The vascular service at Frimley Health provides surgical care of abdominal and descending thoracic aneurysms. Abdominal aortic aneursyms can be managed with either open or endovascular surgery. Infra renal and complex endovascular surgery undertaken at Frimley Park Hospital (FPH) includes fenestrated grafts (FEVAR), descending thoracic grafts (TEVAR) and relay procedures.

Paraplegia due to spinal cord ischaemia (SCI) is a recognised complication of open and endovascular thoracic aortic surgery occurring in up to 15% of patients ^[1]. The incidence in endovascular repair ranges from 0.8–8.6% ^[2]. Both surgical and patient factors contribute to the risk of developing SCI. Symptoms usually manifest in the immediate postoperative period but may be delayed for up to a week.

Risk factors associated with the development of spinal cord ischaemia (SCI)

• Long stent graft aortic coverage (>20cm)

• Previous abdominal aortic surgery (open or endovascular)

• Left subclavian artery coverage

• Emergency Case

• Perioperative hypotension

• History of peripheral vascular disease

• Chronic renal insufficiency

• Diabetes

• COPD

• Age >75

Strategies designed to reduce the incidence of SCI rely on an attempt to improve the perfusion and oxygen delivery to the cord.

• Optimise the haemoglobin preoperatively

• Shortest possible treatment duration

• Prevent Hypotension (Map >90 mm Hg)

• Preservation of perfusion to the internal iliac arteries

• Management of Cerebrospinal fluid pressure

• Staged Procedure in complex endovascular cases

• Neurophysiological Monitoring (Not available at FHFT)

Drainage of Cerebrospinal fluid is a recognised technique employed to reduce the CSF pressure in an attempt to improve spinal cord perfusion. In high risk cases (particularly open surgery) a drain may be inserted electively, and the CSF pressure managed both during and after surgery. The overall risks of drain complications in the literature is around 8% ^[3]. Both the risks and consequences of spinal cord ischaemia and drain complications are significant and many centres favour drain insertion only if symptoms of ischaemia develop.

There is no evidence that elective drain insertion reduces the risks of SCI in endovascular aortic surgery ^[4]. The risks of SCI maybe lower than the potential complications of drain insertion and the literature favours tailored drain insertion in high risk cases only ^[5]. At Frimley Park, TEVAR procedures are usually conducted in two stages in an attempt to reduce the risk of SCI developing post operatively. Drain insertion is therefore predominantly emergent.

A CSF drain (CSFD) is a catheter (specialised silicone lumbar drain or epidural catheter), which is inserted into the subarachnoid space to allow CSF drainage. It is placed to reduce the CSF pressure in an attempt to improve blood flow to the spinal cord. The catheter is placed below the level of the termination of the cord (L2-L3 or below). The catheter is taped securely to the skin to prevent dislodgement, and is connected to a manometer, and CSF collection system.

Why do we use a CSF drain:

The arterial blood supply to the spinal cord relies on the anterior spinal artery, which arises from the vertebral artery, branches from the intercostal arteries (including the artery of Adamkiewicz), which arise from the thoracic aorta, lumbar arteries that come off the abdominal aorta and branches from the internal iliac vessels (Figure 1).

Figure 1. Blood supply to the spinal cord

Perfusion pressure of the spinal cord (SCPP) is derived from the difference between the mean arterial blood pressure (MAP) and CSF pressure (CSFp).

SCPP = MAP - CSFp

Clamping or stenting the aorta reduces the blood pressure below the clamp putting the distal spinal cord at risk of ischaemic damage.

Ischaemia causes oedema of the spinal cord within the confined space of the spinal canal. By increasing the blood pressure and reducing the CSF pressure the spinal cord perfusion pressure rises with the aim of preserving cord function.

The goal of CSF drainage is to maintain SCPP above 70 mm Hg. To achieve this a CSF pressure of less than 10mm Hg and a MAP >90mmHg should be targeted.

Contraindications of CSF Drainage

• Absolute: Patient refusal

• Relative: to be weighed against the risk of developing SCI

• Abnormal clotting

• Active infection

• Raised intracranial pressure

Complications of CSF drainage

• Traumatic / bloody tap – potentially delaying surgery

• Intracranial haemorrhage

• Spinal haematoma – with paraplegia

• Infection – meningitis or spinal abscess

• Inadvertent administration of medication via the drain

• Spinal headache

• Persistent CSF leak

• Retained catheter tip

• Arachnoiditis

Elective Drain Insertion and Management

• Full asepsis with insertion by Consultant Vascular Anaesthetist

• Awake

• Sitting or Left Lateral decubitus at L3/4 or L4/5 Level

• LOR Technique to identify epidural space

• Remove LOR syringe and slowly advance (0.5-1cm) the 16G Tuohy needle until CSF flows freely

