching and additional data analyses. The demographic characteristics of the patients in the two groups were comparable, but the daily ICP burden was significantly lower in the HTS group than in the mannitol group (0.89 ± 1.02 h/day vs. 2.11 ± 2.95 h/day, respectively; P = 0.038). The slope of the reduction in ICP in response to a bolus dose at baseline was higher with HTS than with mannitol (P = 0.001). However, the between-group difference in the 2-weeks mortality rates was not statistically significant (2 [HTS] vs. 1 [mannitol]; P = 0.554).

Conclusion: When used in equiosmolar doses, the reduction in the ICP of TBI patients achieved with 3% HTS was superior to that achieved with 20% mannitol after DC. However, this advantage did not seem to confer any additional benefit terms of short-term mortality.

Management of raised intracranial pressure in aneurysmal subarachnoid hemorrhage: time for a consensus?

Elevated intracranial pressure (ICP) is a well-recognized phenomenon in aneurysmal subarachnoid hemorrhage (aSAH) that has been demonstrated to lead to poor outcomes. Despite significant advances in clinical research into aSAH, there are no consensus guidelines devoted specifically to the management of elevated ICP in the setting of aSAH. To treat high ICP in aSAH, most centers extrapolate their treatment algorithms from studies and published guidelines for traumatic brain injury. Herein, the authors review the current management strategies for treating raised ICP within the aSAH population, emphasize key differences from the traumatic brain injury population, and highlight potential directions for future research in this controversial topic.

Intravenous Hypertonic Saline to Lower Intraocular Pressure in Ocular Hypertension and Primary Open-angle and Exfoliation Glaucoma

PURPOSE

The purpose of this article was to quantitate the effect of intravenous hypertonic saline (IVHTS) on elevated intraocular pressure (IOP) among 3 groups of glaucoma patients or suspects.

MATERIALS AND METHODS

Among the forty-four patients with IOP 24 to 30 mm Hg included in this study, 13 had ocular hypertension (OHT), 14 primary open-angle glaucoma (POAG), and 17 exfoliation glaucoma (ExG). Participants received a bolus of 23.4% IVHTS (1.0 mmol/kg) through an antecubital vein. We measured IOP, heart rate, and blood pressure before the bolus, thereafter every minute for 10 minutes, and less frequently for 2 hours.

RESULTS

The median baseline IOP was 24 mm Hg (range, 24 to 30 mm Hg), 26.5 mm Hg (range, 24 to 30 mm Hg), and 26 mm Hg (range, 24 to 30 mm Hg) in OHT, POAG, and ExG patients, respectively. Sixteen minutes after the bolus, IOP was a median of 9 mm Hg (range, 4 to 12 mm Hg), 10 mm Hg (range, 6 to 12 mm Hg), and 10 mm Hg (range, 4 to 14 mm Hg) lower in OHT, POAG, and ExG groups (P=0.70), respectively. After 1 hour, the median IOP reduction was similar between ExG (9 mm Hg; range, 4 to 14 mm Hg) and POAG patients (9.5 mm Hg; range, 6 to 12 mm Hg) but lower in OHT patients (6 mm Hg; range, 2 to 9 mm Hg; P=0.006). Heart rate decreased by a median of 7 beats/min. Blood pressure increased within 3 minutes (median, mm Hg; 15 systolic; 5 diastolic), but returned to baseline at 10 minutes. Within 1 to 3 minutes of treatment, 36 (82%) patients felt pain in the infusion arm, and 29 (66%) reported a feeling of warmth in their head.

CONCLUSIONS

IVHTS reduced IOP effectively in all groups.

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

AIM

Osmotherapy 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.

METHOD

A 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.

RESULTS

Eight 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.

CONCLUSIONS

Mannitol 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.

Analyzing the efficacy of frequent sodium checks during hypertonic saline infusion after elective brain tumor surgery

OBJECTIVE

To assess the utility of frequent sodium checks (every 6h) in patients receiving hypertonic saline (HS) after elective brain tumor surgeries.

PATIENTS AND METHODS

A single-institution retrospective review of patients having undergone elective craniotomies for brain tumors and treated with postoperative continuous intravenous infusions of 3% HS was performed. Changes in serum sodium values were analyzed at different time points. The rates of <12.5, 25, and 50cc/h infusions were also examined. Healthcare cost analysis was performed by extrapolating our cohort to the total number of craniotomies performed in the United States.

