A TIMED REEXPANSION INSPIRATORY MANEUVER (TRIM) FOR TREATING OXYHEMOGLOBIN DESATURATION IN CHILDREN FOLLOWING A PERIOD OF APNEA - STUDIES IN AN ANIMAL-MODEL

Our clinical experience has shown that the use of a constant distendin g airway pressure of 30 cm water for 10 s, termed a timed reexpansion inspiratory manoeuvre (TRZM), is often successful in correcting oxyhae moglobin desaturation in anaesthetized children. The aim of this study was to assess the efficacy of TRIM in lambs. Following a standard rel axant anaesthetic, ventilation was stopped and oxyhaemoglobin saturati on allowed to fall to 70% and the time taken to return to baseline was compared between three groups. The median time was 42.5 s when ventil ation was restarted with 33% oxygen in nitrous oxide (33% group), 30 s when ventilation was restarted with 100% oxygen (100% group) and 22.5 s with a TRIM before restarting ventilation with 33% oxygen in nitrou s oxide (TRIM group). The correction of desaturation was more rapid in the TRIM group compared with the 33% group (P<0.004) and the 100% gro up (P<0.003). Oxyhaemoglobin desaturation due to apnoea in anaesthetiz ed lambs is more effectively treated with a TRIM than by increasing th e inspired oxygen fraction.