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Arterial_and_CVP_monitoring.ppt
- 1. CENTRAL VENOUS CATHETERS, INVASIVE & NON- INVASIVE BLOOD PRESSURE MONIITORING
- 2. Central Venous Catheter/Central Line is: A catheter inserted into a large vein of the body the tip of which lies in or very near to the right atrium
- 3. Indications: Venous access Infusion of peripherally irritant substances e.g. caustic drugs, ionotropic drugs Administration of TPN To measure central venous pressure (preload) Removal of air embolism
- 4. ContraIndications: Known deficiencies in collateral circulation, Raynauds phenomenon, Thromboangitis obliterans, Brachial artery insufficiency Infection of the site Trauma to the proposed site Excessive anticoagulation
- 5. Insertion sites Various Most common: Jugular vein Subclavian vein Also: Femoral vein Cephalic vein External jugular vein Brachial vein Umbilical vein Basilic vein
- 6. Insertion Sites Internal jugular vein Right side usually used, lower risk of thrombus formation (due to rapid blood flow rates), arterial involvement & pneumothorax. Risk of air embolism, damage to carotid artery, trachea.
- 7. Subclavian vein Lower infection rates, patient comfort, lower risk of thrombus formation (due to rapid blood flow rates), displacement of catheter less likely. Risk of pneumothorax, puncture of subclavian artery, air embolism,
- 10. Insertion Aseptic insertion Seldinger technique Trendelenburg position Ultrasound guidance NICE 2002 Chest x-ray Infection risk Multiple lumen catheters versus single lumen catheters - CVP via distal port
- 11. Ports & lumens • 3 or 5 lumen. • To monitor CVP, always connect monitoring line to distal port. • Other ports can be used for fluid / drug administration. • N.B. it takes @ 1ml of fluid to prime the line.
- 12. Potential complications Infection Bleeding Vascular erosion Pneumothorax Arrhythmias Embolism (air or clot) Perforation of RA Cardiac tamponade
- 13. CVAD Bundle Insertion Infection control Review & escalation process Care plan
- 14. Central Venous Pressure is: Pressure exerted by the blood within the right atrium Used to measure right atrial filling pressure Guide to fluid loading and fluid replacement…….. but Also influenced by right ventricular function, transthoracic pressure and venous tone. PRELOAD
- 15. CVP Trace A wave – atrial contraction C wave – tricuspid valve closing (/bulging) X descent – atrial relaxation V wave – atrial filling; increased atrial pressure prior to TV opening Y descent atrial emptying, TV open, blood flows into ventricle
- 17. Transducer recorded CVP Central line attached to a fluid filled transducer system Transducer converts physiological pressure into an electronic waveform Readings in mmHg, continuous and real time
- 18. “Normal Values” 7-14 mmHg (but remember influencing factors) Readings should be taken from phlebostatic axis.
- 21. “Zeroing” Readings have to be taken from the correct point otherwise they will be inaccurate Correct point is the source of the pressure level of the right atrium External anatomical landmark for right atrium is the phlebostatic axis
- 22. Effects of incorrect positioning • If the transducer is too low, this will give us a falsely high CVP reading. • Likewise, if the transducer is too high, this will give us a falsely low reading
- 23. Central venous pressure monitoring: limitations Cardiovascular abnormalities: Systemic venoconstriction (elevates CVP, so hypovolaemia may go unnoticed). RV compliance: if RV is constricted, hypertrophied or ischaemic, then CVP may be falsely high. Tricuspid valve disease: CVP will be elevated. Intracardiac shunts (VSD) make clinical interpretation of CVP difficult.
- 24. Central venous pressure monitoring: limitations • Increased intrathoracic pressure: PEEP, positive pressure ventilation elevate CVP • LV function: CVP and LV filling pressures correlate in health people, but in LV failure & pulmonary disease, CVP will tell you nothing about LV function
- 25. Removal of Line Infection risk – remove as soon as possible Aeseptic procedure Air embolus – head down/flat, valsalva manoevre, air occlusive dressing (24 hours), tip culture and sensitivity.
