Study of the effects of high volume hemofiltration on extra vascular lung water and alveolar-arterial oxygen exchange in patients with septic shock

Abstract

To explore the effects of high volume hemofiltration (HVHF) on inflammatory factors, extra vascular lung water and alveolar-arterial oxygen exchange in patients with septic shock. The data of 87 patients with septic shock underwent fluid resuscitation admitted to intensive care unit (ICU) of Shandong Provincial Hospital Affiliated to Shandong University were retrospectively analyzed. According to whether HVHF was used or not, all the patients were divided into fluid resuscitation group (n=41) and HVHF group (n=46). The patients in HVHF group received bedside high volume continuous vein-vein hemofiltration for at least 3 days on the basis of fluid resuscitation. The inflammatory factors, indexes of heart function, hemodynamics monitored by pulse-indicated continuous cardiac output (PiCCO), oxygen exchange, the severity of the disease before and after treatment, and 28-day mortality were compared between the two groups. The relationship between extra-vascular lung water index (EVLWI) and alveolar-arterial oxygen pressure difference (P(A-a)DO₂) was analyzed. (1) After treatment, the serum levels of interleukin-6 (IL-6), procalcitonin (PCT), and N-terminal pro-B-type natriuretic peptide (NT(-pro)BNP) in both group were gradually decreased. The IL-6, PCT, and NT(-pro)BNP on the 3rd day after treatment in HVHF group were significantly lower than those in fluid resuscitation group [IL-6 (μg/L): 34.8 ± 15.8 vs. 63.3 ± 21.2, PCT (μg/L): 7.5 ± 6.4 vs. 17.3 ± 11.2, NT(-pro)BNP (μg/L): 561.8 ± 23.7 vs. 584.3 ± 56.7, P<0.05 or P<0.01]. (2) The hemodynamics indexes were improved after treatment in both groups. The levels of intrathoracic blood volume index (ITBVI), EVLWI and pulmonary vascular permeability index (PVPI) on the 3rd day after treatment in HVHF group were significantly lower than those in fluid resuscitation group [ITBVI (mL/m²): 634.2 ± 125.8 vs. 963.8 ± 321.0, EVLWI (mL/kg): 7.5 ± 2.4 vs. 12.3 ± 4.2, PVPI: 2.2 ± 1.2 vs. 4.2 ± 2.0, all P<0.01]. (3) The levels of PA-aDO₂and arterial blood lactic (Lac) were gradually decreased, and oxygenation index (PaO₂/FiO₂) was gradually increased in both groups. Compared with fluid resuscitation group, the P(A-a)DO₂and Lac on the 3rd and the 7th day were significantly declined[P(A-a)DO₂(mmHg, 1 mmHg=0.133 kPa) on the 3rd day: 252.37 ± 29.45 vs. 270.82 ± 38.07, on the 7th day: 181.08 ± 21.81 vs. 221.02 ± 29.13; Lac (mmol/L) on the 3rd day: 3.17 ± 2.03 vs. 4.07 ± 2.43, on the 7th day: 1.95 ± 0.97 vs. 2.45 ± 1.07, P<0.05 or P<0.01], and the PaO₂/FiO₂on the 7th day was significantly elevated (mmHg: 258 ± 41 vs. 178 ± 34, P<0.01). (4) A significant positive correlation was found between EVLWI and P(A-a)DO₂(r=0.693, P=0.001), with the 95% confident interval (95% CI) 0.617-0.773. (5) The condition was improved after treatment in the two groups. The acute physiology and chronic health evaluationII (APACHEII) scores and sepsis-related organ failure assessment (SOFA) scores on the 7th day after treatment in HVHF group were significantly reduced compared with those in fluid resuscitation group (APACHEII score on the 3rd day: 18.2 ± 7.7 vs. 22.4 ± 8.6, on the 7th day: 8.2 ± 3.8 vs. 17.2 ± 6.8; SOFA score on the 3rd day: 13.6 ± 3.4 vs. 15.8 ± 5.0, on the 7th day: 7.6 ± 3.3 vs. 12.8 ± 3.9, P<0.05 or P<0.01). The 28-day mortality in HVHF group was significantly lower than that in fluid resuscitation group [15.22% (7/46) vs. 34.15% (14/41), χ² = 4.242, P=0.038]. HVHF could decrease blood inflammatory factors, and reduce the vaso-permeability and extra vascular lung water with a result of the improvement of the levels of alveolar- arterial oxygen exchange in patients with septic shock and the prognosis at the same time.