Clinical review: Hypertonic saline resuscitation in sepsis

Effects of resuscitation with crystalloid fluids on cardiac function in patients with severe sepsis

Background

The use of hypertonic crystalloid solutions, including sodium chloride and bicarbonate, for treating severe sepsis has been much debated in previous investigations. We have investigated the effects of three crystalloid solutions on fluid resuscitation in severe sepsis patients with hypotension.

Methods

Ninety-four severe sepsis patients with hypotension were randomly assigned to three groups. The patients received the following injections within 15 min at initial treatment: Ns group (n = 32), 5 ml/kg normal saline; Hs group (n = 30), with 5 ml/kg 3.5% sodium chloride; and Sb group (n = 32), 5 ml/kg 5% sodium bicarbonate. Cardiac output (CO), systolic blood pressure, mean arterial pressure (MAP), body temperature, heart rate, respiratory rate and blood gases were measured.

Results

There were no differences among the three groups in CO, MAP, heart rate or respiratory rate during the 120 min trial or the 8 hour follow-up, and no significant differences in observed mortality rate after 28 days. However, improvement of MAP and CO started earlier in the Sb group than in the Ns and Hs groups. Sodium bicarbonate increased the base excess but did not alter blood pH, lactic acid or [HCO₃]^- values; and neither 3.5% hypertonic saline nor 5% sodium bicarbonate altered the Na⁺, K⁺, Ca²⁺ or Cl^- levels.

Conclusion

All three crystalloid solutions may be used for initial volume loading in severe sepsis, and sodium bicarbonate confers a limited benefit on humans with severe sepsis.

Trial registration

ISRCTN36748319.

Sodium chloride inhibits cytokine production by lipopolysaccharide-stimulated human neutrophils and mononuclear cells

Hypertonic sodium chloride (NaCl) solution has been shown to have beneficial effects on patients with hypovolemic shock. Therapy with hypertonic saline seems to neutralize or minimize the deleterious immune responses in these patients. In this study, we addressed how hypertonic NaCl solution affects the release of cytokines by isolated human blood cells. We examined the effect of NaCl on tumor necrosis factor (TNF)-alpha, interleukin (IL)-8, IL-1beta, and IL-1 receptor antagonist released by human neutrophils and mononuclear cells under nonstimulated and LPS-stimulated conditions. Cells isolated from healthy donors were cultured in the presence or absence of lipopolysaccharide (LPS). Cytokine concentrations were measured by enzyme-linked immunosorbent assay in culture supernatants. The addition of NaCl lowered the production of IL-8, TNF-alpha, and IL-1 receptor antagonist by neutrophils, and IL-8 and IL-1beta by mononuclear cells stimulated with LPS. This effect was not observed when NaCl solution was replaced by a solution of potassium iodide in the same conditions. The decreased production of cytokines in the presence of hypertonic saline was not caused by cell death. Our findings support the proposal that the modulation of leukocyte inflammatory response by NaCl occurs by an electrolyte-specific effect in addition to the hyperosmolarity. Furthermore, the results of this study support the therapeutic use of appropriate doses of i.v. NaCl solutions to minimize tissue injury characterized by neutrophil and mononuclear cell infiltration into tissues in post-traumatic patients.

Effect of glycine on the calcium signal of thrombin-stimulated platelets

In treatment of hemorrhagic shock, small-volume infusion of 7.5% NaCl gives immediate hemodynamic improvement, but in vitro experiments suggest it depresses the hemostatic system. Since previous reports showed that hyperosmotic glycine solutions preserved the platelet function better than hyperosmotic NaCl solutions, we investigated whether glycine changes the intracellular calcium ([Ca]i) signal. Platelets were incubated in hyperosmotic solutions containing sodium glycine or glycine base and stimulated with 0.1 IU/ml thrombin. [Ca]i increases were compared with an isosmotic control. Platelets incubated in zero calcium/EGTA were used to study separately the effect of glycine on calcium mobilization from intracellular stores and extracellular calcium entry. When NaCl was replaced by sodium glycine, the [Ca]i increase produced by thrombin was enhanced, because the calcium entry increased without changes in the mobilization of stored calcium. The addition of 50 mmol/l glycine base to the HEPES-buffered media increases the thrombin-induced entry of calcium or manganese. This study demonstrates that hyperosmotic glycine solutions increase the entry of calcium. This effect contrasts with the impairment of the thrombin-induced calcium signals by NaCl. The addition of low amounts of glycine in resuscitation solutions would be useful to reduce dysfunctional inflammatory responses without the risk of bleeding; however, concentrated solutions could cause toxic effects.

