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Grand Rounds May 10, 2006

Grand Rounds May 10, 2006. Derek R. Seiler, M.D. George J. Sheplock, M.D. Case Report. 5 yr old male, 19 kg Laparoscopic splenectomy secondary to hereditary spherocytosis Exam unremarkable Healthy except for baseline HCT 27.6

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Grand Rounds May 10, 2006

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  1. Grand RoundsMay 10, 2006 Derek R. Seiler, M.D. George J. Sheplock, M.D.

  2. Case Report • 5 yr old male, 19 kg • Laparoscopic splenectomy secondary to hereditary spherocytosis • Exam unremarkable • Healthy except for baseline HCT 27.6 • Hematologist seen pre-op and stated “no contraindications for surgery” • Vitals signs unremarkable, Temp 36.9 C

  3. OR • Inhalational Induction with nitrous, sevo, oxygen • IV access obtained • Mivacurium 6mg, uneventful tracheal intubation • Fentanyl (5ug/kg in incremental doses), oxygen, vecuronium (0.1mg/kg) and isoflurane • Ventilation with TV 200ml, RR 13 and EtCO2 ranged 31-37 • Esophageal Temp ranged from 36.9-37.6 C

  4. To PACU • Case Summary • 360 ml IV Fluid • Clear urine 60ml, EBL 45ml and surgical time was 74 without complication • After assessment using nerve stimulator: • 1mg neostigmine, 0.2mg glycopyrulate • Awake, moving all 4 limbs, extubated and taking to PACU with O2 via face-mask - no pulse oximeter(departmental policy) by anesthesia resident

  5. Arrival to PACU • Upon arrival – crying, calling for mother, and trying to remove NGT when…. • Suddenly collapsed and became apneic • EKG showed HR <50 • Previously healthy child, What happened?

  6. Later in PACU • PALS Protocol Initiated • Re-intubated without incident • 10 min later femoral arterial line obtained, ABG: • PH 7.237, pCO2 18.4, pO2 429, HCO3 7.6, Na 130, K 9.2, HCT 26 • Temp unchanged, no rigidity • any New thoughts?

  7. Later in PACU • PALS Protocol Initiated • Re-intubated without incident • 10 min later femoral arterial line obtained, ABG: • PH 7.237, pCO2 18.4, pO2 429, HCO3 7.6, Na 130, K 9.2, HCT 26 • Temp unchanged, no rigidity • Following appropriate treatment, K was reduced to 7.0 and after 45 min CPR patient regained NSR. • “Electrolytes and acid-base status normalized over several hours.”

  8. DDX • Respiratory • Common cause of cardiac arrest in children • No Sx of obstruction, stridor, or laryngospasm • Easy to ventilate and intubate • Authors initially thought rx-related or cardiac • Iatrogenic – no K+ solutions available • No cardiac hx and no evidence of electrical imbalance such as prolonged QT/Torsades • VSS & Slight Temp increase intraop • No symptoms of hyperkalemia on intra-op EKG • No succinycholine used

  9. Further Investigation • Pre-operative blood sample was sent for CK and K+. • 15,000 U/l and 5.0 mmol/l respectively • CK rose to 128,789 U/l next day and urine was positive for myoglobin • EEG declared brain death on POD 7 • Muscle bx returned positive for DMD • Additional discussion with parents revealed no history or symptoms

  10. Etiology • Perianesthetic Rhabdomyolysis with Hyperkalemia • Also known as Anesthesia Induced Rhabdomyolysis (AIR) • Mechanism unclear

  11. Not Unique • 6th REPORTED case of hyperkalemic arrest without succinylcholine • Previous 5 reported cases had no h/o DMD, had uneventful intraop course with VA, all developed hyperkalemia and rhabdomyolysis postop in PACU, 3 had cardiac arrest. • Mild Becker’s with K+ reaching 12 mEq/l • One within 10 minutes of induction • Similar case 15 minutes into recovery room • Others previously asymptomatic individuals

  12. Duchenne’s Overview • Muscular dystrophy is a term used to define a group of degenerative genetic diseases progressively affecting skeletal muscles, with no motor neuron abnormality. • Duchenne muscular dystrophy, also called Pseudohypertrophic Muscular Dystrophy, is the most common among muscular dystrophies. • The defect in dystrophinopathies such as DMD, results from lack of membrane stabilizing protein dystrophin. See Figure next slide:

  13. Duchenne’s Overview • Caused by mutations in the short arm of chromosome X, DMD affects mainly boys, who inherit the disease from their mothers (X-linked recessive); women are in general asymptomatic. • Disruption of cell membrane causes influx of Ca+ and eventual muscle cell degeneration. • Incidence is 3 to every 10,000 live births.

