Epidural Anesthesia (EA)

Epidural Anesthesia – Technique

Epidural anesthesia, also known as EA, EPi, spinal anesthesia, or epidural, is a form of regional anesthesia involving the injection of a local anesthetic into the epidural space. The anesthetic is typically injected through a catheter inserted via a slightly thicker needle, which is about 9 cm long. The anesthesia is used for anesthesia in the lower half of the body and for certain pain indications, such as labor pain. The epidural needle is usually placed using the “Loss-of-Resistance” technique, followed by the insertion of a catheter into the epidural space via the needle. The anesthesia is administered with a bolus dose and full dose, followed by continuous infusion. Local anesthetics alone or in combination with opioids and/or adrenaline are used for anesthesia. Injection of the local anesthetic is only done through the catheter placed in the epidural space.

Indications

• For regional anesthesia in surgeries on the lower half of the body, such as peripheral vascular surgery, low abdominal surgery, or orthopedic surgery.
• For combined anesthesia in surgeries on the lower half of the body under general anesthesia.
• Postoperative pain relief after surgery, such as abdominal surgery.
• Labor analgesia.
• Pain relief in the lower half of the body, such as ischemic pain.

Technique for Epidural Puncture

The patient is positioned for the block either sitting or lying down. The puncture and administration of the epidural are done under sterile conditions. For urological surgery and C-sections, it is usually much easier to administer the epidural with the patient sitting rather than lying down. For orthopedic surgery, the epidural is usually administered with the patient lying down. The back is cleaned and draped sterilely. In the lying lateral position, it is very important to have maximum flexion in the lumbar area and the patient positioned far out on the edge of the table, often requiring an assistant to help and adjust the position as needed.

Typically, the “Loss of Resistance” (LOR) technique is used, with puncture performed with a saline-filled syringe (5-10 ml) with low resistance. The syringe can also be air-liquid filled (5:1 ml). An alternative to the LOR technique is the “hanging drop” technique, where a drop hangs from the epidural needle without a stylet. The drop is sucked in when the epidural space is penetrated. This technique is best suited for the patient sitting upright. Position the patient sitting or lying down. For labor epidurals, it is much easier to position the patient sitting than lying down. For labor epidurals, it is generally appropriate to use the medial technique. The catheter should be relatively easy to insert into the epidural space; significant resistance suggests incorrect positioning.

Median Technique

Puncture with a 70-90 degree angle of the needle to the skin plane and a 20-40 degree angle in the cranial direction. Always support the back of your hand or knuckles against the patient’s back during the puncture. Two fingers hold the wings of the epidural needle during insertion. Loss of resistance usually occurs at 4-7 cm from the skin plane when the needle is inserted with great caution. Significant force may be required during injection but always with good control to prevent sudden penetration. You should never “slip” with the needle.

Lateral Technique

Puncture 1-2 cm from the midline between the spinous processes, slightly upwards at 70-90 degrees to the skin plane and 30-50 degrees in the cranial direction.

Contraindications

• Severely deranged coagulation
• The patient does not want EA
• Skin infection at the puncture site
• Previous EA or spinal complications
• Neurological symptoms of peripheral origin

Relative Contraindications

• Neurological dysfunction
• Spinal tumor, spinal stenosis, or recent spinal trauma
• Sepsis
• Patients with altered consciousness
• Tattoo at the puncture site

Coagulation Tests

• APTT should be normal
• PT/INR value should be < 1.4
• PT/INR value between 1.4 and 1.6 can be accepted when PLT > 100, if there is a comfort benefit
• PT/INR value between 1.6 and 1.8 or PLT 50-100 can be accepted if there is a morbidity benefit
• With PT/INR > 1.8, or PLT 30-50, EA is doubtful and may be considered if there is a mortality benefit
• Spinal anesthesia has fewer bleeding complications than EA.
• If PT/INR > 1.4 or PLT < 100, adjust coagulation first.

