4.
Pain therapy
In 1979, a commission set up by the International Association for the Study of Pain (IASP) defined pain as “… an unpleasant sensory and emotional experience, linked to actual or potential tissue damage” [1].
Acute pain is caused by stimulation of pain receptors. This stimulation is transient and sets in motion biologically useful protective mechanisms. Ideally, pain can be relieved by treating the cause. Chronic pain is regarded as a pathological response on the part of the body. The relief of acute pain should be viewed as a “human right.” In this context, there are a significant number of patients who will not obtain effective pain relief without access to potent neural blockade techniques.
It arises due to constant stimulation of nociceptive afferents or can develop as neuropathic pain after injury or damage to the peripheral nociceptive system [2, 3, 5, 6].
Chronic pain can often lead to alterations in patients’ living habits, physical abilities, and personality and requires a coordinated interdisciplinary approach. This in turn presupposes a clear diagnosis, based on a full general history and pain history, physical examination, and functional assessment of the patient’s musculature, locomotor apparatus, autonomic nervous system, and neurological and angiological situation.
In addition to medical treatment for pain, nerve blocks have a firmly established place in pain therapy—alongside physical and manual procedures, neurological and neurosurgical methods, physiotherapy, and the psychosocial management of patients. In quantitative terms, regional anesthesia procedures play only a minor part in the management of chronic pain, but qualitatively they can produce very good results when used with the correct indications.
Nerve Blocks in Surgery and Pain Therapy (Table 2.2)
Table 2.2
Important rules to observe when administering regional anesthesia or therapeutic nerve blocks
Before the block |
Patient 1. Preoperative information Explain the procedure Discuss potential side effects and complications Advise the patient about what to do after the procedure Document the discussion 2. Determine the patient’s neurological status Exclude neurological abnormalities 3. Exclude contraindications 4. Avoid premedication in outpatients (particularly in blocks in which there is an increased risk of intravascular injection—e.g., stellate ganglion or superior cervical ganglion) |
Anatomy, complications, and side effects 1. With rarely used regional blocks, the anatomic and technical aspects should always be studied again beforehand 2. Detailed knowledge of potential complications and side effects of a regional block and how to avoid them 3. Ability to control potential complications and side effects 4. Select the correct block techniques 5. Manual skill and good training on the part of the anesthetist |
Preparation |
1. Ensure optimal positioning of the patient 2. Always secure intravenous access 3. Check that emergency equipment is complete and fully functioning 4. Added vasopressors are contraindicated in pain therapy 5. Observe sterile precautions |
Safety standards when injecting larger doses of local anesthetics |
1. Carry out aspiration tests before and during the injection 2. Administer a test dose 3. Inject local anesthetics in incremental doses (several test doses) 4. Maintain verbal contact with the patient 5. Cardiovascular monitoring 6. Keep careful notes of the block |
The application of the anesthesiological methods described in the subsequent chapters of this book for temporary interruption of stimulus conduction in a nerve or nerve plexus requires the use of strictly established indications and the implementation of a coordinated therapeutic approach. In principle, these blocks can be administered for surgery, diagnosis, prognosis, and therapy [1].
Surgical blocks are administered with high-dose local anesthetics for targeted isolation of a specific body region in order to carry out an operation.
Diagnostic blocks using low-dose local anesthetics are appropriate for the differential diagnosis of pain syndromes. They allow the affected conduction pathways to be recognized and provide evidence regarding the causes of the pain. Diagnostic blocks can also be used to clarify the question of whether the source of the pain is peripheral or central.
Prognostic blocks allow predictions to be made regarding the potential efficacy of a longer-term nerve block, neurolysis, or surgical sympathectomy. They should also be used to prepare the patient for the effects of a permanent block.
Therapeutic blocks are used in the treatment of a wide variety of pain conditions. Typical examples of these are post-traumatic and postoperative pain, complex regional pain syndrome (CRPS) types I and II (reflex sympathetic dystrophy and causalgia), joint mobilization, postherpetic neuralgia, and tumor pain.
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