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PubMed2000

Does the physiological success of CPAP titration predict clinical success?

Patients commencing continuous positive airway pressure therapy (CPAP) undergo overnight airway pressure titration in sleep centres to optimize breathing and sleep patterns. We tested the hypothesis that data from formal scoring of the sleep and breathing patterns observed at the best achievable pressure during titration can predict CPAP use and effectiveness, as our clinical experience suggested otherwise. The relationship between CPAP titration scores (apnoea/hypopnoea frequency, arousal frequency and sleep staging) and subsequent CPAP use was examined in 150 sleep apnoea/hypopnoea syndrome patients. One hundred patients were continuing CPAP therapy and 50 were randomly selected patients who had discontinued CPAP. Within the CPAP group, titration scores were compared with CPAP machine use, subjective daytime sleepiness and requirements for airway pressure adjustment. Respiratory irregularities and arousals during titration did not relate to outcome. Sleep-stage analysis revealed a weak relationship between more wakefulness during titration and CPAP discontinuation (P=0.02). There was a correlation between more prolonged Stage 4 sleep during titration and reduced sleepiness on established therapy (P=0.002), but this explained less than 12% of the variance. The absence of rapid eye movement sleep during titration was not associated with poorer outcomes. We conclude that routine scoring of breathing and sleep patterns observed during CPAP titration is of little clinical value, as the results do not predict outcome for individual patients. Satisfactory CPAP therapy may be established even if significant numbers of apnoeas/hypopnoeas or arousals are observed at the optimal pressure during titration.

Arousal↗
PubMed1978

The electronic state of heme in cytochrome oxidase II. Oxidation-reduction potential interactions and heme iron spin state behavior observed in reductive titrations.

Magnetic circular dichroism (MCD), electron paramagnetic resonance (EPR), and optical absorption spectroscopies have been used to monitor the concentrations of oxidized and reduced heme and copper during stoichiometric reductive titrations of purified beef heart cytochrome oxidase. The MCD data are deconvoluted to obtain the concentrations of reduced cytochromes a and a3 during the titrations; analysis of the EPR spectra provides complementary data on the concentrations of the EPR-detectable species. For the native enzyme in the absence of exogenous ligands, cytochromes a and a3 are reduced to approximately the same extent at all points in the titration. The reduction of the EPR-detectable copper, on the other hand, initially lags the reduction of the two cytochromes but in the final stages of the titration is completely reduced prior to either cytochrome a or a3. These non-Nernstian titration results are interpreted to indicate that the primary mode of heme-heme interaction in cytochrome oxidase involves shifts in oxidation-reduction potential for each of the two cytochromes such that a change in oxidation state for one of the hemes lowers the oxidation-reduction potential of the second heme by approximately 135 mV. In these titrations high spin species are detected which account for 0.25 spin/oxidase maximally. Evidence is presented to indicate that at least some of these signals can be attributed to cytochrome a3+ which has undergone a low-spin to high-spin state transition in the course of the titration. In the presence of carbon monoxide the oxidation-reduction properties of cytochromes a and a3 are markedly altered. The a32+. CO complex is fully formed prior to reduction of either cytochrome a3+ or the EPR-detectable copper. The g = 3 EPR signal attributed to cytochrome a3+ decreases as the MCD intensity of cytochrome a2+ increases; no significant high-spin intensity is observed at any intermediate stage of reduction. We interpret these Nernstian titration results to indicate that in the presence of ligands the oxidation-reduction potential of cytochrome a relative to cytochrome a3 is determined by the oxidation-reduction state of the stabilized cytochrome a3 ligand complex; if ligand binding occurs to reduced cytochrome a3 then cytochrome a titrates with a lower potential; cytochrome a titrates with a higher potential if oxidized cytochrome a3 is stabilized by ligand binding.

Animals↗
PubMed1989

A facile colorimetric protamine titration method.

