Table 4.

Summary of inhalation/exhalation monitoring methods used for assessing human smoking behavior (excerpted from internal company documents²⁸)

Author/Year	Method	Variables measured	Limitations
Cinkotai F.F. 196729	Partial Body Plethysmography Puff volumes and duration determined with a modified cigarette holder as a flow meter	-volume of the puff -duration of the puff -holding time of the puff in the mouth -lung volume at the beginning of the puff -time of inhalation -volume of air inhaled with the puff -volume of exhaled air -time of exhalation.	Discomfort leading to high puff by puff variation observed in the breathing patterns of individual smokers and abnormal tidal breathing caused by stress
Creighton D.E. 1978(66)	Impedance Pneumography Puff profiles and puff volumes measured with a special cigarette holder and a pressure transducer	-puff profiles and puff volumes -semi-quantitative estimates of breathing patterns	Needs calibration against a partial body plethysmograph before each use. Non linear response and day-to-day variations for individual and variation between subjects.
Guillerm R. and Radziszewski E. 1975(175)	The Guillerm and Radziszewski Method A flow meter constructed from a classic cigarette holder with a bead placed between the two snap-in-parts of the holder connected by flexible polyvinyl tubing to a differential tr ansducer. A special infrared pyrometer used to measured the temperature variations of the combustion cone of the cigarette.	-puff volume and duration -number of and intervals between puffs -volume of air taken between puffs -volume of air inhaled immediately after the puff -location of the puff in the ventilatory cycle - the breathing pattern was measured at the same time as the puff analysis	The puff volume recorded did not always correspond to the true inhaled puff volume and the technique imposed some physical restrictions on the subject, particularly concerning the cigarette holder.
Rawbone R.G. 1978(176)	Mercury Strain Gauge Chest Pneumography The puff parameters were obtained from measurements of the pressure drop across a small resistance inserted between the cigarette and the smoker. The depth of inhalation was measured by recording movements of the chest wall with a mercury strain gauge chest pneumogram.	-puff volumes, -puff duration -inter-puff interval -semi-quantitative estimates of breathing patterns	Calibration was required before each study.
Sackner M. A. 1980(177) Tobin M. J. 1982(129,143)	Respiratory Inductive Plethysmography Consisting in two coils of Teflon-insulated wire, which were sown into elastic bands encircling the rib cage and the abdomen and connected to an oscillator module. Tidal volume measured by spirometry.	-number of puffs -puff duration, -puff volumes, -integrated puff pressure. -accurate estimation of breathing patterns	Accuracy of the results depended on the initial calibration and the stability of the calibration during changes in body positions and lung volumes.