404FM.2 CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) USING CITRATE Target Audience: Hospital only ICU (Based on Gambro and Kalmar Hospital protocols) CRRT using regional citrate anticoagulation This is a therapy which is used in Critical Care as a supportive mechanism for those patients who have developed an acute kidney injury (AKI). AKI is characterised by a rapid reduction in kidney function resulting in a failure to maintain fluid, electrolyte and acid-base homoeostasis (Lewington and Kanagasundaram, 2011). The aim of therapy is to replace normal glomerular filtration by: Relieving hypervolaemia and maintaining fluid balance. Removing excess urea and creatinine. Correcting and maintaining metabolic and electrolyte balance. Continuous renal replacement therapy (CRRT) allows fluid and waste products to be removed while maintaining cardiovascular stability in critically ill patients who respond poorly to intense dialysis therapy, delivered over a three to four hour period. Citrate chelates calcium in the blood flowing through the filter, temporarily removing it from the clotting pathway, thereby preventing intra-filter clot formation. The citrate infused blood passes through the filter, and calcium is replaced via an infusion to the patient, thereby enabling regional anticoagulation of the filter, without systemically anticoagulating the patient. On metabolism by the liver, skeletal muscle and kidneys, each citrate molecule breaks down to release three bicarbonate ions and the remaining chelated calcium which has not passed into the effluent fluid. SET UP AND STARTING TREATMENT Before starting treatment Check the daily blood results before the start of treatment, including: Total calcium (not the corrected value) Magnesium, phosphate, potassium and bicarbonate levels Ionised calcium (arterial blood gas) Calcium levels should be corrected prior to treatment starting, as this will ensure the patient has sufficient calcium reserves for clotting, and will prevent masking of citrate accumulation signs. Potassium and magnesium correction should not delay starting the filter. APTT levels will NOT be required for citrate anticoagulation. Equipment needed 1 ST150 Prismaflex kit 1 CA250 calcium line 1 x 50 ml Luer lock syringe 1 x 5 litre bag of Prismocitrate 18/0 (citrate used as pre-dilution) 1 x 5 litre bag of Prism0cal B22 (calcium-free dialysate solution) 1 x 5 litre bag of Phoxilium (post-dilution replacement solution) 2 x 1 litre bags of 0.9% sodium chloride (priming solution) 11.3 mmol calcium gluconate in 50 ml (neat) as calcium replacement Sterile dressing pack and trolley 2 x 5 ml syringes to withdraw hep-lock, 2 x 20 ml syringes to check flow (20 ml in 6 seconds), 2 x 10 ml syringes for sodium chloride flush. Guideline 404FM.2 1 of 15 Uncontrolled if printed
Setting up and priming Switch the machine on, input the patient details, ensure accurate patient weight and haematocrit is entered. This will impact on the therapy delivery. Choose the CVVHDF option. Choose citrate-calcium via the Prismaflex syringe pump. Follow the on-screen step-by-step installation instructions. Install Prismocitrate 18/0 on the white scale (PBP = pre-blood pump). Install Prism0cal B22 on the green scale (dialysate). Install Phoxilium on the purple scale (replacement). Ensure the replacement solution indicates calcium concentration of 1.25 mmol/l. If not, call the shift leader. Prime the ST150 with 2 litres of 0.9% sodium chloride (no heparin required). Install the calcium gluconate syringe into the Prismaflex syringe pump. This should be a Terumo Luer Lock syringe. Leave the calcium line unclamped for priming by the Prismaflex machine, do not connect to the patient at this stage (risk of air embolism). Ensure fluid loss/gain limit is set to 400 ml/3 hours, this is a default setting do not change. Starting parameters Mode: CVVHDF Starting citrate dose: 3.0 mmol/l blood Starting calcium compensation: 100% Flow settings: Based on actual body weight Weight (kg) Blood flow (ml/min) Dialysate (ml/hr) Replacement post-filter (ml/hr) Actual treatment dose obtained (ml/kg/hr) 50 100 1000 400 41 60 110 1100 500 39 70 120 1200 500 35 80 130 1300 500 33 90 140 1400 500 31 100 150 1500 600 31 110 160 1600 700 30 120 170 1700 800 30 130+ 180 1800 1000 30 If the patient is severely metabolically acidotic, please see trouble shooting flow sheets for alternate action. In severely acidotic septic patients move up 2 weight brackets, more than this risks electrolytes correcting too quickly. If acidosis is not correcting fast enough, increase blood pump speed; this delivers more citrate and through metabolism releases 3 bicarbonate ions to the patient. For higher blood flow speeds, consider starting at a lower rate, then building to the required rate when the patient is haemodynamically stable. If starting at a lower blood flow speed than suggested above, the replacement and dialysate rates should still be according to the table values for the patient s weight. If starting at a lower blood flow rate, wait 1 hour after achieving the desired blood flow before measuring the calcium levels. Actual treatment dose is effluent minus 15% downtime. Guideline 404FM.2 2 of 15 Uncontrolled if printed
