Spinal and Epidural Placement

Neuraxial Anesthesia 2/ POA EXAM 4

Four sequential clinical phases of spinal placement

Preparation, Access, Placement, and Delivery

Five core steps during the Preparation phase for Spinal and Epidural Placement

Monitors (NIBP and pulse ox), Position patient, PPE (mask/cap on, jewelry removed), cleanly open the kit and don sterile gloves/drapes, and identify/mark landmarks and clean the skin

Three step sequence to safely navigate from the skin to the interspinous ligament during the Access phase

inject 1% Lidocaine to create a skin wheal, advance the introducer needle into the same opening until seated in the interspinous ligament, and hold the introducer steady with the non-dominant hand

Four steps executed during the Placement phase to safely enter the subarachnoid space

advance the spinal needle through the introducer using the dominant hand, feel for a "pop" as it pierces the ligamentum flavum and dura mater, remove the stylet only, and verify a steady flow of 2-3 drops of CSF

Five steps that comprise the Delivery phase of a spinal block

stabilize the needle hub with the non-dominant hand while attaching the syringe with the dominant hand, barbotage (aspirate a small amount of CSF) to verify placement, inject medications, re-aspirate and re-inject a small amount of CSF to confirm stability, and remove the needles and syringe together as a unit in one motion

Immediate action required at the very end of the Delivery phase to finalize the block

place the patient in the position needed to allow spinal medications to migrate to the appropriate height

Primary medication and concentration used to create a skin wheal at the correct interspace

1% Lidocaine

Anatomical structure where the introducer needle must be firmly seated before introducing the spinal needle

interspinous ligament

Respective roles of the dominant and non-dominant hands during spinal needle advancement through the introducer

non-dominant hand holds the introducer steady; dominant hand grabs the spinal needle and carefully advances it

Anatomic layers traversed when the clinician feels a characteristic "pop" during spinal needle advancement

ligamentum flavum and dura mater

Immediate procedural action to take after feeling the "pop" indicating entry through the dura mater

remove the stylet ONLY (leave the spinal needle in place)

Benchmark to confirm successful entry into the subarachnoid space

steady flow of CSF (2-3 drops)

Hand placements when attaching the medication syringe to the spinal needle

non-dominant hand stabilizes the hub of the spinal needle; dominant hand attaches the syringe

Procedural safety action performed immediately after completing the medication injection but before needle removal

re-aspirate and re-inject a small amount of CSF to ensure the needle remained in the correct location

Nine anatomical layers traversed in sequence when using the midline approach for a spinal block

Skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater, and subarachnoid space

Seven anatomical layers traversed in sequence when using the paramedian approach for a spinal block

Skin, subcutaneous tissue, ligamentum flavum, epidural space, dura mater, arachnoid mater, and subarachnoid space

Two distinct spinal ligaments passed during a midline approach that are completely bypassed in a paramedian approach

Supraspinous ligament and interspinous ligament

First dense, resistance-yielding ligament encountered during a paramedian spinal insertion after passing through the skin and subcutaneous tissue

Ligamentum flavum

Specific anatomical space crossed immediately after traversing the ligamentum flavum but before piercing the dura mater

Epidural space

Orientation of the epidural needle (Tuohy) when first advancing into the skin

Bevel up

Target anatomical structure for initial firm seating of the Tuohy needle

Interspinous ligament

Typical volume of saline or air used in the Loss of Resistance (LOR) syringe

3-4 mL

Physical sensation confirming the Tuohy needle has passed through the ligamentum flavum into the epidural space

Sudden "loss of resistance" to pressure on the syringe plunger

Standard distance for threading the epidural catheter beyond the point of Loss of Resistance

3-5 cm

Procedural step performed after catheter placement to check for intravascular or subarachnoid placement

Negative aspiration of heme or CSF through the catheter using a 3 cc syringe

Medication and dose used for the epidural "test dose"

3 mL of 1.5% Lidocaine with 1:200,000 epinephrine

Final procedural step taken after confirming a negative test dose

Secure the catheter and then position the patient to the appropriate height for the procedure

Four sequential clinical phases used to divide the workflow of epidural placement

Preparation, Access & Setup phase, Identification & Threading, and Securing & Safety phase

Four precise steps required to transition from the skin to the loss of resistance setup during the Access & Setup phase

Inject 1% Lidocaine for a skin wheal, advance the Tuohy needle bevel up until seated in the interspinous ligament (~2-3 mm), stabilize the needle with the non-dominant hand, and attach the LOR syringe containing 3-4 mL of saline or air using the dominant hand

Hand mechanics and visual cues that define the Identification & Threading phase of an epidural

