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Biomedical subjects

C F Ryan

Publications and source records attributed to C F Ryan.

At least 19 recordsLinked to original sources
PubMed2005

Craniofacial profile in Asian and white subjects with obstructive sleep apnoea.

BACKGROUND: Clinical detection of structural narrowing of the upper airway may facilitate early recognition of obstructive sleep apnoea (OSA). To determine whether the craniofacial profile predicts the presence of OSA, the upper airway and craniofacial structure of 239 consecutive patients (164 Asian and 75 white subjects) referred to two sleep centres (Hong Kong and Vancouver) were prospectively examined for suspected sleep disordered breathing. METHODS: All subjects underwent a history and physical examination with measurements of anthropometric parameters and craniofacial structure including neck circumference, thyromental distance, thyromental angle, and Mallampati oropharyngeal score. OSA was defined as an apnoea-hypopnoea index (AHI) of > or = 5/hour on full overnight polysomnography. RESULTS: Discriminant function analysis indicated that the Mallampati score (F = 0.70), thyromental angle (F = 0.60), neck circumference (F = 0.54), body mass index (F = 0.53), and age (F = 0.53) were the best predictors of OSA. After controlling for ethnicity, body mass index and neck circumference, patients with OSA were older, had larger thyromental angles, and higher Mallampati scores than non-apnoeic subjects. These variables remained significantly different between OSA patients and controls across a range of cut-off values of AHI from 5 to 30/hour. CONCLUSIONS: A crowded posterior oropharynx and a steep thyromental plane predict OSA across two different ethnic groups and varying degrees of obesity.

Analysis of Variance↗
PubMed2005

Sleep x 9: an approach to treatment of obstructive sleep apnoea/hypopnoea syndrome including upper airway surgery.

This article provides an overview of the management of the obstructive sleep apnoea/hypopnoea syndrome (OSAHS). Where possible, recommendations are based on a review of the relevant literature. With the exception of nasal continuous positive airway pressure, which is considered in greater detail elsewhere in the series, and certain oral appliances, the efficacy of many proposed treatments for OSAHS is not supported by data from randomised controlled clinical trials. To a considerable extent, treatment recommendations are based on data from uncontrolled studies, case series, consensus guidelines, practice parameters, and other less rigorous forms of evidence.

Alcohol Drinking↗
PubMed2000

Effect of cyclooxygenase-2 inhibition on renal function in elderly persons receiving a low-salt diet. A randomized, controlled trial.

BACKGROUND: Most nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit both cyclooxygenase-1 (COX-1), whose inhibition is associated with gastrointestinal ulceration, and COX-2, whose inhibition is associated with therapeutic benefits. Although agents that do not produce COX-1 activity may have fewer adverse effects, targeted disruption of the COX-2 allele in mice has resulted in severe renal problems, suggesting that COX-2 inhibition may also produce adverse effects. OBJECTIVE: To determine the effect of rofecoxib, a member of the coxib class of drugs and a specific inhibitor of the COX-2 enzyme, on renal function in elderly patients. DESIGN: A randomized, three-period, single-dose crossover study and a randomized, parallel-group, multiple-dose study. SETTING: Clinical research units. PATIENTS: 75 patients 60 to 80 years of age. INTERVENTION: In the first study, single doses of rofecoxib, 250 mg (about 5-fold to 20-fold the recommended dose); indomethacin, 75 mg; and placebo were administered to 15 patients. In the second study, multiple doses of rofecoxib, 12.5 or 25 mg/d; indomethacin, 50 mg three times daily; or placebo were administered to 60 patients. Patients in both studies received a low-sodium diet MEASUREMENTS: Glomerular filtration rate, creatinine clearance, and urinary and serum sodium and potassium values. RESULTS: Compared with placebo, single doses of rofecoxib and indomethacin decreased the glomerular filtration rate by 0.23 m/s (P < 0.001) and 0.18 mL/s (P = 0.003), respectively. In contrast, respective decreases of 0.14, 0.13, and 0.10 mL/s were observed after multiple doses of rofecoxib, 12.5 mg/d (P = 0.019); rofecoxib, 25 mg (P = 0.029), and indomethacin (P = 0.086) were administered. Changes in creatinine clearance and serum and urinary sodium and potassium were less pronounced. CONCLUSIONS: The effects of COX-2 inhibition on renal function are similar to those observed with nonselective NSAIDs. Thus, COX-2 seems to play an important role in human renal function.

Aged↗
PubMed2000

Treatment, airway and compliance effects of a titratable oral appliance.

