Optimizing working space in porcine laparoscopy: CT measurement of the effects of intra-abdominal pressure
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Several factors may affect volume and dimensions of the working space in laparoscopic surgery. The precise impact of these factors has not been well studied. In a porcine model, we used computed tomographic (CT) scanning for measuring working space volume and distances. In a first series of experiments, we studied the relationship between intra-abdominal pressure (IAP) and working space.
Eleven 20 kg pigs were studied under standardized anesthesia and volume-controlled ventilation. Cardiorespiratory parameters were monitored continuously, and blood gas samples were taken at different IAP levels. Respiratory rate was increased when ETCO2 exceeded 7 kPa. Breath-hold CT scans were made at IAP levels of 0, 5, 10, and 15 mmHg. Insufflator volumes were compared to CT-measured volumes. Maximum dimensions of pneumoperitoneum were measured on reconstructed CT images.
Respiratory rate had to be increased in three animals. Mild hypercapnia and acidosis occurred at 15 mmHg IAP. Peak inspiratory pressure rose significantly at 10 and 15 mmHg. CT-measured volume increased relatively by 93 % from 5 to 10 mmHg IAP and by 19 % from 10 to 15 mmHg IAP. Comparing CT volumes to insufflator volumes gave a bias of 76 mL. The limits of agreement were −0.31 to +0.47, a range of 790 mL. The internal anteroposterior diameter increased by 18 % by increasing IAP from 5 to 10 mmHg and by 5 % by increasing IAP from 10 to 15 mmHg. At 15 mmHg, the total relative increase of the pubis–diaphragm distance was only 6 %. Abdominal width did not increase.
CT allows for precise calculation of the actual CO2 pneumoperitoneum volume, whereas the volume of CO2 released by the insufflator does not. Increasing IAP up to 10 mmHg achieved most gain in volume and in internal anteroposterior diameter. At an IAP of 10 mmHg, higher peak inspiratory pressure was significantly elevated.
KeywordsAnimal model CO2 Computed tomography Laparoscopy Pneumoperitoneum Working space
We thank P. Specht for assistance in the experiments and M. Dijkshoorn for CT scanning.
John Vlot, Rene Wijnen, Robert Jan Stolker, and Klaas Bax have no conflicts of interest or financial ties to disclose.
- 6.Neudecker J, Sauerland S, Neugebauer E, Bergamaschi R, Bonjer HJ, Cuschieri A, Fuchs KH, Jacobi Ch, Jansen FW, Koivusalo AM, Lacy A, McMahon MJ, Millat B, Schwenk W (2002) The European association for endoscopic surgery clinical practice guideline on the pneumoperitoneum for laparoscopic surgery. Surg Endosc 16(7):1121–1143PubMedCrossRefGoogle Scholar
- 18.Balick-Weber CC, Nicolas P, Hedreville-Montout M, Blanchet P, Stéphan F (2007) Respiratory and haemodynamic effects of volume-controlled vs pressure-controlled ventilation during laparoscopy: a cross-over study with echocardiographic assessment. Br J Anaesth 99(3):429–435PubMedCrossRefGoogle Scholar
- 19.Gurusamy KS, Samraj K, Davidson BR (2009) Low pressure versus standard pressure pneumoperitoneum in laparoscopic cholecystectomy. Cochrane Database Syst Rev (2), Art. No. CD006930. doi: 10.1002/14651858.CD006930.pub2
- 23.Ahmad G, O’Flynn H, Duffy JMN, Phillips K, Watson A (2012) Laparoscopic entry techniques. Cochrane Database Syst Rev (2), Art. No. CD006583. doi: 10.1002/14651858.CD006583.pub3
- 27.Fung YC (1993) Biomechanics: mechanical properties of living tissues, 2nd edn. Springer, New YorkGoogle Scholar
- 30.Berne RM, Levy MN (1988) Physiology, 2nd edn. Mosby, St. LouisGoogle Scholar