RESULTS

No significant differences among sodium values checked between 0 to 4, 4-6, 6-8, 8-10, and >10h were observed (P=.64). In addition, no differences in serum sodium values among the rates of <12.5, 25, and 50cc/h were found (P=.30). No patients developed symptoms of acute hypernatremia.

CONCLUSIONS

Serum sodium values did not significantly change more than 10h after infusion of HS. Further studies are needed to determine the optimal frequency of routine sodium checks to increase the quality of care and decrease healthcare costs.

Definition, evaluation, and management of brain relaxation during craniotomy

The term 'brain relaxation' is routinely used to describe the size and firmness of the brain tissue during craniotomy. The status of brain relaxation is an important aspect of neuroanaesthesia practice and is relevant to the operating conditions, retraction injury, and likely patient outcomes. Brain relaxation is determined by the relationship between the volume of the intracranial contents and the capacity of the intracranial space (i.e. a content-space relationship). It is a concept related to, but distinct from, intracranial pressure. The evaluation of brain relaxation should be standardized to facilitate clinical communication and research collaboration. Both advantageous and disadvantageous effects of the various interventions for brain relaxation should be taken into account in patient care. The outcomes that matter the most to patients should be emphasized in defining, evaluating, and managing brain relaxation. To date, brain relaxation has not been reviewed specifically, and the aim of this manuscript is to discuss the current approaches to the definition, evaluation, and management of brain relaxation, knowledge gaps, and targets for future research.

Comparison of 3% and 7.5% Hypertonic Saline in Resuscitation After Traumatic Hypovolemic Shock

Hypertonic saline solutions (HSSs) (7.5%) are useful in the resuscitation of patients with hypovolemic shock because they provide immediate intravascular volume expansion via the delivery of a small volume of fluid, improving cardiac function. However, the effects of using 3% HSS in hypovolemic shock resuscitation are not well known. This study was designed to compare the effects of and complications associated with 3% HSS, 7.5% HSS, and standard fluid in resuscitation. In total, 294 severe trauma patients were enrolled from December 2008 to February 2012 and subjected to a double-blind randomized clinical trial. Individual patients were treated with 3% HSS (250 mL), 7.5% HSS (250 mL), or lactated Ringer's solution (LRS) (250 mL). Mean arterial pressure, blood pressure, and heart rate were monitored and recorded before fluid infusion and at 10, 30, 45, and 60 min after infusion, and the incidence of complications and survival rate were analyzed. The results indicate that 3% and 7.5% HSSs rapidly restored mean arterial pressure and led to the requirement of an approximately 50% lower total fluid volume compared with the LRS group (P < 0.001). However, a single bolus of 7.5% HSS resulted in an increase in heart rate (mean of 127 beats/min) at 10 min after the start of resuscitation. Higher rates of arrhythmia and hypernatremia were noted in the 7.5% HSS group, whereas higher risks of renal failure (P< 0.001), coagulopathy (P < 0.001), and pulmonary edema (P < 0.001) were observed in the LRS group. Neither severe electrolyte disturbance nor anaphylaxis was observed in the HSS groups. It is notable that 3% HSS had similar effects on resuscitation because both the 7.5% HSS and LRS groups but resulted in a lower occurrence of complications. This study demonstrates the efficacy and safety of 3% HSS in the resuscitation of patients with hypovolemic shock.

Water-Borne Endovascular Embolics Inspired by the Undersea Adhesive of Marine Sandcastle Worms

Transcatheter embolization is used to treat vascular malformations and defects, to control bleeding, and to selectively block blood supply to tissues. Liquid embolics are used for small vessel embolization that require distal penetration. Current liquid embolic agents have serious drawbacks, mostly centered around poor handling characteristics and toxicity. In this work, a water-borne in situ setting liquid embolic agent is described that is based on electrostatically condensed, oppositely charged polyelectrolytes-complex coacervates. At high ionic strengths, the embolic coacervates are injectable fluids that can be delivered through long narrow microcatheters. At physiological ionic strength, the embolic coacervates transition into a nonflowing solid morphology. Transcatheter embolization of rabbit renal arteries demonstrated capillary level penetration, homogeneous occlusion, and 100% devascularization of the kidney, without the embolic crossing into venous circulation. The benign water-borne composition and setting mechanism avoids many of the problems of current liquid embolics, and provides precise temporal and spatial control during endovascular embolization.

