The purpose of this guideline is to provide guidance in the use of arterial lines at Great Ormond Street Hospital (GOSH).
Invasive arterial pressure monitoring is used when:
- Continuous accurate monitoring of blood pressure is required in theatres, intensive and high-dependency care settings, and during the inter-hospital transfer of acutely unwell children.
- Frequent blood sampling is required, especially arterial blood gases.
- A withdrawal site is needed in patients who require exchange transfusions.
Arterial cannulae are normally only used during short periods of acute or critical illness.
Note: While this guideline refers to the ‘child’ throughout, all activities are applicable to young people.
Arterial cannulae may be sited in the radial, femoral or axillary arteries using percutaneous puncture ( Ewens and Jevons 2007; Singer and Webb 2009). Brachial arteries should be avoided as there are more risks associated with their use ( Rationale A). Care of the arterial line is more important than the site chosen for insertion.
Umbilical arteries may be used in the newborn but their care and management are not included in this guideline.
The components of an arterial pressure monitoring system are ( Garretson 2005):
- An indwelling cannula from which arterial pressures are continuously measured.
- An arterial line set, which has low compliance tubing for accuracy in monitoring ( Rationale 1).
- A valved flow-limiting device connected to a syringe pump or arterial line pressure bag ( Rationale 2).
- The arterial line set has access ports or 3-way taps (3WT) ( Rationale 3, Rationale 4).
- The arterial line is attached to a transducer that enables the mechanical energy of the arterial pressure to be transformed into an electrical signal for display as a waveform by a haemodynamic monitoring system (monitor) ( Rationale 5).
All those involved in the siting and management of an arterial cannula must be trained and competent in the techniques involved ( Rationale 6, Rationale 7). This includes:
- site selection
- how to access them
- how to maintain patency
- how to recognise and manage potential difficulties
Patency is maintained with a solution of 0.9 per cent sodium chloride for infusion with one unit of heparin per ml (known as heparinised sodium chloride)( Rationale 8, Rationale 9). It is administered at a rate of 0.5-3ml per hour ( Rationale 10)( Dougherty and Watson 2011). Heparin may be omitted especially in patients with severe bleeding disorders ( Rationale 10b)( Blackmore et al 1998; Cardinal et al 2000; Gamby and Bennett 1995; Heap et al, 1997; Lua et al 1997).
0.45 per cent sodium chloride maybe used in neonates and patients with high serum sodium.
Drugs and hypertonic solutions must never be given via an arterial line ( Rationale 11)( National Patient Safety Agency (NPSA) 2008a; NPSA 2008b).
It is imperative that arterial lines are clearly labelled as such ( Rationale 12). The cannula site must be exposed and continually observed ( Rationale 13)( Garretson, 2005). The patient must not be left unattended ( Rationale 13)( Ewens and Jevons 2007; Woodrow 2009).
Potential problems associated with arterial lines are ( Burns and Chulay 2010):
- Decreased or absent pulse distal to the puncture site.
- Bleed back into tubing or transducer.
- Local infection.
Standard (universal) precautions and an aseptic non-touch technique (ANTT)( Pratt et al 2007; Great Ormond Street Hospital (GOSH) 2012a) must be adhered to when siting, manipulating, accessing or removing an arterial line ( Rationale 14). Visors or other appropriate eye protection is essential due to the high pressures associated with bleeding from arterial sites.
An arterial cannula should be changed or removed if:
- bacteraemia is suspected ( Rationale 15)
- local infection noted ( Rationale 15)
- the extremity blanches ( Rationale 16)
- it is no longer necessary
- arterial trace has been lost and unable to sample despite troubleshooting
A trained and competent practitioner may withdraw blood for laboratory analysis at any time. An alternative method of blood sampling which may be considered is:
Assembling the components to provide an intra-arterial monitoring system needs to be performed, or supervised, by a trained and competent practitioner prior to cannulation ( Rationale 7; Rationale 18).
There are two delivery methods of intra-arterial infusion ( Hazinski, 1992) which provide different levels of accuracy of fluid administration.
A syringe pump with a variable pressure alarm. It is used when:
- warranted by the patient’s age and condition, eg neonates and intensive care patients
- an accurate record of fluid administration is required
- an alarm monitor for prompt detection of occlusion is required
A high-pressure bag with manual pressure gauge, which provides a less accurate record of volume of fluid administered.
The choice of system is dependent on:
- the degree of fluid accuracy required
- medical device resource availability
- the risk assessment made by the practitioner
- anticipated clinical requirements
The following equipment should be gathered to set-up the system:
- arterial line set
- heparinised 0.9 per cent sodium chloride ( Rationale 19)
- haemodynamic monitoring system (monitor)
- pressure bag or
- syringe pump, dispensing pin and 50ml syringe
Check the arterial pressure monitoring system for any faults or loose connections.
Using ANTT, prime thoroughly with either heparinised 0.9 per cent sodium chloride or a prescribed approved fluid ( Rationale 10, Rationale 20, Rationale 21).
