Noninvasive respiratory muscle aids during PEG placement in ALS patients with severe ventilatory impairment
Introduction
Around 80% of amyotrophic lateral sclerosis (ALS) patients, independent of the site of onset, develop progressive bulbar dysfunction (BD) [1]. As a consequence, a progressive swallowing impairment appears, causing malnutrition, weight loss, and dehydration. These problems can also be accompanied by recurrent episodes of choking, aspiration, respiratory infections, and pneumonia [1]. As malnutrition is an independent prognostic factor for survival in ALS patients [2], and respiratory problems due to aspiration decrease effectiveness of noninvasive respiratory muscle aids, it is important to manage dysphagia [3].
Initial control of dysphagia in ALS is based on strategies to maintain nutritional intake by altering food consistency [4]. However, as BD progresses and these measures become ineffective, enteral nutrition delivered via percutaneous endoscopic gastrostomy (PEG) permits adequate feeding [4]. This feeding method stabilizes body weight and is probably effective in prolonging survival in ALS [5].
When this study started, international guidelines argued that the risks of respiratory complications related to the procedure increased when FVC was lower than 50% of predicted [6], and they recommended PEG placement before this moment [7]. However, these recommendations were based on studies that were methodologically deficient, in which, moreover, pulmonologists did not participate in the prevention and management of potential respiratory problems. Recently, when such guidelines were up-dated [4], a specific time for PEG placement was not recommended, although the existence of complications was stressed when FVC < 50%. Guidelines established by endoscopists do not mention the lowering of FVC as an absolute or relative contraindication of PEG placement [8].
In view of the potentially positive effect of noninvasive mechanical ventilation (NIV) to prevent and manage respiratory problems in ALS patients when respiratory muscles become weak [9], NIV has been proposed as a respiratory muscle support during PEG placement in order to reduce the related respiratory complications in those patients with FVC lower than 50% [10], [11]. At present, evidence of the usefulness of NIV for this purpose originates from a limited body of data, but the available results could make it possible to assume that, if NIV can be provided, the choice of the time of PEG placement can be decided in clinical practice in accordance with the seriousness of the patient's swallowing impairment and not necessarily on the fall in FVC. Based on this assumption, the aim of this study was to assess the efficacy of noninvasive respiratory muscle aids, NIV and mechanically assisted cough (MAC), to allow successful PEG placement in a cohort of ALS patients who already had severe ventilatory muscle impairment (SVMI) at the time at which PEG placement was decided.
Section snippets
Material and methods
This prospective study was performed between January 2005 and December 2009 at two university hospitals, and included all ALS patients diagnosed according to the revised El Escorial criteria [12] who, at the time of needing a PEG due to impaired oral food intake or progressive weight loss (> 10%), had a FVC lower than 50% of the predicted value or who used home NIV [4], [13]. All the patients had received clear information about PEG (its usefulness, placement procedure, and maintenance measures)
Pulmonary function assessment
Pulmonary function assessments were made prior to PEG placement. Spirometry was assessed with a pneumotachograph spirometer (MS 2000; Schatzman; Madrid, Spain) in accordance with the European Respiratory Society's guidelines [14] as described in previous studies [15]. FVC was measured both in sitting and supine positions.
Maximum inspiratory pressure (PImax) and maximum expiratory pressure (PEmax) were measured (Electrometer 78.905ª; Hewlett-Packard; Andover, MA, USA) according to the Black and
NIV-PEG protocol
Patients were admitted to hospital 24 h before the procedure, and from then on followed a protocol-based management [19].
A trained pulmonologist provided respiratory care measures. Before the patient was transferred to the endoscopy unit, MAC was applied with an in-exsufflation device (Cough-Assist™, Philips-Respironics International Inc., Murrysville, Pa, USA) through an oronasal mask (Martin Vecino, Madrid, Spain); 6–8 cycles (insufflation pressure + 40 cm H2O, exsufflation pressure −40 cm H20,
Results
All the patients chose swallowing impairment, and not the state of their respiratory muscles, as the point at which PEG was to be performed, and they all agreed to participate in this study.
PEG under NIV and MAC was indicated for 30 patients with SVMI during this study. Fourteen of them had bulbar onset (46.7%), and at that time all of them had severe BD. Data on demographics, respiratory function, and cough capacity assessment are shown in Table 1. The mean loss of BMI during the previous 6
Discussion
If explicit or consistent guidelines are not available, the decision to place a PEG tube should focus mainly on the patient's inability to ingest food or water by mouth [21]. However, the fact that respiratory muscle weakness in ALS may appear before severe dysphagia has led some authors to consider that the evolution of FVC outweighs dysphagia when deciding on the timing for PEG. In contrast to this current opinion, this study supports the feasibility and safety of PEG timed by swallowing
Conflict of interest statement
JS, ES, ECh, EG, JNS and JM have no financial relationship with any commercial entity that has an interest in the subject of this manuscript. P.B. is supported by a grant from the Fundación para la Investigación del Hospital Clínico sponsored by Vital Aire Inc.
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