Clinical review: Hypertonic saline resuscitation in sepsis

European Society of Intensive Care Medicine clinical practice guideline on fluid therapy in adult critically ill patients. Part 1: the choice of resuscitation fluids

PURPOSE

This is the first of three parts of the clinical practice guideline from the European Society of Intensive Care Medicine (ESICM) on resuscitation fluids in adult critically ill patients. This part addresses fluid choice and the other two will separately address fluid amount and fluid removal.

METHODS

This guideline was formulated by an international panel of clinical experts and methodologists. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology was applied to evaluate the certainty of evidence and to move from evidence to decision.

RESULTS

For volume expansion, the guideline provides conditional recommendations for using crystalloids rather than albumin in critically ill patients in general (moderate certainty of evidence), in patients with sepsis (moderate certainty of evidence), in patients with acute respiratory failure (very low certainty of evidence) and in patients in the perioperative period and patients at risk for bleeding (very low certainty of evidence). There is a conditional recommendation for using isotonic saline rather than albumin in patients with traumatic brain injury (very low certainty of evidence). There is a conditional recommendation for using albumin rather than crystalloids in patients with cirrhosis (very low certainty of evidence). The guideline provides conditional recommendations for using balanced crystalloids rather than isotonic saline in critically ill patients in general (low certainty of evidence), in patients with sepsis (low certainty of evidence) and in patients with kidney injury (very low certainty of evidence). There is a conditional recommendation for using isotonic saline rather than balanced crystalloids in patients with traumatic brain injury (very low certainty of evidence). There is a conditional recommendation for using isotonic crystalloids rather than small-volume hypertonic crystalloids in critically ill patients in general (very low certainty of evidence).

CONCLUSIONS

This guideline provides eleven recommendations to inform clinicians on resuscitation fluid choice in critically ill patients.

Hyperosmolar Therapy in Elderly Neurosurgical Patients: Comparison of the Effect of Mannitol (20%) and Hypertonic Saline (3%) on Advanced Cardiovascular Parameters Using Transesophageal Echocardiography: A Preliminary Randomized Controlled Trial

OBJECTIVE

Osmotherapeutic agents increase the intravascular volume by withdrawing water from the brain followed by relative hypovolemia due to diuresis leading to significant changes in systemic hemodynamics which might have adverse consequences in the elderly. We studied the effect of mannitol (20%) and hypertonic saline (HTS) (3%) on left ventricular outflow tract velocity time integral (LVOT-VTI) and cardiac output (CO) in elderly patients undergoing supratentorial neurosurgical procedures using transesophageal echocardiography.

METHODS

We recruited 28 patients aged above 65 years undergoing supratentorial craniotomy who received equiosmolar solutions of 5.35 ml/kg of 3% HTS (group HS, n = 14) or 5 ml/kg of 20% mannitol (group M, n = 14). LVOT-VTI was recorded at baseline, 15, 30, 45, 60, and 90 minutes postinfusion and CO was derived. We also recorded heart rate, blood pressure, fluid balance, brain relaxation, vasopressor use, complications, and neurological outcome.

RESULTS

We found a significant decrease in LVOT-VTI at 45, and 60 minutes in group M as compared to group HS [mean (standard deviation), 16.76 (1.81) vs. 20.78 (1.87), P < 0.001, 17.4 (2.38) vs. 19.16 (2), P = 0.044, respectively]. We also found a corresponding significant fall in CO [3863.16 (845.87) vs. 4745.59 (1209.33) ml/minute, P = 0.034] and systolic blood pressure (P = 0.039), at 45 minutes in group M. Urine output was higher in group M (P < 0.001). All other parameters were comparable.

CONCLUSIONS

HTS appears to be associated with better systemic hemodynamics (LVOT-VTI, CO) while providing equivalent brain relaxation as mannitol in elderly patients. A future larger study is required to confirm our preliminary findings.

Intravenous fluid therapy in sepsis

Sepsis is the dysregulated immune response to severe infection that is common and lethal among critically ill patients. Fluid administration is a common treatment for hypotension and shock in early sepsis. Fluid therapy can also cause edema and organ dysfunction. Research on the best treatment strategies for sepsis has provided insights on the optimal timing, dose, and type of fluid to treat patients with sepsis. Initial research on early goal-directed therapy for sepsis included an initial bolus of 30 ml/kg of fluid, but more recent research has supported use of smaller volumes. After initial fluid resuscitation, minimizing additional fluid administration may be beneficial, but no single measure has been established as the best method to guide ongoing fluid management in sepsis. Dynamic measures of "fluid responsiveness" can predict which patients will experience an increase in cardiac output from a fluid bolus. Use of such a measure in clinical care remains limited by applicability to patient populations and uncertainty regarding the effect on clinical outcomes. Recent research informs the effect of fluid composition on outcomes for patients with sepsis. Current data support the use of balanced crystalloids, rather than saline, and the use of crystalloids, rather than semisynthetic colloids. The role for albumin administration in sepsis remains uncertain. Future research should focus on determining the optimal volume of fluid during sepsis resuscitation, the effectiveness of measures of "fluid responsiveness" in improving outcomes, the optimal composition of crystalloid solutions, the role of albumin, and the effects of "deresuscitation" after septic shock.

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.

Resuscitation fluids

PURPOSE OF REVIEW

Intravenous fluid administration is a fundamental therapy in critical care, yet key questions remain unanswered regarding optimal fluid composition and dose. This review evaluates recent evidence regarding the effects of fluid resuscitation on pathophysiology, organ function, and clinical outcomes for critically ill patients.

RECENT FINDINGS

Recent findings suggest that intravenous fluid composition affects risk of kidney injury and death for critically ill adults. Generally, the risk of kidney injury and death appears to be greater with semisynthetic colloids compared with crystalloids, and with 0.9% sodium chloride compared with balanced crystalloids. Whether a liberal, restrictive, or hemodynamic responsiveness-guided approach to fluid dosing improves outcomes during sepsis or major surgery remains uncertain.

SUMMARY

As evidence on fluid resuscitation evolves, a reasonable approach would be to use primarily balanced crystalloids, consider 2-3 l for initial fluid resuscitation of hypovolemic or distributive shock, and use measures of anticipated hemodynamic response to guide further fluid administration.

