Isochloremic hypertonic solutions for severe hemorrhage

Mechanobiological Adaptation to Hyperosmolarity Enhances Barrier Function in Human Vascular Microphysiological System

In infectious disease such as sepsis and COVID-19, blood vessel leakage treatment is critical to prevent fatal progression into multi-organ failure and ultimately death, but the existing effective therapeutic modalities that improve vascular barrier function are limited. Here, this study reports that osmolarity modulation can significantly improve vascular barrier function, even in an inflammatory condition. 3D human vascular microphysiological systems and automated permeability quantification processes for high-throughput analysis of vascular barrier function are utilized. Vascular barrier function is enhanced by >7-folds with 24-48 h hyperosmotic exposure (time window of emergency care; >500 mOsm L^-1 ) but is disrupted after hypo-osmotic exposure (<200 mOsm L^-1 ). By integrating genetic and protein level analysis, it is shown that hyperosmolarity upregulates vascular endothelial-cadherin, cortical F-actin, and cell-cell junction tension, indicating that hyperosmotic adaptation mechanically stabilizes the vascular barrier. Importantly, improved vascular barrier function following hyperosmotic exposure is maintained even after chronic exposure to proinflammatory cytokines and iso-osmotic recovery via Yes-associated protein signaling pathways. This study suggests that osmolarity modulation may be a unique therapeutic strategy to proactively prevent infectious disease progression into severe stages via vascular barrier function protection.

Volume replacement and microhemodynamic changes in polytrauma

Though fluid administration is one of the most basic concepts in resuscitation, there is ongoing controversy and continuing research on the definition of the ideal fluid for resuscitation of trauma and hemorrhage and for intraoperative volume support. In general, crystalloids and colloids, as well as blood, blood substitutes and oxygen therapeutics, are available. This report briefly revisits the physiological mechanisms underlying resuscitation with crystalloids and colloids, emphasizing colloid-supplemented resuscitation with hypertonic saline. Finally, potential applications of oxygen therapeutics are briefly considered.

First Use of Hypertonic Saline Dextran in Children: A Study in Safety and Effectiveness for Atrial Septal Defect Surgery

Hypertonic saline dextran (7.5% NaCl + 6% Dextran-70) has been used in adults in several studies and shown beneficial effects in hypovolemic shock, trauma, cardiogenic shock, and cardiac surgery. There have never been studies of this solution in children. This work studies its effect in children undergoing surgery for the correction of atrial septal defects. Twenty-five children underwent correction of atrial septal defect using cardiopulmonary bypass with bloodless priming. Children were divided in five groups and each received an incremental hypertonic saline dextran dose of 0.1, 0.5, 1.0, 2.0, and 4.0 mL/kg, 5 min before the beginning of cardiopulmonary bypass. Collected data were fluid balance, amount of bleeding, blood/derivative transfusion occurrence, plasma sodium, and hematocrit. Patients were divided into low-dose (0-1 mL/kg) and high-dose (2-4 mL/kg) groups. Analysis of variance was used to determine differences in blood loss between groups. The fluid balance and blood/derivative requirements were compared through Student's t test and Fisher's exact test (2-tail), respectively. All patients were discharged from hospital with corrected atrial septal defect. No hypertonic saline dextran-related complications occurred. There were no differences in the amount of bleeding. The high-dose group exhibited a significant decrease in fluid balance and in blood/derivative requirements in comparison with the low-dose group. In this study, the use of hypertonic saline dextran in the pediatric population submitted to cardiopulmonary bypass is safe and does not raise the amount of bleeding. Its effective doses produce negative fluid balance and reduce blood/derivative requirements.

Fluid resuscitation improves hemodynamics without increased bleeding in a model of uncontrolled hemorrhage induced by an iliac artery tear in dogs

BACKGROUND

Fluid resuscitation administered before hemorrhage control for trauma victims sustaining penetrating abdominal injury is controversial. Our objective was to evaluate intra-abdominal blood loss and hemodynamic and metabolic effects of no fluid resuscitation, small-volume 7.5% sodium chloride/6% dextran-70 (HSD), or large-volume lactated Ringer's (LR) solution during intra-abdominal vascular injury and uncontrolled hemorrhage.