Connection Using a sterile pack and sterile gloves to access the vascath, ensure flow test is performed. 1. Withdraw 5 ml blood from the red vascath port to remove hep-lock and discard onto gauze (observe for clots). 2. Withdraw and replace 20 ml blood. Flow should be sufficient to withdraw 20 ml blood from the vascath in 6 seconds or less. 3. Flush with 10 ml 0.9% sodium chloride. 4. Repeat on the blue vascath port. Do not start treatment if there is a flow problem. Alert the consultant and the nurse in charge if this is the case. Vascath should be reviewed. 1. Ensure that the primed filter waits no longer than 30 minutes before connection. 2. Let the shift leader and unit doctor know the filter will be starting imminently, have fluid for a fluid challenge available in the bed space, in case of haemodynamic instability. 3. Connect red access line to the red vascath port. 4. Connect blue return line to the blue vascath port. 5. Connect yellow line to effluent bag. 6. (A) Connect calcium line to central line. (B) Alternatively if a 3 lumen vascath has been inserted the third lumen can be used for calcium only. (C) If these options aren t available a Y connector secured to the RETURN line only (as seen in the picture below) can be used. 7. Unclamp all lines. 8. START treatment. 9. Once patient is stable, increase blood pump speed to required level as above. 10. Set patient fluid removal as required. Calcium infusion only Access line Tri Lumen Gam Cath from Gambro Y connector set up (Option B) (Option C) Calcium line Return line Y connector Tape these 2 points Guideline 404FM.2 3 of 15 Uncontrolled if printed
TREATMENT MONITORING Calcium monitoring Initially And then: Post-filter ionised calcium (blood gas from haemofilter circuit) Target 0.25 to 0.50 mmol/l Patient systemic ionised blood calcium (blood gas from patient) Target 1.0 to 1.3 mmol/l Patient total calcium (not corrected calcium) Target 2.20 to 2.50 mmol/l Calcium ratio (Total Ca patient's systemic ionised Ca) Target ratio <2.5 Hourly until within normal values Hourly until within normal values After 6 hours After 6 hours 6 hourly 6 hourly 12 hourly with U&E 12 hourly with U&E 1. Ionised calcium post-filter and patient One hour after treatment is initiated and blood flow established, make two ionised calcium checks (one from the blue port on the set and another from the patient s arterial line) and alter according to the following table: Filter Ca 2+ >0.5 Filter Ca 2+ 0.25-0.5 Filter Ca 2+ <0.25 Patient Ca 2+ <1.0 Increase citrate dose by 0.5 mmol/l blood Increase calcium compensation by 10% Increase calcium compensation by 10% Decrease citrate dose by 0.5 mmol/l blood. Patient Ca 2+ 1.0-1.3 Increase citrate dose by 0.5 mmol/l blood NORMAL IDEAL VALUES Decrease citrate dose by 0.5 mmol/l blood. Patient Ca 2+ >1.3 Decrease calcium compensation by 10% Decrease calcium compensation by 10% Decrease calcium compensation by 10% Decrease citrate dose by 0.5 mmol/l blood Check post-filter ionised calcium and patient calcium levels hourly until ideal values have been established. Once two consecutive measurements are within the normal range, check the post-filter ionised calcium four times a day (every 6 hours). Increase back to hourly should values alter to outside the normal ideal values. Do not take any blood for analysis from the filter set, other than for calcium. Do not make any adjustments to therapy unless confirmed by the shift co-ordinator or ICU consultant. Check the effect of the changes to the patient by pressing the view changes button on the filter. Guideline 404FM.2 4 of 15 Uncontrolled if printed
