SPRING 2010

Open Globe Repair for General Anesthesia in Patient with Mitochondrial Myopathy, OSA and Room Air Oxygen Saturation 88%

Carol Craig CRNA, Charlie Reed CRNA, Myra Aultman CRNA, John Parker MD, Gwendolyn Boyd MD
University of Alabama at Birmingham, Callahan Eye Foundation Hospital

ASA Medically Challenging Case

Abstract

A 70 y/o female was scheduled for amniotic membrane placement over a recurrent perforated corneal ulcer. Co-morbidities included: mitochondrial myopathy, pulmonary hypertension, OSA compliant with CPAP, DVT with PTE, CML status post bone marrow transplant in remission, but with chronic graft versus host disease, CAD status post PTCA and stent, small pericardial effusion, depression and anxiety as well as persistent cough. The patient stated her mitochondrial myopathy had caused her to have "weak breathing muscles." The surgeon stated since it was an open globe, he would need general anesthesia. Management will be discussed.

What is Mitochondrial Myopathy?

The National Institute of Neurological Disorders and Strokes [1] defines mitochondrial myopathy as a group of neuromuscular diseases caused by damage to the mitochondria—small, energy-producing structures that serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy, and thus appear to be particularly damaged when mitochondrial dysfunction occurs. Some of the more common mitochondrial myopathies include Kearns-Sayre syndrome, myoclonus epilepsy with ragged-red fibers, and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes.
The symptoms of mitochondrial myopathies include muscle weakness or exercise intolerance, heart failure or rhythm disturbances, dementia, movement disorders, stroke-like episodes, deafness, blindness, droopy eyelids, limited mobility of the eyes, vomiting, and seizures. The prognosis for these disorders ranges in severity from progressive weakness to death. Most mitochondrial myopathies occur before the age of 20, and often begin with exercise intolerance or muscle weakness. During physical activity, muscles may become easily fatigued or weak. Muscle cramping is rare, but may occur. Nausea, headache, and breathlessness are also associated with these disorders.

Although there is no specific treatment for any of the mitochondrial myopathies, physical therapy may extend the range of movement of muscles and improve dexterity. Vitamin therapies such as riboflavin, coenzyme Q, and carnitine (a specialized amino acid) may provide subjective improvement in fatigue and energy levels in some patients. The prognosis for patients with mitochondrial myopathies varies greatly, depending largely on the type of disease and the degree of involvement of various organs. These disorders cause progressive weakness and which may subsequently lead to death.

Amniotic Membrane Transplants

The amniotic membrane is "harvested" at the time that a baby is born, when it is no longer needed to sustain the baby. The amniotic membrane, which surrounds the fetus in the womb, is a unique source of 'biological dressing' that has been used in wound healing for decades. These membranes appear to contain large amounts of growth factors (which encourage tissue regeneration), as well as anti-bacterial and anti-scarring properties. They are especially useful as tissue grafts because they do not encourage autoimmune rejection (as happens in organ transplantation, for example). Amniotic membrane transplants have also been successful in promoting the growth of corneal tissue and in preventing corneal scarring. Within two months, the amniotic membrane tissue "dissolves," leaving healed corneal tissue in its stead. [2]

This type of surgical intervention may be performed in situations in which spontaneous healing of the surface of the cornea fails to occur, such as in cases of chemical burns, or where the cornea is severely infected. It is not usually the procedure of choice when the cornea is severely damaged, such as when large perforations occur. It was chosen in this circumstance because of the persistent, recurring nature of the patient’s corneal perforations.

Case Report

A 70 year old female presented for repair of persistent perforated corneal ulcer secondary to graft vs host disease following a bone marrow transplant seven years previously for CML, now in remission. Additionally, the patient had cicatrizing conjunctivitis with bilateral symphepharon.