  14. Symptoms • This disorder is typically diagnosed after 2 years of age (2-5 yo), when signs and symptoms, such as muscle weakness, start to become evident. • Symptoms start in hips, pelvic region, thighs and shoulders, with pseudodystrophy of several muscle groups, such as calf muscles, because of fatty infiltration. • CK is 30-300x normal, 70% of carriers have increased levels as well. • Diagnostic is confirmed by muscle biopsy.

  15. Prognosis • It is a progressive disease which may end up affecting all skeletal muscles, including respiratory and cardiac muscles. • DMD patients seldom live beyond 30 years of age. • Wheelchair bound by 8-11 years of age • Severe pulmonary infections are the major cause of mortality along with congestive heart failure secondary to worsening cardiomyopathy.

  16. Board Review Pause • According to the ABA, from the 1995 ITE, more than ½ of CA-3 residents failed to assess cardiac status during preoperative assessment of a 12-year-old patient with Duchenne’s muscular dystophy who is unable to ambulate.

  17. PE Warning Signs • History of motor delay should be explored • Did patient learn to walk with peers • Gait problems/ Falls / Fatigue • Climbing/Descending Stairs • Gower’s sign • Inability to get up from floor without using upper extremities • Enlarged muscles • Family History • Only 10% lack a family history

  18. Calf Hypertrophy Not Specific

  19. Physiologic Changes • Mainly pulmonary and cardiac functions. • Studies have shown that 83% of these patients have ECG abnormalities • Tall R Waves in V1, deep Q waves in limb leads, short PR interval. • Loss of R wave amplitude in lat leads reflects degeneration of myocardial tissue • 26% present heart failure • 31% have chest X-rays changes • 73% have severe pulmonary restriction. • Very often, these patients develop dilated cardiomopathy which may be associated to mitral valve incompetence (papillary muscle dysfunction) (25% of cases). Le Corre F, Plaud B - Neuromuscular disorders. Curr Opin Anesthesiol, 1998;11:333-337

  20. Physiologic Changes • Cardiac arrhythmias and electric conduction defects are also common. • Kyphoscoliosis is another frequent condition, causing pulmonary restriction and very often requiring surgical treatment. • Decreased laryngeal reflexes and prolonged gastric emptying time increase the risk of aspiration and should be considered "full stomach" patients. • Fever, rhabdomyolysis (hyperkalemia, myoglobinuria) and masseter spasm are complications described during anesthetic induction of these patients. • Thought to be at increased risk of MH

  21. Anesthetics Agents and DMD • The FDA banned succinylcholine for DMD patients after the observation of several rhabdomyolysis cases and cardiac arrest by hyperkalemia. • Regional anesthesia could be a good alternative, when possible, for minimally depressing respiratory and cardiovascular systems and requiring minor airway manipulation. • Total intravenous anesthesia may be used, provided care is taken with cardiac depression caused by some agents, and with individual sensitivity to respiratory depression. • Increased sensitivity for nondepolarizing neuromuscular blockers. (Mivacurium probably normal).

  22. History of DMD and Anesthesia • 1994 FDA issued warning against ROUTINE use of succinycholine in infants and children • Succinycholine causes hyperkalemia in DMD • Others have shown succinycholine and VA as cause of cardiac arrest in DMD • Volatile agents have wide and safe use in DMD patients

  23. Recent Developments • Incidence of anesthetic complications • MH is probably not increased • Understanding of AIR • AIR risk changes as disease progresses • Not all volatile agents may be the same • Resuscitation Differs

  24. Incidence of Anes Complications • Breuking E et al, Anaesthetist 2000 • Questionaires to all DMD/BMD families who were treated in a “Muscle Center” from 1983-2000 • 147 DMD families, 53 BMD families with 212 male and 9 female patients

