A. Borgeat Orthopedic University Clinic of Zurich/Balgrist Switzerland

Failed spinal anesthesia: mechanisms, management and prevention

Why did my spinal fail?

76

14 10

RA RA+GA GA

Survey in UK trauma centers

Sandby-Thomas et al Anaesthesia 2008;63:250,

%

SPA

96 %

n = 100

Success: no inhalation anesthetic agents required for surgery

Failure rate: 17 % associated with :

• lack of free flow of CSF

• use of tetracaine without epinephrine

• an increased administration of IV supplementation

Anesth Analg 1985; 64:705,

n = 329

Success: no GA or supplementary analgesics required

Failure rate: 3 % associated with :

• all were ASA III

• tetracaine (8%)vs lidocaine (2%)

• tetracaine with epinephrine (13%) than without (5%)

→ no other correlation was found

Anesth Analg 1987; 66:363,

n = 200 Failure: If the surgical procedure could not be performed without the addition of GA

Failure rate: 4 %

• 25% due to errors in technique

• 75% due to errors in judgement

Anesth Analg 1988; 67:843,

Failure rate in relation to demographic variables

Variables

Total number of

spinal anesthetics

Successful

spinal anesthetics

Failed spinal

anesthetics

Failure

rate (%)

Sex male female Ethnic group white black hispanic other Age (yrs) 16 - 20** 20 - 40 40 - 60 60 - 80

146 54

60 94 38 8 2 59 55 84

144 48

59 91 34 8

2 55 53 82

2 6

1 3 4 0

0 4 2 2

1.4

11.1*

1.7 3.2

10.5 0

0 6.8 3.6 2.4

* Difference highly significant (p< 0.05) ** Not included in statistically analysis, because number was too small

Munhall et al Anesth Analg 1988; 67:843,

Factors affecting success of failure of spinal anesthesia

Technical factors 1. Identification of subarachnoid space; related to training; ability to

utilize different approaches 2. Documentation of free flow of CSF pre- and postinjection 3. Proper placement of catheter for continuous spinal technique

Pharmacological factors (judgement error) 1. Selection of appropriate local anesthetic and addition of

vasoconstrictor; depending on duration of surgery 2. Selection of appropriate dosage and baricity 3. Selection of appropriate position and interspace; depending on

site of surgery 4. Selection of appropriate technique; single injection versus

continuous catheter technique

Munhall et al Anesth Analg 1988; 67:843,

All types of surgery. No CSF backflow was an exclusion criteria

Failure rate 3,2 %

total failure 41 % (no sensory block)

partial failure 59 % (insufficient block)

independent risk factors - younger age - number of attempts >3 (CI 95 % 1.2 – 6.8) - no adjuvant with LA (CI 95 % 1.2 – 4.5)

age >70 was a factor decreasing the risk of failure (CI 95 % 0.2 – 0.9)

Fuzier et al. RAPM 2011;36:322,

Spinal n = 3227 Epidural n = 1286 94 % success 76 %

Factors associated with failure: Pre-operative failure Intraoperative failure - body mass index - inadequacy of pre-operative block - no previous C section - duration of surgery - C section for acute fetal distress - C section failure elective 0.8% emergency 4.9% - NB: adding an opioid was associated with less failure

Kinsella S.M. Anaesthesia 2008;63:822,

• Prospective cohort study involving 800 parturients (0.5 heavy bupivacaine + morphine 100 ug / Whiteacre 27 G)

• Goal : block at T5 Failure rate 0.5 %

75 % inadequate block

(block at T6)

25 % no block

All failures - sitting position - free flow of CSF Sng et al

Int J Obstet Anesth 2009;18:237,

Br J Anaesth 2009;102:739 Failures associated with spinal bupivacaine

administration

Two conditions are, therefore, absolutely necessary to produce spinal anesthesia: puncture of the dura mater and subarachnoidal injection of an anesthetic agent

Gaston Labat 1922

Failed Spinal Anesthetic

The drug works, but the dosage has not been chosen correctly

Impossibility to reach the subarachnoidal space

The drug has been injected at the right location, but the block does not work as expected

Circulation of the cerebrospinal fluid

Cerebrospinal fluid Functions • Protection against trauma due to sudden movement • Maintain a uniform pressure upon the brain and cord • Reduced the effective weight of the brain

