Severe respiratory depression after epidural morphine in a patient with myotonic dystrophy

Bilevel positive airway pressure therapy in a patient with myotonic dystrophy and postoperative respiratory failure: A case report

Respiratory failure is a common complication in patients with myotonic dystrophy (MD) and might be a presenting symptom in the perioperative setting. We report the case of a 59-year-old woman with MD who underwent open cholecystectomy and developed postoperative respiratory failure. Without reintubation, the patient was successfully managed with bilevel positive airway pressure (BiPAP) and was discharged uneventfully. BiPAP may be considered as an alternative for postoperative respiratory failure in patients with MD. Careful observation of patients' postoperative condition and an earlier application of BiPAP are instrumental in avoiding retracheal intubation, which may cause further serious problems in patients with MD.

Opioid-free general anesthesia in patient with Steinert syndrome (myotonic dystrophy): Case report

INTRODUCTION

We report on the anesthetic management using opioid-free method of a patient with Steinert syndrome (myotonic dystrophy, MD), autosomal dominant dystrophy which is characterized by consistent contracture of muscle following stimulation. A myotonic crisis can be induced by numerous factors including hypothermia, shivering, and mechanical or electrical stimulation. In patients with MD, hypersensitivity to anesthetic drugs, especially muscle relaxants and opioids, may complicate postoperative management. If opioids are employed (systemic or neuraxial), then ICU care and continuous pulse oximetry must be considered given the high risk for respiratory depression and aspiration. Patients with MD present high sensitivity to the usual anesthetics such as volatile and muscle relaxants (both depolarizing and nondepolarizing). Opioids may induce muscle rigidity in this type of MD. Therefore, omitting opioids is recommended. Due to hypersensitivity to opioids and increased susceptibility to intra- and postoperative complications, it is recommended to introduce opioid-free anesthesia (OFA), for example, with use of dexmedetomidine (DEX). This is a new method of conducting general anesthesia without opioids and is based on concept of multimodal approach to pain management.

METHODS

A 31-year-old male patient (183 cm, 69 kg) was scheduled for laparoscopic operation of cholecystectomy. The patient received intravenously (IV): propofol in a dose of 250 mg followed by continuous infusion, rocuronium in a dose of 20 mg, and DEX in a loading dose of 0.6 μg/kg over 10 minutes followed by continuous infusion of dose of 0.2 μg/kg/hour.

RESULTS

The course of anesthesia and postoperative period were uneventful. The patient exited the operating theatre in a good medical state, with vitals within normal limits and fully regained consciousness.

CONCLUSION

DEX is effective and safe for moderately painful procedures in patients with the elevated risk of respiratory and cardiovascular failure. This substance provides adequate analgesia level during surgeries of patients suffering from MD.

Functional and histopathological identification of the respiratory failure in a DMSXL transgenic mouse model of myotonic dystrophy

Acute and chronic respiratory failure is one of the major and potentially life-threatening features in individuals with myotonic dystrophy type 1 (DM1). Despite several clinical demonstrations showing respiratory problems in DM1 patients, the mechanisms are still not completely understood. This study was designed to investigate whether the DMSXL transgenic mouse model for DM1 exhibits respiratory disorders and, if so, to identify the pathological changes underlying these respiratory problems. Using pressure plethysmography, we assessed the breathing function in control mice and DMSXL mice generated after large expansions of the CTG repeat in successive generations of DM1 transgenic mice. Statistical analysis of breathing function measurements revealed a significant decrease in the most relevant respiratory parameters in DMSXL mice, indicating impaired respiratory function. Histological and morphometric analysis showed pathological changes in diaphragmatic muscle of DMSXL mice, characterized by an increase in the percentage of type I muscle fibers, the presence of central nuclei, partial denervation of end-plates (EPs) and a significant reduction in their size, shape complexity and density of acetylcholine receptors, all of which reflect a possible breakdown in communication between the diaphragmatic muscles fibers and the nerve terminals. Diaphragm muscle abnormalities were accompanied by an accumulation of mutant DMPK RNA foci in muscle fiber nuclei. Moreover, in DMSXL mice, the unmyelinated phrenic afferents are significantly lower. Also in these mice, significant neuronopathy was not detected in either cervical phrenic motor neurons or brainstem respiratory neurons. Because EPs are involved in the transmission of action potentials and the unmyelinated phrenic afferents exert a modulating influence on the respiratory drive, the pathological alterations affecting these structures might underlie the respiratory impairment detected in DMSXL mice. Understanding mechanisms of respiratory deficiency should guide pharmaceutical and clinical research towards better therapy for the respiratory deficits associated with DM1.

Malignant hyperthermia and myotonic disorders

Advances in physiology and molecular genetics have promoted greater understanding of the various clinical manifestations of muscle disorders. For example, myotonia or profound weakness may be observed in sodium channel disease (e.g., paramyotonia congenita or hyperkalemic periodic paralysis), depending on the specific channel defect or with slight changes in membrane potential. Observed effects of anesthetic techniques have been essential to elucidating the primary muscular nature of myotonia. Commonly used anesthetic medications have potentially lethal (e.g., MH) or serious (e.g., myotonic dystrophy) adverse effects. Conversely, lidocaine or propofol may have therapeutic benefit for patients with skeletal muscle sodium channel disorders. Additional investigation is required to improve our understanding of how age, gender, or other factors determine the phenotypic expression of malignant hyperthermia. Future research holds the promise for more accurate pre-anesthetic identification of persons with heritable myopathies, especially those who are asymptomatic. Enhanced awareness of multiple organ system involvement in myotonic dystrophy is essential for planning perioperative care. Patients with periodic paralysis require that we know factors that incite or inhibit the development of their attacks. Advances in bench research and detailed clinical studies will further improve our ability to provide optimal care for patients with muscle disorders.

Anaesthesia for caesarean section in a patient with myotonic dystrophy receiving warfarin therapy

A 31-yr-old parturient with myotonic dystrophy and asthma presented for elective Caesarean section. The patient was receiving warfarin having had two previous episodes of thromboembolism. Anticoagulation was subsequently provided by heparin in the weeks prior to delivery. The combination of the patient's medical conditions and the continuing need for anticoagulation presented a considerable anaesthetic problem in planning anaesthesia and analgesia for both elective and emergency delivery. Heparin was discontinued on the day prior to surgery and restarted immediately after surgery. During surgery flowtron anti-embolitic boots were used. Warfarin therapy was recommenced on the seventh postoperative day. Anaesthesia for Caesarean section was provided using a combined spinal epidural technique using a separate needle, separate interspace method. Postoperative pain was relieved by using a continuous epidural infusion, transcutaneous nerve stimulation and diclofenac. No new neurological problems arose despite the use of epidural analgesia in the presence of heparin anticoagulation. This method of providing anaesthesia and postoperative analgesia without the use of opioids in an anticoagulated, asthmatic, myotonic parturient has not been described elsewhere.