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CVS Monitoring in Shock. CVS Monitoring. Non-invasive techniques: Clinical assessment of tissue perfusion ECG, NiBP, pulse oximetry; Non-invasive CO studies – Echo, NiCO method Invasive Monitoring: Central venous pressure monitoring; Direct arterial line pressure monitoring;
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CVS Monitoring Non-invasive techniques: • Clinical assessment of tissue perfusion • ECG, NiBP, pulse oximetry; • Non-invasive CO studies – Echo, NiCO method Invasive Monitoring: • Central venous pressure monitoring; • Direct arterial line pressure monitoring; • Cardiac Output studies (Pulmonary Artery Catheter)
Central Venous Catheterisation Internal jugular vein Subclavian vein Axillary vein Femoral vein The absolute valueis often unhelpful, except in extreme cases of severe hypovolaemia, significant fluid overload, or heart failure. Correct interpretation requires assessment of the change in central venous pressure in response to a fluid challengein conjunction with alterations in other monitored variables. Other Indications for CVC: Drug delivery (Adrenaline, Noradrenaline, Potassium, other hypertonic solutions), Total Parenteral Nutrition (TPN), etc.
Complications of central catheters • On insertion • Cardiac arrythmias • Pneumothorax / haemothorax • Air embolism • Surrounding tissue injuries • Cardiac tamponade • Post insertion • Infection (consider removal after 7 days) • Cardiac arrhythmias • Displacement of catheter • Blockage of lumen(s) • Air / material embolism • Thrombus formation
Direct arterial pressure monitoring Invasive cannulation of an artery for continuousmonitoring of direct BP; used in: Haemodynamically unstable patient, patient in shock Patient receiving inotropic / vasoactive agents For blood sampling (ABG’s, U&E’S, glucose etc) Patient with physiological difficulties for NIBP (obesity, AF) Stroke volume variation (SVV) : difference between the largest and the smallest arterial wave traces during respiratory cycle
Techniques to assess cardiac output (Flow-based techniques) • Oesophageal Doppler • based on determination of RBC velocity/flow • Trans-oesophageal Echocardiography (TOE) • Gold standard in USA • Arterial pulse/pressure wave analysis (PPWA) • eg PiCCO, Vigileo, LiDCO • Combination of pulse/pressure wave analysis (PPAW) with oesophageal Dopler flow measurement (for re calibration) • Bioimpedance / Bioreactance • Change in amplitude / frequency of a transmitted electrical signal
Pulse contour analysisPPWA If an arterial pressure waveform is calibrated to a known cardiac output then tracking the changed in the shape and size of arterial waveform can give information to the changes in cardiac output.
Pulmonary artery catheterisation • Dr. Jeremy Swan and Dr. William Ganz • Developed 1971 • Catheterisation of the pulmonary artery with a balloon flotation catheter allows to measure: • Preload - indirect assessment of the filling pressure of the left ventricle (pulmonary artery occlusion or wedge pressure) • Contractility – by using ‘thermodilution’ technique • Afterload or SVR - by calculating from the formula SVR = CO / MAP (PAC; PAFC; PAOP; PAWP)