INTRATHORACIC AND PULMONARY BLOOD-VOLUME DURING CO2-PNEUMOPERITONEUM IN HUMANS

Background: Induction of CO2-pneumoperitoneum may have significant eff ects on systemic and pulmonary haemodynamics. We hypothesized, that in trathoracic (ITBV) and pulmonary blood volume (PBV) are affected durin g intra-abdominal CO2-insufflation, which may be pronounced by positio nal changes of the patient. Methods: Sixteen anaesthetized patients we re studied before, during and after CO2-pneumoperitoneum for laparosco pic cholecystectomy. A dye indicator technique was used to assess ITBV and PBV. In addition, gas exchange and haemodynamics were recorded. R esults: In the supine position, induction of CO2-pneumoperitoneum had no effects on ITBV, PBV and cardiac output. Mean systemic arterial pre ssure increased from 10.9+/-1.5 kPa (82+/-11 mmHg) to 12.7+/-1.5 kPa ( 95+/-11 mmHg, P<0.01). In the reverse Trendelenburg position ITBV decr eased from 19.8+/-5.1 ml.kg(-1) to 16.7+/-3.7 ml.kg(-1) (P<0.05) durin g CO2-insufflation, but increased to control values after 20 min. PBV decreased from 4.2+/-1.2 ml.kg(-1) to 3.4+/-1.1 ml.kg(-1) (P<0.05) and remained decreased during CO2-pneumoperitoneum. Calculated venous adm ixture was unchanged throughout the study. Deflation of CO2-pneumoperi toneum increased ITBV (22.4+/-5.2 ml.kg(-1) P<0.05) and cardiac output above control values. Conclusions: In anaesthetized-paralyzed patient s in the reverse Trendelenburg position intra-abdominal CO2-insufflaii on is associated with significant alterations of ITBV and PBV. The rel ease of CO2-pneumoperitoneum is associated with a re-distribution of b lood into the thorax.