Infusion of hypertonic saline (7.5% NaCl) causes minor immunological changes in normovolaemic women

Influence of Suboptimal Hydration on the Immune Response

BACKGROUND

A healthy immune system is a subtle orchestration of the innate and adaptive immune systems that efficiently detect and process foreign antigens while tolerating the self. The influence of hypertonicity on the immune system is poorly understood [1-16].

SUMMARY

In vitro studies suggest that hypertonicity influences innate and adaptive immunity on several cellular and molecular levels. This influence tends to be pro-inflammatory, but not always. Other cofactors include the duration of exposure to hypertonicity (chronic versus acute), the location in the body, and the timing with priming of the immune system. Recent publications about high salt diet in vitro and in animal models of multiple sclerosis (MS) suggest an influence on the TH17 autoimmune pathway, that does not translate into the human disease in vivo. Key Messages: The influence of hypertonicity on the immune system is complex and depends on multiple factors, such as temporality with immune priming and length of exposure. Since findings in animal models did not always translate into human diseases, further studies are needed to specify the consequences of acute or chronic hypertonicity in healthy subjects or patients with autoimmune diseases such as MS. Further studies need to be conducted in animal models and in humans to better understand the influence of suboptimal hydration on the immune system and on autoimmune diseases, and address its clinical relevance.

Hypotheses about sub-optimal hydration in the weeks before coronavirus disease (COVID-19) as a risk factor for dying from COVID-19

To address urgent need for strategies to limit mortality from coronavirus disease 2019 (COVID-19), this review describes experimental, clinical and epidemiological evidence that suggests that chronic sub-optimal hydration in the weeks before infection might increase risk of COVID-19 mortality in multiple ways. Sub-optimal hydration is associated with key risk factors for COVID-19 mortality, including older age, male sex, race-ethnicity and chronic disease. Chronic hypertonicity, total body water deficit and/or hypovolemia cause multiple intracellular and/or physiologic adaptations that preferentially retain body water and favor positive total body water balance when challenged by infection. Via effects on serum/glucocorticoid-regulated kinase 1 (SGK1) signaling, aldosterone, tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), aquaporin 5 (AQP5) and/or Na⁺/K⁺-ATPase, chronic sub-optimal hydration in the weeks before exposure to COVID-19 may conceivably result in: greater abundance of angiotensin converting enzyme 2 (ACE2) receptors in the lung, which increases likelihood of COVID-19 infection, lung epithelial cells which are pre-set for exaggerated immune response, increased capacity for capillary leakage of fluid into the airway space, and/or reduced capacity for both passive and active transport of fluid out of the airways. The hypothesized hydration effects suggest hypotheses regarding strategies for COVID-19 risk reduction, such as public health recommendations to increase intake of drinking water, hydration screening alongside COVID-19 testing, and treatment tailored to the pre-infection hydration condition. Hydration may link risk factors and pathways in a unified mechanism for COVID-19 mortality. Attention to hydration holds potential to reduce COVID-19 mortality and disparities via at least 5 pathways simultaneously.

Hypertonic saline in critical illness - A systematic review

INTRODUCTION

The optimal approach to fluid management in critically ill patients is highly debated. Fluid resuscitation using hypertonic saline was used in the past for more than thirty years, but has recently disappeared from clinical practice. Here we provide an overview on the currently available literature on effects of hypertonic saline infusion for fluid resuscitation in the critically ill.

METHODS

Systematic analysis of reports of clinical trials comparing effects of hypertonic saline as resuscitation fluid to other available crystalloid solutions. A literature search of MEDLINE and the Cochrane Controlled Clinical trials register (CENTRAL) was conducted to identify suitable studies.

RESULTS

The applied search strategy produced 2284 potential publications. After eliminating doubles, 855 titles and abstracts were screened and 40 references retrieved for full text analysis. At total of 25 scientific studies meet the prespecified inclusion criteria for this study.

CONCLUSION

Fluid resuscitation using hypertonic saline results in volume expansion and less total infusion volume. This may be of interest in oedematous patients with intravascular volume depletion. When such strategies are employed, renal effects may differ markedly according to prior intravascular volume status. Hypertonic saline induced changes in serum osmolality and electrolytes return to baseline within a limited period in time. Sparse evidence indicates that resuscitation with hypertonic saline results in less perioperative complications, ICU days and mortality in selected patients. In conclusion, the use of hypertonic saline may have beneficial features in selected critically ill patients when carefully chosen. Further clinical studies assessing relevant clinical outcomes are warranted.

Hypertonic salt solution for peri-operative fluid management

BACKGROUND

Fluid excess may place people undergoing surgery at risk for various complications. Hypertonic salt solution (HS) maintains intravascular volume with less intravenous fluid than isotonic salt (IS) solutions, but may increase serum sodium. This review was published in 2010 and updated in 2016.