Puncture Level

• Thoracotomy Th 6-7
• High laparotomy Th 8-9, Th 10-11
• Major laparotomy Th 10-11
• Low laparotomy Th 10-L1, L1-L2, L2-L3.
• Nephrectomy Th 8-10
• Hip, knee surgery L1-L2

Landmarks

• Spina scapulae T3
• Angulus scapulae T7
• Crista iliaca L4

Sensory Assessment – Coverage

• Th 1 – sternal angle
• Th 4 – nipple line
• Th 8 – costal margin
• Th 10 – umbilical level
• Th 12 – groin

The Bromage Scale controls the degree of motor blockade with grading 0-3

• 0 = can lift the leg with an extended knee
• 1 = can bend at the knee joint
• 2 = can bend at the ankle joint
• 3 = cannot bend at the ankle joint, paralysis

Monitoring

• VAS scale
• Blood pressure and pulse, leg movement every 4 hours
• Sedation level and respiratory rate once per hour for the first 6 hours (fentanyl, sufentanil) or 12 hours (morphine) at startup. With dose change/bolus, check every 2 or 4 hours
• Then checks every four hours.

If the Filter Has Detached

Sterile gloves, clean the catheter with 70% alcohol, air dry, cut off 5 cm of the catheter with sterile scissors, fill a new filter with local anesthetic, connect the new adapter and new filter to the catheter, and secure well, e.g., with Tegaderm and “button”.

Removal of EPi Catheter (Removal)

• The patient usually does not need sedation
• Clean the insertion site with alcohol.
• Check the catheter tip after removal
• Keep the urinary catheter for 6 hours
• Keep the IV line for 6 hours
• Continue checks for 4 hours
• Wait at least 2 hours before restarting anticoagulation

EA and Anticoagulation

• LMWH > 5000E/40 mg – at least 24 hours before EPi placement
• LMWH 2500-5000 – given no later than 10 hours before puncture/manipulation
• From EPi puncture/manipulation to LMWH administration – at least 2 hours
• Heparin IV – wait 3 hours + new APTT
• Single therapy low-dose ASA and/or NSAIDs – for comfort benefit
• High-dose ASA – for morbidity benefit
• ASA/Plavix – for mortality benefit
• Plavix should be discontinued 5 days/High-dose ASA 7 days/Low-dose ASA 3 days

Drugs Administered in Epidural

Bolus Dose

• Ropivacaine (Naropin) 2 mg/ml 4-6 ml thoracic, 6-12 ml lumbar
• Mepivacaine (Carbocaine) 2 mg/ml, 4-6 ml thoracic, 6-12 ml lumbar
• Fentanyl 20-50 μg, Sufentanil 10-20 μg, Morphine Special 2-3 mg

Maintenance Treatment with Epidural (Continuous Infusion)

• Breivik’s mixture (Bupivacaine (Marcaine) 1.0 mg/ml + Fentanyl 2 μg/ml + Adrenaline 2 μg/ml) bolus 2-6 ml, continuous infusion 6-14 ml/h.
• Ropivacaine (Naropin) 2 mg/ml, bolus 2-6 ml, continuous infusion 4-6 ml/h thoracic, 6-12 ml/h lumbar
• Mepivacaine (Carbocaine) 2 mg/ml, bolus 2-6 ml, continuous infusion 4-6 ml/h thoracic, 6-12 ml/h lumbar

Epidural Anesthesia – Drugs and Dosing

Test Dose When Starting Epidural

A test dose of a local anesthetic is given to rule out spinal or intravascular catheter placement. The test dose is 2-3 ml of Marcaine 5 mg/ml, Narop 2 mg/ml, or Carbocaine 20 mg/ml. Observe the patient after the test dose and monitor pulse and blood pressure for at least 5 minutes. If the patient is awake, ensure they can move their legs and arms freely. Also, check with cold if the test dose causes sensory impairment. Adrenaline added to the test dose may indicate intravascular catheter placement if there is an increase in heart rate.

Morphine epidurally can be given intermittently or continuously. The usual frequency is three times a day. Normal dose: Morphine 4 mg x 3. Continuous morphine can be given in a concentration of 0.03-0.05 mg/ml. Sufentanil is given in a concentration of 0.25-1 μg/ml.

Epidural for Postoperative Pain Relief

Epidural Anesthesia for Postoperative Analgesia

Epidural Opioids

Registered drugs for epidural use in Sweden are Morphine Special (morphine) and Sufentanil (sufentanil). Fentanyl (Fentanyl) is also used epidurally. The drugs are administered continuously in infusion or intermittently in boluses, 3-4 times a day. Morphine can be given three times a day or in continuous infusion.

