HAEMODYNAMIC MONITORING( IABP, CVP, CO ) Al jadidiSulaiman Moderator: DrNikAzman
Haemodynamic monitoring.. • It is the measurement of haemodynamic status • Haemodynamic status is an index of pressure & flow within cardiovascular system – pulmonary & systemic circulations
Introduction • Haemodynamic measurement are important to establish – precise diagnosis - determine appropriate therapy - monitor response to therapy • Extent of monitoring depends on how much data is required to optimisept’s condition, & how precisely data is to be recorded
Purpose of monitoring.. • Early detection, identification, and treatment of life-threatening conditions such as heart failure and cardiac tamponade • Evaluate the patient’s immediate response to treatment such as drugs and mechanical support • Evaluate the effectiveness of cardiovascular function such as cardiac output and index
Rationale for haemodynamic monitoring • Previous experience using similar monitoring technique was shown to be beneficial • Next level – understanding the pathophysiology of process being treated, such as heart failure or hypovolemic shock
Indication (1)Diagnostic • causes of patient’s pathophysiological condition (2)Therapeutic • base on the index & clinical situation, specific therapy & treatments are prescribed (3)Research • assess efficacy of new therapy
Any deficit or loss of cardiac function: such as AMI,CHF,Cardiomyopathy • All types of shock;cardiogenic,neurogenic,oranaphylactic • Decreased urine output from dehydration, hemorrhage,G.I. bleed,burns,or surgery
Type of monitoring.. Invasive • Arterial pressure monitoring • Central venous pressure monitoring • Pulmonary artery pressure monitoring • cardiac output • pulse contour cardiac output Non-invasive • ECG • Non-invasive blood pressure • Pulse oximetry • Tissue perfusion • temperature • mentation • Urine output • Echocardiogram & Doppler
Invasive pressure monitor • Access to an artery or vein • catheter connected to fluid filled pressure tubing & pressure transducer • connected to bedside monitor • continuous & accurate • fluctuation: positional • calibration drift • leveling • different sites
Calibration of equipment • For accurate Haemodynamic pressure readings, two baseline measurements are necessary: 1. Calibration of the system to atmospheric pressure 2. Determination of the phlebostatic axis for transducer height placement
Zeroing the equipment • To zero the equipment, turn 3-way stopcock open to air (atmospheric pressure), close to patient and flush system. The monitor is adjusted so that “0” is displayed, which equals atmospheric pressure. • Return the stopcock to original position to visualize the waveform and haemodynamic pressures. • zero once every 8 hours.
Phlebostatic Axis • Left atrium - reference point on the chest • Used as a baseline for consistent transducer height placement. • Obtaining the axis involves drawing a line from the fourth intercostal space, where it joins the sternum, to a mid-axillary line. • The intersection of these lines approximates the level of the atria.
Leveling.. • The transducer air-reference stopcock is leveled with this reference point to obtain accurate patient haemodynamic pressure.
Arterial Pressure Monitoring • Cannulation of an artery & attaching the catheter to a fluid-filled transducer system • Continuous assessment of arterial perfusion to the major organ systems of the body.
Indication • Direct arterial blood pressure monitoring enables accurate continuous pressure measurement. • Allow easy blood sampling for acid-base and other measurements.
Arterial Line Insertion And Sites • Usually the radial artery cannulation is used. • Other most common sites are dorsalispedis, brachial, femoral arteries. • Allen’s test should be performed before a catheter is inserted into the radial artery to ensure the presence of adequate collateral circulation to the hand by the ulnar artery.
Allen’s Test • Both the ulnar and radial arteries are occluded. • Ask the patient to clench and unclench the fist until the hand is blanched. • Release pressure on the ulnar artery only and observe for color return to the hand.
Allen’s Test • If colour returns within 5-7 seconds, the ulnar circulation is adequate. • Ulnar circulation is considered inadequate if the hand remains blanched for longer than 15 seconds. The radial artery should not be cannulated.
Arterial Line Insertion And Sites • Insertion should be performed under sterile technique. • The connecting tubing should be assembled and flushed and the transducer zeroed and calibrated before the catheter is inserted. • Secured the catheter once it is in place.
Normal Arterial Waveform A normal arterial waveform should has 3 components: • a rapid upstroke – systole • a clear dicrotic notch – closure of aortic valve • a definite end-diastole
Arterial pressure.. • Direct intra-arterial measurement may overestimate systolic pressure dt systolic overshoot • This is result of fluid-pressure transducer monitoring system • Can be overcome by ↑ damping of system ( ie by using smaller gauge cannula-transducer tubing)
However, ↑ damping reduces the resonant frequency, thus the sensitivity of the sytem. • >30Hz for HR up to 180bpm >20Hz for HR up to 120bpm • The tubing should be non-compliant & < 1 m in length
Derived variables.. • Rough approx of SV, therefore CO can be obtained from area under systolic pressure curve • However, correlation with CO assessed by thermodilution is poor, & the method is not sufficiently reliable for clinical decision-making
Systolic time intervals are an indirect index of ventricular contractility • Pre ejection period (PEP) = interval from ventricular electrical activity (Q wave) ejection of blood from ventricle. • It consists of electromechanical delay btw the AP & initiation of ventricular contraction, and the isovolumetric contraction • PEP is inversely proportional to ventricular activity
Adequacy of preload.. • The variation in arterial pressure is exaggerated in the presence of reduced preload • Significant correlation has been demonstrated between the systolic arterial pressure variation & end-diastolic area estimated with TOE.
Complication • Ischaemia distal to cannula -major sequalaea/w low CO, shock, sepsis, prolonged cannulation, vasculitis & hyperlipidaemia • Exsanguination -flow thru 18G cannula can cause blood loss of 500ml/min • spurious result • Infection • Intra-arterial injection of drug
The morbidity associated with arterial cannulation is less than that associated with 5 or more arterial punctures!!
Nursing responsibilities • Prevention of blood loss • Prevention of local obstruction • prevention of air embolism • Prevention of sepsis • Accuracies
Troubleshooting.. Damped Waveforms • Pressure bag inflated to 300 mmHg • Reposition extremity or patient • Verify appropriate scale • Flush or aspirate line • Check or replace module or cable
Central Venous Pressure Monitoring • Directly reflects RA pressure • Indirectly reflects the preload of the right ventricle(RV) or RV end-diastolic pressure. • Determined by the interaction of venous tone, central venous volume (blood returning to the heart), and the pumping ability of the heart
Central Venous Pressure • CVP is measured in the superior vena cava or the RA. • Normal ranges 4 – 12 cmH2O
Common sites • Internal jugular vein • Subclavian vein • Brachial vein • Femoral vein
Position • The head is placed in a dependent position (Trendelenburg), which causes the internal jugular vein to become more prominent, facilitating line placement.
Catheter Placement • A long intravenous catheter is inserted into the large veins of the upper thorax (subclavian or internal jugular) are most frequently used for percutaneous CVP line insertion.
Catheter Placement • Threaded into position in the vena cava close to the right atrium. • Correct placement confirmed by observing pressure change with respiration, aspirating blood freely thru catheter & CXR.
Indication • Measurement of central venous pressure • Measurement of central venous oxygenation • Parenteral nutrition • Administration of vasoactive and inotropic agents • As a venous access when all IV sites have been exhausted
CVP is used as guide to right ventricular filling • However, right ventricular preload is determined by EDV (not pressure) hence • Isolated CVP reading is of limited value without knowledge of ventricular compliance • Compliance varies from patient to patient, & with time in the same patient • Thus dynamic changes in CVP are more useful than absolute values.