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1. Haemodynamic monitoring

2. Q1 Are the factors that influence CVP too numerous to make it meaningful?

3. \ INVASIVE BLOOD PRESSURE MONITORING

4. 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

5. 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

6. Radial Artery cannulation Various techniques : Direct cannulation Transfixation Seldinger’s technique Doppler assisted 2-D USG assisted Surgical cutdown

7. Radial Artery Cannulation Technically easy Good collateral circulation of hand Complications uncommon except: Bleeding,hematoma,local vasosapsm , Repeated punctures, infection

8. Perform Modified Allen test

9. 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

10. 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

11. 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

12. 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

13. 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).

14. Fourier analysis

15. 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.

16. 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

17. 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

18. 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.

19. 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 .

20. 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.

21. 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.

22. 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).

23. . Raising height of bed relative to transducer will cause overestimation of BP whereas lowering patient below transducer will cause underestimation BP.

24. 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

25. 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)

26. 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

27. 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.  

28. CARDIAC OUTPUT MONITORING

29. 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 Pacemaker channel  end 14 cm from catheter tip for temporary pace maker insertion. Rapid response thermistor  measuring EF of Rt ventricle Oximetric catheter optical hookup  continuous monitoring of mixed venous O2 saturation Thermal filament located near the tip continuous measurement of CO

30. 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.

31. 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

32. Contraindications Absolute Tricuspid or Pulmonary valve stenosis RA or RV masses Tetralogy of Fallot Relative Severe arrhythmias Coagulopathy Newly inserted pacemaker wires

33. TEMPORAL ASSOCIATION WITH OTHER EVENTS

34. PiCCO

35. DOWNSTREAM CO MONITORS??

36. GDFT

37. Monitoring IV Volume Status

38. 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

39. 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

40. 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

41. DATA SYNTHESIS: The 24 studies included 803 patients; 5 studies compared CVP with measured circulating blood volume, while 19 studies determined the relationship between CVP/ DeltaCVP and change in cardiac performance following a fluid challenge. The pooled correlation coefficient between CVP and measured blood volume was 0.16 (95% confidence interval [CI], 0.03 to 0.28). Overall, 56+/-16% of the patients included in this review responded to a fluid challenge. The pooled correlation coefficient between baseline CVP and change in stroke index/cardiac index was 0.18 (95% CI, 0.08 to 0.28). The pooled area under the ROC curve was 0.56 (95% CI, 0.51 to 0.61). The pooled correlation between DeltaCVP and change in stroke index/cardiac index was 0.11 (95% CI, 0.015 to 0.21). Baseline CVP was 8.7+/-2.32 mm Hg [mean+/-SD] in the responders as compared to 9.7+/-2.2 mm Hg in nonresponders (not significant). CONCLUSIONS: This systematic review demonstrated a very poor relationship between CVP and blood volume as well as the inability of CVP/ DeltaCVP to predict the hemodynamic response to a fluid challenge. CVP should not be used to make clinical decisions regarding fluid management .

42. Monitoring IV Volume Status - Static parameters

43. Monitoring IV Volume Status - Static parameters

44. Monitoring IV Volume Status - Static parameters Mixed Venous Oxygen Saturation S V O 2 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

45. 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

46. Monitoring IV Volume Status - Dynamic parameters

47. Monitoring IV Volume Status - Dynamic parameters

48. 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

49. Monitoring IV Volume Status - Dynamic parameters Not useful Open chest procedures MV with low TV < 8 ml/kg or high PEEP > 15 cm H 2 O Elevated intraabdominal pressures Cardiac arrythmias RV failure Requirement for vasomotor infusions

50. 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

51. 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

52. Monitoring IV Volume Status - Dynamic parameters

53. 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

54. Monitoring IV Volume Status - Dynamic parameters Procedure Elevate lower limbs to 45 (automatic bed elevation or wedge pillow) At the same time place patient supine from a 45 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

55. Monitoring IV Volume Status - Dynamic parameters

56. Monitoring IV Volume Status - Dynamic parameters

57. Monitoring IV Volume Status - Dynamic parameters

58. Monitoring IV Volume Status - Dynamic parameters

59. Monitoring IV Volume Status - Dynamic parameters