Chest
Clinical Investigations in Critical CareHemodynamics During PEEP Ventilation in Patients with Severe Left Ventricular Failure Studied by Transesophageal Echocardiography
Section snippets
PATIENTS AND METHODS
The investigation was carried out in 16 patients divided into two groups according to cardiac function. Group A (n = 5) had normal cardiopulmonary function requiring ventilation for treatment of decreased central ventilatory drive or neuromuscular function (Table 1), and group B (n= 11) had severe left ventricular failure requiring ventilation after myocardial infarction with resuscitation (Table 2). Clinical and hemodynamic subsets were assigned according to the classification of Forrester et
RESULTS
Hemodynamic and echocardiographic results are shown in Tables 4 and 5. Figures 2A to 2C show the cross-sectional area and diameters of the left atrium and ventricle and the right ventricle in the long axis view. Examination of the heart after application of PEEP 16 cm H2O showed an acute decrease in right ventricular area and the septal lateral diameter and a displacement of the ventricular septum to the right. The left ventricular area decreased only slightly without marked change in
DISCUSSION
Echocardiography is a practical semi-invasive technique for evaluation of heart morphology and performance. The diagnostic value of the standard precordial technique is limited by thoracic deformation, obesity, emphysema, or after thoracic surgery in 20 percent to 30 percent of patients, particularly during mechanical ventilation. By contrast, the TEE transducer can be easily placed behind the heart and enables continuous evaluation of all four chambers without hindrance from lung
CONCLUSION
PEEP leads to a decrease in cardiac index, a right shift of the ventricular septum, and ventricular interdependence in the acute phase directly after application or discontinuation of PEEP These findings are primarily caused by a reduction of the right atrial and ventricular filling volume by external compression with unchanged transmural filling pressure and left ventricular contractility.
PEEP may be useful not only because of the ability to increase FRC and arterial oxygen content, but also
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This paper includes a part of the Inaugural Dissertation of Wenyan Lu.
Manuscript received May 12; revision accepted May 23.