ROC trials update on prehospital hypertonic saline resuscitation in the aftermath of the US-Canadian trials

ALM Resuscitation With Brain and Multiorgan Protection for Far-Forward Operations: Survival at Hypotensive Pressures

INTRODUCTION

Non-compressible torso hemorrhagic (NCTH) shock is the leading cause of potentially survivable trauma on the battlefield. New hypotensive drug therapies are urgently required to resuscitate and protect the heart and brain following NCTH. Our aim was to examine the strengths and limitations of permissive hypotension and discuss the development of small-volume adenosine, lidocaine, and Mg2+ (ALM) fluid resuscitation in rats and pigs.

MATERIALS AND METHODS

For review of permissive hypotension, a literature search was performed from inception up to November 2023 using PubMed, Cochrane, and Embase databases, with inclusion of animal studies, clinical trials and reviews with military and clinical relevance. For the preclinical study, adult female pigs underwent laparoscopic liver resection. After 30 minutes of bleeding, animals were resuscitated with 4 mL/kg 3% NaCl ± ALM bolus followed 60 minutes later with 4 h 3 mL/kg/h 0.9% NaCl ± ALM drip (n = 10 per group), then blood transfusion. Mean arterial pressure (MAP) and cardiac output (CO) were continuously measured via a left ventricular pressure catheter and pulmonary artery catheter, respectively. Systemic vascular resistance (SVR) was calculated using the formula: 80 × (MAP - CVP)/CI. Oxygen delivery was calculated as the product of CO and arterial oxygen content.

RESULTS

Targeting a MAP of ∼50 mmHg can be harmful or beneficial, depending on how CO and SVR are regulated. A theoretical example shows that for the same MAP of 50 mmHg, a higher CO and lower SVR can lead to a nearly 2-fold increase in O2 supply. We further show that in animal models of NCTH, 3% NaCl ALM bolus and 0.9% NaCl ALM drip induce a hypotensive, high flow, vasodilatory state with maintained tissue O2 supply and neuroprotection. ALM therapy increases survival by resuscitating the heart, reducing internal bleeding by correcting coagulopathy, and decreasing secondary injury.

CONCLUSIONS

In rat and pig models of NCTH, small-volume ALM therapy resuscitates at hypotensive pressures by increasing CO and reducing SVR. This strategy is associated with heart and brain protection and maintained tissue O2 delivery. Translational studies are required to determine reproducibility and optimal component dosing. ALM therapy may find wide utility in prehospital and far-forward military environments.

Hypertonic saline infusion does not improve the chance of primary fascial closure after damage control laparotomy: a randomized controlled trial

BACKGROUND

Previous observational studies showed higher rates of abdominal wall closure with the use of hypertonic saline in trauma patients with abdominal injuries. However, no randomized controlled trials have been performed on this matter. This double-blind randomized clinical trial assessed the effect of 3% hypertonic saline (HS) solution on primary fascial closure and the timing of abdominal wall closure among patients who underwent damage control laparotomy for bleeding control.

METHODS

Double-blind randomized clinical trial. Patients with abdominal injuries requiring damage control laparotomy (DCL) were randomly allocated to receive a 72-h infusion (rate: 50 mL/h) of 3% HS or 0.9 N isotonic saline (NS) after the index DCL. The primary endpoint was the proportion of patients with abdominal wall closure in the first seven days after the index DCL.

RESULTS

The study was suspended in the first interim analysis because of futility. A total of 52 patients were included. Of these, 27 and 25 were randomly allocated to NS and HS, respectively. There were no significant differences in the rates of abdominal wall closure between groups (HS: 19 [79.2%] vs. NS: 17 [70.8%]; p = 0.71). In contrast, significantly higher hypernatremia rates were observed in the HS group (HS: 11 [44%] vs. NS: 1 [3.7%]; p < 0.001).