- 26. INVASIVE & NON- INVASIVE BLOOD PRESSURE MONIITORING
- 27. Indications Intra-arterial blood pressure (IBP) measurement is often considered to be the gold standard of blood pressure measurement. Critically ill patients e.g: sepsis, post-arrest, major trauma Patients undergoing major surgery, anticipated large fluid shifts Surgeries requiring induced or anticipated hypotension Patients who require serial ABG sampling Acute renal failure Mechanical ventilation Failure of indirect arterial blood pressure measurement, e.g. burns or obesity
- 28. Sampling Assessment of collateral blood flow (Allen Test) Procedure for radial sampling Sites for sampling/indwelling line: Radial artery Femoral artery Brachial artery Dorsalis pedis artery
- 29. Allens Test Measuring the flow of arterial blood to the hands. Patient clenches fist for 1 minute Pressure is applied over radial arteries Patient opens fingers of both hands rapidly and colour is examined. Initial pallor should be quickly replaced by rubor (flushed) This may then be repeated using the ulnar artery
- 30. A-line inserted via radial artery Sampling port
- 31. Arterial trace
- 32. Fluid filled monitoring systems It is important to keep the flush bag primed to 300mmHg This delivers 3mls/hr of flush solution & keeps the vessel patent Remember to turn the 3 way tap on the pressure bag off to the pressure bag so that it doesn’t deflate
- 33. Transducer, flush device, flush fluid and pressure bag Arterial BP monitoring line is red
- 34. Zeroing As with CVP, transducer must be level with Rt atrium (@4th intercostal space [phlebostatic axis]) If transducer is positioned to low, ABP will read falsely high If transducer is positioned incorrectly high, then ABP will read falsely low
- 35. Complications Inadvertent arterial drug administration Thrombosis related to: duration of use, size of cannulae, wrist size (arterial diameter), catheter material (Teflon best), flush system, prolonged systemic hypotension, number of insertion attempts.
- 36. Complications cont.. Haematoma, haemorrhage Sepsis: local site, bacteraemia Distal emboli, thumb (see pic) or hand ischemia proximal forearm ischemia. Aneurysm, AV fistulae.
- 37. General troubleshooting • Problem: No waveform Artifact Waveform drifting Unable to flush line Reading too high Reading too low Overdamped waveform
- 38. Underdamping & overdamping A: normal arterial trace B: overshoot (or resonant trace) overestimated SBP, underestimated DBP C: undershoot, underestimated SBP, overestimated DBP
- 39. Square wave test Normal wave form Undershoot Overshoot
- 40. Removal of Art line • Wash hands, put on gloves, gather equipment. • Remove dressing and sutures (if present). • Apply firm pressure to insertion site, pull out line gently. • Apply manual pressure (this may take up to 10 mins or longer), elevate limb if desired to aid haemostasis. • Apply small occlusive dressing, continue to observe for leakage periodically.
Editor's Notes
- IJV – rt side usually used, lower risk of thrombus formation due to rapid blood flow rates, lower risk of hitting an artery, lower risk of causing a pneumothorax Subclavian vein – associated with lower rates of infection, probably more comfortable for pt, but higher risk of hitting an artery on insertion & causing a pneumothorax.
- Why should we measure CVP? Reasons? Patients with hypotension who are not responding to basic clinical management. Continuing hypovolaemia secondary to major fluid shifts or loss. Patients requiring infusions of inotropes. Limitations: in some kinds of heart valve disease and high blood pressure within the lungs, CVP becomes less reliable reflection of Rt sided filling pressure
- Tricuspid regurgitation – loss of waveform due to blood re-entering atrium Tricuspid stenosis – ‘sharper’ waveform due to poor functioning valve Constrictive pericarditis / Chronic inflammation– (thickened fibrotic pericardiam) limiting adequate contraction, therefore poor ejection. Atrial septal defect – Backflow of blood from LA on filling AF - Irregular First degree – c interval (closing of tricuspid) is prolonged. Complete – atrium contracts with ventricle at the same time. Disassociation.