If the citrate dose is reduced, the pre-blood pump flow and hence total effluent dose will also fall. If the total effluent dose falls below 30 ml/kg/h, increase the replacement flow until a dose of 30 ml/kg/h is achieved. If there are any changes in citrate dose or blood flow rate, hourly checks need to be carried out until 2 consecutive stable results are achieved again. 2. Calcium ratio monitoring Measure the patient s total calcium level at 6 hours by sending a U&E sample to Biochemistry. Calculate the calcium ratio by dividing the patient s total uncorrected calcium, by the patient s ionised calcium (total Ca ionised Ca). The ratio is to be calculated every 12 hours and documented on the blood results flow chart. Increasing requirements for calcium compensation could indicate citrate accumulation. Please see trouble shooting flow sheets for actions to be considered. 3. Frequency of blood tests Test U&E Potassium Glucose FBC Magnesium and phosphate Post-filter ionised calcium Patient systemic ionised calcium Patient total calcium Calcium ratio Frequency 6 hourly initially. 12 hourly when stable. At least 6 hourly. More frequent if unstable. At least 6 hourly. More frequent if unstable. 12 hourly with U&E. 12 hourly with U&E. Hourly until normal values achieved. 6 hourly when stable. Hourly until normal values achieved. 6 hourly when stable. 6 hours after filtration commenced. 12 hourly when stable. 6 hours after filtration commenced. 12 hourly when stable. Guideline 404FM.2 5 of 15 Uncontrolled if printed
PAUSING TREATMENT AND RECIRCULATION (no clotting noted in the set or lines) If the patient needs to be temporarily disconnected, it is possible to recirculate the blood through the filter to prevent clot formation. There are 2 recirculation options available: Sodium chloride recirculation after returning the blood, sodium chloride is circulated through the blood lines of the filter. The filter set will need to be re-primed before the patient is reconnected. Max 120 minutes. Blood recirculation after the patient has been disconnected (without returning the blood) the filter re-circulates blood in the filter blood lines after to reduce the chance of clotting. Max 60 minutes. N.B. If any clotting is noticed in the set or lines return of blood and recirculation must NOT be performed. In this instance STOP the treatment and prime a new set when the patient is ready to be reconnected. Sodium chloride Recirculation Procedure Gather equipment needed: o 250 ml 0.9% sodium chloride. o 1 x Y connector and 2 spikes. o Dressing pack and trolley. o 4 x 10 ml syringes (2 to withdraw blood and 2 to flush vascath). o 2 x 10 ml 0.9% sodium chloride ampoules. o 2 x 2.5 ml syringes and heparin for hep-lock procedure, and 2 bungs. o Equipment as indicated for priming and connection. Press stop. Stop the calcium infusion and disconnect. Select Recirc option on the stop screen. Select Sodium chloride Recirc option on the recirculation options screen. Follow the on screen instructions exactly: o Hang the 250 ml bag of sodium chloride on the priming hook, connect the Y connector to the sodium chloride with the spike and prime the Y connector with sodium chloride. o Using the dressing pack and ANTT, disconnect the access line from the patient and connect the access line to the 250 ml sodium chloride bag via the Y connector. Enter the desired blood return settings. o Return the blood to the patient. o Flush the disconnected vascath port, hep-lock (except in heparin-induced thrombocytopenia (HIT) patients) and cap. o Enter the desired recirculation rate (can be changed during recirculation). o Disconnect the return line from the patient and connect the return line to the sodium chloride bag and begin recirculation. o Flush the newly disconnected vascath port, hep-lock (except in HIT patients) and cap and label the vascath, document the time and details on the haemofilter observations chart. When you are ready for reconnection: o Prepare a new calcium syringe and calcium line. o Stop recirculation. o Clamp the Y line. Using ANTT, disconnect the access line and reconnect it to a new spike, spike a 1 litre bag of sodium chloride and hang this on the priming hook. o Connect the return line to a new empty prime collection (effluent) bag. o Change the calcium syringe and line, prime the calcium line. o Prime the filter set. o When the machine has passed the Prime Test, reconnect the patient as per Connection on page 3. o Document the time and details on the haemofilter observations chart. Guideline 404FM.2 6 of 15 Uncontrolled if printed
