Intraoperative Hypoxemia in Thoracic Surgery: Impact on early outcome.
Authors: Deligianni M, Fyntanidou B, Foroulis Ch, Kioumis I, Tsagkaropoulos S, Alexiou I, Kotzampassi K, Grosomanidis V
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Introduction: Anesthesia for thoracic surgery presents specific challenges since anesthesiologists have to manage patients with several comorbidities, apply One Lung Ventilation (OLV) to facilitate surgery and at the same time they should try to maintain adequate safe oxygen levels. Hypoxemia is a common consequence of OLV. The aim of the present retrospective study was to investigate the impact of intraoperative hypoxia on the early outcome of patients. Material and Methods: In this study120 patients were included, who underwent thoracic surgical procedures with OLV and were assigned into two groups of 60 patients in each group. Group A consisted of patients who experienced severe hypoxia (PiO2/FiO2<100) during OLV, whereas Group B consisted of those who did not suffer from hypoxia. ABG samples were collected intraoperatively at four different phases: Ph1: spontaneous breathing without any oxygen supply before intubation, Ph2: after initiation of mechanical ventilation, Ph3: during OLV and Ph4: immediately before being transferred from the operating theatre. Venous blood samples were collected at three phases: Ph1: after initiation of mechanical ventilation, Ph2: at the time of hypoxia occurrence and Ph3: immediately before being transferred from the operating theatre. During ICU stay, ABG samples were taken at four phases: Ph1: immediately after ICU admission, Ph2: before extubation, Ph3: after extubation and Ph4: before ICU discharge. Results: Intraoperatively, patients in Group B had better oxygenation compared to Group A at all phases. Moreover, during OLV patients in Group A experienced severe hypoxemia. Intraoperative PO2/FiO2 ratio in Group A was 369,8±69,9 / 279,4 ±91,5 / 68,3±11,8 / 324,7± 82,9 and at the corresponding phases the relevant values in Group B were 420,8±68,2 / 373,8±87,5/ 242,9±79,6 / 406,7±64,4. Partial pressure of oxygen in the central venous blood (PcvO2) and Central venous oxygen saturation (ScvO2) differed in a statistically significant manner between the study groups. However, ScvO2 remained at acceptable levels even at the time of hypoxemia in Group A. ScvO2 values in Group A were 78,7±9,1 / 66,8±79,7 / 73,3±5,82 and at the corresponding phases the relevant values in Group B were 87,1±7,2 / 79,8±7,8 / 81,8±7,5. Duration of mechanical ventilation in ICU was longer in Group A compared to Group B (5,34±5,1hrs vs 3,6±2,5hrs), whereas ICU and total hospital stay did not differ between study groups. Conclusion: Hypoxemia during OLV in Group A did not have a negative impact on early outcome of patients.