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By Dr.AyshvaryaM.D Post-Graduate
Guide: Dr Sendhil Kumar MohanDr.R.Selvakumar.M.D.D.A.DNB
Moderator: Dr.N.JothiK.A.P.Viswanatham Govt Medical College
TrichirapalliTamilnadu-India
Sub-arachnoid Block Failure
Neuraxial Blockade involving injection of local anaesthetic in the
sub-arachnoid space
Spinal anesthesia can be classified as a failure if the surgical
operation cannot be performed without the addition of general
anesthetic or an alternative regional block
No blockade
Inadequate Block for the surgery
Spinal Anaesthesia
The incidence of failure with spinal
anesthesia varies in different studies,
ranging from 3% to 17%.
In some smaller studies, failure rates
as high as 30% have been reported
More among unsupervised trainees
Incidence of Failure
clinical technique
inexperience
failure to appreciate the
need for a meticulous approach
Reasons for failure
Lumbar Puncture
Drug Solution Injection
Spreading Of Drug Through
CSF
Drug Action On The Spinal
Nerve Roots And
Cord
Subsequent Patient
Management
Phases in administering a
Spinal anaesthesia
Aim is to optimize the pt’s position & prevent any movement
anxiolytic premedication
local anaesthetic infiltration at the puncture site
Patient Positionin
g
Abolishing the natural lumbar lordosis by flexing maximally the whole spine (including the neck), the hips, and knees increases the space between the lumbar laminae and spines
Sitting or Lateral
Poor Patient Positioning
Lateral Position
Sitting position confers the advantage of
making the midline easier to identify, particularly in obese patients
increases hydrostatic pressure in the CSF, which may make spinal needle placement and fluid aspiration easier
Approach
Midline approach
Can be angulated cephalad when
resistance is felt
Lateral/Paramedian approach- when the
ligaments are calcified
Mental picture of the spinal anatomy
& Appreciation of loss of resistance
Needle Insertion
Size 18 to 25G do not affect the
success rate
Thinner needles, greater
tendency to deviate, slower
appearance of CSF in the hub,
more chances of failure
NEEDLE FACTORS
Opening is proximal to the tip to prevent PDPH
Small displacement can cause drug deposition in epi/subdural
space
Opening is longer than in Quincke’s, resulting in dura acting as a
flap valve across the opening
Pencil point needles
Dry tapThe needle & stylet should be checked for any block
Pseudolumbar puncture
Needle should not be inserted without the stylet
Failed Lumbar
Puncture
A fully effective dose should be both chosen and actually deposited in the CSF
DRUG SOLUTION INJECTION
ERRORS
Determines the quality & duration of the block
Factors influencing intrathecal drug spread & the LA drug
With low-dose, selective or U/L spinal anesthesia, the proper technique more important than with higher doses.
whole of the dose must be delivered into the CSF, including the dead space of the needle.
DOSE SELECTION
Connection between syringe and needle provides a ready opportunity for leakage of solution
The syringe containing the injectate must be inserted very firmly into the hub of the needle to prevent such leaks
LOSS OF INJECTATE
Anterior or posterior displacement of the needle tip, while
attaching the syringe to the needle
aspiration to confirm free flow of CSF
force of the injection of the syringe contents
Misplaced injection
Subdural injection of drugHigh
sensory block,
sparing of sympathetic & motor
Failure of block
• Kyphosis, or scoliosis
• Ligaments can form complete
septae within the theca acting
as barriers to the spread
• Spinal stenosis
• Sequelae of previous
intrathecal chemotherapy
• Cysts within the subarachnoid
space- saccular dilatations of
the septum posticum
Anatomical Abnormaliti
es
INADEQUATE INTRATHECAL SPREAD
Lumbar CSF volume variability • dural ectasia in marfan’s, & some
connective tissue disorders
Pre procedural USG can be of help in identification & managament of difficult spinal
Iso & Hypobaric – spread is less predictable
If lumbar puncture is performed at L4-L5 or the lumbo-sacral
interspace, the LA may be ‘trapped’ below the lumbar curve (sitting
posture)-saddle block
SOLUTION DENSITY
Identification errors
Concentration errors
Alkaline pH of CSF altering pKa of LA,
bloody tap
Loss of potency
Chemical incompatibility• Precipitation or
decreasing the concentration of the un-ionized fraction
Local anaesthetic resistance
INEFFECTIVE DRUG ACTION
Anxious patients
Requires good preoperative patient counseling
followed by a supportive approach, with
intraoperative sedation
FAILURE OF SUBSEQUENT MANAGEMENT
Advisable to start testing in the lower segments,
where onset will be fastest, and work upwards.
