| Definition Apnea is defined as cessation of breathing with duration of 20 seconds or longer or any respiratory pause accompanied by bradycardia (i.e. heart rate <100 beats/min) and/or cyanosis. It is a common event occurred in the preterm infants. The are three typesof apnea: 1. Central apnea is defined as failure of both respiratory effort and air movement(air flow and chest wall movement cease simultaneously). See figure 1. (Central apnea of 23 seconds. Note desaturation and bradycardia accompanying apnea. There is a small amount of cardiogenic artifact in the impedance channel.)
2. Obstructive apnea is defined by active effort witth partial or complete blockage ofair movement (airflow ceases although chest wall movements continue throughout the apnea). See figure 2. (Repeated prolonged obstructive apnea with desaturation. Note total absence of nasal air flow with regular chest wall movement.)
3. Mixed apnea refers to that apnea in which, initially, there is a central eventfollowed by an obstruction component (chest wall movements occur intermittent during apnea). See figure 3. (Prolonged mixed apnea. Episode begins with a central apnea and becomes obstructive later. Bradycardia and desaturation accompany apnea.)
[Figures are copied from textbook "Intensive Care of the Fetus and Newborn", Spitzer AR. (ed).,Mosby, St. Louis, 1996; p472-473] It is thought that 40 per cent of the apneic spells are central, 10 per centare obstructive, and 50 per cent are mixed. (Martin RJ et al. J. Pediatr 1986; 109: 7333-741). |