- air is thoroughly removed from the arterial line set
- all connections are secured, primed and airtight
- all ports are thoroughly primed
- the system is clearly labelled
Preparation: child and family
Explanation to children and families should be included as part of the whole preoperative preparation, where appropriate, although an arterial line is usually placed in children in theatres or on the Intensive Care Unit (ICU) ( Rationale 22). Where children have presented in emergency settings detailed explanations may have to be given or repeated for families after the initial resuscitation process. Normally the child will be anaesthetised or heavily sedated during this time. Preparation needs to take into account the child’s age, the level of dependency of their condition and the urgency of the procedure ( Rationale 23, Rationale 24).
Explain the procedure to the child and family, avoiding medical jargon, including the following ( Rationale 25):
- that a cannula is necessary
- the reason for the cannula
- what it entails
- the potential risks of a cannula
- the length of time it is likely to be in situ
Standard universal precautions must be adhered to, ie gloves, an apron, and a visor is recommended for the procedure ( Pratt et al 2007; GOSH 2012a).
- Perform a hand wash.
- Collect plastic tray. Immediately prior to use, the dry tray should be inspected for cleanliness and wiped with a 70 per cent isopropyl alcohol wipe. Clean all surfaces of the tray internally and then externally. Once cleaned, allow time to dry.
Only a suitable trained and competent practitioner should undertake arterial cannulation ( Rationale 26).
Prepare the following equipment on the clean tray ( Rationale 14, Rationale 28):
- Dressing pack.
- 0.9 per cent sodium chloride for injection (5mls).
- Two x 2ml syringes.
- One x 5ml syringe.
- Three x 21G needles.
- Two x cannula: Abbocath® size 22G.
- 3 Way Tap (3WT)
- Two per cent chlorhexidine in 70 per cent isopropyl alcohol solution or Chloraprep® applicator.
- One x short 15cm low compliance extension tubing eg Lectrocath™.
- Lidocaine one per cent.
- Skin closures (eg Steri-Strips™).
- Transparent dressing (eg Opsite3000™).
Select the most appropriate artery to cannulate. In children the radial artery is preferred ( Rationale 29, Rationale 30, Rationale 31) but femoral or axillary arteries may be used. The brachial artery is not recommended if other sites are available and the ulnar or posterior tibial vessels are not used ( Rationale 32, Rationale 33).
Arterial cannuale are only sited in sedated or anaesthetised children at GOSH. However, if for any reason placement of an arterial line is being considered in an awake child then administration of intravenous analgesia and sedation may be required as well as local infiltration of the area with one per cent lignocaine ( Advanced Paediatric Life Support, 2005)( Rationale 34, Rationale 35).
Before using the radial artery check that an ulnar artery is present and patent. Allen’s test must be performed for this ( Rationale 36)( Perrin 2008):
- occlude both arteries at the wrist
- release the pressure on the ulnar artery
- observe the circulation returning to the hand, ie it will flush pink
- if this does not happen, do not proceed with a radial puncture on that side
If a posterior tibial (PT) is being inserted check circulation using Allen's test as above but using PT pulses.
Seek the assistance of a colleague to position the child as follows ( Rationale 37):
- Radial artery: hyperextend and restrain the wrist over small roll ( Rationale 38).
- Femoral artery: elevate buttocks with a small roll.
- Posterior tibial: externally rotate leg and foot.
- Axillary artery: rotate arm to the 'How position' (ie hand to ear). Place a rolled up towel under the chest to rotate the axilla upwards.
The colleague should also assist with the securing of the device and provide distraction if appropriate. Consider ultrasound guidance with cannulation.
To cannulate an artery
- Perform a surgical hand wash ( Rationale 14).
- Put on protective clothing, including non-sterile gloves and eye protection ( Rationale 14).
- Identify the vessel by palpation ( Rationale 39).
- Establish a sterile field.
- Cleanse the skin at intended cannulation site with two per cent chlorhexidine and 70 per cent isopropyl alcohol for at least 30 seconds and leave to dry ( Rationale 40).
- Do not fan or blow the site to speed up the drying process ( Rationale 41).
- Do not re-palpate the artery once the skin has been cleansed ( Rationale 41).
- Unless the patient is a neonate ( Rationale 42) infiltrate the skin with a very small volume of one per cent Lignocaine. This is not indicated in the sedated or anaesthetised child.
- Un-sheathe the cannula and hold it firmly so that the two component parts cannot become separated.
- Examine the cannula for faults ( Rationale 43).
- Attach a 2ml syringe.
- Gently stretch the skin over the artery ( Rationale 44).
- Insert the cannula through the skin parallel to the vessel at an approach angle of 45° and advance it slowly ( Rationale 45).
- If the vessel is not entered, pull back slowly as an artery may be transfixed. If so, advance after flashback of blood. If not, pull back the skin and redirect, ensuring the needle does not become blocked thus preventing adequate flashback.
- When the artery is punctured blood will be seen to pulsate in the syringe.
- Collect the required amount of blood in the syringe for any urgent analysis.
- Decrease the angle of the cannula so that it is resting on the skin and withdraw the stylet slightly.
- A second flashback of blood will be observed up the shaft of the cannula; blood may rush back or be easily aspirated.
- Slowly advance the cannula over the needle with a twisting motion. This should secure the successful cannulation of the vessel ( Rationale 46).