VASOPRESSIN MEDIATES THE PRESSOR EFFECT OF HYPERTONIC SALINE SOLUTION IN ENDOTOXIC SHOCK

The administration of lipopolysaccharide (LPS) to experimental animals results in a septic shock-like syndrome characterized by hypotension, and the hemodynamic management includes the restoration of adequate tissue perfusion by administration of resuscitation fluids to achieve an effective circulating volume. In the present study, we sought to investigate the effects of hypertonic saline solution administration on vasopressin secretion and mean arterial pressure in endotoxic shock. The pressor response to isotonic saline solution (0.9% sodium chloride) or hypertonic saline (7.5% sodium chloride, 4 mL/kg i.v.) was evaluated 4 h after LPS (1.5 mg/kg) administration. At this moment, plasma vasopressin did not differ from control; however, the blood pressure was lower in the LPS-treated group. The hypertonic saline administration was followed by an immediate recovery of blood pressure and also by an increase in plasma vasopressin levels compared with isotonic saline solution. The vasopressin V1 receptor antagonist (10 microg/kg, i.v., 5 min before infusion) blocked the pressor response to hypertonic saline solution. These data suggest that the recovery of blood pressure after hypertonic saline solution administration during endotoxic shock is mediated by vasopressin secretion.

The effects of 10% hypertonic saline, 0.9% saline and hydroxy ethyl starch infusions on hydro-electrolyte status and adrenal function in healthy conscious dogs

The purpose of this study was to investigate the influence of different saline and colloid solutions on adrenal steroid secretion in dogs. Six healthy male Beagles underwent three infusion cycles: 10 min infusion of 30 ml/kg of NaCl 0.9%, 5 ml/kg of hydroxy ethyl starch, or 5 ml/kg of NaCl 10%. Plasma osmolality, hematocrit, total solids, cortisol and aldosterone levels were measured at 0, 5, 15, 30, 60, 120, 180 and 240 min after beginning infusion. Plasma ACTH levels were measured at 0, 15 and 240 min. An identical timing of sampling was applied during a control session omitting the fluid infusion. Osmolality, sodium, chloride and cortisol levels were found to be significantly higher with hypertonic saline solute compared to control. All fluid infusions lead to lowered plasma potassium, hematocrit, total solids and aldosterone values. ACTH concentrations did not show significant changes with any of the infusion cycles. The increase in cortisol levels suggests that hypertonic saline infusion could be interesting in critical care resuscitation, particularly in patients who are suffering from relative adrenal insufficiency.

Paradoxically enhanced heart tolerance to ischaemia in type 1 diabetes and role of increased osmolarity

There is considerable controversy regarding the tolerance of diabetic hearts to ischaemia and the underlying mechanisms responsible for the increased heart tolerance to ischamia remain uncertain. In the present study, we observed, in vitro, type 1 diabetic heart responses to ischaemia and reperfusion at different degrees of hyperglycaemia. In addition, the possible role of increased osmolarity in cardioprotection due to hyperglycaemia was evaluated. Hearts from 3 week streptozocin-induced diabetic rats were isolated and perfused in a Langendorff apparatus and subjected to 30 min ischaemia and 30 min reperfusion. Cardiac function and the electrocardiogram were recorded. Myocardial content of osmolarity associated heat shock protein (hsp) 90, heme oxygenase (HO)-1 and anti-oxidant enzymes were determined in diabetic or hyperosmotic solution-perfused hearts using western blot. The hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG; 2 x 10(-7) mol/L) or the nitric oxide synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester (1 x 10(-5) mol/L) was added to the perfusate to observe the effects of hsp90 inhibition and hsp90-associated endothelial NOS on ischaemic responses of diabetic hearts. Compared with normal control rats, diabetic hearts with severe hyperglycaemia (blood glucose > 20 mmol/L) showed markedly improved postischaemic heart function with fewer reperfusion arrhythmias. Mild hyperglycaemia (< 12 mmol/L) exhibited no significant cardioprotection. Elevated expression of hsp90 accompanied the enhanced resistance to ischaemia in diabetic hearts, which was abrogated by 17-AAG. In the presence of the NOS inhibitor, heart function was preserved, whereas reperfusion arrhythmias were increased in diabetes. Diabetic hearts also had markedly elevated HO-1 and catalase, with no significant change in superoxide dismutase. Hyperosmotic perfusion with glucose or mannitol also increased myocardial hsp90 and catalase. The present findings reveal that heart resistance to ischaemia is increased in short-term type 1 diabetes with severe hyperglycaemia. Elevated osmolarity caused by significant hyperglycaemia may contribute to the enhanced myocardial activity against oxidative injury during ischaemia and reperfusion.