Characteristics • Produced from blood in the choroid plexuses (90 %) in the fourth

ventricle and is absorbed back into the blood by the arachnoid granulations

• Volume is + 150ml, but a nearly threefold variability in healthy adults has been observed

Spinal failure despite correct dosing and injection technique

• Maldistribution

may be associated with variation concerning spreading of subarachnoidal block

Blomberg R.G. Anesth Analg 1995; 80:875,

Tarlov Cyst

• Fluid-filled nerve root valved or nonvalved cysts found most commonly at the sacral level of the spine

• Asymptomatic TC are present in 5-9 %. Female are more frequently affected

• Treatment is drainage of CSF or surgery

Tarlov Cyst as a cause of spinal failure

Spinal failure despite correct dosing and injection technique

• Maldistribution • Variability in the anatomy of the lumbar

subarachnoid space

Anesthesiology 1998;89: 24,

10 healthy volunteers received a spinal with 50 mg lidocaine in 7.5 dextrose Lumbosacral CSF volumes were calculated using MRI

Positive correlation between CSF volume and sensory block extension and duration of surgical anesthesia, but no correlation with onset of sensory/ motor block and duration of motor blockade

43 81 ml

lumbosacral CSF

n = 2600 failure rate 2,7 %

B U P I V A CAI N E

CSF

adequate block

inadequate block inadequate CSF

concentration

maldistribution 60 %

40 %

73

range 3,36 to 1020 ug.ml-1

Steiner et al. Br J Anaesth 2009;102:839

ug.ml -1

- No association between CSF bupivacaine and spinal block level

- Similar variability between men and women

Ruppen W. et al Br J Anaest 2009;102:832,

Magnetic resonance images of the lumbosacral spine a) Patient with usual thecal dimensions b) Patient with large thecal dimensions

Compare the intrathecal dimensions of the patient in b) to the patient in a)

Spiegel JE and Hess P J Anesth 2007;21:399,

Widening/balloning of the lumbosacral dural sac in 63 – 92 % of patients with Marfan‘s syndrome

Br J Anaesth 2005;94:500,

Spinal failure despite correct dosing and injection technique

• Maldistribution • Variability in the anatomy of the lumbar

subarachnoid space • Inadvertent subdural or epidural injection

Br J Anaesth 2009;102:739

Failed spinal due to altered bupivacaine

- Inadequate sensory block - Prolonged onset of block - Insufficient duration of block - No block

Background 8 spinal failures in 1 week period

276

289 control suspect bupivacaine

bupivacaine was exposed more than 9h to freezing temperatures

chemical alteration (?) Blasiole et al

ASA 2009

mass/charge ratio

Mass spectroscopy

• 16 % failed continuous spinal with hyperbaric lidocaine • Free flow of CSF • CSF lidocaine concentration 420 – 880 ug/ml • Injection of bupivacaine produced anesthesia • Plain lidocaine from the same manufacturing batch

produced anesthesia

J Clin Anesth 1990;2: Sept/Oct

BMC Anesthesiology 2004;4:1,

The world of Na+ channels

• Voltage-gate Na+ channels are crucial for electrogenesis and nerve impulse conduction

• Voltage-gate Na+ channels are important targets for analgesics like LA or carbamazepine

• Recent studies have identified different sodium isoforms

Voltage-gate Na+ channel

Nav1.5 Nav1.6 Nav1.7 Nav1.8 Nav1.9

Pain Inflammation

Pain Inflammation

Pain Inflammation

Ranvier nodes

Cardiac muscle

Nav1.7

• Nav1.7 plays a crucial role in the human ability to perceive pain

• Loss-of-function mutations in the Nav1.7 gene underlie congenital indifference to pain

• No organic dysfunction except for some cases of anosmia or hyposmia

N395K mutation attenuates the

inhibitory effect of lidocaine

Patrick L. et al J Physiol 2007:581:1019,

Pan et al. Can J Anesth 2002;49:636

Sucess of spinal anesthesia

Right place

Right drug

Right dosage

Conclusions

Lumbar punction

Solution injection

Failure

Failure

Failure

Spreading of drug through CSF

Drug action on the spinal nerve roots and cord