The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts


Barry Varner, BS RRT, Critical Care Coordinator, Fawaz Akbik M.D., South Fulton Medical Center, East Point, Ga.

Introduction: There are few reported cases regarding successful application of HFOV in the adult population. In this case study we describe how the Sensormedics 3100A oscillator was used for a 20 year old, 70 kg. female with ARDS secondary to lupus pneumonitis.

Case Summary: A 20 y/o female was admitted via emergency services after a 3 day history of hemoptysis, shortness of breath, hematuria, and left pleuritic chest pain. Chest radiograph revealed left pleural effusion and bibasilar atelectasis. ABG's on 4 L/m: pH 7.42, PaCO_{2} 29 torr, PaO_{2} 80 torr, SaO_{2} 94%. The patient was admitted to the general medical floor with I.V. antibiotics where she deteriorated over the next 9 hours. ABG's on a non-rebreathing mask: pH 7.39, PaCO_{2} 32 torr, PaO_{2} 48 torr. She was subsequently intubated and mechanically ventilated in the assist/control (A/C) mode @V_{t} 800 ml, f12, and FiO_{2} 1.0. PEEP was applied at the lower inflection point which increased from 5 to 12 cm H_{2}O over 36 hours as peak inspiratory pressure (PIP) increased from 35 to 58 cm H_{2}O. ABG's @ V_{t} 800 ml, f22, FiO_{2} 1.0, PEEP 12 cm H_{2}O, mean airway pressure (P_{AW}) = 22 cm H_{2}O: pH 7.43, PaCO_{2} 36 torr, PaO_{2} 60 torr (Oxygenation index [OI] =37, PaO_{2}/FiO_{2} ratio =60). Chest radiograph revealed complete bilateral opacification. HFOV was initiated using the Sensormedics 3100A @: 5 Hz, T_{i} 45%, P_{AW} 30 cm H_{2}O (increased to 35 cm H_{2}O to achieve a SpO2>=90%), amplitude [filled triangle] p 55 cm H_{2}O, FiO_{2} 1.0. Chest radiograph after 1 hour revealed lung expansion at 8.5 posterior ribs with dramatically improved alveolar recruitment. ABG's after 2 hours on HFOV: pH 7.32, PaCO_{2} 51 torr, PaO_{2} 199 torr (OI = 15, PaO_{2}/FiO_{2} ratio = 199). Dopamine infusion @ 5-12 mcg/kg/min. was required for maintenance of systolic blood pressure in the 100-120 torr range. Propofol and atracurium infusions were necessary to facilitate toleration of HFOV which was maintained for 7 days. ABG's were within acceptable limits and hemodynamic status was relatively stable. On day 7 the patient developed subcutaneous emphysema with a small amount of mediastinal air on chest radiograph. HFOV settings: 4 Hz, T_{i} 49%, P_{AW} 25, amplitude [filled triangle] p 53 cm H_{2}O, FiO_{2} 0.6. ABG's: pH 7.29, PaCO_{2} 36 torr, PaO_{2} 62 torr (OI =24, PaO_{2}/FiO_{2} ratio =103). In view of overall improvement in chest radioigraph, OI, and hemodynamic status the patient was transitioned to conventional mechanical ventilation in the A/C mode @ V_{t} 700 ml (PIP 38 cm H_{2}O), f20, FiO_{2} 0.7, PEEP 10 cm H_{2}O, P_{AW} 19 cm H_{2}O. Chest radiograph after 1 hour revealed lung expansion at the 9th posterior rib with a notable decrease in mediastinal air. Subcutaneous emphysema dissipated significantly over the next 4 hours. Atracurium and propofol infusions were weaned and withdrawn as conventional ventilation was maintained over 7 days with incrementally improving pulmonary mechanics. Ventilator mode was changed to SIMV with pressure support on day 12. Weaning of mechanical ventilation was accomplished successfully and the patient was extubated on ventilator day 16. She was transferred to the general medical floor on day 21 with O_{2} by nasal cannula @ 3 L/m, and discharged home on day 27 with no functional deficit.

Discussion: HFOV is yet to be well established in the adult critical care arena, however, depletion of conventional ventilation options may perpetuate lung injury and consume valuable time. Due to rapid deterioration of gas exchange and progression of pulmonary infiltrates, gentle ventilation in the form of HFOV was considered to be the best option for this patient. Literature exists in the form of a pilot study supporting the use of HFOV for adult patients with ARDS. This case provides additional clinical evidence in support of pilot study data.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.