Fluid resuscitation and the septic kidney

Acute renal failure is a common complication of sepsis in the critically ill patient. Fluid resuscitation is considered a cornerstone for preservation of function in the septic kidney. This is generally based on the assumption that fluid therapy will restore and maintain adequate renal blood flow. This principle, however, has not yet been formally evaluated in humans. Thus, it remains unclear how fluid therapy may affect renal blood flow in septic acute renal failure. Further, there is new evidence to imply that the choice, timing and amount of fluid used for resuscitation in sepsis may have a direct impact on kidney function. Thus, in this editorial, we consider the relevant literature and more recent insights into the effect of fluid resuscitation on the septic kidney.

Small volume of hypertonic saline as the initial fluid replacement in experimental hypodynamic sepsis

INTRODUCTION

We conducted the present study to examine the effects of hypertonic saline solution (7.5%) on cardiovascular function and splanchnic perfusion in experimental sepsis.

METHODS

Anesthetized and mechanically ventilated mongrel dogs received an intravenous infusion of live Escherichia coli over 30 minutes. After 30 minutes, they were randomized to receive lactated Ringer's solution 32 ml/kg (LR; n = 7) over 30 minutes or 7.5% hypertonic saline solution 4 ml/kg (HS; n = 8) over 5 minutes. They were observed without additional interventions for 120 minutes. Cardiac output (CO), mean arterial pressure (MAP), portal and renal blood flow (PBF and RBF, respectively), gastric partial pressure of CO2 (pCO2; gas tonometry), blood gases and lactate levels were assessed.

RESULTS

E. coli infusion promoted significant reductions in CO, MAP, PBF and RBF (approximately 45%, 12%, 45% and 25%, respectively) accompanied by an increase in lactate levels and systemic and mesenteric oxygen extraction (sO2ER and mO2ER). Widening of venous-arterial (approximately 15 mmHg), portal-arterial (approximately 18 mmHg) and gastric mucosal-arterial (approximately 55 mmHg) pCO2 gradients were also observed. LR and HS infusion transiently improved systemic and regional blood flow. However, HS infusion was associated with a significant and sustained reduction of systemic (18 +/- 2.6 versus 38 +/- 5.9%) and mesenteric oxygen extraction (18.5 +/- 1.9 versus 36.5 +/- 5.4%), without worsening other perfusional markers.

CONCLUSION

A large volume of LR or a small volume of HS promoted similar transient hemodynamic benefits in this sepsis model. However, a single bolus of HS did promote sustained reduction of systemic and mesenteric oxygen extraction, suggesting that hypertonic saline solution could be used as a salutary intervention during fluid resuscitation in septic patients.

Effect of fluid resuscitation on ryanodine receptor in macaques with endotoxic shock

OBJECTIVE

Our recent study demonstrated that sodium bicarbonate improved cardiac function in macaque models with early-phase endotoxic shock. In the present study, we investigated further the ryanodine receptor/calcium release-channel (RyR) and calcium pump after fluid resuscitation of macaques with early-phase endotoxic shock.

METHODS

Twenty-four anaesthetised macaques were assigned to four groups. Nineteen animals were given an intravenous dose of 2.8 mgkg(-1) lipopolysaccharide (LPS). Sixty minutes after the LPS challenge, the animals were given (i) 5 mLkg(-1) normal saline (Ns group, n = 6), (ii) 5 mLkg(-1) of 5% sodium bicarbonate (Sb group, n = 6) or (iii) 5 mLkg(-1) of 3.5% hypertonic sodium chloride (Hs group, n = 7). The control group (Co group, n = 5) received 1 mLkg(-1) normal saline and then with 5 mLkg(-1) normal saline 60 min later.