CONCLUSION

This double-blind randomized clinical trial showed no benefit of HS solution in primary fascial closure rates. Patients randomized to HS had higher sodium concentrations after the first day and were more likely to present hypernatremia. We do not recommend using HS in patients undergoing damage control laparotomy. Trial registration The trial protocol was registered in clinicaltrials.gov (identifier: NCT02542241).

Hypertonic Saline in Human Sepsis: A Systematic Review of Randomized Controlled Trials

The role of hypertonic saline in sepsis remains unclear because clinical data are limited and the balance between beneficial and adverse effects is not well defined. In this systematic literature review, we searched PubMed and Embase to identify all randomized controlled trials up until January 31, 2018 in which hypertonic saline solutions of any concentration were used in patients of all ages with sepsis and compared to a cohort of patients receiving an isotonic fluid. We identified 8 randomized controlled trials with 381 patients who had received hypertonic saline. Lower volumes of hypertonic saline than of isotonic solutions were needed to achieve the desired hemodynamic goals (standardized mean difference, -0.702; 95% CI, -1.066 to -0.337; P < .001; moderate-quality evidence). Hypertonic saline administration was associated with a transient increase in sodium and chloride concentrations without adverse effects on renal function (moderate-quality evidence). Some data suggested a beneficial effect of hypertonic saline solutions on some hemodynamic parameters and the immunomodulatory profile (very low-quality evidence). Mortality rates were not significantly different with hypertonic saline than with other fluids (odds ratio, 0.946; 95% CI, 0.688-1.301; P = .733; low-quality evidence). In conclusion, in our meta-analysis of studies in patients with sepsis, hypertonic saline reduced the volume of fluid needed to achieve the same hemodynamic targets but did not affect survival.

Variable saline resuscitation in a murine model of combined traumatic brain injury and haemorrhage

BACKGROUND

Resuscitation strategies for combined traumatic brain injury (TBI) with haemorrhage in austere environments are not fully established. Our aim was to establish the effects of various saline concentrations in a murine model of combined TBI and haemorrhage, and identify an effective resuscitative strategy for the far-forward environment.

METHODS

Male C57BL/6 mice underwent closed head injury and subjected to controlled haemorrhage to a systolic blood pressure of 25 mmHg via femoral artery cannulation for 60 min. Mice were resuscitated with a fixed volume bolus or variable volumes of fluid to achieve a systolic blood pressure goal of 80 mmHg with 0.9% saline, 3% saline, 0.1-mL bolus of 23.4% saline, or a 0.1-mL bolus of 23.4% saline followed by 0.9% saline (23.4+).

RESULTS

23.4% saline and 23.4+ resulted in higher mortality at 6 h compared to 0.9% saline. Use of 3% saline required less volume to achieve targeted resuscitation, did not affect survival, and did not exacerbate post-traumatic inflammation. While 23.4+ resuscitation utilized lower volume, it resulted in hypernatremia, azotemia, and elevated systemic pro-inflammatory cytokines. All groups except 3% saline demonstrated progression of neuron damage, with cerebral oedema highest with 0.9% saline.

CONCLUSIONS

3% saline demonstrated favourable balance of survival, blood pressure restoration, minimization of inflammation, and prevention of ongoing neurologic injury without contributing to significant physiologic derangements. 23.4% saline administration may not be appropriate in the setting of concomitant hypotension.

7.5% NaCl Resuscitation Leads to Abnormal Clot Fibrinolysis after Severe Hemorrhagic Shock and its Correction with 7.5% NaCl Adenosine, Lidocaine, and Mg2

Background

Hyperfibrinolysis is a common complication of hemorrhagic shock. Our aim was to examine the effect of small-volume 7.5% NaCl adenosine, lidocaine, and Mg²⁺ (ALM) on fibrinolysis in the rat model of hemorrhagic shock.

