TSRC 37th Annual Convention Critical illness Myopathy & Critical illness Polyneuropathy

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TSRC 37th Annual ConventionCritical illness
Myopathy Critical illness Polyneuropathy

• By Elizabeth Kelley Buzbee AAS, RRT, NPS
• Lone Star System- Kingwood formerly known as
  Kingwood College

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Failure to wean due to muscle weakness

• The effect of invasive mechanical ventilation on
  the patients ventilatory skeletal muscles is a
  well-known yet fairly complex problem.
• Full ventilatory support can trigger muscle
  atrophy within 72 hours in adults. According to
  MacIntyre, both muscle mass and cross-section of
  muscle fibers are affected. MacIntyre pp.
  1http//www.medscape.com/viewarticle/514526
• There is.. evidence of oxidative stress and
  protein breakdown in the muscles. MacIntyre pp.
  1
• When a patients FRC is raised above normal by
  PPV, the effect on resting muscle length results
  in a decrease in muscle strength. MacIntyre pp.
  1
• Alterations in the blood flow to the ventilatory
  muscles secondary to PPV just adds to the
  problem. MacIntyre pp. 1
• Not only is muscle strength affected, we will see
  a decrease in muscle endurance. MacIntyre pp. 1

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Other problems are more subtle

• malnutrition electrolyte imbalances
• The effects of malnutrition on the pulmonary
  system are distinct and well known.
• Patients who cannot take oral nutrition may be
  on IV glucose, which is fine for a day or so, but
  TPN with its more complete nutritional support is
  needed to keep metabolism going.
• Carbohydrates are needed for both the diaphragm
  and the myocardium Peters pp. 350
• The effect of electrolyte imbalances on the
  myocardium is well-known but potassium levels can
  also affect skeletal muscle action of the chest
  and abdominal muscles.
• Hypokalemia can cause muscle weakness even
  paralysis Garth
• while hyperkalemia also results in muscle
  weakness and flaccid paralysis
• serum magnesium levels of 8.0-10.0 mEq/L are
  associated with flaccid skeletal muscle
  paralysis. Novello

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The new threat in the ICU

• There are new problems discovered in the ICU that
  result in various degrees of muscle
  weakness--even paralysis-- that can keep a person
  from weaning off mechanical ventilation Dhand
  pp. 1025
• But is this a new problem? A review of the
  literature shows that as early as the 1970s, a
  small number of severe asthmatic patients who
  were intubated, paralyzed and ventilated had
  significant, generalized muscle weakness.
• Critical illness polyneuropathy
• Critical illness myopathy
• Prolonged neuromuscular blockage

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Occurrence of CIP, CIM or a combination of the two

• as many as 30-50 of patients with critical
  illness. Dhand pp. 1026
• Another study n206 found 25 of critical care
  patients who had been mechanically ventilated for
  more than 7 days had a degree of muscle weakness.
  This study included only persons who were awake
  and responsive Deems pp. 1043

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Critical illness myopathy
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Critical illness myopathy

• According to the American College of
  Rheumatology, myopathy is a disease of the
  muscles. The actual manifestation of the muscle
  disease varies widely based on etiology and the
  location of the defect.
• In the case of CIM, we seem to have a syndrome of
  symmetric weakness of all extremities, of muscle
  wasting, hyporeflexia and failure to wean from
  mechanical ventilation. Dhand pp. 1036

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Risk factors for Critical illness myopathy

• Persons who have received high levels of
  corticosteroids neuromuscular blocking agents
• for diseases such as severe asthma, COPD
  exacerbation, sepsis, ARDS and s/p organ
  transplants. Dhand pp. 1036

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S/S of Critical illness myopathy

• Inspection and interview of the patient
• There also seem to be is little in the inspection
  and interview to differentiate between critical
  illness myopathy and critical illness
  polyneuropathy.
• The patient will c/o weakness in both situations.