- A vigorous arterial spurt is the best evidence of successful arterial cannulation.
- If the artery is entered but the catheter cannot be fully advanced, an appropriate guide wire, eg Cook Positive Placement wire or a Kimal™ guide wire (size 0.18 for a 22G cannula) may help.
- Never re-advance the needle into the cannula ( Rationale 47).
- During attempted arterial line cannulation sluggish back flow indicates either inadvertent venous cannulation or para-arterial placement, ie a haematoma.
- Press firmly on the artery to occlude the blood flow, keep the cannula in position and withdraw the stylet.
- Continuing to protect the cannula, connect a 5ml syringe and flush with 0.9 per cent sodium chloride for injection ( Rationale 48, Rationale 49).
- Check the site for swelling and skin blanching.
- Occlude the artery, remove the syringe and connect to the arterial line set primed with heparinised 0.9 per cent sodium chloride.
- Taking care at all times to protect the cannula, apply two x 1cm skin closures and a sterile clear dressing ( Ewens and Jevons 2007; Burns and Chulay 2006). Some additional secure strapping of the tubing may be required to ensure adequate fixation while maintaining good site visualisation ( Rationale 14, Rationale 50).
- Apply an appropriate size splint but leave cannula visible for regular inspection. Radial lines should be splinted with the wrist extended ( Rationale 51).
- Attach arterial line set to the transducer and monitor.
- Calibrate the transducer following the manufacturer’s instructions (see maintenance: calibration).
- Observe arterial trace on the monitor for appropriate waveform ( Rationale 52).
- Blood pressure recording maybe compared to non-invasive blood pressure recording as required or according to local policy ( Rationale 53, Rationale 54).
- Dispose of all equipment correctly as per disposal of used sharps policy ( GOSH 2014)( Rationale 55).
- Remove gloves.
- The plastic tray should be washed with hot water and neutral detergent (washing up liquid). Chlorhexidine-based or other hand wash products are not suitable for this purpose.
- After washing, the tray should be dried with a paper towel and stored in a dry area away from the sink to avoid re-contamination.
- Infectious patients: prior to the tray being taken out of the bed space/room, it should be cleaned with a decontaminating wipe, eg Tuffie 5. Following that, it should be washed with hot water and neutral detergent, dried and stored as above.
- Perform a social hand wash.
Document the cannulation in the child’s health care records ( Rationale 56).
The transducer must be calibrated ( Rationale 57, Rationale 58, Rationale 59, Rationale 60)( Garretson 2005):
- Following insertion of an arterial cannula.
- At the beginning of every shift.
- Whenever the child’s position is changed.
- When transducer set is changed.
- Blood pressure recording maybe compared to non-invasive blood pressure recording as required or according to local policy.
- Using the mid clavicle as a guide, locate the fourth intercostal space and follow this space across the chest wall to the mid axillary line ( Ewens and Jevons 2007).
The position of the child can be either:
- lying flat or
- their head not elevated by more than 45 degrees ( Rationale 62)
To calibrate the transducer ( Philips Electronics NV 2006):
- Level the transducer at the phlebostatic axis using a spirit level if necessary ( Rationale 63).
- Turn the 3WT off to the child ( Rationale 64).
- Turn the 3WT on to the atmosphere (air).
- In the setup menu for the pressure, select zero ‹press›.
- When you see the message ‹press› zero done at ‹date and time› on the status line (for example ABP zero done at 23 May 10 20:30) turn the 3WT off to the atmosphere and turn the 3WT on to the child.
Select waveform size:
- in the setup <ABP> menu select scale ( Rationale 65)
- select a value from the pop up list
- use a scale which is appropriate for the child’s arterial blood pressure range ( Rationale 66)
- select ›optimum‹ and the medical device will regulate the size of the waveform in relation to the patients current monitoring ( Rationale 67).
To choose a label for the arterial monitoring:
- In the setup ‹press› menu, select Label ( Rationale 68).
- Select the appropriate label from the list: ABP - arterial blood pressure.
Adjust alarm limits:
- In the setup ‹press› menu, select Alarms from and choose the source ( Rationale 69).
- Select and set the high limit and low limit for the pressure(s) you have selected.
Maintenance: maintaining patency
Intermittent irrigation is not advocated and not recommended ( Rationale 48, Rationale 73).
Heparinised 0.9 per cent sodium chloride should be continually infused to maintain patency ( Rationale 19, Rationale 74).
- The recommended concentration is one unit of heparin per ml of 0.9 per cent sodium chloride or
- An approved fluid as prescribed ( Ewens and Jevons 2007).
Administer a continuous infusion at 0.5-2mls/hour via either a syringe pump or pressure bag. The infusion pressure must be higher than intra-arterial pressure 150-200mmHg ( Rationale 72, Rationale 75).
Manual flushing of the intra-arterial administration set should be kept to a minimum ( Rationale 76, Rationale 77). Following blood sampling, always flush the line (see blood sampling).
The administration set must be changed every 72 hours or more frequently if clinically indicated. ( Rationale 14)( Garretson 2005; Pratt et al 2007).
