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Biomedical subjects

J S Haight

Publications and source records attributed to J S Haight.

At least 19 recordsLinked to original sources

Comparison of direct and indirect measurements of respiratory airflow: implications for hypopneas.

The purpose of this study was to compare indirect methods for measuring respiratory airflow, such as temperature difference between inspired and expired air, thoracoabdominal movements, and nasal respiratory-airflow pressures-with a more direct measurement of minute ventilation using a head-out body plethysmograph. Measurements were obtained in healthy, awake, seated subjects during sequences of different levels of voluntary hypoventilations at 20 breaths/minute and analyzed to determine how well different methods could identify hypopneas (defined as reduction in minute ventilation by 50% or more). The results varied widely between different methods. Sensitivities ranged from 0 to 1, specificity ranged from 0.33 to 1, positive predictive values (PPV) ranged from 0 to 0.73, negative predictive values (NPV) ranged from 0.68 to 0.93. Cohen's kappa varied between 0 and 0.65 The poorest agreement was for the thermistor method, and the best agreement was obtained when a combination of thoraco-abdominal movements and nasal respiratory-airflow pressure was employed (sensitivity = 0.86, specificity = 0.83, PPV = 0.71, NPV = 0.92, Cohen's kappa = 0.65). We conclude that none of the indirect methods investigated, individually or in combination, proved adequate for identification of voluntary hypopneas in awake individuals.

Humans

A comparison between two methods of measuring pressure in the pharyngeal airway: transducer probe versus open catheter.

A new multi-transducer probe system for measuring pharyngeal pressures was compared with an established open catheter system. Pharyngeal pressure measurements were made at the same time, and site, in subjects awake, at unmodified and with artificially increased nasal airway resistances, and during sleep documented by polysomnography. The two systems yielded almost identical results. It is anticipated that the multi-transducer probe system will prove of clinical value.

Adult

Pharyngeal airflow during sleep.

This study was conducted to investigate the effects of sleep and nasal resistance on pharyngeal airflow in a group of healthy male adults without complaint of habitual snoring. Twelve subjects aged 21 to 60 years were studied in a sleep laboratory during exclusive nasal breathing. Nasal and pharyngeal airflow variables were measured concomitantly at different stages of sleep. Awake pharyngeal resistance averaged 0.02-0.03 Pa/cm3/s in recumbency. In stage 2 sleep and quiet breathing resistance increased by a factor of 3-4 and by a factor of 7-8 during snoring. Increased nasal loading did not increase pharyngeal resistance further or induce snoring. Mostly, increased pharyngeal resistances were of similar magnitude in both phases of respiration, but in a few instances inspiratory resistance exceeded that in expiration, and in a similar number the reverse was found. Overall, compliance of the pharyngeal airway was not a prominent feature in this group of subjects. The relationship between transpharyngeal pressure and resistance should be studied further in order to simplify future studies of airflow during sleep.

Adult

Diagnostic airway pressure recording in sleep apnea syndrome.

A comparison was made between polysomnographic recordings and recordings of airflow pressures in the pharynx and respiratory pressures in the esophagus of 10 adult sleeping subjects with differing degrees of apnea. Pressure measurements were obtained by microsensors mounted on a 7F gauge flexible catheter which sited them in the epi-, meso- and hypopharynx and the esophagus. Digitized overnight pressure data were stored on a PC memory card and subsequently displayed for analysis by means of a notebook computer. In 2 patients examination of 200 obstructive, mixed and central apneic events showed no significant differences in recordings of their incidence, duration of classification between polysomnographic and either pharyngeal or esophageal pressure techniques. Onset of apnea was demonstrated with particular clarity by computer integration of the pressure tracings. The multiple pressure sensor method offered a further important advantage in detecting the caudal limits of pharyngeal obstructions by steep elevation of the pressure gradient in the pharyngeal segment between adjacent sensors in which the caudal limit of the obstruction was sited. The multiple pressure sensor technique provided reliable and comprehensive diagnostic information of breathing disorders in sleeping subjects and together with its miniaturized recording equipment the method commends itself as suitable for home monitoring.

Adult

Nasal resistance in recumbency and sleep.

