<qa>  What was the first validation study that showed that the adaptive servo ventilation therapy was effective?Earlier studies proved the adaptive servo ventilation to be an effective therapy for patients with central sleep-apnea and Cheyne-Stokes-respiration respectively. Teschler 2001 Teschlers study showed that the adaptive servo ventilation therapy with a reduction of central sleep apnea down to 10hours succeeded. With the SOMNOvent CR a new therapy-algorithm has been developed for the adaptive servo ventilation in patients with obstructive sleep apnea and Cheyne-Stokes-respiration with underlying heart disease. In the first validation study this therapy was very effective and presented only few adverse effects in the patients. Galetke 2007 