Figure 1

Cardiac output, heart frequency, mean systemic arterial pressure and mean pulmonary artery pressure before NPWT is applied (0 min) and 2½ and 5 min after a negative pressure of -120 mmHg was applied. Measurements were made during NPWT using gauze or two different types of foam. The results are shown as means ± the standard error on the mean of eight experiments. Each of the 8 pigs was subjected to NPWT using all 3 different dressings (n = 8). Statistical analysis was performed using the Mann-Whitney test. Significance was defined as P < 0.05 (*), P < 0.01 (**), P < 0.001 (***) and P > 0.05 (not significant, n.s.). Before negative pressure was applied, baseline heart frequency was 114 ± 1 bpm, cardiac output was 3.0 ± 0.1 L/min, mean systemic arterial pressure was 85 ± 3 mmHg and mean pulmonary artery pressure was 17.5 ± 0.5 mmHg. Note that heart frequency decreases during NPWT using foam, but not gauze. Results were similar at the other negative pressures studied (not shown).