OBJECTIVES

To determine the benefits and harms of HS versus IS solutions administered for fluid resuscitation to people undergoing surgery.

SEARCH METHODS

In this updated review we have searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 4, 2016); MEDLINE (January 1966 to April 2016); EMBASE (January 1980 to April 2016); LILACS (January 1982 to April 2016) and CINAHL (January 1982 to April 2016) without language restrictions. We conducted the original search on April 30th, 2007, and reran it on April 8th, 2016.

SELECTION CRITERIA

We have included randomized clinical trials (RCTs) comparing HS to IS in people undergoing surgery, irrespective of blinding, language, and publication status.

DATA COLLECTION AND ANALYSIS

Two independent review authors read studies that met our selection criteria. We collected study information and data using a data collection sheet with predefined parameters. We have assessed the impact of HS administration on mortality, organ failure, fluid balance, serum sodium, serum osmolarity, diuresis and physiologic measures of cardiovascular function. We have pooled the data using the mean difference (MD) for continuous outcomes. We evaluated heterogeneity between studies by I² percentage. We consider studies with an I² of 0% to 30% to have no or little heterogeneity, 30% to 60% as having moderate heterogeneity, and more than 60% as having high heterogeneity. In studies with low heterogeneity we have used a fixed-effect model, and a random-effects model for studies with moderate to high heterogeneity.

MAIN RESULTS

We have included 18 studies with 1087 participants of whom 545 received HS compared to 542 who received IS. All participants were over 18 years of age and all trials excluded high-risk patients (ASA IV). All trials assessed haematological parameters peri-operatively and up to three days post-operatively.There were three (< 1%) deaths reported in the IS group and four (< 1%) in the HS group, as assessed at 90 days in one study. There were no reports of serious adverse events. Most participants were in a positive fluid balance postoperatively (4.4 L IS and 2.5 L HS), with the excess significantly less in HS participants (MD -1.92 L, 95% confidence interval (CI) -2.61 to -1.22 L; P < 0.00001). IS participants received a mean volume of 2.4 L and HS participants received 1.49 L, significantly less fluid than IS-treated participants (MD -0.91 L, 95% CI -1.24 to -0.59 L; P < 0.00001). The maximum average serum sodium ranged between 138.5 and 159 in HS groups compared to between 136 and 143 meq/L in the IS groups. The maximum serum sodium was significantly higher in HS participants (MD 7.73, 95% CI 5.84 to 9.62; P < 0.00001), although the level remained within normal limits (136 to 146 meq/L).A high degree of heterogeneity appeared to be related to considerable differences in the dose of HS between studies. The quality of the evidence for the outcomes reported ranged from high to very low. The risk of bias for many of the studies could not be determined for performance and detection bias, criteria that we assess as likely to impact the study outcomes.

AUTHORS' CONCLUSIONS

HS reduces the volume of intravenous fluid required to maintain people undergoing surgery but transiently increases serum sodium. It is not known if HS affects survival and morbidity, but this should be examined in randomized controlled trials that are designed and powered to test these outcomes.

Infarct volume after hyperacute infusion of hypertonic saline in a rat model of acute embolic stroke

INTRODUCTION

Hypertonic saline (HS) can treat cerebral edema arising from a number of pathologic conditions. However, physicians are reluctant to use it during the first 24 h after stroke because of experimental evidence that it increases infarct volume when administered early after reperfusion. Here, we determined the effect of HS on infarct size in an embolic clot model without planned reperfusion.

METHODS

A clot was injected into the internal carotid artery of male Wistar rats to reduce perfusion in the middle cerebral artery territory to less than 40 % of baseline, as monitored by laser-Doppler flowmetry. After 25 min, rats were randomized to receive 10 mL/kg of 7.5 % HS (50:50 chloride:acetate) or normal saline (NS) followed by a 0.5 mL/h infusion of the same solution for 22 h.

RESULTS

Infarct volume was similar between NS and HS groups (in mm(3): cortex 102 ± 65 mm(3) vs. 93 ± 49 mm(3), p = 0.72; caudoputamenal complex 15 ± 9 mm(3) vs. 21 ± 14, p = 0.22; total hemisphere 119 ± 76 mm(3) vs. 114 ± 62, p = 0.88, respectively). Percent water content was unchanged in the infarcted hemisphere (NS 81.6 ± 1.5 %; HS 80.7 ± 1.3 %, p = 0.16), whereas the HS-treated contralateral hemisphere was significantly dehydrated (NS 79.4 ± 0.8 %; HS 77.5 ± 0.8 %, p < 0.01).

CONCLUSIONS

HS reduced contralateral hemispheric water content but did not affect ipsilateral brain water content when compared to NS. Infarct volume was unaffected by HS administration at all evaluated locations.

