Respiratory Analysis

Evaluation of pulmo-physiologic function in conscious mice and rats by using whole body plethysmography

Whole Body Plethysmography

Since the mid-20^th century, pulmonologists have used the linear relationship between the pressure and volume of gaseous phases (the law of Boyle-Mariotte) to assess lung functions.

A specialized apparatus, the whole-body plethysmograph, permits measurements of essential ventilatory parameters leading to an evaluation of pulmonary function. Basically, this method consists of measuring the course of pressure inside the plethysmograph over time which results from the respiration of the subject. Then these pressure values can be related to distinct volumes of the respiratory cycle using the law of Boyle-Mariotte.

factec_respiration — Whole Body Plethysmograph designed for small animals

For pre-clinical purposes we provide a dual-chamber system of plethysmography consisting of a body and a head part, separated by a gas-tight seal. This setup (EMKA Technologies) allows us to measure the thoracial as well as the nasal respiratory flow of up to eight animals simultaneously. This permits measurements of ventilatory parameters including breathing rate, inspiratory/expiratory time, flow, volume, and further values of pulmonary function. For example, measurements of the specific airway resistance and conductance depend on the discrete assessment of both the nasal and thoracial respiratory flow. Ultimately, these values are necessary to evaluate most relevant diseases of the lung, such as chronic obstructive pulmonary disease (COPD) or asthmatic diseases.

In addition, the use of a head-chamber in this plethysmography system allows an optional, systematic administration of aerosolic substances like metacholine via a nebulizer unit. In this way respiratory stress models or inducible bronchodilative effects can be studied.

Whole-Body Plethysmography is non-invasive and does not rely on anesthesia. It permits measuring respiratory function in mice and rats of several sizes.

Parameters of respiratory analyses

Parameter	Description	Unit
Ti	inspiration time	ms
Te	exspiration time	ms
RT	relaxation time	ms
PIF	maximum inspiration stream	ml/s
PEF	maximum exspiration stream	ml/s
TV	tidal volume	ml
EV	exspiration volume	ml
MV	volume per minute	ml
f	breathing frequency	bpm
EIP	pause at end of inspiration	ms
EEP	pause at end of exspiration	ms
dT	nasal-thoracic lag	ms
Sraw	specific respiratory resistance	cmH₂O*s
Sgaw	specific respiratory conductance	1/cmH₂O*s
EF50	end-diastolic pressure-volume ratio	ml/s

Facility Service of Respiratory Data Analysis

As one of our special facility services, we provide comprehensive data analysis of recorded respiratory parameters. The raw data will be pre-screened in terms of signal acquisiton by technical experts and the summarized data will be sent to the customer in a neatly arranged data-sheet. At this point, the customer is free - if desired - to manually select single subjects to exclude from the study.

After selecting all subjects for analysis, the final group comparison is generated automatically. In a second sheet, all parameters are averaged per group (two groups in the standard version - ask for customized solutions!) and the final group values are displayed in a comparative view as shown in the example below. As a basic statistical analysis of group data, a T-Test based on the group-variances (type-2 or type-3) will be already included.