Videoendoscopic endotracheal intubation in the rat: a comprehensive rodent model of laparoscopic surgery.
BACKGROUND
Peritoneal absorption of CO(2) during abdominal insufflation in laparoscopy may disrupt the acid-base equilibrium and alter the physiological response to stress. Current nonventilated rodent models of laparoscopy do not manage the CO(2) load of pneumoperitoneum, but ventilated surgical rodent models are invasive (tracheotomy) and may independently induce the inflammatory response.


METHODS
A comprehensive rodent model of laparoscopy was developed. Rats were randomized to receive anesthesia alone, anesthesia plus CO(2) pneumoperitoneum, or anesthesia plus CO(2) pneumoperitoneum with videoendoscopic intubation and mechanical ventilation. Arterial blood-gas analysis was performed at baseline and after 30 min of intervention.


RESULTS
Baseline pH, pCO(2), and HCO(3)(-) arterial blood gas parameters were normal for all rats. After 30 min, pCO(2) and pH changed slightly but remained normal among rats receiving anesthesia alone (pCO(2) = 46.5 +/- 1.9; pH = 7.365 +/- 0.009) whereas animals receiving anesthesia plus CO(2) pneumoperitoneum that were dependent on spontaneous respiration for ventilation developed significant hypercarbic acidosis (pCO(2) = 53.2 +/- 1.9, P < 0.05; pH = 7.299 +/- 0.011, P < 0.001). This acidosis was completely corrected with increased minute ventilation in intubated rats receiving mechanical ventilation (pCO(2) = 36.8 +/- 1.5, P < 0.001; pH = 7.398 +/- 0.011, P < 0.001).


CONCLUSIONS
CO(2) pneumoperitoneum induces significant hypercarbic acidosis in nonventilated rats. Noninvasive endotracheal intubation is feasible in the rat with videoendoscopic assistance. Our noninvasive rodent model of laparoscopic surgery controls for anesthesia- and capnoperitoneum-related acid-base changes and provides an environment in which the biological response to pneumoperitoneum can be studied precisely.
Fuentes
Joseph M
JM
Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Hanly
Eric J
EJ
Bachman
Sharon L
SL
Aurora
Alexander R
AR
Marohn
Michael R
MR
Talamini
Mark A
MA
D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000209:etiology / Q000517:prevention & control; D000758:Anesthesia; D000818:Animals; D002245:Carbon Dioxide; D004724:Endoscopy; D005240:Feasibility Studies; D007442:Intubation, Intratracheal; D010535:Laparoscopy; D008297:Male; D023421:Models, Animal; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial; D013690:Television
D002245:Carbon Dioxide