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PubMed2002

The use of auto-titrating continuous positive airway pressure for treatment of adult obstructive sleep apnea. An American Academy of Sleep Medicine review.

This paper reviews the efficacy of auto-titrating continuous positive airway pressure (APAP) for treatment of obstructive sleep apnea. It is based on a review of 30 articles published in peer review journals conducted by a task force appointed by the American Academy of Sleep Medicine to develop practice parameters for use of APAP devices for treatment of obstructive sleep apnea (OSA). The data indicate that APAP can be used to treat many patients with OSA (auto-adjusting) or to identify an effective optimal fixed level of continuous positive airway pressure (CPAP) for treatment (auto-titration). Patients with significant congestive heart failure, chronic obstructive pulmonary disease (COPD), or significant amounts of central apnea were excluded from many treatment trials and there is insufficient evidence that APAP can be used to treat these patients. Many clinical trials have been performed in patients already on CPAP or with the initial APAP night in a laboratory setting. At this time only a few studies have evaluated initial titration with APAP in CPAP-naïve patients in an unattended setting. Further studies of APAP in this circumstance are needed. No studies have systematically compared the efficacy of one APAP technology with another. Devices using different technology may not give the same results in a given patient. Devices solely dependent on vibration may not work in non-snorers or patient who have undergone upper-airway surgery. High mask or mouth leaks may prevent adequate titration in devices monitoring snoring, flow, or impedance (forced oscillation technique). Review of the raw data to identify periods of high leak was performed in several of the APAP titration studies, to identify a pressure for fixed CPAP treatment or to determine if the titration was adequate. There is conflicting evidence for and against the premise that treatment with APAP increases acceptance and adherence compared to fixed CPAP. In studies demonstrating an increase in adherence with APAP, there was similar improvement in measures of daytime sleepiness as with fixed CPAP treatment. Further studies are needed to determine if APAP can increase acceptance or adherence with positive pressure treatment in patients with OSA.

Adult↗
PubMed2002

Is morphine-induced sedation synonymous with analgesia during intravenous morphine titration?

BACKGROUND: Postoperative morphine titration frequently induces sedation. The assumption is made that patients sleep when their pain is relieved. Some patients complain of persistent pain when they awake. We studied the time-course of sedation and analgesia to understand the determinants of patients' sleep during morphine titration. METHODS: Seventy-three patients requiring morphine titration in a post-anaesthetic care unit after major surgery, were studied. Fifty-two patients slept (Sleep group) and 21 did not (Awake group). When a patient slept during titration, morphine was discontinued. Visual analogue pain scale (VAS), Ramsay score (RS), and the bispectral index (BIS) were recorded at the beginning of titration (STonset), at sleep onset (STsleep), then 5, 10, 20, and 30 min afterwards (ST4). RESULTS: In the Sleep group, mean (SD) RS increased from 1.7 (0.4) to 2.4 (0.6) (P<0.05 vs STonset) and BIS decreased from 95 (5.0) to 89.8 (10.2) between STonset and STsleep (P<0.05), RS remained stable thereafter. Conversely, RS and BIS remained unaltered in the Awake group. The reduction in VAS was comparable between groups (from 78 (17) to 39 (21), and from 64 (16) to 30.4 (11), respectively). Even though mean (SD) VAS was 39 (21) at ST4 in the Sleep group, 13 patients (25%) maintained a VAS above 50 mm. CONCLUSION: We observed dissociated effects of morphine on the time-course of sedation and analgesia with sedation occurring first, followed by analgesia. Therefore, morphine-induced sedation should not be considered as an indicator of an appropriate correct level of analgesia during i.v. morphine titration.

Adult↗
PubMed1992

[Functional liver disorder in relation to decreased titratable acidity of milk].