Dosage

• Morphine 3-4 mg x 3 in EPi. Initially, if needed, up to 5 mg of morphine hydrochloride can be given. If necessary, a dose of 2-4 mg morphine hydrochloride can be given when the effect of the first dose diminishes, usually after 6-24 hours.
• Fentanyl 2 μg/ml, 4-12 ml/hour in continuous infusion with or without a local anesthetic.
• Sufentanil 1 μg/ml, 8-16 ml/hour in continuous infusion with or without a local anesthetic. Sufentanil can also be given in bolus without a local anesthetic, 25 μg epidurally x 3-4.

Patient Checks During Epidural Anesthesia

• Pulse and blood pressure every 4 hours
• Pain intensity (VAS) every 4 hours
• Motor function in arms and legs (according to Bromage) every 4 hours
• Insertion site check once per shift
• Respiratory rate every 4 hours if opioids are added
• Sedation level every 4 hours if opioids are added.

The above checks can be performed every 6 hours after one day without dose increase. Additional checks 10 and 30 minutes after increasing the infusion rate or epidural bolus dose. Additional checks 30 and 60 minutes after reactivating the EPi. Extra checks twice per hour for 2 hours if sedative or respiratory depressant drugs are added. Dose increases and bolus doses are only given after consultation with a pain nurse or anesthesiologist. The equipment is replaced after 3 days.

Motor Function According to Bromage Grading 0-3 (Four-Grade Scale)

0: Full movement in hip, knee, and foot
1: Can move knee and hip joints, but cannot lift leg
2: Can move the ankle joint
3: Cannot move knee or ankle joint

Arm Motor Function

0: Normal motor function in arms
1: Weakness in arms

Sedation Level

0: Fully awake
1: Drowsy, lightly sedated
2: Sedated but arousable
3: Deeply sedated, not arousable
S: Sleeping naturally

Nausea

0: No nausea
1: Untreated nausea
2: Treated nausea
3: Vomiting

Itching

0: No itching
1: Untreated itching

2: Treated itching

EA and Anticoagulant Use Rules

• At least 10 hours between the given LMWH (Klexane or Fragmin) and EPi placement or adjustment of catheter position.
• EPi is removed > 2 hours before or > 10 hours after the given LMWH.
• Monitor motor function (Bromage) after 6, 8, and 12 hours after removing the epidural catheter. Document!
• The urinary catheter should remain in place for 6 hours after removing the epidural catheter.

EA Complications

Epidural hematoma is a rare but serious complication that requires immediate management. Symptoms: Back pain and sometimes radiating pain to the legs and increasing paralysis in the legs. Epidural abscess is another serious complication that requires immediate management. Symptoms: Fever, general malaise, back pain, and increasing paralysis in the legs.

If the above complications are suspected, the EPi infusion should be stopped, and an anesthesiologist should be contacted immediately!

Epidural Anesthesia (EPi) for Pain Management

Epidural Anesthesia for Postoperative Analgesia

EA and Anticoagulation

At least 10 hours between the given LMWH (Klexane or Fragmin) and EPi placement or adjustment of catheter position.

EPi is removed at least 2 hours before or at least 10 hours after the given LMWH. Monitor motor function (Bromage) after 6, 8, and 12 hours after removing the epidural catheter. Document! The urinary catheter should remain in place for 6 hours after removing the epidural catheter.

EA Complications

Epidural hematoma is a rare but serious complication that requires immediate management. Symptoms: Back pain and sometimes radiating pain to the legs and increasing paralysis in the legs. Epidural abscess is another serious complication that requires immediate management. Symptoms: Fever, general malaise, back pain, and increasing paralysis in the legs.

If the above complications are suspected, the EA infusion should be stopped, and an anesthesiologist should be contacted immediately!

