RT Journal Article
SR Electronic
T1 Different Tracheotomy Tube Diameters Influence Diaphragmatic Effort and Indices of Weanability in Difficult to Wean Patients
JF Respiratory Care
FD American Association for Respiratory Care
SP 2012
OP 2018
DO 10.4187/respcare.01747
VO 57
IS 12
A1 Ilaria Valentini
A1 Eva Tonveronachi
A1 Cesare Gregoretti
A1 Chiara Mega
A1 Luca Fasano
A1 Lara Pisani
A1 Stefano Nava
YR 2012
UL http://rc.rcjournal.com/content/57/12/2012.abstract
AB OBJECTIVE: To determine the effects of different tracheotomy tube sizes on diaphragm effort and weanability indices. METHODS: Ten tracheotomized and difficult to wean subjects were randomized to 2 T-piece trials, with different tracheotomy tube diameters: inner diameters 8 mm and 6.5 mm. Diaphragm pressure-time product per min. (PTPdi/min), lung compliance and resistance (CL and RL), breathing pattern, tension-time index of the diaphragm (TTdi), and the ratio of breathing frequency to tidal volume (f/VT) were recorded. In an in vitro model, the flow-pressure relationship was measured using the 2 tracheotomy tubes and 2 endotracheal tubes of the same diameter. RESULTS: The use of a smaller diameter resulted in an increase of PTPdi (337.63 ± 194.35 cm H2O · s/min vs 263.28 ± 156.23 cm H2O · s/min for 6.5 mm and 8 mm, respectively, P = .004) and RL (16.74 ± 8.10 cm H2O · s/min vs 11.72 ± 7.88 cm H2O · s/min, respectively, P = .008). Both weanability indices were also significantly higher using the smaller tube: f/VT 93.32 ± 20.91 vs 77.06 ± 19.26 for 6.5 mm and 8 mm, respectively, P < .02; TTdi 0.09 ± 0.052 vs 0.08 ± 0.04, respectively, P < .02. In vitro measurements confirmed that the resistances were higher with the smaller diameter and similar between the tracheotomy tubes and the endotracheal tubes of the same diameters. CONCLUSIONS: In tracheotomized difficult to wean subjects the decrease of the tracheotomy tube size was associated with an increased PTPdi, f/VT, and TTdi, that were otherwise normal, using a higher diameter. The in vitro study showed that the resistances increased similarly for tracheotomy tube and endotracheal tube, decreasing the diameter and increasing the flows.