Special Communications

Malnutrition and the Respiratory System

La dénutrition est fréquente au cours de l'insuffisance respiratoire chronique (IRC) évoluée. Elle est corrélée à un mauvais pronostic de survie. Sa physiopathologie repose sur une inégalité entre des besoins en énergie accrus et des apports alimentaires insuffisants. Trois types d'IRC sont abordés dans cette mise au point : la bronchopneumopathie chronique obstructive (BPCO), l'insuffisance respiratoire secondaire à la sclérose latérale amyotrophique (SLA), et celle liée à la mucoviscidose. Dans la BPCO, il est noté une augmentation des besoins énergétiques en raison de l'augmentation du travail respiratoire et des phénomènes inflammatoires sous la dépendance de cytokines pro-inflammatoires. Les compléments oraux et parfois la nutrition entérale peuvent être efficaces. Cependant les patients ne sont pas tous répondeurs, car la cachexie peut-être considérée comme une adaptation métabolique à l'hypoxie chronique. Dans la SLA, la dénutrition répond essentiellement à une insuffisance alimentaire en raison des troubles de déglutition. La nutrition entérale par sonde de gastrostomie est un traitement logique et doit être envisagée avec le patient. Dans la mucoviscidose, il existe très précocement des troubles de l'absorption digestive en rapport avec l'atteinte pancréatique. Le suivi nutritionnel s'impose dès le diagnostic, des suppléments en vitamines liposolubles et en extraits pancréatiques sont prescrits pour prévenir les carences. S'il est noté un arrêt de croissance chez l'enfant ou une perte de poids malgré les cures d'antibiotiques, la nutrition entérale après pose d'une gastrostomie percutanée est un traitement efficace.

Denutrition is common in end-stage respiratory insufficiency. It is correlated with a poor prognosis. It is due to an unbalance between increased energy demand and decreased oral supply. Pathophysiology of denutrition differs according to aetiology of chronic respiratory insufficiency. In patients with chronic obstructive pulmonary disease, it is well accepted that the high cost of work of breathing is the main explanation of the increased energy expenditure. In such situations, these patients do not eat enough nutrients and hence, may be considered for oral supplementation or enteral nutrition. However, some of them do not respond to this treatment, because cachexia may be the expression of the metabolic adaptation to chronic hypoxia. In other diseases, such as neurological disorders where difficulties of swallowing are involved, enteral nutrition via a gastrostomy is recommended. This support is also efficient in cystic fibrosis in which the intestinal absorption is impaired, mostly as a consequence of pancreatic insufficiency.

Mechanical ventilation (MV) in chronic situations is commonly used, either delivered invasively or by means of non-invasive interfaces, to control hypoventilation in patients with chest wall, neuromuscular or obstructive lung diseases (either in adulthood or childhood). The global prevalence of ventilator-assisted individuals (VAI) in Europe ranges from 2 to 30 per 100 000 population according to different countries.

Nutrition is a common problem to face with in patients with chronic respiratory diseases: nonetheless, it is a key component in the long-term management of underweight COPD patients whose muscular disfunction may rapidly turn to peripheral muscle waste. Since long-term mechanical ventilation (LTMV) is usually prescribed in end-stage respiratory diseases with poor nutritional status, nutrition and dietary intake related problems need to be carefully assessed and corrected in these patients.

This paper aims to review the most recent innovations in the field of nutritional status and food intake-related problems of VAI (both in adulthood and in childhood).

Accurate determination of energy expenditure is essential in patients receiving nutritional support to meet metabolic needs. The purpose of this study was to assess and compare the energy expenditure as measured by indirect calorimetry (MEE) and estimated by 5 equations in the mechanically ventilated critically ill patients. Forty-six patients were divided into either enteral nutrition (EN) (n=l2), total parenteral nutrition (TPN) (n=16) or combined (EN plus TPN) (n=l8) groups. Patients' energy expenditure was measured by indirect calorimetry on two occasions. Anthropometric and biochemical measurements, energy expenditure and medical status (APACHE II score) were also assessed in the intensive care unit (ICU) of Taichung Veteran General hospital. No significant difference was found in the MEE among the 3 groups. The type of nutritional support did not affect MEE. Energy expenditure calculated by using Harris– Benedict, Kleiber and Liu equations times the estimated stress factor did not significantly different than the values of MEE in all groups. There were significant correlations (P<0.01) between MEE and patients' sex (r=−0.499), age (r=−0.402), height (r=0.533), knee height (r=0.431), current body weight (r=0.379), usual body weight (r=0.407), ideal body weight (r=0.466) and urinary urea nitrogen (r=0.383) in the pooled group. Results demonstrated that energy expenditure could be estimated in most critically ill patients by using Harris–Benedict, Kleiber and Liu equations if the estimated stress factor is in the reasonable value.