INTRODUCTION: Ventilatory efficiency (V'E/V'CO2 ) has been shown to predict postoperative pulmonary complications (PPCs) in lung resection candidates. V'E/V'CO2 is determined by arterial partial pressure of carbon dioxide (P aCO2 ) and by dead space to tidal volume ratio (V D/V T). We hypothesised P aCO2 and V D/V T contribute equally to the increase in V'E/V'CO2 in lung resection patients. METHODS: Consecutive lung resection candidates from two prior prospective studies were included in this post hoc analysis. All subjects underwent preoperative spirometry, cardiopulmonary exercise testing and arterial blood gas analysis at rest and peak exercise. PPCs were prospectively assessed during the first 30 postoperative days, or hospital stay. A t-test, Mann-Whitney U-test and two-tailed Fisher's exact test were used to compare patients with and without PPCs. p-values <0.05 were considered statistically significant. RESULTS: Of 398 patients, PPC developed in 64 (16%). Patients with PPCs more frequently underwent lobectomy by open thoracotomy, had longer hospital and ICU length of stay and higher 30- and 90-day mortality. Moreover, patients with PPCs exhibited a higher V'E/V'CO2 ratio both at rest and peak exercise. Both ratios were independently associated with PPCs. At rest, the contribution of P aCO2 and V D/V T to the increase in V'E/V'CO2 ratio in patients with PPCs was 45% and 55%, respectively. At peak exercise, the contribution of P aCO2 and V D/V T to the increase in V'E/V'CO2 ratio was 16% and 84%, respectively. CONCLUSIONS: V D/V T (V'/Q' mismatch and/or rapid shallow breathing pattern) is the dominant contributor to the increase in V'E/V'CO2 in lung resection candidates who develop PPCs.

• Publication type
• Journal Article MeSH

INTRODUCTION: Post-operative oxygen therapy is used to prevent hypoxemia and surgical site infection. However, with improvements of anesthesia techniques, post-operative hypoxemia incidence is declining and the benefits of oxygen on surgical site infection have been questioned. Moreover, hyperoxemia might have adverse effects on the pulmonary and cardiovascular systems. We hypothesized hyperoxemia post thoracic surgery is associated with post-operative pulmonary and cardiovascular complications. METHODS: Consecutive lung resection patients were included in this post-hoc analysis. Post-operative pulmonary and cardiovascular complications were prospectively assessed during the first 30 post-operative days, or hospital stay. Arterial blood gases were analyzed at 1, 6 and 12 h after surgery. Hyperoxemia was defined as arterial partial pressure of oxygen (PaO2)>100 mmHg. Patients with hyperoxemia duration in at least two adjacent time points were considered as hyperoxemic. Student t-test, Mann-Whitney U test and two-tailed Fisher exact test were used for group comparison. P values < 0.05 were considered statistically significant. RESULTS: Three hundred sixty-three consecutive patients were included in this post-hoc analysis. Two hundred five patients (57%), were considered hyperoxemic and included in the hyperoxemia group. Patients in the hyperoxemia group had significantly higher PaO2 at 1, 6 and 12 h after surgery (p < 0.05). Otherwise, there was no significant difference in age, sex, comorbidities, pulmonary function tests parameters, lung surgery procedure, incidence of post-operative pulmonary and cardiovascular complications, intensive care unit and hospital length of stay and 30-day mortality. CONCLUSION: Hyperoxemia after lung resection surgery is common and not associated with post-operative complications or 30-day mortality.

• Keywords
• Hyperoxemia, Lung resection surgery, Post-operative complications,
• Publication type
• Journal Article MeSH