RESULTS

Endotoxin produced a reduction of the density of RyR but did not alter the affinity of RyR. Compared with normal saline, sodium bicarbonate or hypertonic saline induced a restoration of density of RyR but did not influence the affinity of RyR and the calcium pump.

CONCLUSION

Up-regulation of RyR performance in myocardium following administration of sodium bicarbonate contributes to the improvement of cardiac function in macaques in the early phase of endotoxic shock.

The Synergistic Effects of Pentoxifylline on Systemic and Regional Perfusion After Hemorrhage and Hypertonic Resuscitation

Small volumes of hypertonic saline solution ([HS] 7.5% NaCl) produce systemic and microcirculatory benefits in hemorrhaged animals. Pentoxifylline (PTX) has beneficial effects when administrated after hemorrhagic shock. We tested the hypothesis that the combination of HS and PTX in the initial treatment of hemorrhagic shock provides synergistic hemodynamic benefits. Twenty-four dogs were bled to a target arterial blood pressure of 40 mm Hg and randomized into 3 groups: lactated Ringer's solution (33 mL/kg; n = 6); HS (7.5% NaCl 4 mL/kg; n = 9); and HS+PTX (7.5% NaCl 4 mL/kg + PTX 15 mg/kg; n = 9). Systemic hemodynamics were measured by Swan-Ganz and arterial catheters. Gastric mucosal-arterial Pco2 gradient (D(g-a)Pco2; gas tonometry), portal vein blood flow (ultrasonic flowprobe), and systemic and regional O2-derived variables were also evaluated. HS induced a partial increase in mean arterial blood pressure, cardiac output, and portal vein blood flow. In the HS+PTX group, we observed a significant, but transitory, increase in systemic oxygen delivery (180 +/- 17 versus 141 +/- 13 mL/min) in comparison to HS alone. PTX infusion during hypertonic resuscitation promoted a significant reduction in D(g-a)Pco2 (41.8 +/- 4.8 to 25.7 +/- 3.9 mm Hg) when compared with isolated HS infusion (48.2 +/- 6.4 to 39.4 +/- 5.5 mm Hg). We conclude that PTX as an adjunct drug during hypertonic resuscitation improves cardiovascular performance and gastric mucosal oxygenation.

Local and systemic effects of hypertonic solution (NaCl 7.5%) in experimental acute pancreatitis

OBJECTIVES

Severe acute pancreatitis (AP) is characterized by hemodynamic alterations and a systemic inflammatory response, leading to a high mortality rate. Treatment of hemorrhagic shock with hypertonic saline solutions significantly reduces mortality through an improvement in the hemodynamic conditions and possibly by an anti-inflammatory effect. Therefore, hypertonic solutions could be effective in AP.

METHODS

Wistar rats were divided in 4 groups: group C, control, without AP; group NT, AP, without treatment; group NS, treatment with normal saline solution (NaCl 0.9%) 1 hour after AP; group HTS, treatment with hypertonic saline solution (NaCl 7.5%) 1 hour after AP. AP was induced by injection of 2.5% sodium taurocholate into the pancreatic duct. Mean arterial blood pressure (MAP) and heart rate were recorded at 0 and 2, 4, 24, and 48 hours after AP. After induction of AP, animals were killed at 2, 12, 24, and 48 hours for serum amylase, interleukin (IL)-6, and IL-10 analysis, pancreatic tissue culture and histologic analysis, oxidation and phosphorylation of liver mitochondria, pulmonary myeloperoxidase activity (MPO), and mortality study.

RESULTS

In animals of groups NS and NT, a significant decrease of MAP was observed 48 hours after AP (NS: 91 +/- 3 mm Hg; NT: 89 +/- 3 mm Hg) compared with baseline (C: 105 +/- 2 mm Hg) and to HTS group (HTS: 102 +/- 2 mm Hg; P < 0.05). In animals of group NT, NS, and HTS, serum IL-6 and IL-10 levels were significantly higher at 2 hours after AP compared with the control group. However, IL-6 levels at 12 hours after AP and IL-10 levels at 2 and 12 hours after AP were significant lower in group HTS compared with NS and NT groups (P < 0.05). In group HTS, a decrease of pulmonary MPO activity and of pancreatic infection was observed 24 hours after AP compared with NT and NS groups (P < 0.05). A significant reduction on pancreatic acinar necrosis and mitochondrial dysfunction was observed after 48 hours of AP in animals of group HTS compared with groups NT and NS (P < 0.05). A significant reduction on mortality was observed in HTS (0/14) compared with NS (6/17; 35%) and NT (7/20; 35%).

