Validating respiratory index of auto-titrating positive airway pressure device with polysomnography

Purpose

Positive airway pressure (PAP) devices have been widely used as the first line of treatment in obstructive sleep apnea (OSA). Most advanced PAP devices support the estimation of respiratory index (RI) using the patient’s mask airflow. In addition to the compliance factor for PAP device use, which is important for monitoring patient sleep health, RI is also becoming important for monitoring. However, there are few reports that validate RI of a PAP device with polysomnography.

Methods

Between January 2015 and December 2017, 50 participants were enrolled who were diagnosed with OSA and prescribed auto-titration PAP (APAP) devices. The RIs of participants were measured at night using APAP devices, concurrently with electroencephalography, respiratory inductance plethysmography sensors, and other polysomnographic sensors in a sleep laboratory. The respiratory-related data of APAP were prospectively analyzed with the manually scored polysomnographic data.

Results

The apnea-hypopnea index and apnea index showed a statistically close relationship between the auto-scored respiratory data from the APAP device and the manually scored respiratory data from polysomnographic sensors. Obstructive apnea and central apnea indices showed relatively low correlations. The differences between the auto-scored RI and manually scored RI were influenced by BMI, waist circumference, weight, oxygen saturation, and respiratory distress indices of diagnostic polysomnographic factors.

Conclusions

The RIs of APAP devices have a tendency to be underestimated or mismatched when compared with polysomnography. Sleep specialists are advised to consider additional anthropometric and diagnostic factors to account for these differences during PAP treatment.

     

Impact of aminophylline on the pharmacodynamics of propofol in beagle dogs

This study aimed to characterize pharmacodynamic interaction between propofol and aminophylline. Nine beagle dogs were randomly allocated at the propofol rates of 0.75 (group A), 1.00 (group B), and 1.25 (group C) mg/kg/min. During period 1, propofol only was infused, while during period 2, aminophylline only, at the rate of 0.69 (group A), 1.37 (group B), and 2.62 (group C) mg/kg/h. During periods 3–5, the two drugs were co-administered. The aminophylline infusion rate was 0.69 (period 3), 1.37 (period 4), and 2.62 (period 5) mg/kg/h. The aminophylline was infused from 0 to 30 h, and the propofol was infused at 24 h for 20 min. Blood samples and electroencephalograms were obtained at preset intervals. In the linear regression between log-transformed doses of aminophylline and AUC _inf , the slope was 0.6976 (95 % CI 0.5242–0.8710). Pharmacokinetics of aminophylline was best described by a one-compartment, with enzyme auto-induction, model. Pharmacokinetics and pharmacodynamics of propofol were best described by a three-compartment model and a sigmoid E _max model, respectively. Pharmacodynamic parameter estimates of propofol were: k _e0 = 0.805/min, E ₀ = 0.76, E _max  = 0.398, Ce _{50 na}  = 2.38 μg/mL (without aminophylline-exposure), Ce _{50 wa}  = 4.49 μg/mL (with aminophylline-exposure), and γ = 2.21. Propofol becomes less potent when exposed to aminophylline. Pharmacodynamic antagonistic interaction of aminophylline with propofol sedation, may occur, not in a dose-dependent manner, but in an all-or-none response.     

Pain on injection with microemulsion propofol

AIMS

To evaluate the incidence and severity of injection pain caused by microemulsion propofol and lipid emulsion propofol in relation to plasma bradykinin generation and aqueous free propofol concentrations.

METHODS

Injection pain was evaluated in 147 patients. Aqueous free propofol concentrations in each formulation, and in formulation mixtures containing agents that reduce propofol-induced pain, were measured by high-performance liquid chromatography. Plasma bradykinin concentrations in both formulations and in their components mixed with blood sampled from six volunteers were measured by radioimmunoassays. Injection pain caused by 8% polyethylene glycol 660 hydroxystearate (PEG660 HS) was evaluated in another 10 volunteers.

RESULTS

The incidence of injection pain [visual analogue scale (VAS) >30 mm] caused by microemulsion and lipid emulsion propofol was 69.7 and 42.3% (P < 0.001), respectively. The median VAS scores for microemulsion and lipid emulsion propofol were 59 and 24 mm, respectively (95% confidence interval for the difference 12.5, 40.0). The aqueous free propofol concentration of microemulsion propofol was seven times higher than that of lipid emulsion propofol. Agents that reduce injection pain did not affect aqueous free propofol concentrations. Microemulsion propofol and 8% PEG660 HS enhanced plasma bradykinin generation, whereas lipid emulsion propofol and lipid solvent did not. PEG660 HS did not cause injection pain.

CONCLUSIONS

Higher aqueous free propofol concentrations of microemulsion propofol produce more frequent and severe pain. The plasma kallikrein–kinin system may not be involved, and the agents that reduce injection pain may not act by decreasing aqueous free propofol concentrations.     

Validity analysis of respiratory events of polysomnography using a plethysmography chest and abdominal belt

Purpose

Respiratory inductive plethysmography (RIP) is recommended as an alternative respiratory sensor for the identification of each apnea and hypopnea event in polysomnography. Using this sensor, the cumulative RIP results from the chest and abdomen (RIP sum) and time-derived results of the RIP sum (RIP flow) are calculated to track respiratory flow. However, the effectiveness of this sensor and the calculated respiratory results is still unclear, and validation studies for the scoring of respiratory events in polysomnography are rare.

