neuromuscular weakness Flashcards
NM weakness background
ICU Acquired Muscle Weakness ICUAW is a clinical syndrome of generalised muscle weakness that develops while a patient is critically ill, and for which there is no alternate explanation other than the critical illness itself (Hermans and Van den Bergh 2015).
ICUAW can be evoked either by critical illness polyneuropathy (CIP), by critical illness myopathy (CIM), or by both.
ICU-AW is detected in 30 to 50% of patients and the incidence is even higher (up to 67%) in critically ill patients with sepsis. (Piva et al. 2019)
Nationally, there was a mortality rate of 14% in patients in critical care and a further 7% died after leaving ICU before leaving acute hospital. Thus, 79% of the critically ill patients admitted to ICU or HDU survived to leave hospital. (Irish ICU Audit 2018
risk factors
for ICU acquired weakness
sepsis increase time of mechanical ventilation women higher BMI risk of anorexia for patients in ICU
diagnosis
The diagnosis of ICUAW requires a critical illness, or an illness of a very high severity with prolonged organ support, that is usually associated with a period of protracted immobilization.
Key clinical signs: presence of normal cognition, sparing of the cranial nerves, and the presence of symmetrical flaccid weakness.
Clinically detectable muscle weakness has been defined as ≤48 of the MRC sum score (60) (in the assessment of muscle strength in 3 muscle groups in the upper and lower limbs). Or a mean score of 4 in all testable muscle groups.
has to be critically ill to suspect icu acquired weakness
pathophysiology
Decreased muscle protein synthesis
Increased muscle catabolism
Decreased muscle mass with decreased force generation
Accompanied by axonal nerve degeneration.
Therefore ICUAW encompasses both critical illness polyneuropathy and myopathy
muscles need to be active to not lose strength
outcome measures
CPAX (Chelsea critical care physical assessment)
PFIT (Physical Function in ICU test)
FSS-ICU (Functional status score)
IMS (ICU mobility scale)
SPPB (short physical performance battery)
Handgrip dynamometry can also be used (this has been shown to be predictive of hospital mortality)
treatment
traffic light system
green - low risk of adverse effects
proceed as usual according to each ICUs protocols and procedures
yellow - potential risk and consequences of adverse event are higher than green
but may be outweighed by potential benefits of mobilisation
gradually and cautiously mobilise
red
potential risk of an adverse event
active mobilisation should not occur unless specifically authorised by the treating ICU specialist in consultation with senior PT and Senior N/S
Richmond agitation - sedation scale
(-5 - +4)
+4 combative
0 - alert and calm
-5 no response to voice or physical stimulation
early mobilisation in ICU
The reported benefits of early mobilization:
reduced ICU-acquired weakness,
improved functional recovery within hospital,
reduced hospital length of stay.
Limitations in the research??
prognosis
Reduced health related quality of life
Associated with increased post ICU mortality
Associated with reduced physical functioning
Additional research required
respiratory muscle weakness
Neuromuscular diseases (NMD) are a group of rare heterogeneous disorders that affect the function of peripheral nervous system components and may be accompanied by respiratory muscle weakness.
A common cause of morbidity and mortality in neuromuscular disease, substantially adding to the burden of the disease
Boentart et al. 2017
Respiratory impairment following spinal cord injury (SCI) is more severe in high cervical injuries, and is characterised by low lung volumes and a weak cough secondary to respiratory muscle weakness
Respiratory complications remain the most common cause of mortality following SCI
The respiratory muscles are frequently neglected in the rehabilitation approach of ICU AW. (Bissett et al.2020)
Respiratory muscle weakness, defined as the persistent incapacity of respiratory muscles to perform their mechanical functions or to generate sufficient pressure (Oliveira et al. 2018).
Inability to take a deep breath, to sigh, impaired cough, impaired secretion clearance, increased airway resistance….leading to risk of persistence infections.
respiratory muscle training
- treatment
Respiratory muscle training-training for strength and endurance.
Abdominal binder-fixing of the abdomen to allow the diaphragm to work more effectively
Non invasive ventilation
Assisted cough-vigorous pressure to left and right rib cage as patient starts to cough
Suction
Cough Assist (Mechanical insufflation-exsufflation): This procedure is started by applying positive pressure to the airway (insufflation) using a mechanical device to immediately afterwards transform this positive pressure into negative pressure (exsufflation).
