Spinal AnaesthesiaSpinal Anaesthesia

• Indications ( when to use )Indications ( when to use )

• Contraindications ( when not to use )Contraindications ( when not to use )

• Desired Effects Desired Effects

• Undesired EffectsUndesired Effects

• MonitoringMonitoring

• Local Anaesthetic Drugs Used and DosagesLocal Anaesthetic Drugs Used and Dosages

• Additive drugs usedAdditive drugs used

• TipsTips

Spinal Anaesthesia : Spinal Anaesthesia : Indications ( when to use )Indications ( when to use )

• Suitable for surgeries below T-8 ( mid abdomen )Suitable for surgeries below T-8 ( mid abdomen )

• Examples include : Examples include :

• Cesarian section, hysterectomy, hernia repair, perineal surgeryCesarian section, hysterectomy, hernia repair, perineal surgeryBladder and lower urinary tract surgery, lower limb Bladder and lower urinary tract surgery, lower limb orthopaedic surgery and others ……orthopaedic surgery and others ……

• It is considered the method of choice for Cesarian sections as it It is considered the method of choice for Cesarian sections as it eliminates the need to manage high risk airways, and for TURP eliminates the need to manage high risk airways, and for TURP as it allows early recognition of symptoms of TURP syndromeas it allows early recognition of symptoms of TURP syndrome

Spinal Anaesthesia : Spinal Anaesthesia : Indications ( when to use )Indications ( when to use )

• ConsiderationsConsiderations

• Duration of Surgery – Duration of Surgery – even long acting agents regress after even long acting agents regress after 2.5 – 3 hours despite epinephrine. Longest acting probably 2.5 – 3 hours despite epinephrine. Longest acting probably isobaric tetracaine / bupivicaine plus epi/fentanylisobaric tetracaine / bupivicaine plus epi/fentanyl

• Site of Surgery – Site of Surgery – Some lower abdominal surgeries require Some lower abdominal surgeries require higher blocks due to traction on pain sensitive visceral higher blocks due to traction on pain sensitive visceral structures such as testicles and ovaries structures such as testicles and ovaries

• Hemodynamic Stability –Hemodynamic Stability – spinals will cause a reduced spinals will cause a reduced venous return and blood pressure due to vasomotor venous return and blood pressure due to vasomotor paralysis paralysis ( venodilatation )( venodilatation )

Spinal Anaesthesia : Spinal Anaesthesia : Contra-iIndications ( when not to use ) Contra-iIndications ( when not to use )

• Coagulopathic Patients – Coagulopathic Patients – spinal needle may result in spinal needle may result in hematoma formation in pt on blood thinners, with low platelets hematoma formation in pt on blood thinners, with low platelets ( generally < 50 as long as plts functional eg-not uremic ) or other ( generally < 50 as long as plts functional eg-not uremic ) or other coagulopathies.coagulopathies.

– Wait atleastWait atleast : :

– 12 hours since last dose of heparin12 hours since last dose of heparin– 24 hours since last dose of low molecular weight heparin24 hours since last dose of low molecular weight heparin– 3-4 days since last dose of warfarin ( check INR )3-4 days since last dose of warfarin ( check INR )– 3-4 days since last dose of F10A inhibitors ( as long as renal function 3-4 days since last dose of F10A inhibitors ( as long as renal function

OK )OK )– 7-10 days since last dose of platelet inhibitor ( cycloprigel, ticlidopine )7-10 days since last dose of platelet inhibitor ( cycloprigel, ticlidopine )– ASA or Non steroidal anti-inflammatories OK !!!ASA or Non steroidal anti-inflammatories OK !!!

Spinal Anaesthesia : Spinal Anaesthesia : Contra-indications ( when not to use )Contra-indications ( when not to use )

• Hypotensive or unstable patients Hypotensive or unstable patients – – spinals reduce blood spinals reduce blood pressurepressure

• Septic patients Septic patients

• Skin infection in path of needle Skin infection in path of needle • Patients with fixed cardiac obstruction – Patients with fixed cardiac obstruction – Severe Aortic Stenosis Severe Aortic Stenosis

or Pulmonary Hypertension – may not be able to compensate for or Pulmonary Hypertension – may not be able to compensate for venodilationvenodilation

• Patients with seriously impaired ventricular function – Patients with seriously impaired ventricular function – these patients requirethese patients require adequate ventricular filling pressures to maintain adequate ventricular filling pressures to maintain cardiac output and spinals will decrease venous return cardiac output and spinals will decrease venous return

• Patients with Significant CNS Pathology – Patients with Significant CNS Pathology – elevated ICP, arterio- elevated ICP, arterio- venous malformations, spina bifida, ? previous spinal surgery and venous malformations, spina bifida, ? previous spinal surgery and congenital problemscongenital problems

Spinal Anaesthesia :Spinal Anaesthesia : Desired Effects Desired Effects

• Spinals will result in a somatic and autonomic paralysisSpinals will result in a somatic and autonomic paralysis

• Typically sensory and motor function is abolished although Typically sensory and motor function is abolished although one may lag behind the otherone may lag behind the other

• Dull sensation to pressure may persist but not painfulDull sensation to pressure may persist but not painful

• Generally, respiratory function is well maintained unless Generally, respiratory function is well maintained unless block is very high – loss of sensation of chest wall block is very high – loss of sensation of chest wall movement movement

( breathing ) may be alarming to patients( breathing ) may be alarming to patients

• Vasodilatation beneficial ( as with epidural ) for vascular Vasodilatation beneficial ( as with epidural ) for vascular proceduresprocedures

