Hypertonic Saline Dextran Ameliorates Organ Damage in Beagle Hemorrhagic Shock

Abstract

Objective: The goal of this study was to investigate the effect of hypertonic saline with 6% Dextran-70 (HSD) resuscitation on organ damage and the resuscitation efficiency of the combination of HSD and lactated ringers (LR) in a model of hemorrhage shock in dogs.

Methods: Beagles were bled to hold their mean arterial pressure (MAP) at 50 ± 5 mmHg for 1 h. After hemorrhage, beagles were divided into three groups (n = 7) to receive pre-hospital resuscitation for 1 h (R1): HSD (4 ml/kg), LR (40 ml/kg), and HSD+LR (a combination of 4 ml/kg HSD and 40 ml/kg LR). Next, LR was transfused into all groups as in-hospital resuscitation (R2). After two hours of observation (R3), autologous blood was transfused. Hemodynamic responses and systemic oxygenation were measured at predetermined phases. Three days after resuscitation, the animals were sacrificed and tissues including kidney, lung, liver and intestinal were obtained for pathological analysis.

Results: Although the initial resuscitation with HSD was shown to be faster than LR with regard to an ascending MAP, the HSD group showed a similar hemodynamic performance compared to the LR group throughout the experiment. Compared with the LR group, the systemic oxygenation performance in the HSD group was similar but showed a lower venous-to-arterial CO2 gradient (Pv-aCO2) at R3 (p < 0.05). Additionally, the histology score of the kidneys, lungs and liver were significantly lower in the HSD group than in the LR group (p < 0.05). The HSD+LR group showed a superior hemodynamic response but higher extravascular lung water (EVLW) and lower arterial oxygen tension (PaO2) than the other groups (p < 0.05). The HSD+LR group showed a marginally improved systemic oxygenation performance and lower histology score than other groups.

Conclusions: Resuscitation after hemorrhagic shock with a bolus of HSD showed a similar hemodynamic response compared with LR at ten times the volume of HSD, but HSD showed superior efficacy in organ protection. Our findings suggest that resuscitation with the combination of HSD and LR in the pre-hospital setting is an effective treatment.

Fig 1. Experimental protocol.

Following an equilibration period, baseline (BL) measurements of all parameters were recorded, and subsequent blood was rapidly withdrawn until a mean arterial pressure of approximately 50±5 mm Hg was reached and maintained for another 60 minutes (hypovolemia period). All measurements were then recorded (post-hemorrhage, PH, time = 0 min), and the animals were separately resuscitated with HSD, LR or HSD+LR over 60 minutes (Resuscitation1, R1, time = 60 min). Then, during the in-hospital resuscitation phase, LR were started as a transfusion for all animals until the MAP reached 85% of the baseline value (Resuscitation 2, R2, time = 120 min). After a two-hour observation period (Resuscitation 3, R3, time = 240 min), all animals received blood transfusions (70% of their blood loss) so that they would survive for three days of observation. Then, the dogs were sacrificed with an IV bolus injection of pentobarbital, and their tissues including their kidneys, lungs, liver and intestines were obtained for pathological analysis.

Fig 2. MAP in the LR, HSD and HSD+LR groups, measured at different time intervals.

Pre-hospital resuscitation (0-60min) from hemorrhagic shock respectively with (1) 40ml/kg lactated ringers at a constant rate of 20 ml/min (LR group), (2) a bolus of HSD (4ml/kg) over a fixed interval of 2 min (HSD group), or (3) an initial bolus of HSD (4ml/kg) with a continued infusion of 40ml/kg Lactated Ringer (HSD+LR group). Subsequently all groups were injected with lactated ringers in in-hospital (60-90min) until the MAP reached 85% of the baseline level. *P<0.05 vs LR (black square); ^#P<0.05 vs HSD (open circle); ^&P<0.05 vs HSD+LR (shaded triangle). n = 7 for all groups.

Fig 3. Hemodynamic parameters changes after hemorrhagic shock and resuscitation.

Pre-hospital resuscitation (0-60min) from hemorrhagic shock respectively with (1) 40ml/kg lactated ringers at a constant rate of 20 ml/min (LR group), (2) a bolus of HSD (4ml/kg) over a fixed interval of 2 min (HSD group), or (3) an initial bolus of HSD (4ml/kg) with a continued infusion of 40ml/kg Lactated Ringer (HSD+LR group). Subsequently all groups were injected with lactated ringers in in-hospital (60-90min) until the MAP reached 85% of the baseline level. (A) cardiac index (CI). (B) systolic volume index (SVI). (C) global end-diastolic index (GEDVI). (D) total intrathoracic blood index (ITBI). (E) systemic vascular resistance index (SVRI). (F) extravascular lung water (EVLW) (G) pulmonary vascular permeability index (PVPI). (H) arterial oxygen tension (PaO₂). *P<0.05 vs LR (black square); ^#P<0.05 vs HSD (open circle); ^&P<0.05 vs HSD+LR (shaded triangle). n = 7 for all groups.

Fig 4. The changes of MAP and CI in the LR and HSD group during the pre-hospital period.

(A) mean arterial pressure (MAP). (B) cardiac index (CI). A bolus of HSD (4ml/kg) was injected intravenously over a fixed interval of 2 min (HSD group). While, 40ml/kg Lactated ringers were intravenously infused at a constant rate of 20 ml/min (LR group). Therefore, the HSD infusion was completed more quickly and thus produced a faster increase in the MAP and CI than those with the LR infusion. *P<0.05 vs LR (black square); ^#P<0.05 vs HSD (open circle). n = 7 for all groups.

Fig 5. Systemic oxygenation parameters in the LR, HSD and HSD+LR groups presented at baseline (BL, time = -90 min), end of controlled bleeding (post-hemorrhage, PH, time = 0 min), end of pre-hospital resuscitation (Resuscitation1, R1, time = 60 min), end of in-hospital resuscitation (Resuscitation2, R2, time = 120 min), and 3 h after in-hospital resuscitation (Resuscitation3, R3, time = 240 min).

(A) Systemic oxygen transport (DO₂). (B) Systemic oxygen uptake (VO₂). (C) Central venous oxygen saturation (ScvO2). (D) Venous-to-arterial CO₂ gradient (Pv-aCO₂). (E) Arterial lactate (Lac). (F) Hb concentration. *P<0.05 vs LR; ^#P<0.05 vs HSD. n = 7 for all groups.

Fig 6. Effect of different HSD resuscitation strategies on organ damage.

(A) The total urine output during the anesthetic period. (B) Plasma levels of urea nitrogen (BUN) and alanine aminotransferase (AST) measured at baseline (BL, time = -90 min), end of controlled bleeding (post-hemorrhage, PH, time = 0 min), 3 h after in-hospital resuscitation (Resuscitation3, R3, time = 240 min), and after one to three days of resuscitation (1d, 2d, 3d); After three days of resuscitation, the dogs were sacrificed and their tissues including kidney, lung, liver and intestinal were obtained for histological analysis. (C) Kidney histologic scores and appearance. (D) Lung histologic scores and appearance. (E) Liver histologic scores and appearance. (F) Intestinal histologic scores and appearance. H&E staining and Periodic Acid-Schiff staining for organs. original magnification, 200×. *P<0.05 vs LR; ^#P<0.05 vs HSD. n = 6 for all groups.