The internal environment of 17 dairy cows was observed by help of 23 variables of metabolic profile in blood and milk at lowered titratable acidity of milk (Tab. I) Average values of the observed variables were compared with reference values in a histogramme (Fig. 1). We calculated the statistical significance of differences of arithmetical means from reference average. Using correlation analysis we calculated the correlation coefficients for the observed variables. We represented the chosen correlation relations in correlogrammes (Fig. 2). We found significant correlation relations between AST and titratable acidity (degrees SH) (r = 0.791), AST and milk pH (r 0.617), AST and lactose (r = 0.69), AST and glucose (r = -0.56), blood pH and milk pH (r = -0.608), milk pH and lactose (r = -0.89). Mutual relations of titratable acidity with chosen variables of blood serum and milk were evaluated by help of regression coefficients, calculated for each parameter from the mathematical model (Fig. 3). The nearest relations were found for blood pH (regression coefficient /k/ kPH = -11.9), for AST (kAST = -3.1), for milk pH (k milk pH = -1.72) and for Mg (k Mg = -1.98). We also compared the recorded results of titratable acidity with theoretical values of titratable acidity calculated from the mathematical model (Tab. II). The differences between them were not statistically significant. It is evident from the results that the acid-base balance and functional liver condition influence the titratable acidity of milk.

Animals↗
PubMed1986

Acute titration and chronic follow-up with captopril in hypertension. A one-year safety profile on combination therapy with captopril and a diuretic.

The present study examines acute titration with captopril and chronic follow-up data on captopril and a diuretic in patients with all forms of hypertension. Captopril was initiated in those patients in whom previous antihypertensive agents either failed to control high blood pressure or produced adverse reactions. Acute titration was done in 88 patients in whom average diastolic blood pressure was equal to or more than 95 mm Hg. Initial titration dosage was decided on the basis of initial blood pressure recordings. During initial titration, 5 patients received 12.5 mg, 51 received 25 mg, 28 received 50 mg, and the remaining 4 received 100 mg of captopril. Post-captopril blood pressure data were normalized by using pre-captopril data as 100% for each patient. The blood pressure-lowering effect of captopril on both systolic and diastolic blood pressure in all 88 patients was statistically significant (p less than 0.05), within forty-five minutes of captopril administration irrespective of the doses. No adverse reactions were seen during the acute titration. After the initial titration, in all 88 patients a diuretic was added to obtain a synergistic effect. Eleven patients were dropped from the study, for they could not follow the requirements of the protocol. In 77 patients the data for a one-year safety profile with captopril and diuretic were available. There were no overall significant statistical changes in serial white blood cell count, serum potassium, and serum creatinine values in those 77 patients. In 31 patients the initial and maintenance dosage of captopril and the diuretic remained unaltered for one year. Post-captopril blood pressure and heart rate data were normalized, pre-captopril data being considered as 100% in those 31 patients. The blood pressure data following captopril and a diuretic therapy compared with the pre-captopril data were statistically significant (p less than 0.05) throughout the study period. However, no significant changes in heart rates were observed during the study period. In all other patients, diuretic therapy was continued throughout the study period. In 6 severely hypertensive patients, an additional beta-blocker was needed for further control of high blood pressure. In 3 severe hypertensives with renal failure, besides a diuretic and a beta-blocker, minoxidil was needed to normalize their high blood pressure. In 4 of 77 patients, verapamil was used for treatment of either vasospastic angina or paroxsysmal supraventricular arrhythmia.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic beta-Antagonists↗
PubMed1988

The pH dependence of red cell membrane transport of titratable anions studied by NMR spectroscopy.

The effects of varying extracellular pH on the rates of uptake of titratable anions by human erythrocytes under conditions of constant intracellular pH have been determined for a series of highly related anions, the phosphate "analogs." These compounds are simply substituted phosphorus oxyacids, differing in the number and acidity of titratable protons: phosphate (HPO4(2-), pKa 6.8); phosphite (HPO3(2-), pKa 6.4); hypophosphite (H2PO2-); methylphosphonate ((CH3)PO3(2-), pKa 7.4); dimethylphosphinate ((CH3)2PO2-); fluorophosphate [PO3F2-, pKa 4.7); and thiophosphate (HSPO3(2-), pKa 5.5). Suspensions of intact, Cl(-)-loaded erythrocytes (intracellular pH, 7.2) were incubated at 37 degrees C in isotonic buffers (pH 4-8) containing 60 mM phosphate analog for specified time intervals, whereupon influx was halted by the addition of 1 mM 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS), an inhibitor of anion exchange. The intracellular anion concentrations were determined from 31P or 19F nuclear magnetic resonance spectra from the erythrocyte suspensions. The influx rates for the titratable phosphate analogs exhibited bimodal pH dependence, reaching maximal levels at pH values that increased with increasing anion pK. This pH-dependent behavior is consistent with a transport channel that contains a titratable regulatory site which interacts with the translocated anion. Based upon the Henderson-Hasselbalch equation, the probability that a titratable anion will have an electric charge of equal magnitude to that of the titratable carrier is highest at a pH value exactly midway between the pK of the regulatory site and that of the anion. The pH maxima observed for the phosphate analogs indicate a pK for this site of 5.5 at 37 degrees C. Intracellular pH changes associated with influx indicated that transport of the "fast" anion phosphite is largely in monoionized form. Intracellular pH changes associated with transport of slow anions were predominantly determined by partial ionic equilibrium effects and did not indicate the ionization state of the transported anion.