PCEA (Patient-Controlled Epidural Anesthesia)

Involves continuous infusion plus patient-controlled bolus doses or intermittent infusion with only bolus doses epidurally, allowing the patient to control the treatment as desired in the form of small bolus doses. PCEA is administered epidurally with the goal of providing better pain relief with smaller total doses compared to a continuous constant infusion. The method allows the patient to control the treatment based on their activities, mobilization, and need for pain relief. The method levels out the large inter-individual differences between patients in their need for postoperative pain relief. PCEA is usually used for 2-4 days after medium and major surgical procedures and for labor analgesia. PCEA is well-suited for labor analgesia and has been shown to provide better pain relief compared to conventional EPi. For labor analgesia, PCEA can be administered either as self-administered bolus doses or as continuous infusion plus PCEA. When setting up only bolus doses, these are given in larger doses than with combined continuous infusion with PCEA, e.g., 5 ml instead of 2 ml per dose.

Risk groups include elderly patients, severely overweight patients, patients with respiratory insufficiency, severely debilitated or confused patients. For labor EPi, the primary risk groups are severely overweight patients and patients with preeclampsia.

Commonly used pumps are GEM-star, CADD, or Deltec.

Standard Infusion PCEA

Continuous infusion of 4-10 ml/h. Bolus dose 2 ml, lockout time 10 minutes, and maximum number of bolus doses per hour set at 4. At a maximum infusion rate of 10 ml/h with a maximum of 4 presses, a total dose of 18 ml/h is given, which is calculated as the highest allowed dose.

Some Suggestions for Combination Treatment with PCEA

• Bupivacaine (Marcaine) 1.0 mg/ml + Fentanyl 2 μg/ml + Adrenaline 2 μg/ml. Dosage: 4-10 ml/hour, bolus dose 2 ml.
• Ropivacaine (Naropin) 2 mg/ml, + Sufentanil 1 μg/ml, 3-10 ml/hour, bolus 2 ml during the operative day. The next morning, you can switch to Narop 1 mg/ml + Sufentanil 0.5 μg/ml to allow patient mobilization according to the surgeon’s order. This infusion can continue for a few more days.
• Ropivacaine (Naropin) 2 mg/ml + Sufentanil 1 μg/ml + Clonidine (Catapres) 3 μg/ml. 3-10 ml/hour, bolus 2 ml.

Labor EA with PCEA

• Bupivacaine (Marcaine) 0.6 mg/ml + Sufentanil 0.5 μg/ml, continuous infusion of 5 ml/hour, bolus 5 ml. Lockout time 30 minutes.

During treatment in the postop/ICU/labor ward, the number of requested bolus doses, the number of delivered doses, and the total given dose are noted and documented. The goal with PCEA is VAS < 4 and 1-2 bolus doses per hour. On the ward, it is important to monitor and check every four hours for VAS, respiratory rate, sedation level, nausea, itching, bladder function. Additional checks must be made if doses are increased, with checks every 30 minutes for two hours. If pain relief is insufficient, loading doses can be given every 10 minutes until good pain relief is achieved. If the number of PCEA doses exceeds 3 per hour, the continuous infusion is increased. If pain relief is insufficient at the maximum given dose, consider adjuvant pain treatment or replacing the epidural.

When treating patients with mild preeclampsia, coagulation tests should be checked no later than 6 hours before placing an EPi. In severe eclampsia, these tests (PT/INR/APTT/PLT) should not be older than 2 hours.

Thoracic Epidural Block (Ultrasound-Guided)

Indication: Upper laparotomies. Th6-Th12.

Patient position: Sitting or lying in the lateral position.

Transducer: 8-12 MHz, linear or curved probe (transducer).

Probe position: First place the probe in the paramedian position centrally over the spine against the upper part of the back. Then angle the probe in a paramedian sagittal section.

Puncture needle: 18 G epidural needle Tuohy needle.

Nerve stimulation response: None.

Set depth in ultrasound image: 5-8 cm.

Local anesthetic: First anesthetize locally in the skin with 2 ml Carbocaine 1% or Xylocaine 1%. For the epidural block itself, use, for example:

• Carbocaine 10 mg/ml (1%) 6-10 ml.
• Narop 5 mg/ml (0.5%) 4-6 ml.
• Bupivacaine 5 mg/ml (0.5%) 4-6 ml.

Ideal image: Th 8-Th 9, Th 9-Th 10, Th 10-Th 11. Visualize the spinous process in the midline, lamina, and transverse process, ligamentum flavum, and dura.