The Harmful Effects of Hypertonic Sodium Lactate Administration in Hyperdynamic Septic Shock

Hypertonic sodium lactate (HTL) expands intravascular volume and may provide an alternative substrate for cellular metabolism in sepsis. We compared the effects of HTL, hypertonic saline (HTS), 0.9% ("normal") saline (NS) and Ringer's lactate (RL) on hemodynamics, sublingual and renal microcirculation, renal, mesenteric and brain perfusion, renal and cerebral metabolism, and survival in anesthetized, mechanically ventilated, adult female sheep. Animals (7 in each group) were randomized to receive a bolus (over 15-min) of 3 mL/kg 0.5 M HTL, 3 mL/kg 3% HTS, 10.8 mL/kg NS, or 10.8 mL/kg RL at 2, 6, and 10 h after induction of fecal peritonitis, followed by 2-h infusions of 1 mL/kg/h (HTL/HTS groups) or 3.6 mL/kg/h (NS/RL groups). Animals also received RL and hydroxyethyl starch (ratio 1:1) titrated to maintain pulmonary artery occlusion pressure at baseline levels throughout the experiment. Animals were observed until their spontaneous death. Fluid balance was lower in the HTL and HTS groups than in the other groups from 4 h. Hemodynamic variables were similar among groups during the first 12 h, but thereafter the HTL group had more pronounced decreases in blood pressure and cardiac function. Sublingual and renal microcirculatory abnormalities occurred earlier in the HTL group. Kidney and brain perfusion decreased more rapidly in the HTL group. Median survival times were significantly shorter in the HTL (17 h) and NS (16 h) groups than in the HTS (22 h) or RL (20 h) groups (P = 0.0029). In conclusion, in an ovine model of septic shock, administration of HTL was associated with earlier onset impaired tissue perfusion and shorter survival time. These observations raise concerns about use of HTL in septic shock.

Choice of Fluid Therapy in the Initial Management of Sepsis, Severe Sepsis, and Septic Shock

Sepsis results in disruption of the endothelial glycocalyx layer and damage to the microvasculature, resulting in interstitial accumulation of fluid and subsequently edema. Fluid resuscitation is a mainstay in the initial treatment of sepsis, but the choice of fluid is unclear. The ideal resuscitative fluid is one that restores intravascular volume while minimizing edema; unfortunately, edema and edema-related complications are common consequences of current resuscitation strategies. Crystalloids are recommended as first-line therapy, but the type of crystalloid is not specified. There is increasing evidence that normal saline is associated with increased mortality and kidney injury; balanced crystalloids may be a safer alternative. Albumin is similar to crystalloids in terms of outcomes in the septic population but is costlier. Hydroxyethyl starches appear to increase mortality and kidney injury in the critically ill and are no longer indicated in these patients. In the trauma population, the shift to plasma-based resuscitation with decreased use of crystalloid and colloid in the treatment of hemorrhagic shock has led to decreased inflammatory and edema-mediated complications. Studies are needed to determine if these benefits also occur with a similar resuscitation strategy in the setting of sepsis.

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.

Fluids for Prevention and Management of Acute Kidney Injury

Fluids are the only known method of attenuating renal injury. Furthermore, whether for hydration, resuscitation or renal replacement therapy, fluid prescriptions must be tailored to the fluid and electrolyte, cardiovascular status and residual renal function of the patient. Different fluids have significantly different effects both on volume expansion as well as on the electrolyte and acid-base balance; while controversial, different fluids may even influence renal function differently. This systematic review focuses on fluids for prevention and management of acute kidney injury. We have reviewed the available evidence and have made recommendations for clinical practice and future studies.

The influence of acute elevations in plasma osmolality and serum sodium on sympathetic outflow and blood pressure responses to exercise

Elevated plasma osmolality (pOsm) has been shown to increase resting sympathetic nerve activity in animals and humans. The present study tested the hypothesis that increases in pOsm and serum sodium (sNa⁺) concentration would exaggerate muscle sympathetic nerve activity (MSNA) and blood pressure (BP) responses to handgrip (HG) exercise and postexercise ischemia (PEI). BP and MSNA were measured during HG followed by PEI before and after a 23-min hypertonic saline infusion (HSI-3% NaCl). Eighteen participants (age 23 ± 1 yr; BMI 24 ± 1 kg/m²) completed the protocol; pOsm and sNa⁺ increased from pre- to post-HSI (285 ± 1 to 291 ± 1 mosmol/kg H₂O; 138.2 ± 0.3 to 141.3 ± 0.4 mM; P < 0.05 for both). Resting mean BP (90 ± 2 vs. 92 ± 1 mmHg) and MSNA (11 ± 2 vs. 15 ± 2 bursts/min) were increased pre- to post-HSI ( P < 0.05 for both). Mean BP responses to HG (106 ± 2 vs. 111 ± 2 mmHg, P < 0.05) and PEI (102 ± 2 vs. 107 ± 2 mmHg, P < 0.05) were higher post-HSI. Similarly, MSNA during HG (20 ± 2 vs. 29 ± 2 bursts/min, P < 0.05) and PEI (19 ± 2 vs. 24 ± 3 bursts/min, P < 0.05) were greater post-HSI. In addition, the change in MSNA was greater post-HSI during HG (Δ9 ± 2 vs. Δ13 ± 3 bursts/min, P < 0.05). A second set of participants ( n = 13, age 23 ± 1 yr; BMI 24 ± 1 kg/m²) completed a time control (TC) protocol consisting of quiet rest instead of an infusion. The TC condition yielded no change in resting sNa⁺, pOsm, mean BP, or MSNA (all P > 0.05); responses to HG and PEI were not different pre- to post-quiet rest ( P > 0.05). In summary, acutely increasing pOsm and sNa⁺ exaggerates BP and MSNA responses during HG exercise and PEI. NEW & NOTEWORTHY Elevated plasma osmolality has been shown to increase resting sympathetic activity and blood pressure. This study provides evidence that acute elevations in plasma osmolality and serum sodium exaggerated muscle sympathetic nerve activity and blood pressure responses during exercise pressor reflex activation in healthy young adults.

Hypertonic Saline in the Treatment of Hemorrhagic Shock

Context

The present review discusses different studies about the treatment of hemorrhagic shock (HS) with hypertonic saline (HTS).

Evidence acquisition

We have searched the title in the most popular databases containing recent meta-analysis or randomized clinical trials (RCTs).

Results

We introduce the hemodynamic effects and mechanisms of action of HTS in HS. Evidence in this field shows controversial results. There are some data supporting the potential benefits of HTS infusion in HS. The goal of research in this field is to identify the best therapy in HS with the least mortality.

Conclusion

Our conclusion shows that although HTS can decrease inflammatory response during HS, it can attenuate hypercoagulability and cause complications. There are no data supporting less mortality while treatment with HTS versus other fluids in HS.

