[Comparative study of high-frequency jet ventilation in 4 types of patients undergoing laryngeal microsurgery]

To study high frequency jet ventilation (HFJV) in patients with chronic obstructive pulmonary disease (COPD) who are obese or who have tracheal or laryngeal stenosis, conditions which are often found in patients undergoing microsurgery of the larynx (MSL), comparing the results with those for a group of controls, patients with no stenosis who were also undergoing MSL.

Eighty patients were distributed in four groups as follows: those meeting the criteria for a diagnosis of COPD (n = 20), those who were overweight (n = 24), those with stenosis over 50% of the laryngeal opening (stenosis group, n = 10) and those with no associated pathology (control group, n = 26). HFJV was administered through a 2.2 mm internal diameter orotracheal injection catheter, using an Ergojet CVT (Temel, S.A.). The ventilatory protocol was as follows: rate 100 breaths/min, inspiratory time 30%, generator pressure (GP) 2.2 to 3.3 kg/cm2 and FiO2 70% to 90%. We analyzed the GP administered, jet volume (Vjet) delivered, maximum (PAWmax) and minimum (PAWmin) airway pressures, oxygen hemoglobin saturation (SpO2), partial pressures of O2 (pO2) and CO2 (pCO2) in arterial blood, and end-tidal pressure of CO2 (PETCO2) at baseline and 10 and 20 min after the start of HFJV. Because monitoring was invasive, the study was designed for a small series of patients and we believe it should not be generalized to include all patients undergoing MSL under normal conditions.

HFJV had to be abandoned and conventional ventilation used in 4 patients (2 in the COPD group and 2 in the obese group). Ventilation was judged adequate in the remaining patients, with the observations that in the COPD group, pO2 levels were lower than in the control group at the 10 min readings and pCO2 levels were higher at both the 10 and 20 min readings. PAW levels were higher throughout the procedure in both the COPD and stenosis groups. In the obese patients, pCO2 was higher at both the 10 and 20 min recordings.

HFJV provides effective ventilation for most patients undergoing MSL, even if they are obese or have COPD or laryngeal stenosis.