Methods

Rats were anesthetized and randomly assigned to one of four groups: (1) baseline, (2) shock, (3) 7.5% NaCl controls, and (4) 7.5% NaCl ALM. Animals were bled for 20 min (42% blood loss) and left in shock for 60 min before resuscitation with 0.3 ml intravenous bolus 7.5% NaCl ± ALM. Rats were sacrificed at 5, 10, 15, 30, and 60 min for rotation thromboelastometry and 15 and 60 min for ELISA analyses.

Results

After hemorrhagic shock, 7.5% NaCl failed to resuscitate and exacerbated coagulopathy and fibrinolysis. At 15 and 60 min, the activation as extrinsically-activated test using tissue factor (EXTEM) with aprotinin to inhibit fibrinolysis (APTEM) test showed little or no correction of fibrinolysis, indicating a plasmin-independent fibrinolysis. Clots also had ~ 60% lower fibrinogen (fibrin-based EXTEM activated test with platelet inhibitor cytochalasin D A10) and 36%-50% reduced fibrinogen-to-platelet ratio (11%-14% vs. 22% baseline). In contrast, 7.5% NaCl ALM resuscitated mean arterial pressure and attenuated hyperfibrinolysis and coagulopathy by 15 min. Correction was associated with lower plasma tissue factor, higher plasminogen activator inhibitor-1, and lower D-dimers (5% of controls at 60 min). Platelet selectin fell to undetectable levels in ALM animals, which may imply improved endothelial and platelet function during resuscitation.

Conclusions

Small-volume 7.5% NaCl resuscitation exacerbated coagulopathy and fibrinolysis that was not corrected by APTEM test. Fibrinolysis appears to be associated with altered fibrin structure during early clot formation and elongation. In contrast, 7.5% NaCl ALM rapidly corrected both coagulopathy and hyperfibrinolysis.

The effectiveness of prehospital hypertonic saline for hypotensive trauma patients: a systematic review and meta-analysis

Background

The optimal prehospital fluid for the treatment of hypotension is unknown. Hypertonic fluids may increase circulatory volume and mute the pro-inflammatory response of the body to injury and illness. The purpose of this systematic review is to determine whether in patients presenting with hypotension in the prehospital setting (population), the administration of hypertonic saline (intervention), compared to an isotonic fluid (control), improves survival to hospital discharge (outcome).

Methods

Searches were conducted in Medline, Embase, CINAHL, and CENTRAL from the date of database inception to November, 2016, and included all languages. Two reviewers independently selected randomized control trials of hypotensive human participants administered hypertonic saline in the prehospital setting. The comparison was isotonic fluid, which included normal saline, and near isotonic fluids such as Ringer’s Lactate. Assessment of study quality was done using the Cochrane Collaborations’ risk of bias tool and a fixed effect meta-analysis was conducted to determine the pooled relative risk of survival to hospital discharge. Secondary outcomes were reported for fluid requirements, multi-organ failure, adverse events, length of hospital stay, long term survival and disability.

Results

Of the 1160 non-duplicate citations screened, thirty-eight articles underwent full-text review, and five trials were included in the systematic review. All studies administered a fixed 250 ml dose of 7.5% hypertonic saline, except one that administered 300 ml. Two studies used normal saline, two Ringer’s Lactate, and one Ringer’s Acetate as control. Routine care co-interventions included isotonic fluids and colloids. Five studies were included in the meta-analysis (n = 1162 injured patients) with minimal statistical heterogeneity (I² = 0%). The pooled relative risk of survival to hospital discharge with hypertonic saline was 1.02 times that of patients who received isotonic fluids (95% Confidence Interval: 0.95, 1.10). There were no consistent statistically significant differences in secondary outcomes.

Conclusions

There was no significant difference in important clinical outcomes for hypotensive injured patients administered hypertonic saline compared to isotonic fluid in the prehospital setting. Hypertonic saline cannot be recommended for use in prehospital clinical practice for the management of hypotensive injured patients based on the available data.

PROSPERO registration # CRD42016053385.