Management of Congestion and Diuretic Resistance in Heart Failure

We present the case of a patient with heart failure and severe congestion who was responding poorly to diuretic therapy. We discuss the key problems concerning the pathophysiology and bedside therapeutic approach to congestion and fluid overload in this clinical setting, and we give practical suggestions to overcome congestion, especially in the setting of diuretic resistance and worsening renal function. We conclude that the application of key pharmacokinetic and pharmacodynamic principles of diuretic therapy, along with in-depth knowledge of the pathophysiology of heart failure, still represent the cornerstones for a correct approach to decongestive therapy in these patients.

Hypertonic Saline (NaCl 7.5%) Reduces LPS-Induced Acute Lung Injury in Rats

Acute respiratory distress syndrome (ARDS) is the most severe lung inflammatory manifestation and has no effective therapy nowadays. Sepsis is one of the main illnesses among ARDS causes. The use of fluid resuscitation is an important treatment for sepsis, but positive fluid balance may induce pulmonary injury. As an alternative, fluid resuscitation with hypertonic saline ((HS) NaCl 7.5%) has been described as a promising therapeutical agent in sepsis-induced ARDS by the diminished amount of fluid necessary. Thus, we evaluated the effect of hypertonic saline in the treatment of LPS-induced ARDS. We found that hypertonic saline (NaCl 7.5%) treatment in rat model of LPS-induced ARDS avoided pulmonary function worsening and inhibited type I collagen deposition. In addition, hypertonic saline prevented pulmonary injury by decreasing metalloproteinase 9 (MMP-9) activity in tissue. Focal adhesion kinase (FAK) activation was reduced in HS group as well as neutrophil infiltration, NOS2 expression and NO content. Our study shows that fluid resuscitation with hypertonic saline decreases the progression of LPS-induced ARDS due to inhibition of pulmonary remodeling that is observed when regular saline is used.

Pretreatment with endothelium-derived nitric oxide synthesis modulators on gastrointestinal microcirculation during NOTES: an experimental study

BACKGROUND AND STUDY AIMS

On-demand endoscopic insufflation during natural orifice transluminal endoscopic surgery (NOTES) adversely affects microcirculatory blood flow (MBF), even with low mean intra-abdominal pressure, suggesting that shear stress caused by time-varying flow fluctuations has a great impact on microcirculation. As shear stress is inversely related to vascular diameter, nitric oxide (NO) production acts as a brake to vasoconstriction.

OBJECTIVE

To assess whether pretreatment by NO synthesis modulators protects gastrointestinal MBF during transgastric peritoneoscopy.

METHODS

Fourteen pigs submitted to cholecystectomy by endoscope CO₂ insufflation for 60 min were randomized into 2 groups: (1) 150 mg/kg of N-acetyl cysteine (NAC, n = 7) and (2) 4 ml/kg of hypertonic saline 7.5 % (HS, n = 7), and compared to a non-treated NOTES group (n = 7). Five animals made up a sham group. Colored microspheres were used to assess changes in MBF.

RESULTS

The average level of intra-abdominal pressure was similar in all groups (9 mmHg). In NOTES group microcirculation decrease compared with baseline was greater in renal cortex, mesocolon, and mesentery (41, 42, 44 %, respectively, p < 0.01) than in renal medulla, colon, and small bowel (29, 32, 34, respectively, p < 0.05). NAC avoided the peritoneoscopy effect on renal medulla and cortex (4 and 14 % decrease, respectively) and reduced the impact on colon and small bowel (20 % decrease). HS eliminated MBF changes in colon and small bowel (14 % decrease) and modulated MBF in renal medulla and cortex (19 % decrease). Neither treatment influenced mesentery MBF decrease.

CONCLUSIONS

Both pretreatments can effectively attenuate peritoneoscopy-induced deleterious effects on gastrointestinal MBF.

Acute-Phase Deaths from Murine Polymicrobial Sepsis Are Characterized by Innate Immune Suppression Rather Than Exhaustion

Sepsis, a leading cause of death in the United States, has poorly understood mechanisms of mortality. To address this, our model of cecal ligation and puncture (CLP) induced sepsis stratifies mice as predicted to Live (Live-P) or Die (Die-P) based on plasma IL-6. Six hours post-CLP, both Live-P and Die-P groups have equivalent peritoneal bacterial colony forming units and recruitment of phagocytes. By 24 h, however, Die-P mice have increased bacterial burden, despite increased neutrophil recruitment, suggesting Die-P phagocytes have impaired bacterial killing. Peritoneal cells were used to study multiple bactericidal processes: bacterial killing, reactive oxygen species (ROS) generation, and phagocytosis. Total phagocytosis and intraphagosomal processes were determined with triple-labeled Escherichia coli, covalently labeled with ROS- and pH-sensitive probes, and an ROS/pH-insensitive probe for normalization. Although similar proportions of Live-P and Die-P phagocytes responded to exogenous stimuli, Die-P phagocytes showed marked deficits in all parameters measured, thus suggesting immunosuppression rather than exhaustion. This contradicts the prevailing sepsis paradigm that acute-phase sepsis deaths (<5 d) result from excessive inflammation, whereas chronic-phase deaths (>5 d) are characterized by insufficient inflammation and immunosuppression. These data suggest that suppression of cellular innate immunity in sepsis occurs within the first 6 h.

When sepsis affects the heart: A case report and literature review

A 59-year-old nursing home patient with Down syndrome was brought to the internal medicine department of our hospital due to fever, cough without expectorate, and dyspnea. A thoracic computed tomography revealed the presence of bilateral basal parenchymal opacities. Her condition deteriorated after admission and troponin reached a peak serum concentration of 16.9 ng/mL. The patient was in cardiogenic shock. In addition to fluid resuscitation, vaso-active amine infusion was administered to achieve hemodynamic stabilization. The differential diagnosis investigated possible pulmonary embolism, myocardial infarction, and myocarditis. Furthermore, a second transthoracic echocardiogram suggested Tako-Tsubo syndrome. This is a septic patient. The purpose of this manuscript is to review studies which formerly examined the possible association between high levels of troponin and mortality to see if it can be considered a positive predictive factor of fatal prognosis as the case of thrombocytopenia, already a positive independent predictive factor of multiple organ failure syndrome, and generally to characterize risk profile in a septic patient.