- Pulsatile pressure from the catheter tip is transmitted through the fluid filled monitoring tubing to a pressure sensitive diaphragm / membrane within the transducer. The diaphragm is moved by pressure waves, which are converted into electrical signals. These signals are converted into real time pressure waves on the monitor.
- The phlebostatic axis is located at the fourth intercostal space at the mid-anterior-posterior diameter of the chest wall. This is the location of the right atrium,
- In either case the CVP must be ‘zeroed’ at the level of the right atrium. This is usually taken to be the level of the 4th intercostal space in the mid-axillary line while the patient is lying supine.
- Zeroing eliminates the effects of atmospheric pressure and gives the transducer a neutral point from which to begin measurement.
- THIS IS AN ASEPTIC PROCEDURE – STERILE GLOVES, STERILE FIELD, DRESSING PACK, CLEAN SITE WHEN DRESSING REMOVED THE PATIENT SHOULD BE SUPINE WITH HEAD TILTED DOWN ENSURE NO DRUGS ARE ATTACHED AND RUNNING VIA THE CENTRAL LINE REMOVE DRESSING CUT THE STITCHES SLOWLY REMOVE THE CATHETER IF THERE IS RESISTENCE THEN CALL FOR ASSISTANCE APPLY DIGITAL PRESSURE WITH GAUZE UNTIL BLEEDING STOPS DRESS WITH GAUZE AND CLEAR OCCLUSIVE DRESSING EG TEGADERM
- No absolute contraindications
- Perform Allens test first - radial artery is best: it is most accessible, less susceptible to venous sampling, and easiest to clean (see below). Swab the skin. The original test proposed by Allen is performed as follows:[1] 1 The patient is asked to clench both fists tightly for 1 minute at the same time. 2 Pressure is applied over both radial arteries simultaneously so as to occlude them. 3 The patient then opens the fingers of both hands rapidly, and the examiner compares the colour of both. The initial pallor should be replaced quickly by rubor. 4 The test may be repeated, this time occluding the ulnar arteries. SHOW ABG SYRINGE Small gauge needle should be used - this is much less painful, may eliminate the need for local anesthetic, but local is often used Hold the syringe like a pencil and enter the skin over the site of the palpated pulse, aiming proximally at an angle of 30° Use one hand to feel the radial pulse and insert the syringe at a 30° angle to the skin surface. Advance slowly along the line of the artery until you see a flashback of blood. If you fail to see a flashback, withdraw the needle slowly. Try palpating the artery again. Hold the syringe steady and allow the syringe to fill. You might need to draw back gently on the plunger if using a small needle. Once you have 0.5 ml of blood, withdraw the syringe and press firmly over the puncture site with a gauze pad for 2–3 min. Attach the gauze pad tightly to the skin with tape. Take the needle off the syringe and dispose of it in a hazardous material container. Carefully expel any air from the syringe (some packs have a filter that you can attach to the syringe to help with this). Cap the syringe with the cap provided and tip upside down a few times to mix well. Take the sample to the blood gas machine yourself or, if it needs to be sent to the biochemistry lab, place the sample in a plastic bag with a few ice cubes. Don't forget to put a label on the syringe.
- Dicrotic knotch - secondary upstroke in the descending part of a pulse trace corresponding to the transient increase in aortic pressure upon closure of the aortic valve
- Overshoot causes: long tubing, stiff tubing, increased vascular resistance Undershoot causes: bubbles in tubing, catheter kinks, clots. low flush bag pressure, overly compliant tubing
- Square wave test – (dynamic response testing) Fast flush – there should be no more then 2 oscillations (wave forms) following the fast flush. And the amplitude of each oscilation should be no greater then 1/3rd of the previous oscillation See above example for oscilations after the fast flush.