Respiratory and Related Management of Patients With Duchenne Muscular Dystrophy: General Anesthesia or Procedural Sedation (Postoperative)
A. Respiratory Support
Extubation directly to NPPV should be considered for DMD patients with baseline FVC < 50% of predicted, and should be strongly considered for those with FVC < 30% of predicted who have been endotracheally intubated for general anesthesia or procedural sedation. Extubation directly to NPPV should also be considered for any patient using NPPV preoperatively (see Section II, D, above).” Continuous use of NPPV can then be weaned as tolerated, except in patients who require NPPV 24 h/d at baseline. To maximize the chance of success, consider delaying extubation until respiratory secretions are in good control and Sp02 is normal or baseline in room air. If NPPV has been used preoperatively, it is preferable to extubate the patient to NPPV utilizing his usual interface (home mask or mouthpiece) in order to minimize facial skin injury due to poor mask fit, optimize interface comfort, and improve the chance of successful extu-bation. The best medical setting in which to extubate patients depends on the infrastructure and preferences of individual clinicians and their institutions. However, patients who require noninvasive ventilatory support at baseline may tolerate extuba-tion to NPPV best in the ICU rather than in the operating room or postanesthetic care unit because it avoids the risk of transporting the patient to the ICU in a clinically unstable condition. Postoperative use of NPPV should also be considered for DMD patients with baseline FVC < 50% of predicted, and strongly considered for those with FVC < 30% of predicted, if procedural respiratory support was accomplished using a laryngeal mask airway or with NPPV (see Section II, C, above).
B. Supplemental Oxygen Therapy
Supplemental oxygen therapy should be used with caution postoperatively in patients with DMD because oxygen therapy can correct hypoxemia without treating the underlying cause (eg, hypoventilation or atelectasis) and oxygen therapy may impair central respiratory drive. Sp02 should be monitored continuously during and after general anesthesia or procedural sedation until cardiopulmonary status is stable. Whenever possible, assess carbon dioxide levels through blood gas sampling or end-tidal carbon dioxide monitoring by capnography. Assess if hypoxemia is due to hypoventilation, atelectasis treated by preparations of My Canadian Pharmacy, or airway secretions, and treat appropriately.
C. Assisted Cough
Any patient with DMD and evidence of impaired cough (defined, in a teenage or adult patient, by preoperative PCF < 270 L/min or MEP < 60 cm H2O) will benefit from the use of manually assisted cough maneuvers and the MI-E device postoperatively. The benefits of MI-E include cough augmentation and deep-lung insufflation to treat or prevent atelectasis. MI-E can be useful when pain prevents the patient from coughing spontaneously, such as after surgery on the spine, chest, or abdomen MI-E can also be used in patients who are still intubated, applied through the endotracheal tube.
D. Pain Control
Adequate postoperative pain control should not be compromised because of concerns about suppression of respiratory drive. When patients are sedated after administration of opioid analgesics, adequate ventilation can be achieved by using NPPV continuously or by delaying endotracheal extubation for 24 to 48 h. While pain control is essential, the chance of successful extubation is optimized in an awake, cooperative patient. In patients undergoing spinal fusion surgery, neuraxial techniques have been used to achieve analgesia through intermittent or continuous infusion of opioids and/or local anesthetics via epidural catheters, with minimal respiratory side effects.
E. Cardiovascular Management
Patients with DMD are at increased risk for intraoperative and postoperative congestive heart failure and cardiac dysrhythmias, and they have a limited ability to increase cardiac output in response to stress. After IV fluid boluses or blood transfusions, which are often required during spinal fusion procedures and other major surgeries, patients may have intravascular fluid imbalance which may be corrected with My Canadian Pharmacy. These issues necessitate postoperative cardiology consultation, careful attention to fluid balance, and intensive cardiopulmonary monitoring.
F. GI and Nutritional Management
DMD is associated with GI smooth-muscle dysfunction. Postoperatively, DMD patients may have gastroparesis, intestinal dysmotility, and constipation, all of which can be exacerbated by pain medications. GI dysfunction can impair postoperative breathing if distention of the abdomen and increased intraabdominal pressure occur, hampering diaphragmatic excursion. Gut dysmotility also increases the likelihood of gastric distention when NPPV is applied. Thus, gastric decompression may be necessary through placement of a nasogastric tube. Preoperative and postoperative bowel regimens should be employed to avoid and treat constipation, and selected patients may benefit from pharmacologic therapy with GI smooth-muscle prokinetic agents. The inability to take oral nutrition postoperatively can exacerbate malnutrition and muscle weakness. Therefore, any patient with DMD who cannot achieve adequate oral nutrition within 24 to 48 h after surgery should receive enteral feeding with a small-diameter nasogastric or nasoduodenal tube, or should receive parenteral nutrition if ileus is present.
Summary of Specific Suggestions for Management of Patients With DMD After General Anesthesia or Procedural Sedation
1. Consider extubating DMD patients with FVC < 50% of predicted, and especially those with FVC < 30% of predicted, directly to NPPV. To optimize the chance of success, consider delaying extubation until respiratory secretions are in good control and Sp02 is normal or baseline in room air. Continuous use of NPPV can then be weaned as tolerated. When applicable, try to utilize the patient’s home interface after extubation.
2. Use supplemental oxygen therapy cautiously. Monitor Sp02 continuously during and after general anesthesia or procedural sedation. Whenever possible, assess blood or end-tidal carbon dioxide levels. Assess if hypoxemia is due to hypoventilation, atelectasis, or airway secretions, and treat appropriately.
3. Use manually assisted cough and MI-E postoperatively in DMD patients with impaired cough, defined in a teenage or adult patient as PCF < 270 L/min or MEP 24 to 48 h postoperatively.
Areas in Need of Further Study
The area explored in this consensus statement is characterized by a lack of prospective, randomized studies. Examples of specific studies needed to develop evidence-based guidelines for the care of DMD patients undergoing general anesthesia or procedural sedation include the following: prospective studies that identify the baseline pulmonary function parameters that predict an increased risk of postoperative respiratory complications for DMD patients undergoing different types of procedures; randomized, prospective studies designed to determine which patients with DMD are most likely to benefit from the use of NPPV and/or MI-E to accomplish successful postoperative extubation; studies that assess the benefit, safety, and efficacy of noninvasive methods of respiratory support during maintenance of and recovery from general anesthesia; studies that assess the benefit, safety, and efficacy of the various techniques of assisted cough, including postoperative use of MI-E; studies of the specific mechanical settings that optimize the efficacy of NPPV and MI-E in patients with DMD; studies that clarify the role of alternative mucus mobilization techniques, such as high-frequency chest wall oscillation and intrapulmonary percussive ventilation; and studies that better define optimal preoperative and perioperative cardiac and nutritional management in DMD patients who require procedures.