Matlab-Based Study on Online Monitoring of Respiratory Resistance and Compliance under Noninvasive Positive Airway Pressure Ventilation / 医用生物力学

Objective Under noninvasive positive pressure ventilation, in view of inconvenient operations in human airway, and avoiding the interference of spontaneous breathing and the necessary leakage flow, the method for dynamic online monitoring of the respiratory resistance (R) and compliance (C) was studied.Methods At the end of expiration, when the exhaled flow was 0, relative to the expiration positive airway pressure (EPAP), a step-dropped pressure was produced with the amplitude Δp and hold time Δt. Under this dropped pressure, a short-time discharged flow was generated from the lung, and the discharged flow was applied to calculate the R and C. In addition, a respiratory model was developed in MATLAB to simulate the breaths of normal adult, acute respiratory distress syndrome (ARDS) patient and chronic obstructive pulmonary disease (COPD) patient. A serial of simulation experiments were carried out for obtaining data and verification.Results The calculated R and C from simulation for normal adult, ARDS patient, COPD patient, deviated from the actual value by 1.60% and -1.60%, 1.21% and -1.19%, -12.53% and 14.32%, respectively.Conclusions The proposed algorithm is practicable and feasible for calculating the R and C. The simulation results are beneficial for studying and realizing the intelligent ventilation and proportional assist ventilation in respirator.

Actividad física, condición física y factores de riesgo cardio-metabólicos en adultos jóvenes de 18 a 29 años / Physical activity, physical condition and cardio-metabolic risk factors in young adults aged 18 to 29

Introducción. La actividad física y condición física son determinantes de los factores de riesgo cardiometabólicos, pudiendo influenciar en la incidencia de enfermedades crónicas no transmisibles. Objetivos. Analizar la asociación entre nivel de actividad física, condición física y factores de riesgo cardio-metabólicos en adultos jóvenes. Diseño. Estudio observacional, analítico y transversal. Lugar. Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Participantes. Estudiantes de pregrado de las escuelas académico profesionales. Intervenciones. La muestra fue no probabilística, seleccionada por conveniencia, estuvo conformada por 149 hombres y mujeres que consintieron voluntariamente su participación. Se excluyó aquellos con patología cardiaca, metabólica o discapacidad física que impidiera realizar las evaluaciones. Principales medidas de resultados. Nivel de actividad física (NAF), condición física, factores de riesgo cardio-metabólicos. Resultados. El 48,9% de participantes presentó NAF alta; 53,7% tenía uno o dos factores de riesgo alterados: HDL-colesterol bajo (43%), hipertensión (8,7%), hiperglicemia (4%), hipertrigliceridemia (2,7%). El 40,9% de mujeres y 35,6% de varones lograron resultados óptimos en la evaluación de resistencia cardio-respiratoria. El 49% de varones y 34,9% de mujeres alcanzaron resultados óptimos en la evaluación de fuerza abdominal. El 94,6% y 53,7% de participantes tuvieron resultados regulares o deficientes en las evaluaciones de fuerza de miembros inferiores y superiores, respectivamente. Conclusiones. El nivel de actividad física alto estuvo asociado al sexo masculino, presión arterial alta, hipertrigliceridemia, sobrepeso/obesidad, y resultados óptimos de resistencia cardio-respiratoria y fuerza abdominal, en los sujetos estudiados.

Introduction: Physical activity and physical condition are determinants of cardio-metabolic risk factors, and may influence the incidence of chronic non-communicable diseases. Objectives: To analyze the association between physical activity level, physical condition and cardio-metabolic risk factors in young adults. Design: Observational, analytical and transversal study. Setting: Faculty of Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru. Participants: Graduate students from professional academic schools. Interventions: The sample was non-probabilistic, selected by convenience, it was formed by 149 men and women who voluntarily consented to participate. Those with cardiac, metabolic or physical disability which prevented the evaluation were excluded. Main outcome measures: Physical activity level (PAL), physical condition, cardio-metabolic risk factors. Results: 48.2% of the participants had high PAL. 53.7% had one or two altered cardio-metabolic risk factors: low HDL-cholesterol (43%), hypertension (8,7%), hyperglycemia (4%),hypertriglyceridemia (2.7%). 40.9% of women and 35.6% of men achieved optimal results in the evaluation of cardio-respiratory resistance. 49% of males and 34.9% of females obtained optimal results in abdominal strength assessment. 94.6% and 53.7% of participants achieved regular or deficient results in strength assessments of lower and upper limbs, respectively. Conclusions: In the subjects studied, high physical activity level was associated with the male sex, arterial hypertension, hypertriglyceridemia, overweight / obesity, and optimal results of cardio-respiratory resistance and abdominal muscle strength tests.

Inspiratory and Expiratory Resistances During Exercise.

Aims: Paradoxical vocal fold motion, especially during exercise, causes symptoms of dyspnea in patients experiencing this condition. At present, the standard means to diagnose this condition is invasive using a laryngoscope. The Airflow Perturbation Device (APD) could offer a simpler means of diagnosis and monitoring, but the APD must be validated with laryngoscopy. Both devices require access to the mouth, and so cannot be used simultaneously. The aim of this study was to determine if respiratory resistance of exercising subjects changes immediately after exercise begins and ends. Study Design: The study was conducted as a prospective study. Place and Duration of Study: All tests were conducted in the Human Performance Laboratory, Fischell Department of Bioengineering, University of Maryland, College Park, MD between August 2011 and August 2012. Methodology: Fifteen subjects exercised on a bicycle ergometer at 70% of maximum predicted heart rate while breathing through the APD. Results: Results show that APD measurements made just prior and after the cessation of exercise are comparable. Conclusion: APD measured inspiration and expiration resistances do not change immediately after exercise cessation.