Blood Recirculation Procedure Gather equipment needed: o Y connector o Spike o 100 ml 0.9% sodium chloride bag o Dressing pack and trolley o 4 x 10 ml syringes (2 to withdraw blood and 2 to flush vascath) o 2 x 10 ml 0.9% sodium chloride ampoules o 2 x 2.5 ml syringes and heparin for hep-lock procedure, and 2 bungs o Equipment as indicated for connection Press stop. Stop the calcium infusion and disconnect. Select Recirc option on the stop screen. Select Blood Recirc option Follow the on screen instructions exactly: o Hang the 100 ml bag of sodium chloride on the priming hook, connect the Y connector to the sodium chloride with the spike and prime the Y connector with sodium chloride. o Using the dressing pack and ANTT, disconnect the access line from the patient and connect the access and return lines to the 100 ml sodium chloride bag via the Y connector. Repeat with the return line. o Flush, hep-lock (except in HIT patients), cap and label the vascath. o Select Start Recirc o Document the time and details on the haemofilter observations chart. When you are ready for reconnection: o Prepare a new calcium syringe and calcium line. o Stop recirculation. o Select Change Syr + Line install a new calcium syringe and line. o Reconnect the patient as per Connection on page 3. o Document the time and details on the haemofilter observations chart. STOPPING TREATMENT & DISCONNECTION There are 2 options: End Treatment to terminate the current treatment; or Change Set if the circuit has expired or clotted. End Treatment Gather equipment needed: o Dressing pack and trolley. o 4 x 10 ml syringes (2 to withdraw blood and 2 to flush vascath). o 2 x 10 ml 0.9% sodium chloride ampoules. o 2 x 2.5 ml syringes and heparin for hep-lock procedure, and 2 bungs. o 2 appropriate bin liners and closure. Press stop and select End Treatment If there is no clotting evident in the set or lines, blood can be returned to the patient by pressing Return Blood. Do NOT return blood if clotting is evident or the Filter is Clotting alarm has sounded. Follow the instructions on the screen exactly: o Clamp all lines and the vascath. o Using a dressing pack and ANTT disconnect access and return lines. o Flush, hep-lock (except in HIT patients), cap and label the vascath. o Select Unload note the fluid removal on the treatment complete screen. o Discard the set, calcium syringe and line as per body fluid and drug disposal protocol. o Document the time and details on the haemofilter observations chart. Guideline 404FM.2 7 of 15 Uncontrolled if printed
Change Set: Proceed as per End Treatment; however after disconnecting the patient, re-load a new set, continue the same treatment and proceed as per Connection on page 3. TROUBLE SHOOTING Please see attached trouble shooting flow sheets for details. Metabolic acidosis Most patients in renal failure will have a degree of metabolic acidosis prior to commencing CVVHDF; this should improve with treatment over a period of up to 2 to 4 hours. If there has been no improvement OR the patient is profoundly acidotic on commencement of treatment, consider: 1) Increase the blood pump speed to deliver more citrate to the patient. Each citrate molecule metabolises to 3 bicarbonate ions which will act as a buffer. 2) If there a problem with the lactate or solute clearance, increase the replacement rate to 2.2 litres. This will deliver more bicarbonate to the patient, increase the convection, and increase the clearance of medium and large molecules, increase the solute drag, and increases haemofiltration. NB. Monitor electrolyte balance. 3) If there is no problem with lactate or solute clearance, reduce the dialysate flow by 50%. This will clear less citrate, so allow more citrate to reach the patient. This will however reduce molecule clearance, again monitor electrolyte balance. 4) Give systemic sodium bicarbonate to the patient. Metabolic alkalosis Consider: 1) Double baseline dialysate flow rate, clears more citrate, so less citrate therefore bicarbonate will reach the patient. This will increase the solute clearance, monitor electrolyte balance. 2) Reduce the blood pump speed to reduce the amount of citrate to the patient. These changes may affect the solute clearance and filter life, and should not be undertaken without checking with the shift leader or ICU consultant. What should I do to increase solute clearance? Small molecules such as urea and potassium will respond to moving the patient up to the next weight bracket, this will increase diffusion. Larger molecules such as vitamin B 12, beta 2 microglobulin, and septic mediators, will respond to increasing the replacement rate, this will increase convection. What if the patient s calcium compensation is high? There are many reasons for increased calcium requirements, however if the calcium compensation is above 150%, the patient ionised calcium is below 1.0 and the calcium ratio is greater than 2.5, this could indicate citrate accumulation. Citrate accumulation occurs when the citrate is not metabolised by the kidneys, skeletal muscle and liver, therefore the chelated calcium is not released back into the patient s circulation. The primary concern in this case is to further supplement the patient s calcium level, and to reduce the citrate load to the patient. Please see attached trouble shooting flow sheets for details. Guideline 404FM.2 8 of 15 Uncontrolled if printed