Comparison of 7.2% hypertonic saline - 6% hydroxyethyl starch solution and 6% hydroxyethyl starch solution after the induction of anesthesia in patients undergoing elective neurosurgical procedures

OBJECTIVE

The ideal solution for fluid management during neurosurgical procedures remains controversial. The aim of this study was to compare the effects of a 7.2% hypertonic saline - 6% hydroxyethyl starch (HS-HES) solution and a 6% hydroxyethyl starch (HES) solution on clinical, hemodynamic and laboratory variables during elective neurosurgical procedures.

METHODS

Forty patients scheduled for elective neurosurgical procedures were randomly assigned to the HS-HES group orthe HES group. Afterthe induction of anesthesia, patients in the HS-HES group received 250 mL of HS-HES (500 mL/h), whereas the patients in the HES group received 1,000 mL of HES (1000 mL/h). The monitored variables included clinical, hemodynamic and laboratory parameters. Chictr.org: ChiCTR-TRC-12002357

RESULTS

The patients who received the HS-HES solution had a significant decrease in the intraoperative total fluid input (p<0.01), the volume of Ringer's solution required (p<0.05), the fluid balance (p<0.01) and their dural tension scores (p<0.05). The total urine output, blood loss, bleeding severity scores, operation duration and hemodynamic variables were similar in both groups (p>0.05). Moreover, compared with the HES group, the HS-HES group had significantly higher plasma concentrations of sodium and chloride, increasing the osmolality (p<0.01).

CONCLUSION

Our results suggest that HS-HES reduced the volume of intraoperative fluid required to maintain the patients undergoing surgery and led to a decrease in the intraoperative fluid balance. Moreover, HS-HES improved the dural tension scores and provided satisfactory brain relaxation. Our results indicate that HS-HES may represent a new avenue for volume therapy during elective neurosurgical procedures.

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.

Hypertonic saline for peri-operative fluid management

BACKGROUND

Fluid excess may place patients undergoing surgery at risk for various complications. Hypertonic saline (HS) maintains intravascular volume with less intravenous fluid than isotonic salt (IS) solutions, but may increase serum sodium.

OBJECTIVES

To determine the benefits and harms of HS versus IS solutions administered to patients undergoing surgery.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library) Issue 1, 2009; MEDLINE (1966 to 2009); EMBASE (1980 to 2009); LILACS (to August 2009) and CINAHL (1982 to 2009) without language restrictions.

SELECTION CRITERIA

We included randomized clinical trials where HS was compared to IS in patients undergoing surgery, irrespective of blinding, language, and publication status.

DATA COLLECTION AND ANALYSIS

We assessed the impact of HS administration on mortality, organ failure, fluid balance, serum sodium, serum osmolarity, diuresis and physiologic measures of cardiovascular function. We pooled data using odds ratio or mean difference (MD) for binary and continuous outcomes, respectively, using random-effects models.

MAIN RESULTS

We included 15 studies with 614 participants. One death in each group and no other serious adverse events were reported. While all patients were in a positive fluid balance postoperatively, the excess was significantly less in HS patients (standardized mean difference (SMD) -1.43L, 95% confidence interval (CI) 0.8 to 2.1 L less; P < 0.00001). Patients treated with HS received significantly less fluid than IS-treated patients (MD -2.4L 95% (CI) 1.5 to 3.2 L less; P < 0.00001) without differences in diuresis between the groups. Maximum intraoperative cardiac index was significantly increased with HS (SMD 0.6 L/min/M2 higher, 95% CI 0.1 to 1.0, P = 0.02) but Intraoperative pulmonary artery wedge pressure remained unchanged. While the maximum serum sodium and the serum sodium at the end of the study were significantly higher in HS patients, the level remained within normal limits (136 to 146 meq/L).

AUTHORS' CONCLUSIONS

HS reduces the volume of intravenous fluid required to maintain patients undergoing surgery but transiently increases serum sodium. It is not known if HS effects patient survival and morbidity but it should be tested in randomized clinical trials that are designed and powered to test these outcomes.

Operating room use of hypertonic solutions: a clinical review

Hyperosmotic-hyperoncotic solutions have been widely used during prehospital care of trauma patients and have shown positive hemodynamic effects. Recently, there has been a growing interest in intra-operative use of hypertonic solutions. We reviewed 30 clinical studies on the use of hypertonic saline solutions during surgeries, with the majority being cardiac surgeries. Reduced positive fluid balance, increased cardiac index, and decreased systemic vascular resistance were the main beneficial effects of using hypertonic solutions in this population. Well-designed clinical trials are highly needed, particularly in aortic aneurysm repair surgeries, where hypertonic solutions have shown many beneficial effects. Examining the immunomodulatory effects of hypertonic solutions should also be a priority in future studies.

