Haemodynamics and oxygenation improvement induced by high frequency percussive ventilation in a patient with hypoxia following cardiac surgery: a case report

<p>Abstract</p> <p>Introduction</p> <p>High frequency percussive ventilation is a ventilatory technique that delivers small bursts of high flow respiratory gas into the lungs at high rates. It is classified as a pneumatically powered, pressure-regulated, time-cycled, high-frequency flow interrupter modality of ventilation. High frequency percussive ventilation improves the arterial partial pressure of oxygen with the same positive end expiratory pressure and fractional inspiratory oxygen level as conventional ventilation using a minor mean airway pressure in an open circuit. It reduces the barotraumatic events in a hypoxic patient who has low lung-compliance. To the best of our knowledge, there have been no papers published about this ventilation modality in patients with severe hypoxaemia after cardiac surgery.</p> <p>Case presentation</p> <p>A 75-year-old Caucasian man with an ejection fraction of 27 percent, developed a lung infection with severe hypoxaemia [partial pressure of oxygen/fractional inspiratory oxygen of 90] ten days after cardiac surgery. Conventional ventilation did not improve the gas exchange. He was treated with high frequency percussive ventilation for 12 hours with a low conventional respiratory rate (five per minute). His cardiac output and systemic and pulmonary pressures were monitored.</p> <p>Compared to conventional ventilation, high frequency percussive ventilation gives an improvement of the partial pressure of oxygen from 90 to 190 mmHg with the same fractional inspiratory oxygen and positive end expiratory pressure level. His right ventricular stroke work index was lowered from 19 to seven g-m/m²/beat; his pulmonary vascular resistance index from 267 to 190 dynes•seconds/cm⁵/m²; left ventricular stroke work index from 28 to 16 gm-m/m²/beat; and his pulmonary arterial wedge pressure was lowered from 32 to 24 mmHg with a lower mean airway pressure compared to conventional ventilation. His cardiac index (2.7 L/min/m²) and ejection fraction (27 percent) did not change.</p> <p>Conclusion</p> <p>Although the high frequency percussive ventilation was started ten days after the conventional ventilation, it still improved the gas exchange. The reduction of right ventricular stroke work index, left ventricular stroke work index, pulmonary vascular resistance index and pulmonary arterial wedge pressure is directly related to the lower respiratory mean airway pressure and the consequent afterload reduction.</p

Continuous right ventricular end-diastolic volume in comparison with left ventricular end-diastolic area

Background and objective Intraoperative management of patients with end-stage liver disease undergoing liver transplantation requires fluid administration to increase cardiac output and oxygen delivery to the tissues. Filling pressures have been widely shown to correlate poorly with changes in cardiac output in the critically ill patient. Continuous right ventricular end-diastolic volume index (cRVEDVI) and left ventricular end-diastolic area index (LVEDAI) monitoring have been increasingly used for preload assessment. The aim of this study was to compare cRVEDVI, LVEDAI, central venous pressure and pulmonary artery occlusion pressure with respect to stroke volume index (SVI) during liver transplantation. Methods Measurements were made in 20 patients at four predefined steps during liver transplantation. Univariate and multivariate panel-data fixed effect regression models (across phases of the surgical procedure) were fitted to assess associations between SVI and cRVEDVI, pulmonary artery occlusion pressure, central venous pressure and LVEDAI after adjusting for ejection fraction (categorized as ≤ 30, 31-40, &gt;40). Results SVI was associated with continuous right ventricular ejection fraction. The model showing the best fit to the data was that including cRVEDVI: even after adjusting for continuous right ventricular ejection fraction and phase, the regression coefficient of cRVEDVI in predicting SVI was statistically significant and indicated an increase in SVI of 0.21 ml m-2 for each increase of 1 ml m-2. At the multivariate analysis, an increase in LVEDAI of 1 cm m-2 led to an increase in SVI of 1.47 ml m -2 (P = 0.054). Conclusion cRVEDVI and LVEDAI gave a better reflection of preload than filling pressure, even if only cRVEDVI reached statistical significance. © 2009 European Society of Anaesthesiology

Epicardial real-time three-dimensional echocardiography in cardiac surgery: A preliminary experience

Purpose. Intraoperative two-dimensional transesophageal echocardiography (2DTEE) is a widely accepted method to guide cardiac valve surgery. The aim of our study was to evaluate the feasibility, effectiveness, and incremental value of intraoperative epicardial real-time three-dimensional echocardiography (RT3DE). Description. Thirty consecutive patients (18 aortic and 12 mitral valve diseases) underwent intraoperative 2DTEE and RT3DE before and after cardiopulmonary bypass. Five observers compared independently 2DTEE to live and full volume images and to the surgical view, to assess the incremental value of RT3DE in depicting the different anatomic structures. Evaluation. Epicardial RT3DE was feasible in all patients. Qualitative evaluation determined RT3DE superiority in depicting aortic cusp morphologic lesions; left ventricular outflow tract spatial relationships with mitral apparatus and aortic root; and both anterior and posterior mitral leaflet scallops, particularly posterior commissure. Conclusions. In our study, epicardial RT3DE has been demonstrated to improve morphologic definition of anatomic valvular lesions and their relationship with cardiac adjacent structures. It may be a valid substitute when the 2DTEE approach is contraindicated, or it could have a complementary role, coupled with 2DTEE, to give additional information for surgical planning