Equine anaesthesia-associated mortality: where are we now?

OBJECTIVES

To review the literature concerning mortality associated with general anaesthesia in horses and to assess whether there is evidence for a reduction in mortality over the 20 years since the Confidential Enquiry into Perioperative Equine Fatalities (CEPEF).

DATABASES USED

PubMed, Scopus, Google Scholar. Search terms used: horse; pony; equine; anaesthesia; anesthesia; recovery; morbidity, and mortality.

CONCLUSIONS

The most recent studies, in which isoflurane and sevoflurane have been more commonly used for anaesthesia maintenance, report fewer intraoperative cardiac arrests than older studies in which halothane was favoured. Catastrophic fractures, however, have become the greatest cause of recovery-associated mortality.

Hypernatremia is a significant risk factor for acute kidney injury after subarachnoid hemorrhage: a retrospective analysis

BACKGROUND

Hypertonic saline therapy is often used in critically ill subarachnoid hemorrhage (SAH) patients for indications ranging from control of intracranial hypertension to managing symptomatic hyponatremia. The risk factors for developing acute kidney injury (AKI) in this patient population are not well defined.

SPECIFIC AIM

To study the role of serum sodium in developing AKI (based on the AKIN definition) in the SAH population admitted to a large academic neurocritical care unit.

METHODS

This is an IRB-approved, retrospective cohort study of patients admitted to a tertiary neuro intensive care unit. We included adult (age ≥ 18 years) SAH patients admitted to the neuro intensive care unit for at least 72 h. Development of AKI after admission to the ICU was defined using the AKIN serum creatinine criteria between 72 h and 14 days following admission. A Cox proportional hazards survival model with multiple time varying covariates was developed to evaluate the effect of maximum sodium exposure on the risk of AKI. Sodium exposure was captured as the running maximum of daily maximum serum sodium concentration (mEq/L). Sodium exposure was used as a surrogate for hypertonic saline therapy.

RESULTS

The final cohort of patients included 736 patients admitted to the neuro intensive care unit between 2006 and 2012. The number of patients who developed AKI was 64 (9 %). These patients had an increased length of stay (15.6 ± 9.4 vs. 12.5 ± 8.7 days). The odds of death were more than two fold greater among patients who developed AKI (odds ratio 2.33 95 % CI 1.27, 4.3). Sodium exposure was significantly associated with the hazard of developing AKI, adjusting for age, sex, preexisting renal disease, diabetes mellitus, radiocontrast exposure, number of days on mechanical ventilation, and admission Glasgow Coma Scale score. For each 1 mEq/L increase in the running maximum daily serum sodium, the hazard of developing AKI was increased by 5.4 % (95 % CI 1.4, 9.7).

CONCLUSION

The maximum daily sodium is a significant risk factor for developing AKI in patients with SAH.

Effects of different types of fluid resuscitation for hemorrhagic shock on splanchnic organ microcirculation and renal reactive oxygen species formation

INTRODUCTION

Fluid resuscitation is an indispensable procedure in the acute management of hemorrhagic shock for restoring tissue perfusion, particularly microcirculation in splanchnic organs. Resuscitation fluids include crystalloids, hypertonic saline (HTS), and synthetic colloids, and their selection affects the recovery of microcirculatory blood flow and reactive oxygen species (ROS) formation, which is often evident in the kidney, following reperfusion. In this study, the effects of acute resuscitation with 0.9% saline (NS), 3% HTS, 4% succinylated gelatin (GEL), and 6% hydroxyethyl starch (HES) 130/0.4 were compared in a hemorrhagic shock rat model to analyze restoration of microcirculation among various splanchnic organs and the gracilis muscle and reperfusion-induced renal ROS formation.

METHODS

A total of 96 male Wistar rats were subjected to sham operation (sham group), hemorrhagic shock (control group), and resuscitation with NS, HTS, GEL and HES. Two hours after resuscitation, changes in the mean arterial pressure (MAP), serum lactate level and the microcirculatory blood flow among various splanchnic organs, namely the liver, kidney, and intestine (mucosa, serosal muscular layer, and Peyer's patch), and the gracilis muscle, were compared using laser speckle contrast imaging. Renal ROS formation after reperfusion was investigated using an enhanced in vivo chemiluminescence (CL) method.

