Title: TSRC 37th Annual Convention Critical illness Myopathy & Critical illness Polyneuropathy
1TSRC 37th Annual ConventionCritical illness
Myopathy Critical illness Polyneuropathy
- By Elizabeth Kelley Buzbee AAS, RRT, NPS
- Lone Star System- Kingwood formerly known as
Kingwood College -
2Failure 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
3(No Transcript)
4Other 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
5The 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
6Occurrence 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
7Critical illness myopathy
8Critical 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
9Risk 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
10S/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.
11S/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
12S/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
13S/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
14S/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
15S/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
16S/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
17Critical illness polyneuropathy
18Critical 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
19Risk 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
20Risk 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
21S/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.
22S/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.
23S/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
24Prolonged 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
25Prolonged neuromuscular blockage
26Prolonged 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
27Risk factors for Prolonged neuromuscular blockage
- Patients at increased risk seem to be those with
- hepatic dysfunction
- renal failure
- acidosis
- or hypermagnesemia Dhand pp. 1036
28Differential DX
29Differential 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
30Differential 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
31Differential 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
32Differential DX
- Spinal cord infarction
- Comes on suddenly and catostrophically with 80
c/o severe pain - http//www.emedicine.com/NEURO/topic348.htm
33Differential DX
- myotonic dystrophy
- Persons with myotonic dystrophy have increased
sensitivities not only to paralytic agents, but
to CNS depressants. Egans pp. 576
34Treatment?
- According to the CDC, there are no medications
for these problems, rather we need to consider
conservative management. CDC
35We need to stop killing black widow spiders with
a sledge hammer.
36May just tear up the house
37Conservative 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?
38Conservative 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
39Conservative 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?
40Conservative 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
41Conservative 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
42Other 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
43references
- 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.
44references
- 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
45references
- 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 -
46references
- 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 -
47references
- 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