After we obtained approval from the local supervisory authority and obtained the patients' informed consent, 30 adults (age >18 years, weight <120 kg) admitted for intra- or transbronchial biopsy guided by endobronchial ultrasound, cryotherapy, bronchial lavage, hemostyptic therapy, resection or excision of tumors, or diagnostic bronchoscopy were studied. Pulmonary function analysis was performed before the intervention to determine lung volumes, flow rates, airway resistance, and arterial blood gas tensions (PaO2, PaCO2). Oral premedication consisted of 7.5 mg midazolam administered 1 hour before the endoscopic procedure. Anesthesia was administered using a 1 μg · kg−1 remifentanil bolus (maximum dose limit 100 μg), a 0.25 μg · kg−1 · min−1 infusion, a 2 mg · kg−1 propofol bolus, and a 50 to 70 μg · kg−1 · min−1 propofol infusion. Muscle relaxants were not given. After facemask ventilation, a size 4 or 5 LMA was inserted and its airtight seal was tested. The Veres adapter was connected to the proximal end of the LMA. With an additional flexible metal arm clamped to one side of the operating table, the Veres adapter was locked into position. HFJV was provided by a Twinstream® jet ventilator (Carl Reiner Corp.) as described previously.8 Two jet streams, one at LF and one at HF, were applied simultaneously via 2 separate injectors integrated into the adapter's wall (Fig. 3). LF and HF were set to 12 min−1 and 200 min−1, driving pressures at 0.7 to 1.5 bar according to lung and thoracic rigidity, and inspiratory to expiratory time ratios at 1:1 and 1:1.5. Fraction of inspired oxygen was set to 1.0. The electrocardiogram and noninvasive arterial blood pressure were recorded. The effects of ventilation were assessed by observation of chest movement, continuous monitoring of peripheral oxygen saturation (SpO2), and transcutaneous carbon dioxide tension (PtcCO2) (TCM 40; Radiometer Corp., Copenhagen, Denmark). Ventilation was considered adequate when PtcCO2 was kept within a range of ±10% of the baseline value determined before induction of anesthesia. To increase or decrease minute ventilation, the driving pressure of the LF jet stream was increased or decreased. Bronchoscopy was performed using flexible fiberscopes (Olympus BF 1T180, outside diameter 6 mm, or Olympus BF XP160F, outside diameter 5.5 mm, Olympus Corp., Tokyo, Japan). Lidocaine 1% solution was administered at a total dose of 300 mg in a volume of 30 mL to cover the surface of the trachea and bronchi for topical anesthesia. Excess solution was removed by suction via the endoscope. An additional 40-μg remifentanil bolus was given IV when systolic blood pressure increased 10% above baseline. At the end of the procedure, the administration of drugs was terminated and jet ventilation was continued until spontaneous ventilation resumed and the LMA was removed. Chest radiographs were obtained postoperatively in patients who underwent biopsy. Values are presented as means ± SD unless noted otherwise. The correlation between airway pressure and body mass index was calculated using Prism 5 (GraphPad®, La Jolla, CA).
Patient Characteristics and Baseline Pulmonary Function
Thirty consecutive adults scheduled for diagnostic or therapeutic flexible fiberoptic bronchoscopy were studied. Patient characteristics are shown in Table 1. Indications for the procedure included bronchial carcinoma (57%), sarcoidosis (13%), and other lung diseases (30%).
The median duration of jet ventilation was 22 minutes (range 10–84 minutes). In 5 patients (17%), the duration of endoscopy exceeded 1 hour. PtcCO2 recorded after 10 minutes of jet ventilation was 45.3 ± 8.2 mm Hg. One patient presented with an SpO2 of 86% preoperatively, which increased instantly during HFJV to 95%. SpO2 was 97% ± 2% after 10 minutes of HFJV. Average driving pressures of the HF and LF jet streams were 1.03 ± 0.19 bar and 1.07 ± 0.16 bar, respectively. In 3 patients, the rate of the LF ventilation increased from 12 min−1 to a maximum of 20 min−1 to keep PtcCO2 values at baseline values. Figure 4 shows upper airway pressures. All patients remained hemodynamically stable (mean arterial blood pressure 77.8 ± 17.0 mm Hg). SpO2 decreased below 90% in 4 patients for a few minutes during bronchial lavage, and there was a deliberate reduction of fraction of inspired oxygen to 0.21. One patient developed a pneumothorax after peripheral biopsy. One patient had an increased peak airway pressure (28 cm H2O), and 1 patient required continuous positive airway pressure mask ventilation in the postoperative care unit to improve oxygenation.