Methods

Two hundred subjects were selected according to the severity of obstructive sleep apnea. A sleep specialist re-evaluated the respiratory events based on RIP flow data in a single-blind study. Statistical analysis was conducted with paired respiratory events scored in each of the RIP flow and polysomnography datasets.

Results

All respiratory events scored from the RIP flow were strongly correlated with those identified with standard sensors of polysomnography, regardless of disease severity. Most of the respiratory parameters from RIP flow trended toward underestimation. The RIP flow obtained from the alternative RIP sensor was appropriate for the diagnosis of obstructive sleep apnea based on a receiver operating characteristic curve.

Conclusions

Scored respiratory events from RIP flow data effectively reflected the respiratory flow and statistically correlated with the results from standard polysomnography sensors. Therefore, analyzing RIP flow utilizing an RIP sensor is considered a reliable method for respiratory event scoring.

     

Anti-Arthritic and Analgesic Effect of NDI10218, a Standardized Extract of Terminalia chebula,on Arthritis and Pain Model

The fruit of Terminalia chebula Retzius has been used as a panacea in India and Southeast Asia but its biological activities have not been fully elucidated. Here we report anti-arthritic and analgesic effect of NDI10218, a standardized ethanol extract of Terminalia chebula, on collagen-induced arthritis and acetic acid-induced writhing model, respectively. Arthritis was induced in DBA/1J mice by immunizing bovine type II collagen and mice were treated with NDI10218 daily for 5 weeks after the onset of the disease. NDI10218 reduced the arthritis index and blocked the synovial hyperplasia in a dose-dependent manner. The serum levels of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β were significantly reduced in mice treated with NDI10218. Production of the inflammatory IL-17, but not immunosuppressive IL-10, was also inhibited in splenocytes isolated from NDI10218-treated arthritis mice. Administration of NDI10218 markedly decreased the number of T cell subpopulations in the regional lymph nodes of the arthritis mice. Finally, NDI10218 reduced the number of abdominal contractions in acetic acid-induced writhing model, suggesting an analgesic effect of this extract. Taken together, these results suggest that NDI10218 can be a new therapeutic candidate for the treatment of rheuma-toid arthritis.     

A modified method of measuring plasma volume with indocyanine green: reducing the frequency of blood sampling while maintaining accuracy

Among various methods for measuring the plasma volume (PV), the indocyanine green (ICG) dilution technique is a relatively less invasive method. However, the ICG method is rather cumbersome because 10 blood samples need to be obtained within a short time after ICG administration. Thus, reducing the frequency of blood sampling while maintaining the accuracy would facilitate plasma volume measurement in clinical situations. We here developed a modified method to measure plasma volume using 2260 ICG plasma concentration data from 115 surgical patients. The mean relative error (MRE) and the percentage of cases with relative error (RE) greater than 5% in total (PRE) were used to quantify the difference between plasma volumes obtained by the original and modified methods. RE was determined as follows. RE(%)?=?(PV obtained by original method (PV_original)—PV obtained by modified method (PV_modified))/PV_original?×?100. PV_modified was assumed to be equal to PV_original when the RE was?<?5%. When the number of samples selected for the plasma volume estimation was 4 or less, the PRE was mostly 10% or more. Five out of the 10 blood samples (order: 1st, 2nd, 3rd, 9th, and 10th) showed similar accuracies with the plasma volume obtained by the original method (original: 2.72?±?0.64 l, modified: 2.72?±?0.65 l). This modified method may be able to aptly replace the original method and lead to a wider clinical application of the ICG dilution technique. Further validation is needed to determine if the results of this study may be applied in other populations.

     

The effects of intermittent hypoxia on human nasal mucosa

Sleep and Breathing - Intermittent hypoxia (IH) is characterized by hypoxia-reoxygenation, reported to be a critical risk factor for obstructive sleep apnea (OSA). This experiment aimed to evaluate...     

Clinical Practice Guideline: Nasal Irrigation for Chronic Rhinosinusitis in Adults

The Korean Society of Otorhinolaryngology-Head and Neck Surgery and Korean Rhinologic Society appointed a guideline development group (GDG) to establish a clinical practice guideline, and the GDG developed a guideline for nasal irrigation for adult patients with chronic rhinosinusitis (CRS). The guideline focuses on knowledge gaps, practice variations, and clinical concerns associated with nasal irrigation. Nasal irrigation has been recommended as the first-line treatment for CRS in various guidelines, and its clinical effectiveness has been demonstrated through a number of studies with robust evidence. However, no guidelines have presented a consistent nasal irrigation method. Several databases, including OVID Medline, Embase, the Cochrane Library, and KoreaMed, were searched to identify all relevant papers using a predefined search strategy. When insufficient evidence was found, the GDG sought expert opinions and attempted to fill the evidence gap. Evidence-based recommendations for practice were ranked according to the American College of Physicians grading system. The committee developed 11 evidence-based recommendations. This guideline focuses on the evidence-based quality improvement opportunities deemed the most important by the GDG. Moreover, the guideline addresses whether nasal lavage helps treat CRS, what type of rinsing solution should be used, and the effectiveness of using additional medications to increase the therapeutic effect.