Non-dominant hand slowly advances the needle (1 mm at a time) while the dominant thumb maintains constant/intermittent pressure on the plunger until a sudden "loss of resistance" occurs, then the needle is stabilized with the non-dominant hand while the dominant hand slowly advances the catheter

Continuous motion required when removing the Tuohy needle over the newly placed catheter

Maintain a constant forward threading motion on the catheter while slowly removing the epidural needle from the skin

Six layers traversed in sequence when using the midline approach for an epidural block

Skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, and epidural space

Four anatomical layers traversed in sequence when using the paramedian approach for an epidural block

Skin, subcutaneous tissue, ligamentum flavum, and epidural space

First dense, resistance-yielding ligament encountered during a paramedian epidural insertion after passing through the skin and subcutaneous tissue

Ligamentum flavum

Final anatomical endpoint layer where the needle terminates for a successful epidural placement

Epidural space

Landmark that must be reached with the Tuohy needle before performing a dural puncture epidural (DPE)

Loss of resistance (LOR) is noted

Specific size of the spinal needle used to intentionally puncture the dura during a DPE technique

25g

Visual confirmation required before removing the spinal needle during a DPE procedure

CSF is noted

Absolute restriction regarding the spinal needle during a DPE

No medications are given through the spinal needle

Ultimate clinical mechanism and therapeutic goals of performing a dural puncture epidural technique

Local anesthetic (LA) and opioids given through the epidural will migrate through the hole in the dura to enhance epidural block density, improve block bilaterality, and enhance sacral analgesia

Core neuraxial technique that simultaneously offers the therapeutic benefits of both spinal and epidural anesthesia

Combined Spinal Epidural (CSE)

Dosing strategy used for intrathecal medications administered via the spinal needle during a CSE

Low dose spinal medications

Primary clinical goal of a Combined Spinal Epidural (CSE) regarding onset and duration

Immediate sensory and motor block with the spinal and ability to supplement/continue anesthesia or analgesia through the epidural catheter

Two environments where a CSE is most frequently utilized

OB practice or long surgical procedures (such as orthopedic)

Two distinct clinical circumstances under which continuous spinal anesthesia may be performed

Electively or after an inadvertent entrance into the subarachnoid space

Specific distance an epidural catheter should be threaded into the subarachnoid space for continuous spinal anesthesia

2-3 cm

Anatomical direction the catheter must be directed when threading into the subarachnoid space during continuous spinal anesthesia

Cephalad

Causes that can lead to a failed neuraxial block

Incorrectly identified subarachnoid space, failure to inject all/part of LA into the space, LA maldistribution, LA solution not placed in the epidural space, inadequate spread of LA, or false loss of resistance (LOR)

Which type of neuraxial block has a higher rate of failure?

More caudad spaces have higher rates of failure

Clinical assumption required if repeating a failed spinal block

Assume the entire first dose reached the subarachnoid space.

Primary causes of neurological complications following spinal anesthesia

Trauma from the needle or catheter, hematoma, or abscess formation

Transient Neurologic Symptoms outcome

Usually transient and resolves postoperatively

Action that increases the frequency and intensity of a permanent paresthesia injury

Injecting local anesthetic (LA) while active paresthesia is noted --> LA pooling

Dose and space risk factor that can result in permanent neurological injury

Large doses of local anesthetic (LA) in restricted areas (such as the subarachnoid space)

Local anesthetic and baricity most frequently associated with Transient Neurologic Symptoms (TNS)

Hyperbaric lidocaine

Surgical patient position most commonly linked to the development of TNS

Lithotomy position

Critical signs and symptoms of TNS

Back pain with radiation to the legs WITHOUT sensory or motor deficits

Onset timing and typical clinical resolution window for TNS symptoms

Occurs after the block has resolved; self-limiting and usually resolves within 3 days (72 hours)

Causes of hypotension following a sympathetic nervous system block

1) Decreased venous return to the heart and decreased cardiac output (CO), or 2) decreased systemic vascular resistance (SVR)

the severity and degree of neuraxial-induced hypotension varies based on ________

Sensory level of the spinal anesthesia and the fluid status of the patient

Why neuraxial hypotension frequently triggers nausea and vomiting (N/V)

Hypoperfusion to the brainstem

Prophylactic strategies used to prevent hypotension during neuraxial anesthesia

Preload or co-load fluids, avoid high levels of block, position the patient slowly, exercise caution with preoperative sedation, and use left uterine displacement (LUD) in OB patients

Treatments for acute neuraxial hypotension

IV fluids, vasopressors (phenylephrine, ephedrine), and elevating the legs or adjusting the HOB to a slight Trendelenburg position

Relationship between block height and the risk of developing bradycardia

Risk of bradycardia increases with increasing sensory block levels

Spinal levels and reflex responsible for neuraxial bradycardia

T1–T4 cardioaccelerator blockade and the Bezold-Jarisch reflex

First-line pharmacological agents used to treat neuraxial bradycardia

Atropine or glycopyrrolate

Three conditions where neuraxial sympatholysis severely worsens low venous return

Ascites, pregnancy, and vena cava obstruction.

