Combined Pressure Control/High Frequency Ventilation in Adult Respiratory Distress Syndrome and Sickle Cell Anemia: Results
Throughout the period of mechanical ventilation (both conventional and HFV), oxygen saturation was maintained greater than 90 percent, red blood cell transfusions were used to help maintain an adequate oxygen content, and the blood pressure was supported such that the patient did not suffer hypotension or lactic acidosis natural asthma treatment.
After 5 days on the PVDV, a repeated chest radiograph (Fig 3) revealed improvement. Since uncuffed endotracheal tubes are recommended for patients treated with the PVDV to facilitate removal of airway secretions, and the use of pressure control ventilation in a patient with an uncuffed endotracheal tube during weaning is associated with large changes in tidal volumes as the patient awakens and moves, he was again given conventional ventilation in a volume-limited mode (synchronized intermittent mandatory ventilation: SIMV; Siemens-Elema Servoventilator 900C) to facilitate more vigorous weaning.
He was extubated 4 days later and was discharged home 18 days after hospital admission. Chest radiograph at 1 month (Fig 4) showed resolution of the majority of the infiltrates and the patient was asymptomatic. The concept of combined mode ventilation is not new. Pressure support and SIMV have been used frequently in combination. More recent strategies have combined several types of HFV; others have combined intermittent mandatory ventilation (IMV) with high-frequency oscillatory ventilation (HFOV).
The combined mode ventilatory approach used by the PVDV has also been described as “high-frequency flow interruption.” The high frequency and pressure control ventilatory components can be configured independently according to the desired strategy. A background pressure control respiratory cycle (inspiratory and expiratory times in seconds) may be superimposed on subtidal, high-frequency breaths (inspiratory and expiratory time in milliseconds).
Figure 3. Chest radiograph after 5 days of therapy with the PVDV, shows improvement.
Figure 4. Chest radiograph 1 month after discharge from hospital, shows clearing of most infiltrates and air leaks, though some residual interstitial markings remain.
Category: Respiratory Symptoms
Tags: barotrauma, high frequency ventilation, sickle cell anemia