الفهرس 
Anatomy of the vertebral columnOnly 14 pages are availabe for public view
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Abstract
Spinal (intrathecal) anaesthesia is generally regarded as one of the most reliable of regional block methods: the needle insertion technique is relatively straightforward, with cerebrospinal fluid (CSF) providing both a clear indication of successful needle placement and a medium through which local anaesthetic solution usually spreads readily. However, the possibility of failure has long been recognized.
Failure of a spinal anaesthetic is an event of significant concern for both patient and anaesthetist even when it is immediately apparent, but it can have serious consequences (clinical and medico-legal) if the problem only becomes evident once surgery has started.
If there is any doubt about the nature or duration of the proposed surgery, a method other than a standard spinal anaesthetic should be used.
Literally, the word failure implies that a spinal anaesthetic was attempted, but that no block resulted; this happens, but perhaps a commoner outcome is that a block results, but is inadequate for the proposed surgery.
Such inadequacy may relate to three components of the block: the extent, quality, or duration of local anaesthetic action, often with more than one of these being inadequate. This review has considered all three eventualities within the definition of ‘failure’.
In general terms, block failure is usually ascribed to one of three aspects: clinical technique, inexperience (of the unsupervised trainee especially), and failure to appreciate the need for a meticulous approach.
However, such broad categories reveal little about the many detailed ways in which an intrathecal injection can go astray within each of the five phases of an individual spinal anaesthetic, these being, in sequence, lumbar puncture, solution injection, spreading of drug through CSF, drug action on the spinal nerve roots and cord, and subsequent patient management.
All of the problems involved are well described in the literature.
The trainee anaesthetist should avoid over-selling the technique, especially in the early days of unsupervised practice. Promising that all will be achieved by one injection leaves no room for manoeuvre, but offering one injection to reduce pain and a second to ensure unconsciousness does.
If a spinal anaesthetic does fail in some way, the management options are limited; so, the first rule is to expend every effort in prevention.
The precise management of the failed block will depend on the nature of the inadequacy and the time at which it becomes apparent. Thus, some monitoring of the onset of the block and correct interpretation of the observations are both vital