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S/S of Critical illness myopathy

• Serum Creatine Kinase
• a product of muscle damage. Need to differentiate
  between myocardial CK and skeletal muscle CK.
  Egans pp. 351
• Normal levels of serum creatine kinase are
  usually between 25 and 200 U/L. This test is not
  specific for the type of CK that is elevated.
  http//en.wikipedia.org/wiki/Creatine_kinase
• Serum creatine kinase may be 10-100 x higher than
  normal in CIM in the first 3-4 days-- then
  stabilize after 10 days. Dhand pp. 1028

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S/S of Critical illness myopathy

• EMG the electromyogram
• . There are two basic techniques
• One can study a specific muscle fibers reaction
  to the insertion of a needle electrode in a
  particular muscle fiber.
• A less-invasive procedure uses a surface
  electrode to monitor the general picture of
  muscle activation. During this study the patient
  has auditory or visual stimuli to help them know
  when they are activating the muscle. Again the
  action potential is measured
• http//en.wikipedia.org/wiki/Electromyography
• It is possible to perform an EMG of the phrenic
  nerve by placing the percutaneous electrode onto
  the neck at the supraclavicular fossa and
  measurements will be made at two spots along the
  anterior rib cage,
• but the presence of a central line in either neck
  will make this EMG impossible. Dhand pp.
  1031-1032

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S/S of Critical illness myopathy

• EMG results
• In myopathic disorders there will be decreases in
  duration of the action potential,
• and in the ratio of area to amplitude and in the
  number of motor unit in the muscles worse cases
  only http//en.wikipedia.org/wiki/Amplitude

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S/S of Critical illness myopathy

• Nerve conduction study
• In the nerve conduction study the patient is
  given an electrical shock at various spots along
  a nerve.
• Among other measurements, the velocity of the
  nerve conduction is measured at different points,
  as is the intensity of the response amplitude.
  The tester will study both the motor and the
  sensory nerve conduction. http//en.wikipedia.org/
  wiki/Nerve_conduction_study
• In the case of CIM, there should be no real
  problems with conduction

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S/S of Critical illness myopathy

• Problems w/ Nerve conduction studies
• in the ICU
• the patients skin temperature will change the
  speed of conduction cool bodies result in slow
  conduction
• and the presence of pacemakers indwelling
  defibrillators can make for difficulties
  MedlinePlus nerve conduction studies
• Picture of NCS http//0-www.nlm.nih.gov.catalog.l
  lu.edu/medlineplus/ency/imagepages/9743.htm

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S/S of Critical illness myopathy

• What are we left with?
• Muscle and nerve biopsy
• Both muscle and nerve biopsy can differentiate
  between CIP and CIM and even combinations of both
  disorders. Dhand pp.1033

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Critical illness polyneuropathy
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Critical illness polyneuropathy

• The Merck manual describes polyneuropathy as the
  simultaneous malfunction of many peripheral
  nerves throughout the body.
• In CIP, with biopsy, one sees that the patient
  develops both motor and sensory degeneration
  without inflammation. Dhand pp. 1033

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Risk factors for polyneuropathy

• Poor control of blood sugar levels in diabetes
  causes several forms of polyneuropathy,
  collectively referred to as diabetic neuropathy.
  Merck Manual
• Diphtheria toxins, autoimmune reaction, heavy
  metals such as lead and mercury and CO poisoning
  can all lead to polyneuropathy.
• The drugs include the anticonvulsant, Dilantin,
  some antibiotics (such as nitrofurantoin and
  sulfonamides), some chemotherapy drugs and some
  sedatives such as barbital. Merck Manual

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Risk factors for Critical illness polyneuropathy

• History of sepsis, trauma, burn followed by organ
  failure, septic encephalopathy. Dhand pp. 1033.
  
• in addition, according to the CDC, CIP is
  associated with a recent history of SIRV septic
  inflammatory response syndrome. CDC
  http//www.cdc.gov/nchs/data/icd9/icd501a.pdf

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S/S critical illness polyneuropathy

• On inspection
• Because cranial nerves are generally unaffected
  in CIP, the patients facial grimace and limb
  movement on painful stimulation may be strikingly
  different. CDC
• A muscle biopsy would show neuropathic changes.
  Dhand pp. 1034.

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S/S critical illness polyneuropathy

• He have a normal Creatine kinase. Dhand pp.
  1034.
• he would have a reduction in both motor sensory
  nerve conduction. Dhand pp. 1029.