Critical role of aquaporins in interleukin 1β (IL-1β)-induced inflammation

Rapid changes in cell volume characterize macrophage activation, but the role of water channels in inflammation remains unclear. We show here that, in vitro, aquaporin (AQP) blockade or deficiency results in reduced IL-1β release by macrophages activated with a variety of NLRP3 activators. Inhibition of AQP specifically during the regulatory volume decrease process is sufficient to limit IL-1β release by macrophages through the NLRP3 inflammasome axis. The immune-related activity of AQP was confirmed in vivo in a model of acute lung inflammation induced by crystals. AQP1 deficiency is associated with a marked reduction of both lung IL-1β release and neutrophilic inflammation. We conclude that AQP-mediated water transport in macrophages constitutes a general danger signal required for NLRP3-related inflammation. Our findings reveal a new function of AQP in the inflammatory process and suggest a novel therapeutic target for anti-inflammatory therapy.

Hypertonic saline solution drives neutrophil from bystander organ to infectious site in polymicrobial sepsis: a cecal ligation and puncture model

The effects of hypertonic saline solution (HSS) have been shown in several animal models of ischemia and shock. Literature has shown potential benefits of HSS modulating inflammatory response after sepsis in an animal model. We studied the HSS effects in sepsis through cecal ligation and puncture (CLP) in Balb-C mice. Groups studied: 1- CLP without treatment (CLP-C); 2- CLP treated with normal saline solution NaCl 0.9% – 34 ml/Kg (CLP-S); 3- CLP treated with HSS NaCl 7.5% – 4 ml/Kg (CLP-H); and 4- group (Basal) without no CLP or treatment. Volume infusion was always applied 30 min after CLP. Lung and peritoneal lavage were harvested after 6h and 24h of CLP to analyze cytokines amount, oxide nitric, lipid peroxidation and neutrophil infiltration. Neutrophil infiltration, ICAM-1, CXCR-2, and CXCL-1 in lung were reduced by HSS (CLP-H) compared to CLP-C or CLP-S. Neutrophil in peritoneal lavage was increased in 24h with HSS (CLP-H) compared to CLP and CLP-S. Peritoneal CXCR-2 was increased in CLP-C and CLP-S but presented a lower increase with HSS (CLP-H) after 6 hours. GRK-2 presented difference among the groups at 24 h, showing a profile similar to neutrophil infiltration. Pro-inflammatory cytokines (TNF-α and IL-6) were reduced by HSS treatment; CLP-S increased TNF-α. IL-10 was increased in lung tissue by the HSS treatment. The oxidative stress (TBARS and nitric oxide biochemistry markers) was reduced with HSS. Animal survival was 33.3% in CLP-C group, 46.6% in CLP-S group and 60% in the CLP-H group after the sixth day. The HSS protects the animal against sepsis. Our results suggest that the volume replacement modulate pro and anti-inflammatory mediators of an inflammatory response, but HSS presented a more effective and potent effect.

Fluid management in cardiac surgery: colloid or crystalloid?

The crystalloid-colloid debate has raged for decades, with the publication of many meta-analyses, yet no consensus. There are important differences between colloids and crystalloids, and these differences have direct relevance for cardiac surgical patients. Rather than asking crystalloid or colloid, we believe better questions to ask are (1) High or low chloride content? and (2) Synthetic or natural colloid? In this paper we review the published literature regarding fluid therapy in cardiac surgery and explain the background to these two important and unanswered questions.

New and future resuscitation fluids for trauma patients using hemoglobin and hypertonic saline

Hemoglobin-based oxygen carriers (HBOC) and hypertonic saline solutions (HSS) are used for resuscitation of trauma patients with hemorrhagic shock. In this review, the clinical application, dosing, administration, and side effects of these solutions are discussed. Although HBOC and HSS are not ideal resuscitation fluids, until rapidly thawed universal donor frozen blood and blood component therapy becomes widely available in North America, these fluids should to be considered immediately after injury and throughout the spectrum of care for patients with hemorrhagic shock, until blood and blood components become available.

Comparison of hypertonic saline versus normal saline on cytokine profile during CABG

Background and the purpose of the study

Blood contact with artificial surfaces of the extracorporeal circuit and ischemia-reperfusion injury in CABG with CPB, may lead to a systemic inflammatory response. Hypertonic saline have been recently investigated as a fluid in order to decrease inflammatory response and cytokines generation in patients undergo cardiac operations. Our purpose is to study the prophylactic effect of HS 5% infusion versus NS on serum IL-6 as an inflammatory & IL-10 as an anti-inflammatory biomarker in CABG patients.

Methods

The present study is a randomized double-blinded clinical trial. 40 patients undergoing CABG were randomized to receive HS 5% or NS before operation. Blood samples were obtained after receiving HS or NS, just before operation, 24 and 48 hours post-operatively. Plasma levels of IL-6 and IL-10 were measured by ELISA.

Results and major conclusion

Patients received HS had lower levels of IL-6 and higher level of IL-10 compared with NS group, however these differences were not statistically significant. Results of this study suggest that pre-treatment with small volume hypertonic saline 5% may have beneficial effects on inflammatory response following CABG operation.

Cell volume regulation modulates NLRP3 inflammasome activation

Cell volume regulation is a primitive response to alterations in environmental osmolarity. The NLRP3 inflammasome is a multiprotein complex that senses pathogen- and danger-associated signals. Here, we report that, from fish to mammals, the basic mechanisms of cell swelling and regulatory volume decrease (RVD) are sensed via the NLRP3 inflammasome. We found that a decrease in extracellular osmolarity induced a K(+)-dependent conformational change of the preassembled NLRP3-inactive inflammasome during cell swelling, followed by activation of the NLRP3 inflammasome and caspase-1, which was controlled by transient receptor potential channels during RVD. Both mechanisms were necessary for interleukin-1β processing. Increased extracellular osmolarity prevented caspase-1 activation by different known NLRP3 activators. Collectively, our data identify cell volume regulation as a basic conserved homeostatic mechanism associated with the formation of the NLRP3 inflammasome and reveal a mechanism for NLRP3 inflammasome activation.