Nasal resistances to respiratory airflow were measured by computer-assisted rhinomanometry in 21 adult males without major clinical nasal pathology. Measurements were obtained when seated and repeated on assumption of recumbency and during sleep. Resistance in Pa/cm3/s of subjects (n = 21) increased from a mean (+/- SD) of 0.14 +/- 0.07 in seated posture to 0.35 +/- 0.32 in recumbency. In the majority of subjects the increase was modest and was unaffected by sleep. It is suggested that unrecognized mucosal abnormality with resulting impairment of vascular tone or minor structural deviation of the nasal septum could account for the few cases of marked elevation of nasal resistance we observed in recumbency.

Adult

Subjective and objective assessment of uvulopalatopharyngoplasty for treatment of snoring and obstructive sleep apnea.

This study was designed to assess the subjective and objective effects of uvulopalatopharyngoplasty (UPPP) for treatment of snoring. We mailed a questionnaire dealing with snoring, quality of sleep, and interference with bed-partner's sleep to 100 unselected patients who were referred because of snoring. Replies were received from 69 patients. The answers were analyzed, and the subjective impressions were compared with preoperative and postoperative objective measurements of snoring and apnea. The average (+/- SD) length of follow-up was 45 +/- 20 mo. We found no significant differences in the apnea/hypopnea index, snoring index, and mean and maximal nocturnal sound intensity before and after surgery in this group. However, despite this lack of objective improvement. 78% of patients reported reduction in snoring, and 79% reported improvement in the quality of sleep; 18 of 69 bed partners no longer complained of interference with their sleep compared with only one preoperatively. We conclude that if the purpose of UPPP is to reduce the reported health hazards associated with snoring, then comparison between objective preoperative and postoperative measurements of snoring does not indicate success; if, on the other hand, the purpose of surgery is to alleviate the social hazard, then UPPP partially achieves this goal.

Adolescent

Sleep and posture.

Computer-assisted open catheter studies of 10 healthy, nose-breathing men in dorsal and in lateral recumbent sleep demonstrated stable intrasubject transpharyngeal differential pressures and airflow resistances. They averaged 19.6 Pa (+/- standard deviation [SD] 11.9) and 0.103 Pa/cm3 per second (+/- SD 0.065) in the dorsal posture and stage II sleep during quiet breathing and were not significantly different in the lateral posture or in stage I sleep. Five subjects were snorers, and their pharyngeal airflow pressures and resistances increased substantially during quiet breathing on assumption of recumbency and much more in sleep. In the 5 subjects who were nonsnorers, postural changes were not significant and sleep increases were moderate. During snoring, transpharyngeal pressures and resistances increased even further, averaging 188 Pa and 1.02 Pa/cm3 per second for the whole group. Transpharyngeal differential pressures and hypopharyngeal transmural pressures frequently exceeded 300 Pa in inspiration and in expiration during periods of snoring. Yet, transpharyngeal differential pressures and resistances did not reveal appreciable differences between phases that would indicate compliant change of pharyngeal cross section. Breathing frequency was unchanged, but ventilation was significantly diminished at elevated upper airway resistances (P < .01). Transpharyngeal resistances and differential pressures varied independently from widely differing nasal resistances. As with our earlier studies, pressure measurements alone clearly demonstrated breathing patterns and events.

Adult

Resistance to respiratory airflow of the extrapulmonary airways.

Resistances to respiratory airflow of nasal, pharyngeal, laryngeal, and tracheobronchial airway segments were determined by computer processing of digitized differential pressure and flow signals in four healthy, awake, male adults seated and breathing spontaneously at rest, exclusively through decongested noses. Resistances of the nasal and pharyngeal segments in Pa/cm3 per second averaged 0.139 (SD +/- 0.044) and 0.081 (SD +/- 0.051), respectively, with no resistive evidence of compliance with airflow pressures. The laryngeal segment exhibited the reciprocal of compliance, expiratory resistances exceeded those of inspiration, averaging 0.125 (SD +/- 0.037) and 0.035 (SD +/- 0.013), respectively (.005 < P < .01). Tracheobronchial resistances during spontaneous resting breathing were too small to record reliably at the calibration used, and values augmented by voluntary hyperventilation averaged only 0.012 (SD +/- 0.004). Laryngeal expiratory resistance approximated one fifth of the sum total of respiratory airflow resistances (including the pulmonary airways) and the authors suggest that, in addition to contributing to expiratory airflow braking, partial laryngeal closure induces orifice flow. This nonlaminar flow regime promotes the mucosal contact and mixing that enables greater than 30% of heat and water to be recovered from expiratory air by the human pharynx and nose.

Adult

Laryngeal resistance to respiratory airflow in humans.