The patient must not be left unattended ( Rationale 13, Rationale 79)( Ewens and Jevons 2007; Woodrow 2009).
Any abnormalities should be reported to the medical staff immediately ( Rationale 64, Rationale 80).
The circulation of the cannulated limb should be continuously monitored for signs of the following ( GOSH 2012b):
- decreased pulse ( Rationale 81)
- blanched colour ( Rationale 82)
- cool skin/extremities ( Rationale 83)
- sluggish capillary refill time
- pressure ulcers
All observations must be recorded in the child’s health records ( Rationale 56).
The cannula must be removed if there is sustained blanching to the limb, distal to the cannula site ( Rationale 84)( Ewens and Jevons 2007).
Observe for signs of cannula displacement into the tissues which will be ( Rationale 64, Rationale 85):
- lack of a normal arterial waveform
- fluid leakage
- pain or discomfort ( Ewens and Jevons 2007; Burns and Chulay 2006)
- temperature change
- Apply firm pressure to the cannula site for five to 15 minutes ( Rationale 88)( Burns and Chulay 2006).
- Ensure the cannula is secure and immobilised with a splint ( Rationale 89).
- If necessary clean site and re-secure dressing when bleeding has stopped ( Rationale 90).
Accidental removal of the arterial cannula will require immediate application of pressure to the site for five to 15 minutes or until bleeding has stopped ( Burns and Chulay 2006).
The site should be covered with a sterile dressing until site has healed.
The administration set and other intra-arterial tubing must be checked ( Perrin 2008; Garretson 2005) to ensure:
- all tubing remains secure ( Rationale 91)
- there are no kinks in the tubing ( Rationale 92)
- that a continuous infusion of heparinised sodium chloride is maintained ( Rationale 93)
- stability of pressure on infusion device ( Rationale 94, Rationale 95)
- any pyrexia should be acted upon according to local policy ( Rationale 98)
- any rigor following the use of the cannula should be reported ( Rationale 99)
The cannula should be re-sited when clinically indicated and when:
- any signs of ischaemia to limb
- the child is pyrexial
- there are signs of local inflammation
Maintenance: pressure monitoring
A haemodynamic monitor consists of an amplifier that enhances the signal, which is then converted into a digital display and an oscilloscope trace.
Arterial waveform analysis provides valuable information as well as the absolute systolic and diastolic pressures ( Garretson 2005).
The normal wave should have a sharp peak systole upstroke, clear dicrotic notch and a definite end diastole ( Garretson 2005)(see appendix 1 (PDF)).
The practitioner must ensure continuous, accurate monitoring and recording of arterial blood pressure by:
- Setting the monitor to display the arterial pressure trace and numerical values ( Rationale 100).
- Ongoing observation of the pressure trace ( Rationale 64).
- Setting appropriate alarm limits ( Rationale 101).
- Documenting blood pressure readings hourly or more frequently if the patient’s clinical condition dictates ( Rationale 56).
- Record hourly heparinised 0.9 per cent sodium chloride or approved fluid on the child’s fluid balance chart.
If altered waveform is observed take appropriate action ( Rationale 53) (see troubleshooting).
Blood pressure recording may be compared to non-invasive blood pressure recording as required or according to local policy.
Invasive (direct) monitoring provides more accurate blood pressure readings than non-invasive (indirect) techniques, especially in the critically ill. Arterial recordings may be 5-10 mmHg higher than non-invasive measurement ( Rationale 102)( Singer and Webb 2009; Adam and Osborne 2005).
Perform cuff blood pressure with an appropriate sized cuff in relation to the child’s size and avoid any limb with an infusion ( Rationale 64, Rationale 103, Rationale 104).
Maintenance: site care
The cannula must be secured with a sterile clear dressing ( Garretson 2005) and anchored with sutures or skin closure strips ( Rationale 14, Rationale 50, Rationale 79, Rationale 86).
Change the dressing if:
- it is ineffective in securing the cannula ( Rationale 105)
- it is not keeping the site of entry clean ( Rationale 14)
- the cannula is kinked under the dressing
- bleeding has occurred
Inform the child and family of the following ( Rationale 22, Rationale 23, Rationale 24, Rationale 25):
- that the cannula needs to be re-dressed
- the reason for the access
- what it entails
- the likely duration of the procedure
- a clear dressing or an approved dressing product ( Rationale 86, Rationale 87)( Garretson 2005)
- two per cent chlorhexidine in 70 per cent alcohol or Chloraprep® applicator or 10 per cent povidone-iodine applicator ( Rationale 14, Rationale 40)
- sterile gauze and sterile sodium chloride
To change an arterial line dressing:
- ANTT and standard precautions must be adopted ( Rationale 27).
- Perform a hygiene hand wash and put on non-sterile gloves.
- Carefully remove the old dressing, holding the cannula in place at all times ( Rationale 79).
- Thoroughly inspect the site of entry of the cannula for any signs of infection ( Rationale 86).
- If necessary, clean the area using two per cent chlorhexidine in 70 per cent isopropyl alcohol or 10 per cent povidone-iodine in accordance with agreed local procedures.
- Apply the new clear dressing remembering to protect the cannula at all times ( Rationale 79).
