Tracheal Gas Insufflation-Aided Mechanical Ventilation during Carbon Dioxide-Induced Pneumoperitoneum in Rabbits

Abstract

ABSTRACT. Despite numerous benefits of laparoscopic procedures, the serious hypercapnia and respiratory acidosis in hypercapnic patients with decreased pulmonary compliance during carbon dioxide-induced pneumoperitoneum (CDP) may be developed. Tracheal gas insufflation (TGI) has been shown to be a useful adjunct to controlled mechanical hypoventilation. This study was undertaken to identify whether TGI superimposed on controlled mechanical ventilation (CMV) improve ventilatory efficiency during CDP in rabbits. Sixteen paralyzed and anesthetized rabbits were used. The animals were assigned to two groups-CMV group: CMV alone; TGI group: CMV superimposed by TGI with flow rate of 2L/min. The animals were insufflated to intra-abdominal pressure of 8 mmHg with CO 2 gas. Then, tidal volume (V T ) was changed to maintain the set peak inspiratory pressure (PIP) value, while other ventilatory settings were kept constant. The set PIP value corresponding to 30, 60, and 90 min after the start of peritoneal insufflation of CO 2 were 15, 22, and 25 cmH 2 O, respectively. During CDP with TGI, PaCO 2 decreased significantly (p<0.01) from CMV without TGI of 82.1 ± 14.1 to 47.5 ± 5.5, 58.1 ± 9.9 to 40.0 ± 4.6, 47.1 ± 9.4 to 32.7 ± 5.1 mmHg at PIP of 15, 22, and 25 cmH 2 O, respectively. The inspired V T decreased significantly (p<0.05) from CMV without TGI of 18.4 ± 3.9 to 12.8 ± 2.8 ml at PIP of 15 cmH 2 O. TGI superimposed on CMV is more effective than CMV alone in enhancing ventilatory efficiency during CDP in rabbits. KEY WORDS: anesthesia, gas insufflation, hypercapnia.J. Vet. Med. Sci. 65(8): 907-912, 2003 Laparoscopic procedures, including laparoscopic diagnosis, appendectomy, cholecystectomy, liver biopsy, hypertrophic pyloric stenosis, splenectomy, and adhesive intestinal obstruction are being performed increasingly in neonates and children [3,25]. Rabbits have been reported as appropriate training models with which to practice the skills needed for laparoscopic surgery in neonates or infants due to their size and abdominal anatomy [11,19,20].Although laparoscopic procedures appear to be associated with a low operative mortality rate through small incision and reduced operative dissection, the serious hypercapnia and respiratory acidosis may develop during carbon dioxide-induced pneumoperitoneum (CDP) [6,9,24]. The ensuing respiratory acidosis induced by hypercapnia can contribute to arrhythmias and even cardiovascular collapse. These risks resulted from CDP may be higher in neonates and infants than in adults and older children.Hyperventilation through increment of ventilatory rate and/or tidal volume in hypercapnic patients during CDP has been routinely recommended as a ventilatory maneuver [6]. However, ventilatory failure in infants with rapid and shallow ventilatory pattern or patients with preexisting cardiopulmonary disease may not be readily corrected by conventional adjustments of minute ventilation. Also, hyperventilation using conventional mechanical ventilation (CMV) in hypercapnic patients with decreased l...

Insuflação de gás traqueal como recurso terapêutico em ventilação mecânica invasiva: revisão sistemática

“…Ambos mecanismos provocam a diminuição do espaço morto através do seu preenchimento com fluxo turbulento de gás na traqueia durante todo o ciclo ventilatório, promovendo e facilitando a troca gasosa adequada. A configuração do sistema de liberação mantido na TGI, com pressões inspiratórias e expiratórias constantes, ocorre porque a válvula de exalação foi ativada durante a fase de inspiração, e o fluxo da TGI foi dirigido para a abertura da via aérea 9,[14][15][16][17] . A avaliação para escolha da utilização da técnica de TGI deve ser direcionada a casos específicos e aplicada corretamente para diferenciar a TGI de todas as demais formas convencionais de manobras com VMI.…”