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PubMed1989

Analysis of the molecular relatedness of four extended spectrum beta-lactamases (SHV-2, SHV-3, SHV-4 and SHV-5) by comparative protein titration curves.

Six beta-lactamases from Klebsiella pneumoniae, five of which (SHV-1, SHV-2, SHV-3, SHV-4 and SHV-5) were plasmid-encoded and one which (beta 1a GN 11-03) was chromosomally-encoded, were compared by analysis of their isoelectric points (pI), electrophoresis mobilities (MF) and titration curves or pH gradient electrophoresis. Four groups were defined by their pI and MF, namely SHV-1 and SHV-2 (pI = 7.6, MF approximately 14), SHV-3 and beta 1a GN 11-03 (pI = 7.0, MF approximately 20), SHV-4 (pI = 7.8 MF approximately 12) and SHV-5 (pI = 8.2, MF approximately 5). The titration curves of SHV-1 and SHV-2 enzymes on the one hand, and SHV-3 and beta 1a GN 11-03 on the other were completely superimposable for the whole of the pH gradient (3.5-10), indicating strongly similarity. Conservative amino-acid substitutions could account for the differences in the substrate spectra of the purified enzymes. The differences observed between the titration curves of the enzymes SHV-1/SHV-3, SHV-1/beta 1a GN 11-03, SHV-2/SHV-3 and SHV-5/SHV-4 pairs were consistent with the replacement of a basic amino-acid residue in the former enzyme of each pair by an acidic residue in the latter. Similarly, the titration curves of SHV-1/SHV-4 and of SHV-2/SHV-4 pairs may suggest the replacement of an acidic amino-acid in the former beta-lactamases by a neutral amino-acid in the latter of each pair. However, the presence of several self-cancelling or neutral substitutions is also possible. In contrast, when SHV-1 and TEM-1 (pI = 5.4 MF approximately 45) were titrated together, no structural relationship could be inferred.

Chromosomes, Bacterial↗
PubMed1978

Protonated polynucleotides structures - 22.CD study of the acid-base titration of poly(dG).poly(dC).

The acid-base titration (pH 8 --> pH 2.5 --> pH 8) of eleven mixing curve samples of the poly(dG) plus poly(dC) system has been performed in 0.15 M NaCl. Upon protonation, poly(dG).poly(dC) gives rise to an acid complex, in various amounts according to the origin of the sample. We have established that the hysteresis of the acid-base titration is due to the non-reversible formation of an acid complex, and the liberation of the homopolymers at the end of the acid titration and during the base titration: the homopolymer mixtures remain stable up to pH 7. A 1G:1C stoichiometry appears to be the most probable for the acid complex, a 1G:2C stoichiometry, as found in poly(C(+)).poly(I).poly(C) or poly(C(+)).poly(G).poly(C), cannot be rejected. In the course of this study, evidence has been found that the structural consequences of protonation could be similar for both double stranded poly(dG).poly(dC) and G-C rich DNA's: 1) protonation starts near pH 6, dissociation of the acid complex of poly(dG).poly(dC) and of protonated DNA take place at pH 3; 2) the CD spectrum computed for the acid polymer complex displays a positive peak at 255 nm as found in the acid spectra of DNA's; 3) double stranded poly(dG).poly(dC) embedded in triple-stranded poly(dG).poly(dG).poly(dC) should be in the A-form and appears to be prevented from the proton induced conformational change. The neutral triple stranded poly(dG).poly(dG).poly(dC) appears therefore responsible, although indirectly, for the complexity and variability of the acid titration of poly(dG).poly(dC) samples.

Circular Dichroism↗
PubMed1979

Calcium binding of troponin C. I. A potentiometric titration study.

Structural changes of troponin C on calcium binding were studied by hydrogen ion titration, circular dichroism, and fluorescence measurements. The potentiometric titration curves in the carboxyl region are shifted towards lower pH with calcium binding. The intrinsic pK of the carboxyl groups at the calcium binding sites decreases by 0.8 pK unit on calcium binding; on the other hand, magnesium ions have little effect on the intrinsic pK of the carboxyl groups. The intrinsic pK of the imidazole group is not affected by calcium binding. The value of w, an electrostatic interaction factor, is identical for calcium-free and calcium-bound troponin C and is about half of the value calculated assuming a compact sphere. The results of difference titration on the calcium binding indicate that the pH of troponin C solution increases on addition of CaCl2 up to 2 mol of Ca2+ per mol of troponin C and then decreases on further addition of CaCl2. The pH increase is depressed in the presence of MgCl2, in the low pH region, or at high ionic strength. The pH increase is also observed on addition of MgCl2. The ellipticity at 222 nm was measured under the same conditions as the difference titration measurements, and the relation between the pH change and the conformational change of troponin C on calcium binding is discussed based on the results obtained. The number of calcium binding sites and the binding constants estimated by analysis of these difference titration curves were in agreement with the results of Potter and Gergely (22). No magnesium binding site was observed. The tyrosine fluorescence measurements indicated that the binding site near tyrosine-109 is one of the high affinity sites.

