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Transpulmonary pressure evaluation in an obese patient under mechanical ventilation
Critical Care volume 12, Article number: P320 (2008)
It is often difficult to manage optimal ventilation parameter settings in patients with low chest wall compliance, as in an obese patient. This case report demonstrates options to ventilate such difficult patients.
A 34-year-old obese woman was transferred to our academic ICU to solve difficult ventilation and oxygenation problems in the context of septic shock following urinary tract infection. This patient was transferred to an Avea ventilator (Viasys Healthcare) and an 8 Fr esophageal balloon catheter was inserted in the lower third of the esophagus. An expiratory airway occlusion maneuver, described by Baydur and colleagues , was performed to confirm correct positioning. We performed an inspiratory hold to obtain and compare the airway plateau pressure (Pplat) and transpulmonary plateau pressure (Ptpplateau), and an end-expiratory hold to obtain and compare airway total positive end-expiratory pressure (PEEPt) and transpulmonary total PEEP (PtpPEEP). Transpulmonary pressures were used to change ventilator parameter settings.
The patient had a BMI of 58.6. Arterial blood gas showed metabolic and respiratory acidosis (pH: 7.18, paCO2: 53, HCO3: 19) and hypoxemia (paO2: 75, SpO2: 94% with 1.0 FiO2) that persisted for 4 days prior to the installation of an esophageal balloon. The Pplat was 52.6 cmH2O and PEEPt was 24.8 cmH2O, with a set PEEP of 8 cmH2O. The Ptpplateau was 14.3 cmH2O and PtpPEEP was -4.4 cmH2O. The set PEEP was increased to 25 cmH2O, which resulted in a PtpPEEP of -1.4 cmH2O. Hemodynamic parameters remained unchanged. Within 24 hours, FiO2 was decreased down to 0.35 (pH: 7.34, paCO2: 35, HCO3: 18, paO2: 165, SpO2: 99%), and the patient was extubated 3 days later.
As demonstrated in acute lung injury patients , this case study also showed a clinical benefit of measuring transpulmonary pressures to adjust ventilator parameter settings, especially the PEEP to recruit the lung, as it should be observed in patients with very abnormal chest wall compliance.
Baydur A, Behrakis PK, Zin WA, et al: Am Rev Respir Dis. 1982, 126: 788-791.
Talmor D, Sarge T, O'Donnell CR, et al: Crit Care Med. 2006, 34: 1389-1394. 10.1097/01.CCM.0000215515.49001.A2.
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Delisle, S., Francoeur, M. & Albert, M. Transpulmonary pressure evaluation in an obese patient under mechanical ventilation. Crit Care 12, P320 (2008). https://doi.org/10.1186/cc6541
- Plateau Pressure
- Transpulmonary Pressure
- Chest Wall Compliance
- Esophageal Balloon
- Acute Lung Injury Patient