• Although insensate, patients may require some anxiolysisAlthough insensate, patients may require some anxiolysis

Spinal Anaesthesia : Spinal Anaesthesia : Undesired EffectsUndesired Effects

• Hypotension – Hypotension – leading to cardiac arrestleading to cardiac arrest

• InfectionInfection• Spinal HematomaSpinal Hematoma• Bradycardia - Bradycardia - ( cardiac sympathetic innervation @ T4 )( cardiac sympathetic innervation @ T4 )

• Respiratory Distress Respiratory Distress –– loss of abdominal and intercostal function in loss of abdominal and intercostal function in susceptible individualssusceptible individuals

• Inadequate Anaesthesia – Inadequate Anaesthesia – due to anatomical or post operative due to anatomical or post operative changeschanges

• Worsening of CNS pathologyWorsening of CNS pathology – – bleed from AVM, aneurysm, brainstem bleed from AVM, aneurysm, brainstem herniationherniation

• Post Dural Puncture Headache – Post Dural Puncture Headache – postural – rare over the age of 60 postural – rare over the age of 60 and minimized with the use of small ( 25-27g ) pencil point needles and minimized with the use of small ( 25-27g ) pencil point needles ( Whitacre )( Whitacre )

• Nerve Toxicity – Nerve Toxicity – with hyperbaric lidocine ( transient )with hyperbaric lidocine ( transient ) , , rare with othersrare with others– Use preservative free solutions onlyUse preservative free solutions only

Spinal Anaesthesia :Spinal Anaesthesia : MonitoringMonitoring

• Standard monitoring appliesStandard monitoring applies– Most catastrophic events will occur at 20 – 30 min but can Most catastrophic events will occur at 20 – 30 min but can

occur up to 1 hour after the block – be vigilant !!occur up to 1 hour after the block – be vigilant !!

• BP, SaO2, ECGBP, SaO2, ECG

• Best way to determine dermatomal spread is light scratch Best way to determine dermatomal spread is light scratch or coldor cold

• T4 T4 nipples nipples

• T6T6 costal margincostal margin

• T10T10 umbilicus umbilicus

Spinal Anaesthesia : Spinal Anaesthesia : Drugs and DosagesDrugs and Dosages

• Hyperbaric –Hyperbaric – heavier than CSF and migrates in CSF heavier than CSF and migrates in CSF gravitationallygravitationally

• Typically pools in thoracic kyphosis resulting in higher blockTypically pools in thoracic kyphosis resulting in higher block

• T4-T6 usual – useful for mid and lower abdominopelvic T4-T6 usual – useful for mid and lower abdominopelvic proceduresprocedures

• Bupivicaine typically 12 – 15 mg less in pregnancy, obesityBupivicaine typically 12 – 15 mg less in pregnancy, obesity

• Tetracaine diluted in D10W – 15-20 mg Tetracaine diluted in D10W – 15-20 mg

• Perineal ( saddle ) block if left sitting 1min post injectionPerineal ( saddle ) block if left sitting 1min post injection

Spinal Anaesthesia : Spinal Anaesthesia : Drugs and DosagesDrugs and Dosages

• Isobaric -Isobaric -Less cephalad spread – medication diffuses nearer Less cephalad spread – medication diffuses nearer injection site injection site

• Useful for lower extremity proceduresUseful for lower extremity procedures

• Bupivicaine 12.5 – 20 mg lasts 3 – 3.5hrsBupivicaine 12.5 – 20 mg lasts 3 – 3.5hrs

• Tetracaine diluted with saline 15 – 20 mg lasts 3 – 3.5 hrsTetracaine diluted with saline 15 – 20 mg lasts 3 – 3.5 hrs

• Lidocaine 40 – 60 mg lasts 1 – 1.5 hrsLidocaine 40 – 60 mg lasts 1 – 1.5 hrs

• 2-Chloroprocaine 40 – 60 mg lasts 45 min – 1 hr2-Chloroprocaine 40 – 60 mg lasts 45 min – 1 hr

Spinal Anaesthesia :Spinal Anaesthesia :Additive drugs usedAdditive drugs used

• All drugs must be preservative freeAll drugs must be preservative free

• Epinephrine 5 mcg/ml prolong lidocaine block ; less with Epinephrine 5 mcg/ml prolong lidocaine block ; less with bupivicainebupivicaine

• Fentanyl 20 mcg potentiates block and may allow for less Fentanyl 20 mcg potentiates block and may allow for less local anaestheticlocal anaesthetic

• Morphine 200 – 300 mcg provides long lasting analgesia but Morphine 200 – 300 mcg provides long lasting analgesia but beware delayed respiratory depression ( 8 hrs ) and beware delayed respiratory depression ( 8 hrs ) and troublesome side effects such as pruritus and nauseatroublesome side effects such as pruritus and nausea

Spinal Anaesthesia :Spinal Anaesthesia :TipsTips

• Sitting positon preferred – if lateral, ensure good fetal Sitting positon preferred – if lateral, ensure good fetal positionposition

• Only use 22g on patients >60 or if urgent, or difficultOnly use 22g on patients >60 or if urgent, or difficult– Otherwise 25 – 27 g through introducer to minimize Otherwise 25 – 27 g through introducer to minimize

PDPH PDPH – The smaller the betterThe smaller the better– Whitacre or Sprotte needles if possibleWhitacre or Sprotte needles if possible

• Sedation helpfulSedation helpful

• Small dose ketamine useful for positioning # hip in lateral Small dose ketamine useful for positioning # hip in lateral positionposition

• Paramedian approach usefulParamedian approach useful