Ventilator-Assisted Living©

Winter 2002, Vol. 16, No. 4

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Managing Noninvasive Ventilation: A Portuguese Experience

João Carlos Winck, MD, and Miguel Gonçalves, PhT, Rehabilitation and Lung Function Unit, Pneumology Department, Hospital São João, Faculdade de Medicina-Porto, Portugal

Noninvasive ventilation (NIV) is becoming an evidence-based management approach to patients with acute or chronic respiratory failure. The past decade has seen an increase in the use of NIV, largely due to the development of nasal ventilation for greater convenience, comfort, safety, and less cost than invasive ventilation.

Photo of Miguel GoncalvesS. João Hospital is a university institution, the largest hospital in the city of Porto, in northern Portugal, drawing from an area of approximately 3 million inhabitants. In 2001, our department followed 43 patients using NIV at home. The Portuguese government pays for bilevel positive pressure units; volume ventilators are hard to obtain. Unfortunately home care is not organized and is mainly operated by private equipment providers. Caregivers are family members, with primary physicians and nurses visiting at home.

We manage chronic respiratory failure (CRF) patients in the Sleep Laboratory, part of the pulmonary function unit of the Pneumology Department, performing a wide variety of pulmonary function tests, arterial blood gas analysis, and sleep studies. Most of the patients evaluated in this unit have obstructive sleep apnea (OSA) syndrome, obesity hypoventilation syndrome, or CRF due to obstructive or restrictive syndromes. Our sleep service includes two beds for full polysomnography and up to four for simplified sleep studies. Multiple sleep latency tests are also performed regularly.

COPD patients with CRF are evaluated for long-term oxygen therapy. In case of symptomatic hypercapnia (high CO2) with nocturnal hypoventilation and recurrent exacerbations with hospital admissions, a trial of NIV may be started.

The individuals with CRF and restrictive syndromes are mostly people with neuromuscular disorders (ALS, myotonic dystrophy, Duchenne and other muscular dystrophies). Our four-step management approach includes evaluation of respiratory involvement, adaptation to NIV, follow-up, and respiratory muscle aids. Each step is done on an outpatient basis.

In evaluating respiratory involvement, we conduct pulmonary function tests (including inspiratory and expiratory muscle strength), home pulse oximetry, and arterial blood gas analysis. We also evaluate unassisted and assisted peak cough expiratory flows and maximum insufflation capacity. A formal sleep study may be also performed, especially if sleep apnea is suspected.

In initiating NIV, we connect the patient to a ventilator with a display (BiPAP® Vision, www.respironics.com), monitor leaks and titrate ventilatory parameters using plethysmography (Respitrace Plus, www.viasyscriticalcare.com), and pulse oximetry for SpO2 and transcutaneous CO2. Based on these physiological responses and patient tolerance, we choose the proper settings and the most efficient and comfortable interface. Finally we teach how to manage the ventilator and interface at home. A second pulse oximetry is conducted to ensure adequate settings.

After analysing the results of the first step, we evaluate the patient’s adaptation to NIV and compliance. Difficulties with managing NIV at home are discussed with patient and caregiver: the interface is one of the primary concerns. Again based on physiologic data, a decision on changing settings, ventilatory mode, or interface is made, in order to improve comfort and success of home NIV.

Neuromuscular patients have very low vital capacity and their thoracic cages are very stiff. Mobilization of the lungs to prevent chest wall contractures and lung restriction is achieved by providing regular deep volumes of air (insufflations) or deep breaths with NIV. We teach the patient to “air stack” with a manual resuscitator and to practice several times at home. The objectives are: increasing their cough flows and maximum insufflation capacity, maintaining or improving lung elasticity, and preventing or eliminating atelectasis (incomplete expansion of the lungs). We also teach our patients to “air stack” with glossopharyngeal or frog breathing.

photo of patient being assisted with CoughAssistMost of these patients have inefficient cough due to muscle weakness, and we teach the family manually assisted coughing techniques. If the patient cannot achieve good cough flows with manual techniques, the next approach uses mechanically assisted cough (CoughAssist™) to help clear airway secretions.

The CoughAssist is not commercially available in our country yet, but we are using one unit in our department in a clinical study of the efficacy of the device. Our preliminary results confirm good tolerance and physiologic improvement in patients with either restrictive or obstructive disorders, and the usefulness of the CoughAssist as a complement to NIV.

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