Animals↗
PubMed1982

Fluorescence titrations of residue 59 and tyrosine in Kyn 59-RNase T1 and NFK 59-RNase T1.

Fluorescence titrations of kynurenine and tyrosine in Kyn 59-RNase T1 and NFK 59-RNase T1 were carried out by monitoring protein fluorescence through a pH change from 1.5 to 10.5. In the titration of kynurenine fluorescence at 455 nm, a few small but distinct quenching events occurred between pH 3.5 and 9.5. Three ionizable groups were found to be responsible for the individual steps of quenching observed. These groups are Glu 58 with pKa 4.6, His 40 or 92 with pKa 7.8 and Lys 41 with pKa 8.7. From this result, a subtle conformational change associated with the proton dissociation equilibria of Glu 58 and His 40 or 92 in the active site of Kyn 59-RNase T1 is suggested. The pH-titration behavior of tyrosine fluorescence in Kyn 59-RNase T1 was different from that of kynurenine fluorescence. Two acidic groups with pKa's 3.2 and 6.5 were detected as perturbants. In NFK 59-RNase T1, both N'-formylkynurenine and tyrosine showed almost the same fluorescence behavior during titration, which was characterized by two transitions between pH 3 and 8 in each titration curve. Two ionizable groups with pKa's 3.7-3.8 and 6.7-6.8 were determined. The role of the latter ionizable group is discussed in relation to the enzyme function of RNase T1. From the close similarity in structure and function between Kyn 59-RNase T1 and RNase T1, it is suggested that the same mechanism of conformational change linked to the ionization states of Glu 58 and His 40 or 92 exists in the native protein too.

Hydrogen-Ion Concentration↗
PubMed1998

Evaluation of the Healthdyne NightWatch system to titrate CPAP in the home.

Although a number of devices have been developed to monitor sleep and breathing in the home, there are few publications on methodologies by which CPAP can be titrated in the home setting. This study was conducted to determine the outcome of CPAP titration in the home using the Healthdyne NightWatch (NW) system. This home sleep-evaluation system was used to diagnose sleep apnea in 30 patients using a previously described methodology. These patients subsequently underwent CPAP titration in the home using the NW system, with modem technology allowing the transfer of data from the home to the laboratory. This group was compared with 30 patients who were diagnosed with sleep apnea using standard in-lab polysomnography and had CPAP titrated on a full night in the laboratory. Both groups were subsequently placed on CPAP at the appropriate pressure for 6-8 weeks, after which a full in-lab study was completed to assess CPAP efficacy at the prescribed pressure. Compliance was also determined using a pressure-activated monitor. No differences in any variable assessed could be found between the two groups. Mean compliance was 4.6 + 0.5 (SEM) and 4.3 + 0.5 hours of CPAP use per night for the home and in-lab groups respectively. Mean AHIs on the follow-up study were 7.4 + 1.2 and 7.6 + 1.6 events per hour for the home versus in-lab groups. Sleep stage distribution was also quite comparable between groups. As a result, this study suggests that sleep apnea can be diagnosed and CPAP titrated in the home with a similar outcome, at least at 6 to 8 weeks, to standard in-laboratory testing.

Adult↗
PubMed1997

Titration of volatile anesthetics using bispectral index facilitates recovery after ambulatory anesthesia.

