Effects of flow rate on delivery of bubble continuous positive airway pressure in an in vitro model.
BACKGROUND
There has been concern over the effect of vigorous bubbling on the delivery pressure during the operation of the bubble nasal continuous positive airway pressure (CPAP) system. We investigated the relationship between intra-tubing pressure changes and flow rates in a closed bubble CPAP system in vitro.


METHODS
Using an experimental (in vitro) model, the distal connecting tube of the CPAP system was immersed under the water seal to a depth of 5 cm. Sixteen different flow rates, ranging from 2 L/min to 20 L/min, were tested. The procedure was repeated 10 times at each flow rate, and the intra-tubing pressure was recorded.


RESULTS
The intra-tubing pressure within the model increased as the air flow rates were adjusted from 2 L/min to 20 L/min. The relationship was represented by the following equation, pressure (cmH(2)O) = 5.37 + 0.15 x flow rate (L/min) (R(2) = 0.826, p < 0.001).


CONCLUSIONS
These results demonstrated that the intra-tubing pressure in a bubble CPAP system was highly correlated with flow rate in vitro.
Ho
Tsyr-Yuh
TY
Division of Pediatrics, Zuoying Armed Forces General Hospital, Kaohsiung, Taiwan. Electronic address: treeho@yahoo.com.tw.
Ou
Shan-Fu
SF
Division of Pediatrics, Zuoying Armed Forces General Hospital, Kaohsiung, Taiwan.
Huang
Shih-Hui
SH
Department of Nursing, Fooying University, Kaohsiung County, Taiwan.
Lee
Chi-Ning
CN
Division of Pediatrics, Zuoying Armed Forces General Hospital, Kaohsiung, Taiwan.
Ger
Luo-Ping
LP
Department of Pediatrics and Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, National Yang-Ming University, Taipei, Taiwan.
Hsieh
Kai-Sheng
KS
Department of Pediatrics and Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, National Yang-Ming University, Taipei, Taiwan.
Cheng
Hui-Ying
HY
Department of Nursing, Zuoying Armed Forces General Hospital, Kaohsiung, Taiwan.
Lee
Wei Yang
WY
Department of Pediatrics, Kaohsiung Municipal United Hospital, Kaohsiung, Taiwan.
Weng
Ken-Pen
KP
Division of Pediatrics, Zuoying Armed Forces General Hospital, Kaohsiung, Taiwan; Department of Nursing, Fooying University, Kaohsiung County, Taiwan; Department of Pediatrics and Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, National Yang-Ming University, Taipei, Taiwan; Yuh-Ing Junior College of Health Care and Management, Kaohsiung, Taiwan. Electronic address: kenpenweng@yahoo.com.tw.
D000399:Air Pressure; D000403:Airway Resistance / Q000502:physiology*; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007440:Intubation / Q000295:instrumentation*; D008954:Models, Biological; D012127:Respiratory Distress Syndrome, Newborn / Q000628:therapy*; D012212:Rheology