Does small-volume resuscitation with crystalloids or colloids influence hemostasis and survival of rabbits subjected to lethal uncontrolled hemorrhage?

BACKGROUND

Prehospital, small-volume resuscitation of combat casualties with a synthetic colloid (6% hydroxyethyl starch [HES] 670/0.75) has been recommended when blood or blood components are unavailable. We studied hemostatic effects of a newer synthetic colloid (6% HES, 130/0.4) compared with either a natural colloid (albumin) or to crystalloids in an uncontrolled hemorrhage model.

METHODS

Spontaneously breathing New Zealand white rabbits (3.4 ± 0.1 kg) were anesthetized, instrumented, and subjected to a splenic injury with uncontrolled bleeding. Fifteen minutes after injury, rabbits were in shock (mean arterial pressure [MAP] = 26 ± 1.3 mm Hg, and received colloids (6% HES, 130/0.4 or 5% albumin at 15 mL/kg), or crystalloids (normal saline at 30 mL/kg or 5% hypertonic saline at 7.5 mL/kg) for resuscitation in two intravenous bolus injections (15 minutes apart) to raise their MAP to 65 mm Hg, n = 9/group. Animals were monitored for 2.5 hours or until death, and blood losses were measured. Blood samples were analyzed for arterial blood gas, complete blood count, and coagulation measures.

RESULTS

There were no differences among groups in baseline measures and initial hemorrhage volume (11.9 ± 0.6 mL/kg) at 15 minutes postinjury. Twenty minutes after fluid resuscitation (1 hour postinjury), MAP was higher, shock indices were lower, and blood pH was higher in colloids versus. crystalloids groups (p < 0.05). Administration of 6% HES 130/0.4 colloid produced the largest hemodilution (54% decrease in hematocrit, p < 0.05 vs. hypertonic saline). Activated partial thromboplastin time increased approximately 35% above baseline in all groups except in 6% HES 130/0.4 group in which it doubled. Clot strength was reduced (15%) only in the 6% HES 130/0.4 group. 6% HES 130/0.4 resuscitation produced the largest blood loss and 33% survival rate that was not different than the crystalloid groups. Albumin produced the best hemostatic and survival outcomes (78%).

CONCLUSION

Small-volume resuscitation with crystalloids appeared inadequate to treat hypovolemic shock and prevent death. 6% HES 130/0.4 was effective hemodynamically but detrimental to hemostasis. Albumin produced the best outcomes consistent with our previous observations. Further studies are needed to prove benefit of albumin solution as a possible resuscitation fluid for treating combat casualties at the point of injury.

Early and sustained vasopressin infusion augments the hemodynamic efficacy of restrictive fluid resuscitation and improves survival in a liver laceration model of hemorrhagic shock

BACKGROUND

Current management of hemorrhagic shock favors restrictive fluid resuscitation before control of the bleeding source. We investigated the additional effects of early and sustained vasopressin infusion in a swine model of hemorrhagic shock produced by liver laceration.

METHODS

Forty male domestic pigs (32-40 kg) had a liver laceration inflicted with an X-shaped blade clamp, 32 received a second laceration at minute 7.5, and 24 received two additional lacerations at minute 15. Using a two-by-two factorial design, animals were randomized 1:1 to receive vasopressin infusion (0.04 U/kg per minute) or vehicle intraosseously from minute 7 until minute 240 and 1:1 to receive isotonic sodium chloride solution (12 mL/kg) intravenously at minute 30 or no fluids.

