Arterial pressure monitoring

Arterial pressure monitoring

Indications

· to continuously monitor arterial pressure on patients who are haemodynamically unstable or have the potential to become haemodynamically unstable

· to continually monitor response to vasoactive drug therapy

· to facilitate frequent arterial blood gas sampling - maintaining respiratory management

· to determine derived haemodynamic profile

Common sites for intra-arterial lines are radial, dorsalis, paedis, brachial, femoral (not ideal due to high incidence of infection).

Insertion Consider administration of local anaesthetic if patient is not sedated.

Equipment Procedure trolley, arterial cannula, persist plus, opsite, tape strips to secure cannula, sterile swabs, sterile gloves and gown, blue sheet, 500 mls N/Saline with 500 units heparin, transducer set and pressure bag.

Procedure

· educate and re-assure patient re procedure

· prepare monitor, flush solution and transducer equipment®Pressure bag 300mmhg

· assist medical officer to prepare site with persist plus swabs, administer local anaesthetic (1% Lignocaine) if required, cannulate artery, allow catheter to fill with blood, secure tightly.

· ensure flushing device operational and arterial wave-form visible, zero the transducer to atmospheric pressure(mid- axilla , 4^th intercostal space)secure cannula with steri-strips, cover with opsite and check correlation between arterial and cuff pressure measurement
Note: Ensure adequate marking of arterial cannula (red arterial sticker and red stop cock bung) to reduce risk of accidental administration of medication via arterial route

Complications of insertion

· air embolus introduction into the circulation if improper flushing and connection of cannula occurs

· excessive blood loss if connections are not secured or valve is accidentally left open, or cannula is dislodged

· inaccurate pressure readings may occur if transducer height incorrect

· damping of the waveform may occur if

a. cannula lodges against arterial wall.
b. clot formation.
c. kinking of the catheter.
d. air trapped in transducer.

· infection may occur if poor aseptic technique is used during insertion or
maintenance of arterial cannula

· median nerve damage may occur if the wrist remains dorsiflexed

· haematoma may result with possible nerve compression at the insertion site

Management

· continually monitor arterial pressure wave form and note digital blood pressure reading. Check cuff pressure 4/24 to assure accuracy of haemodynamic monitoring

· 1/24 and as required neurovascular assessment of insertion site, pulse (Ulnar and Brachial if radial used), colour, warmth and tingling/numbness

· withdrawal of blood for blood gas analysis and other varied blood assessments

Attach 5ml syringe to three-way tap; turn top off to monitoring system (open to patient) and withdraw approximately 5ml of blood; turn tap half way towards original position and discard 5ml syringe; attach heparinized syringe to three-way tap, turn tap off to monitoring system (open to patient) and withdraw 1-2ml blood if ABG required; substitute heparinized syringe for general syringe if other blood assessment required; turn tap to original position and remove blood sample, cap ABG sample and remove any air bubbles in heparinized syringe. Utilizing the flushing device, turn tap off to patient (open to flushing device) and flush
access port into sterile gauze swab, turn tap to original position and apply new orange bung. Manually flush arterial cannula and observe arterial pressure wave form.

· the puncture site should be checked each shift for evidence of infection and the site redressed every 3 days

· check the system each shift to ensure that there is no air or blood in the lines and pressure cuff remains inflated to 300mmhg

· the arterial trace should always be visible on the monitor screen

· change the pressurised bag as necessary using 500mls normal saline /500units heparin

8. the lines are changed (and dated) every 7 days

NB. The arterial pressure waveform changes its contour when recorded at different sites along the arterial circuit. These waveform changes are due to decreased compliance of the peripheral arteries and to reflection of previous waves. Systolic pressures tend to rise as the pulse wave propagates distally, and diastolic tends to fall. The mean arterial pressure remains the same from the aorta to the distal branches unless there is narrowing proximal to the measurement site.

· if an arterial line bleeds, compress the artery for 5-10 minutes and call for help

· extremity to be visible at all times

· apply pressure for 5-10 min. post removal, longer if the patient is anticoagulated

· cover insertion site with sterile clear dressing

Zeroing the transducer

At the beginning of each shift a manual check of the patient’s blood pressure is performed and the arterial line is re-zeroed. To zero the transducer, turn the three-way stopcock off to the patient and remove the bung. Press the AP zero key (P1) on the monitor, which will count down 3-2-1- to zero on the screen. Replace the three-way stopcock and bung to patient. Ensure you have a pressure wave back on the screen. NOTE: The patient does not have to be lying flat to have this procedure performed.

Removal

Pressure on the puncture site should be maintained for 5 full minutes or longer if required on removal of the cannula to prevent haematoma and false aneurysm formation. Once a tight occlusive dressing is applied leave the arm exposed and check frequently for bleeding or haematoma. Remove tight dressing in four hours

NB. Blood samples for blood cultures can not be taken through this line