BACKGROUND: The bispectral (BIS) index has previously been shown to be a quantifiable measure of the sedative and hypnotic effects of anesthetic drugs. This study was designed to assess the effect of BIS monitoring on the utilization of volatile anesthetics and their recovery profiles after ambulatory surgery. METHODS: Sixty consenting women undergoing outpatient laparoscopic tubal ligation procedures were randomly assigned to one of four treatment groups. After a standardized induction, anesthesia was maintained with either desflurane (Groups I and II) or sevoflurane (Groups III and IV) in combination with nitrous oxide, 65%, and fentanyl. In the control groups (Groups I and III), the anesthesiologists were blinded to the BIS value, and the volatile anesthetics were administered according to standard clinical practice. In Groups II and IV, the volatile anesthetics were titrated to maintain the BIS value at 60. The volatile anesthetic usage and the times from discontinuation of anesthesia to verbal response, orientation, and home-readiness were recorded. RESULTS: During the maintenance period, the BIS values were significantly lower in the control groups (mean, 42) compared with the BIS-titrated groups (mean, 60). The volatile anesthetic usage in the BIS-titrated groups was 30-38% lower (P < 0.05) compared with the control groups. Similarly, the times to verbal responsiveness were 30-55% shorter in the BIS-titrated (vs. control) groups. CONCLUSIONS: Titrating desflurane and sevoflurane using the BIS monitor decreased their utilization and contributed to a faster emergence from anesthesia in outpatients undergoing laparoscopic tubal ligation procedures.

Adult↗
PubMed2002

Stimulus titration and ECT dosing.

The seizure threshold to electroconvulsive therapy (ECT) is defined entirely by the duration of the induced seizure, is multidetermined, and varies enormously with a wide variety of patient and treatment factors, including especially the parameters of the ECT stimulus. No consistent relationship has ever been detected between the clinical antidepressant response to ECT and either the threshold or the duration of the induced seizure. The stimulus titration method for determining the seizure threshold (titration-threshold dosing) was the central research tool used to reverse years of dogma by proving that the induced seizure of ECT is not alone sufficient to explain the therapeutic properties of ECT, and that the interaction between dosage and treatment electrode placement is critical in this regard. In clinical use, however, titration-threshold dosing has proven less than fully effective in optimizing the stimulus dose for ECT-better results are consistently obtained with age-based or fixed high-dose methods. The lack of a direct correlation between either seizure threshold or duration and clinical ECT response is an irremediable flaw of the titration-threshold method as clinically applied. New approaches are now called for in which ECT stimulus dosage is set and adjusted ("titrated") according to the clinical antidepressant response of the patient or to measurable correlates thereof: maximum sustained electroencephalogram (EEG) ictal power, EEG postictal suppression, induced interictal EEG delta activity, peak heart rate, maximum sustained EEG coherence, and postictal EEG coherence reduction, all of which have been found by various investigators to be related to the clinical antidepressant response to ECT.

Depression↗
PubMed2004

Defining the standard of care in randomized controlled trials of titrated therapies.

PURPOSE OF REVIEW: To discuss the appropriate standard of care in randomized controlled trials of titrated therapies in critically ill patients. RECENT FINDINGS: The debate over the appropriate standard of care in randomized controlled trials was sparked by the Acute Respiratory Distress Syndrome Network trial of low tidal volume ventilation. In this trial, patients were randomized to either low or traditional tidal volume ventilation, and the investigators reported that low tidal volume ventilation significantly improved survival in patients with acute respiratory distress syndrome. However, it was argued that the control group used in this trial was not reflective of current practice patterns and that the improvement in survival may have been derived from patients in the control group being placed at increased risk. This debate forced intensivists to consider what defines an appropriate standard-of-care control group in randomized controlled trials of titrated therapies. If titrated therapies are to be studied safely, the mechanism behind the titration must be understood and incorporated into the control group. Failure to include a comparator group receiving current practice creates a study design that may jeopardize patient safety because there is no control group representing probable patient outcome outside of the trial. Additionally, randomizing patients to the extremes of a range of care without incorporation of a current practice control group prevents the investigators from making valid recommendations for changing current practice. SUMMARY: The incorporation of current practice patterns into randomized controlled trials of titrated therapies is essential for producing generalizable results and safeguarding patients.

Decision Making↗
PubMed1987

Oxytocin titration to achieve preset active contraction area values does not improve the outcome of induced labour.