- Re-apply the splint ensuring that it is secure and avoids occluding the visibility of the cannula site or circulation of the limb.
Only a suitably trained and competent practitioner should undertake any troubleshooting ( Rationale 64).
Any changes in the patient’s condition should be reported immediately to the medical staff.
- Assess patients’ cardiovascular status, including pulse check, ECG waveform and non invasive blood pressure ( Rationale 106).
- Check arterial line site, all connections and infusion device flow rate ( Rationale 107).
- Check appropriate arterial scale in use on monitor.
- Check arterial line set (dome if used) for clots, air or inadequate filling and change entire system if necessary.
- Check blood can be easily aspirated at access port.
- Attempt to aspirate any clot, using 2ml of heparinised sodium chloride syringe. Lightly 'bounce' plunger to loosen blood clot ( Rationale 108)( Burns and Chulay 2006).
- Do not forcefully flush catheter if resistance is high ( Rationale 109).
- Redress cannula site, check for kinks or poor positioning of cannula ( Rationale 110).
- Reposition the child or their cannulated limb ( Rationale 110).
Abnormally high or low readings must be investigated ( Rationale 111).
- Assess patient’s cardiovascular status, including pulse check, ECG waveform and non invasive blood pressure to ensure it is a monitoring problem, not a change in the child’s condition.
- Observe trace for catheter fling ( Ewens and Jevons 2007).
- Position transducer level with right atrium.
- Ensure low compliance tubing of minimal length used.
- Recalibrate transducer ( Rationale 112, Rationale 113, Rationale 114).
Bleeding puncture site
If bleeding occurs at the puncture site:
- Apply firm pressure to insertion site for five to 15 minutes ( Rationale 88)( Burns and Chulay 2006).
- Ensure catheter is securely strapped and adequately sutured ( Rationale 115).
- Ensure limb is immobilised.
- Check circulation in extremity ( Rationale 78).
- If circulation is compromised distal to the puncture site:
The cannula must be removed if there is sustained blanching to the limb, distal to the cannula site ( Ewens and Jevons 2007).
If there is no waveform visible on the monitor:
- Assess patient’s cardiovascular status, including pulse check and non invasive blood pressure to ensure it is a monitoring problem, not a change in the child’s condition.
- Check system is correctly set up and attached ( Rationale 64) ( Garretson 2005).
- Check appropriate arterial scale in use on monitor ( Rationale 117).
- Check monitor display settings correctly set.
- Try an alternative transducer and module ( Rationale 118).
- Consult biomedical engineer ( Rationale 119).
If electrical interference is experienced ( Rationale 120):
- inspect transducer and cable for cracks ( Garretson 2005)
- use another transducer
- consult biomedical engineer
Only staff that have received appropriate training and are competent should access an arterial cannula to take blood samples ( Rationale 64).
The procedure must be stopped and assistance sought if any of the following occur:
- resistance is felt ( Rationale 121)
- the child reports pain ( Rationale 122)
- swelling is observed around the entry site ( Rationale 108)
- leakage of fluid onto dressing ( Rationale 51)
- redness around the arterial line site or along the artery ( Rationale 51, Rationale 97)( Woodrow 2009)
Depending on the blood tests required gather the suitable equipment. This could include:
- blood bottles or vacuum collection systems
- one x 2-5ml syringe (for dead space)
- one x 2-10 syringe (if required for bloods samples)
- wipes impregnated with two per cent chlorhexidine in 70 per cent alcohol (eg Clinell® wipes)( Rationale 14)
- sterile hubcap
- syringe cap
- protective sheet/paper towel
- non sterile gloves
- blood gas analyser eg I-Stat™ and Cartridge
- blood glucose analyser eg Glucometer™ and Cartridge
An extra person may be needed to help with the procedure ( Rationale 64, Rationale 85, Rationale 123).
Standard precautions must be adopted when blood sampling from an arterial line, ie non-sterile gloves, visor and apron; ANTT must be used ( Rationale 14; Rationale 27)( GOSH 2012a).
If it is difficult to obtain blood, seek assistance from a doctor or an experienced practitioner ( Rationale 121, Rationale 124).
Blood sampling: using a syringe pump or pressure bag and not replacing dead space
- Gather equipment required (see above).
- Perform a hand wash and put on non sterile gloves ( Rationale 14).
- Open packaging.
- Place equipment the clean tray using ANTT.
- Place protective sheet/paper in the appropriate place ( Rationale 125).
- Press STOP if syringe pump is being used for heparin infusion or CLAMP pressure bag administration line ( Rationale 126).
- Remove the cap from the hub of the sampling port.
- Clean hub for 30 seconds using friction with a two per cent chlorhexidine in 70 per cent isopropyl alcohol wipe (eg Clinell® wipe) and allow to dry naturally ( Rationale 14).
- Connect 2-5ml syringe.
- Open 3WT to patient and syringe and withdraw 3mls of blood ( Rationale 128).
- Turn 3WT off to child/infusion ( Rationale 72, Rationale 129).
- Remove the syringe.
- Place the syringe on a clean tray.
- Re-access the device using a 2-10ml syringe or Monovette™ system ( Rationale 130).