On the basis of the reversible, competitive binding of protamine and azure A dye to heparin, a facile, colorimetric protamine titration method was developed. The method uses azure A dye as the titration indicator and has thus replaced the time-consuming clotting assay in the traditional protamine titration method with a rapid colorimetric assay. It offers the same accuracy in estimating the titration end point as the traditional titration method but allows the processing time to be significantly shortened. With the use of a premade diagnostic kit containing a fixed amount of azure A dye and various amounts of protamine, the titration end point can be determined in less than 5 minutes. This new colorimetric protamine titration method should provide clinicians with an easy and reliable means to accurately estimate the protamine dose required for heparin neutralization. It should also assist medical laboratories in preparing plasma samples that are free of heparin interference for routine coagulation tests. In a reverse manner, the colorimetric assay can also be used with a heparin titration procedure to quickly assess the heparin dose required for protamine reversal. For patients who have received overdoses of protamine, the availability of a facile heparin titration method may offer the prospect of exercising a heparin "back titration."

Azure Stains↗
PubMed1975

[Determination of sulphydryl and disulphide groups in proteins by amperometric titration. III. Investigation of the specifity of Ag+ ions for protein SH groups (author's transl)].

The specifity of Ag+ ions for protein SH groups has been questioned frequently, even though the amperometric titration with AgNO3 is one of the most common methods for the determination of SH groups in proteins. This is due to the fact, that the formation of silver complexes in the titration of cysteine causes a consumption of AgNO3 which is too high. In order to find out if this may be true in the case of proteins, in the present work select proteins with a well known content of SH and SS groups have been titrated amperometrically in tris buffer pH 7.4 with 0.001 M AgNO3. The proteins used were hemoglobin, bovine serum albumin, ovalbumin, lysozyme, pepsin, myoglobin, and cytochrome c. The direct and the indirect titrations of (a) native, (b) denatured, and (c) NaBH4 reduced proteins showed, that the expected consumption of AgNO3 was in no case exceeded. Therefore under the conditions used AgNO3 may be considered as a specific reagent for protein SH groups. High SH values as a result of the amperometric titration of proteins with silver nitrate, which have been published occasionally, may be due to incorrect estimation of the end point of the titration. The reducibility of SS groups depends on the kind of protein. Lysozyme and pepsin were already completely reduced at 23 degrees C, whereas bovine serum albumin needed 60 degrees C. The direct titration method was useful only in some cases for the detection of all SH groups originally present in the proteins or formed by reduction with NaBH4. On the other hand the indirect titration method gave maximum values, because the slowly reacting SH groups of proteins are also allowed to react and the resulting titration curves may be evaluated correctly.

Animals↗
PubMed2006

Does rapid dose titration affect the hepatic safety profile of Bosentan?

RATIONALE: Bosentan, a dual endothelin receptor antagonist, has proven efficacy in pulmonary hypertension. Due to an association with hepatic dysfunction, it is typically initiated at a sub-therapeutic dose for 4 weeks before titration to a therapeutic dose. At our institution some patients have undergone rapid titration, to potentially benefit from therapy earlier. This study assesses the impact of this practice on hepatic safety. METHOD: All patients initiated on bosentan therapy before April 2005 were included. Rapidly titrated patients achieved a therapeutic dose by 3 days, whereas standard titration patients were titrated at 4 weeks. All patients were monitored with monthly liver function tests. RESULTS: 149 patients commenced bosentan, of which 55 were rapidly titrated. At baseline, the two groups were similar in age, BMI, diagnosis, 6-min walking distance, alanine aminotransferase (ALT), cardiac index and pulmonary artery pressures. The rapid group had elevated right atrial pressures (9.7 mm Hg versus 7.4 mm Hg, p = 0.016) and worse WHO functional class (p = 0.008) and included less females (31% versus 69%, p = 0.024). The incidence of hepatic dysfunction in all patients was 12.8% at 12 months. There was no statistical difference in incidence between the rapid and standard groups (4% versus 11% at 3 months, p = 0.211 and 6% versus 15% at 12 months, p = 0.219). Of all patients on bosentan, hepatic dysfunction was most significantly associated with a higher baseline ALT (p = 0.021), female sex (p = 0.003) and underlying connective tissue disease (p = 0.025). Subgroup analysis suggested these factors were not confounders when comparing rapid and standard titration. CONCLUSIONS: Rapid and standard titration of bosentan resulted in similar hepatic safety profiles. Baseline ALT, female sex and the presence of connective tissue disease increased the risk of hepatic dysfunction independent of the titration method used.

