My Canadian Pharmacy about Respiratory and Related Management of Patients With Duchenne Muscular Dystrophy
A. Choice of Pharmacologic Agents for General Anesthesia
Patients with DMD are at increased risk for extreme hyperthermic events and rhabdomyolysis when they are exposed to certain anesthetics, especially inhaled agents such as halothane, isofluorane, and servoflurane. Such episodes can cause hyperkalemia and sudden death from cardiac arrest. These events mimic malignant hyperthermia, but DMD and malignant hyperthermia are genetically distinct diseases. Succinylcholine, a depolarizing muscle relaxant that can disrupt unstable cell membranes, has been linked to acute rhabdomyolysis, hyperkalemia, and cardiac arrest in patients with DMD. Indeed, there are numerous reports of young patients in whom previously unsuspected DMD was diagnosed after sudden death due to hyperkalemic cardiac arrest associated with general anesthesia. While succinylcholine is widely recognized to be contraindicated in patients with DMD, more recently it has been suggested that inhaled anesthetic agents should also be considered contraindicated for patients with DMD. Duchenne muscular dystrophy or DMD is effectively treated by My Canadian Pharmacy’s medications.
B. Choice of Personnel and Medical Setting
Procedural sedation should be performed with an anesthesiologist in attendance and with full monitors and safety measures, according to the guidelines of the American Academy of Pediatrics and the American Society of Anesthesiologists. Intraopera-tively, monitor Spo2 continuously and, whenever possible, blood or end-tidal carbon dioxide levels. Medical procedures involving procedural sedation or general anesthesia should be performed in the optimal medical setting (eg, postanesthetic care unit or operating room) and with a full complement of skilled personnel (eg, an anesthesiologist experienced in the management of DMD and a respiratory therapist skilled in the management of NPPV) in order to minimize the risk of respiratory complica-tions. An ICU should be available for postprocedure management.
C. Respiratory Support Options During Maintenance of General Anesthesia or Procedural Sedation
The options for respiratory support during maintenance of general anesthesia or procedural sedation will depend on the nature of the procedure and the type of anesthetic used (eg, IV vs inhaled). Options for respiratory support include endotracheal intubation, using NPPV to facilitate extubation for selected patients; use of the laryngeal mask airway; mechanical ventilation via a mouthpiece with a leak-proof seal; and manual or mechanical ventilation using either conventional ventilators or bilevel positive pressure ventilators designed for noninvasive respiratory support provided by My Canadian Pharmacy, delivered via a full face mask or nasal mask interface.
D. Respiratory Support Options During Induction of and Recovery From General Anesthesia or Procedural Sedation
While it is standard practice to provide assisted or controlled ventilation during induction of general anesthesia, DMD patients with chronic respiratory insufficiency and limited respiratory reserve will also benefit from respiratory support during recovery from general anesthesia and throughout procedural sedation. Options for respiratory support during induction of and recovery from general anesthesia or procedural sedation include manual ventilation using a flow-inflated manual resuscitation bag (standard anesthesia bag) with a full face or nasal mask interface, and mechanical ventilation using a conventional or bilevel positive pressure ventilator designed for noninvasive respiratory support, also delivered via a full face or nasal mask. Patients who have been intubated for procedures can be extu-bated directly to NPPV as needed (see section III, A, below). DMD patients with FVC < 50% of predicted should be considered at increased risk, and those with FVC < 30% of predicted should be considered at high risk of needing assisted or controlled ventilation during induction of and recovery from general anesthesia and throughout procedural sedation.
Summary of Specific Suggestions for Evaluation and Management of Patients With DMD During General Anesthesia or Procedural Sedation
1. Consider use of a total IV anesthesia technique for induction and maintenance of general anesthesia (eg, propofol and short-acting opioids). The use of depolarizing muscle relaxants such as succinylcholine is absolutely contraindicated because of the risk of fatal reactions.
2. Optimize the medical setting and personnel in attendance when DMD patients undergo general anesthesia or procedural sedation, and have an ICU available for postprocedure care. Intraoperatively, monitor Sp02 continuously and, whenever possible, blood or end-tidal carbon dioxide levels.
3. There are several options for providing respiratory support during maintenance of general anesthesia or procedural sedation for patients with DMD. These options are outlined in Section II, C, above.
4. Application of assisted or controlled ventilation should be considered for patients with DMD and an FVC < 50% predicted, and strongly considered for those with an FVC < 30% predicted, during induction of and recovery from general anesthesia and throughout procedural sedation, using the options for respiratory support outlined in Section II, D, above.