Hypertonic fluid administration in patients with septic shock: a prospective randomized controlled pilot study

We assessed the short-term effects of hypertonic fluid versus isotonic fluid administration in patients with septic shock. This was a double-blind, prospective randomized controlled trial in a 15-bed intensive care unit. Twenty-four patients with septic shock were randomized to receive 250 mL 7.2% NaCl/6% hydroxyethyl starch (HT group) or 500 mL 6% hydroxyethyl starch (IT group). Hemodynamic measurements included mean arterial blood pressure (MAP), central venous pressure, stroke volume index, stroke volume variation, intrathoracic blood volume index, gastric tonometry, and sublingual microcirculatory flow as assessed by sidestream dark field imaging. Systolic tissue Doppler imaging velocities of the medial mitral annulus were measured using echocardiography to assess left ventricular contractility. Log transformation of the ratio MAP divided by the norepinephrine infusion rate (log MAP/NE) quantified the combined effect on both parameters. Compared with the IT group, hypertonic solution treatment resulted in an improvement in log MAP/NE (P = 0.008), as well as an increase in systolic tissue Doppler imaging velocities (P = 0.03) and stroke volume index (P = 0.017). No differences between the groups were found for preload parameters (central venous pressure, stroke volume variation, intrathoracic blood volume index) or for afterload parameters (systemic vascular resistance index, MAP). Hypertonic solution treatment decreased the need for ongoing fluid resuscitation (P = 0.046). No differences between groups were observed regarding tonometry or the sublingual microvascular variables. In patients with septic shock, hypertonic fluid administration did not promote gastrointestinal mucosal perfusion or sublingual microcirculatory blood flow in comparison to isotonic fluid. Independent of changes in preload or afterload, hypertonic fluid administration improved the cardiac contractility and vascular tone compared with isotonic fluid. The need for ongoing fluid resuscitation was also reduced.

Small-volume hypertonic saline/pentastarch improves ileal mucosal microcirculation in experimental peritonitis

We compared the effects of hypertonic saline 7.2%/6% hydroxyethyl starch (HSS-HES) and isotonic saline 0.9%/6% hydroxyethyl starch (ISS-HES) on ileal microcirculatory blood flow (MBF) at the initial phase of septic shock. Pigs were anesthetized and mechanically ventilated. Catheters were inserted into right atrium, pulmonary artery, carotid artery, and portal vein for hemodynamic measurements and for blood sampling. Ileal mucosal and muscularis MBF was continuously measured by laser Doppler flowmetry (LDF). Septic shock was obtained 240 min after induction of fecal peritonitis; then animals were randomized to receive 10 mL.kg(-1) during 10 min of either HSS-HES or ISS-HES. Systemic and microcirculatory blood flow as well as systemic metabolism were assessed. Fecal peritonitis promoted a hypodynamic septic shock, with significant reduction of mean arterial pressure (MAP) and cardiac index (CI). Ileal mucosal MBF (-34%) and ileal muscularis MBF (-54%) significantly diminished from baseline. Contrary to ISS-HES group, mucosal MBF significantly augmented after HSS-HES (+192% at min 150 post-shock) despite low blood pressure. There was weak correlation with CI (r(2)= 0.2, P=0.01) . Muscularis MBF didn't change. HSS-HES-treated animals had a significantly higher osmolarity and sodium concentration than ISS-HES group. Other variables did not change. Small-volume resuscitation with HSS-HES, but not ISS-HES, improved ileal microcirculatory impairment in experimental peritonitis model of septic shock even when MAP was low. This beneficial microcirculatory effect could be valuable in the management of early severe sepsis.

Influence of preoperative 7.5% hypertonic saline on neutrophil activation after reamed intramedullary nailing of femur shaft fractures: a prospective randomized pilot study

OBJECTIVES

Femoral reaming and intramedullary nailing (IMN) primes polymorphonuclear leukocytes (PMNL) and thereby increases the posttraumatic systemic inflammatory response. Resuscitation with hypertonic saline (HTS) attenuates PMNL activation after trauma-hemorrhage. We hypothesized that preoperative administration of 7.5% HTS attenuates PMNL priming after IMN of unilateral femur shaft fractures compared with 0.9% normal saline.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Level I trauma center.

PATIENTS

Twenty patients between 18 and 80 years of age with an Injury Severity Score less than 25 and a unilateral femur shaft fracture amenable to IMN fixation within 24 hours after injury.

INTERVENTION

Patients were allocated to equally sized HTS or normal saline treatment groups (n = 10) before surgery. Solutions were administered in a blinded bag as a single bolus of 4 mL/kg body weight immediately before surgery. Whole blood samples were collected directly before saline application (t0) and at 6, 12, and 24 hours after surgery.

MAIN OUTCOME MEASUREMENTS

PMNL surface expression of CD11b and CD62L, as determined by flow cytometry analysis.

RESULTS

Demographic characteristics of both treatment groups were comparable. Baseline expression of CD11b and CD62L cell markers was in a similar range in the two cohorts. The expression levels of CD11b were comparable between the two groups throughout the observation time, whereas CD62L levels were significantly higher in the HTS group at 6 and 24 hours after surgery.

CONCLUSION AND SIGNIFICANCE

Preoperative infusion of HTS appears to exert an anti-inflammatory effect by attenuating the extent of postoperative PMNL activation after reamed IMN for femoral shaft fractures.

The effects of hypertonic fluid administration on the gene expression of inflammatory mediators in circulating leucocytes in patients with septic shock: a preliminary study

Objective

This study was designed to investigate the effect of hypertonic fluid administration on inflammatory mediator gene expression in patients with septic shock.

Design and setting

Prospective, randomized, controlled, double-blind clinical study in a 15-bed mixed intensive care unit in a tertiary referral teaching hospital.

Interventions

Twenty-four patients, who met standard criteria for septic shock, were randomized to receive a bolus of hypertonic fluid (HT, 250 ml 6% HES/7.2% NaCl) or isotonic fluid (IT, 500 ml 6% HES/0.9% NaCl) administered over 15 minutes. Randomization and study fluid administration was within 24 hours of ICU admission for all patients. This trial is registered with ANZCTR.org.au as ACTRN12607000259448.

Results

Blood samples were taken immediately before and 4, 8, 12, and 24 hours after fluid administration. Real-time reverse transcriptase polymerase chain reaction (RT rtPCR) was used to quantify mRNA expression of different inflammatory mediators in peripheral leukocytes. In the HT group, compared with the IT group, levels of gene expression of MMP9 and L-selectin were significantly suppressed (p = 0.0002 and p = 0.007, respectively), and CD11b gene expression tended to be elevated (p = NS). No differences were found in the other mediators examined.

Conclusions

In septic shock patients, hypertonic fluid administration compared with isotonic fluid may modulate expression of genes that are implicated in leukocyte-endothelial interaction and capillary leakage.

The study was performed at the Intensive Care Department, Waikato Hospital, and at the Molecular Genetics Laboratory, University of Waikato, Hamilton, New Zealand.

