Experimental models may help to understand the pathophysiology of septic shock. The aim of this study is to evaluate effects of different volumes of Lactate Ringer's solution (RL) on cardiovascular function and intestinal perfusion in experimental hypodynamic septic shock. Anesthetized, ventilated mongrel dogs (n = 21, 16.3 ± 1.9 kg) received an intravenous injection of 1.2 × 1010/kg cfu live Escherichia coli over 30 min (baseline–T30). Then, the animals were randomized to receive 16 ml/kg RL (n = 7), 32 ml/kg RL infused over a 30-min period or a control group (no fluid resuscitation, n = 7) (T60–T90). The animals were followed for 2 hours thereafter (T90–T210). Systemic hemodynamics were determined by arterial and pulmonary artery catheters. Portal and renal vein blood flows were measured with ultrasonic flowprobes. The PCO2 gap (gas tonometry), arterial and portal vein lactate levels were measured at each timepoint. The data are expressed as mean ± SEM. The different variables were analyzed by analysis of variance.
Live E. coli injection in dogs promotes low cardiac output, systemic and regional lactic acidosis and severe splanchnic hypoperfusion. The RL solution promoted only modest and transient improvement in blood flows but not in systemic and regional acidosis. There were no differences between the resuscitated groups.
Table 1.
| Baseline | T30 | T90 | T210 | |
|---|---|---|---|---|
| Mean arterial pressure (mmHg) | ||||
| Control | 105.9 ± 4.6 | 93.8 ± 4.6a | 62.8 ± 7.6 | 79.5 ± 5.9 |
| RL, 16 ml/kg | 108.7 ± 4.0 | 98.0 ± 5.2a | 75.1 ± 7.3 | 88.9 ± 8.9 |
| RL, 32 ml/kg | 107.0 ± 2.9 | 91.1 ± 3.5a | 89.8 ± 6.1 | 92.1 ± 3.3 |
| Cardiac index (l/min/m2) | ||||
| Control | 2.92 ± 0.09 | 1.78 ± 0.18a | 1.39 ± 0.13 | 1.32 ± 0.06 |
| RL, 16 ml/kg | 3.23 ± 0.35 | 2.30 ± 0.34a | 2.40 ± 0.46b | 1.35 ± 0.19 |
| RL, 32 ml/kg | 3.10 ± 0.08 | 1.73 ± 0.18a | 2.68 ± 0.26b | 1.52 ± 0.09 |
| Portal vein flow index (ml/min/m2) | ||||
| Control | 697.8 ± 62.2 | 390.9 ± 70.6a | 225.2 ± 34.2 | 183.5 ± 32.3 |
| RL, 16 ml/kg | 591.9 ± 41.5 | 311.6 ± 25.4a | 320.7 ± 47.1b | 201.5 ± 18.9 |
| RL, 32 ml/kg | 632.8 ± 25.5 | 244.5 ± 32.3a | 441.0 ± 59.2b | 162.0 ± 12.4 |
| PCO2 gap (mmHg) | ||||
| Control | 5.0 ± 2.7 | 12.6 ± 4,1a | 33.1 ± 4.2 | 44.3 ± 5.3 |
| RL, 16 ml/kg | 2.4 ± 0.9 | 15.0 ± 4.2a | 22.7 ± 2.3 | 48.6 ± 3.4 |
| RL, 32 ml/kg | 0.6 ± 2.3 | 6.4 ± 2.8a | 13.8 ± 2.2 | 35.3 ± 2.5 |
| Arterial lactate (mmol/l) | ||||
| Control | 1.34 ± 0.18 | 1.53 ± 0.17a | 2.91 ± 0.29 | 3.33 ± 0.32 |
| RL, 16 ml/kg | 1.58 ± 0.17 | 1.72 ± 0.29 | 4.23 ± 0.30 | 5.63 ± 0.37 |
| RL, 32 ml/kg | 0.97 ± 0.20 | 1.77 ± 0.21a | 3.8.7 ± 0.54 | 2.57 ± 0.40 |
aP < 0.05 vs BL, bP < 0.05 vs control group. RL, Lactate Ringer's solution.