Alanine Transaminase↗
PubMed1996

Complexometric determination of metal ions by microscopic diffusional titration.

Acid/base titrations of pico- and femtoliter microsamples have been performed previously using a diffusional microburet (DMB) for reagent delivery in a simple droplet-heptane system (Gratzl, M.; Yi, C. Anal. Chem. 1993, 65, 2085-2088). The lowest delivery rate achieved with a DMB was about 6 fmol/s, which would correspond to about a 1 microL/year volumetric flow rate with a hypothetical equivalent mechanical delivery scheme (Yi, C.; Gratzl, M. Anal. Chem. 1994, 66, 1976-1982). In this work, the feasibility of complexometric titrations in microscopic samples is explored. Stability of pH in the microdroplets required for different determinations and the effects of DMB shank geometry on titration characteristics are also studied. Diffusional microtitrations of Fe(III), Zn(II), and Cu(II) have been performed with EDTA. Xylenol orange and Eriochrome Black T provide clear color changes at the end point of the respective titrations, despite the microscopic size of the samples (between 16 and 1570 pL, corresponding to diameters between 30 and 144 microns). Random errors of the determinations relative to full scale were 6.6% for Fe(III), 5.8% for Cu(II), and 7.9% for Zn(II). The pH required for EDTA titrations of the individual metal ions stays stable in the acidic range. This makes the microscopic titration of a number of metal ions, such as Fe(III), Fe(II), Cu(II), and Pb(II), feasible in a simple droplet-heptane system without any modification. With a higher density of strongly alkaline buffer droplets (about 100 droplets/mm2) sprayed on the bottom of the Petri dish, or by flushing N2 above the heptane, the microscopic samples can also be kept alkaline despite ambient CO2 present. In this way, Zn(II) can also be titrated in microdroplets, requiring a pH around 10. This work renders it possible to perform a variety of complexometric titrations and other chemical manipulations in microdroplets even if they need to be kept alkaline. Similar titrations in single biological cells to assess intracellular buffer capacities of different metal ions, such as Ca(II) and Mg(II), are underway.

Diffusion↗
PubMed2006

Assessment of two theoretical methods to estimate potentiometric titration curves of peptides: comparison with experiment.

We compared the ability of two theoretical methods of pH-dependent conformational calculations to reproduce experimental potentiometric titration curves of two models of peptides: Ac-K5-NHMe in 95% methanol (MeOH)/5% water mixture and Ac-XX(A)7OO-NH2 (XAO) (where X is diaminobutyric acid, A is alanine, and O is ornithine) in water, methanol (MeOH), and dimethyl sulfoxide (DMSO), respectively. The titration curve of the former was taken from the literature, and the curve of the latter was determined in this work. The first theoretical method involves a conformational search using the electrostatically driven Monte Carlo (EDMC) method with a low-cost energy function (ECEPP/3 plus the SRFOPT surface-solvation model, assumming that all titratable groups are uncharged) and subsequent reevaluation of the free energy at a given pH with the Poisson-Boltzmann equation, considering variable protonation states. In the second procedure, molecular dynamics (MD) simulations are run with the AMBER force field and the generalized Born model of electrostatic solvation, and the protonation states are sampled during constant-pH MD runs. In all three solvents, the first pKa of XAO is strongly downshifted compared to the value for the reference compounds (ethylamine and propylamine, respectively); the water and methanol curves have one, and the DMSO curve has two jumps characteristic of remarkable differences in the dissociation constants of acidic groups. The predicted titration curves of Ac-K5-NHMe are in good agreement with the experimental ones; better agreement is achieved with the MD-based method. The titration curves of XAO in methanol and DMSO, calculated using the MD-based approach, trace the shape of the experimental curves, reproducing the pH jump, while those calculated with the EDMC-based approach and the titration curve in water calculated using the MD-based approach have smooth shapes characteristic of the titration of weak multifunctional acids with small differences between the dissociation constants. Nevertheless, quantitative agreement between theoretically predicted and experimental titration curves is not achieved in all three solvents even with the MD-based approach, which is manifested by a smaller pH range of the calculated titration curves with respect to the experimental curves. The poorer agreement obtained for water than for the nonaqueous solvents suggests a significant role of specific solvation in water, which cannot be accounted for by the mean-field solvation models.