RESULTS

Microcirculatory blood flow was less severely affected by hemorrhaging in the liver and gracilis muscle. Impairment of microcirculation in the kidney was restored in all resuscitation groups. Resuscitation in the NS group failed to restore intestinal microcirculation. Resuscitation in the HTS, GEL, and HES groups restored intestinal microcirculatory blood flow. By comparison, fluid resuscitation restored hemorrhagic shock-induced hypotension and decreased lactatemia in all resuscitation groups. Reperfusion-induced in vivo renal ROS formation was significantly higher in the GEL and HES groups than in the other groups.

CONCLUSION

Although fluid resuscitation with NS restored the MAP and decreased lactatemia following hemorrhagic shock, intestinal microcirculation was restored only by other volume expanders, namely 3% HTS, GEL, and HES. However, reperfusion-induced renal ROS formation was significantly higher when synthetic colloids were used.

Immunomodulatory effect of hypertonic saline in hemorrhagic shock

Multiple organ dysfunction syndrome (MODS) and nosocomial infection following trauma-hemorrhage are among the most important causes of mortality in hemorrhagic shock patients. Dysregulation of the immune system plays a central role in MODS and a fluid having an immunomodulatory effect could be advantageous in hemorrhagic shock resuscitation. Hypertonic saline (HS) is widely used as a resuscitation fluid in trauma-hemorrhagic patients. Besides having beneficial effects on the hemodynamic parameters, HS has modulatory effects on various functions of immune cells such as degranulation, adhesion molecules and cytokines expression, as well as reactive oxygen species production. This article reviews clinical evidence for decreased organ failure and mortality in hemorrhagic shock patients resuscitated with HS. Despite promising results in animal models, results from pre-hospital and emergency department administration in human studies did not show improvement in survival, organ failure, or a reduction in nosocomial infection by HS resuscitation. Further post hoc analysis showed some benefit from HS resuscitation for severely-injured patients, those who received more than ten units of blood by transfusion, patients who underwent surgery, and victims of traumatic brain injury. Several reasons are suggested to explain the differences between clinical and animal models.

Efficacy and Safety of Continuous Micro-Pump Infusion of 3% Hypertonic Saline combined with Furosemide to Control Elevated Intracranial Pressure

Background

Elevated intracranial pressure is one of the most common problems in patients with diverse intracranial disorders, leading to increased morbidity and mortality. Effective management for increased intracranial pressure is based mainly on surgical and medical techniques with hyperosmolar therapy as one of the core medical treatments. The study aimed to explore the effects of continuous micro-pump infusions of 3% hypertonic saline combined with furosemide on intracranial pressure control.

Material/Methods

We analyzed data on 56 eligible participants with intracranial pressure >20 mmHg from March 2013 to July 2014. The target was to increase and maintain plasma sodium to a level between 145 and 155 mmol/L and osmolarity to a level of 310 to 320 mOsmol/kg.

Results

Plasma sodium levels significantly increased from 138±5 mmol/L at admission to 151±3 mmol/L at 24 h (P<0.01). Osmolarity increased from 282±11 mOsmol/kg at baseline to 311±8 mOsmol/kg at 24 h (P<0.01). Intracranial pressure significantly decreased from 32±7 mmHg to 15±6 mmHg at 24 h (P<0.01). There was a significant improvement in CPP (P<0.01). Moreover, central venous pressure, mean arterial pressure, and Glasgow Coma Scale slightly increased. However, these changes were not statistically significant.

Conclusions

Continuous infusion of 3% hypertonic saline + furosemide is effective and safe for intracranial pressure control.

Understanding the pathophysiology of traumatic brain injury and the mechanisms of action of neuroprotective interventions

Traumatic brain injury continues to be a major socioeconomic problem, costing the United States $76.5 billion in the year of 2000. Despite the advances in the field of medicine, there are still no definitive treatments for traumatic brain injury. Goal of therapy is still gearing toward supportive cares such as intracranial pressure monitoring, lowering intracranial pressure, correcting cerebral ischemia, and manipulating serum osmolarity. The search for effective treatment in human studies has been unfruitful. In this review, the mechanisms of primary and secondary brain injury are discussed along with potential neuroprotective interventions such as hyperosmolar therapies, hypothermia, statins, and cyclosporin A.