Jet Ventilation for Fiberoptic Bronchoscopy

An 18-yr-old male underwent cardiopulmonary resuscitation after arrhythmia complicating acute myocarditis. After 3 days of ventilatory support, he was extubated successfully and was discharged subsequently. Six weeks later, he was referred to our university hospital. At the time of presentation, he exhibited respiratory distress with inspiratory and expiratory stridor. Rigid bronchoscopy revealed severe tracheal stenosis just below the cricoid cartilage. Electrocoagulation and dilatation were performed, and the patient was able to breathe spontaneously and comfortably after the procedure. A spiral computed tomography scan 2 days later showed the stenosis to extend 40 mm from its proximal origin, 30 mm below the vocal cords, with an ID of 7.4–8.2 mm.

One week after this admission, tracheal resection was performed. A tracheal segment of 45 mm in length was resected, followed by end-to-end suture. The length of resection rendered head extension impossible. As per our protocol, the patient was extubated immediately after surgery and was transferred subsequently to the surgical intensive care unit. After an initial stable course, on the first postoperative day, he had a substantial decrease in peripheral oxygen saturation (Spo²) to 81%. Chest radiography showed complete atelectasis of the left lung. We elected to perform fiberoptic bronchoscopy during general anesthesia with manual ventilation via  face mask.

After induction of anesthesia by titration of propofol up to a dose of 2.5 mg/kg, we initially verified that manual ventilation via  face mask was feasible. We then commenced an infusion of propofol at the usual dose of 9 mg · kg⁻¹· h⁻¹(i.e. , 150 μg · kg⁻¹· min⁻¹). Topical lidocaine was applied to the larynx via  the instrument channel of the FFB, and it proved unnecessary to administer muscle relaxants. The FFB passed easily through the tracheal anastomosis to the tracheal bifurcation, and no signs of recent bleeding were noted. A thick, white mucous plug was identified, situated 1 cm below the orifice of the left main bronchus. We instilled a mucolytic preparation and commenced suction clearance of the plug and other secretions.

Unfortunately, the mucous proved extremely tenacious, and the procedure was complicated by recurrent decreases in Spo²to unacceptable levels. It proved necessary to repeatedly interrupt fiberoptic bronchoscopy to reestablish more effective manual ventilation. After repeated interruptions and ongoing recurrent desaturations, we decided to use jet ventilation.

We used the Paravent PAT^Eventilator (Elmet Ltd., Přelouč, Czech Republic). This device features a high-powered jet nozzle and incorporates a Venturi principle to enhance administered gas volume. We connected the jet to the suction channel (2.2 mm diameter) of the FFB (Olympus BF 20D, Tokyo, Japan). We then ventilated with pure oxygen using a low-frequency regime at a respiratory rate of 20 breaths/min and a driving pressure of 80 kPa (600 mmHg or 12 psi). Inspiratory to expiratory time ratio was set at 1:1. The tip of the FFB was placed 1–2 cm above the carina.

Using this approach, we were able to achieve Spo²levels higher than 95%, and it proved possible to continue the procedure in a controlled and safe fashion. Chest excursion could be easily observed clinically, and, at the end of the procedure, chest excursions were symmetrical. When Spo²decreased to 90%, we interrupted suction and repeated the jet ventilation maneuver. For vigorous bronchial toilet and to encourage mobilization of secretions, the patient underwent ventilation for a brief period (three times for 1 or 2 min) using a high-frequency mode with a respiratory rate of 180 breaths/min. Finally, we awakened the patient, and the subsequent chest radiography clearly documented successful treatment with reexpansion of the left lung.

This case highlights two particular difficulties that may be faced in the management of pulmonary atelectasis after tracheal reconstruction. First, extreme flexion of the neck presents substantial difficulties for securing a stable airway during an anesthetic procedure. In addition, there is the potential for direct damage to the tracheal anastomoses from any tracheal instrumentation, particularly from blindly placed endotracheal tubes.

The optimum technique for airway management was the subject of much deliberation in this case. Extreme forward tilting of the head prevented insertion of a laryngeal mask airway 2or an endotracheal tube via  a traditional intubation technique. In addition, the possibility of direct tracheal suture injury, even with careful insertion of the endotracheal tube, was of great concern. Finally, we opted for the combination of intravenous anesthesia and manual ventilation via  face mask as described.

There is very limited information in the literature about the use of the instrument (“suction”) channel of the FFB for jet ventilation. In 1980, Satyanarayana et al.  3evaluated this technique in animals and in eight adult volunteers scheduled to undergo minor surgery. He observed excellent arterial oxygenation and hypocarbia and reported no complications. Dalens et al.  4reported a series of 49 pediatric patients with respiratory distress, aged 3 days to 3 yr, who underwent bronchoscopic examination using a similar technique. As in our report, after every distal exploration, the FFB tip was withdrawn to above the carina to ensure bilateral pulmonary insufflations, which were then given for 15 s at a respiratory rate of 50 to 60 breaths/min. Gas exchange was acceptable, and no complications were observed.

In the latest report, Baraka 5applied a similar technique in a 2-yr-old child who was scheduled for bronchoscopy because of atelectasis and pneumonic infiltrates. Unfortunately, the pediatric bronchoscope (3.4 mm OD) could not pass easily through a 4-mm endotracheal tube. He tried to perform the procedure via  a size 2 laryngeal mask airway (7.0 mm ID), which was technically feasible, but low lung compliance made mechanical ventilation difficult, and, after a decrease in Spo²to 85%, intermittent jet ventilation of oxygen via  the instrument channel ensured adequate oxygenation.

These latter two reports imply that the technique can be used safely even in patients with ventilatory compromise. 4,5Although they involved children, we believe that the principles involved may be equally applicable in certain situations in the adult.

One of the obvious risks of this approach is the potential for inadvertently causing barotrauma if the tip of the FFB slips beyond the carina and “wedges” in a bronchus. The added advantage of jetting via  the instrument channel of the FFB is that the position of the jet source can be directly controlled visually, thus enhancing the safety of the procedure. Excessive hyperinflation must be avoided also, and effective exhalation must be ensured. The FFB OD is 5.8 mm, whereas the narrowest lumen diameter of the normal tracheal segments was measured by computed tomography as 15 mm. Therefore, difficulties with exhalation are more likely to originate at laryngeal or upper airway level and can be minimized by ensuring a clear airway. If gas trapping is still a feature, it is easily recognized clinically and can be managed simply by intermittent interruption of jet ventilation.

Another risk, albeit theoretical, that should be considered is the possibility of direct damage to the FFB. The instrument channel in this type of FFB is a polytetrafluoroethylene tube and is unlikely to be damaged if it remains patent. In addition, the risk that the channel could be blocked so tightly that it could lead to a rupture is negligible.

Although the indications for jet ventilation via  the instrument channel of an FFB may be rare, they are more likely to be applicable in a challenging situation and particularly in the presence of a difficult airway management problem. In this case report, the technique greatly facilitated the therapeutic procedure and enhanced its safety. In addition, it decreased the risk of inadvertent tracheal trauma caused by the need for frequent removal and reinsertion of the FFB when applying face mask ventilation.

The authors thank Brian F. Keogh, M.D., F.R.C.A., Consultant Cardiothoracic Anaesthetist, The Royal Brompton Hospital, London, United Kingdom, for his most useful comments and assistance in preparing the manuscript.