- Open 3WT to child and syringe.
- Withdraw the required quantity of blood.
- Turn 3WT off to hub.
- Remove syringe containing the blood sample.
- Place the cap on the sample.
- Turn 3WT off to child and open the infusion and hub ( Rationale 14, Rationale 108).
For syringe pumps:
Press PURGE and simultaneously release flow limitation valve to clear the hub ( Rationale 14, Rationale 131).
For pressure bags:
Check the infusion pressure is set correctly on the pressure bag ( Rationale 132).
Open clamp on the pressure bag administration line.
Release the flow limiting valve to clear the hub.
- Observe for hub clearance.
- Turn 3WT off to hub and open to the infusion and child.
- Remove the syringe and place a sterile cap onto the hub.
For syringe pumps:
Press START on the syringe pump ( Rationale 70).
Press BOLUS and simultaneously release flow limiting valve to clear the line ( Rationale 133).
For pressure bags:
Using the flow limiting valve, flush the line for two to three seconds ( Rationale 134).
- Observe for blanching ( Rationale 82).
- Switch all alarms back on ( Rationale 64).
- Observe trace and check the parameters are set appropriately.
- Place the blood collected in the appropriate bottles if required.
- Observe the monitor for normal trace ( Rationale 134).
- Ensure the arterial line is secure ( Rationale 79).
- Perform bedside blood analysis tests, ie blood gases/glucometry ( Rationale 135).
- Label the samples and send them with the completed request forms to the correct laboratory.
Record the taking of the blood sample in the child’s health care records ( Rationale 56).
Blood sampling: using a syringe pump or pressure bag and replacing dead space
The dead space fluid taken during arterial blood sampling may be replaced, particularly when frequent samples are taken or if the child weighs less than 10kg ( Rationale 135).
- Assess dead space fluid ( Rationale 137).
- Connect the syringe containing dead space fluid to the hub.
- Turn the 3WT open to the child and syringe ( Rationale 82, Rationale 138).
- Replace the dead space fluid slowly.
- Leave syringe in hub.
- Turn 3WT off to patient and open to infusion and syringe ( Rationale 14).
- Press PURGE and simultaneously release flow limiting valve to clear the hub ( Rationale 131).
For pressure bag:
- Assess dead space fluid ( Rationale 137).
- Connect the syringe containing dead space fluid to the hub.
- Turn the 3WT open to the child and syringe ( Rationale 82, Rationale 138).
- Replace the dead space fluid slowly.
- Leave syringe in hub.
- Check the infusion pressure is set correctly on the pressure bag ( Rationale 139).
- Open clamp on the administration line.
- Turn the 3WT off to the child and open to the infusion and syringe.
- Release the flow limiting valve to clear the hub ( Rationale 14, Rationale 131).
Follow steps 22-24 as above.
For syringe pumps:
- Press BOLUS and simultaneously release flow limiting valve to clear line ( Rationale 133).
For pressure bags:
- Using the flow limiting valve, flush the line for two to three seconds ( Rationale 140).
Removal of arterial cannula
The arterial line should be removed when ( Burns and Chulay 2006):
- limb circulation is compromised
- the cannula is misplaced
- it is no longer required for monitoring and frequent blood sampling
- there are signs of an infection
Check the normal daily coagulation blood levels ( Rationale 141).
Patients with severe clotting disorders may require an infusion of depleted clotting factors, eg fresh frozen plasma, immediately prior to arterial cannula removal.
Inform the child/young person and family of the following ( Rationale 22, Rationale 23, Rationale 24, Rationale 25):
- why the arterial line needs to be removed
- what this entails
- non-sterile gloves
- sterile gauze
- surgical tape
- small sterile plaster (if required)
- stitch cutter (if required)
To remove the line:
- Put on clean apron and visor ( Rationale 27).
- Perform a social hand wash ( Rationale 27).
- Gather equipment required (see above).
- Perform hygiene hand wash and put on non-sterile gloves ( Rationale 14).
- Open packaging.
- Place equipment on clean tray using ANTT.
- Loosen all dressings ( Rationale 142).
- Cut retaining suture if present and withdraw the line from the artery without applying pressure ( Rationale 143).
- Using the sterile gauze immediately apply pressure for up to five minutes or until bleeding has stopped ( Rationale 88, Rationale 144).
- Apply a sterile plaster or a pressure dressing over the arterial line site ( Rationale 14).
- Observe the site regularly for bleeding every five minutes for the first 15 minutes, then every hour.
Rationale A: The brachial is an end artery ( Lua et al 1997). Cannulation of the ipsilateral radial or dorsalis pedis may result in the development of digital ischaemia ( Lua et al 1997).
Rationale 1: Low compliance tubing prevents the loss of the pressure signal through tubing expansion when monitoring ( Garretson 2005).
Rationale 2: To ensure continuous pressurised fluid irrigation of the catheter during monitoring.
Rationale 3: To enable the system to be calibrated.
Rationale 4: To obtain blood samples by maintaining a closed loop when monitoring and control blood flow when sampling.
Rationale 5: A haemodynamic monitoring system consists of an amplifier that enhances the signal, which is then converted into a digital display and an oscilloscope trace ( Perrin 2008).
