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chronic hypercapneic respiratory failure
Etiology:
1) COPD
2) neuromuscular disease
a) myasthenia gravis
b) amyotrophic lateral sclerosis (ALS)
c) multiple sclerosis
3) chest wall skeletal disorders - kyphoscoliosis
4) obesity
Pathology:
- decreased ventilatory drive
- patients with respiratory muscle weakness, obesity, & disorders of ventilatory control, 1st hypoventilate during rapid-eye-movement sleep
Clinical manifestations:
1) nighttime awakenings with dyspnea
2) orthopnea
2) increasing fatigue or daytime sleepiness
3) may be symmetric muscle weakness
4) lungs may be clear to auscultation
Laboratory:
1) arterial blood gas
a) increased pCO2
b) respiratory acidosis with metabolic compensation
2) chem7
a) anion gap normal
b) increased serum bicarbonate compensatory to hypercapnia
Special laboratory:
1) pulmonary function testing
a) maximum inspiratory effort & maximum expiratory effort
- if normal or near normal, suspect disorder of ventilatory control
b) vital capacity with changes in position
c) helpful for assessing role of neuromuscular weakness [1]
2) polysomnography
a) nocturnal hypoventilation suspected
b) daytime sleepiness, nocturnal awakening, morning headaches
Management:
- COPD patients benefit from CPAP
- most patients benefit from BiPap (exception is COPD)
- nocturnal non-invasive positive pressure ventilation is the usual initial method of respiratory assistance [1]
- improves quality of life
- delays progression of respiratory failure in patients with neuromuscular disease [1,2]
General
hypercapneic respiratory failure
chronic respiratory failure
chronic lung disease
References
- Medical Knowledge Self Assessment Program (MKSAP) 14, 17, 19.
American College of Physicians, Philadelphia 2006, 2015, 2022
- Ambrosino N, Carpene N, Gherardi M.
Chronic respiratory care for neuromuscular diseases in adults.
Eur Respir J. 2009 Aug;34(2):444-51
PMID: 19648521