Algorithms↗
PubMed2001

Stimulus dose titration for electroconvulsive therapy.

UNLABELLED: Stimulus dose titration for electroconvulsive therapy (ECT), the method to determine seizure threshold accurately, has not been commonly practiced. We describe our early experience of dose titration in 22 Chinese patients and compare seizure thresholds measured by dose titration with values predicted by the formula-based 'half-age' METHOD: Seizure thresholds, as measured by dose titration, varied fourfold among our sample and the average value was 105.5 mC or 16.7 J. At the titration session, 27% of patients had seizures after a single stimulation and 37% had seizures after two stimulations. Only one patient required four stimulations to induce a seizure. No patient had significant adverse events associated with the dose titration procedure. The 'half-age' method in average overestimated seizure thresholds by 44% when compared with that measured by dose titration and in 23% of our sample, the overestimation was more than 100%. The pros and cons of dose titration and 'half-age' prediction method will be discussed. Our early experience suggests that dose titration could be performed in the majority of patients receiving ECT.

Adult↗
PubMed1976

Redox titration of fluorescence yield of photosystem II.

The variable fluorescence yield of photosystem II is dependent on the redox state of the fluorescence quencher molecule or the primary electron acceptor of the system. We have carried out redox titrations of fluorescence yield of a photochemically active photosystem-II reaction-center particle and have measured the redox potential of the photosystem-II primary acceptor.During reductive titrations using dithionite as the reductant, only a single quenching transition was observed. For instance, at pH 7.0, the midpoint potential of the fluorescence transition is -325 mV, and those at a pH between 6.0 and 7.5 are consistent with a pH dependence of about 60 mV/pH unit. At a given pH, the midpoint potential of the transition closely corresponds to that of the most negative transition previously measured in unfractionated chloroplasts (both by chemical reductive titration). Oxidative titrations using ferricyanide as the oxidant yielded hysteresis in the titration curves.Similar changes in fluorescence yield were observed in redox titrations by electrochemical reduction or oxidation. Electrochemical reductive and oxidative titrations yielded reversible transitions, contrary to the hysteresis observed during chemical oxidative titration. From coulometric-titration data, we have estimated that most likely one electron is involved in the redox transition of the fluorescence-quencher or primary-electron-acceptor molecule of photosystem II. These findings are consistent with the current proposal that a membrane-bound plastoquinone functions as the primary acceptor of photosystem II.

Journal Article↗
PubMed2006

The pH change after HCl titration into resting and stimulated saliva for a buffering capacity test.

BACKGROUND: Saliva collection can provide clinical information about individual patients. However, a correlation between ranking buffering capacity using resting and stimulated saliva is still unknown. The aim of this study was to evaluate the pH change after HCl titration into resting and stimulated saliva for a salivary buffering capacity test. METHODS: Resting and stimulated saliva (by chewing paraffin wax) were collected from 80 patients. After the pH of both saliva samples was measured using a hand-held pH meter, the saliva samples were titrated with 0.1N HCl to evaluate the buffering capacity. Correlations of ranking buffering capacity (high, medium, low) between stimulated saliva and resting saliva with 30 microL HCl titration and between stimulated saliva and resting saliva with 40 microL HCl titration were statistically analysed by Spearman Rank Correlation Test (p < 0.05). RESULTS: At 50 microL HCl titration, stimulated saliva buffering capacities were ranked into high (above pH 5.5), medium (pH from 5.5 to 4.5) and low (below pH 4.5). At 30-40 microL HCl titration, the resting saliva buffering capacities were ranked into the same categories. Spearman Rank Correlation indicated significant positive coefficients for the stimulated saliva and resting saliva buffering capacity at 30 microL titration and the stimulated saliva and resting saliva at 40 microL titration. CONCLUSION: Stimulated saliva is more resistant to variation in pH change during HCI titration than resting saliva. Stimulated saliva sampling is a good method to determine buffering capacity during a comprehensive oral health assessment.

