• Journal of Biomedical Engineering Research
• /
• v.13 no.3
• /
• pp.209-216
• /
• 1992

A new experimental technique is proposed to localize the flow limiting segment(FLS) during forced expiration. The present technique is based on the pressure drip across FLS and a consequent change in airway resistance, which can provide an accurate and objective location of FLS. During forced expiratory maneuver artificially induced by a strong negative pressure (-100mmHg) applied at the trachea in an anesthetized open chest dog, airway resistance( R) was calculated from air flow and airway pres- sure signals at various airway locations and lung volumes, At the lung volumes above 10 % VC, FLS located in the trachea 6cm lower from the larynx. With the lung volume decreased below 8% VC, FLS jumped upstream to End-3rd generation of the airway. These results were similar with the previous reports from excised dog lungs, which demonstrated the validity of the present technique. Since the present technique provides a more objective measure of FLS location, it would be useful in future studies of expiratory flow limitation.

• Tuberculosis and Respiratory Diseases
• /
• v.42 no.5
• /
• pp.723-730
• /
• 1995

Background: Noninvasive ventilation has been used extensively for the treatment of patients with neuromuscular weakness or restrictive chest wall disorders complicated by hypoventilatory respiratory failure. Recently, noninvasive positive pressure ventilation has been used in patients with alveolar hypoventilation, chronic obstructive pulmonary disease(COPD), and adult respiratory distress syndrome. Sanders and Kern reported treatment of obstructive sleep apnea with a modification of the standard nasal CPAP device to deliver seperate inspiratory positive airway pressure(IPAP) and expiratory positive airway pressure(EPAP). Bi-level positive airway pressure(BiPAP) unlike nasal CPAP, the unit delivers a different pressure during inspiration from that during expiration. The device is similar to the positive pressure ventilator or pressure support ventilation. Method and purpose: Bi-level positive airway pressure(BiPAP) system(Respironics, USA) was applied to seven patients with acute respiratory failure and three patients on conventional mechanical ventilation. Results: 1) Two of three patients after extubation were successfully achieved weaning from conventional mechanical ventilation by the use of BiPAP ventilation with nasal mask. Five of seven patients with acute respiratory failure successfully recovered without use of conventional mechanical ventilation. 2) $PaO_2$ 1hour after BiPAP ventilation in acute respiratory failure patients significantly improved more than baseline values(p<0.01). $PaCO_2$ 1hour after BiPAP ventilation in acute respiratory failure patients did not change significantly more than baseline values. Conclusion: Nasal mask BiPAP ventilation can be one of the possible alternatives of conventional mechanical ventilation in acute respiratory failure and supportive method for weaning from mechanical ventilation.

• Sleep Medicine and Psychophysiology
• /
• v.7 no.1
• /
• pp.27-33
• /
• 2000

Objectives: The sensitivity and accuracy of thermistor airflow signal has been debated. The purposes of this study were to compare apnea-hypopnea index(AHI) detected from a conventional thermistor signal and a nasal pressure transducer of airflow(NPT), to evaluate the value of NPT for the diagnosis of upper airway resistance syndrome(UARS), and to measure airway pressure fluctuations which produced respiratory arousals in UARS by naso-oro-esophageal manometer catheter. The subjects were 30 patients with obstructive sleep apnea syndrome [mild(540), 10), and 6 UARS patients. Airway resistance arousal in this study was defined as arousals which were not associated with apnea or hypopnea of thermistor signal, but showed significant decrease of nasal airflow pressure just before arousal and a prompt recovery of nasal airflow pressure after arousal. The airway pressure fluctuations were measured during 260 airway resistance arousals observed in 10 patients with OSAS, 2 with UARS. Results: Mean AHIs of patients with OSAS were 33.4 by thermistor and 48.4 by NPT. The AHIs of mild, moderate and severe OSAS groups were 10.2, 32.1, 65.4 respectively by thermistor and 23.1, 45.9, 76.4 by NPT. The mean AHI of patients with UARS was 3.2 by thermistor and 10.8 by NPT. The mean AHI of patients with nonspecific arousals was 2.7 by thermistor and 4.4 by NPT. The mean airway pressure changes during respiratory arousals of different groups were $8.7\;cmH_2O$ in mild OSAS, $11.4\;cmH_2O$ in moderate OSAS, $24.7\;cmH_2O$ in severe OSAS and $6.6\;cmH_2O$ in UARS. Conclusion: The nasal pressure transducer of airflow was more sensitive and accurate for assessing respiratory disturbances of patients with OSAS and was extremely helpful for the diagnosis of UARS without esophageal pressure monitoring. From the results, we would like to propose carefully the NPT diagnostic criteria for sleep disordered breathing as follows: NPT-AHI 5-15 $\rightarrow$ UARS, 15-35 $\rightarrow$ mild OSAS, 35-55 $\rightarrow$ moderate OSAS and >55 $\rightarrow$ severe OSAS.

• The Korean Journal of Emergency Medical Services
• /
• v.18 no.2
• /
• pp.35-43
• /
• 2014

Purpose: The purpose of this study was to establish novice user guidelines for efficient external laryngeal manipulation for intubation in difficult airway management. Methods: This study included 59 pre-qualified junior and senior emergency medical service students. The participants were instructed at random to intubate a manikin equipped with a cervical collar, thus simulating a difficult airway, using three types of external laryngeal manipulation: bimanual laryngoscopy, backward-rightward pressure, and cricoid pressure. The resultant intubation time and glottic view grade scores were estimated. Results: Intubation time was longest using the bimanual manipulation method, followed by cricoid pressure and backward-rightward pressure. A low Cormack-Lehane glottic view score was obtained regardless of the assisted compression method used. Conclusion: Backward-rightward pressure may be the most efficient method of external laryngeal manipulation on the basis of the intubation time and improvement in glottic view.