Trial registration

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12607000259448

Short-term effects of hypertonic saline solution in acute heart failure and long-term effects of a moderate sodium restriction in patients with compensated heart failure with New York Heart Association class III (Class C) (SMAC-HF Study)

INTRODUCTION

Hypertonic saline solution (HSS) and a moderate Na restriction plus high furosemide dose showed beneficial effects in compensated heart failure (HF), in short and long terms. The study was aimed to verify the effects of this combination on hospitalization time, readmissions and mortality in patients in New York Heart Association (NYHA) class III.

METHOD

Chronic ischemic or nonischemic cardiomyopathy uncompensated patients with HF in NYHA III functional class with ejection fraction <40%, serum creatinine <2.5 mg/dL, blood urea nitrogen <60 mg/dL and reduced urinary volume were single-blind randomized in 2 groups: the first group received a 30-minute intravenous infusion of furosemide (250 mg) plus HSS (150 mL) twice daily and a moderate Na restriction (120 mmol); the second group received furosemide intravenous bolus (250 mg) twice a day, without HSS and a low Na diet (80 mmol); both groups received a fluid intake of 1000 mL/d. After discharge, the HSS group continued with 120 mmol Na/d; the second group continued with 80 mmol Na/d.

RESULTS

A total of 1771 patients (881 HSS group and 890 without HSS group) met inclusion criteria: the first group (881 patients), compared with the second (890 patients), showed an increase in diuresis and serum Na levels, a reduction in hospitalization time (3.5 + 1 versus 5.5 + 1 days, P < 0.0001) and, during follow-up (57 + 15 months), a lower rate in readmissions (18.5% versus 34.2%, P < 0.0001) and mortality (12.9% versus 23.8%, P < 0.0001); the second group also showed a significant increase in blood urea nitrogen and serum creatinine.

CONCLUSION

This study suggests that in-hospital HSS administration, combined with moderate Na restriction, reduces hospitalization time and that a moderate sodium diet restriction determines long-term benefit in patients with NYHA class III HF.

Hypertonic versus normal saline as initial fluid bolus in pediatric septic shock

OBJECTIVE

To compare the efficacy of 3% saline and 0.9% saline infusion as initial resuscitative fluid therapy in children with septic shock.

METHODS

Sixty children between 2 to 12 years of age with septic shock were randomized to receive normal saline or 3% saline as initial resuscitative fluid. Fluid resuscitation was done with 0.9% saline in boluses of 20 ml/kg, each bolus over a duration of 15 min with a maximum of 2 boluses. Fluid resuscitation with 3% saline was given as a single bolus of 15 ml/kg over 30 min. After initial fluid bolus completion, if hemodynamic stability was not achieved then further fluid boluses of 0.9% saline were given in volumes of 5-10 ml/kg guided by CVP.

RESULTS

There were 30 patients in both the groups. Both the groups were identical with respect to age, gender, primary diagnosis, laboratory parameters, initial hemodynamic parameters and PRISM score at time of admission. The amount of total fluid bolus required for resuscitation was approximately half in the group who received 3% saline as compared to the group who received 0.9% saline. The use of vasopressor drugs, shock reversal time, ICU stay and mortality rate were similar in both the groups. No adverse effects related to fluid therapy were observed in any of the groups.

CONCLUSIONS

Both normal saline and hypertonic saline were equally effective as resuscitation fluid with respect to restoration of hemodynamic stability, average duration of ICU stay and mortality. Hypertonic saline appears to be a promising fluid for resuscitation of septic shock.

Impact of hypertonic saline on the release of selected cytokines after stimulation with LPS or peptidoglycan in ex vivo whole blood from healthy humans

The question of specific immunomodulating qualities of hypertonic saline (HTS) has not been settled. It has proven difficult to distinguish between immunomodulation directly attributable to HTS and influence because of favorable circulatory effects. The nature of immune activator may also play a role. In a whole-blood model, we have investigated these relations further, with special emphasize on osmolalities usually found after recommended dosing. Blood from 10 healthy donors was exposed to osmolalities ranging from 295 to 480 mOsm/kg and stimulated with the two clinically relevant stimulators peptidoglycan (1 µg/mL) or LPS (10 ng/mL) for 6 h at 37°C. Leukocyte response was evaluated by measuring selected cytokines in the supernatant. Moderate hyperosmolality alone boosted the release of CXCL8/IL-8. The peptidoglycan-stimulated synthesis of pivotal proinflammatory cytokines was inhibited in an osmolality-dependent way, but statistically significant only at osmolalities above those attained after routine use of HTS, i.e., 310 mOsm/kg or greater: IL-6 (P < 0.05 at 315 mOsm/kg), IL-1ß, and TNF-α (P < 0.05 at 335 mOsm/kg). Similar effects were seen for the chemokine CCL3 and the anti-inflammatory cytokine IL-10. In contrast, the effects in cells stimulated with LPS were either lower or absent. Thus, osmolalities usually found after clinical use of HTS only modestly influenced the selected immune parameters, regardless of stimulator.

Early fluid resuscitation

Solid evidence exists that fluid therapy must be started as a first-line treatment in all patients with septic shock as soon as hypotension is detected, with the goal of rapidly restoring tissue perfusion. Crystalloids or colloids can be used for initial fluid therapy, and albumin should be reserved for patients with patent or supposed hypoalbuminemia. Once fluid administration is started, its effect must be carefully monitored. In the early stages, appropriate monitoring should ensure that fluid resuscitation actually increases cardiac preload, mean arterial pressure, and tissue oxygenation. In later stages, monitoring should help to avoid fluid overload. For this purpose, the end-point of fluid therapy should not be the static values of preload indicators, but rather the disappearance of indicators of preload responsiveness. Finally, the risk of fluid overload must always be kept in mind, especially in case of lung injury.

Rubbing salt into wounds: hypertonic saline to assist with volume removal in heart failure

Traditionally accepted management strategies for patients with heart failure include sodium and fluid restriction, neurohormonal blockade, and the use of loop diuretics to achieve and maintain euvolemia. Despite continued advances in medical and device therapy, fluid management remains a significant problem in patients with the cardiorenal syndrome (manifested as diuretic resistance and worsening renal function with more aggressive attempts at volume removal). This article examines the counterintuitive use of hypertonic saline as a potential therapy to facilitate diuresis in patients with decompensated heart failure and diuretic resistance. Low-volume hypertonic saline administration offsets counterproductive neurohormonal upregulation, transiently improves hemodynamics, and promotes renal sodium excretion with accompanied net water loss and preservation of renal function. This "new" therapeutic tool should be explored further as an adjunct to current medical therapies in the management of patients with refractory volume overload.