Effects of hyperoncotic or hypertonic-hyperoncotic solutions on polymorphonuclear neutrophil count, elastase- and superoxide-anion production: a randomized controlled clinical trial in patients undergoing elective coronary artery bypass grafting

BACKGROUND

Hypertonic-hyperoncotic solutions may be an effective treatment for systemic inflammatory response syndrome (SIRS). With regard to the immunomodulatory effects of these drugs, previous studies demonstrated controversial results. Therefore, the present study investigated the influence of different hyperoncotic and hypertonic-hyperoncotic solutions on polymorphonuclear neutrophil leukocyte (PMNL) count, elastase and superoxide-anion production in patients undergoing elective coronary artery bypass grafting (CABG) with cardiopulmonary bypass.

METHODS

Fifty patients scheduled for elective CABG with cardiopulmonary bypass were randomly assigned to five groups: (i) NaCl 0.9%, 750 ml/m(2) body surface area (BSA); (ii) hydroxyethylic starch 10%, 250 ml/m(2) BSA and NaCl 0.9%, 400 ml/m(2) BSA; (iii) dextran 10%, 250 ml/m(2) BSA and NaCl 0.9%, 300 ml/m(2) BSA; (iv) hypertonic sodium chloride 7.2%/hyperoncotic hydroxyethylic starch 10%, 150 ml/m(2) BSA; and (v) hypertonic sodium chloride 7.2%/hyperoncotic dextran 10%, 150 ml/m(2) BSA. Blood samples were drawn from arterial, central venous and coronary artery sinus catheters peri-operatively. PMNL count, superoxide-anion production and elastase were recorded.

RESULTS

PMNL counts and elastase activity increased in all groups after reperfusion. Superoxide-anion production showed only minor changes. Between groups, no significant differences were demonstrated.

CONCLUSIONS

Infusion of clinically relevant doses of hypertonic-hyperoncotic solution did not affect PMNL count, elastase- or superoxide-anion production during elective CABG with cardiopulmonary bypass.

The immunomodulatory effects of hypertonic saline resuscitation in patients sustaining traumatic hemorrhagic shock: a randomized, controlled, double-blinded trial

OBJECTIVE

To investigate the potential immunologic and anti-inflammatory effects of hypertonic saline plus dextran (HSD) in hemorrhagic trauma patients.

BACKGROUND

Unbalanced inflammation triggered by shock has been linked to multiorgan dysfunction (MOD) and death. In animal and cellular models, HSD alters the inflammatory response to shock, attenuating MOD and improving outcome. It remains untested whether HSD has similar effects in humans.

METHODS

A single 250-mL dose of either HSD (7.5% NaCl, 6% dextran-70) or placebo (0.9% NaCl) was administered to adult blunt trauma patients in hemorrhagic shock. The primary outcome was to measure changes in immune/inflammatory markers, including neutrophil activation, monocyte subset redistribution, cytokine production, and neuroendocrine changes. Patient demographics, fluid requirements, organ dysfunction, infection, and death were recorded.

RESULTS

A total of 27 patients were enrolled (13 HSD) with no significant differences in clinical measurements. Hyperosmolarity was modest and transient, whereas the immunologic/anti-inflammatory effects persisted for 24 hours. HSD blunted neutrophil activation by abolishing shock-induced CD11b up-regulation and causing CD62L shedding. HSD altered the shock-induced monocyte redistribution pattern by reducing the drop in "classic" CD14 and the expansion of the "pro-inflammatory" CD14CD16 subsets. In parallel, HSD significantly reduced pro-inflammatory tumor necrosis factor (TNF)-alpha production while increasing anti-inflammatory IL-1ra and IL-10. HSD prevented shock-induced norepinephrine surge with no effect on adrenal steroids.

CONCLUSIONS

This first human trial evaluating the immunologic/anti-inflammatory effects of hypertonic resuscitation in trauma patients demonstrates that HSD promotes a more balanced inflammatory response to hemorrhagic shock, raising the possibility that similar to experimental models, HSD might also attenuate post-trauma MOD.

Immune effect of hypertonic saline: fact or fiction?

Hypertonicity affects many parts of the immune system. Animal studies and experiments in isolated cell cultures show that hypertonicity reversibly suppresses several neutrophil functions and at the same time up-regulates T-lymphocyte function. Infusion of hypertonic saline with or without colloids may thus, besides providing efficient plasma volume expansion, ameliorate the detrimental consequences on the immune function of trauma, shock, reperfusion, and major surgery. However, the few clinical studies conducted to date, specifically addressing the immune effect of hypertonic saline infusion, have shown little, if any, effect on markers of immune function, and larger clinical trials have not demonstrated benefit in terms of morbidity or mortality. Thus, as opposed to animal and cell-culture studies, the immune-modulating properties of hypertonic saline infusion would appear to be of limited value in clinical practice. This review presents in vitro studies, animal experiments, and clinical trials which investigated the consequences of hypertonic saline on markers of immune function.