STUDY OBJECTIVES: To measure the effects of a titratable anterior mandibular repositioner on airway size and Obstructive Sleep Apnea (OSA) and to evaluate its compliance. DESIGN: Before and after insertion sleep studies were obtained in a total of 38 OSA patients of varying severity from three different sites. Covert compliance was measured by means of a newly-developed, miniaturized, temperature-sensitive, imbedded monitor. Validity testing was completed in six adult volunteers who wore monitors imbedded into small acrylic appliances. MEASUREMENTS AND RESULTS: The mean RDI before treatment was 32.6 (SEM 2.1) and after the insertion of the appliance, the RDI was reduced to 12.1 (SEM 1.7, p<0.001). RDI was reduced to less than 15/hour in 80% of a group of moderate OSA patients (RDI 15 to 30) and in 61% of a group of severe OSA patients (RDI > 30) with respect to baseline RDI. Fiber optic video endoscopy was performed on 9 OSA patients with and without the appliance. No significant differences in hypopharynx or oropharynx cross sectional areas were found, but at the level of the velopharynx, the airway size was significantly increased (p<0.05). The index of agreement was 0.99 between the monitor clock time and the subject's log sheets. Compliance data from eight OSA subjects instructed to wear the appliance during sleep indicated that it was worn for a mean of 6.8 hours with a range of 5.6 to 7.5 hours per night. CONCLUSION: The titratable adjustable mandibular advancement appliance, made from thermoelastic acrylic, significantly reduces RDI in moderate to severe OSA patients, has a direct effect on airway size and is well worn throughout the night.

Adult↗
PubMed2000

Sleep bruxism in patients with sleep-disordered breathing.

The aim was to test the hypothesis of a direct association between sleep-disordered breathing and sleep bruxism. The frequency of masseter contraction (MC) episodes and rhythmic jaw movements (RJM) was measured in patients with mild and moderate obstructive sleep apnoea (OSA). The diagnosis of sleep bruxism was made from a combination of questionnaire, clinical observation and all-night polysomnographic recording which included masseter electromyography. A total of 21 patients (19 males/two females, mean age 40.0 years+/-9.2 SD) were randomly selected from a provisional diagnosis of snoring and OSA by a sleep physician. In the patients with mild OSA [n=11, mean apnoea hypopnoea index (AHI)=8.0+/-4.1 SD, body mass index (BMI)=29.1+/-5.0], the diagnosis of sleep bruxism was made in six out of 11 patients (54%); similarly, four out of 10 patients (40%) with moderate OSA (n=10, mean AHI=34.7+/-19.1, BMI=30.6+/-5.0) were identified as bruxists. Although the combination of clinical, subjective estimation and nocturnal electromyographic recording of masseter muscle might provide a more solid base for the diagnosis of sleep bruxism, the result is biased by the variation in the bruxing activity. MC episodes were associated with the termination of apnoea or hypopnoea episodes in only 3.5% of the mild group and 14.4% of the moderate group (p<0.05). It appears that sleep bruxism is rarely directly associated with apnoeic events, but is rather related to the disturbed sleep of OSA patients.

Adult↗
PubMed2000

Unpredictable results of laser assisted uvulopalatoplasty in the treatment of obstructive sleep apnoea.

BACKGROUND: Laser assisted uvulopalatoplasty (LAUP) is increasingly offered for the treatment of obstructive sleep apnoea (OSA), although there is a lack of objective data to support its indications and efficacy. A study was undertaken to determine the treatment response to LAUP. METHODS: Overnight polysomnography was performed before and at least three months after surgery in 44 consecutive patients with symptomatic mild to moderate OSA (apnoea + hypopnoea index (AHI) >10/h). Pharyngeal dimensions were measured by videoendoscopy (n = 11) and disease-specific quality of life, sleepiness and snoring frequency (n = 16) before and after surgery were determined in subgroups of patients. LAUP was performed under local anaesthesia as a one stage resection of the uvula and soft palate by one of two experienced otolaryngologists. RESULTS: Twelve patients (27%) had a good response (AHI </=10/h after LAUP); four (9%) had a partial response (AHI </=50% of pre-LAUP value); 15 (34%) had a poor response (AHI >50% of pre-LAUP value); and 13 (30%) patients were worse (AHI >100% of pre-LAUP value). The velopharyngeal cross sectional area and anteroposterior diameter increased following LAUP (p<0.05). Quality of life indices improved significantly in all domains and sleepiness decreased. The snoring index did not decrease significantly. No preoperative anthropometric or videoendoscopic measures were predictive of a good response to LAUP. Patients who were worse after LAUP had milder baseline apnoea severity than those in the other response groups. CONCLUSIONS: The treatment response to LAUP is variable and unpredictable, and only a few patients achieve a satisfactory response. There appears to be no relationship between subjective and objective measures of treatment efficacy.

