The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

UNCUFFED ENDOTRACHEAL TUBES TO SCAVANGE ANESTHETIC EXPOSURE DURING CONTINUOUS ISOFLURANE MECHANICAL VENTILATION, IN THE PICU

Timothy Cox, RRT, Wayne Manning, RRT, Edward Cullen, D.O.; A. I.. DuPont Hospital for Children, Thomas Jefferson Medical College, Wilmington, De.

Introduction: Bronchodilator effects of inhalation anesthetics such as Isoflurane have been reported with improved peak inspiratory pressure and gas exchange. Mechanical ventilation with continuos Isoflurane for support of pediatric patients with reactive airway disease in a intensive care unit requires a closed ventilatory system. In our facility this is accomplished with an Federal Drug Administration (FDA) approved Servo 900C Anesthesia System (Siemens Medical System, Danvers, MA) and a cuffed endotracheal tube (ETT). However, pediatric patients are routinely intubated with uncuffed ETTs. We describe a simple adaptation to uncuffed ETT, to scavenge continuous Isoflurane, and avoid exchange with cuffed ETTs on unstable reactive airway disease patients. Case Summary: CT is a nine month old African American male with a past medical history of mechanical ventilation at birth, and bronchopulmonary dyspalsia. CT was electively intubated, at the sending hospital, for a herniorrhaphy, with an uncuffed 3.5mm ETT and transported to our Pediatric Intensive Care Unit (PICU) for treatment of post-obstructive pulmonary edema, reactive airway disease. He required mechanical ventilation and aggressive management of wheezing with continuous delivery of Isoflurane over a 39-hour period before transitioning to conventional ventilation and subsequent extubation. As CT's airway edema resolved he developed an increased air leak around the uncuffed ETT resulting in a proportional leak of Isoflurane into his room and concern of anesthesia exposure to his assigned health care providers. The use of Isoflurane over 39 hours involved approximately 9 hours on pressure control ventilation (PCV) and 30 hours on volume control ventilation. Tidal volume loss is reported as inhaled vs exhaled minute ventilation (VE) and the patient's normalizing End Tidal Carbon Dioxide (ETCO2) levels support improvement.

Date Time Mode Deliv.Ve** Exhal.Ve** % leak RRset/act % ISOF.
3/11/99 1650 PCV N/A 2.32 N/A 25/25 1
3/12/99 730 SIMV/PSV 3 2.26 25% 25/25 0.9
3/12/99* 1940 SIMV/PSV 3 2.4 20% 25/25 0.3
3/13/99 30 SIMV/PSV 3 2.5 17% 25/25 0.3
3/13/99 400 SIMV/PSV 3 2.1 30% 25/25 0.3
3/13/99 745 SIMV/PSV 3 2 33% 25/25 0.28
* endoscopy mask applied ** liters/min

We employed, unsuccessfully, several pieces of equipment to scavenge the Isoflurane leaking from CT's ETT including a care cube (MES, Burbank, CA) and an adult simple mask (Allegiance, McGaw Park, II). We finally utilized an Endoscopy Mask (VBM Medizintechnik, Sultz, Germany; Thomas Medical, Alpharetta, GA). The masks is available in three sizes, infant, child and adult and features a silicone membrane with a 1mm hole in the center, to facilitate the passage of a Endoscopy scope. We threaded the ETT through this hole. In addition the mask has a 60 mm long flexible hose and 15 mm adapter for the attachment of a ventilator circuit. We attached a 15 mm adapter from a spare ETT to this flexible hose and then to bubble tubing and finally to the wall suction at negative 45cm water pressure. We were careful not to allow the mask to seal around his mouth and nose because of the potential for skin pressure necrosis and to facilitate evacuation of the mask. The lack of appreciable Isoflurane odor by caregivers was immediate. Discussion: Due the unique nature of this situation we were forced to be resourceful in solving the problem of scavenging Isoflurane with uncuffed ETTs. Literature defines massive airway leaks > 10% (Bernstein, Crit. Care Med. 1995:23(10)1739-1744). The use of the continuous deli

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