2006 OPEN FORUM Abstracts
Use of Esophageal Balloon to Measure Chest Wall Compliance in a Morbidly Obese Patient
Marie Duggan, RRT, Kelan Tantisira, MD, MPH, Paul
Nuccio, RRT, FAARC, Michael Jackson RRT-NPS, CPFT
The patient is a 71 year old male with Type II diabetes, hypertension and morbid obesity (157kg). He was found unresponsive at home. The patient was intubated in the field and transported to our hospital.
Cardiac catheterization revealed inferior septal hypokinesis, 2 vessel CAD with a 90% LAD lesion, a reduced EF and cardiogenic shock CXR revealed bilateral infiltrates.
Upon arrival to the CCU the patient was placed on mechanical ventilation settings, A/C VT 650cc, f 20, FIO2 100%, 17cm PEEP. The patients SaO2 was 94%, PaO2 was 67. Peak inspiratory pressure was 38. Plateau pressure was 33. Over the course of the next 4 days the patient remained severely hypoxemic and experienced several episodes of desaturation into the low 80s. Due to his morbid obesity and his failure to improve his oxygenation despite high levels of FIO2 and PEEP, (PaO2 67 on FIO2 1.0, 18cm PEEP, PaO2 69 on FIO2 .7, 22cm PEEP) the decision was made to place an esophageal balloon. Measuring the transpulmonary pressure would allow the ascertainment of the contribution of his chest wall pressures to his total respiratory system compliance and the optimization of ventilatory pressures.
Measurement was obtained by placing an esophageal balloon (Ackrad Labs Adult) which was inflated with 1 ml of air. Then pressure was monitored using the Ventrak Respiratory Monitoring System connected to a notebook computer. An inspiratory hold was set on our PB840 ventilator to facilitate assessment of compliance.
Our data indicated that at 17cm H2O PEEP the Pair (total airway pressure) was 36cm H2O, the Peso (esophageal pressure) was 33cm H2O at end inhalation and 28cmH2O at end exhalation (see figure 1.). Thus, the calculated alveolar (Pair-Peso) pressure was +4cm H2O at end inspiration and -14cm H2O at end exhalation respectively. This suggested that the alveoli were seeing a negative pressure at end exhalation, thereby experiencing collapse and little distending pressure during inspiration. These likely were both contributing to the persistent hypoxemia and episodes of desaturation. As a therapeutic intervention, the patient was initially placed in reverse trendelenburg; this was of minimal benefit. Subsequently, a recruitment maneuver was done at 30cm H2O, which increased the Pair-Peso from -14cm H2O to 3cm H2O. The patient's saturation improved with the recruitment maneuver, increasing from 90% to 98%. The PEEP was then maintained at 28cmH2O. The patient no longer experienced episodes of desaturation and over the next two weeks was successfully weaned from the ventilator.
Esophageal balloon placement is a minimally invasive procedure used to measure total respiratory compliance. This information produces pertinent clinical data, which is useful in the ventilatory management of the morbidly obese patient. These patients often require higher levels of peep to overcome the decrease in compliance related to the chest wall. Esophageal balloon placement provides the data to determine the optimal ventilatory settings required to overcome the chest wall resistance, resulting in decreasing episodes of alveolar collapse and improved ventilation.