High Frequency Jet Ventilation in CPR

Klain M, Keszler H, Brader E Critical Care Medicine 1981 Vol 9 Pages 421-422

The authors study high frequency jet ventilation (HFJV) during CPR using a cannula (14-gauge catheter) introduced into the trachea percutaneously or inserted into the end of an endotracheal tube. Small jet pulses of high velocity at a frequency of 100-500/min are used to wash out the alveoli, probably by increasing turbulent flow. To study the application of HFJV for CPR, five series of experiments were performed on a total of 50 dogs. In the first series, gas exchange with HFJV and conventional positive pressure ventilation (IPPV) was compared during recovery from asphyxic hypotension and during CPR in fibrillating hearts in six dogs. Both HFJV and IPPV were equally effective in maintaining gas exchange during CPR after asphyxia (PaO2 354.7 +/- 76.1 torr vs. 269.5 +/- 38.7 torr). After resuscitation, ventricular fibrillation was induced electrically in the same dogs and HFJV-CPR or IPPV-CPR was used with each method alternating every 10 mins. for a total of three 20-minute blocks. No statistically significant differences were found in gas exchange (mean values pH 7.2 vs. 7.24, PaCO2 34 vs. 30 torr, PaO2 96 vs. 134 torr) and common carotid artery blood flow (7.4 +/- 3.4 ml/min vs. 7.8 +/- 3/7 ml/min) between both modalities. In the second series, the effect of HFJV on aspiration was studied in 18 dogs. In half the experiments, transtracheal puncture was performed; in the other half, uncuffed translaryngeal catheters inserted between the vocal cords were used to administer HFJV. The mouth was then filled with stained fluid and the effects of various frequencies and I:E ratio were evaluated. Aspiration did not occur under any type of HFJV provided expiration was no longer than 66% of the cycle or the respiratory rate was less than 60/min. If HFJV was stopped, aspiration occurred almost immediately. Restarting HFJV usually pushed the fluid back up. In the third series, the flow pattern during transtracheal HFJV was followed by radio-cinematography in 10 dogs. A piece of meat was soaked in radio-opaque material and positioned deep in the hypopharynx so it obstructed the airway. By percutaneous puncture and HFJV, the foreign body was dislodged upwards similar to the expected action during the Heimlich maneuver. Radio-opaque liquid was also injected at various levels in the airway. Contrast material in the trachea above the orifice of the jet catheter had a tendency to be expelled into the mouth. Contrast material below the catheter was propelled deeper into the lungs. In the fourth series, cardiac assist was studied in 10 dogs. HFJV was synchronized with heart rate so that the tracheal pressure increase occurred either during systole or diastole. While pulmonary artery pressure was augmented correspondingly, no significant change in cardiac output or mean arterial pressure was found. In the fifth series, administration of cardioactive drugs directly into the jet stream was studied. In two dogs, cardiogreen dye was injected and direct observations by bronchoscopy made of its distribution in the lung. It was found that the nebulized drug was transported by the jet stream to the most distant airways which could be observed. On subsequent autopsy, the dye was found in the most peripheral airways. In the next four dogs, 0.4 mg epinephrine or 0.8 mg atropine was administered and the hemodynamic response observed during HFJV first in animals with intact circulation, and later in two animals after cardiac arrest with cardiac compressions. A similar hemodynamic response was observed to that of IV administration. The authors conclude that it was shown experimentally that HFJV should be considered under certain conditions as the initial step in advanced life support. Simple cricothyroid puncture could probably be used to dislodge a foreign body, for immediate ventilatory support and for intrapulmonary drug administration before an IV route is secured.