2005 OPEN FORUM Abstracts
OXYGEN Insufflation Catheter Placement During Apnea Testing Parul Shah, RRT. Thomas Malinowski, RRT, FAARC. Inova Fairfax Hospital, Falls Church, VA.
The standard procedure for providing supplemental oxygen during apnea testing incorporates the placement of an oxygen insufflation catheter down the endotracheal tube to the level of the carina 1,2. We report a complication of this methodology while performing an Apnea test to establish Brain death.
Case Presentation: A 39 year old female with a 2-day history of headaches was found unconscious at home. The patient had no pre-existing lung disease. On admission to the emergency room the patient was orally intubated with a 7 mm endotracheal tube and placed on mechanical ventilation. On neurologic exam, the right pupil was fixed and dilated and left pupil nonreactive to light stimulus. Head CT revealed ruptured colloid cyst with intracerebral hemorrhage. Subsequent neurologic exam showed absent higher cognitive functioning or brain stem reflexes. The patient was mechanically ventilated with a ventilator rate of 14 BPM, VT 450 ml., FiO2 .30, PEEP 5 cmH2O with ABG: pH 7.5, pCO2 24, PaO2 157, Bicarb 19, BE -3. On hospital day 3 the decision to establish brain death and the withdrawal of support was made upon the wishes of the family. Ventilator settings were altered to normalize PaCO2. The endotracheal tube placement was confirmed radiographically at 6.5cm above the carina. The patient was removed from the ventilator, a 14 French Ballard T double swivel suction catheter with length markings was inserted into the endotracheal tube so the tip was 1 centimeter below the tip of the endotracheal tube. Six (6) liters per minute of oxygen was administered via the catheter. Within 30 seconds, patient developed visible subcutaneous emphysema starting at the upper neck and progressing to Right upper chest. The apnea test was stopped the catheter removed, and the patient placed back on pretest vent settings. The patient experienced ventricular fibrillation, and required CPR. Bilateral chest tubes were placed. The patient was successfully resuscitated. The CXR revealed right sided pnemothorax, free air within pericardium, mediastinum, and subcutaneous spaces. The family decided to withdraw the support, patient expired and autopsy was not performed.
Discussion: The sustained continuous flow of oxygen via catheter located at the tip of the carina is a common approach used to insure adequate alveolar oxygenation during apnea testing. We have used this technique without complication on multiple cases. The technique is described by the Quality Standards Subcommittee of the American Academy of Neurology and is commonly referenced in articles describing apnea testing and brain death. We observed a rapid and significant case of pulmonary barotrauma with this approach. Neither the oxygen flowrate used (6 LPM) nor the catheter-to-endotracheal tube diameter (< 50%) should have resulted in significant air-trapping or auto-PEEP effect. Insufflating gases delivered via catheter directly from a flowmeter are capable of reaching 50 psig (3500 cm H2O). We attribute the barotrauma to the insufflation catheter being distal to the endotracheal tube tip, possibly impinging against the carina or tracheal wall. We present this case to alert other practitioners to the potential hazards of catheter placement.
1.Summary statement from Quality Standards Subcommittee, Neurology 1995; 45: 1012-14,
2. Wijdicks FM, The diagnosis of Brain Death, NEJM: 2001; 344 (16) 1215-21