Haemodynamic monitoring-1.pptx ytfjjjjbjn
- 4. Q1 Are the factors that influence CVP too numerous to make it meaningful?
- 5. INVASIVE BLOOD PRESSURE MONITORING
- 6. INDICATION Indications: • Rapid moment to moment BP changes • Frequent blood sampling • Circulatory therapies: bypass, vasoactive drugs, deliberate hypotension • Failure of indirect BP: burns, morbid obesity • Pulse contour analysis
- 7. Contraindications • Absence of collateral flow • Raynaud's disease and cold infusions • Angiopathy, coagulopathy (recent anti-coag. or thrombolytic infusion increases risk of hematoma and compressive neuropathy), atherosclerosis: Use Caution! • Avoid locating near A-V fistula, and inserting through synthetic graft • Diabetics at increased risk of complications • Avoid local infection, burn or traumatic sites • Avoid extremities with carpal tunnel syndrome
- 8. Radial Artery cannulation Various techniques: • Direct cannulation • Transfixation • Seldinger’s technique • Doppler assisted • 2-D USG assisted • Surgical cutdown
- 9. Radial Artery Cannulation • Technically easy • Good collateral circulation of hand • Complications uncommon except: Bleeding,hematoma,local vasosapsm, Repeated punctures, infection
- 10. Perform Modified Allen test
- 12. Alternative Sites FEMORAL ARTERY – • Largest artery commonly selected for monitoring BP • Risk of distal ischemia after femoral art. cannulation is reduced owing to large diameter of artery • Atherosclerotic plaque embolization is more likely during initial guidewire and catheter placement. • Seldinger’s technique • Puncture below inguinal ligament
- 13. AXILLARY ARTERY • The axillary artery provide for long-term pressure monitoring • Advantages Patient comfort, mobility, and access to a central arterial pressure waveform. • Complications Similar in incidence to radial and femoral artery catheterization. • If the axillary approach is chosen, the left side is preferred over the right because the axillary catheter tip will lie distal to the aortic arch and great vessels. • Risk of cerebral embolization is increased whenever more centrally located arterial catheters are used
- 14. Technical Aspects of Direct Blood Pressure Measurement • Pressure signal is influenced significantly by measuring system, including arterial catheter, extension tubing, stopcocks, flush devices, transducer, amplifier, and recorder. • Underdamped, second-order dynamic systems. • Fluid-filled systems - mass-spring systems that demonstrate simple harmonic motion and exhibit similar behavior that depends on the 1.physical properties of elasticity, 2. mass, and 3. friction
- 15. 3 properties determine system's operating characteristics- frequency response or dynamic response, which in turn are characterized by 2 imp. system parameters 1. natural frequency (fn, ω) and 2. damping coefficient (ζ, Z, α, D) Natural frequency of monitoring system quantifies how rapidly system oscillates Damping coefficient quantifies frictional forces that act on system and determine how rapidly it comes to rest
- 16. • Arterial BP- waveform periodic complex wave • Fourier analysis. • Original pressure wave has characteristic periodicity termed fundamental frequency, which is equal to HR. • HR is reported in bpm • Fundamental frequency is reported in cycles per second or hertz (Hz).
- 17. Fourier analysis
- 18. • 6 to 10 harmonics are required to provide distortion-free reproduction of most arterial pressure waveforms. • Accurate blood pressure measurement in a patient with a PR of 120 bpm (2 cycles/sec or 2 Hz) requires monitoring system dynamic response of 12 to 20 Hz. • The faster the HR and the steeper the systolic pressure upstroke, the greater the dynamic response demands on monitoring system.
- 19. • Most catheter-transducer systems are underdamped but have an acceptable natural frequency that exceeds 12 Hz. • If system's natural frequency is lower than 7.5 Hz, the pressure waveform is often distorted, and no amount of damping adjustment can restore monitored waveform to resemble original waveform. • If natural frequency can be increased sufficiently (e.g., 24 Hz), damping will have minimal effect on monitored waveform, and faithful reproduction of intravascular pressure is achieved
- 23. INFERENCE • Pressure monitoring system will have optimal dynamic response if its natural frequency is as high as possible. • Best achieved by using short lengths of stiff pressure tubing and limiting the number of stopcocks and other monitoring system appliances. • Blood clots and air bubbles trapped and concealed in stopcocks and other connection points will have similar adverse influences on the system's dynamic response
- 24. Components of Pressure Monitoring Systems • Intra-arterial catheter • Tubing, • Stopcocks, • In-line blood sampling set, • Pressure transducer, • Continuous-flush device, and • Electronic cable connecting the bedside monitor and waveform display screen.