Her comorbidities included biopsy proven mitochondrial myopathy with PFTs shown in figure 2. In addition, she had CAD with PTCA 13 years PTA, OSA compliant with CPAP, DVT and PTE three years PTA with secondary pulmonary hypertension, history of chronic kidney disease, esophageal spasms treated with nitroglycerin, chronic sinusitis with possible CSF leak, and depression. Her neurologist wrote that she also had symptoms of Eaton-Lambert in addition to the mitochondrial myopathy.

Medications included: Cellcept, mestinon, oxycodone, Lyrica, Tricor, doxepin, Nexium, NitroQuick prn, Zoloft, Cipro, PenVeeK, Fosamax, vitamins, fish oil, and Co-Q-10.

Transthoracic echocardiogram moderate tricuspid regurgitation, high normal PAP (no change from two years ago) normal LEF and REF, and a small pericardial effusion. ECG revealed NSR with ST changes consistent with lateral ischemia. Labs were normal including electrolytes, CBC, and creatinine 0.9.

Two Corneal Perforations

Patient’s Pulmonary Function Tests

Anesthetic Plan

Although GETA had been requested, due to her pulmonary status MAC with topical anesthesia was planned instead. Cataract surgery had gone well three months previously with divided doses of midazolam and fentanyl, totaling 1.5 mg and 75 mcg respectively.

Codeine 15 mg IV was given in the pre-op area for her persistent cough. Ketamine and midazolam were planned for sedation with topical lidocaine jelly. Ketamine’s minimal effect on the central respiratory drive is reflected by an unaltered response to CO2. It is also a bronchial smooth muscle relaxant. When given to patients with reactive airway disease and bronchospasm, pulmonary compliance is improved  [3]. In addition, ketamine stimulates the CV system and is usually associated with mild increases in BP, HR and CO. These hemodynamic changes are not related to the dose of ketamine (i.e., there is no hemodynamic difference between the administration of 0.5 and 1.5 mg/kg IV). Ketamine produces dose-related unconsciousness and analgesia. The concomitant use of benzodiazepines permits a lower dose requirement for ketamine while reducing emergence reactions.

Intraoperative Management and Postoperative Course

Upon arrival in the OR baseline oxygen saturation off oxygen was 89%. Nasal oxygen at 4 liters was begun using a capnographic nasal cannula. Initially, 1 mg midazolam and 50 mcg fentanyl were administered followed by 20 mg ketamine. Surgery lasted19 minutes and totals were 3 mg midazolam, 50 mcg fentanyl, and ketamine30 mg. Following recovery she was maintained on 2 liters oxygen overnight and discharged home the next day without complications.

Two weeks later the patient presented again for amniotic membrane placement. She stated she was very pleased with her previous anesthetic and similar was planned for this surgery. Codeine 15 mg was again administered for persistent cough. This time on arrival to the OR vital signs were: BP 156/84; HR 70; Sat 81% on RA. She was placed on O2 via NC 4L/m and the O2 sat increased to 94%. IV sedation was started with midazolam 1 mg, then 0.5 mg and ketamine 10 mg IV and repeated with midazolam 0.5 mg and ketamine 10 mg immediately prior to the procedure. She received topical anesthesia with lidocaine jelly to the eye prior to the prep and drape. At 1800 she received a 2nd dose of codeine 15 mg to prevent coughing. Her O2 saturation remained from 94-99% throughout and HR ranged from 80-90 in NSR throughout. Her BP ranged from 145/85 prior to the ketamine administration and then remained 170-185/85-95 throughout the case. She was awake and alert in the PACU, although oxygen was continued. Again she was observed overnight without complaint or complication.

References

1. The National Institute of Neurological Disorders and Strokes; http://www.ninds.nih.gov/disorders/mitochondrial_myopathy/mitochondrial_myopathy.htm#What_is

2. Corneal Transplant with amniotic membranes
http://www.peposevision.com/page.php?p=44#5

3. Ronald D. Miller; Miller’s Anesthesia, 6th Edition; 2005 pp. 346-350.

Presented at the Annual Meeting of American Society of Anesthesiologists Medically Challenging Case Section held in Orlando, Florida, October, 2008