Osmoregulation of vasopressin secretion is altered in the postacute phase of septic shock

OBJECTIVE

To determine whether septic shock patients have an abnormal reponse to increasing osmolarity.

DESIGN

Prospective interventional study.

SETTING

Intensive care unit at Raymond Poincaré and Etampes Hospitals.

PATIENTS

Normonatremic patients at > 72 hrs from septic shock onset.

INTERVENTION

Osmotic challenge consisting of infusing 500 mL of hypertonic saline solution (with cumulative amount of sodium not exceeding 24 g) over 120 mins.

MEASUREMENTS AND MAIN RESULTS

Plasma arginine vasopressin levels were measured 15 mins before the test and then four times every 30 mins. A slope of the relation between arginine vasopressin and plasma sodium levels of < 0.5 pg/mEq defined nonresponders. Among the 33 included patients, 17 (52%) were nonresponders. During osmotic challenge, variations throughout the test in plasma sodium levels, blood pressure, and central venous pressure were comparable between the two groups. Arginine vasopressin increased from 4.8 pg/mL [3.3-6.4 pg/mL] to 14.4 pg/mL [11.2-23.3 pg/mL] in responders but only from 2.8 pg/mL [2.3-4.0 pg/mL] to 4.0 pg/mL [3.1-5.3 pg/mL] in nonresponders (p < .0001). Responders had a higher plasma arginine vasopressin levels at baseline and a more severe hematosis alteration. Nonresponders had more frequently bacteremia and liver dysfunction, been referred from the ward and undergone surgery. Critical illness severity, hemodynamic alteration, hydroelectrolytic disturbances, treatment, and outcome did not differ between the two groups.

CONCLUSION

Osmoregulation is dramatically altered in half of patients with prolonged septic shock.

Hypertonic saline, mannitol and hydroxyethyl starch preconditioning of platelets obtained from septic patients attenuates CD40 ligand expression in vitro

BACKGROUND

Because platelet CD40 ligand (CD40L) expression plays an important role in inflammatory conditions, reduction of CD40L expression may be beneficial for patients with sepsis. Although hypertonic saline, mannitol, and hydroxyethyl starch (HES) solutions have been shown to modulate inflammatory responses, their effects on platelet CD40L expression are unclear. We assessed the effects of hypertonic saline, mannitol, and HES solutions on platelet CD40L expression.

METHODS

Platelet-rich plasma samples were obtained from septic patients and diluted to 1%, 2.5%, 5%, or 7.5% (vol/vol) with 7.5% saline, 3% saline, 0.9% saline, 20% mannitol, 10% HES (200/0.5), or Ringer's solution. Twenty-five samples were used per dilution. To determine platelet CD40L expression, platelet samples were stimulated with thrombin (0.1 U/mL), incubated with fluorochrome-conjugated platelet antibodies, and analyzed using flow cytometry.

RESULTS

Preconditioning of platelet-rich plasma with hypertonic saline, mannitol, and HES attenuated CD40L expression at dilution ratios of 5%, 1%, and 1%, respectively. The decreases were concentration dependent. The effects of mannitol and HES on CD40L expression were almost identical and were superior to those of 3% saline. In contrast, 0.9% saline and Ringer's solution had no effect on CD40L expression.

CONCLUSIONS

Our data show that resuscitation fluids, such as hypertonic saline, mannitol, and HES, inhibit agonist-induced CD40L expression on platelets. These resuscitation fluids may have an anti-inflammatory action when administered to septic patients.

Can hypertonic saline influence platelet P selectin expression and platelet-leukocyte aggregation?

OBJECTIVES

Part of platelet function involves aggregation and activation. Activation leads to platelet P selectin expression and platelet-leukocyte aggregation. Hypertonic saline inhibits platelet aggregation, although the effects of hypertonic saline on platelet activation are not known. We evaluated the effects of hypertonic saline on platelet activation as measured by platelet P selectin expression and platelet-leukocyte aggregation.

METHODS

Blood samples from healthy volunteers (n = 6) were treated in vitro with various solutions including 23.5%, 7.5%, 3%, and 0.9% saline; Ringer's solution; 5% dextrose in water; and 10% hydroxyethyl starch. Blood was diluted with each type of solution to 2.5%, 5%, 10%, 20%, and 30% (vol/vol) dilution. All blood samples were activated with adenosine diphosphate (20 micromol/L), stained with fluorochrome-conjugated antibodies, and analyzed by flow cytometry to measure platelet P selectin expression and platelet-leukocyte aggregation.

RESULTS

The 23.5% saline solution reduced P selectin expression at 20% and 30% dilutions and platelet-leukocyte aggregation at 10%, 20%, and 30% dilutions. The 7.5% solution saline had no effect on P selectin expression and significantly inhibited platelet-leukocyte aggregation only at 30% dilution. Other solutions had no effect on platelet P selectin expression or platelet-leukocyte aggregation.

CONCLUSIONS

Our data suggest that hypertonic saline does not affect platelet P selectin expression or platelet-leukocyte aggregation at therapeutic plasma concentrations but that an inhibitory effect occurs at supratherapeutic doses. Dilutions of other solutions caused the least disturbance of platelet activation.

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

Hypertonic saline has been in clinical use for many decades. Its osmotic and volume-expanding properties make it theoretically useful for a number of indications in critical care. This literature review evaluates the use of hypertonic saline in critical care. The putative mechanism of action is presented, followed by a narrative review of its clinical usefulness in critical care. The review was conducted using the Scottish Intercollegiate Guidelines Network method for the review of cohort studies, randomised-controlled trials and meta-analyses. The review focuses specifically on blood pressure restoration and outcome benefit in both haemorrhagic and non-haemorrhagic shock, and the management of raised intracranial pressure. Issues of clinical improvement and outcome benefit are addressed. Hypertonic saline solutions are effective for blood pressure restoration in haemorrhagic, but not other, types of shock. There is no survival benefit with the use of hypertonic saline solutions in shock. Hypertonic saline solutions are effective at reducing intracranial pressure in conditions causing acute intracranial hypertension. There is no survival or outcome benefit with the use of hypertonic saline solutions for raised intracranial pressure. Recommendations for clinical use and future directions of clinical research are presented.