Anions↗
PubMed1966

Automatic titration of plasma fatty acids by photocolorimetry.

A photocolorimeter for rapid automatic titration of free fatty acids is described. The solvents, absolute ethanol and hexane, form a single-phase titration mixture containing Nile blue indicator. The titrant, NaOH in 60% ethanol, is delivered by a motor-driven microsyringe; as alkali is added and the titration mixture turns pink, the intensity of light reaching a photocell through a 600 m micro interference filter increases. Increased current is generated until at a preselected number of microamperes a cut-off switch is activated which halts the drive motor. Titrations of FFA in the range 150-1500 micro eq/liter of palmitic acid standard are accomplished in approximately 1 min with a standard error of the mean of +/-1.3-6.5 micro eq/liter. The titration end point is independent of the operator. The solutions are stable and the daily titration blank and calibration remain constant. The procedure, therefore, is relatively simple and is quickly set up for routine determinations.

Autoanalysis↗
PubMed2003

Theory of pH-stat titration.

Innovative techniques are being studied to assess the activity of bioreactors and to improve the performance and operational stability of biological processes. Among these techniques, the pH-stat titration is applicable to any bioreaction involving pH variations. Up to now, the main application of the pH-stat titration has been for nitrification monitoring. In this article, we present a theoretical model of pH-stat titration, which predicts the response to any reaction involving the production or consumption of protons, hydroxyl ions, or inorganic carbon chemical species (CO(2), HCO(3)(-), CO(3)(=)). This model is a useful tool to understand pH-stat titrations, to define their applicability and limits, and to select the best experimental conditions for specific applications. Tests have been performed to compare experimental pH-stat titration rates in the presence of carbon dioxide and HCO(3)(-) producing reactions to the values predicted by the model and a very satisfying correspondence was found.

Bicarbonates↗
PubMed1977

pH-stat titration of aluminum hydroxide gel.

The pH-stat titration of aluminum hydroxide gel was evaluated and was affected by pH, temperature, concentration, and ionic strength. Control of these parameters resulted in a highly sensitive and reproducible in vitro antacid test. The utility of the pH-stat test was illustrated by monitoring the aging of several carbonate-containing aluminum hydroxide gels and by comparing the antacid properties as measured by the pH-stat titration, the acid-consuming capacity, the Rossett-Rice test, and the test proposed by the food and Drug Administration Drug Evaluation Panel. The pH-stat titration also was useful for relatively nonreactive aluminum hydroxide gels. The use of sodium fluoride as the reaction medium extended the capability of the pH-stat titration to monitor the aging of chloride-containing gels. The pH-stat titrigram was interpreted in terms of a previously published polymer model of the structure of a chloride-containing aluminum hydroxide gel. The acid reactivity of relatively nonreactive gel is believed to be due totally to the chemical neutralization of acid, because the milliequivalents of aluminum ion appearing in solution is the same as the milliequivalents of acid neutralized throughout the ph-stat titration.

Adsorption↗
PubMed1997

Prediction of titration properties of structures of a protein derived from molecular dynamics trajectories.

This paper explores the dependence of the molecular dynamics (MD) trajectory of a protein molecule on the titration state assigned to the molecule. Four 100-ps MD trajectories of bovine pancreatic trypsin inhibitor (BPTI) were generated, starting from two different structures, each of which was held in two different charge states. The two starting structures were the X-ray crystal structure and one of the solution structures determined by NMR, and the charge states differed only in the ionization state of N terminus. Although it is evident that the MD simulations were too short to sample fully the equilibrium distribution of structures in each case, standard Poisson-Boltzmann titration state analysis of the resulting configurations shows general agreement between the overall titration behavior of the protein and the charge state assumed during MD simulation: at pH 7, the total net charge of the protein resulting from the titration analysis is consistently lower for the protein with the N terminus assumed to be neutral than for the protein with the N terminus assumed to be charged. For most of the ionizable residues, the differences in the calculated pKaS among the four trajectories are statistically negligible and remain in good agreement with the data obtained by crystal structure titration and by experiment. The exceptions include the N terminus, which responds directly to the change of its imposed charge; the C terminus, which in the NMR structure interacts strongly with the former; and a few other residues (Arg 1, Glu 7, Tyr 35, and Arg 42) whose pKaS reflect the initial structure and the limited trajectory lengths. This study illustrates the importance of the careful assignment of protonation states at the start of MD simulations and points to the need for simulation methods that allow for the variation of the protonation state in the calculation of equilibrium properties.