- 25. • Stopcocks in system provide sites for blood sampling and allow transducer to be exposed to atmospheric pressure to establish a zero reference value. • Blood sampling ports and in-line aspiration systems permit drawing of blood without use of sharp needles and .
- 26. FLUSHING SYSTEM • Flush device provides continuous, slow (1 to 3 mL/hr) infusion of saline to purge monitoring system and prevent thrombus formation within arterial catheter. • Dextrose solutions should not be used because flush contamination of sampled blood may cause serious errors in blood glucose measurement. • A dilute concentration of heparin (1 to 2 units heparin/mL saline) has been added to the flush solution to further reduce the incidence of catheter thrombosis, but this practice increases the risk for heparin- induced thrombocytopenia and should be avoided.
- 30. Transducer Setup: Zeroing and Leveling • The transducer is set to zero reference—ambient atmospheric pressure—against which all intravascular pressures are measured. • This process underscores the fact that all pressures displayed on the monitor are referenced to atmospheric pressure outside the body.
- 32. • Adjustment of arterial transducer level to a diff. position on body. It is critically important to recognize that when this is done, the pressure is being measured at the level of transducer and not at level of the aortic root. • e.g. during sitting neurosurgical operations, if arterial pressure transducer is raised to a level even with the patient's ear to approximate the location of the circle of Willis, the clinician is measuring blood pressure at the level of the brain and must recognize that aortic root pressure is higher (by an amount equal to vertical difference in ht. between pressure transducer and aortic root).
- 33. • . Raising height of bed relative to transducer will cause overestimation of BP • whereas lowering patient below transducer will cause underestimation BP.
- 36. 1st shoulder (the Inotropic Component): early systole, opening of aortic valve, transfer of energy from contracting LV to aorta 2nd shoulder (the Volume Displacement Component): produced by continuous ejection of stroke volume from LV, displacement of blood, and distention of the arterial wall Diastole: when the rate of peripheral runoff exceeds volume input to the arterial circulation
- 37. Possible Information gained from a pressure waveform • Systolic, diastolic, and mean pressure • Myocardial contractility (dP/dt) • Peripheral vascular resistance (slope of diastolic runoff) • Stroke volume (area under the pulse pressure curve) • Cardiac output (SV x HR)
- 38. As BP is measured farther into periphery: • Pressure waveforms recorded simultaneously from diff arterial sites will have different morphologies because of physical characteristics of vascular tree, namely, impedance and harmonic resonance • The anacrotic and dicrotic notches disappear • The waveform appears narrower • The systolic and pulse pressure increase • The upstroke becomes steeper • The diastolic and mean pressure decrease
- 40. Distal pulse wave amplification of the arterial pressure waveform. When compared with pressure in the aortic arch, the more peripherally recorded femoral artery pressure waveform demonstrates a wider pulse pressure (compare 1 and 2); a delayed upstroke (3); a delayed, slurred dicrotic notch (compare arrows); and a more prominent diastolic wave.
- 69. • Made of poly vinyl chloride • OD 5 – 7 & 110 cm long pliable shaft that softens at body temperature Thermister •4 cm from the tip •Detects Bl temp changes for calculation of CO Proximal lumen (Rt Atrial lumen) Ends 30 cm from the tip Measures CVP Distal lumen (pulm artery lumen) Ends at the tip Measures Pulm artery pressure and PCWP Balloon is 12mm from the tip. Wedges catheter for measuring PCWP Balloon inflation port with 1.5 ml lock syringe Special accessories 1. Pacemaker channel end 14 cm from catheter tip for temporary pace maker insertion. 2. Rapid response thermistor measuring EF of Rt ventricle 3. Oximetric catheter optical hookup continuous monitoring of mixed venous O2 saturation 4. Thermal filament located near the tip continuous measurement of CO
- 70. Pulmonary Artery Catheterization • Continuous pressure monitoring during PAC insertion is required to determine location of the catheter tip. • Inflate the balloon when the 20cm mark is at the hub of the introducer. • Advance the PAC until the pulmonary capillary wedge pressure (PCWP) is obtained, usually around 45-55cm at the hub.
