Respiratory inductive plethysmography (RIP) is a method of assessing breathing pattern noninvasively, without the use of airway connections. We undertook this study to investigate the accuracy of the single-position graphic (SPG) calibration technique with the respiratory inductive plethysmograph in small animals receiving controlled mechanical ventilation. Materials and Methods: We employed the SPG calibration technique for gain-factor calculation in 5 lambs and 5 piglets receiving controlled mechanical ventilation; each animal was studied three times. The SPG technique utilizes selection of two breaths (from a 20-s run of breaths) with different rib-cage and abdomen cross-sectional areas, as indicated by the RC and AB bands, respectively, of the plethysmograph; these ratios of rib cage and abdomen areas to a volume measurement made simultaneously by pneumotachography (RC/PNT and AB/PNT, respectively) are used for gain-factor calculation. Validation of gain factors was performed by comparing the volumes of 10 breaths measured by RIP with volumes measured simultaneously by integrated PNT. Results: On the initial ventilator settings, 87% (130) of the 150 lamb breaths used for validation were within 10% of the integrated PNT volume, and 81% (121) of the 150 piglet validation breaths were within 10% of integrated PNT. Following a significant change in ventilator-delivered frequency and tidal volume, new gain-factor calculation was required in 6 of the 15 lamb studies (40%) and 9 of the 15 piglet studies (60%) because of significantly altered RC amplitude, AB amplitude, or both. On the second ventilator settings, validation runs, including those on animals requiring new gain factors, revealed 91% (137) of the 150 lamb breaths and 94% (141) of the 150 piglet breaths to be within 10% of the integrated PNT standard. Total study time ranged between 30 and 90 minutes. Conclusions: The results of this study suggest that the SPG calibration technique provides an accurate method of calibration of RIP in small, sedated animals receiving controlled mechanical ventilation. Accuracy of gains cannot be assumed following ventilator setting changes.
Get full access to this article
View all access options for this article.
References
1.
DolfinT, DufftyP, WilkesD, BryanM.Calibration of respiratory inductive plethysmography (Respitrace) in infants. Am Rev Respir Dis1982;126:577–579.
2.
DufftyP, SpiretL, BryanM, BryanH.Respiratory inductive plethysmography (Respitrace): An evaluation of its use in the infant. Am Rev Respir Dis1981;123:542–546.
3.
DolfinT, DufftyP, WilkesD, EnglandS, BryanH.Effects of a face mask and pneumotachograph on breathing in sleeping infants. Am Rev Respir Dis1983;128:977–979.
4.
FlemingPJ, LevineMR, GoncalvesA.Changes in respiratory pattern resulting from the use of a face mask to record respiration in newborn infants. Pediatr Res1982;16:1031–1034.
5.
SacknerMA. Monitoring of ventilation without physical connection to the airway: A review. In: ScottFD, RafteryDC, GouldingL, eds. Proceedings of the Third International Symposium on Ambulatory Monitoring. London: Academic Press, 1979:1–34.
6.
WarrenR, AldersonS.Calibration of respiratory inductive plethysmography (Respicomp®) in infants. Am Rev Respir Dis1985;131:564–567.
7.
WarrenR, AldersonS.Breathing patterns in infants utilizing respiratory inductive plethysmography. Chest1986;89:717–722.
8.
WarrenRH, AldersonSH. Ventilatory values measured in normal newborns by respiratory inductive plethysmography. Respir Care1985;30:174–178.
9.
CohnM, RaoA, BroudyM, et al. The respiratory inductive plethysmograph: A new non-invasive monitor of respiration. Bull Eur Physiopathol Respir1982;18:643–658.
10.
TobinM, ChadhaT, JenouriG, BirchS, GazerogluH, SacknerM.Breathing patterns. I. Normal subjects. Chest1983;84:202–205.
11.
SacknerJ, NixonA, DavisB, AtkinsN, SacknerM.Non-invasive measurement of ventilation during exercise using a respiratory inductive plethysmograph. Am Rev Respir Dis1980;122:867–871.
12.
TobinM, JenouriA, LindB, WatsonH, SchneiderA, SacknerM.Validation of respiratory inductive plethysmo-graphy in patients with pulmonary disease. Chest1983;127:615–620.
13.
CohnMA, WatsonHL, WeisshartR, ScottFD, SacknerMA. A transducer for non-invasive monitoring of respiration. In: ScottFD, RafteryEB, SleightP, GouldingL, eds. Proceedings of the Second International Symposium on Ambulatory Monitoring. London: Academic Press, 1978:119–128.
14.
KonnoK, MeadJ.Measurement of the separate volume changes of ribcage and abdomen during breathing. J Appl Physiol1967;22:407–422.
15.
WatsonH.The technology of respiratory inductive plethysmography. In: ScottFD, RafteryCB, GouldingL, eds. Proceedings of the Third International Symposium on Ambulatory Monitoring. London: Academic Press, 1979:48–65.
16.
ChadhaT, WatsonH, BirchS, et al. Validation of respiratory inductive plethysmography using different calibration procedures. Am Rev Respir Dis1982;125:644–649.
17.
AbrahamW, WatsonH, SchneiderA, KingM, YergerL, SacknerM.Non-invasive ventilatory monitoring by respiratory inductive plethysmography in conscious sheep. J Appl Physiol1981;51:1657–1661.
18.
TobinMJ, JenouriG, BirchS, et al. Effect of positive end-expiratory pressure on breathing patterns of normal subjects and intubated patients with respiratory failure. Crit Care Med1983;11:859–867.
19.
LoveridgeB, WestP, AnthonisenN, KrygerM.Breathing patterns in patients with chronic obstructive pulmonary disease. Am Rev Respir Dis1984;130:730–733.
20.
RodensteinD, MercenierC, StanescuD.Influence of the respiratory route on the resting breathing pattern in humans. Am Rev Respir Dis1985;131:163–166.