Note the anatomy: Lamina, interlaminar space, ligamentum flavum, posterior dura, ribs, pleura.

Technique: Initiate in the midline, then angle the probe down sagittal paramedian. Visualize first two transverse processes, then ligamentum flavum between two laminae (2-3 cm in). The dura lies just below. The distance to the ligamentum flavum can be measured with ultrasound (normally 3-5 cm).

Use the In-plane technique with puncture paramedian about 1 cm from the midline. Continue using the Loss-of-Resistance technique (LOR). Insert the epidural needle under the probe’s head laterally from the target. Identify the space between two laminae. The spinous process appears as rounded hypoechoic consolidations. Between and under these lies ligamentum flavum between two laminae and below that, the dura. Note the distance between ligamentum flavum and the dura. The ligamentum flavum should be penetrated with LOR. Perform as few injections as possible, preferably only one.

Warning: More difficult in obese patients. The dura may be difficult to distinguish from ligamentum flavum. The sitting position is preferred, but debilitated or heavily pharmacologically affected patients should lie in the lateral position. Naturally, avoid puncturing the dura. An assistant should monitor the patient from the front. Aspirate before injection. Use small repeated doses during the block.

Video link:

Knudsen’s Test for accidental dura puncture

Knudsen’s test is a simple bedside test that can detect the presence of cerebrospinal fluid. It can be used when there is suspicion of a spinal puncture of an EPi catheter or a skull base fracture with cerebrospinal fluid leakage. A cotton swab or compress is used, and fine strokes are made with colored chlorhexidine solution. Then, the fluid to be examined is applied to the swab. If a color change to red occurs, cerebrospinal fluid is present in the sample, and the test is positive. The last image shows the result of a test with saliva from a patient with a skull base fracture and cerebrospinal fluid leakage. The comparison paper swab is soaked with normal saliva.

• Knudsen K. Coloured chlorhexidine cotton pads may help to identify cerebrospinal fluid during epidural or spinal anaesthesia. Acta Anaesthesiol Scand. 2006 Jul;50(6):685-7. doi: 10.1111/j.1399-6576.2006.01046.x. PMID: 16987362.

Spinal Anesthesia and Anticoagulation

Link to Recommendations for discontinuation of anticoagulants before neuraxial block, epidural, and spinal. Click here! 

Postdural Puncture Headache – PDPH (Post Dural Puncture Headache)

Definition

PDPH is defined according to international classification as a posture-dependent headache that occurs within 5 days after a dural puncture and resolves spontaneously within a week or within 48 hours after an epidural blood patch. It is also associated with neck stiffness, tinnitus, hearing changes, photophobia, and nausea (1).

Background

After puncture of the dura, the hard outer membrane of the brain, a cerebrospinal fluid leak into the epidural space can occur. This can cause intracranial hypovolemia, with tension in cranial structures. Headache can develop, but the exact mechanism of the symptoms is not well understood. The intracranial hypovolemia can lead to cranial nerve involvement as well as venous dilation and, consequently, the risk of developing a subdural hematoma.

The severity of the headache is influenced by the needle’s gauge and design, the patient’s age and gender, with the highest risk in young women after puncture with a large needle. Obstetric patients are therefore a risk group due to their age, gender, and the frequency of epidural anesthesia during childbirth. The risk of PDPH after puncture with a 27 G pencil point spinal needle is estimated to be between 0-2%, while the risk of PDPH after accidental puncture with a 16-18 G epidural needle is 45-80% (2, 3). The incidence of accidental dural puncture during labor epidural anesthesia is approximately 1% (4).

Symptoms

The typical symptoms consist of severe posture-dependent headache. It occurs in 90% of cases within 3 days after the puncture (2, 5). The headache is usually frontal but can also be in the neck with radiation to the shoulders. The headache worsens in an upright position and is significantly relieved when lying down. Nausea, dizziness, tinnitus, hearing impairment, and photophobia are relatively common symptoms (2, 4).

