Development of atelectasis and arterial to end-tidal Pco2-difference in a porcine model of pneumoperitoneum

• Published in: British journal of anaesthesia : BJA Vol. 103; no. 2; pp. 298 - 303
• Main Authors: Strang, C.M., Hachenberg, T., Fredén, F., Hedenstierna, G.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2009; Oxford University Press
• Subjects: Anesthesia; Anesthesia, General - methods; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; atelectasis; Biological and medical sciences; Carbon Dioxide - blood; computed tomography; Disease Models, Animal; Female; Laparoscopy; lung; lung, atelectasis; Male; measurement techniques; measurement techniques, computed tomography; Medical sciences; MEDICIN; MEDICINE; model, pig; Oxygen - blood; Pa-Pe'(CO2) ratio; Partial Pressure; pig; Pneumoperitoneum, Artificial - adverse effects; Pulmonary Atelectasis - diagnostic imaging; Pulmonary Atelectasis - etiology; Respiration, Artificial - methods; Surgery; Surgery, laparoscopy; Sus scrofa; Tomography, X-Ray Computed; model, pig; measurement techniques, computed tomography; Pa–Pe′CO2 ratio; lung, atelectasis; partial pressure; Surgery, laparoscopy; a; ′; ratio; computed tomography; measurement techniques; Pneumoperitoneum; Pa-PE; Laparoscopy; Pig; lung; Vertebrata; Mammalia; Partial pressure; Atelectasis; Measurement technique; Abdominal disease; Surgery; Tomography; Anesthesia; model; Artiodactyla; Ungulata
• ISSN: 0007-0912; 1471-6771; 1471-6771
• DOI: 10.1093/bja/aep102

Intraperitoneal insufflation of carbon dioxide (CO2) may promote collapse of dependent lung regions. The present study was undertaken to study the effects of CO2-pneumoperitoneum (CO2-PP) on atelectasis formation, arterial oxygenation, and arterial to end-tidal Pco2-gradient (Pa-e′CO2). Fifteen anaesthetized pigs [mean body weight 28 (sd 2) kg] were studied. Spiral computed tomography (CT) scans were obtained for analysis of lung tissue density. In Group 1 (n=5) mechanical ventilation (VT=10 ml kg −1, Fio2=0.5) was applied, in Group 2 (n=5) Fio2 was increased for 30 min to 1.0 and in Group 3 (n=5) negative airway pressure was applied for 20 s in order to enhance development of atelectasis. Cardiopulmonary and CT data were obtained before, 10, and 90 min after induction of CO2-PP at an abdominal pressure of 12 mmHg. Before CO2-PP, in Group 1 non-aerated tissue on CT scans was 1 (1)%, in Group 2 3 (2)% (P<0.05, compared with Group 1), and in Group 3 7 (3)% (P<0.05, compared with Group 1 and Group 2). CO2-PP significantly increased atelectasis in all groups. Pao2/Fio2 fell and venous admixture (‘shunt’) increased in proportion to atelectasis during anaesthesia but CO2-PP had a varying effect on Pao2/Fio2 and shunt. Thus, no correlation was seen between atelectasis and Pao2/Fio2 or shunt when all data before and during CO2-PP were pooled. Pa-e′CO2, on the other hand correlated strongly with the amount of atelectasis (r2=0.92). Development of atelectasis during anaesthesia and PP may be estimated by an increased Pa-e′CO2.