Adult↗
PubMed1999

Mandibular posture during sleep in patients with obstructive sleep apnoea.

Vertical mandibular posture is thought to be related to narrowing of the upper airway, because mouth opening is associated with an inferior-posterior movement of the mandible and the tongue which influences pharyngeal airway patency. To test whether the mandibular posture is related to the occurrence and/or termination of obstructive sleep apnoea (OSA), the vertical mandibular position was recorded intraorally using a magnet sensor during a standard sleep study in seven patients with OSA. Measurements were recorded during sleep both in the supine and lateral recumbent positions. The percentage of total sleep time spent with mandibular opening greater than 5 mm was significantly larger (p<0.001) in patients with OSA (69.3+/-23.3%) compared with our previous results obtained from healthy adults without OSA (11.1+/-11.6%). The stage of sleep affected the vertical mandibular posture during sleep in the supine position, but not in the lateral recumbent position in patients with OSA. In non-rapid eye-movement sleep, mandibular opening increased progressively during apnoeic episodes and decreased at the termination of apnoeic episodes. In contrast, no significant change in mandibular posture occurred in apnoeic episodes during rapid eye-movement sleep. It was concluded that the vertical mandibular posture is more open during sleep in patients with OSA than in healthy adults and that mandibular opening increases progressively during apnoeic episodes and decreases at the termination of those episodes.

Analysis of Variance↗
PubMed1999

Mandibular advancement oral appliance therapy for obstructive sleep apnoea: effect on awake calibre of the velopharynx.

BACKGROUND: The mechanisms of action of oral appliance therapy in obstructive sleep apnoea are poorly understood. Videoendoscopy of the upper airway was used during wakefulness to examine whether the changes in pharyngeal dimensions produced by a mandibular advancement oral appliance are related to the improvement in the severity of obstructive sleep apnoea. METHODS: Fifteen patients with mild to moderate obstructive sleep apnoea (median (range) apnoea index (AI) 4(0-38)/h, apnoea-hypopnoea index (AHI) 28(9-45)/h) underwent overnight polysomnography and imaging of the upper airway before and after insertion of the oral appliance. Images were obtained in the hypopharynx, oropharynx, and velopharynx at end tidal expiration during quiet nasal breathing in the supine position. The cross sectional area and diameters of the upper airway were measured using image processing software with an intraluminal catheter as a linear calibration. RESULTS: AI decreased to a median (range) value of 0 (0-6)/h (p<0.01) and AHI to 8 (1-28)/h (p<0.001) following insertion of the oral appliance. The median (95% confidence interval) cross sectional area of the upper airway increased by 18% (3 to 35) (p<0.02) in the hypopharynx and by 25% (11 to 69) (p<0.005) in the velopharynx, but not significantly in the oropharynx. Although in general the shape of the pharynx did not change following insertion of the oral appliance, the lateral diameter of the velopharynx increased to a greater extent than the anteroposterior diameter. Following insertion of the oral appliance the reduction in AHI was related to the increase in cross sectional area of the velopharynx (p = 0.01). CONCLUSIONS: A mandibular advancement oral appliance increases the cross sectional area of the upper airway during wakefulness, particularly in the velopharynx. Assuming this effect on upper airway calibre is not eliminated by sleep, mandibular advancement oral appliances may reduce the severity of obstructive sleep apnoea by maintaining patency of the velopharynx, particularly in its lateral dimension.

Adult↗
PubMed1998

Mandibular posture during sleep in healthy adults.

To test whether the mandible opens more during deep sleep and whether the mandibular position is affected by body position during sleep, the vertical mandibular position was recorded intraorally using a magnet sensor at the same time as a standard sleep study in seven normal healthy male adults. Measurements were recorded during the period before sleep onset (WAKE) and during sleep. Two-way ANOVA showed that vertical mandibular position was significantly affected by sleep stage but not by body position (supine vs lateral recumbent). The proportion of time during which the mandible was in a near-closed position (0-2.5 mm) significantly and progressively decreased, and significantly more time was spent at wider gaps (2.5-5 mm) as non-rapid-eye-movement (NREM) sleep deepened. In REM sleep, the proportion of time during which the mandible was at wider gaps was significantly greater than in WAKE and stage 1 (but not later stages) of NREM sleep. It was concluded that mandibular posture during sleep in healthy adults is significantly influenced by sleep stage but not by body position. Mandibular opening progressively increases with the depth of NREM sleep stage, and the mandible is more open in REM sleep than in light NREM sleep.