Defining feature of a Post-Dural Puncture Headache (PDPH)

Postural nature: intensifies when sitting or standing, resolves when lying flat.

Symptom onset for PDPH

12–48 hours after puncture.

Conservative treatment & dose for PDPH

500 mg IV Caffeine.

Postoperative positioning immediately following an epidural blood patch

Supine for 2 hours.

Mandatory waiting period before repeating a failed epidural blood patch

24 hours.

Parasympathetic block to relieve PDPH (uncommon)

Sphenopalatine ganglion

Cause of apnea and LOC during high spinal anesthesia

Ischemic paralysis of medullary ventilatory centers (2/2 to profound hypotension and decreased cerebral blood flow)

Indicators a high spinal block is ascending toward thoracic and cervical levels

Upper extremity weakness and dysphonia.

Patient positioning for acute treatment of high spinal anesthesia

Head-down position to facilitate venous return.

Clinical concern when a patient experiences immediate nausea and vomiting after a neuraxial block

Systemic hypotension causing cerebral ischemia.

Autonomic imbalance responsible for neuraxial nausea and vomiting

Parasympathetic (PNS) predominance caused by selective blockade of sympathetic (SNS) GI tract innervation.

Primary clinical focus when evaluating and treating a post-procedural backache

Monitoring symptoms to ensure they are not worsening or causing neurological deficits.

Incidence range for urinary retention following neuraxial anesthesia

5-70%

Nerve roots blocked resulting in neuraxial-induced urinary retention

S2-4

Bladder changes responsible for neuraxial urinary retention

Decreased urinary bladder tone and inhibition of the voiding reflex

Preventative strategy to decrease the risk of post-block urinary retention

Avoid excessive IVF (intravenous fluids)

Why is Local Anesthetic Systemic Toxicity (LAST) more common with epidural than spinal placement?

Epidurals require a significantly higher volume of local anesthetic.

Three primary causes of LAST

Intravascular injection, overdosing, or decreased metabolism of local anesthetics.

What dictates the presentation of signs and symptoms in LAST?

Plasma concentration of the local anesthetic.

Progression of CNS symptoms in LAST from early signs to severe toxicity

Lightheadedness, dizziness, visual/auditory disturbances, circumoral/tongue numbness, metallic taste, twitching/tremors, and convulsions.

Progression of cardiovascular symptoms in LAST from early signs to severe toxicity

Hypotension (HoTN), ECG changes, ventricular fibrillation, and cardiac arrest.

Pathophysiological for the cardiovascular effects of LAST

Direct effects of local anesthetics on cardiac muscles and peripheral vascular resistance.

(5) prophylactic strategies used to prevent LAST

Aspirate prior to injection, utilize a "test dose," inject in increments (~5 mL), know maximum local anesthetic doses, and closely monitor patient signs/symptoms.

Three main elements of acute treatment for LAST

ABC management, treating seizures if present, and administering Intralipids 20%

Three initial team and resource coordination steps when managing LAST

Call for help, get the LAST rescue kit, and consider mobilizing the cardiopulmonary bypass team.

LAST Dose and administration of 20% lipid emulsion for a patient over 70 kg

Bolus ~100 mL over 2–3 minutes & Infuse ~250 mL over 15–20 minutes.

LAST Weight-based bolus dose and administration of 20% lipid emulsion for a patient under 70 kg

Bolus ~1.5 mL/kg over 2–3 minutes. & Infuse ~0.25 mL/kg/min. (consider pump in <40 kg)

Interventions if LAST patient remains hemodynamically unstable despite initial lipid therapy

Repeat the lipid bolus and double the infusion rate.

First-line preferred medication for treating LAST-induced seizures

Benzodiazepines.

Alternative dosing rule for seizures if propofol is the only available agent

Use low doses in 20 mg increments.

Dosing modification required for epinephrine during LAST cardiovascular resuscitation

Use smaller than normal doses, starting with <1 mcg/kg.

Four classes of cardiovascular medications or specific drugs to strictly AVOID during LAST resuscitation

Local anesthetics, beta-blockers, calcium channel blockers, and vasopressin.

Minimum duration to continue a lipid emulsion infusion once hemodynamic stability is achieved

<15 minutes.