Aprotinin↗
PubMed2005

Statistical criteria for the identification of protein active sites using Theoretical Microscopic Titration Curves.

Theoretical Microscopic Titration Curves (THEMATICS) may be used to identify chemically important residues in active sites of enzymes by characteristic deviations from the normal, sigmoidal Henderson-Hasselbalch titration behavior. Clusters of such deviant residues in physical proximity constitute reliable predictors of the location of the active site. Originally the residues with deviant predicted behavior were identified by human observation of the computed titration curves. However, it is preferable to select the unusual residues by mathematically well-defined criteria, in order to reduce the chance of error, eliminate any possible biases, and substantially speed up the selection process. Here we present some simple statistical tests that constitute such selection criteria. The first derivatives of the predicted titration curves resemble distribution functions and are normalized. The moments of these first derivative functions are computed. It is shown that the third and fourth moments, measures of asymmetry and kurtosis, respectively, are good measures of the deviations from normal behavior. Results are presented for 44 different enzymes. Detailed results are given for 4 enzymes with 4 different types of chemistry: arginine kinase from Limulus polyphemus (horseshoe crab); beta-lactamase from Escherichia coli; glutamate racemase from Aquifex pyrophilus; and 3-isopropylmalate dehydrogenase from Thiobacillus ferrooxidans. The relationship between the statistical measures of nonsigmoidal behavior in the predicted titration curves and the catalytic activity of the residue is discussed.

Amino Acid Isomerases↗
PubMed2002

Development and optimization of a real-time quantitative PCR-based method for the titration of AAV-2 vector stocks.

Despite the clinical application of adeno-associated virus (AAV) gene therapy, the titration of viral stocks has not yet been standardized. This complicates the comparison of viral stocks between laboratories. Functional titering of AAV is time-consuming, requires the manipulation of hazardous material, and often has a high degree of variability. We established an optimized real-time quantitative polymerase chain reaction (RQ-PCR) titration assay to determine viral titers and compared it with a functional green fluorescent protein (GFP)-based titration method. With a combination of improved lysis procedures and RQ-PCR protocols we could decrease the intraexperimental coefficient of variation (CV) from 0.24 +/- 0.03 to 0.042 +/- 0.004 and the interexperimental CV from 0.34 +/- 0.06 to 0.093 +/- 0.028 following functional and RQPCR-based titration, respectively. This low variability conforms to even the strictest quality standards required, for example, in clinical laboratories. The highly standardized titration by RQPCR described here will be especially advantageous for groups working on AAV-based gene therapy in a good manufacturing practice setting.

Base Sequence↗
PubMed1983

Comparison of the serial dilution indicator and intragastric titration methods for measurement of meal-stimulated gastric acid secretion in man.

Two in vivo methods that permit quantitation of gastric acid secretion immediately after the meal are currently in use: intragastric titration and the serial dilution indicator method. During intragastric titration, intragastric pH is artificially maintained at 5.5 to 7 by the continuous addition of alkali to the gastric contents, while during serial dilution the intragastric pH is permitted to seek its natural pH. This study compared gastric acid secretion and serum gastrin in response to a liquid protein meal measured by both techniques in 10 subjects. Mean (+/- SE) 3-hr acid outputs were almost identical (53.6 +/- 6.0 mmol/3 hr with intragastric titration and 52.0 +/- 8.5 mmol/3 hr with serial dilution indicator). Furthermore, 30 min secretory responses in individual subjects were highly correlated (r = 0.98 +/- 0.01, P less than 0.001). Also, in spite of intragastric pH being less than 1.5 by 90 min after the meal during the serial dilution method, total integrated serum gastrin concentrations after the meal were similar (intragastric titration = 20.6 +/- 7.3 ng min/ml versus serial dilution indicator = 23.5 +/- 9.8 ng min/ml) and individual 30-min gastrins during the two separate tests were highly correlated (r = 0.80 +/- 0.06, P less than 0.01). It is concluded that both meal-stimulated gastric acid secretion and serum gastrin concentrations as measured by intragastric titration and by the serial dilution indicator method produced similar results.

