The Journal of Laryngology and Otology June 1990, Vol. 104, pp. 473-476
Nasal airflow in inspiration and expiration LAURA VIANI M . S C ,
F.R.C.S.I.,
ANDREW
S. JONES M.D., F.R.C.S.,
RAY CLARKE
M.B.,
B.CH.
(Liverpool)
Abstract
Inspiratory and expiratory airflow rates were measured in 30 subjects during quiet respiration (at a pressure gradient of 150 Pa) and at peak flow rates. For low flow rates airflow rate was greater for inspiration than for expiration. Conversely at peak flow rates flow was greatest during expiration. Thus there was a reversal in the phase relationship between inspiration and expiration as flow rate increased. It was also found that peak inspiratory flow rate correlated better with values for nasal resistance than did peak expiratory flow rate. Flow rate measured by rhinomanometry during quiet respiration was more sensitive to physiologically induced changes in nasal resistance than was peak flow rate. The findings are discussed with reference to previous work on the physiology of nasal airflow.
considerable practical significance and are thus also considered in the present study.
Introduction
Nearly 70 years ago Mink (1920) noted that the soft portion of the external nose compressed on deep inspiration. He stated that because of this effect a constant volume of air passed through the nose per unit time. This observation implied that the nose had a higher resistance during inspiration than during expiration. A similar state of affairs may exist even at low flow rates. Haight and Cole (1983) noted that during quiet respiration the resistance of the nasal passages to airflow was also higher during inspiration; an inspiratory to expiratory ratio of 1.26 (±0.16) being quoted. As significant alar collapse only occurs in the normal nose at high flow rates the difference between resistance values for inspiration and for expiration should be maximal when peak flow rates are being measured. Kenyon (1987) also noted a phase difference in the resistance of the nose for inspiration and expiration but this time observed the converse; expiratory resistance being higher than inspiratory resistance. The reason for the conflicting results is not clear and one of the purposes of the present study was to attempt to resolve this issue. The work is further extended by measuring objective nasal patency for inspiration and for expiration at four points in the respiratory cycle. 1) At low inspiratory and expiratory flow rates corresponding to a pressure gradient of 150 Pa. 2) At maximal inspiratory and expiratory flow rates (i.e. peak flow rates). Peak flow rate estimations are quick, simple and cheap to perform and are gradually replacing rhinomanometry in the routine assessment of objective nasal patency (Benson, 1971; Taylor et ai, 1973; Davies, 1978; Youlten, 1983; Gleeson etal., 1986; Frolund etal, 1987). Because of this any large difference between peak flow values for inspiration and expiration would be of
Subjects and methods
Thirty subjects (16 male and 14 female, age range 18-60 years, mean range 32 years) were recruited from the staff of the Royal Liverpool Hospital, Liverpool. There was no history of nasal disease and all had normal nasal cavities on anterior rhinoscopy. All subjects had four respiratory parameters measured: 1) & 2) Total nasal resistance to airflow measured by anterior rhinomanometry. Both inspiratory and expiratory phases being measured [RnAi and RnAe]. 3) Peak nasal inspiratory flow rate [PnlFR]. 4) Peak nasal expiratory flow rate [PnEFR]. Each of the above measurements was made in all subjects. In addition ten subjects (five male and five female, mean age 28 years) had all the measurements performed before and immediately after exercise. Each subject performed exercise at a rate of 120 watts for five minutes using a calibrated bicycle ergometer. It is well known that the resistance of each nasal cavity varies with time by a factor of ten (Eccles, 1978) but that the total nasal resistance is relatively constant (Eccles, 1978; Jones et al., 1987). Nevertheless total nasal resistance does vary with time by a factor of two (Jones etal., 1987) and thus will not be the same for all the tests in each subject. In order to eliminate this effect the subjects had the various tests performed in random order; randomisation being achieved with reference to a computer-generated random number table. In addition all measurements where made in constant conditions of temperature, humidity and posture (Eccles, 1978; Jones and Lancer, 1987); the patient being seated in a comfortable chair
Accepted for publication: 12 March 1990. 473
474
L. VIANI, A. S. JONES AND R. CLARKE
throughout the period that the measurements were being performed. 1) & 2) Active anterior rhinomanometry was undertaken according to a standard protocol (Jones etal, 1987; Stevens et al., 1987) using a Mercury Electronics NR6 Rhinomanometer system (Mercury Electronics [Scotland] Ltd, Pollock Castle Estate, Newton Mearns, Glasgow G77 6NU). The method used in the present study differed from the above protocol in that the mean of four measurements was taken as the nasal resistance value and calibration was greatly simplified by the use of a Mercury Electronics Rhinomanometer Calibrator (Type FP1 4632). Resistance was measured in both the inspiratory and expiratory phases. All measurements were taken at a pressure sample point of 150 Pa. 3) PnlFR was measured using a Youlten Peak Nasal Inspiratory Flow Meter (Clement Clarke International Ltd, 15 Wigmore Street, London W1H 9LA). The subject was instructed to make a maximal inspiratory effort through the nose with the mouth closed. Three measurements were made and the maximum value taken as PnlFR. 4) Measurement of PnEFR was carried out using a Mini Wright Peak Flow Meter (Clement Clarke International Ltd) The peak flow meter was adapted to connect to a nasal face mask as used for measuring PnlFR. The subject was instructed to make a maximal sustained 300'
250
Nasal airflow in inspiration and expiration LAURA VIANI M . S C ,
F.R.C.S.I.,
ANDREW
S. JONES M.D., F.R.C.S.,
RAY CLARKE
M.B.,
B.CH.
