Premium
Distribution of Expiratory Gas and Rebreathing in a T‐piece Modification Combined with a PEEP Valve
Author(s) -
HartmannAndersen F.,
Andersen P. K.,
Olsen J. E.,
Jakubaszko J.
Publication year - 1984
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1984.tb02143.x
Subject(s) - medicine , positive end expiratory pressure , fresh gas flow , anesthesia , mechanical ventilation , ventilation (architecture) , weaning , sevoflurane , mechanical engineering , engineering
T‐piece modifications with PEEP valves are often used in weaning from mechanical ventilation or for intubated patients not requiring ventilatory support. Distribution of expiratory gas and the extent of rebreathing in a T‐piece modified with an inspiratory reservoir (ICR) and with a PEEP valve were studied in a model with various fresh gas flows (FGF), tidal volumes and frequencies at three valve settings: 0 cmH 2 O (ZEEP) and PEEP of 5 and 10 cmH 2 O (0.490–0.981 kPa). Two types of distribution of expiratory gas were delineated: type one with expiratory gas in the inspiratory limb (IL) and a high ratio of the maximum CO 2 content and corresponding end‐expiratory CO 2 concentration in the expiratory limb (EL) (F max CO 2 /F 2 CC 2 ) and a type 2 with no detectable alveolar gas in the IL and a low ratio of F max GO 2 /F E CO 2 . The use of PEEP did not increase the amount of alveolar gas in the system, and no increase occurred in the end‐expiratory CO 2 concentration. The investigated system is in fact a Mapleson A system. The ratio of FGF to minute ventilation just preventing rebreathing during spontaneous ventilation is approximately 1, in contrast to 3 in other modifications. These advantages minimize the risk of rebreathing, even when the minute ventilation rises to that of the fresh gas flow. The T‐system with a compliant inspiratory reservoir and a PEEP valve can, in most clinical weaning situations, satisfy the inspiratory peak flow of different respiratory patterns with a standard FGF of 15 1 × min ‐1 .