  25. Incidence, cont. • 444 anesthetics • 6 cardiac arrests (asystole) and additional 9 rhabdomyolysis cases • 2 cases without succinylcholine, 2 cases with unknown muscle relaxant • Clear increase in frequency over normal pediatric population

  26. MH vs. AIR • Shift of opinion? • Evidence suggests DMD & MH independent • Malignant Hyperthermia vs. Anesthesia-Induced Rhabdomyolysis • Common Clinical/Biochem Characteristics • hyperkalemia, • metabolic acidosis • myoglobinuria • elevated creatinine kinase

  27. Mechanism of Action of AIR • Anesthetic agents stress a muscle cell membrane that is already ‘fragile’ or ‘unstable’ because of the lack of dystrophin. • Increased membrane permeability results in a compensatory hypermetabolic response in an attempt to re-establish membrane stability and prevent calcium ion fluxes. • Rhabdo involves breakdown of this membrane, resulting in loss of cell contents (myoglobin, K, CK) • VA are likely therefore one factor that must come together to result in rhabdomyolysis Gronert GA, Fowler W, Cardinet GH III, Grix A jr, Ellis WG, Schwartz MZ. Absence of malignant hyperthermia contractures in Becker–Duchenne dystrophy at age 2. Muscle Nerve 1992; 15: 52–6

  28. Timing • A relatively large number of cases occur during recovery from anesthesia • Trigger or precipitating event may simply be movement • Destabilization may occur during high levels of volatile agents intraoperatively • Destablization may occur at very low MAC levels in the PACU • Exceptions

  29. AIR Risk • Different risk for undiagnosed or recently diagnosed DMD patients? • In early phases (less than 8 years of age), unstable muscle fibers attempting to regenerate • These are most prone to rhabdomyolysis • Older, more severely affected children may have more uneventful anesthetics with volatile agents and with succinylcholine. Yemen T: Muscular dystrophy, anesthesia and the safety of inhalational agents revisted, again. Pediatric Anesthesia 2006 16: 105-108

  30. Agent Differences • Sevoflurane may be best • Less potent stimulus for release of calcium from SR • It may be this release of Ca+ that produces muscle membrane damage and AIR • Therefore, less of a trigger in theory Kunst G, Graf BM, Scheiner R et al: Differential effects of sevoflurane, isoflurane, and halothane on Ca2+ release from the sarcoplasmic reticulum of skeletal muscle. Anesthesiology 91:179, 1999

  31. Resuscitation • Different mechanism -> Different outcome • Receptor Upregulation • A presumably finite opening of acetylcholine receptor channels with an intact membrane • Challenge of CPR reduced once K+ channels close • Rhabdomyolysis • Continued loss of K+ from multiple affected muscles secondary to membrane instability • LARGE K+ release may exceed capacity for redistribution Gronert, GA Cardiac Arrest after Succinylcholine: Mortality Greater with Rhabdomyolysis Than Receptor Upregulation. Anesthesiology 2001; 94 (3) 523-526

  32. Cardiac Arrest after Sux Gronert: Anesthesiology; Volume 94 (3). March 2001. 523-529

  33. What’s the Best Answer? • No large prospective trials • TIVA opinion is rapidly gaining in popularity • 24th Pediatric Anesthesia Conference • Toronto, November 2005 • “TIVA should probably be used and anesthetic vapours avoided” Dr. Jason A Hayes, The Hospital for Sick Children, The University of Toronto

  34. Support Groups’ OpinionMDA.org and Parent Project • “General anesthesia is accompanied by a number of important risks. When general anesthesia is required in order to undergo a specific procedure succinylcholine and inhalational anesthetics need to be AVOIDED.” Parent Project, Muscular Dystrophy Website (“By Dr. Margaret Vroom, Anesthesiologist”) http://www.parentprojectmd.org

  35. DMD Summary • DMD has significant anesthetic implications. • Thorough Hx & PE cannot be overstated. • In DMD Rhabdomyolysis is a potential complication not restricted to the use of succinylcholine. • In event of sudden cardiac arrest in apparent healthy child must be alerted to possibility of hyperkalemia and undiagnosed DMD. • In DMD mechanism of hyperkalemia secondary to AIR, not necessarily MH. • Succinycholine should be avoided in DMD. • Perhaps ROUTINE use of VA, especially in younger patients with DMD, should be avoided.

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