Effect of closed endotracheal tube suction method, catheter size, and post-suction recruitment during high-frequency jet ventilation in an animal model.

Hepponstall, J Michele; Tingay, David G; Bhatia, Risha; Loughnan, Peter M; Copnell, Beverley

RATIONALE High-frequency jet ventilation (HFJV) is often used to treat infants with pathologies associated with gas trapping and abnormal lung mechanics, who are sensitive to the adverse effects of suction. OBJECTIVE This study aimed to investigate the effect of closed suction (CS), catheter size, and the use of active post-suction sighs on tracheal pressure (P(trach)), and global and regional end-expiratory lung volume (EELV) during HFJV. METHODS Six anaesthetized and muscle-relaxed adult rabbits were stabilized on HFJV. CS was performed using all permutations of three CS methods (Continual negative pressure, negative pressure applied during Withdrawal, and HFJV in Standby) and 6 French gauge (6 FG) and 8 French gauge (8 FG) catheter, randomly assigned. The sequence was repeated using post-suction sighs. P(trach), absolute (respiratory inductive plethysmography) and regional (electrical impedance tomography; expressed as percentage of vital capacity for the defined region of interest, %Z(VCroi) ) EELV were measured before, during and 60 sec post-suction. RESULTS CS methods exerted no difference on ΔP(trach), ΔEELV(RIP), or Δ%Z(VCroi) . 8FG catheter resulted in a mean (95%CI) 20.0 (17.9,22.2) cm H(2)O greater loss of P(trach) during suction compared to 6FG (Bonferroni post-test). Mean (± SD) ΔEELV(RIP) was -6(±3) and -2(±1) ml/kg with the 8 and 6 FG catheters (P < 0.0001; Bonferroni post-test). ΔEELV was 31.7 (21.1,42.4) %Z(VCroi) and 24.8 (10.9,38.7) %Z(VCroi) greater in the ventral and dorsal hemithoraces using the 8 FG. Only after 8 FG CS was post-suction recruitment required to restore EELV. CONCLUSIONS In this animal model receiving HFJV, ΔP(trach), ΔEELV, and need for post-suction recruitment during CS were most influenced by catheter size. Volume changes within the lung were uniform.