The value of controlling oxytocin titration in induction of labour by a present uterine activity, assessed as active contraction area, was examined in a randomized study in 60 nulliparae and 54 multiparae. Each parity group was divided into two groups according to the cervical score (less than or equal to 5 and greater than 5) and within those four groups the women were randomly allocated to oxytocin titration against a present frequency of 6-7 uterine contractions every 15 min, or to a preset uterine activity equivalent to the 75th centile for spontaneous labour. The length of labour was slightly, but not significantly, longer in the frequency group. The mode of delivery, Apgar scores at 1 and 5 min and cord artery blood pH values were similar with the two modes of oxytocin titration. The mean maximum dose rate of oxytocin infusion was not significantly different except in the nulliparous group with a poor cervical score. The given mean total dose of oxytocin was similar in the different groups when controlled for parity and cervical score. The results suggest that oxytocin titration to achieve uterine activity values equivalent to the 75th centile of those observed in spontaneous labour does not confer any advantage compared with the traditional practice of titrating the oxytocin infusion to achieve a preset frequency of uterine contractions.

Apgar Score↗
PubMed2005

Defining the Q-site of Escherichia coli fumarate reductase by site-directed mutagenesis, fluorescence quench titrations and EPR spectroscopy.

We have used fluorescence quench titrations, EPR spectroscopy and steady-state kinetics to study the effects of site-directed mutants of FrdB, FrdC and FrdD on the proximal menaquinol (MQH(2)) binding site (Q(P)) of Escherichia coli fumarate reductase (FrdABCD) in cytoplasmic membrane preparations. Fluorescence quench (FQ) titrations with the fluorophore and MQH(2) analog 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) indicate that the Q(P) site is defined by residues from FrdB, FrdC and FrdD. In FQ titrations, wild-type FrdABCD binds HOQNO with an apparent K(d) of 2.5 nM, and the following mutations significantly increase this value: FrdB-T205H (K(d) = 39 nM); FrdB-V207C (K(d) = 20 nM); FrdC-E29L (K(d) = 25 nM); FrdC-W86R (no detectable binding); and FrdD-H80K (K(d) = 20 nM). In all titrations performed, data were fitted to a monophasic binding equation, indicating that no additional high-affinity HOQNO binding sites exist in FrdABCD. In all cases where HOQNO binding is detectable by FQ titration, it can also be observed by EPR spectroscopy. Steady-state kinetic studies of fumarate-dependent quinol oxidation indicate that there is a correlation between effects on HOQNO binding and effects on the observed K(m) and k(cat) values, except in the FrdC-E29L mutant, in which HOQNO binding is observed, but no enzyme turnover is detected. In this case, EPR studies indicate that the lack of activity arises because the enzyme can only remove one electron from reduced MQH(2), resulting in it being trapped in a form with a bound menasemiquinone radical anion. Overall, the data support a model for FrdABCD in which there is a single redox-active and dissociable Q-site.

Binding Sites↗
PubMed1975

Effect of the Fv-1 locus on the titration of murine leukemia viruses.

Titration of N- and B-tropic murine leukemia viruses on sensitive and resistant cell lines has been studied by direct XC plaque assay and infective center assay. The titration of cloned B-tropic virus by infective center assay on BALB/3T3 (Fv-1b/b) and NIH/3T3 (Fv-1n/n) cells gave one-hit patterns, with 100-fold less infected NIH/3T3 cells than BALB/3T3 cells. The titration of B-tropic virus on DBA/2 cells (Fv-1n/n) was also a one-hit. The titration of a one-hit curve, and there were about 100-fold less infected BALB/3T3 cells than NIH/3T3 cells. Comparable results were obtained by titrating the cloned N-tropic virus on congenic SIM (Fv-1n/n) and SIM.R (Fv-1b/b) cells or the Gross N-tropic virus on BALB/3T3 cells. Therefore, our data indicate that the multiple-hit phenomenon described previously may not be an essential part of the Fv-1 gene restriction.

Animals↗
PubMed2000

Comparison of two in-laboratory titration methods to determine effective pressure levels in patients with obstructive sleep apnoea.