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S/S critical illness polyneuropathy

• EMG results
• the EMG showed action potentials twice normal
  with increased fibers per motor unit and an
  increase in duration of the action potential.
  http//en.wikipedia.org/wiki/Amplitude

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Prolonged neuromuscular blockage

• Nondepolarizing neuromuscular blocking agents
  such as pancuronium generally have duration of
  action of a few hours, but a few patients may
  suffer persistant weakness that can prevent
  successful weaning from ventilatory support. This
  paralysis could last additional hours--- or even
  weeks. Dhand pp. 1037

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Prolonged neuromuscular blockage
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Prolonged neuromuscular blockage

• Prolonged neuromuscular blockage with
  nondepolarizing blocking agents results in
  metabolites.
• Prolonged neuromuscular blockade after the
  termination of long-term treatment with
  vecuronium is associated with metabolic acidosis,
  elevated plasma magnesium concentrations, female
  sex, and probably more important, the presence of
  renal failure, and high plasma concentrations of
  3-desacetylvecuronium. V Segredo

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Risk factors for Prolonged neuromuscular blockage

• Patients at increased risk seem to be those with
  
• hepatic dysfunction
• renal failure
• acidosis
• or hypermagnesemia Dhand pp. 1036

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Differential DX
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Differential DX

• Polyneuropathies such as Guillian Barre syndrome
  can be triggered by infection,
• while exacerbations of myasthenia gravis MG
  crisis can be triggered by stress, certain
  medications and illness.
• Spinal cord infarction is a complication of
  aortic surgery Dhand pp. 1026.
• myotonic dystrophy may have been undiagnosed

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Differential DX

• Guillian Barre.
• There are no antibodies in the serum of
  patients with critical illness polyneuropathy as
  would be seen with Guillian Barre.
  http//jnnp.bmj.com/cgi/content/extract/68/3/397

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Differential DX

• myasthenia gravis.
• Patients have increasing muscle weakness with
  repetitive motions
• they also antibodies against acetylcholine
  receptors
• tendency to have a degree of facial paralysis
  inability to protect the airway,
• a transient improvement when given cholinesterase
  inhibitors. Egans pp. 576

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Differential DX

• Spinal cord infarction
• Comes on suddenly and catostrophically with 80
  c/o severe pain
• http//www.emedicine.com/NEURO/topic348.htm

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Differential DX

• myotonic dystrophy
• Persons with myotonic dystrophy have increased
  sensitivities not only to paralytic agents, but
  to CNS depressants. Egans pp. 576

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Treatment?

• According to the CDC, there are no medications
  for these problems, rather we need to consider
  conservative management. CDC

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We need to stop killing black widow spiders with
a sledge hammer.
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May just tear up the house
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Conservative measures w/ steroids

• According to the American Heart Association 2005
  CPR guidelines, severe asthma needs to be treated
  with systemic steroids rather than topical
• but maybe we need more studies to be done with
  inhaled dosages so that the systemic side effects
  such as myopathy can be minimized?
• In these studies, how are these patients given
  inhaled steroids? mixed with Beta II or alone?
  SVN or MDI, DPI?
• Exactly what are the links between
  steroid-induced diabetes and neuropathy how much
  steroid is too much?

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Conservative measures w/ steroid TX

• could we use offline measurements for intubated
  patients?
• Research is on going on the question of using
  exhaled nitric oxide monitors to fine-tune the
  level of systemic steroids in the acute
  asthmatic. Phua pp. 857
• Offline measurement of FENO has been compared
  favorably with online modes
• One UK single-blind study over a period of 8
  months n 116 showed no clinically significant
  improvement in controlling patients steroid
  dosages by monitoring FENO http//ajrccm.atsjourna
  ls.org/cgi/content/abstract/176/3/231

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Conservative measures w/ Nondepolarizing
neuromuscular blockers

• Limit time of paralysis. Sedation vacations are
  used to decrease VAP by getting patients off
  mechanical ventilation sooner. Kress
• Maybe this same technique might be helpful with
  CIM prolonged neuromuscular blockage?