Solute Clearance Increasing solute clearance depends on the size of the molecule to be cleared. Small molecules are cleared through diffusion; medium and larger molecules are cleared through convection. Moving the patient up to the next weight bracket Increases diffusion Increases clearance of small molecules (urea, creataine, potassium and citrate). Increases hemodialysis Increasing the replacement rate Increases convection Increases clearance of medium and large molecules Increases solute drag Increases hemofiltration Abass M (2015), Kamc crrt training - Prismaflex CRRT Medical Overview February 2015, [Online], https://www.slideshare.net/mobile/mhabbassabbass/kamc-crrt-training?qid=4d49c6d5- c46f-437a-960a-ecd93a3e4c1d&v=&b=&from_search=4 (restricted access) Guideline 404FM.2 9 of 15 Uncontrolled if printed
What happens when the patient weight bracket is changed? Number of weight brackets moved up Weight (kg) Blood flow (ml/min) Dialysate (ml/hr) Replacement post-filter (ml/hr) Actual treatment dose achieved (ml/kg/hr). Effluent dose 15% down time. Citrate load Starting 70 120 1200 500 35 11.6 point 1 70 130 1300 500 38 12.8 Gives more citrate to the patient, which will metabolise to release 3 bicarbonate molecules per calcium citrate complex. This will help to ph Citrate clearance and solute clearance. Will work well for removing Ur Cr and K, but won t help ph as much 2 70 140 1400 500 40 14 Gives even more citrate to the patient, which will metabolise to release 3 bicarbonate molecules per calcium citrate complex. This will help to ph Further citrate clearance and solute clearance. Will work well for removing Ur Cr and K, but won t help adjust ph as much 3 70 150 1500 600 43 14.9 4 70 160 1600 700 47 15.8 5 70 170 1700 800 51 16.8 6 70 180 1800 1000 56 17.5 Although more citrate is infused, a greater amount of the citrate calcium complex is excreted via the dialysate, this is demonstrated by the calcium syringe rate increasing to compensate. Guideline 404FM.2 10 of 15 Uncontrolled if printed
What happens when I increase just the blood pump speed? Weight (kg) Blood flow (ml/min) Preblood pump (ml/min) Dialysate (ml/min) Replacement (ml/min) Actual treatment dose (ml/kg/hr) Citrate load 70 120 1200 1200 500 35 11.6 70 140 1400 1200 500 38 14.4 70 160 1600 1200 500 40 17.6 70 180 1800 1200 500 42 20.2 This has the effect of increasing the amount of citrate getting to the patient which enables the citrate complex to be broken down to release the calcium and bicarbonate. You can see changes in the citrate load and effluent dose by pressing the View Changes button on the screen that appears when you change the flow rates. Baxter Prismaflex Learning Website, https://prismaflex71.baxter.semcon.com/en-gb/ Guideline 404FM.2 11 of 15 Uncontrolled if printed
Metabolic Acidosis with Calcium Ratio <2.5 and Patient Ionised Calcium >1 improvement to acidosis on standard filter settings, despite reversible causes being addressed; discuss with ICU consultant and shift leader and consider: In severe acidosis with marked electrolyte derangement, consider moving up 2 weight brackets MAX. If ph is slow to correct, increase the blood pump speed. Increase blood pump speed by 20 ml This delivers more citrate to the patient. (Do NOT move up patient weight bracket.) Max 3 times or 200 ml whichever is less Continue current settings review hourly until calcium readings are stable on 2 consecutive readings Is improvement shown after 1 hour? If the blood pump speed has been increased 3 times, or reached 200 ml with no improvement Is there a lactate or solute clearance problem? Increase replacement flow to 2.2 litres max. This will deliver more bicarbonate to the patient and increase solute clearance. This can increase the chance of clotting in the return line, be alert for alarms. Reduce dialysate flow by 50% This clears less citrate, so allows more citrate to reach the patient. N.B This will also reduce the solute clearance, so watch K + etc. Is improvement shown after 1 hour? Is improvement shown after 1 hour? OR OR Consider systemic sodium bicarbonate infusion Consider systemic sodium bicarbonate infusion