RESULTS

Kaplan-Meier curves showed greater survival after vasopressin with isotonic sodium chloride solution (8/10) compared to vasopressin without isotonic sodium chloride solution (4/10), vehicle with isotonic sodium chloride solution (3/10), or vehicle without isotonic sodium chloride solution (3/10), but the differences were not statistically significant (p = 0.095 by log-rank test). However, logistic regression showed vasopressin to elicit a statistically significant benefit on survival (p = 0.042). Vasopressin augmented mean aortic pressure between 10 and 20 mm Hg without intensifying the rate of bleeding from liver laceration, which was virtually identical to that of vehicle-treated animals (33.9 ± 5.1 and 33.8 ± 4.8 mL/kg). Vasopressin increased systemic vascular resistance and reduced transcapillary fluid extravasation, augmenting the volume of isotonic sodium chloride solution retained (6.5 ± 2.7 vs 2.4 ± 2.0 mL/kg by minute 60). The cardiac output and blood flow to the myocardium, liver, spleen, kidney, small bowel, and skeletal muscle at minute 120 and minute 180 were comparable or higher in the vasopressin group.

CONCLUSIONS

Early and sustained vasopressin infusion provided critical hemodynamic stability during hemorrhagic shock induced by liver laceration and increased the hemodynamic efficacy of restrictive fluid resuscitation without intensifying bleeding or compromising organ blood flow resulting in improved 240-minute survival.

Low-volume resuscitation using polyethylene glycol-20k in a preclinical porcine model of hemorrhagic shock

INTRODUCTION

Polyethylene glycol-20k (PEG-20k) is highly effective for low-volume resuscitation (LVR) by increasing tolerance to the low-volume state. In our rodent shock model, PEG-20k increased survival and expanded the "golden hour" 16-fold compared to saline. The molecular mechanism is largely attributed to normalizations in cell and tissue fluid shifts after low-flow ischemia resulting in efficient microvascular exchange. The objective of this study was to evaluate PEG-20k as an LVR solution for hemorrhagic shock in a preclinical model.

METHODS

Anesthetized male Yorkshire pigs (30-40 kg) were hemorrhaged to a mean arterial pressure (MAP) of 35 to 40 mm Hg. Once lactate reached 7 mmol/L, either saline (n = 5) or 10% PEG-20k (n = 5) was rapidly infused at 10% calculated blood volume. The primary outcome was LVR time, defined by the time from LVR administration to the time when lactate again reached 7 mmol/L. Other outcomes measured included MAP, heart rate, cardiac output, mixed venous oxygen saturation, splanchnic blood flow, and hemoglobin.

RESULTS

Relative to saline, PEG-20k given after controlled hemorrhage increased LVR time by 16-fold, a conservative estimate given that the lactate never rose after LVR in the PEG-20k group. Survival was 80% for PEG-20k LVR compared to 0% for the saline controls (p < 0.05). Polyethylene glycol-20k also significantly decreased heart rate after hemorrhage and increased cardiac output, MAP, splanchnic flow, and mixed venous oxygen saturation. Falling hemoglobin concentrations suggested sizable hemodilution from fluid shifts into the intravascular compartment.

CONCLUSIONS

In a preclinical model of controlled hemorrhagic shock, PEG-20k-based LVR solution increased tolerance to the shock state 16-fold compared to saline. Polyethylene glycol-20k is a superior crystalloid for LVR that may increase safe transport times in the prehospital setting and find use in hospital emergency departments and operating rooms for patients awaiting volume replacement or normalization of cell, tissue, and compartment fluid volumes.

Inhibition of Neutrophils by Hypertonic Saline Involves Pannexin-1, CD39, CD73, and Other Ectonucleotidases