CONCLUSIONS

The administration of hypertonic saline solution in experimental AP attenuated hemodynamic alterations, decreased inflammatory cytokines, diminished systemic lesions and pancreatic acinar necrosis, prevented pancreatic infection, and reduced the mortality rate.

Microvascular effects following treatment with polyethylene glycol-albumin in lipopolysaccharide-induced endotoxemia

OBJECTIVE

To determine whether resuscitation with polyethylene glycol conjugated bovine serum albumin (2.5% weight/volume) infused at 16 mL/kg/hr (PEG-BSA-16) or at 24 mL/kg/hr (PEG-BSA-24) for 1 hr improves microcirculatory conditions in endotoxemia compared with dextran 70 (6% weight/volume) infused at 24 mL/kg/hr (Dex).

DESIGN

Prospective study.

SETTING

University research laboratory.

SUBJECTS

Male Golden Syrian hamsters.

INTERVENTIONS

Hamsters implemented with a skinfold window chamber were given an intravenous injection of lipopolysaccharide and resuscitated within 10 mins with Dex, PEG-BSA-16, or PEG-BSA-24.

MEASUREMENTS AND MAIN RESULTS

Hamsters were observed during 24 hrs after lipopolysaccharide injection. Systemic variables measured included mean arterial pressure, heart rate, and systemic arterial blood gas. Microvascular function was characterized by measuring vessel diameter; red blood cell velocity; functional capillary density (FCD); P(O2) in arterioles, venules, and tissue; and perivascular nitric oxide concentration 6 hrs after lipopolysaccharide injection. At 6 hrs, animals with no treatment had the lowest FCD (6.7 +/- 5.7% of baseline). PEG-BSA provided significantly improved microvascular conditions as shown by restoration of FCD. Recovery of FCD was related to improved microvascular flow and perivascular and tissue P(O2), normalization of shear rate, and decreased perivascular nitric oxide concentration. These effects were related to improved fluid retention using PEG-BSA-24 as evidenced by the significantly lower hematocrit at 24 hrs after resuscitation. Nitric oxide at 6 hrs after induction of sepsis achieved perivascular millimolar concentrations, which were reduced to normal values by PEG-BSA-24 treatment. At 6 hrs there were significant differences in FCD, tissue P(O2), and perivascular nitric oxide concentration following PEG-BSA treatment by comparison with Dex treatment, although there were no differences in systemic variables between Dex and PEG-BSA groups.

CONCLUSIONS

PEG-BSA produces improved microcirculatory conditions in the treatment of endotoxemia when compared with dextran 70.

Augmentation of hospital critical care capacity after bioterrorist attacks or epidemics: recommendations of the Working Group on Emergency Mass Critical Care

The Working Group on Emergency Mass Critical Care was convened by the Center for Biosecurity of the University of Pittsburgh Medical Center and the Society of Critical Care Medicine to provide recommendations to hospital and clinical leaders regarding the delivery of critical care services in the wake of a bioterrorist attack resulting in hundreds or thousands of critically ill patients. In these conditions, traditional hospital and clinical care standards in general, and critical care standards in particular, likely could no longer be maintained, and clinical guidelines for U.S. hospitals facing these situations have not been developed. The Working Group offers recommendations for this situation.

Effects of different resuscitation fluids on tissue blood flow and oxidant injury in experimental rhabdomyolysis

OBJECTIVE

This study was performed to evaluate the effects of 0.9% saline (SAL), 0.9% saline + sodium bicarbonate + mannitol (SAL/BIC/MAN), and hypertonic saline-dextran (HSD) on hemodynamic variables, tissue blood flow, and oxidant injuries in experimental traumatic rhabdomyolysis (TR) in rats subjected allogeneic muscle extract infusion.

DESIGN

Prospective, randomized, experimental.

SETTING

Physiology experiment laboratory.

SUBJECTS

Male Sprague-Dawley rats, weighing 250-300 g.

