['This study is to evaluate the effect of high-volume hemofiltration (HVHF) and early goal-directed therapy (EGDT) on alveolar-arterial oxygen exchange in patients with refractory septic shock.', 'Patients were classified into two groups by a prospective cohort study: 86 received both HVHF and EGDT (the HVHF group), and 81 treated with EGDT only (the control group). Alveolar-arterial oxygen pressure was taken at baseline and at days 1, 3, and 7, and respiratory index (RI, ratio of P(a)O2 alveolar-arterial oxygen pressure difference (P(A-a)DO2) to arterial oxygen pressure (P(a)O2) was calculated.', 'At day 7, the levels of central venous and arterial blood oxygen content were significantly higher in the HVHF vs. the control group (both with p < 0.05). The level of oxygen extraction ratio (O2ER) was significantly higher in the HVHF than the control group (p < 0.01). The levels of P(A-a)DO2 and RI were significantly lower in the HVHF than the control group (p < 0.05 and p < 0.01, respectively). RI and the ratio of P(a)O2 to the fraction of inspired oxygen were significantly higher in the HVHF than the control group (p < 0.05 and p < 0.01, respectively). The acute physiology and chronic health evaluation score and the sequential organ failure assessment score in the HVHF group were significantly lower compared to the control group (p < 0.01 and p < 0.05, respectively). At day 28, the mortality rate was lower in the HVHF vs. the control group (p < 0.01).'] Does high-volume hemofiltration combined with early goal-directed therapy improve alveolar-arterial oxygen exchange in patients with refractory septic shock?