METHODS

In pentobarbital-anesthetized dogs (n = 26, 17 +/- 0.3 kg), a suture was placed through the common iliac artery to produce a 3-mm tear when the exteriorized suture lines were pulled after incision closure. Dogs were randomized to three groups, according to the treatment used after 20 minutes of uncontrolled hemorrhage: controls, no fluid resuscitation (CT group) (n = 6); the HSD group (4 mL/kg over 4 minutes, n = 6); and the LR group (32 mL/kg over 15 minutes, n = 6). After 40 minutes of uncontrolled bleeding, animals were killed, and intra-abdominal blood loss was measured.

RESULTS

Eight dogs died from severe hemorrhagic shock before randomization and were excluded. After 20 minutes, animals presented lower blood pressure (approximately 35 mm Hg), low cardiac output (approximately 1.0 L/min/m(2)), and metabolic acidosis (pH approximately 7.23, base excess approximately -9 mmol/L). After HSD and LR solution, arterial pressure presented a transient increase, but remained below baseline. Two animals died before the end of the experiment, both in the LR group. Cardiac index was partially improved in the LR and HSD groups, whereas the CT group sustained a low-flow state. There were no significant differences between groups regarding intra-abdominal blood loss (CT group, 47.8 +/- 5.9 mL/kg; HSD group, 41.7 +/- 2.3 mL/kg; and LR group, 49.4 +/- 0.7 mL/kg).

CONCLUSION

Fluid resuscitation with either large-volume LR solution or small-volume HSD, during uncontrolled hemorrhage from intra-abdominal vascular injury, produced hemodynamic and metabolic benefits, without additional blood loss, whereas no fluid resuscitation was associated with sustained low cardiac output and hypotension.

[Hemodynamic effects of hypertonic saline solutions]

Haemodynamic effects of hypertonic saline solutions (HSS) have been extensively studied in animals and humans. Hypertonic sodium chloride (7.5%, 2,500 mOsm.L-1) either alone or combined with colloids, remains the standard solution. The haemodynamic response of HSS observed during treatment of hypovolaemic shock is explained by 1) an increase in preload due to the expansion of the plasma volume and a musculocutaneous vasoconstriction and 2) a decrease in systemic vascular resistance and afterload. A myocardial stimulation has been shown in various experimental conditions and in humans. However, the clinical relevance of this inotropic effect is questionable. Haemorrhagic shock is the main indication for small volume resuscitation with HSS. Other potential situations for the use of HSS are volume replacement in perioperative period, septic shock or burn injury and cardiopulmonary resuscitation. Before recommending the clinical use of HSS, additional clinical studies are required to substantiate the benefits of HSS over colloids.

Hypertonic acetate-alpha alpha hemoglobin for small volume resuscitation of hemorrhagic shock

Hypertonic acetate solution in small volumes greatly improves cardiac output and corrects acid-base disturbances in hemorrhaged animals. We hypothesized that the combination of alpha alpha-crosslinked human hemoglobin (alpha alpha Hb), an oxygen carrier and vasoconstrictor, with hypertonic sodium acetate (HAHb), a vasodilator, may be effective for small volume resuscitation of hemorrhagic shock. Six pigs hemorrhaged to a mean arterial pressure of 40 mmHg for 60 min (bled volume: 23.6 +/- 2.5 ml.kg-1) received a single bolus of 4 ml.kg-1 of HAHb infused over two min. HAHb restored arterial pressure, increased systemic vascular resistance and caused a modest increase in cardiac output and SvO2, while pulmonary arterial pressure and vascular resistance were markedly increased. In two animals, transient severe hypotension and low cardiac output may have been due to acute pulmonary hypertension during injection. Compared to our previous study, in which animals received 4 ml-kg-1 of alpha alpha Hb alone, HAHb produced higher cardiac output and a smaller increase in systemic and pulmonary vascular resistance. However, slower, titrated infusions may be needed when hemoglobin solutions are combined with drugs or solutions that cause vasodilation in order to decrease the likelihood of acute hemodynamic instability.