INTERVENTIONS

All groups (n = 8 each) underwent femoral artery and vein catheterization. The animals in the TR, SAL, SAL/BIC/MAN, and HSD groups received an infusion of 2 mL of autologous muscle extract for 60 mins. After autologous muscle extract infusion, the SAL and HSD groups received 30 mL/kg 0.9% saline for 30 mins or 4 mL/kg HSD for 5 mins, respectively. The SAL/BIC/MAN group received 30 mL/kg 0.9% saline for 30 mins plus a bolus of 1 g/kg mannitol and a bolus of 2 mEq/kg sodium bicarbonate diluted in 1 mL of saline. At 2 hrs of autologous muscle extract infusion, erythrocyte flows in liver and kidney were measured by using a laser Doppler flowmeter. Then, blood samples and kidney and liver biopsies were taken to measure levels of glutathione and malondialdehyde.

MEASUREMENTS AND MAIN RESULTS

TR caused decreases in mean arterial pressure, tissue blood flow, and tissue glutathione and an increase in malondialdehyde. Rats in the HSD group had significant metabolic acidosis. SAL resuscitation did not correct tissue blood flow and prevent oxidant injury. HSD increased tissue blood flow, mean arterial pressure, and liver and kidney glutathione and decreased serum, liver, and kidney malondialdehyde. SAL/BIC/MAN resuscitation corrected all oxidant damage variables but did not increase tissue blood flow. SAL/BIC/MAN preserved serum malondialdehyde and liver glutathione better than the HSD did.

CONCLUSIONS

HSD prevented oxidant injury and restored tissue blood flow but increased metabolic acidosis that followed autologous muscle extract infusion. SAL/BIC/MAN seems to be more effective than HSD in decreasing oxidant injury. Further research on the effects of the solute overload and metabolic acidosis due to HSD resuscitation on renal function in experimental rhabdomyolysis is warranted.

Beneficial effects of hypertonic saline/dextran on early survival in porcine endotoxin shock

BACKGROUND

Hypertonic saline/dextran (HSD) has been shown to have beneficial effects in haemorrhagic shock. These effects, with improved haemodynamics and organ perfusion, would in theory also be of benefit in septic shock. However, this is less studied. We have therefore further evaluated the effect of additional treatment with HSD in a porcine endotoxin shock model.

METHODS

Sixteen anaesthetized pigs were used. A continuous infusion of endotoxin (LPS EC) was increased stepwise during 30 min to a rate of 5 microg/kg/h. The infusion was discontinued after 3 h and the animals were observed for another 2 h. The animals received continuous basal fluid resuscitation with isotonic Ringer's glucose 2.5% at a rate of 20 ml/kg/h throughout the experiment. After 1 h of endotoxin infusion, the animals were randomized to additional treatment with HSD, 4 ml/kg over 5 min, or the same volume of isotonic saline. Every 30 min, haemodynamics and mixed venous saturation (SvO2) were measured via a pulmonary artery catheter. Regional blood flow rates were measured continuously by perivascular ultrasonic flow probes. The metabolic response was measured by arterial blood gas analysis.

RESULTS

The endotoxin put all animals into a progressive hypodynamic circulatory shock during the experiment. Treatment with HSD improved survival rate to 8/8 compared with controls 3/8. There was a transient circulatory recovery with improved central and regional haemodynamics, accompanied by stabilized metabolic response.

CONCLUSION

Treatment with additional HSD improves survival in an early phase of endotoxin shock. Generally improved haemodynamics and oxygenation of peripheral tissues are suggested as possible mechanisms.

Small volume hypertonic resuscitation of circulatory shock

Small volume hypertonic resuscitation is a relatively new conceptual approach to shock therapy. It was originally based on the idea that a relatively large blood volume expansion could be obtained by administering a relatively small volume of fluid, taking advantage of osmosis. It was soon realized that the physiological vasodilator property of hypertonicity was a useful byproduct of small volume resuscitation in that it induced reperfusion of previously ischemic territories, even though such an effect encroached upon the malefic effects of the ischemia-reperfusion process. Subsequent research disclosed a number of previously unsuspected properties of hypertonic resuscitation, amongst them the correction of endothelial and red cell edema with significant consequences in terms of capillary blood flow. A whole set of actions of hypertonicity upon the immune system are being gradually uncovered, but the full implication of these observations with regard to the clinical scenario are still under study. Small volume resuscitation for shock is in current clinical use in some parts of the world, in spite of objections raised concerning its safety under conditions of uncontrolled bleeding. These objections stem mainly from experimental studies, but there are few signs that they may be of real clinical significance. This review attempts to cover the earlier and the more recent developments in this field.

