The advent of recent Doppler two-dimensional ultrasound technology has subjugate the need of invasive measurements of several important cardiac parameters.

The advent of recent Doppler two-dimensional ultrasound technology has subjugate the need of invasive measurements of several important cardiac parameters. It allows estimation of preload, contractility, and afterload. Positive end-expiratory squeezing (PEEP) is associated with a reduction in cardiac output The responsible mechanisms are controversial. To evaluate the cardiovascular answers to PEEP, we employed different Doppler hemodynamic indices for the first time, combined with conventional two-dimensional echocardiography. Twenty-one healthy, young, and unsedated offers were admitted to the cogitation Under spontaneous respiration, PEEP flat was increased stepwise (0, 5 75 10 125 cm [Hsub2]O) At each come forth level, the following right and left ventricular parameters were assessed with Doppler two-dimensional echocardiography: two-dimensional variables: end-diastolic contortion indices (EDVI), ejection fraction (EF) and left ventricular afterload-LaPlace relation (combined with strike systolic pressure); Doppler variables: cardiac index (CI) (combined with two-dimensional measure of valve area), maximum velocity (Vmax), time velocity integral (TVI), acceleration time (AT), deceleration time (DT) deceleration rate (DR) ratio of early to atrial peak (E/A), ratio of isovolumic contraction time to ejection time (IVCT/ET), and maximum line acceleration (dv/dt) in aorta and main pulmonary artery. Increasing issue resulted in a proportional decrease in biventricular EDVI. Moreover, issue application is also causing a very little of CI, which is determined from a decrease in Vmax and TVI, while EF IVCT/ET, dv/dt Doppler transatrioventricular parameters, and afterload stay in normal ranges. Employing Doppler hemodynamic indices for the first time in this subject of attention setting clearly supports data that the pendant in EDVI and CI during pip is caused by reduction in ventricular filling fit to decreased venous return. Using the Doppler parameters IVCT/ET and dv/dt changes in myocardial contractility, as well as changes in afterload (LaPlace relation) can be rul out

(Chest 1994; 106:67-73)

AT=acceleration time;

CI=cardiac index;

DR=deceleration rate;

DT=deceleration time;

dv/dt=maximum acceleration of the blood;

E/A=ratio of early to atrial peak;

EDVI=end-diastolic body index;

IVCT/ET=isovolumic contraction time/ejection time;

LV=left ventricle;

PEEP=positive end-expiratory pressure;

RV=right ventricle;

TVI=time velocity integral;

Vmax=maximum velocity

Since the introduction of controll ventilation with positive end-expiratory crushing (PEEP), it has been widely recognized that an increase in intrathoracic influence is associated with a decrease in cardiac output common of the mechanisms behind this is a reduction of venous return(1)(2)(3)(4) in accordance with Starling's law. Other mechanisms remain the make subordinate of considerable debate. It has also been hinted that the reduction in cardiac output may be caused at an increase in right ventricular afterload,(5) reflexly mediated depression of cardiac function with increased systemic afterload,(6) or at altered myocardial metabolism.(7) Furthermore, Jardin et al,(8)(9) using two-dimensional echocardiography during mechanical ventilation with issue demonstrated a decreasing radius of interventricular septum in diastole leading to its leftward shift with impeding filling of the left ventricle. Nevertheless, the investigation of the mechanisms for decrease in cardiac output by means of PEEP application has been limited by way of the methods available to date.

We anticipated that modern Doppler parameters would be real useful for examination of this question The goal of the quick in emergencies study was to investigate the impact of different cheep levels on right and left ventricular function and hemodynamics using precordial two-dimensional echocardiography. Also, for the first time in as it was a setting, we wanted to investigate the Doppler parameters in an attempt to clarify one of the mechanism(s) responsible for the small quantity in cardiac output in healthy, awake volunteers

MATERIAL AND METHODS

After approval at the ethics committee and receiving informed consensus 21 healthy volunteers, 12 men and 7 women aged from 21 to 39 years (mean age, 292) were admitted to the investigation The subjects were instructed to breathe with a tightly attached face mask (Rusch) using a high deliquesce (40 L/min) CPAP system (Drager CF 800) that recorded airway squeezing and tidal volume continuously. Heart rate (beats/min), end-tidal C[Osub2] (mm Hg) and oxygen saturation (mm Hg) were monitored continuously (Siemens-Sirecust 961) relations pressure was recorded with an electronic oscillotonometer (Dinnamap).

All bring under rules could maintain a tidal contortion of 10 to 12 ml/kg at a respiratory rate between 12 and 14/min. Hemodynamic close attention was carried out at basal conditions and after incremental increase of issue levels: 5, 7.5, 10, and 125 cm [Hsub2]O with 15 min between each set-up

Studies were performed at means of an ultrasound scheme (Hewlett-Packard) combining a two-dimensional phased-array sector scanner for imaging with a puls Doppler image analyzer for velocity measurements. This apparatus has a software package for computerizing all investigated parameters. A 25-MHz transducer was used for imaging and velocity recording. Continuous videorecorded images were played back by the and of videocassette system equipment. The frozen images were recorded forward a glossy black and white paper at a spe of 100 mm/ Patients were examined in the left semilateral decubitus position and standard transthoracic echocardiographic planes were used.

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