Biomaterial Database

Relationship between chronic hypercapnia and inspiratory-muscle weakness in myotonic dystrophy. 1997

P Bégin, and J Mathieu, and J Almirall, and A Grassino

Department of Medicine, University of Montréal, Québec, Canada.

We studied 134 patients with Steinert's myotonic dystrophy (MD) in order to determine the prevalence of chronic hypercapnia, the level of muscle weakness and forced expiratory volume at which hypercapnic respiratory failure is likely to occur, and how clinical assessment might help predict hypercapnic respiratory failure. Subjects were divided into five classes with a muscular disability rating scale (MDRS): 0 = no clinical impairment (n = 9), I = minimal signs of impairment (n = 11), II = distal weakness (n = 41), III = moderate proximal weakness (n = 62), and IV = nonambulatory (n = 11). The prevalence of hypercapnia (PaCO2 > or = 43 mm Hg) was found to be 0%, 27%, 29%, 45% and 55% for MDRS 0 to 4, respectively (p = 0.03). A multiple regression analysis limited to clinical data showed that daytime hypersomnolence was a significant cofactor with the MDRS (p = 0.01) in predicting PaCO2 (r = 0.40). Among respiratory parameters, FVC, respiratory muscle strength (RMS), and maximal inspiratory pressure against occluded airways (PImax) were found to be predictors of nearly equal strength, explaining 16%, 15%, and 14% of the PaCO2 variance, respectively. In multiple regression analysis, sex, daytime sleepiness, and the expected/observed FVC ratio for a given RMS were found to be significant cofactors with PImax in predicting PaCO2 (r = 0.51). It is concluded that respiratory insufficiency should be suspected in MD patients with proximal weakness or daytime sleepiness. The likelihood of hypercapnia also increases with volume restriction and respiratory muscle weakness. Our study suggests that the combination of inspiratory muscle weakness and loading plays a predominant role in the pathogenesis of chronic alveolar hypoventilation in MD patients. The occurrence of daytime hypersomnolence suggests that other factors, such as low central ventilatory drive or sleep apnea, might play an additional role.