Adult↗
PubMed1997

Effect of mandibular and tongue protrusion on upper airway size during wakefulness.

Oral appliances for the treatment of obstructive sleep apnea (OSA) produce either mandibular or tongue protrusion, and are thought to enlarge the upper airway (UA). We used videoendoscopy to measure UA cross-sectional area (CSA) and shape in the hypopharynx, oropharynx, and velopharynx during various stages of active mandibular and tongue protrusion during wakefulness in 10 patients with OSA and nine control subjects. Measurements were made in the supine position at end-tidal expiration, and were normalized to the CSA in the normal bite position. Airway shape was expressed as the anteroposterior/lateral (AP/L) diameter ratio. There were no differences between OSA patients and controls in the effects of mandibular and tongue protrusion on UA caliber. Both mandibular and tongue protrusion increased CSA in the hypopharynx and oropharynx (p < 0.001), whereas only tongue protrusion increased CSA in the velopharynx (p < 0.001). Tongue protrusion caused a greater increase in oropharyngeal and velopharyngeal CSA than did mandibular protrusion (p < 0.05). Mandibular protrusion caused a greater increase in CSA in the hypopharynx than in the oropharynx or velopharynx (p < 0.05). Obese patients had a larger relative increase in oropharyngeal CSA with mandibular and tongue protrusion than did subjects of normal weight. Tongue protrusion increased the AP/L diameter ratio in the oropharynx and velopharynx (p < 0.001), and mandibular protrusion did so to a lesser extent in the oropharynx (p < 0.01), resulting in a more circular airway shape. We conclude that mandibular and tongue protrusion increase the CSA and alter the shape of the UA during wakefulness.

Endoscopy↗
PubMed1996

Cephalometric comparisons of craniofacial and upper airway structure by skeletal subtype and gender in patients with obstructive sleep apnea.

To investigate whether patients with obstructive sleep apnea (OSA) have abnormalities in their craniofacial and upper airway (UA) structures compared with normal subjects, cephalometric comparisons were systematically performed in both the upright and the supine positions in subjects with and without OSA, who were then grouped according to their craniofacial skeletal type and gender. A total of 347 patients with OSA and 101 control subjects were divided into male and female groups and then classified into Class I (CI), Class II, Division 1 (CII/1), Class II, Division 2 (CII/2), and Class III (CIII) skeletal subtypes. In the upright position, the most atypical craniofacial and UA structure was shown in male patients with CI OSA. In patients with OSA, the degree of UA abnormalities was less in the supine position regardless of skeletal subtype. In the supine position, the most atypical craniofacial and UA structure was also shown in male patients with CI OSA; there were no significant differences between male patients with CII/2 OSA and control subjects or between female patients with CI OSA and control subjects. With a change in body position from upright to supine, distinctive changes in the UA structure in both patients with OSA and control subjects occurred, according to skeletal subtype and gender. We conclude that there are a series of characteristics of craniofacial and UA structure that differ between patients with OSA and control subjects matched for skeletal subtype and gender. These differences may predispose to UA obstruction during sleep in patients with OSA.

Adult↗
PubMed1996

Health status at entry to methadone maintenance treatment using the SF-36 health survey questionnaire.

This study used the SF-36 general health questionnaire to measure the health status of heroin users at entry to a public methadone maintenance programme. Their results were compared to those from the general population and from three clinical groups: patients with minor medical, major medical and psychiatric problems. One hundred consecutive clients were interviewed in the first week on the programme using the SF-36 health questionnaire. Data were also gathered on their drug use, use of medical services and HIV risk behaviour. The results showed that heroin users at entry to the methadone maintenance programme had significantly worse physical and psychological health than the general population. Their scores were most similar to the psychiatrically depressed patients, although they had worse physical health than this comparison group. The greater the amount of heroin used by clients before entering the programme, the more pain they reported. Alcohol and marijuana use were associated with better social and physical health. The relationship between general health status and amount or frequency of drug use is not a clear one. Heroin users experience severe emotional and physical problems at the time of entering methadone maintenance treatment.