- 72. Indications For PAP & PCWP Monitoring Cardiac surgery: i) Poor LV function (EF<0.4; LVEDP> 18 mm Hg) ii) Recent MI iii) Complications of MI eg. MR, VSD, ventricular aneurysm. iv) Combined lesions eg. CAD+MR or CAD+AS v) IABP Non-cardiac situations: i) Shock of any cause ii) Severe pulmonary disease iii) Complicated surgical procedure iv) Massive trauma v) Hepatic transplantation vi)Ventilator management>determining the best PEEP
- 73. • Contraindications • Absolute • Tricuspid or Pulmonary valve stenosis • RA or RV masses • Tetralogy of Fallot • Relative • Severe arrhythmias • Coagulopathy • Newly inserted pacemaker wires
- 74. TEMPORAL ASSOCIATION WITH OTHER EVENTS
- 82. PiCCO
- 119. GDFT
- 121. Monitoring IV Volume Status Static parameters • BP • HR • Urine output • CVP • Mixed venous oxygen saturation Dynamic parameters • Indices based on respiratory variation (Arterial pressure waveforms) - PPV, SVV, SPV or changes in IVC diameter • PVI • Aortic blood flow • SV estimation - Esophageal doppler/ arterial waveform analysis • Passive leg raising • End expiratory occlusion test • LV size estimation - TEE
- 122. Monitoring IV Volume Status- Static parameters BP and HR • Not predictable in individual patients • Healthy young patient with subclinical hypovolemia has normal HR and BP because of stress response of surgery which activated SNS and RAS • Patient on Beta Blockers - not manifest tachycardia in response to hypovolemia
- 123. Monitoring IV Volume Status- Static parameters Urine Output • Oligouira < 0.5 ml/kg/hr - Indication of hypovolemia • However anaesthesia and surgical stress can decrease urine output • If patient is euvolemic and administration of fluid is done to treat oligouria - Fluid Overload • Traditional targets of 0.5 ml/kg/hr are not warranted • But sustained oligouria < 0.3 ml/kg/hr - increase risk of renal injury
- 124. Monitoring IV Volume Status CVP and Pulmonary artery occlusion pressure Inaccurate surrogates • To determine cardiac preload • Poor predictors of fluid responsiveness • Do not detect/predict impending pulmonary edema indicative of hypervolemia
- 125. Monitoring IV Volume Status- Static parameters Mixed Venous Oxygen Saturation SVO2 • Propotional to Cardiac output, tissue perfusion and tissue oxygen delivery • Inversely propotional to tissue oxygen consumption • Do not reflect changes in tissue perfusion during perioperative period when oxygen consumption varies
- 126. Monitoring IV Volume Status- Dynamic parameters Indices based on respiratory variation • Pulse pressure variation • Stroke volume variation • Systolic pressure variation • Changes in IVC diameter Can be observed or measured to assess responses to fluid challenges
- 127. Monitoring IV Volume Status- Dynamic parameters Inspiration - Increases Intrathoracic pressure Decreases Venous return Decrease RV filling volume Decrease RV and LV stroke volume
- 128. Monitoring IV Volume Status- Dynamic parameters Expiration - Decreases Intrathoracic pressure Increases Venous return Increase RV filling volume Increase RV and LV stroke volume
- 129. Monitoring IV Volume Status- Dynamic parameters • Changes in Venous return - Lead to variation in stroke volume, pulse pressure and SBP • Normal respiratory variations < 10 % • Greater variation - Fluid responsiveness • Need to administer fluids
- 130. Copyrights apply
- 131. Copyrights apply
- 132. Monitoring IV Volume Status- Dynamic parameters Not useful • Open chest procedures • MV with low TV < 8 ml/kg or high PEEP > 15 cm H2O • Elevated intraabdominal pressures • Cardiac arrythmias • RV failure • Requirement for vasomotor infusions
- 133. Monitoring IV Volume Status- Dynamic parameters IVC diameter • Cyclical changes in IVC diameter measured by Echocardiograhy - Predict fluid responsiveness • Distensibility index of IVC • Collapsability of SVC • Not conducive to continuous monitoring • SVC - TEE
- 134. Monitoring IV Volume Status- Dynamic parameters The end expiratory occlusion test • During MV each insufflation increases intrathoracic pressure - decreases venous return • Interrupting MV during an end-expiratory occlusion can increase preload sufficiently to predict fluid responsiveness • Increase in CO and arterial pulse pressure > 5 % • Reliable in cases of arrythmias and low TV
- 135. Monitoring IV Volume Status- Dynamic parameters