BACKGROUND: Treatment of the sleep apnoea/hypopnoea syndrome with nasal continuous positive airway pressure (CPAP) conventionally requires a titration procedure in a sleep laboratory. The upper airway has a hysteresis phenomenon which accounts for a decrease in the effective positive pressure level once an initial effective pressure setting has been reached. The aim of this study was to quantify the difference in the initial and final effective pressure settings when the titration sleep study takes into account these possible changes in the effective pressure level. METHODS: Eighty five patients completed the study. During a titration sleep study the pressure was increased by 1 cm H2O in a stepwise fashion until obstructive respiratory events disappeared (effective pressure 1, Peff(1)). The pressure level was then decreased by increments of 1 cm H2O until breathing abnormalities reappeared. At this time pressure was re-increased by increments of 1 cm H(2)O to normalise breathing (Peff(2)). RESULTS: The mean (SD) value of Peff(1) was 9.5 (2.6) cm H2O. The pressure was then reduced during 0.5 (0.6) hours to reach the minimal pressure (7.0 (2.0) cm H2O). The pressure obtained after a downward titration had to be re-increased in 79 patients, the Peff(2) level being significantly lower than Peff(1) (8.9 (2.8) cm H2O, p = 0.0002), mean difference 0.6 (1.5) cm H2O (95% confidence interval 0.29 to 0.93). CONCLUSION: Attempts to decrease the positive pressure level during conventional determination of the effective pressure level allow a significant decrease in the pressure setting. This should be taken into account in each patient who requires an in-laboratory manual CPAP titration procedure.

Adult↗
PubMed1997

Automatic nasal continuous positive airway pressure titration in the laboratory: patient outcomes.

BACKGROUND: Manual titration of nasal continuous positive airway pressure (NCPAP) treatment for obstructive sleep apnoea (OSA) is time consuming and expensive. There are now "intelligent" NCPAP machines that try to find the ideal pressure for a patient by monitoring a combination of apnoeas, hypopnoeas, inspiratory flow limitation, and snoring. Although these machines usually find similar pressures to skilled technicians, it is not clear if their use in the sleep laboratory influences subsequent acceptance by patients. This study addresses this question. METHODS: One hundred and twenty two patients undergoing a trial of NCPAP were randomly allocated to either manual or automatic (Horizon, DeVilbiss) titration of pressure during their first night on NCPAP in a hospital sleep laboratory. The primary outcome (available on 112 patients) was the acceptance of NCPAP or otherwise six weeks following the initial titration night. Baseline indicators of severity were compared between the groups, as were the pressures selected and the subsequent improvement in the sleepiness of the patients. RESULTS: The initial severity of OSA was not significantly different in the two groups and the mean (SD) NCPAP pressures were similar (manual 8.7 (2.5) cm H2O, automatic 8.2 (2.1) cm H2O). The percentage of patients successfully established on CPAP at six weeks was 64% and 73% for the manual and automatic groups, respectively; 13% and 2%, respectively, in the manual and automatic groups had given up completely (p < 0.05), and there were about equal numbers (23% versus 25%) in the two groups who were still undecided. CONCLUSIONS: The substitution of automatic NCPAP titration for manual titration during the first night of NCPAP in patients with OSA does not reduce the number accepting the treatment at six weeks and may slightly improve it. This has important cost saving potential.

Humans↗
PubMed1983

Phosphorus-31 nuclear magnetic resonance pH titration studies of the phosphoproteins tropomyosin and glycogen phosphorylase a.

31P nuclear magnetic resonance (NMR), pH titration studies of the phosphoproteins tropomyosin and glycogen phosphorylase a (in the presence of the inhibitor glucose) show that the resonances for the phosphoserine regulatory sites shift with pH. Analysis of line widths indicates that both residues have considerable mobility. These results are in agreement with studies on similar phosphorylated sites on other proteins, leading us to propose that mobility is a general feature of such regulatory sites. pH titration studies on a series of model compounds have indicated that an empirical correlation exists between the Hill coefficient n (a measure of the cooperativity of the titration curve) and the presence of charged groups in the vicinity of the phosphoryl moiety. Moreover, these studies showed that within one class of similarly substituted phosphorus compounds the chemical shifts, the titration behaviour, and the pKa2 were comparable and allow for easy identification of these compounds. The pKa2 values for phosphoserine residues of proteins are in general slightly higher than those of phosphomonoester-containing small compounds. The titration data prompt our estimation that the maximal amount of energy associated with a salt linkage between a phosphoseryl side chain and a positively charged group is about 5 kcal (1 cal = 4.1868 J).

Animals↗
PubMed1990

Inhibition of gastric emptying by acids depends on pH, titratable acidity, and length of intestine exposed to acid.