Our results demonstrate that the Veres adapter may be a valuable tool to deliver jet ventilation to patients undergoing interventional or diagnostic fiberoptic bronchoscopy. Access for flexible bronchoscopy can be by the LMA in anesthetized patients. Future studies are needed to determine whether procedure times are reduced and anesthesia recovery is faster with this new device. In contrast to conventional respirators, jet ventilators deliver gas when airways are partially obstructed by instruments. HFJV has been used in rigid and flexible bronchoscopy.3,9,10 Tidal volumes were injected via small-bore catheters placed in channels or via side ports of bronchoscopes. The use of an LMA improves access, especially when a high tracheal stenosis is treated.11,12 The combined use of HFJV with an LMA has also been reported.13 Although the Swivel adapter provided access for various instruments or jet lines, HFJV is delivered more effectively via the Veres integrated injectors. The Veres facilitates jet ventilation independent of the bronchoscope's position and can be used for simultaneous application of 2 jet streams, which is more effective than single-jet ventilation.7 The airway will be less compromised by the combined use of the Veres adapter and the LMA than with an endotracheal tube. The introduction of a bronchoscope with an external diameter of 6 mm will lead to a 56% reduction in the cross-sectional area of a conventional tracheal tube (ID 8 mm). It will lead to only a 16% reduction in the Veres adapter (ID 15 mm) and a 27% reduction in an LMA (ID 11.5 mm). Limitations of this combined technique include incorrect positioning of the LMA,14 the physical properties of HF ventilation,1,15 and the application of high-pressure gas.16 Gastric insufflation due to gas leakage into the esophagus and damage to laryngeal structures are well known but rare and minor complications associated with the use of the LMA. The risk of gas insufflation into the stomach under our study conditions would result from incomplete sealing of the airway with the LMA.
We thank the technicians at Carl Reiner Corp., Vienna, Austria, especially Dominik Lirsch, for the technical advice and assistance in the development and production of the Veres adapter.
1. Ihra G, Gockner G, Kashanipour A, Aloy A. High-frequency jet ventilation in European and North American institutions: developments and clinical practice. Eur J Anaesthesiol 2000; 17:418–30
2. Sanders RD. Two ventilating attachments for bronchoscopes. Delaware Med J 1967;30:170–5
3. Carden E, Trapp WG, Oulton J. A new and simple method for ventilating patients undergoing bronchoscopy. Anesthesiology 1970;33:454–8
4. Brimacombe J, Tucker P, Simons S. The laryngeal mask airway for awake diagnostic bronchoscopy: a retrospective study of 200 consecutive patients. Eur J Anaesthesiol 1995;12:357–61
5. Verghese C, Brimacombe JR. Survey of laryngeal mask airway usage in 11,914 patients: safety and efficacy for conventional and nonconventional usage. Anesth Analg 1996;82:129–33
6. Naguib ML, Streetman DS, Clifton S, Nasr SZ. Use of laryngeal mask airway in flexible bronchoscopy in infants and children. Pediatr Pulmonol 2005;39:56–63
7. Bacher A, Lang T, Weber J, Aloy A. Respiratory efficacy of subglottic low-frequency, subglottic combined-frequency, and supraglottic combined-frequency jet ventilation during microlaryngeal surgery. Anesth Analg 2000;91:1506–12
8. Ihra G, Hieber C, Schabernig C, Kraincuk P, Adel S, Plöchl W, Aloy A. Supralaryngeal tubeless combined high-frequency jet ventilation for laser surgery of the larynx and the trachea. Br J Anaesth 1999;83:940–2
9. Sivarajan M, Stoler E, Kil HK, Bishop MJ. Jet ventilation using fiberoptic bronchoscopes. Anesth Analg 1995;80:384–7
10. Hautmann H, Gamarra F, Henke M, Diehm S, Huber RM. High frequency jet ventilation in interventional fiberoptic bronchoscopy. Anesth Analg 2000;90:1436–40
11. Adelsmayr E, Keller C, Erd G, Brimacombe J. The laryngeal mask and high-frequency jet ventilation for resection of high tracheal stenosis. Anesth Analg 1998;86:907–8
12. Biro P, Hegi TR, Weder W, Spahn DR. Laryngeal mask airway and high-frequency jet ventilation for the resection of a high-grade upper tracheal stenosis. J Clin Anesth 2001;13:141–3
13. Canty DJ, Dhara SS. High frequency jet ventilation through a supraglottic airway device: a case series of patients undergoing extracorporeal shock wave lithotripsy. Anaesthesia 2009;64: 1295–8
14. Latorre F, Eberle B, Weiler N, Mienert R, Stanek A, Goedecke R, Heinrichs W. Laryngeal mask airway position and the risk of gastric insufflation. Anesth Analg 1998;86:867–71
15. Ihra G, Tsai C, Kimberger O. Intrinsic PEEP at various frequencies of supraglottic jet ventilation in a model of dynamic upper airway obstruction. Anesth Analg 2010;111:703–6
© 2011 International Anesthesia Research Society
16. Cook TM, Alexander R. Major complications during anaesthesia for elective laryngeal surgery in the UK: a national survey of the use of high-pressure source ventilation. Br J Anaesth 2008;101:266–72