- 136. Monitoring IV Volume Status- Dynamic parameters Passive leg raising • In spontaneously breathing patients • Lifting the legs passively from the horizontal position induces a gravitational transfer of blood from the lower limbs toward the intrathoracic compartment • Blood transferred to heart increases LV preload - challenges Frank Starling curve • Reversible autotransfusion • Easy to use
- 137. Monitoring IV Volume Status- Dynamic parameters Procedure • Elevate lower limbs to 450 (automatic bed elevation or wedge pillow) • At the same time place patient supine from a 450 semirecumbent position • ADV - starting from semirecumbent position induces larger increase in preload because it induces shift from both legs and abdominal compartment • C/I - Intraabdominal hypertension
- 138. Monitoring IV Volume Status- Dynamic parameters
- 139. Monitoring IV Volume Status- Dynamic parameters
- 140. Monitoring IV Volume Status- Dynamic parameters
- 141. Monitoring IV Volume Status- Dynamic parameters
- 142. Monitoring IV Volume Status- Dynamic parameters
Editor's Notes
- #17: Fourier Analysis: Process of analysing a complex waveform in terms of constituent sine waves. Arterial waveform can be broken up into a series of component sine waves with different amplitudes and frequencies Arterial pressure wave consists of a fundamental wave (pulse rate) and a series of harmonic waves (smaller waves whose frequencies are multiples of fundamental freq.) Crude arterial waveform can be reconstructed with 2 sine waves, fundamental frequency and second harmonic. 6-10 harmonics required for distortion free reproduction of arterial waveforms.
- #122: 20% of the circulating volume must be lost before any change in these parameters is seen.
- #129: responsiveness. The minimum volume of fluid to cause a significant haemodynamic effect has been demonstrated to be 4 ml/kg [11&]. Finally, not only the volume of fluid but also the timing of administration is important to consider. It has been recently shown that the longer the duration of the fluid challenge, the lower the proportion of fluid responders
- #130: Positive pressure mechanical ventilation induces a cyclic reduction in left ventricular preload mainly through a decrease in venous return, with this effect more pronounced in hypovolemia.
- #137: hen ventilation is stopped at expiration, the cyclic impediment in venous return caused by each insufflation is interrupted. This leads to an increase in right cardiac preload. The duration of interruption (15 s) is sufficient to allow the resulting increase in right ventricular stroke volume (in case of preload responsive right ventricle) to cross the pulmonary circulation and in turn increase the left cardiac preload. This is an effective preload challenge for both ventricles. The essential limit is that it cannot be used in patients whose respiratory activity does not allow a 15-s hold without interrupting it
- #139: can be used in spontaneously breathing pts, cardiac arrythmias, low tv and low pulmonary compliance The passive leg raising maneuver transfers about 300 ml of venous blood into the right atrium, mimicking a fluid bolus.25
- #140: One of the limitations of the PLR test is that it cannot be performed in some circumstances like during surgical interventions or in patients during prone positioning In addition, this measurement of cardiac output must detect changes in cardiac output in real time to capture the maximum effects of the PLR test, which occur within seconds and vanish after 1 min in some patients pulse contour analysis, VTI by echo or esophageal doppler, changes in end tidal co2 need real time changes
- #142: To circumvent this limit, a ‘tidal volume challenge’ has been developed [33&], which consists inincreasing tidal volume from6 to 8ml/kg for a few minutes. If PPV increases at least 3.5% (in absolute value) during the test, preload responsiveness is likely [33&]. The test has the advantage of not requiring a direct measurement of cardiac output Sometimes, even during normal tidal volume ventilation, it can be difficult to interpret PPV, when its value lies in a zone of uncertainty (between 9 and 13%) described by Cannesson et al. as a [35] ‘gray zone’. A recent study showed that in such a situation, the increase in PPV predicted fluid responsiveness when tidal volume was increased from 8 to 12ml/kg