Rationale 6: To meet Trust and National Standards ( NPSA 2008a; NPSA 2008b).
Rationale 7: To meet the NMC Code of Professional Conduct ( NMC 2008).
Rationale 8: To prevent backflow of blood.
Rationale 9: To promote longevity of the line (Ewens and Jevons 2007; NPSA 2008b).
Rationale 10: To maintain patency.
Rationale 10b: To reduce risk of haemmorhage and contamination of blood samples.
Rationale 11: They may cause severe tissue necrosis as drug is delivered in a high concentration to the affected limb.
Rationale 12: To ensure they are not mistaken for venous access.
Rationale 13: To minimise blood loss if equipment becomes disconnected.
Rationale 14: To minimise the risk of infection.
Rationale 15: To remove site of infection ( Burns and Chulay 2006).
Rationale 16: To relieve the spasm and restore circulation ( Ewens and Jevons 2007).
Rationale 17: To avoid risks associated with arterial cannula ( Woodrow 2009).
Rationale 18: To manage the associated risks.
Rationale 19: According to the BNF for Children "the role of heparin flushes in maintaining patency of arterial and central venous catheters is unclear" ( BNF 2014). Current GOSH practice supports the use of heparinised saline.
Rationale 20: Heparin may be omitted in patients with severe bleeding disorders (Blackmore et al 1998; Cardinal et al 2000; Gamby and Bennett 1995; Heap et al 1997; Lua et al 1997).
Rationale 21: To maintain patient safety from air embolism.
Rationale 22: To ensure they understand the reason for the procedure and can give informed consent.
Rationale 23: To ensure that they are psychologically prepared.
Rationale 24: Well-informed children are able to develop coping strategies ( Howard R et al 2008).
Rationale 25: Well-informed parents are more likely to stay calm and to be able to support their child ( Howard et al 2008).
Rationale 26: To ensure the procedure is correctly carried out and an appropriate artery is selected.
Rationale 27: To minimise the risk of cross infection ( Pratt et al 2007; GOSH 2012a).
Rationale 28: To ensure equipment readily available.
Rationale 29: Collateral blood supply is good.
Rationale 30: It is easily palpated.
Rationale 31: There is a reduced risk of infection compared with femoral access ( Pratt et al 2007).
Rationale 32: The brachial is an end artery ( Ewens and Jevons 2007).
Rationale 33: Cannulation of the ipsilateral radial or dorsalis pedis may result in the development of digital ischaemia ( Woodrow 2009).
Rationale 34: To reduce pain and fear and to ensure the patient remains still.
Rationale 35: Topical anaesthetic may be ineffective for arterial puncture ( Howard et al 2008).
Rationale 36: To ensure adequate circulation is maintained.
Rationale 37: To maximise the success of the procedure.
Rationale 38: To provide better access.
Rationale 39: To ensure that it can be found and is suitable.
Rationale 40: To clean the skin.
Rationale 41: To prevent re-contamination of the skin ( Howard et al 2008).
Rationale 42: To avoid cardiac arrhythmias in neonates.
Rationale 43: To ensure it is not damaged and is fit for its purpose.
Rationale 44: To immobilise the vein.
Rationale 45: Inadequate skin nick may cause significant resistance to cannula insertion.
Rationale 46: To ensure cannula is correctly inserted and patent.
Rationale 47: There is a risk of puncturing the cannula and embolising the tip.
Rationale 48: To prevent clotting.
Rationale 49: To check for patency of line.
Rationale 50: To facilitate easy observation of the cannula site ( Ewens and Javons 2007; Burns and Chulay 2006).
Rationale 51: To prevent movement which may cause extravasation & phlebitis ( GOSH 2010).
Rationale 52: Attempted femoral artery cannulation may result in inadvertent femoral vein cannulation
Rationale 53: To establish baseline non invasive blood pressure in case of arterial line failure (see troubleshooting).
Rationale 54: Invasive monitoring provides more accurate blood pressure readings than non-invasive techniques, especially in the critically ill ( Perrin 2008; Ewens and Jevons 2007) Arterial recordings may be 5-10 mmHg higher than non-invasive measurement ( Singer and Webb 200; Adam and Osborne 2005).
Rationale 55: To minimise risk of sharp’s injuries.
Rationale 56: To maintain an accurate record.
Rationale 57: To ensure the haemodynamic measurements are accurate.
Rationale 58: To ensure the nurse caring for the child has personally ensured that the measurement is accurate.
Rationale 59: A change in position can affect the accuracy of calibration.
Rationale 60: Any intervention with monitoring system can affect the accuracy of measurement.
Rationale 61: It is used for accurate measurement of intra-arterial pressures.
Rationale 62: The child’s right atrium and the phlebostatic axis remain constant up to a 45 degree angle ( Perrin 2012).
Rationale 63: To obtain an accurate invasive pressure measurement.
Rationale 64: To maintain patient safety.
Rationale 65: To determine the size of the waveform on the display.
Rationale 66: To provide a clear arterial blood pressure trace.
Rationale 67: Optimum automatically calculates a”best fit” based on the child’s current trend.