Hypertonic saline (HS) resuscitation has been studied as a possible strategy to reduce polymorphonuclear neutrophil (PMN) activation and tissue damage in trauma patients. Hypertonic saline blocks PMNs by adenosine triphosphate (ATP) release and stimulation of A2a adenosine receptors. Here, we studied the underlying mechanisms in search of possible reasons for the inconsistent results of recent clinical trials with HS resuscitation. Purified human PMNs or PMNs in whole blood were treated with HS to simulate hypertonicity levels found after HS resuscitation (40 mmol/L beyond isotonic levels). Adenosine triphosphate release was measured with a luciferase assay. Polymorphonuclear neutrophil activation was assessed by measuring oxidative burst. The pannexin-1 (panx1) inhibitor panx1 and the gap junction inhibitor carbenoxolone (CBX) blocked ATP release from PMNs in purified and whole blood preparations, indicating that HS releases ATP via panx1 and gap junction channels. Hypertonic saline blocked N-formyl-Met-Leu-Phe-induced PMN activation by 40% in purified PMN preparations and by 60% in whole blood. These inhibitory effects were abolished by panx1 but only partially reduced by CBX, which indicates that panx1 has a central role in the immunomodulatory effects of HS. Inhibition of the ectonucleotidases CD39 and CD73 abolished the suppressive effect of HS on purified PMN cultures but only partially reduced the effect of HS in whole blood. These findings suggest redundant mechanisms in whole blood that may strengthen the immunomodulatory effect of HS in vivo. We conclude that HS resuscitation exerts anti-inflammatory effects that involve panx1, CD39, CD73, and other ectonucleotidases, which produce the adenosine that blocks PMNs by stimulating their A2a receptors. Our findings shed new light on the immunomodulatory mechanisms of HS and suggest possible new strategies to improve the clinical efficacy of hypertonic resuscitation.

Prehospital Resuscitation of Traumatic Hemorrhagic Shock with Hypertonic Solutions Worsens Hypocoagulation and Hyperfibrinolysis

Impaired hemostasis frequently occurs after traumatic shock and resuscitation. The prehospital fluid administered can exacerbate subsequent bleeding and coagulopathy. Hypertonic solutions are recommended as first-line treatment of traumatic shock; however, their effects on coagulation are unclear. This study explores the impact of resuscitation with various hypertonic solutions on early coagulopathy after trauma. We conducted a prospective observational subgroup analysis of large clinical trial on out-of-hospital single-bolus (250 mL) hypertonic fluid resuscitation of hemorrhagic shock trauma patients (systolic blood pressure, ≤70 mmHg). Patients received 7.5% NaCl (HS), 7.5% NaCl/6% Dextran 70 (HSD), or 0.9% NaCl (normal saline [NS]) in the prehospital setting. Thirty-four patients were included: 9 HS, 8 HSD, 17 NS. Treatment with HS/HSD led to higher admission systolic blood pressure, sodium, chloride, and osmolarity, whereas lactate, base deficit, fluid requirement, and hemoglobin levels were similar in all groups. The HSD-resuscitated patients had higher admission international normalized ratio values and more hypocoagulable patients, 62% (vs. 55% HS, 47% NS; P < 0.05). Prothrombotic tissue factor was elevated in shock treated with NS but depressed in both HS and HSD groups. Fibrinolytic tissue plasminogen activator and anti-fibrinolytic plasminogen activator inhibitor type 1 were increased by shock but not thrombin-activatable fibrinolysis inhibitor. The HSD patients had the worst imbalance between procoagulation/anticoagulation and profibrinolysis/antifibrinolysis, resulting in more hypocoagulability and hyperfibrinolysis. We concluded that resuscitation with hypertonic solutions, particularly HSD, worsens hypocoagulability and hyperfibrinolysis after hemorrhagic shock in trauma through imbalances in both procoagulants and anticoagulants and both profibrinolytic and antifibrinolytic activities.

Collider bias in trauma comparative effectiveness research: the stratification blues for systematic reviews

BACKGROUND

Collider bias, or stratifying data by a covariate consequence rather than cause (confounder) of treatment and outcome, plagues randomised and observational trauma research. Of the seven trials of prehospital hypertonic saline in dextran (HSD) that have been evaluated in systematic reviews, none found an overall between-group difference in survival, but four reported significant subgroup effects. We hypothesised that an avoidable type of collider bias often introduced inadvertently into trauma comparative effectiveness research could explain the incongruous findings.