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Conservative measures w/ Beta II

• Never forget the Beta II agonists have as side
  effects
• increases both insulin and glucose levels, when
  combining high dosage Beta II and corticosteroids
  this could get serious
• Causes hypokalemia. According to the AHA, inhaled
  10-20 mg Albuterol over 15 will shift Potassium
  into the cell to treat both moderate severe
  hyperkalemia AHA 2005 CPR guidelines pp.
  121-122
• Compare this to the AHA recommendations regarding
  continuous Albuterol TX 2.5-5mg Q 20 minute x 3
  or 10-15 mg/hour

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Conservative measures w/ Beta II

• The AHA recommend these drugs as adjuncts to
  albuterol/IV steroid treatment
• A trial of ipratropium bromide as adjunct to
  albuterol, possibly more that one dose AHA
  pp.140
• IV Magnesium Sulfate
• Leukotriene antagonists by IV has been studied
  but the AHA wants more research

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Other bronchodilators can have neuromuscular side
effects

• According to the post-marketing experience with
  Singulair TM a few patients have reported
  paraesthesia hypoesthesiathese side effects
  have not been investigated yet. drug insert
• Cromolyn Na has peripheral neuritis as a rare
  side effect 1 in 100,000
• Magnesium by IV has respiratory failure due to
  skeletal muscle paralysis as a side effect

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references

• Neil MacIntyre Understanding Ventilator-Induced
  Diaphragmatic Dysfunction 
• http//www.medscape.com/viewarticle/514526
• Deem S. Intensive-Care-Unit-Acquired Muscle
  Weakness. Respiratory Care 2006 51(9) 1024-1041
• Dhand, U. Clinical Approach to the Weak patient
  in the Intensive Care Unit. Respiratory Care
  2006 51(9) 1024-1041
• Boitano, L.J. Management of Airway Clearance in
  Neuromuscular Disease Respiratory Care August
  2006, vol 51 (8) pp. 913-921.

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references

• Nutritional Assessment of patients with
  respiratory Disease Peters, J.A. Thomas-Peters,
  C.D., editors Wilkins Clinical Assessment in
  Respiratory Care 5th edition Elsevier-Mosby
• Medline Rhabdomyolysis http//www.nlm.nih.gov/med
  lineplus/ency/article/000473.htm
• E-medicine Hypokalemia David Garth, MD,
  http//www.emedicine.com/emerg/topic273.htm
• American College of Rheumatologyhttp//www.rheuma
  tology.org/public/factsheets/myopathies_new2.asp

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references

• Kress JP, Pohlman AS, O'Connor MF, Hall JB. Daily
  interruption of sedative infusions in critically
  ill patients undergoing mechanical ventilation.
  New England Journal of Medicine. May 18 2000342
  (20)1471-1477.
• Phua, GC MacIntyre NR, Inhaled Corticosteriods
  in COPD, Respiratory Care July 2007 , vol 52 7
• Critical illness polyneuropathy and myopathy
  http//www.aic.cuhk.edu.hk/web8/critical_illness_n
  europathy.htm
• CDC pamphlet on CIM and CIPhttp//www.cdc.gov/nchs
  /data/icd9/icd501a.pdf
• Merck Manual Polyneuritis http//www.merck.com/mm
  he/sec06/ch095/ch095h.html
• eMedicine Hypermagnesemia by Novello NA
  http//www.emedicine.com/EMERG/topic262.htm
•  

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references

• Medline Plus nerve conduction studies
  http//0-www.nlm.nih.gov.catalog.llu.edu/medlinepl
  us/ency/article/003927.htm
• AMERICAN THORACIC SOCIETYRecommendations for
  Standardized Procedures for the Online and
  Offline Measurement of Exhaled Lower Respiratory
  Nitric Oxide and Nasal Nitric Oxide in Adults and
  Children1999
• http//ajrccm.atsjournals.org/cgi/content/full/160
  /6/2104?ijkey43b2934ac6dfa8de010ee9b85d910dbfed79
  7135keytype2tf_ipsecsha
•  

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references

• V Segredo, JE Caldwell, et al. Persistent
  paralysis in critically ill patients after
  long-term administration of vecuronium. NEJ Vol
  327524-528 8 August 20, 1992 http//content.nejm
  .org/cgi/content/abstract/327/8/524?ijkey8e4db6ae
  a6531d7ea4f0d9c3eb1a90f706fb333fkeytype2tf_ipsec
  sha