(Liverpool)
Abstract
Inspiratory and expiratory airflow rates were measured in 30 subjects during quiet respiration (at a pressure gradient of 150 Pa) and at peak flow rates. For low flow rates airflow rate was greater for inspiration than for expiration. Conversely at peak flow rates flow was greatest during expiration. Thus there was a reversal in the phase relationship between inspiration and expiration as flow rate increased. It was also found that peak inspiratory flow rate correlated better with values for nasal resistance than did peak expiratory flow rate. Flow rate measured by rhinomanometry during quiet respiration was more sensitive to physiologically induced changes in nasal resistance than was peak flow rate. The findings are discussed with reference to previous work on the physiology of nasal airflow.
considerable practical significance and are thus also considered in the present study.
Introduction
Nearly 70 years ago Mink (1920) noted that the soft portion of the external nose compressed on deep inspiration. He stated that because of this effect a constant volume of air passed through the nose per unit time. This observation implied that the nose had a higher resistance during inspiration than during expiration. A similar state of affairs may exist even at low flow rates. Haight and Cole (1983) noted that during quiet respiration the resistance of the nasal passages to airflow was also higher during inspiration; an inspiratory to expiratory ratio of 1.26 (±0.16) being quoted. As significant alar collapse only occurs in the normal nose at high flow rates the difference between resistance values for inspiration and for expiration should be maximal when peak flow rates are being measured. Kenyon (1987) also noted a phase difference in the resistance of the nose for inspiration and expiration but this time observed the converse; expiratory resistance being higher than inspiratory resistance. The reason for the conflicting results is not clear and one of the purposes of the present study was to attempt to resolve this issue. The work is further extended by measuring objective nasal patency for inspiration and for expiration at four points in the respiratory cycle. 1) At low inspiratory and expiratory flow rates corresponding to a pressure gradient of 150 Pa. 2) At maximal inspiratory and expiratory flow rates (i.e. peak flow rates). Peak flow rate estimations are quick, simple and cheap to perform and are gradually replacing rhinomanometry in the routine assessment of objective nasal patency (Benson, 1971; Taylor et ai, 1973; Davies, 1978; Youlten, 1983; Gleeson etal., 1986; Frolund etal, 1987). Because of this any large difference between peak flow values for inspiration and expiration would be of
Subjects and methods
Thirty subjects (16 male and 14 female, age range 18-60 years, mean range 32 years) were recruited from the staff of the Royal Liverpool Hospital, Liverpool. There was no history of nasal disease and all had normal nasal cavities on anterior rhinoscopy. All subjects had four respiratory parameters measured: 1) & 2) Total nasal resistance to airflow measured by anterior rhinomanometry. Both inspiratory and expiratory phases being measured [RnAi and RnAe]. 3) Peak nasal inspiratory flow rate [PnlFR]. 4) Peak nasal expiratory flow rate [PnEFR]. Each of the above measurements was made in all subjects. In addition ten subjects (five male and five female, mean age 28 years) had all the measurements performed before and immediately after exercise. Each subject performed exercise at a rate of 120 watts for five minutes using a calibrated bicycle ergometer. It is well known that the resistance of each nasal cavity varies with time by a factor of ten (Eccles, 1978) but that the total nasal resistance is relatively constant (Eccles, 1978; Jones et al., 1987). Nevertheless total nasal resistance does vary with time by a factor of two (Jones etal., 1987) and thus will not be the same for all the tests in each subject. In order to eliminate this effect the subjects had the various tests performed in random order; randomisation being achieved with reference to a computer-generated random number table. In addition all measurements where made in constant conditions of temperature, humidity and posture (Eccles, 1978; Jones and Lancer, 1987); the patient being seated in a comfortable chair
Accepted for publication: 12 March 1990. 473
474
L. VIANI, A. S. JONES AND R. CLARKE
throughout the period that the measurements were being performed. 1) & 2) Active anterior rhinomanometry was undertaken according to a standard protocol (Jones etal, 1987; Stevens et al., 1987) using a Mercury Electronics NR6 Rhinomanometer system (Mercury Electronics [Scotland] Ltd, Pollock Castle Estate, Newton Mearns, Glasgow G77 6NU). The method used in the present study differed from the above protocol in that the mean of four measurements was taken as the nasal resistance value and calibration was greatly simplified by the use of a Mercury Electronics Rhinomanometer Calibrator (Type FP1 4632). Resistance was measured in both the inspiratory and expiratory phases. All measurements were taken at a pressure sample point of 150 Pa. 3) PnlFR was measured using a Youlten Peak Nasal Inspiratory Flow Meter (Clement Clarke International Ltd, 15 Wigmore Street, London W1H 9LA). The subject was instructed to make a maximal inspiratory effort through the nose with the mouth closed. Three measurements were made and the maximum value taken as PnlFR. 4) Measurement of PnEFR was carried out using a Mini Wright Peak Flow Meter (Clement Clarke International Ltd) The peak flow meter was adapted to connect to a nasal face mask as used for measuring PnlFR. The subject was instructed to make a maximal sustained 300'
250
