Intraoperative application of high-frequency ventilation

Tomographic Comparison of Ventilation Techniques for CT-Guided Thoracoscopic Staple Excision of Subcentimeter Lung Nodules

This study was planned to compare the computed tomographic detectability of lung nodules in three ventilatory conditions: total lung capacity, high-frequency ventilation, and total lung deflation. In an ex vivo lung model, 44 nodules were simulated. Using computed tomography (CT) scans, nodules were detected and compared to the actual number and excised under CT guidance. Simulated nodules measured 6.2 +/- 2.1 mm and demonstrated an attenuation of 175 +/- 14 HU. Observer confidence was highest at total lung capacity (5.00 +/- 0.00), in comparison to high-frequency ventilation and total lung deflation (4.69 +/- 0.78, 4.94 +/- 0.27, p = .24). The kappa score for total lung capacity, high-frequency ventilation, and total lung deflation was 1.00, 0.96, and 0.98, respectively, indicating a very high interrater reliability. Although surgical devices generated a substantial artifact, 90% of nodules were excised. Thus, although total lung capacity produces the highest confidence level, all three of the ventilatory techniques examined have similar detection of subcentimeter pulmonary nodules using computed tomography scans.

High frequency jet ventilation: use of the Bain system for entrainment

The use of a Bain system to convey anaesthetic gases for entrainment during high frequency jet ventilation (HFJV) was evaluated by examining the effect of varying the fresh gas flow (Vf) on the end-tidal carbon dioxide (PECO2) in 46 ASA physical status I and II patients undergoing extracorporeal shock-wave lithotripsy (ESWL). Anaesthesia was induced with methohexitone (1-2 mg.kg-1), fentanyl (1-1.5 micrograms.kg-1) and vecuronium (0.1 mg.kg-1). After endotracheal intubation with a Mallinckrodt Hi-Lo Jet cuffed endotracheal tube, the patient was immersed in a water bath and HFJV at 150 breaths per minute was instituted with an Acutronic AMS 1000 jet ventilator attached to the side channel of the Hi-Lo tube. A Bain system was attached to the proximal end of the endotracheal tube to provide gases for entrainment. Anaesthesia was maintained with an intravenous infusion of methohexitone (5 mg.kg-1.h-1) and 50% nitrous oxide in oxygen for both the jetted and entrained gases. PECO2 was determined at 5-min intervals by a single-breath technique using a calibrated Engstrom Eliza capnograph. Thirty patients were randomly allocated to receive Vf's of 50 (Group 1), 75 (Group 2) and 100 (Group 3) ml.kg-1.min-1, respectively. A further eight patients (Group 4) received a Vf of 100 ml.kg-1.min-1 for 15 min, 75 ml.kg-1.min-1 for the next 15 min and 50 ml.kg-1.min-1 thereafter. In a further group of eight patients (Group 5), Vf was initially 25 ml.kg-1.min-1 for 10 min and was then switched off for the remainder of the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

High-frequency pulsation (HFP) in a patient with Guillain-Barré syndrome

A patient with Guillain-Barré syndrome (GBS) developed a respiratory crisis despite recurrent treatment with plasma exchange. Thus mechanical ventilatory support became necessary. As an alternative to conventional ventilatory techniques high-frequency pulsation (HFP), a modified high-frequency jet-ventilation technique was used. According to the observations HFP may be a valuable technique for the continuous adaptation to the patient's individual respiratory demands in GBS.

Ventilation and ventilators--an update

In the five years which have passed since the previous review, the literature has been concerned more with the ways in which ventilators may be applied to patients and the effects of differing patterns of ventilation than with the design philosophy of the ventilators themselves. This account should be read in conjunction with that of 1982 [1].