Reduction of respiratory system resistance of rabbits with surfactant deficiency using a novel ultra thin walled endotracheal tube.
The ultra thin walled, two-stage endotracheal tube (UTW-TS-ETT) is very flexible, nonkinking, and has a widened extralaryngeal portion. The UTW-TS-ETT has a greater ID/OD (internal diameter/outer diameter) ratio than a comparable standard endotracheal tube (ST-ETT) because of its thinner wall: 0.2-0.25 mm in UTW-TS-ETT, compared to 0.55-0.8 mm in ST-ETT. The authors hypothesized that in an animal model of lung disease, significant reductions in respiratory system resistance (Rrs) of 30-40% would be achieved using the UTW-TS-ETT, compared to Rrs achieved with the comparable ST-ETT. This study compared the pulmonary mechanics of rabbits (N = 17, body weight 3.4-4.7 kg) before and after induction of surfactant deficiency, using either ST-ETT (OD 4.9 mm, ID 3.5 mm) or UTW-TS-ETT (OD 5.0 mm, ID 4.6 mm). Animals were sedated, paralyzed, and ventilated by an ETT placed through a tracheotomy incision. Surfactant deficiency was induced by lavaging the lungs with normal saline (10 ml/kg). Pulmonary mechanics were measured on identical ventilator settings for each ETT used at baseline and at 45 min after lavage. Compared to ST-ETT, UTW-TS-ETT reduced Rrs by 50.6 +/- 8.7% in normal lungs (significantly more than 40%; p < 0.01), and by 41.47 +/- 16.2% in surfactant deficient lungs (significantly more than 30%; p < 0.05). Tidal volume increased with UTW-TS-ETT in all animals but did not achieve statistical significance. The UTW-TS-ETT did not induce significant changes in respiratory system compliance, PaO2, PaCO2, or pH. It is concluded that UTW-TS-ETT significantly reduces Rrs in rabbits with either normal lungs or with surfactant deficient lungs. This novel ETT may be beneficial for ventilated patients with increased Rrs, by effecting a decrease in Rrs and thus reducing the work of breathing and improving ventilation efficiency.
Makhoul
I R
IR
Department of Neonatology, Rambam Medical Center, Haifa, Israel.
Kugelman
A
A
Bui
K C
KC
Berkeland
J E
JE
Saiki
K
K
Lew
C D
CD
Garg
M
M
D000818:Animals; D001672:Biocompatible Materials / Q000592:standards*; D002245:Carbon Dioxide / Q000378:metabolism; D007442:Intubation, Intratracheal / Q000592:standards*; D010101:Oxygen Consumption; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange; D011663:Pulmonary Surfactants / Q000172:deficiency*; D011817:Rabbits; D012119:Respiration / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000628:therapy; D012129:Respiratory Function Tests
D001672:Biocompatible Materials; D011663:Pulmonary Surfactants; D002245:Carbon Dioxide