Monitoring pulse pressure variation during lung resection surgery

Although pulse pressure variation (PPV) is an effective dynamic parameter widely used to predict the increase in cardiac output after the administration of fluids in abdominal surgery, its use in thoracic surgery is controversial. A study was designed to describe the behaviour of PPV during lung resection surgery.

A prospective observational study was conducted on adult patients scheduled for lung resection surgery. Patients with bleeding greater than 200cc, or those who required vasopressors during data collection, were excluded. The PPV values were collected during different phases: in bipulmonary ventilation (T1), after the start of single lung ventilation, and the opening of the thorax (T2), at the end of the procedure prior to the restoration of the bipulmonary ventilation (T3), and after the closure of the thorax in bipulmonary ventilation (T4). The correlation coefficient of the PPV values at the different times was calculated.

The study included 50 consecutive patients. The mean values and standard deviations of PPV in the different phases were: T1, 11.14% (6.67); T2 6.24% (3.21, T3 5.68% (3.19), and T4 7.84% (4.61). The repeated ANOVA measurements found significant differences between the mean values of PPV in the different phases (P<.001). The correlation between the PPV values during T1 and T2 (PPVT1 and PPVT2) was r=0.868 ([P<.001], r2=0.753), while between T3 and T4 (PPVT3 and PPVT4) the correlation was r=0.616 ([P<.001], r2=0.379) between the PPV values in T3 and T4.

PPV presents a predictable behaviour in the course of lung resection surgery, characterised by a decrease of almost half at the beginning of the unipulmonary ventilation and opening of the thorax. It then remains stable throughout the surgery when there are no changes in the intravascular blood volume.