Hypertonic saline reduces metalloproteinase expression in liver during pancreatitis

1. We recently demonstrated that hypertonic saline reduces inflammation and mortality in acute pancreatitis. The present study investigated the effects of hypertonic saline in metalloproteinase (MMP) regulation and pancreatitis-associated hepatic injury. 2. Wistar rats were divided into four groups: (i) control, not subjected to insult or treatment; (ii) no treatment (NT), induction of pancreatitis (retrograde infusion of 2.5% sodium taurocholate (1.0 mL/kg)), but no further treatment; (iii) normal saline (NS), induction of pancreatitis and treatment with normal saline (0.9% NaCl, 34 mL/kg, i.v. bolus, 1 h after the induction of pancreatitis); and (iv) hypertonic saline (HS), induction of pancreatitis and treatment with hypertonic saline (7.5% NaCl, 4 mL/kg administered over a period of 5 min, 1 h after the induction of pancreatitis). In all four groups, 4, 12 and 24 h after the induction of pancreatitis, liver tissue samples were assayed to determine levels of MMP-2, MMP-9, 47 kDa heat shock protein (HSP47) and collagen (Type I and III). 3. Compared with the control group, MMP-9 expression and activity was increased twofold in the NS and NT groups 4 and 12 h after the induction of pancreatitis, but remained at basal levels in the HS group. In contrast, MMP-2 expression was increased twofold 12 h after the induction of pancreatitis only in the NS group, whereas the expression of HSP47 was increased 4 h after the induction of pancreatitis in the NS and NT groups. Greater extracellular matrix remodelling occurred in the NS and NT groups compared with the HS group, probably as a result of the hepatic wound-healing response to repeated injury. However, the collagen content in hepatic tissue remained at basal levels in the HS group. 4. In conclusion, the results of the present study indicate that hypertonic saline is hepatoprotective and reduces hepatic remodelling, maintaining the integrity of the hepatic extracellular matrix during pancreatitis. Hypertonic saline-mediated regulation of MMP expression may have clinical relevance in pancreatitis-associated liver injury.

The use of hypertonic saline for fluid resuscitation in sepsis: a review

Early volume resuscitation of a patient with sepsis has been shown to reduce morbidity, mortality, and healthcare resource consumption. Hypertonic saline offers a theoretically viable option for volume resuscitation. This article reviews the current information available regarding fluid resuscitation in patients with sepsis, with emphasis on the use of hypertonic saline.

Cell volume regulation: physiology and pathophysiology

Cell volume perturbation initiates a wide array of intracellular signalling cascades, leading to protective and adaptive events and, in most cases, activation of volume-regulatory osmolyte transport, water loss, and hence restoration of cell volume and cellular function. Cell volume is challenged not only under physiological conditions, e.g. following accumulation of nutrients, during epithelial absorption/secretion processes, following hormonal/autocrine stimulation, and during induction of apoptosis, but also under pathophysiological conditions, e.g. hypoxia, ischaemia and hyponatremia/hypernatremia. On the other hand, it has recently become clear that an increase or reduction in cell volume can also serve as a specific signal in the regulation of physiological processes such as transepithelial transport, cell migration, proliferation and death. Although the mechanisms by which cell volume perturbations are sensed are still far from clear, significant progress has been made with respect to the nature of the sensors, transducers and effectors that convert a change in cell volume into a physiological response. In the present review, we summarize recent major developments in the field, and emphasize the relationship between cell volume regulation and organism physiology/pathophysiology.

Hyperglycemia may alter cytokine production and phagocytosis by means other than hyperosmotic stress

In the previous issue of Critical Care, Otto and colleagues used in vitro studies to explore the theory that immunomodulation, by correction of hyperglycemia, may be a contributing factor to the reported efficacy of intensive insulin therapy (IIT) in critically ill patients. They suggested that hyperglycemia via hyperosmolarity at supra-physiological levels potentiates the production of cytokines by peripheral blood mononuclear cells in response to lipopolysaccharide (LPS) stimulation and that it also reduces the responses of phagocytosis and oxidative burst in human granulocytes. The efficacy of IIT, they concluded, may be partially due to the correction of hyperosmolality. Other studies, however, have suggested that immunological responses to LPS in the presence of hyperglycemia are mediated by a mechanism other than hyperosmolality.

Hypertonic saline up-regulates A3 adenosine receptor expression of activated neutrophils and increases acute lung injury after sepsis

OBJECTIVE

Hypertonic saline resuscitation reduces tissue damage by inhibiting polymorphonuclear neutrophils. Hypertonic saline triggers polymorphonuclear neutrophils to release adenosine triphosphate that is converted to adenosine, inhibiting polymorphonuclear neutrophils through A2a adenosine receptors. Polymorphonuclear neutrophils also express A3 adenosine receptors that enhance polymorphonuclear neutrophil functions. Here we investigated whether A3 receptors may diminish the efficacy of hypertonic saline in a mouse model of acute lung injury.

DESIGN

Randomized animal study and laboratory investigation.

SETTING

University research laboratory.

INTERVENTIONS

The effect of A3 receptors on the efficacy of hypertonic saline resuscitation was assessed in A3 receptor knockout and wild-type mice. Animals were treated with hypertonic saline (7.5% NaCl, 4 mL/kg) before or after cecal ligation and puncture, and acute lung injury and mortality were determined. The effect of timing of hypertonic saline exposure on A3 receptor expression and degranulation was studied in vitro with isolated human polymorphonuclear neutrophils.

MEASUREMENTS AND MAIN RESULTS

Treatment of human polymorphonuclear neutrophils with hypertonic saline before stimulation with formyl methionyl-leucyl-phenylalanine inhibited A3 receptor expression and degranulation, whereas hypertonic saline-treatment after formyl methionyl-leucyl-phenylalanine-stimulation augmented A3 receptor expression and degranulation. Acute lung injury in wild-type mice treated with hypertonic saline after cecal ligation and puncture was significantly greater than in wild-type mice pretreated with hypertonic saline. This aggravating effect of delayed hypertonic saline-treatment was absent in A3 receptor knockout mice. Similarly, mortality in wild-type mice with delayed hypertonic saline-treatment was significantly higher (88%) than in animals treated with hypertonic saline before cecal ligation and puncture (50%). Mortality in A3 receptor knockout mice remained only 50% regardless of timing of hypertonic saline administration.

CONCLUSIONS

Polymorphonuclear neutrophil A3 receptors expression determines whether hypertonic saline resuscitation inhibits or aggravates polymorphonuclear neutrophil-induced acute lung injury. These findings suggest that A3 antagonists could improve the efficacy of hypertonic saline resuscitation by reducing side effects in patients whose polymorphonuclear neutrophils are activated before hypertonic saline treatment.