Adolescent↗
PubMed1996

Automated continuous positive airway pressure titration for obstructive sleep apnea syndrome.

This study tested the effectiveness of the AutoSet self-titrating nasal continuous positive airway pressure (nCPAP) system in treating obstructive sleep apnea (OSA), and choosing a suitable pressure for subsequent conventional fixed-pressure nCPAP therapy. Twenty-one adult men with untreated OSA were studied with full polysomnography on each of four nights: diagnostic, manual and AutoSet nCPAP titration (in random order), and conventional fixed-pressure nCPAP at the pressure recommended by the AutoSet titration. Titration was satisfactorily performed in 20 of 21 subjects. Severe mask leak prevented automated titration in one subject and caused transient unnecessary increases in pressure in three subjects. In the 20 subjects, respiratory disturbance index (RDI) was 60.3 +/- 5.7 events/h (mean +/- SEM) on the diagnostic night. RDI was lower with manual titration (10.1 +/- 3.0, p < 0.001), and lower still with Autoset (2.8 +/- 0.9, p < 0.01) and fixed pressure (2.5 +/- 0.7, p = ns versus AutoSet) nCPAP. There were similar changes in the arousal index, which was 52.7 +/- 4.6 events/h on the diagnostic night, 14.2 +/- 2.4 with manual titration and 8.9 +/- 0.9 with AutoSet titration, and 9.5 +/- 1.0 on the night of conventional fixed-pressure CPAP (p < 0.001 versus diagnostic). We conclude that the AutoSet system is suitable for automated nCPAP pressure titration.

Adult↗
PubMed2001

Topiramate titration and tolerability.

OBJECTIVE: To evaluate the tolerability and efficacy of two titration rates for topiramate initiated as adjunctive therapy in adults with partial-onset seizures, with or without secondary generalization, in a multicenter, double-blindtrial. METHODS: After a two-week baseline phase, 188 patients were randomized to either a 50/50 titration schedule (initial dosage 50 mg/d increased in 50-mg/d increments at weekly intervals; n = 95) or to a 100/200 titration schedule (initial dosage 100 mg/d increased by 100-200 mg/d at weekly intervals; n = 93). The maximum dosage of 400 mg/d was therefore achieved in eight weeks or three weeks, respectively. RESULTS: Compared with the 100/200 titration rate, the 50/50 titration rate significantly reduced the cumulative incidence of treatment-emergent adverse events (TEAEs) leading to changes in topiramate therapy (ie., dosage reductions, interruptions or discontinuations of therapy) (p = 0.048) and significantly reduced treatment interruptions or withdrawals due to TEAEs (p = 0.040). Mild or moderate effects involving the central nervous system were the most frequent adverse events. At the final visit, therapeutic responses were comparable in the 50/50 and 100/200 titration groups: median percent seizure reduction was 42% vs. 33%, proportion of patients with 250% seizure reduction was 42% vs. 38%, and proportion of patients with no seizures during double-blind treatment was 14% vs. 10%, respectively. Seizure frequency was substantially reduced from baseline during topiramate titration. At day 22, with the 50/50 titration group receiving 150 mg/d and the 100/200 titration group receiving 400 mg/d, the mean percent seizure reduction was 51% and 54%, respectively. CONCLUSIONS: Gradual initiation of topiramate therapy can significantly enhance patient tolerability without delaying therapeutic response.

Adolescent↗
PubMed1998

Daytime CPAP titration: a viable alternative for patients with severe obstructive sleep apnea.