UI	MeSH Term	Description	Entries
D006970	Disorders of Excessive Somnolence	Disorders characterized by hypersomnolence during normal waking hours that may impair cognitive functioning. Subtypes include primary hypersomnia disorders (e.g., IDIOPATHIC HYPERSOMNOLENCE; NARCOLEPSY; and KLEINE-LEVIN SYNDROME) and secondary hypersomnia disorders where excessive somnolence can be attributed to a known cause (e.g., drug affect, MENTAL DISORDERS, and SLEEP APNEA SYNDROME). (From J Neurol Sci 1998 Jan 8;153(2):192-202; Thorpy, Principles and Practice of Sleep Medicine, 2nd ed, p320)	Daytime Sleepiness,Daytime Somnolence,Excessive Daytime Sleepiness,Hypersomnia,Hypersomnolence,Primary Hypersomnia Disorders,Secondary Hypersomnia Disorders,DOES (Disorders of Excessive Somnolence),Excessive Somnolence Disorders,Hypersomnia, Recurrent,Hypersomnolence Disorders,Hypersomnolence Disorders, Primary,Hypersomnolence Disorders, Secondary,Primary Hypersomnolence Disorders,Secondary Hypersomnolence Disorders,DOESs (Disorders of Excessive Somnolence),Daytime Sleepiness, Excessive,Daytime Sleepinesses,Daytime Somnolences,Excessive Daytime Sleepinesses,Excessive Somnolence Disorder,Hypersomnia Disorder, Primary,Hypersomnia Disorder, Secondary,Hypersomnias,Hypersomnolence Disorder,Hypersomnolence Disorder, Primary,Hypersomnolence Disorder, Secondary,Primary Hypersomnia Disorder,Primary Hypersomnolence Disorder,Recurrent Hypersomnia,Recurrent Hypersomnias,Secondary Hypersomnia Disorder,Secondary Hypersomnolence Disorder,Sleepiness, Daytime,Sleepiness, Excessive Daytime,Somnolence Disorder, Excessive,Somnolence, Daytime
D009223	Myotonic Dystrophy	Neuromuscular disorder characterized by PROGRESSIVE MUSCULAR ATROPHY; MYOTONIA, and various multisystem atrophies. Mild INTELLECTUAL DISABILITY may also occur. Abnormal TRINUCLEOTIDE REPEAT EXPANSION in the 3' UNTRANSLATED REGIONS of DMPK PROTEIN gene is associated with Myotonic Dystrophy 1. DNA REPEAT EXPANSION of zinc finger protein-9 gene intron is associated with Myotonic Dystrophy 2.	Dystrophia Myotonica,Myotonic Dystrophy, Congenital,Myotonic Myopathy, Proximal,Steinert Disease,Congenital Myotonic Dystrophy,Dystrophia Myotonica 1,Dystrophia Myotonica 2,Myotonia Atrophica,Myotonia Dystrophica,Myotonic Dystrophy 1,Myotonic Dystrophy 2,PROMM (Proximal Myotonic Myopathy),Proximal Myotonic Myopathy,Ricker Syndrome,Steinert Myotonic Dystrophy,Steinert's Disease,Atrophica, Myotonia,Atrophicas, Myotonia,Congenital Myotonic Dystrophies,Disease, Steinert,Disease, Steinert's,Dystrophia Myotonica 2s,Dystrophia Myotonicas,Dystrophica, Myotonia,Dystrophicas, Myotonia,Dystrophies, Congenital Myotonic,Dystrophies, Myotonic,Dystrophy, Congenital Myotonic,Dystrophy, Myotonic,Dystrophy, Steinert Myotonic,Myopathies, Proximal Myotonic,Myopathy, Proximal Myotonic,Myotonia Atrophicas,Myotonia Dystrophicas,Myotonic Dystrophies,Myotonic Dystrophies, Congenital,Myotonic Dystrophy, Steinert,Myotonic Myopathies, Proximal,Myotonica, Dystrophia,Myotonicas, Dystrophia,PROMMs (Proximal Myotonic Myopathy),Proximal Myotonic Myopathies,Steinerts Disease,Syndrome, Ricker
D011446	Prospective Studies	Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.	Prospective Study,Studies, Prospective,Study, Prospective
D012132	Respiratory Muscles	These include the muscles of the DIAPHRAGM and the INTERCOSTAL MUSCLES.	Ventilatory Muscles,Respiratory Muscle,Muscle, Respiratory,Muscle, Ventilatory,Muscles, Respiratory,Muscles, Ventilatory,Ventilatory Muscle
D002908	Chronic Disease	Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care (Dictionary of Health Services Management, 2d ed). For epidemiological studies chronic disease often includes HEART DISEASES; STROKE; CANCER; and diabetes (DIABETES MELLITUS, TYPE 2).	Chronic Condition,Chronic Illness,Chronically Ill,Chronic Conditions,Chronic Diseases,Chronic Illnesses,Condition, Chronic,Disease, Chronic,Illness, Chronic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006935	Hypercapnia	A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.
D012720	Severity of Illness Index	Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.	Illness Index Severities,Illness Index Severity
D014797	Vital Capacity	The volume of air that is exhaled by a maximal expiration following a maximal inspiration.	Forced Vital Capacity,Capacities, Forced Vital,Capacities, Vital,Capacity, Forced Vital,Capacity, Vital,Forced Vital Capacities,Vital Capacities,Vital Capacities, Forced,Vital Capacity, Forced
D016014	Linear Models	Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.	Linear Regression,Log-Linear Models,Models, Linear,Linear Model,Linear Regressions,Log Linear Models,Log-Linear Model,Model, Linear,Model, Log-Linear,Models, Log-Linear,Regression, Linear,Regressions, Linear