Exposure of the small intestine to acid inhibits gastric emptying in a dose-related fashion that depends on titratable acidity and pH. Little information is available on the location of this inhibitory mechanism or on the relative contribution of titratable acidity and pH to this feedback control. We hypothesized that the dependence on titratable acidity is related to the length of the intestine exposed to acid and that the dependence on pH is related to the region of the intestine exposed to acid. To test these ideas, we studied 11 dogs with duodenal and jejunal fistulas. The inhibitory effects were tested when different lengths of the small intestine were exposed to test solutions of 0.03, 0.06, and 0.12 meq/ml titratable acidities. pH as an independent covariable was separated from titratable acidity by comparing the inhibition of gastric emptying of lactic acid (pH fixed to 2.4) to HCl (pH 0.96-1.6). Maximal inhibition of gastric emptying by both acids depended on acid exposure of a length of small intestine that was greater than 65 but less than or equal to 150 cm long. When acid was confined to the proximal 15 cm, increasing concentration of HCl (decreasing pH) resulted in increasing inhibition, but this effect was absent with increasing concentration of lactic acid (fixed pH). Inhibition was absent when 0.06 meq/ml HCl was infused into the intestine beyond the midintestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Coulometric acid-base titration in nanoliter samples with glass and antimony electrodes.

A modification of the coulometric acid-base titration method is described for the measurement of titratable acid and ammonium in nanoliter samples. The main components consist of a pH-seeking device and a miniaturized antimony electrode system capable of delivering OH- ions at a known rate. The modifications include use of a cup-shaped pH-sensitive glass-membrane electrode for monitoring pH changes during titration and a new electronic titration circuit consisting of a high-impedance differential electrometer, a constant-current source, and an electronic integrating circuit. Details regarding the construction of the components of the titration system and practical aspects of its use are also provided.

Acid-Base Equilibrium↗
PubMed1995

Time-course of stepwise CPAP titration. Behavior of respiratory and neurological variables.

Because successful medical treatment of obstructive sleep apnea/hypopnea syndrome (SAHS) depends on adequate CPAP treatment, we have analyzed in nine SAHS patients the behavior of respiratory and neurological parameters during a stepwise, polysomnography-controlled CPAP titration to achieve an optimal CPAP. Particularly, we have focused on which simple variable could predict the optimal CPAP pressure and could better define a distinctive optimal-suboptimal pattern. Main parameters analyzed through the CPAP titration procedure were respiratory events (apnea, hypopnea), the contour of inspiratory flow, the pleural pressure behavior, the thoraco-abdominal motion, oximetry, arousals, and sleep stage. During the CPAP titration we observed: (1) a rounded shape in the inspiratory flow contour was associated with the lowest esophageal pressure; (2) during stepwise increases in CPAP, almost all apnea events changed to hypopnea periods, followed by prolonged periods of limited inspiratory flow with still high esophageal pressure but without arousals (probably suboptimal CPAP); and (3) as CPAP reached suboptimal levels, sleep stage moved to deeper stages without arousals. We conclude that if during CPAP titration the end point is the disappearance of arousals, most patients with SAHS will still exhibit periods of high intrathoracic pressures with limited inspiratory flow. Alternatively, if the end point to be reached is the lowest esophageal pressure, higher CPAP levels will be needed. The contour of inspiratory flow appears as the simplest variable that best correlates with lowest esophageal pressure during CPAP titration.

Adult↗
PubMed2003

Can patients with obstructive sleep apnea titrate their own continuous positive airway pressure?

Manual continuous positive airway pressure (CPAP) titration in a sleep laboratory is costly and limits access for diagnostic studies. Many factors affect CPAP compliance, but education and support, rather than in-laboratory CPAP titration, appear to be pivotal. Self-adjustment of CPAP at home will provide equal or superior efficacy in the treatment of obstructive sleep apnea (OSA) as compared with in-laboratory titration. A randomized, single-blind, two-period crossover trial of CPAP treatment at the in-laboratory-determined optimal pressure versus at-home self-adjustment of CPAP (starting pressure based on prediction equation). Eighteen CPAP-naive patients (16 males, 50 +/- 15 years old, apnea hypopnea index 40 +/- 20) with a new diagnosis of OSA were tested. Testing was performed before and after CPAP treatment in each of two 5-week study limbs. CPAP, compliance with CPAP treatment, the Sleep Apnea Quality of Life Index, the Functional Outcomes of Sleep Questionnaire score, the Epworth sleepiness scale score, sleep architecture, sleep apnea severity, and maintenance of wakefulness tests were performed. Both modes of CPAP treatment significantly improved objective and subjective measures of OSA, but they did not differ in efficacy. Home self-titration of CPAP is as effective as in-laboratory manual titration in the management of patients with OSA.

Adult↗