METHODS

The two most recent HSD trials, a single-site pilot and a multi-site pivotal study, provided data for a secondary analysis to more closely examine the potential for collider bias. The two trials had followed the a priori statistical analysis plan to subgroup patients by a post-randomisation covariate and well-established surrogate for bleeding severity, massive transfusion (MT), ≥ 10 unit of red blood cells within 24h of admission. Despite favourable HSD effects in the MT subgroup, opposite effects in the non-transfused subgroup halted the pivotal trial early. In addition to analyzing the data from the two trials, we constructed causal diagrams and performed a meta-analysis of the results from all seven trials to assess the extent to which collider bias could explain null overall effects with subgroup heterogeneity.

RESULTS

As in previous trials, HSD induced significantly greater increases in systolic blood pressure (SBP) from prehospital to admission than control crystalloid (p=0.003). Proportionately more HSD than control decedents accrued in the non-transfused subgroup, but with paradoxically longer survival. Despite different study populations and a span of over 20 years across the seven trials, the reported mortality effects were consistently null, summary RR=0.99 (p=0.864, homogeneity p=0.709).

CONCLUSIONS

HSD delayed blood transfusion by modifying standard triggers like SBP with no detectable effect on survival. The reported heterogeneous HSD effects in subgroups can be explained by collider bias that trauma researchers can avoid by improved covariate selection and data capture strategies.

Hemodynamic responses elicited by systemic injections of isotonic and hypertonic saline in hemorrhaged rats

PURPOSE

The objectives of this study were (i) to characterize the hemodynamic responses caused by controlled hemorrhage (HEM) in pentobarbital-anesthetized rats, and (ii) to determine the responses elicited by systemic bolus injections of isotonic saline (0.15M) or hypertonic saline (3M) given 5min after completion of HEM.

RESULTS

Controlled HEM (4.3±0.2ml/rat at 1.5ml/min) resulted in a pronounced and sustained fall in mean arterial blood pressure (MAP) to about 40mmHg. The fall in MAP was associated with a reduction in hindquarter vascular resistance (HQR) but no changes in renal (RR) or mesenteric (MR) vascular resistances. Systemic injections of isotonic saline (96-212μmol/kg i.v., in 250-550μl) did not produce immediate responses but promoted the recovery of MAP to levels below pre-HEM values. Systemic injections of hypertonic saline (750-3000μmol/kg, i.v., in 250-550μl) produced immediate and pronounced falls in MAP, RR, MR and especially HQR of 30-120s in duration. However, hypertonic saline prompted a full recovery of MAP, HQR and RR to pre-HEM levels and an increase in MR to levels above pre-HEM values.

CONCLUSIONS

This study demonstrates that (i) HEM induced a pronounced fall in MAP which likely involved a fall in cardiac output and HQR, (ii) isotonic saline did not fully normalize MAP, and (iii) hypertonic saline produced dramatic initial responses, and promoted normalization of MAP probably by restoring blood volume and cardiac output through sequestration of fluid from intracellular compartments.

The Bellamy challenge: it's about time

In 1984, Col. Ronald Bellamy launched a worldwide challenge to develop a new resuscitation fluid to aid survival after catastrophic blood loss on the battlefield. In 1996, after careful compromise among need, cube weight and efficacy, the US military and later coalition forces adopted 6% hetastarch (HES) fluids for early resuscitation. In the intervening years, evidence has amassed indicating that the HES fluids may not be safe, and in June 2013 the US Food and Drug Administration issued a warning that HES solutions should not be used to treat patients with hypovolaemia or the critically ill. We review the unique challenges of early battlefield resuscitation, why the 'Bellamy challenge' remains open and discuss a number of forward-looking strategies that may help to solve the problem. The first two pillars of resuscitation that we believe have not been adequately addressed are rescuing and stabilising the heart (and brain) and the vascular system. The 'ideal' resuscitation fluid needs to nurture the heart and body slowly back to health, and not 'shock' it a second time with unnatural colloids or large volumes of unphysiological saline-based solutions.