Resuscitation of uncontrolled liver hemorrhage: effects on bleeding, oxygen delivery, and oxygen consumption

Using a standardized liver injury model of uncontrolled hemorrhage, we tested the effect of different fluid resuscitation regimens on hemodynamics, oxygen delivery, oxygen consumption, bleeding volume, and fluid resuscitation requirements. Rats were randomized into three bolus resuscitation groups 15 minutes after liver injury: lactated Ringer's solution (LR, n = 10), hypertonic saline (HS, n = 10), and hypertonic sodium acetate (HA, n = 10). In all resuscitation groups, a 4 mL/kg bolus was first infused at a rate of 0.4 mL/min. Continuous supplemental LR infusion was then given for 90 minutes to maintain a mean arterial pressure of 80 mm Hg. An initial bolus of LR led to minimal changes in hemodynamics. Initial resuscitation with HS markedly increased blood pressure and cardiac index. The bolus of HA increased cardiac index but did not increase blood pressure; systemic vascular resistance was significantly decreased and bleeding significantly increased. Resuscitation with HS did not increase bleeding compared with LR and resulted in the smallest total resuscitation volume requirement. Resuscitation with HS and HA both resulted in a rapid increase in oxygen consumption; LR did not increase oxygen consumption. Animals in the HS group had significantly higher oxygen extraction ratios at the conclusion of the experiment. The use of different bolus fluids for the resuscitation of uncontrolled hemorrhage resulted in significant differences in hemodynamics, oxygen metabolism, and blood loss even when subsequent resuscitation was the same in all groups. Results from large vessel injury animal models and clinical studies of patients with penetrating trauma may not apply to solid parenchymal injuries.

Liver injury as a model of uncontrolled hemorrhagic shock: resuscitation with different hypertonic regimens

Using a standardized liver injury model of uncontrolled hemorrhage, we tested the effect of different hypertonic solutions on mortality, blood pressure, intra-abdominal bleeding, and circulating blood volume. After liver injury, rats were randomized to 4 groups: lactated Ringer's (LR, n = 10), Isosal (ISO, n = 10), hypertonic saline (HS, n = 10), and hypertonic sodium acetate (HA, n = 10). In all resuscitation groups, 4 mL/kg was infused at a rate of 0.4 mL/min. Blood volume was evaluated both directly and by estimation. Mortality was highest after HA resuscitation (40%) and lowest after HS resuscitation (0%), but this difference was not significant. Blood pressure was significantly higher after HS resuscitation, and this difference was sustained for 4 hours. The HA resuscitation did not increase blood pressure compared with LR resuscitation. Intraperitoneal blood volume was significantly higher with HS (25.5 +/- 0.7 mL/kg) and HA (26.8 +/- 1.2 mL/kg) than with LR (22.5 +/- 0.4 mL/kg). The HA resuscitation led to a significantly larger drop from baseline values of estimated terminal circulating blood volume than LR resuscitation. Nonparametric analysis combining survival time and directly measured change in blood volume demonstrated a significant advantage to HS, compared with LR. HA and HS resuscitations increased bleeding from uncontrolled solid viscus injury. The HS resuscitation restored blood pressure better than the other hypertonic solutions and maintained circulating blood volume in spite of increased bleeding. The HA and ISO resuscitations did not exhibit any advantage over LR in resuscitation of solid viscus injury.

An argument for colloid resuscitation for shock

A focused review of the physiologic mechanisms of colloid and crystalloid fluid resuscitations for acute critical illness is presented. This review suggests that postresuscitation plasma volume, cardiac output, left ventricular mechanical performance, and global and microcirculatory O2 supplies are more favorable with colloid therapy. Conversely, crystalloid may adversely affect microcirculatory blood flow and resultant O2 supply and use by ischemic tissues in shock. Poor relief of global and regional hypoxia may persist in critically ill patients after resuscitation with crystalloid.