Continue current settings review hourly until calcium readings are stable on 2 consecutive readings When ph is back in range, reduce the replacement rate by 500 ml until baseline rate is achieved. Continue current settings review hourly until calcium readings are stable on 2 consecutive readings Each citrate molecule metabolises to release 3 bicarbonate ions; this is why we aim to get more citrate to the patient. These interventions will have differing effects on solute clearance, and the potential for citrate toxicity. Please remember hourly post-filter ionised calcium and patient ionised calcium checks until these values are within normal limits. Watch for signs of citrate toxicity: ionised Ca ++ (below 1.0), calcium compensation, calcium ratio >2.5 Ensure the shift leader and ICU consultant remain informed of the outcomes to any changes made. Guideline 404FM.2 12 of 15 Uncontrolled if printed
Calcium Ratio >2.5 and Patient Ionised Calcium <1 If calcium ratio is above 2.5 and the patient ionised calcium falls below 1.0 despite calcium correction; discuss with ICU consultant and shift leader and consider: Consider giving additional IV calcium supliment patient calcium level. Decrease blood pump speed by 20 ml increments until calcium ratio and ionised calcium correct, or blood pump speed reduced to 100 ml. This reduces the citrate load to the patient. Continue current settings review hourly until calcium readings are stable on 2 consecutive readings Is improvement shown after 1 hour? If the blood pump speed has been decreased, or reached 100 ml with no improvement Is there citrate accumulation with acidosis? Increase replacement flow to 2.2 litres max. This will increase hemofiltration and solute clearance. This can increase the chance of clotting in the return line, be alert for alarms. Aim post filter Ca + of 0.4 0.5 mmol/l. Decrease citrate dose in 0.2 mmol/l increments until this is achieved. If total effluent dose falls below 30 ml/kg/hr increase the replacement flow until a dose of 30 ml/kg.hr is achieved. Is improvement shown after 1 hour? Post filter Ca + can be checked straight after the changes are made. Is improvement shown after post filter Ca + is corrected? Continue current settings review hourly until calcium readings are stable on 2 consecutive readings Double baseline dialysate flow This will increase citrate clearance, and solute clearance, watch electrolyte balance. Continue current settings review hourly until calcium readings are stable on 2 consecutive readings These interventions will have differing effects on solute clearance. Please remember hourly post-filter ionised calcium and patient ionised calcium checks until these values are within normal limits. Ensure the shift leader and ICU consultant remain informed of the outcomes to any changes made. Guideline 404FM.2 13 of 15 Uncontrolled if printed
Metabolic Alkalosis ph >7.45 with B.E >+5 These changes may affect solute clearance and filter life, discuss any changes with the shift leader or the ICU consultant. Rule out and treat underlying causes (i.e. prolonged vomiting, diuretic overuse, hypovolaemia and hypokalaemia) Is improvement shown after 4-6 hours of standard rate haemofiltration? Continue current settings review hourly until calcium readings are stable on 2 consecutive readings Is the alkalosis thought to be due to excess citrate accumulation? Check ionised Ca + and Ca ratio. Double the baseline dialysate rate. This will clear more citrate; it will also clear more solutes, monitor electrolyte balance. Is improvement shown after 2 hours? Reduce blood pump speed. This will reduce the citrate load to the patient, and consequently reduce the buffer delivered. These interventions will have differing effects on solute clearance. Please remember hourly post-filter ionised calcium and patient ionised calcium checks until these values are within normal limits. Ensure the shift leader and ICU consultant remain informed of the outcomes to any changes made. Guideline 404FM.2 14 of 15 Uncontrolled if printed
Title of Guideline Continuous Renal Replacement Therapy (CRRT) using Citrate Guideline Number 404FM Version 2 Effective Date July 2018 Review Date July 2021 Original Version Published February 2015 Approvals: Formulary Management Group 22nd October 2014 Clinical Guidelines Subgroup 25 th July 2018 Author/s Lucy Bull (Revised by Tracy Hadcroft May 2018) SDU(s)/Department(s) responsible for Critical Care updating the guideline Uploaded to Intranet 30 th July 2018 Buckinghamshire Healthcare NHS Trust Guideline 404FM.2 15 of 15 Uncontrolled if printed