[Physiological parameters of breathing and the impact of non-invasive ventilation (NIV) on patients with amyotrophic lateral sclerosis (ALS)]

Abstract

Background: Amyotrophic lateral sclerosis (ALS), as a consequence of the progressive failure of respiratory muscles, often causes chronic ventilatory failure (CVF), indicated by hypercapnia. This study analyses the physiological parameters of breathing in patients with ALS over time and the variables which influence survival time.

Methods: In this observational study we analysed the data of physiological parameters (respiratory function, blood gas levels and breathing during sleep), as well as survival rate (according to Kaplan-Meier) of all 85 ALS patients who stayed in our hospital during the period of 1st January 2003 until 31st December 2007. After ALS had been diagnosed, all patients ran through standardised pneumological diagnostics during the observation period, this procedure was repeated every 3-6 months. If hypercapnia (carbon dioxide tension pCO(2) > 45 mm Hg) was detected, non-invasive ventilation (NIV) was indicated and offered to the respective patients.

Results: In the course of the observation, the parameters of respiratory function IVC (inspiratory vital capacity) and FEV1 (forced expiratory volume after 1 second) have shown a significant reduction by 14-15% per year. Half of the patients died within 3.1 years after ALS had been diagnosed. IVC and FEV1 had no impact on the survival time. In contrast, pCO(2) correlates negatively with the survival time. The period between diagnosis of ALS and manifestation of hypercapnia is about 1.9 +/- 2.4 years. In spite of a clear indication, some of the patients did not comply with NIV or did not accept it (19 patients, 22%). Twenty-eight patients (33%) started NIV with a good compliance. The survival rate of patients with NIV was 1.27 years on average--after the initial measurement of hypercapnia. The survival time of hypercapnic patients without NIV was only 0.12 years.

Conclusions: Hypercapnia has a significant impact on the prognosis for ALS patients. In the case of CVF (hypercapnia), the survival time of ALS patients is significantly reduced. NIV is able to significantly increase the survival time of ALS patients with hypercapnia.

Georg Thieme Verlag KG Stuttgart-New York.