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We have previously reported that a dynamic air-pressure sensor system allows respiratory status to be visually monitored for patients in minimally clothed condition. The dynamic air-pressure sensor measures vital information using changes in air pressure. To utilize this device in the field, we must clarify the influence of clothing conditions on measurement. The present study evaluated use of the dynamic air-pressure sensor system as a respiratory monitor that can reliably detect change in breathing patterns irrespective of clothing. Twelve healthy volunteers reclined on a dental chair positioned horizontally with the sensor pad for measuring air-pressure signals corresponding to respiration placed on the seat back of the dental chair in the central lumbar region. Respiratory measurements were taken under 2 conditions: (a) thinly clothed (subject lying directly on the sensor pad); and (b) thickly clothed (subject lying on the sensor pad covered with a pressure-reducing sheet). Air-pressure signals were recorded and time integration values for air pressure during each expiration were calculated. This information was compared with expiratory tidal volume measured simultaneously by a respirometer connected to the subject via face mask. The dynamic air-pressure sensor was able to receive the signal corresponding to respiration regardless of clothing conditions. A strong correlation was identified between expiratory tidal volume and time integration values for air pressure during each expiration for all subjects under both clothing conditions (0.840–0.988 for the thinly clothed condition and 0.867–0.992 for the thickly clothed condition). These results show that the dynamic air-pressure sensor is useful for monitoring respiratory physiology irrespective of clothing.

Monitoring and assessing of patient respiratory function during conscious sedation are important because many drugs used for conscious sedation produce respiratory depression and subsequent hypoventilation. The purpose of this study is to assess the value of a dynamic air-pressure sensor for respiratory monitoring of clothed patients. Eight clothed adult volunteers were reclined on a dental chair positioned horizontally. The air bag for measuring air-pressure signals corresponding to respiration was placed on the seat back of the dental chair in the central lumbar area of the subject. The subject breathed through a face mask with a respirometer attached for measuring expiratory tidal volume. The air-pressure signals corresponding to respiration were obtained and the time integration values for air pressure during each expiration (integral P(exp)) were calculated. The expiratory tidal volume (TV(exp)) was measured simultaneously by respirometer. The relationship between TV(exp) and integral P(exp) for each subject was assessed by a Pearson correlation coefficient. A strong correlation between TV(exp) and integral P(exp) was observed in all subjects. Measuring integral P(exp) by dynamic air-pressure sensor makes it possible to estimate respiratory volume breath by breath, and the respiratory pressure-time integral waveform was useful in visually monitoring the respiration pattern. We believe that in the future this device will be used to monitor respiratory physiology in clothed patients, contributing to safer sedative procedures.

For dental outpatients undergoing conscious sedation, recovery from sedation must be sufficient to allow safe discharge home, and many researchers have defined "recovery time" as the time until the patient was permitted to return home after the end of dental treatment. But it is frequently observed that patients remain in the clinic after receiving permission to go home. The present study investigated "clinical recovery time," which is defined as the time until discharge from the clinic after a dental procedure. We analyzed data from 61 outpatients who had received dental treatment under conscious sedation at the Hiroshima University Dental Hospital between January 1998 and December 2000 (nitrous oxide-oxygen inhalation sedation [n = 35], intravenous sedation with midazolam [n = 10], intravenous sedation with propofol [n = 16]). We found that the median clinical recovery time was 40 minutes after nitrous oxide-oxygen sedation, 80 minutes after midazolam sedation, and 52 minutes after propofol sedation. The clinical recovery time was about twice as long as the recovery time described in previous studies. In a comparison of the sedation methods, clinical recovery time differed (P = .0008), being longer in the midazolam sedation group than in the nitrous oxide-oxygen sedation group (P = .018). These results suggest the need for changes in treatment planning for dental outpatients undergoing conscious sedation.