OBJECTIVE: Continuous positive airway pressure (CPAP) is the treatment of choice for patients diagnosed with severe obstructive sleep apnea (OSA). The implementation of CPAP therapy has traditionally been based on full-night titration studies or split-night protocols. This study compared a group of patients who received a regular nocturnal CPAP titration with patients who received a daytime CPAP titration. The objective of the study was to determine if daytime CPAP titration is a viable alternative for the implementation of CPAP treatment in patients with severe OSA. STUDY DESIGN: Fourteen patients (13 men and one woman) received a daytime CPAP titration (day group). The day group was matched to 18 patients (17 men and one woman) who were titrated under a full-night regular nocturnal study (night group). Eligible patients were those with severe OSA (respiratory event index > 40). The groups were matched by age, sex, and body mass index. RESULTS: Daytime and nocturnal CPAP titration studies yielded sufficient amounts of rapid eye movement (REM) and non-REM sleep to help determine CPAP settings. Importantly, the diurnal and nocturnal CPAP titrations resulted in comparable therapeutic pressures as well as comparable resolution of sleep-disordered breathing. After 1 week of treatment, the groups exhibited similar CPAP use and comparable improvements in subjective sleepiness as indicated by their increase in sleep/wake activity inventory scores. CONCLUSIONS: Daytime CPAP titration studies may be a viable alternative for the efficient and expedient implementation of CPAP therapy among some patients with severe OSA.

Adult↗
PubMed2004

[Unattended automated titration to determine therapeutic continuous positive airway pressure in patients with obstructive sleep apnea].

Recently, devices which use a new technology that automatically titrates positive airway pressure have become available. Such devices continually adjust the pressure to maintain airway patency. In this paper, unattended automated titration to determine the therapeutic continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea was evaluated to ascertain of it was a feasible titration to determine the therapeutic CPAP. Thirty patients participated in this study with obstructive sleep apnea syndrome defined by an apnea hypopnea index > 20/h. Automated titration during full polysomnography was performed in the hospital using auto CPAP devices (Autoset T, RESMED Co, Australia). During titration, there was no direct supervision by a technician. The titration method was as follows. Data obtained during the use of auto CPAP devices and polysomnography were used to provide a fixed single pressure for subsequent treatment. After determining the therapeutic continuous positive airway pressure, the efficacy of the patient's CPAP device was reconfirmed during full polysomnography. The results were, 1) Proper fixed single therapeutic pressure could be determined with this unattended automated titration, consequently apnea and sleep structure could be improved (Total sleep time, Sleep efficiency, %Stage 3 + 4, Apnea index, Apnea hypopnea index, Arousal index, Lowest SpO2, and Duration of SpO2 less than 90% were improved statistically (p < 0.05)). 2) The 95th percentile airway pressure of the auto CPAP device should be applied for the therapeutic pressure. 3) Automated titration during full polysomnography should be performed using auto CPAP devices. 4) After determining the therapeutic CPAP, the efficacy of the patient's CPAP device should be reconfirmed during full polysomnography. 5) This method of titration was useful at the institution without attendant technician intervention.

Automation↗
PubMed1979

Comparison of acid secretion rates measured by gastric aspiration and by in vivo intragastric titration in healthy human subjects.

In nine healthy subjects acid secretion rates, measured first by gastric aspiration and then by in vivo intragastric titration to pH 5, were compared. In vivo intragastric titration was initiated by instilling 50, 100, or 700 ml saline (pH 5) into the stomach, followed by a continuous intragastric saline infusion at 3.3 ml/min. Irrespective of the volume of saline used to initiate in vivo intragastric titration, acid secretion rates during titration were two to three times greater than secretion rates during gastric aspiration (P less than 0.005). This difference was not due to transpyloric acid losses during aspiration, since such losses were corrected for by nonabsorbable marker recovery; nor was the difference due to a higher intragastric pH during in vivo titration, since significant differences in acid secretion rates between aspiration and titration persisted when in vivo titration was performed at an acid pH. These findings suggest that in vivo intragastric titration leads to higher measured acid secretory rates than gastric aspiration because the titration method is associated with gastric distention and even small degrees of gastric distention stimulate gastric acid secretion.

Adult↗
PubMed1983

Optimization of a novel two-phase potentiometric titration method of barbiturates with mercury (II). Part II: Experimental evaluation.