Although vocal cord adduction has been observed during expiration, measurements of absolute values of resistance changes in man have not been reported in the literature. The authors measured resistance to translaryngeal respiratory airflow in inspiratory and expiratory phases of the respiratory cycle of four healthy, awake men during nasal breathing. It was found that, during quiet breathing through a decongested nose, translaryngeal resistance was 1.245 cm H2O/L per second in expiration and 0.354 cm H2O/L per second in inspiration (.005 < P < or = .01), for a percentage of approximately 25% and 50% of extrathoracic expiratory and inspiratory resistances, respectively. Voluntary hyperventilation decreased expiratory resistance, and a partial nasal obstruction abolished the statistical difference between translaryngeal inspiratory and expiratory resistance. These results are in agreement with previous observations of vocal cord movement and are consistent with an expiratory braking effect on airflow.

Adult

Snoring and nasal resistance during sleep.

Although it is widely accepted that nasal obstruction leads to snoring and sleep apnea, the relationship between these variables is not clear, mainly because of the lack of studies in which nasal resistance (Rna) and snoring were measured concurrently. The authors studied eight nonapneic snoring men with healthy noses by nocturnal polysomnography that included quantitative assessment of snoring and concomitant nasal resistance. In six of these eight patients nasal resistance increased during sleep, but there was no significant change for the group as a whole between wakefulness (0.209 +/- 0.224 Pa/cm3 per second) and sleep (0.292 +/- 0.203 Pa/cm3 per second). Linear regression analysis showed no significant correlation between sleeping nasal resistance and snoring index (partial R2 = .44, P = .071). We used each subject as his own control and compared the snoring profile at a time during sleep when nasal resistance was at its highest (0.550 +/- 0.375 Pa/cm3 per second) and lowest (0.146 +/- 0.090 Pa/cm3 per second) levels. Despite the significant (P < .01) differences in nasal resistance, they were not reflected in the number of snores or their sound intensity. It is concluded that nasal obstruction during sleep is not correlated significantly to frequency or intensity of snoring during exclusively nasal breathing.

Adult

Site of airway obstruction in patients with obstructive sleep apnea before and after uvulopalatopharyngoplasty.

This study describes a simple method, based on a movable catheter technique, for use during routine polysomnography to identify the site of obstruction, and this has been applied to 51 patients with suspected sleep apnea. The obstruction was found to be retropalatal in 30, retrolingual in 7, and could not be determined in 14 patients (12 had no sleep apnea, 1 did not sleep, and 1 had central sleep apnea). Twelve of these patients had uvulopalatopharyngoplasty with preoperative and postoperative polysomnograms to determine the site of obstruction. The preoperative obstruction was retropalatal in nine and retrolingual in three. Postoperatively, four patients (one with retrolingual obstruction and three with retropalatal obstruction) no longer had sleep apnea. In the remaining eight patients, the site of obstruction was unchanged from the preoperative one. Several conclusions result: 1. the movable catheter technique offers a simple way to determine the site of obstruction in patients with significant obstructive sleep apnea, 2. most such patients obstruct in the retropalatal region, and 3. preoperative localization of the site of obstruction to the retropalatal region does not seem to improve the surgical outcome of uvulopalatopharyngoplasty.

Adult

Resolution of obstructive sleep apnea following facial surgery.

Compared to uvulopalatopharyngoplasty (UPPP), maxillo-facial surgery is rarely performed in Canada for treatment of obstructive sleep apnea. However, in patients with retrolingual obstruction, UPPP cannot be expected to result in good surgical outcome. We describe a patient with retrognathia causing airway obstruction at the base of the tongue, in whom sagittal mandibular osteotomy with hyoid bone advancement resulted in resolution of snoring and sleep apnea.

Adult

Snoring, apnea and nasal resistance in men and women.