Proving early on that there is some effect
encourages patient confidence; testing too soon
does the opposite
TESTING THE BLOCK
Problems of inadequacy & duration
can be solved by using either
continuous spinal or
combined spinal–epidural
techniques
Introducing a catheter may be
difficult in subarachnoid space
To Avoid misdirection of LA solution-
not more than 2-3cm in intrathecal
space
Catheter and
combined
techniques
Salvage the
block
Repeat
Spinal Technique
General
Anaesthes
ia
Options in
Managing a
Failed Spinal
Choice for correct option
Time of onset of failure
Technical difficulty
Complete/Partial
Comorbidities
REPEAT SPINAL
Partial block No block
Reduced dose Full dose
It should be performed by an
experienced senior anaesthesiologist.
Preferably in a sitting position, to avoid
high spinal In Partial block, the combination of the 2
doses should not exceed that considered reasonable as a single injection for spinal anesthesia
Advantages• Simple to perform• Avoids the complications
associated with GA
Complications• Excessive cephalic spread,
Exaggerated hypotension• Risk of direct nerve damage• PDPH• Multiple attempts- epidural
haemotoma• If the initial failure-anatomical
reasons, Repeat spinal- same effect
• Local anaesthetic toxicity
REPEAT SPINAL
Aspiration of CSF should be attempted before & after injection of anaesthetic
Sacral dermatomes should be included in evaluation of spinal block
If CSF is aspirated after anaesthetic injection – LA has been delivered into Subarachnoid space
Avoid reinforcing the same restricted distribution
If CSF not aspirated after injection- tincture of time, carefully assess the blockade and repeat full dose only if there is no evidence of block
Recommendations for Anesthetic Administration after a “FAILED SPINAL”
Technique of choice in Failed spinal
UnpreparednessDifficult airwayPresence of comorbid illnessesAspiration risk in emergency surgeries/CSHypotension due to sympathetic blockade due to SAB
Advantages
:
Disadvanta
ges:
GENERAL ANAESTHESIA
Inadequate spread due to vertebral canal
pathology-
R/O any signs & symptoms of Neurological disease
Investigating local anaesthetic effectiveness
When series of failures in a short period of time
Performing skin infiltration with some of the solution
intended for the spinal injection should demonstrate that
it is effective
FOLLOW-UP INITIATIVES
In 1907 Alfred E. Barker wrote that for successful spinal analgesia it
is necessary
‘to enter the lumbar dural sac effectually with the
point of the needle, and to discharge through this, all
the contemplated dose of the drug, directly and freely
into the cerebrospinal fluid, below the termination of
the cord’ (Barker, 1907).
Failure to follow the details of this advice is the commonest cause
of a poor result
Cousins & Bridenbaugh’s Neural Blockade In Clinical Anaesthesia & Pain Medicine
Complications of Regional Anaesthesia, Brendan T. Finucane
Br. J. Anaesth. (2009) 102 (6):739-748.doi: 10.1093/bja/aep096First published
online: May 6, 2009
Pokharel, A. "Study of Failed Spinal Anesthesia Undergoing Caesarean Section and
Its Management." Post-Graduate Medical Journal of NAMS 11.02 (2011).
Analgesia & Anesthesia in Labor and Delivery By D. K. Baheti
Basics of Anesthesia, 6th Ed by Ronald Miller