الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 206 |  |  |
| | | from | 206 | | |
Abstract
Summary
Hypovolemia is a very frequent clinical situation in the intensive care unit (ICU) and is primarily treated with volume expansion. Unfortunately, only 40–70 % of critically ill patients with acute circulatory failure display a significant increase in their cardiac output (CO) in response to volume expansion [1]. In septic shock, fluid infusion is usually recommended [2] but may be harmful particularly in patients with acute respiratory distress syndrome (ARDS) [3, 4]. It is therefore essential to have reliable tools for predicting the efficacy of volume expansion and thus distinguishing patients who might benefit from volume expansion from those in whom the treatment is likely to be inefficient or harmful. [1, 5–7].
Left intraventricular flow obstruction (LVOT) is classically described in asymmetric hypertrophic cardiomyopathy [8] and is characterized by a saber-shaped Doppler flow curve, with late acceleration [9]. The obstruction is usually at the level of the left ventricular outflow tract (LVOT), and is due to systolic anterior movement (SAM) of the anterior leaflet of the mitral valve. This phenomenon has also been previously described in certain clinical situations outside the setting of hypertrophic cardiomyopathy, mainly revolving around hypovolemia and catecholamines exposure [10].
On the other hand, the early phase of septic shock is associated with hypovolemia, hyperkinesia and low left ventricular (LV) afterload (making catecholamines infusion necessary), which may induce Left intraventricular flow obstruction (LVOT) [11]
Mechanical ventilation induces cyclic variations in cardiac preload that are reflected in cyclic changes in aortic blood flow and arterial pulse pressure within the timeframe of a few heart beats. The arterial pulse pressure variation induced by mechanical ventilation has been shown to be useful to discriminate between responder and non-responders patients to volume loading [5, 6, 20].
Researches have also demonstrated that inferior vena cava diameter may predict preload state in intubated, mechanically ventilated patients and in spontaneously breathing patients [14-16]. Inferior vena cava respiratory variability is known to be related to fluid-responsiveness in ICU mechanically ventilated patients and may discriminate between responder patients (i.e., in whom CO increases after fluid infusion≥15%) from non-responders (in whom CO remains at the same level or increases <15%) [17,18]. However, the accuracy of inferior vena cava variations for predicting fluid need in spontaneously breathing patients are scarce.
Our objectives in this study was to detect the prevalence of Hypovolemia in ventilated septic shock patients according to presence of LVOT obstruction and its clinical implications Also to judge the power of prediction of different haemodynamic modalities for assessment of Fluid responsiveness in ventilated septic shock patients e.g. pulse pressure variation, transthoracic echocardiography (through Left intraventricular flow obstruction pattern, IVC diameter variability), and CVP.
This was a prospective study that was carried out on 50 patients with septic shock and on controlled mechanical ventilation who were admitted to the Critical Care Department of the Beni-Suef University Hospital from august 2017 to September 2018
• For volume expansion (VE); all patients were received 500ml normal isotonic saline 0.9% as fluid bolus. It was administered rapidly over 10 minutes. Two sets of hemodynamics measurements were done the first before VE and the second immediately after VE. Cardiac output (CO), stroke volume (SV), IVC distensibility index and left ventricle out flow tract obstruction (LVOT) were measured by transthoracic echocardiography. Respiratory variation of pulse pressure (PPV) and central venous pressure (CVP) were recorded
During the study period, LVOT obstruction was found in 18 patients (36 %). Mortality rate at 28 days was found to be higher in patients with LVOT than in patients without LVOT obstruction (72.2% versus 34.4 %, p < 0.01). Around 89 % of patients with LVOT obstruction were fluid responsiveness versus 62.5% from patient without LVOT obstruction (P-value=0.04).
The results of this study Showed that the most important baseline patient parameters that could predict the fluid responsiveness of patient with septic shock were the PPV% with p-value < 0.001 and AUC= 1.00 The cutoff point was13.5% with sensitivity 100% and specificity 100%. IVC distansability index had p-value < 0.001 and AUC= 0.934 .The cutoff point 16.5% carried a sensitivity 86% and specificity 86 % and CVP was the least predictor with p-value = 0.03 and AUC= 0.264 The cutoff point 6 cmH2o with sensitivity 50%and specificity 30%.