• Insert catheter leaving 5-7cm in situ

• Confirm free drainage and easy aspiration through the catheter

• Secure with LockIt devices and/or transparent adhesive dressings

• Confirm CSF flows continues freely after applying dressing

• Confirm CSF flows freely after positioning on the operating table

• DO NOT USE FILTER** (it can obstruct CSF flow)

• Setup the external drainage system - Only flushless pressure transducer systems are used

• All 2 way taps in the CSF drain system should be labelled ‘CSF’ drain

• The zero level should be at the height of the heart (as with all other pressure transducers)

Complications during drain insertion

• Bloody tap during insertion: Reinsert at another level. - IV heparin should be avoided for 60 minutes

• Second bloody tap – consider abandoning procedure

• Paraesthesia on insertion – withdraw catheter until this resolves

Intraoperative Drain Management

• Target CSFP of 10 mmHg with a starting manometer height of 15mmHg

• Initiate CSF drainage at the start of the case and slowly reduce the pressure to 10mmHg by the time the stent is deployed.

• Limit the hourly drainage to a maximum of 20 mls.

• Rapid Drainage risks intracerebral haemorrhage

• Monitor and record the colour and volume of the CSF drained

• Complete the handover to ITU

Post-operative management of awake patients with a spinal drain

The highest-risk period for development SCI is during first 72-hours post graft placement.

• TEVAR repair patients should all have a planned admission to ITU.

• The patient must be managed within ITU not as ‘extended stay’ in PACU

• Patient should be semi reclining with upper body angle no more than 30 degrees

• Continue CSF free drainage up to 20ml/hr– manometer level 10mmHg assuming no neurological signs.

• If free drainage is greater than 20 ml/hr – inform medical team.

• The MAP > 90mmHg, with vasopressor support if necessary

• Patients should continue to receive their normal medication including thromboprophylaxis and antiplatelets, on an individual basis, after discussion with surgeons.

Drain Removal

Spinal drain in situ – no postoperative neurology

Day 0 (day of surgery)

1. Free drainage of CSF – patient lying flat <30 degrees

2. Hourly neuro observations

Post-operative Day 1

1. No neurological deficit is detected and MAP is >90mmHG without vasopressors

2. Clamp SCD spinal drain clamped at 6.00am (12-24 hours after the procedure).

The patient should remain in bed but may sit-up.

3. Continue hourly neuro obs.

4. IF Neurological deterioration – UNCLAMP DRAIN

Post-operative Day 2

1. No neurological deficit detected with 24 hours of drain clamping.

2. Check clotting and platelet count greater than 50

3. Ensure 12 hours since last dose of thromboprophylaxis.

4. Remove drain

5. Wait > 4hrs to next dose thromboprophylaxis.

MOST COMMON IN FIRST 2 POST OP DAYS BUT may develop up to 5 days post op

Severe back pain

Sensory deficit in lower limbs

Weakness or complete loss of motor function (uni or bilateral)

Loss of bladder control

Loss of bowel control

Suspected Intracranial Bleed

Features:

Frank blood in CSF

Drop in GCS

Pupil abnormalities

Headache

Blurred vision

Confusion

Unilateral sensory or motor impairment (upper and/or

lower limbs)

Management

Inform the vascular surgical and anaesthetic/ITU consultants

Clamp* the CSFD (CSF drain)

Organise immediate imaging** of spinal cord

Check clotting and correct coagulopathy

*CLAMPED= the near patient 3 way tap is switched to the off position OR the 3 way tap at the manometer zero is switched to off in the ‘downward’ orientation

**Imaging as discussed with Radiologist: CT aortogram, CT Head and/or MRI spine considered

Turbid Cloudy CSF

Inform Consultant Anaesthetists and Surgeons

Check insertion site

Temperature

Inflammatory markers

Send CSF for gram strain/MCS from collection bag

Discuss with Microbiology

CSF leak and postural headaches post drain removal

Inform Surgical Team

Inform Anaesthetic /ITU Consultants

Management – Conservative

Bed rest

<30 degree head up tilt

Hydration

Analgesia – for headache as per PDPH

Consider imaging

Consider blood patching

Development of post-operative neurology and spinal drain insitu

1. Adverse neurological signs – weakness, paraplegia or new paraesthesia

2. Inform anaesthetic consultant and vascular surgical consultant immediately

3. Check the insertion site for signs of inflammation, CSF leakage or pus

4. URGENT SPINAL RESUSCITATION – COPS

C – CSF drainage – lie flat reduce CSF pressure by 5mmHg, consider further stepwise reduction is CSF pressure to minimum of 5 mmHg CONSULTANT LED

O – oxygen delivery SaO2 >96% PaO2 >10 kPA Hb >100g/L

P – Pressure – ensure MAP >90mHg – consider increasing MAP >100mmHg (fluids and vasopressors)

S – Status – continue to document hourly neuro obs.