A two-phase potentiometric titration procedure of barbiturates with mercury(II) was developed. The composition of the formed mercury-barbiturate complexes was elucidated by infrared spectrometry. In the new titration procedure the barbituric acid derivative is dissolved in an aqueous borate buffer. An organic phase consisting of chloroform and benzyl alcohol is added, and the vigorously stirred contents of the titration vessel are titrated by a mercury(II) nitrate solution. In the potentiometric determination of the end-point a rotating mercury electrode is used as an indicator electrode that also serves as an efficient stirrer. The two-phase procedure was compared with a one-phase mercurimetric potentiometric titration in borate buffer and with the potentiometric titration by sodium hydroxide in an ethanol-water solution. The proposed two-phase procedure is superior to both methods because lower concentrations of barbiturates (10(-3) - 10(-4) M) can be determined successfully. The one-phase procedure suffers from systematic errors, while the titration with sodium hydroxide is less precise at concentration levels of the barbiturates prevailing in content uniformity studies. By the two-phase procedure the direct titration of phenobarbital and mephobarbital in a dry mix of tablet excipients was possible with a relative standard deviation smaller than 1.5 percent.

Barbital↗
PubMed2005

The use of a predicted CPAP equation improves CPAP titration success.

Titration of continuous positive airway pressure (CPAP) is performed to determine the CPAP setting to prescribe for an individual patient. A prediction equation has been published that could be used to improve the success rate of CPAP titrations. The goals of this study were: (1) to test the hypothesis that the use of the prediction equation would achieve a higher rate of successful CPAP titrations; (2) to validate the equation as an accurate predictor of the prescribed CPAP setting and determine the factors that influence the accuracy of the prediction equation. A total of 224 patients underwent CPAP titration prior to using the equation, with a starting pressure of 5 cm H(2)O. A total of 192 patients underwent CPAP titration using the equation-predicted CPAP level as the starting pressure (median starting pressure of 8 cm H(2)O [interquartile range 7, 10 cm H(2)O]). The percentage of successful studies, as defined by a 50% decrease in the apnea-hypopnea index (AHI) and a final AHI < or =10 cm H(2)O, increased from 50% to 68% (p<0.001), while the number of patients who were prescribed a CPAP level that had not been tested decreased from 22% to 5% (p<0.001). The equation was not accurate in predicting the prescribed level of CPAP, with only 30.8% of the patients with a prescribed pressure < or =3 cm H(2)O of the predicted pressure. Female gender was the only predictor of a prescribed pressure < or =3 cm H(2)O from the predicted pressure (odds ratio 3.45, 95% confidence intervals 1.67, 7.13, p<0.001). A CPAP prediction equation modestly increases the rate of successful CPAP titrations by increasing the starting pressure of the titration. The equation does not accurately predict the prescribed CPAP level, reaffirming the need for a titration study to determine the optimal prescribed level in a given patient.

Body Mass Index↗
PubMed2006

Rapid titration of carvedilol in patients with congestive heart failure: a randomized trial of automated telemedicine versus frequent outpatient clinic visits.

BACKGROUND: Because of potential side effects and logistical difficulty of titrating medications, outpatients with congestive heart failure rarely receive appropriate doses of carvedilol or other beta-blockers. To address these obstacles, we studied if an automated telemedicine system named TeleWatch (TW) could facilitate carvedilol titration in outpatients with left ventricular systolic dysfunction. METHODS: Forty-nine patients with New York Heart Association class II and III left ventricular systolic dysfunction, who were tolerating appropriate afterload-reducing therapy and not receiving beta-blockers, were enrolled into a 3-month study. Patients were randomized to have clinic-only (CO) (n = 24) carvedilol titration or titrations which combined clinic visits with TW monitoring (n = 25). All patients were seen in clinic biweekly, and those in the TW group were remotely monitored daily. Using a predefined algorithm, patients in the CO and TW groups were eligible for carvedilol titration on a biweekly or weekly basis, respectively, by physicians blinded to group assignment. RESULTS: There was no statistical difference in the mean final daily dose of carvedilol between the CO and TW groups (39.4 vs 36.2 mg/d, P = .52). Because remote telemedicine titrations were as successful as titrations in the clinic, the time to reach the final dose of carvedilol was significantly shorter in the TW group (33.6 vs 63.7 days, P < .0001). There were 5 serious adverse events in the study, 4 of which were in the TW group (P = .29); however, TW prospectively detected 2 adverse events. CONCLUSIONS: Remote monitoring with an automated telemedicine system can successfully facilitate titration of carvedilol in outpatients with New York Heart Association class II and III congestive heart failure.

Adrenergic beta-Antagonists↗