To examine if gender and airway resistance (nasal and pulmonary) influence the loudness and intensity of snoring, we prospectively studied 370 unselected patients referred to our sleep clinic because of heavy snoring and a possibility of sleep apnea. All patients had full nocturnal polysomnography, including measurements of snoring using a calibrated microphone-sound meter system, and determination of pulmonary (Raw) and nasal resistance (Rna). Snoring was quantified by reporting the number of snores per hour of sleep (snoring index--SI) and the maximum nocturnal sound intensity (dBmax). The patient population comprised 77 females and 293 males, ranging in age from 12 to 80 years. Based on the apnea/hypopnea index (AHI) we separated all patients into the apneic and non-apneic groups. There were 201 non-apneic snorers (AHI less than or equal to 10) and 160 apneic snorers (AHI greater than 10). There was no significant difference in snoring frequency, maximum nocturnal sound intensity, nasal and pulmonary resistance between men and women or between apneic and non-apneic snorers. Stepwise, forward, multiple linear regression analysis showed that body mass index and nasal resistance correlate significantly with the snoring index (R2 = 0.29, p less than 0.005), while age and body mass index correlate only weakly, but significantly, with the maximum nocturnal sound intensity. We conclude that (1) men snore similarly to women, and (2) obesity and nasal resistance are important determinants of the frequency of snoring. It follows that measures taken to reduce weight and decrease nasal resistance may be of benefit in reducing snoring.

Adolescent

Is the nasal cycle an artifact? The role of asymmetrical postures.

Both the nasal cycle and postural asymmetries between the lateral halves of the body will cause the patent cavity of the nasal airway to change sides. Therefore, the cycle might result from adjustments of posture during prolonged periods of nasal resistance measurements. Posterior rhinometric measurements of unilateral nasal resistance were made three times for 5 to 7 hours on a patient in whom 11 periods of lateral recumbency had not induced nasal resistance changes. A nasal cycle was observed. It is concluded that the cycle is not the product of asymmetrical body pressures.

Adult

Nasal cryosurgery and cautery: should the septum be treated and is a diagnosis relevant?

Posterior rhinometric measurements of nasal resistance were conducted on two groups of patients with perennial rhinitis: those whose symptom of nasal stuffiness responded to a topical steroid spray and those in whom it did not. The anterior ends of the inferior turbinates in 48 patients were treated with either cryosurgery or cautery, and in half of the subjects the erectile tissue of the septum was also thermally ablated. Measurements were made before and 10-16 weeks after therapy. It is concluded from statistical comparison that there is no benefit to treating the septum, and that cryosurgery is more effective in those whose symptoms respond to topical steroids, while cautery works better in those who do not. Histology showed no change in the capacitance vessels (sinusoids) after either modality, and xylometazoline caused a marked decrease in nasal resistance, suggesting that vascular smooth muscle function was intact. Irrespective of the change in airway resistance, most subjects felt that there had been an improvement. The mechanism is discussed.

Adult

Unilateral nasal resistance and asymmetrical body pressure.

Lateral recumbency causes ipsilateral nasal congestion and contralateral decongestion. Nasal resistances were measured before, during and after the application of pressure either regionally or by lateral recumbency. In some experiments an attempt was made to block the response by local anesthetic injection, splinting the nasal vestibules, or topical decongestants. In others an electric blanket was employed as a stimulus instead of pressure. It was concluded that the nasal resistance changes during lateral recumbency are due to pressure receptors in the pelvic and pectoral girdles, and thorax. These adapt slowly. They are probably situated in the intercostal spaces, parietal pleura, or sterno-costal joints. Their centripetal fibers probably travel in the intercostal nerves, and their efferents in the cervical sympathetic outflow to the nasal erectile tissue. Lateral recumbency of 12 minutes' duration induces changes in nasal resistance which persist after the pressure asymmetry has been terminated. This may be due to temporal summation.

Adult

Reversible obstructive sleep apnea caused by occupational exposure to guar gum dust.

This report describes a case of reversible obstructive sleep apnea caused by occupational exposure to an inhaled allergen, guar gum powder. The patient, a pet food plant employee, also experienced severe cough, rhinitis, and conjunctivitis. Skin tests confirmed the specific guar allergy. Pharyngeal cross-sectional area was smaller than normal. Pulmonary function studies, histamine challenge tests, nasal air-flow resistance measurements, and nocturnal polysomnography were performed on 3 separate occasions: while the patient was working at his usual occupation, at the end of a 3-wk holiday, and after a guar dust challenge in an inhalation chamber. Pulmonary function and histamine challenge tests were consistently normal. At the time of the initial tests, nasal resistance was elevated, and nocturnal polysomnography revealed obstructive sleep apnea. After absence from work, obstructive sleep apnea resolved, and the nasal resistance returned to normal. After challenge with guar gum dust, the patient developed increased resistance to nasal air flow, and obstructive sleep apnea reappeared. This case demonstrates that allergy can cause reversible obstructive sleep apnea and that occupational exposure should be considered in the assessment of patients with this disease.

Adult