8. CPT codes 64400-64530 describe injection of anesthetic agent for diagnostic or therapeutic purposes, the codes being distinguished from one another by the named nerve and whether a single or continuous infusion by catheter is utilized. All injections into the nerve including branches described (named) by the code descriptor at a single patient encounter constitute a single unit of service(UOS). For example:
(1) If a physician injects an anesthetic agent into multiple areas around the sciatic nerve at a single patient encounter, only one UOS of CPT code 64445 (injection, anesthetic agent; sciatic nerve, single) may be reported.
(2) If a physician injects the superior medial and lateral branches and inferior medial branches of the left genicular nerve, only one UOS of CPT code 64450 (Injection, anesthetic agent; other peripheral nerve or branch) may be reported regardless of the number of injections needed to block this nerve and its branches.
Opioids, which can be naturally occurring, semisynthetic or synthetic compounds, produce analgesic effects by binding to opioid receptors in the central nervous system. Several different opioid receptors have been identified and, based on their interactions with these receptors, opioids fall into three main categories:
Pure agonists – drugs that bind to and stimulate opioid receptors, and are capable of producing a maximal response
Partial agonists – drugs that stimulate opioid receptors but have a ceiling effect, . produce a submaximal response compared with an agonist
Mixed agonist-antagonists – drugs that are agonists for one opioid receptor but antagonise other opioid receptors.
Opioids are also classified as being ‘strong’ or ‘weak’, depending on the strength of their clinical effect, which has historically been measured against the effect of morphine.
Some opioids and their classifications are listed below:
Goals for anesthesia for cesarean delivery (CD) must include the comfort and safety of the parturient, and the well-being of the fetus and neonate. This topic will discuss the management of regional and general anesthesia for CD. Regional anesthesia techniques, adverse effects of neuraxial anesthesia, and neuraxial labor analgesia are reviewed separately. (See "Spinal anesthesia: Technique" and "Neuraxial analgesia for labor and delivery (including instrumented delivery)" and "Adverse effects of neuraxial analgesia and anesthesia for obstetrics" and "Epidural and combined spinal-epidural anesthesia: Techniques" .)