Management following resuscitation from cardiac arrest: Recommendations from the 2003 Rocky mountain critical care conference

PURPOSE

To propose a strategy for the management of patients admitted to critical care units after resuscitation from cardiac arrest.

SOURCE

Prior to the conference relevant studies were identified via literature searches and brief reviews circulated on the following topics: glucose and blood pressure management; therapeutic hypothermia; prearrest outcome prediction; post-arrest outcome prediction; and management of myocardial ischemia. Two days were devoted to assessing evidence and developing a management strategy at the conference. Consensus opinion of conference participants [intensive care unit (ICU) physicians] was used when high grade evidence was unavailable. Additional literature searches and data grading were performed post-conference.

PRINCIPAL FINDINGS

High grade evidence was lacking in most areas. Specific goals of treatment were proposed for: general care; neurologic care; respiratory care; cardiac care; and gastrointestinal care. There was adequate evidence to recommend therapeutic hypothermia for comatose patients who had witnessed ventricular fibrillation or ventricular tachycardia arrests. Conference participants supported extending therapeutic hypothermia to other presenting rhythms in selected circumstances. Additional goals included mean arterial pressure 80 to 100 mmHg, glucose 5 to 8 mmol.L(-1) using insulin infusions, and PaO(2) > 100 mmHg for the first 24 hr. Absent withdrawal to pain 72 hr after resuscitation should prompt consideration of palliative care. The level of evidence for other recommendations was low.

CONCLUSIONS

The proposed management strategy represents an approach to manage patients in the ICU following resuscitation from cardiac arrest. Most of the recommendations are based on low grade evidence. Additional research is needed to improve the evidence base. A standard post-arrest management strategy could help facilitate future research.

Osmotic regulation of cell function and possible clinical applications

Inflammation and immunosuppression can cause acute respiratory distress syndrome, multiple organ failure, and sepsis, all of which are lethal posttraumatic complications in trauma patients. Prevention of the inflammation and immunosuppression has been a main focus of trauma researcher for many years. Recently, hypertonic resuscitation has attracted attention as a possible therapeutic approach to counteract such deleterious immune responses in trauma patients. We have begun to understand how hypertonic fluids affect immune cell signaling, and a number of experimental and clinical studies have started to reveal valuable information on the clinical efficacy and the limitations of hypertonic resuscitation fluids. Knowledge of how osmotic cues regulate immune cell function will enable us to fully exploit the clinical potential of hypertonic resuscitation to reduce inflammatory and anergic complications in trauma patients.

Bench-to-bedside review: Resuscitation in the emergency department

Over the past decade the practice of acute resuscitation and its monitoring have undergone significant changes. Utilization of noninvasive mechanical ventilation, goal-directed therapy, restricted fluid volume, blood transfusion and minimally invasive technology for monitoring tissue oxygenation have changed the practice of acute resuscitation. Early diagnosis and definitive treatment of the underlying cause of shock remains the mainstay for survival after successful resuscitation. Patient-centered outcome end-points, in addition to survival, are being utilized to appraise the effectiveness of treatment. Application of medical ethics to the ever changing practice of acute resuscitation has also become a societal expectation.

Hypertonic saline resuscitation in sepsis

The review by Oliveira and colleagues on the subject of hypertonic saline resuscitation in sepsis (included in the present issue) suggests possible benefits for hypertonic saline. There is a firm experimental basis for the actions of hypertonic saline/hyperoncotic solutions in hemorrhagic hypotension, which include expansion of blood volume, improvement in cardiac index, favorable modulation of the immune system, and improvement in survival. These actions are presumed to be of benefit in the treatment of sepsis or septic shock. However, there are few experimental data regarding the use of these solutions, and clinical studies are descriptive. The major impact of early administration of hypertonic solutions may be attenuation of tissue injury, sepsis, and septic shock. Early and aggressive fluid resuscitation with hypertonic solutions to clinical end-points should be investigated in patients with systemic inflammatory response syndrome, sepsis, and septic shock.