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Biomedical subjects

M Tvinnereim

Publications and source records attributed to M Tvinnereim.

9 recordsLinked to original sources
PubMed1996

Postural changes in respiratory airflow pressure and resistance in nasal, hypopharyngeal, and pharyngeal airway in normal subjects.

We investigated the effect of posture on nasal and pharyngeal resistance in 12 healthy subjects studied during wakefulness. Airway pressure and airflow were measured with subjects seated and in dorsal and left lateral recumbency, during inspiration and expiration. We found that pharyngeal resistance was approximately four to six times lower than the nasal resistance. Only pharyngeal resistance was significantly increased upon assumption of a supine posture, from 0.02 +/- 0.01 Pa/mL per second when seated to 0.06 +/- 0.05 Pa/mL per second in dorsal recumbency and to 0.05 +/- 0.04 Pa/mL per second in left lateral recumbency. Mean nasal and pharyngeal resistances doubled upon assumption of a supine posture, but this difference was not statistically significant. There was no significant difference in pharyngeal resistance between inspiration and expiration. Finally, there was a strong linear relationship between pharyngeal pressure and pharyngeal resistance (r = .98, p<.0001). We concluded that in normal awake subjects 1) pharyngeal resistance increases with assumption of a supine posture, 2) the walls of the pharynx are not compliant enough to alter their resistance in response to inspiratory and expiratory pressure changes, and 3) it may be possible to infer pharyngeal resistance from measurements of pressure alone, without measurement of airflow.

Adult↗
PubMed1995

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↗
PubMed1995

Diagnosis of obstructive sleep apnea using a portable transducer catheter.

As an initial step in simplifying the diagnosis of sleep apnea with a view toward using portable equipment in the home setting, we examined the efficacy of a portable transducer catheter that measures intrathoracic pressure. This catheter, connected to a miniature data-logger, can be introduced nasally into the airway, and the data so collected can be acquired, stored, and analyzed off-line. We tested this catheter against standard nocturnal polysomnography in 10 patients suffering from obstructive sleep apnea. We found that by using a combination of the raw pressure signal and an envelope pressure signal, we accurately identified apneas and hypopneas, and classified them as obstructive, central, and mixed. For the 10 subjects studied, the polysomnographic apnea/hypopnea index was 34 + 30, versus 32 + 28 obtained by analysis of the pressure tracings. Analysis of 200 respiratory events identified one-by-one from polysomnograms and pressure tracings revealed close correspondence between the two methods. The average duration of apneas was 22.1 + 6.7 s as measured by polysomnography, versus 21.9 + 6.6 s as measured from pressure tracings. Furthermore, there was excellent agreement between the two methods (kappa = 0.89, 95% confidence limits = 0.84 to 0.94). We conclude that our technique for identifying apnea based on measurements of intrathoracic pressure using a thin, portable transducer catheter is a promising method for simplifying the diagnosis of this disorder.

Adult↗
PubMed1995

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↗
PubMed1994

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↗
PubMed1992

Uvulopalatopharyngoglossoplasty (UPPGP) in the treatment of the obstructive sleep apnea syndrome.

Out-patient polysomnography was conducted prior to surgery in 26 male, obstructive sleep apnea patients. Resection of lateral aspects of the tongue base and conservation of the proximal part of the uvula muscle were carried out in addition to conventional palatopharyngoplasty. At a minimum of 6 months after surgery, the patients were given a questionnaire for assessment of treatment. At the same time, polysomnography was repeated for objective evaluation of the results of surgery. More than 90% of the patients were satisfied with the outcome of treatment. The objective results by means of apnea index and oxygen desaturation index matched the patients' personal experiences, which is not usual in this kind of treatment. Sixty-seven percent of the obstructive sleep apnea patients achieved more than a 50% reduction in apnea index and oxygen desaturation index. No more side effects than for similar surgical intervention (PPP) were encountered. Safety and efficiency lead us to recommend this procedure as standard whenever oropharyngeal surgery is indicated.

Follow-Up Studies↗
PubMed1992

Pressure recordings--a method for detecting site of upper airway obstruction in obstructive sleep apnea syndrome.

Polysomnography is the method of choice in diagnosis of obstructive sleep apnea syndrome (OSAS) establishing whether a patient has apneas or not. It does not, however, give any indications of where the obstructions occur. This is reflected in the limited success rate of current surgical procedures used in the treatment of this disorder. We have developed a simple method for simultaneous determination of OSAS and site of obstruction. The method implies continuously recording of pressure at different sites in pharynx. A catheter with five pressure transducers and corresponding markings is put into the pharynx through the nasal cavity and interfaced with a polygraph. Continuous pressure registrations were made in 12 patients. We have found characteristic patterns of pressure-changes which clearly indicate the level of obstruction. This may be of importance in selecting patients for further treatment.

Air Pressure↗