Differential Diagnosis

Intracranial mass effect (e.g., hemorrhage, tumor), cerebral venous thrombosis, migraine, infectious meningitis, tension headache, preeclampsia, anemia, Sheehan’s syndrome, Posterior Reversible Encephalopathy Syndrome (PRES) (2, 3, 6). Prognosis In most cases, the symptoms resolve spontaneously within a week (2). However, chronic symptoms may also occur. Complications such as cranial nerve involvement and subdural hematoma can occur (6, 7). In one case series, the incidence of subdural hematoma was 0.026% in an unsorted obstetric epidural anesthetized population and 1.1% (1 in 87) in the group where dural puncture was confirmed during the placement of spinal anesthesia (8).

Treatment

Many different treatments have been attempted to relieve this intense headache. Professional support, careful explanation of the symptoms, and follow-up are important. Although the symptoms are relieved when lying down, bed rest has not been shown to affect the duration (2). Avoiding dehydration, providing analgesics, triptans, antiemetics, and acupuncture can relieve symptoms but rarely provide complete relief. These methods can be attempted in cases of mild symptoms and/or contraindications to blood patch treatment. However, some effect has been shown from prophylactically administered cosyntropin IV and epidurally administered morphine (9, 10). The most effective treatment so far is the epidural blood patch.

Treatment of Post Dural Puncture Headache

Treatment of PDPH with Epidural Blood Patch

The method involves an anesthesiologist injecting 20 ml of autologous blood into the epidural space at the same level as the dural puncture, or an interspace below. Theoretically, this creates an immediate increase in volume and pressure in the spinal canal, followed by a reduction in tension in intracranial structures. This leads to a rapid reduction in the headache. The blood then spreads relatively quickly in the epidural space, mainly in the cranial direction. The blood forms a clot at the tissue damage in the dura and seals the hole (2, 3, 11). The epidural blood patch was first described in the 1960s, and much of the knowledge about the treatment is based on case reports and retrospective studies. There are divergent recommendations regarding the volume of blood injected, the timing of the treatment, and whether prophylactic/therapeutic treatment should be applied (2, 3, 12, 13). There is some support that therapeutic treatment should be administered no earlier than 24 hours after the puncture to reduce the need for repeat treatment (3, 14).

Indication

Debilitating, classic, posture-dependent headache after spinal anesthesia, where other differential diagnoses have been considered and excluded. Investigation: Blood pressure, temperature, hemoglobin, white blood cell count, and CRP.

Contraindication

Usual contraindications for spinal anesthesia: Coagulation disorder, anticoagulant treatment, sepsis, infection at the puncture site, patient refusal. In the case of bloodborne infection in the patient, an individual assessment must be made.

Method

Under sterile conditions, the epidural space is located using the usual epidural needle and technique, preferably an interspace caudal to the previous puncture. An assistant (usually a nurse) then performs sterile venipuncture and aspirates at least 20 ml of autologous blood from the patient. The blood-filled syringe is immediately handed to the anesthesiologist for slow injection of the blood (up to 20 ml) into the epidural space. The injection should be stopped if the patient reports back pain. Apply a dressing to the puncture site. Bed rest is recommended for 1-2 hours, followed by careful mobilization.

Freedom from headache is achieved in >70% of PDPH patients treated with a blood patch (2, 3). If the headache recurs with typical symptoms, blood patch treatment may need to be repeated (4, 5).

Since the diagnosis of PDPH is primarily clinical, differential diagnoses must be considered on broad indications. In cases of atypical, persistent, or recurrent symptoms, changes in the type of headache, and/or the development of other neurological symptoms, further investigation with, for example, CT/MRI, must be carried out (2, 6, 8).

Risks/Complications

There is a risk of further dural puncture during the localization of the epidural space. Mild back pain may occur for up to 5 days (3). Infection in the spinal canal. If the blood is accidentally injected subdurally/intradural, it can cause serious complications such as arachnoiditis, cauda equina syndrome, and permanent nerve damage (3, 15, 16).

After PDPH and/or a blood patch, the patient must be closely monitored and not discharged from the hospital if severe headache persists. Detailed oral and written information about the complication and its risks must be provided. Clear instructions on where the patient should go in case of recurrent symptoms. The complication should be documented in the medical record.

During 2016, a European observational study, EPiMAP, was initiated. This study will hopefully provide us with more knowledge about blood patch as a treatment for PDPH.