Review: Coagulation studies +/- ROTEM and platelets as indicated

Check ACT and consider protamine if heparin in preceding 6 hours

If neurology does not resolve with optimal resuscitation – consider MRI of lumbar spine

Development of Post operative When spinal drain in not insitu

1. Institute spinal resuscitation and arrange for urgent CSF drain insertion

2. CSFD inserted if no response to optimised O2 delivery and blood pressure elevation.

3. Set CSF manometer level to 10mmHg

4. Continue management as above.

1. Gaudion M. et al, Spinal Cord Injury after open and endovascular repair of descending thoracic and thoracoabdominal aortic aneursyms : A metanalysis: The Journal of Thoracic and Cardiovascular Surgery Volume 163, Issue 2, 552-564(February 2022)

2. Xue L, Luo S, Ding H, Zhu Y, Liu Y, Huang W, Li J, Xie N, He P, Fan X, Fan R, Nie Z, Luo J. Risk of spinal cord ischemia after thoracic endovascular aortic repair. J Thorac Dis. 2018 Nov;10(11):6088-6096. doi: 10.21037/jtd.2018.10.99. PMID: 30622780; PMCID: PMC6297439.

3. Plotkin A, Han SM, Weaver FA, Rowe VL, Ziegler KR, Fleischman F, Mack WJ, Hendrix JA, Magee GA. Complications associated with lumbar drain placement for endovascular aortic repair. J Vasc Surg. 2021 May;73(5):1513-1524.e2. doi: 10.1016/j.jvs.2020.08.150. Epub 2020 Oct 11. PMID: 33053415.

4. Frankort J, Mees B, Doukas P, Keszei A, Kontopodis N, Antoniou GA, Jacobs MJ, Gombert A. Systematic Review of the Effect of Cerebrospinal Fluid Drainage on Outcomes After Endovascular Descending Thoracic/Thoraco-Abdominal Aortic Aneurysm Repair. Eur J Vasc Endovasc Surg. 2023 Oct;66(4):501-512..

5. Kemp C, Ikeno Y, Aftab M, Reece TB. Cerebrospinal fluid drainage in thoracic endovascular aortic repair: mandatory access but tailored placement. Ann Cardiothorac Surg. 2022 Jan;11(1):53-55.

6. Spinal Drain Standard Operating Procedure – Imperial College Healthcare

7. A guide to the management of lumbar CSF drains – Royal Sussex County Hospital

8. Association of Anaesthetists: Regional Anaesthesia and Patients with abnormalities of coagulation

Features of spinal cord Ischaemia

Motor deficit in lower limbs (uni/bilateral)

Loss of bladder or bowel control/failed TWOC

Sensory deficit of lower limbs

Severe back pain

Spinal Resuscitation – COPS

CSF pressure – lie flat , drain CSF

Oxygen delivery – SPO2 >96%, HB >100g/l

Pressure MAP > 90mmHg

Status – hours neuro obs, correct clotting

If CSF Drain in situ

Review CSF pressure – reduce set drainage pressure by 5 mmHg

Hourly neurological assessment

Urgent surgical review consider stepwise reduction in CSF pressure to 5 mmHg

If neurology not resolving consider urgent MRI spine for haematoma

If CSF not draining

Exclude kinks and blockages

Temporary reduction in CSF pressure to

5 mmHg to check patency

Aspirate CSF – full asepsis or consider replacement (consider clotting status)

Asymptomatic blood stained CSF

Correct coagulopathy reassess CSF hourly

If CSF still blood stained after 4 hrs – urgent imaging

If no CSF drain

Call for help

Contact vascular registrar 133727 or switch

ITU/anaesthetic consultant on call via switch.

Book CEPOD cat 1

Locate spinal drain box – labelled cupboard in Theatre10

Check and correct clotting

Document neurology

Insert Lumbar CSF drain

QR code for drain video (courtesy of Dr V Fludder, Royal Sussex County Hospital.)

COMPLICATIONS OF CSFD

Suspected Intracranial Bleed

Features

Frank blood in CSF

Drop in GCS

Abnormal pupils

Headache

Confusion

Visual blurring

Unilateral sensory or motor

Impairment including arms

Management

Clamp Drain

Immediate imaging

Inform vascular and anaesthetic consultants

Consider correcting coagulopathy

Discuss with surgeons

Turbid Cloudy CSF

Inform Consultant Anaesthetists and Surgeons

Check insertion site

Temperature

Inflammatory markers

Send CSF for gram strain/MCS from collection bag

Discuss with Microbiology

CSF leak and postural headaches post drain removal

Inform Surgical Team

Inform Anaesthetic /ITU Consultants

Management – Conservative

Bed rest

<30 degree head up tilt

Hydration

Analgesia – for headache as per PDPH

Consider imaging

Consider blood patching

This guideline has been registered with the Trust. However, clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt, contact a senior colleague or expert. Caution is advised when using guidelines after the review date.

This guideline is for use in Frimley Health NHS Foundation Trust hospitals only. Any use outside this location will not be supported by the Trust and will be at the risk of the individual using it.

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