FEATURE ANAESTHESIOLOGY 065
tamponade can be unrecognized and present serious hemodynamic changes with induction of general anaesthesia. The long-standing RA patient should be interviewed to determine if there are any symptoms suggestive of diminished cardiac reserves. If in doubt, the definitive answer is a transthoracic echocardiogram. The spinal column in the RA patient can have deformity, decreased
range of motion, or fusion. Fusion can lead to osteoporosis causing structural weakening, presenting risk for fracture during positioning or airway manipulation. If neuraxial anaesthesia is planned, an A-P x-ray view of the pelvis may reveal an interspace that could be instrumented with success for spinal or epidural anaesthesia. The treatment of RA can present preoperative issues. Patients
on chronic steroid therapy should be considered to have adrenal suppression and stress-dose steroid given. Historically, intramuscular steroids were chosen, but the combination of the oral dose with intravenous doses before induction avoids the potential trauma of an intramuscular injection. Cytoxan is an anti-cell proliferation drug, which can be used in severe rheumatoid patients. This will decrease plasma cholinesterase, and prolong the action of succinylcholine and slow the metabolism of ester local anesthetics. The emotional consequences of
laryngeal opening due to unilateral arytenoid changes, caused by alteration of virtually every element of the endolarynx. Direct visualization of the larynx can be difficult, and may require special maneuvers to rotate the opening into view. In a small percentage of cases, fiberoptic visualization may be the only possible approach. Exacerbation of the laryngeal symptoms has been reported with the use of laryngeal mask airway (LMA) for airway management during anesthesia, with the need for tracheotomy. When combined, the difficulty with laryngoscopy due to decreased range of motion and the difficulty with direct visualization of the larynx can create extremely difficult airway management. There is increasing use of videolaryngoscopy to manage the rheumatoid airway. Instability based on incompetence of structural elements of the
cervical spine is a serious anaesthetic consideration. When synovial destruction creates incompetence of the transverse ligament, C1-C2 (atlanto-axial) instability can occur. While instability can develop at almost any level of the cervical spine due to destruction of synovial articulation, the most likely site is the weakening of the fixation (transverse ligament) of the axis of C2 to the ventral side of C1 or erosion of the odontoid at base of the axis. In either case, dorsal or
“When the inflammation is sustained, joint surface destruction, angulation, and/or fusion, depending on the structure of the joint, can occur”
the disease can cause depression, and these patients may be treated with chronic anti-depressant therapy. The tricyclic anti-depressants and mono-amine oxidase inhibitors (MAOI’s) have been used in the past. They are known to interfere with catecholamine activity, and exaggerated hypertension in repose to indirect-acting vasopressors is possible. Although the general trend is against pre-operative withdrawal of these drugs, many rheumatoid patients may have a mild depression, which can be temporarily controlled with other agents not associated with peri- operative hemodynamic consequences. If MAOI therapy is not stopped, the rare, but serious hyperpyrexic coma associated with the use of meperidine in patients on MAOI’s must be considered. If hypotension occurs during anaesthesia in patients on MAOI therapy, the first response should be fluid therapy, and subsequently, small trial doses of direct acting vasopressors (such as phenylephrine) should be attempted.
RHEUMATOID ARTHRITIS AND AIRWAY MANAGEMENT Due to the existence of synovial joints at a variety of locations, the management of the airway in RA patients is the most common and serious preoperative issue. The cervical spine, temporomandibular joint (TMJ) and the arytenoid bodies can have degenerative changes. The lack of mobility can be the primary presentation. When this is combined with decreased mouth opening due to TMJ involvement, suspicion of potential difficult airway management is greater. Less obvious, but equally challenging can be the results of rheumatoid disease on the larynx itself. Since the joints are synovial, rheumatoid disease can lead to joint degeneration. Cricoarytenoid arthritis in RA patients can present with severe dysfunction of the larynx, including stridor, requiring urgent tracheostomy. With variable attack of synovial elements of the larynx, the result can be an angulated
vertical translocation of C2 on C1 places the spinal cord at risk. Less commonly, upward movement of the odontoid toward the brain stem can also occur with erosion of the base of the odontoid. Atlanto-axial instability can be pain-free, but it can also present with radiculopathy, long-tract signs, or even severe myelopathy in patients with normal or limited range of motion of the neck. Some patients even have a clunking sensation with certain types of movement, which represents acute subluxation of the cranium and C1 onto C2. Some patients will report long tract signs with certain types of movement, especially neck extension. Neck extension is most likely to elicit neurological signs because extension induces dorsal subluxation of C2, encroaching on the spinal cord. The optimum position for the neck depends of what type of instability is present, and is different for vertical atlantoaxial instability (AAI) compared to the more common horizontal AAI. Fluoroscopic guidance has been used for optimum position for airway management in RA patients. In many cases, instability of the neck is known in advance, especially in those patients who present for elective or urgent stabilization. When early instability is identified, it is assumed that progression will occur. Documentation with forced flexion-extension neck x-rays is indicated prior to anaesthesia, unless surgical fusion has been confirmed. Conventional airway management involves extension of the occiput on the neck and flexion of the cervical spine, with trauma to spinal cord as a risk in the presence of instability. Simple lateral films are not adequate, since instability may only present with movement. Even in patients with prior surgical fusion of C2 to occiput, flexion-extension views can identify a fusion dependent solely on the wires, which could be disrupted during airway management. Incompetence of the base of the odontoid is detected with open mouth, A-P x-ray viewing. The preoperative dilemma occurs when the RA patient without
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