• Fire Science and Engineering
• /
• v.28 no.6
• /
• pp.76-81
• /
• 2014

The purpose of this study was to comparative analysis of tidal volume and airway pressure after one-rescuer BVM, two-rescuer BVM, advanced airway devices with a Bag-valve mask using RespiTrainer. The data were obtained from June 2 to 10 in 2014. The collected data were analyzed using the SPSS WIN 18.0 program. The results showed that BVM ventilation using the endotracheal intubation produced higher mean tidal volume $497{\pm}78mL$, Two-rescuer ventilation $479{\pm}91mL$ One-rescuer ventilation $386{\pm}59mL$, King LTS-D $365{\pm}05mL$, Laryngeal mask airway (LMA) $351{\pm}35mL$. Peak airway pressure was higher in BVM ventilation using the endotracheal intubation. As a result, the study confirmed that the BVM Ventilation by endotracheal intubation and Two-rescuer BVM ventilation to one third the bag depth squeeze method is appropriate.

• Radiation Oncology Journal
• /
• v.36 no.1
• /
• pp.79-84
• /
• 2018

Deep inspiration breathing hold (DIBH) compared to free-breathing (FB) during radiotherapy (RT) has significantly decreased radiation dose to heart and has been one of the techniques adopted for patients with breast cancer. However, patients who are unable to make suitable deep inspiration breath may not be eligible for DIBH, yet still need to spare the heart and lung during breast cancer RT (left-sided RT in particular). Continuous positive airway pressure (CPAP) is a positive airway pressure ventilator, which keeps the airways continuously open and subsequently inflates the thorax resembling thoracic changes from DIBH. In this report, authors applied CPAP instead of FB during left-sided breast cancer RT including internal mammary node in a patient who was unable to tolerate DIBH, and substantially decreased radiation dose the heart and lung with CPAP compared to FB.

• Journal of Biomedical Engineering Research
• /
• v.40 no.4
• /
• pp.132-136
• /
• 2019

This study proposes an auto-titrating algorithm for auto-titrating positive airway pressure (APAP). The process of the proposed algorithm is as follows. First, sleep apnea-hypopnea and snoring events were detected using nasal pressure. Second, APAP base pressure and SDB events were used for automatic titration of optimal pressure. And, auto-titrating algorithm is built into M3 (MEK-ICS CO. Ltd., Republic of Korea) for evaluation. The detection results of SDB showed mean sensitivity (Sen.) and positive predictive value (PPV.) of 85.7% and 87.8%, respectively. The mean pressure and apnea-hypopnea index (AHI) of auto-titrating algorithm showed $13.0{\pm}5.2cmH_2O$ and $3.0{\pm}2.4$ events/h, respectively. And, paired t-test was conducted to verify whether the performance of our algorithm has no significant difference with AutoSet S9 (p>0.05). These results represent better or comparable outcomes compared to those of previous APAP devices.

• Journal of Yeungnam Medical Science
• /
• v.21 no.1
• /
• pp.127-131
• /
• 2004

A laryngeal mask airway (LMA) has many advantages in the management of airway emergencies or the treatment of patients in whom intubation is difficult, but the use of LMA during positive ventilation may seem inappropriate to protect the airway because of the risk of pulmonary aspiration of regurgitated gastric contents. We experienced aspiration pneumonia after general anesthesia using LMA in patient who suffered from panperitonitis. It is considered that the main reason for aspiration pneumonia was a leakage of gastric content through the space surrounding the nasogastric tube while under high airway inflation pressure. We concluded that when LMA or the Proseal laryngeal mask airway (PLMA) is chosen for the use in difficult intubations, careful patient-suitability selection and the correct knowledge of LMA and PLMA are needed to protect the airway against aspiration.

• Speech Sciences
• /
• v.14 no.4
• /
• pp.261-271
• /
• 2007

The purpose of this study was to determine the effectiveness of CPAP (Continuous Positive Airway Pressure) therapy on the treatment of hypernasality in patients with cleft lips and palates. 7 preschool children with severe hypernasality participated in the study. Acoustic measurements of nasality were done by using the NasalView (version 1.31). Results showed that the nasalance values were reduced linearly in both vowels according to the treatment period. The sharp treatment effect was observed at the beginning stage. The nasality values of the vowel /i/ showed a sharp decrease at the Evaluation Phase 1 and 2 and a small increase at the Phase 4 followed by a drop in the end. Further studies would be desirable for various patients with different disorder types.

• Sleep Medicine and Psychophysiology
• /
• v.23 no.2
• /
• pp.97-99
• /
• 2016

Positive airway pressure (PAP) is currently recommended as a primary treatment for obstructive sleep apnea syndrome (OSAS) and positively affects various subjective and objective parameters related to OSAS, such as the apnea-hypopnea index, excessive daytime sleepiness, and blood pressure. However, PAP also exhibits various adverse effects, including skin breakdown, pressure intolerance, claustrophobia, unintentional mask removal, mouth leaks, and dryness. Especially, unintentional mask removal due to nasal obstruction may result in poor PAP compliance. A 47-year-old male patient with severe OSAS who had low PAP compliance due to nasal obstruction underwent nasal surgery. After the surgery, nasal obstruction was corrected and the patient experienced improved PAP compliance (from 30.4% to 86.7%). This case demonstrates that nasal surgery may be useful for improving PAP compliance in OSAS patients with nasal obstruction.