Dietary Proteins↗
PubMed1982

A microtiter test for detecting and titrating noncytopathogenic bovine viral diarrhea virus.

Bovine cells free of noncytopathogenic bovine viral diarrhea virus (NC-BVDV) treated with polyriboinosinic acid : polyribocytidylic acid (poly I:C) were protected against challenge with vesicular stomatitis virus (VSV), whereas NC-BVDV-infected cells treated with poly I:C were not protected against VSV. An assay based on the ability of NC-BVDV to inhibit poly I:C protection of cells against VSV was developed and is herein referred to as PINBA (poly I:C for NC-BVDV assay). Noncytopathogenic BVDV was titrated as cytopathogenic strains except that several days after infection with NC-BVDV, the cultures were treated with poly I:C and VSV. Titration endpoints were reached 24 hours later. PINBA was standardized for amount of VSV, time of addition of poly I:C, and time NC-BVDV had to be present to obtain stable titration endpoints. PINBA also was useful for titrating virus neutralizing antibodies. Compared with the fluorescent antibody test, PINBA was less subjective for detection of NC-BVDV. Compared with the interference test in which NC-BVDV infected cultures are challenged with a cytopathogenic strain of BVDV, PINBA was more reliable. The technique described herein is a simple and practical microtiter method for titrating NC-BVDV and virus neutralizing antibodies and for the presumptive detection of NC-BVDV.

Animals↗
PubMed1989

Intermittent shock titration task in the rhesus monkey and its validity as an analgesiometric procedure.

This study addressed issues concerning the validity of the shock titration paradigm by using focal, pulsed electrocutaneous stimulation and including unavoidable suprathreshold intensity stimuli among titratable, threshold intensity trials. In saline-treated monkeys, the distribution of response latencies on suprathreshold intensity trials, and the relationships between stimulus intensity and response latency, percent response or trial duration were consistent with those expected of painful stimuli. Morphine (0.3-3 mg/kg i.m.), meperidine (0.3-3 mg/kg i.m.) and pentazocine (1-6 mg/kg i.m.) each dose-dependently increased escape thresholds, but did not increase response latency on titratable trials. In contrast, diazepam (0.12-0.5 mg/kg i.m.) produced a dose-dependent increase in escape threshold and a significant increase in response latency on titratable trials. Sedative anxiolytics with muscle relaxant properties could therefore be distinguished from opioid analgesics. Morphine, meperidine, pentazocine and diazepam also produced a dose-dependent rightward shift in the frequency distribution of responses to suprathreshold stimuli at doses below those that significantly increased escape threshold. Thus, the antinociceptive effect of an opioid analgesic was detectable in the monkey in the clinically effective dose range. This paradigm permits analysis of drug effects at both escape threshold and suprathreshold intensities of noxious stimuli. The concomitant measurement of escape threshold and response latency on titratable trials with analysis of the frequency distribution of responses on suprathreshold trials yields a sensitive and discriminating analgesiometric procedure with potential application to rodent, as well as primate, species.

Analgesia↗
PubMed1988

A double-blind, placebo-controlled comparison of the efficacy of standard and individually titrated doses of theophylline in patients with chronic asthma.

Forty adult patients with chronic asthma completed a 3-month double-blind crossover study to compare the effect of sustained-release theophylline given both as a fixed 300 mg twice daily dose (standard) and an individually titrated dose (titrated) with placebo. Theophylline was given in addition to other usual therapy, inhaled bronchodilators, inhaled steroids and, in 12 patients, oral steroids. The 3-month period was preceded by a run-in phase to determine the dose of theophylline which each subject required to achieve peak serum levels of 12-20 mg/litre and trough levels of 8-12 mg/litre. Doses ranged from 300 mg to 700 mg twice daily. Twenty-one patients needed more than the standard dose to achieve satisfactory serum levels. Patients recorded daily peak flow rates and symptom scores and were seen at monthly intervals to measure lung function, check serum theophylline levels and change treatments, which were given in random order. FEV1 was significantly higher for the whole group after standard (2.11 litres) and titrated (2.15 litres) theophylline therapy than after placebo (1.89 litres), as was FVC, but in the large subgroup whose titrated dose was greater than the standard dose, the FEV1 only improved with the titrated dose. Peak flow measurements at home showed the same pattern. Patients taking oral steroids appeared to derive less benefit from theophylline than others. It is concluded that theophylline can usefully be added as a third-line drug in chronic asthma, but that since half the patients are likely only to benefit from a dose greater than 300 mg twice daily, while the other half may have high serum levels above this dose, it is essential to measure serum levels in order to use the drug effectively and safely.