Rationale 68: To identify which pressure is being monitored.
Rationale 69: To alert any practitioner of any complication
Rationale 70: To keep the cannula patent.
Rationale 71: To minimise potential of blood loss.
Rationale 72: To diminish the potential of blood back-flow into the monitoring system.
Rationale 73: To reduce the risk of obstruction and loss of access ( Woodrow 2009).
Rationale 74: Heparinised saline must be used with caution in patients with severe bleeding disorders (Garretson 2005).
Rationale 75: A low rate will minimise arterial trauma and the effects of interference with pressure mean recordings.
Rationale 76: Repeated use increases the potential of intra-arterial trauma, retrograde aortic flow and cerebral embolisation.
Rationale 77: It reduces the administration of unknown quantities of fluid.
Rationale 78: To check for adequate blood supply to the affected limb.
Rationale 79: To reduce risk of cannula dislodgement and maintain patency.
Rationale 80: The cannula may need to be removed.
Rationale 81: These signs indicate decreased circulation distal to arterial entry site ( Burns and Chulay 2006).
Rationale 82: These signs indicate arterial spasm ( Ewens and Jevons 2007).
Rationale 83: These signs indicate clot formation ( Burns and Chulay 2006).
Rationale 84: To maintain circulation to limb.
Rationale 85: To maintain patient comfort.
Rationale 86: To enable prompt recognition of complications.
Rationale 87: To enable early detection of complications.
Rationale 88: To minimise and stop bleeding.
Rationale 89: To prevent further dislodgement and maintain cannula.
Rationale 90: To prevent risk of retained cannula ( NPSA 2008a).
Rationale 91: To ensure it remains intact.
Rationale 92: To maintain the flow of the infusate.
Rationale 93: To avoid an occluded line.
Rationale 94: The pressure bag may be deflated.
Rationale 95: There may be a loose connection.
Rationale 96: To ensure the site remains visible, dry and intact.
Rationale 97: To detect signs of cannula related infection ( Pratt et al 2007).
Rationale 98: Antibiotics may be required.
Rationale 99: Micro organisms in the cannula may have been flushed into the body.
Rationale 100: To maximise the information obtained.
Rationale 101: To optimise treatment.
Rationale 102: There are two main methods of BP monitoring: direct and indirect. A direct BP can only be performed when the child has an arterial line in situ, but it is regarded as the 'gold standard' or 'true' BP ( Derrico 1993).
Rationale 103: To ensure accuracy of vital signs.
Rationale 104: To maintain infusion administration.
Rationale 105: To maintain the position of the catheter.
Rationale 106: Patient may have no cardiac output (pulseless electrical activity (PEA)) or low blood pressure.
Rationale 107: To exclude backflow if the child’s pressure exceeds flush pressure.
Rationale 108: The occlusion may be due to blood clot ( Burns and Chulay 2006).
Rationale 109: May traumatise vessel, release clot and damage local blood circulation.
Rationale 110: To ‘clear’ line occlusion.
Rationale 111: Changes in arterial waveform frequently reflect pathological processes, eg hypertension, valvular dysfunction and severe cardiac compromise ( Ewens and Jevons 2007).
Rationale 112: Artificial elevation in peak systolic pressure trace may be noted.
Rationale 113: To minimise distortion.
Rationale 114: Transducer no longer calibrated.
Rationale 115: To minimise catheter and limb movement.
Rationale 116: To promote vasodilation.
Rationale 117: To ensure it is switched on.
Rationale 118: To determine if equipment is faulty.
Rationale 119: To initiate repair of equipment.
Rationale 120: Other electrical equipment may produce 60 cycle interference in tracings.
Rationale 121: These signs could indicate a blockage/fibrin sheath.
Rationale 122: These signs could indicate a line malposition.
Rationale 123: To distract the child.
Rationale 124: To avoid damaging the artery.
Rationale 125: To protect patient and surrounding area from potential blood spillage.
Rationale 126: To prevent occlusion alarm.
Rationale 128: To withdraw dead space, clear the cannula and 3WT of heparin, old blood and small emboli ( Woodrow 2009).
Rationale 129: To prevent movement of infusion fluid ( Woodrow 2009).
Rationale 130: To enable sample to be taken.
Rationale 131: To prevent blood collection in the hub.
Rationale 132: Blood left in the line could cause a dampening effect on a trace if BP is measured.
Rationale 133: To check patency of arterial line for monitoring purposes.
Rationale 134: To facilitate investigation.
Rationale 135: To minimise unnecessary blood loss and avoid iatrogenic anaemia.
Rationale 136: To prevent replacement of debris, clots etc.
Rationale 137: To prevent retrograde aortic flow ( Garretson 2005).
Rationale 138: Infusion pressure must be higher than intra-arterial pressure 150-200mmHg.
Rationale 139: To seal the circuit.
Rationale 140: To avoid excess fluid administration.
Rationale 141: To prevent prolonged bleeding from site following cannula removal.
Rationale 142: To facilitate easy removal of the arterial line.
Rationale 143: Application of pressure during removal will cause pain.
Rationale 144: To reduce risk of haematoma formation.
Rationale 145: To ensure no further bleeding.
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