invasive blood pressure monitoring in critical care n.
Skip this Video
Loading SlideShow in 5 Seconds..
Invasive blood pressure monitoring in critical care PowerPoint Presentation
Download Presentation
Invasive blood pressure monitoring in critical care

Invasive blood pressure monitoring in critical care

918 Views Download Presentation
Download Presentation

Invasive blood pressure monitoring in critical care

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Invasive blood pressure monitoring in critical care Presented by Ri 施易青

  2. Outline • Introduction • Arterial pressure waveform • Controversial aspect of IBP monitoring • Conditions that affect arterial waveform morphology • Pros and cons of various cannulation sites

  3. History • First invasive blood pressure monitoring: Stephen Hales’ horse (1733) • First attempt in human: Faivre’s amputee (1856) • Clinical use: Lambert and Wood (1947) • Modern cannulation technique: Barr (1961) • CV surgery in the 60s

  4. Indications • Continuous monitoring of BP • Serial external monitoring inadequate • Hypotension or hypertension requiring vasoactive drugs • Respiratory illness or mechanical ventilation requiring frequent blood gases: >3X/D for arterial sticks >5X/D for combined arterial and/or venous sticks • Major Surgery: Especially CV or neuro. procedures

  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. The Pressure-pulse • 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

  7. 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)

  8. Is arterial waveform predictive of cardiac contractility? • It is only “aortic arch pressure” that can be used to measure LV contractility, not “peripheral pressure”

  9. As BP is measured farther into periphery: • 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

  10. Morphology changes as a result of peripheral reflexions: • Reflexion of waves due to the tapering diameter • Reflexion due to changing content of the arterial wall • Reflexion also occur at branching points of vessels

  11. Is the arterial waveform predictive of stroke volume? • The pressure does not predict flow • The distensible aortic arch act as a “fixed-capacity, high pressure reservoir” • Flow in the arterial tree is continuous, with 10-20 percent of LV power being pulsitile

  12. Cullen et al: Correlation coefficient of 0.82 between changes in stroke volume and changes in peripheral systolic pressure in halothane-induced anesthesia status, where peripheral vascular resistance remained essentially unchanged Interpretation of blood pressure measurement in anesthesia Anesthesiology, 40:6 1974

  13. Role of direct arterial pressure monitoring • Provides trends over a wide range • Unreliable as absolute hemodynamic values • As a reminder • “A needle in an artery does not guarantee a pressure or accuracy any more than an endotracheal tube guarantee a patent airway.”

  14. Conditions that affect arterial waveform morphology • Hyperdynamic pulse • Pulsus paradoxus • Reverse pulsus paradoxus • Pulsus alternans • Pulsus bisferens

  15. Hyperdynamic pulse • Aortic regurgitation • AV fistula • Thyrotoxicosis • Anemia • Pregnancy • sepsis

  16. Pulsus paradoxus

  17. Cause of pulsus paradoxus • Change in pleural pressure associated with breathing • Anatomic relationship between two ventricle chambers

  18. D/D of Pulsus paradoxus • Constrictive pericarditis or cardiac tamponade • COPD • Asthma • Tension pneumothorax

  19. Reverse pulsus paradoxus • An exaggeration of the rise in systolic BP during mechanical ventilation • A sensitive indicator of hypovolemia in mechanically ventilated p’t

  20. Pulsus alternans

  21. Cause of pulsus alternans • A sign of decreased myocardial contractility (deletion of the number of myocardial cells contracting on alternate beats) • An alteration in diastolic volume leading to beat-to-beat variation in preload

  22. D/D of pulsus alternans • LV dysfunction • Pericardial effusion

  23. Pulsus bisferens

  24. Pulsus bisferens • Hypertrophic cardiomyopathy • Aortic regurgitation

  25. Advantages and disadvantages on various cannulation sites • Radial artery • Brachial artery • Femoral artery • Axillary artery • Dorsalis pedis artery

  26. Radial artery • Advantages: easy to cannulate, accessible during most type of surgery, good collateral circulation, patient comfort, Allen’s test • Disadvantages: thormbus formation, possible injury to nerve, augmentation of SBP,

  27. Brachial artery • Advantages: easy to cannulate, larger catheter, less SBP augmentation, collateral vessels • Disadvantage: uncomfortable for p’t, median nerve damage

  28. Femoral artery • Advantages: prolonged use, useful in shock p’t, largest catheter • Disadvantages: atherosclerotic plaque may break off, massive hematoma, difficult to immobilize

  29. Axillary artery • Advantages: large size, useful in peripheral artery dz and shock, proximity to aorta, • Disadvantages: neurologic complication, technically difficult

  30. Dorsalis pedis artery • Advantages: dual circulation • Disadvantages: greatest SBP augmentation, thrombus formation, difficult to immobilize, impossible to walk

  31. Take home message • The arterial system functions as a damped, resonant, transmission line, transmitting various frequencies with different degrees of attenuation. • The clinician must dissuade himself from the belief that the peripheral pressure accurately reflects aortic arch pressure.

  32. reference • Monitoring in Anesthesia and Critical Care Medicine, 2nd edition. 1990 • Hemodynamic monitoring: Invasive and Noninvasive Clinical application, 2nd edition.1995 • Cullen et al: Interpretation of blood pressure measurement in anesthesia. Anesthesiology, 40:6 1974

  33. Thanks for your attention!