Adult↗
PubMed1985

Brief report: evaluation of polymerized ragweed extracts by intradermal end point titration, RAST inhibition, and parallel line bioassay.

We have evaluated six polymerized ragweed extracts on the basis of RAST inhibition, parallel line bioassay, and intradermal end point titration. The results of the parallel line bioassay and intradermal end point titration are highly correlated (r = 0.995, df = 2, p less than 0.01). Both intradermal end point titration (r = 0.973, df = 4, p less than 0.01) and parallel line bioassay (r = 0.985, df = 2, p less than 0.05) are highly correlated with RAST inhibition. We have evaluated the utility of intradermal end point titration as a quantitative assay of relative allergenicity of polymerized extracts. The between assay reproducibility was derived by comparing a reference polymerized ragweed extract against itself. The 99% confidence limits of relative allergenicity were 53% to 188% when four assays were used. This compares favorably to the published 99% confidence limits of the parallel line bioassay 60% to 166% when three assays were used. Intradermal end point titration is highly reproducible, is highly correlated with RAST inhibition or parallel line bioassay, and thus is an appropriate bioassay of allergenic activity.

Allergens↗
PubMed1976

Differential hydrogen ion titrations of the histidine residues in Helix pomatia haemocyanin.

The properties of the histidine residues in Helix pomatia haemocyanin have been studied by differential hydrogen ion titrations. In oxy-and deoxyhaemocyanin 31 X 10(-5) histidine residues per g protein are titrated in contrast to 35 X 10(-5) residues in apohaemocyanin. The difference corresponds to a stoichiometry of one histidine residue per copper atom bound. Even in apohaemocyanin about 6 X 10(-5) histidine residues per g protein are not titrated in their normal pH region. In the presence of sufficient calcium to displace the dissociation completely out of the titration region, the titration curve of apohaemocyanin could be linarized according to the model of Linderstrom--Lang. In oxy-and deoxyhaemocyanin, however, a distinct deviation from linearity was found under the same conditions. In the absence of calcium the effect of the dissociation adds up to this deviation. The electrostatic interaction factors were determined for the protein at 0.1 M KC1 and for the dissociation products: halves and tenths at 1.0 M KC1. The electrostatic interaction factor for the wholes and the halves are much smaller than the values calculated from the Linderstrom--Lang equation, using the radius of the equivalent sphere either obtained from electron microscopy or from the partial specific volume. This probably due to solvent penetration. For the tenths at 1.0 M KC1, this effect is small.

Animals↗
PubMed2004

Effects of an anteriorly titrated mandibular position on awake airway and obstructive sleep apnea severity.

The objective of this study was to investigate whether a reduction of obstructive sleep apnea (OSA) severity was associated with significant upper airway (UA) changes after an anterior titration of the mandibular position. Eighteen OSA patients with a mean (SD) apnea hypopnea index (AHI) of 32.5 (12.3) were recruited. Baseline supine cephalometry was obtained before the initial insertion, and follow-up supine cephalometry was undertaken after titration with a titratable oral appliance in place. The mean AHI before treatment was significantly reduced to 9.7 (7.4) (P <.001) after titration. In 13 responders with AHI reduced to < or =15/h, a significant forward displacement of the anterior wall of the velopharynx (P <.05) was observed. In addition, there was a significant forward displacement of the posterior wall of the oropharynx and the hypopharynx (P <.05). In the 5 nonresponders, no significant changes in the position of the anterior and posterior wall were observed. There was no significant difference in the total amount of mandibular advancement between responders and nonresponders. We conclude that treatment success with oral appliance therapy appears to depend not only on anterior titration of the mandibular position to enlarge the UA, but also on the amount of change in the size of the UA in response to mandibular advancement.

Adult↗