Adolescent↗
PubMed1996

Improvements in retention rates and changes in client group with methadone maintenance streaming.

This study evaluated changes in client population and in retention rates following the introduction of a system of methadone maintenance streaming. A low intervention and low supervision stream was combined with two abstinence-orientated streams. Privileges of take-home doses and local pharmacy dose collection were contingent on successful participation in the abstinence-orientated streams. The clinic also modified policy to allow clients greater control over dose levels. The case notes of the first 100 clients entering the programme in the year prior to the changes (1991) and in the year following the changes (1993) were compared. The results showed a significant increase in retention rates. The demographic and heroin using histories did not change, but the newer programme attracted a greater proportion of clients with no previous history of methadone maintenance treatment. Mean clinic dose increased from 45 mg to 63 mg when clients were allowed to exert control over dose. These findings reveal improved outcomes in a public methadone maintenance programme as a result of policy changes designed to give clients greater control of their treatment.

Journal Article↗
PubMed1996

Pharmacological properties of ketamine.

Ketamine is a dissociative anaesthetic that is being used in non-medical contexts. The effects of ketamine are very similar to those of phencyclidine, another dissociative anaesthetic that has enjoyed considerable popularity as a recreational drug. The effects of ketamine include analgesia, cardiovascular and respiratory stimulation, dissociation, hallucinations and anaesthesia. The potential dangers of uncontrolled ketamine use include psychosis and violence, accidents and marked psychomotor and cognitive impairment. Although studies have shown potential for tolerance to and physical dependence on ketamine, further investigation of these phenomena is needed. Ketamine is thought to produce most of its effects through antagonist activity at the PCP site of the NMDA receptor complex. Ketamine has sympathomimetic properties resulting from enhancement of catecholamine, and particularly dopamine, activity. While opioid receptor activity has been identified, this is relatively weak and the contribution to the effects of ketamine is not clear. Although much is known of the clinical uses and effects of ketamine, as yet little is understood of ketamine as a recreational drug and potential drug of dependence.

Journal Article↗
PubMed1996

Oral appliance therapy for the treatment of obstructive sleep apnea.

A variety of oral appliances (OA) are now available for the treatment of obstructive sleep apnea (OSA), OA therapy is effective in some patients with mild to moderate OSA and is associated with greater patient satisfaction than nasal CPAP. Adjustable OA are associated with improved treatment success and fewer compliance failures compared to non-adjustable OA. Large randomized clinical trials are necessary to further determine the precise indications, benefits, and risks of each OA in the treatment of OSA.

Humans↗
PubMed1996

Mechanical properties of the velopharynx in obese patients with obstructive sleep apnea.

Epidemiologic data indicate that the relationship between obesity and obstructive sleep apnea (OSA) is largely explained by variation in neck size. Fat deposits in the neck may predispose to upper airway (UA) occlusion during sleep by altering the mechanical properties of the UA, particularly at the level of the velopharynx (VP). To determine whether effective compliance (CEFF) of the VP is related to obesity in the neck, we have performed anthropometrics, polysomnography, and dynamic UA videoendoscopy in 18 patients with OSA and eight nonapneic control subjects. Following topical anesthesia (cocaine 4%) to one nasal passage, subjects were examined with a thin fiberscope (outer diameter [OD] 3.8 mm) while awake, supine, breathing exclusively through the nose, during a maximal vital capacity (VC) maneuver against an unoccluded airway. UA cross-sectional area (CSA), anteroposterior (AP) and lateral (L) diameters were measured from stored images. CEFF was expressed as the ratio of CSAVP in expiration (E) to inspiration (I) during the maximal VC maneuver (expiratory CSAMAX/inspiratory CSAMIN), and airway shape as AP/L diameter. The OSA patients were divided into two groups based on median neck circumference (NC). CEFF of the VP was greater in OSA patients compared with control subjects (CEFF 2.0 +/- 0.8 versus 1.1 +/- 0.5; p < 0.001). CEFF was greater in the large NC group compared with both the small NC group (p < 0.05) and control subjects (p < 0.01), but the difference between the small NC group and control subjects was not significant. CEFF was related to NC (r = 0.63; p = 0.001; n = 26), body mass index (r = 0.54; p < 0.01, n = 26), and apnea-hypopnea index (r = 0.43; p < 0.05; n = 23). The change in CSAVP during the maximal VC maneuver was mainly due to inspiratory narrowing. Obese patients with large necks have a more collapsible velopharynx during wakefulness, which may predispose to upper airway obstruction during sleep.

Adult↗