Measurement of respiratory resistance and its variability based on forced oscillation technique / 医用生物力学

Objective To validate the significance of forced oscillation technique (FOT) for diagnosis of asthma by using it to measure respiratory resistance of adult asthma patients and healthy subjects. Methods Respiratory resistance was measured by a hand-held FOT device for 5 adult asthma patients and 5 adult healthy subjects, respectively. The variation of respiratory resistance with time was also compared by statistical analysis. Results The respiratory resistance measured by FOT varied periodically with time in all cases, with the respiratory resistance for asthma patients was (294.98±86.24) and for the healthy subjects was (151.9±39.20) Pa•s/L, respectively, showing significant differences in two groups. Conclusions FOT measurement results showed that asthma patients exhibited a greater magnitude and variability of respiratory resistance as compared to their healthy counterparts, which was in agreement with the conventional diagnosis. FOT can provide a novel method for detecting mechanical parameters of the respiratory system in clinic, and as an important reference particularly for the accurate diagnosis of lung dysfunction, such as asthma.

Effects of sevoflurane and desflurane on respiratory mechanics after tracheal intubation in children / 대한마취과학회지

BACKGROUND: Tracheal intubation causes a reflex tracheal constriction that leads to increased airway resistance. Inhalation anesthetics can prevent or minimize this response. Therefore, this study was conducted to evaluate the effect of 1 MAC sevoflurane or desflurane on respiratory mechanics in children after anesthetic induction using propofol and tracheal intubation. METHODS: Sixty children undergoing elective surgery with tracheal intubation were assigned into two groups at random, a 1 MAC concentration of sevoflurane (n = 30) and a desflurane (n = 30) group. Anesthesia was induced using propofol (1.5 mg/kg) and tracheal intubation was facilitated using rocuronium (0.6 mg/kg). A respiratory profile monitor was used to measure the respiratory resistance, dynamic compliance and peak inspiratory airway pressure. The measurements were made at three time points, after three inspirations from the beginning of mechanical ventilation (baseline) and at 5 and 10 min after the administration of inhalation anesthetics. RESULTS: Sevoflurane and desflurane led to a significant decrease in respiratory resistance and increased dynamic compliance at 5 and 10 min when compared to baseline. There were no significant differences in respiratory resistance and dynamic compliance between the two groups. CONCLUSIONS: A 1 MAC concentration of sevoflurane and desflurane has a similar bronchodilatory effect after tracheal intubation in children.

The Change of Respiratory Mechanics by a Bronchodilator Inhalation Under the Variable Level of PEEP in Patients with Acute Respiratory Distress Syndrome / 결핵

BACKGROUND: Reduced lung compliance and increased lung resistance are the primary lung mechanical abnomalities in acute respiratory distress syndrome (ARDS). Although there is little information regarding the mecha nisms responsible for the increases in the respiratory resistance of ARDS, bronchodilators have been frequently administered in mechanically ventilated ARDS patient. To determine the effect of a bronchodilator on the respiratory mechanics depending on the level of applied positive end-expiratory pressure (PEEP), the change in the respiratory mechanics by salbutamol ingalation was measured under the variable PEEP level in patients with ARDS. METHODS: Fifteen mechanically ventilated paralyzed ARDS patientss (14 of male, mean age 57 years) were enrolled in this study. The respiratory system compiance, and the maximum and minimun inspiratory occlusion method during constant flow inflaction using the CP-100 pulmonary monitor (Bicore, Irvine, CA, USA). The measurements were performed at randomly applied 8, 10 and 12 cm H2O PEEP before and 30 mins after administrating salbutamol using a meter-dose-inhaler (100 micro gram X 6). RESULTS: 1) The maximum inspiratory resistance of the lung was higher than the reported normol values due to an increase in the minimal inspiratory resistance and additional resistance. 2) The maximum inspiratory resistance and peak airway pressure were significantly higher at 12 cm H2O of PEEP compared with those at 10cm H2O of PEEP. 3) Salbutamol induced a significant decrease in the maximum and the minimum inspiratory resistance but no significant change in the additional resistance only was observed at 12 cm H2O of PEEP (from 15.66+/-1.99 to 13.54+/-2.41, from 10.24+/-2.98 to 8.04+/-2.34, and from 5.42+/-3.41 to 5.50+/-3.58 cm H2O/l/sec, respectively). 4) The lung compliance did not change at the applied PEEP and salbutamol inhalation levels. CONCLUSIONS: The bronchodiator response would be different depending on the level of applied PEEP despite the increased respiratory resistance in patients with ARDS.

Effects of CO_2 pneumoperitoneum on pulmonary functions in rabbits with chronic pulmonary failure:An experimental study / 中国微创外科杂志

Objective To investigate the effects of CO 2 pneumoperitoneum during laparoscopic cholecystectomy (LC) on pulmonary functions in chronic pulmonary failure rabbits and their mechanisms. Methods A total of 50 healthy male rabbits ( oryctolagus cuniculus ) were randomly divided into 4 groups: normal control group (N 0: n=5, no pneumoperitoneum), experimental control group (T 0: n=5, no pneumoperitoneum), 10 mmHg experimental group (T 10 : n=20, 10 mmHg pneumoperitoneum) and 15 mmHg experimental group (T 15 : n=20, 15 mmHg pneumoperitoneum). After the successful establishment of emphysema rabbit models, CO 2 pneumoperitoneum was conducted and maintained for 2 hours at the pressure of 10 mmHg (1.33 kPa) and 15 mmHg (2.00 kPa), respectively. Pulmonary functions (total respiratory resistance, central resistance and total airway resistance) of the 4 groups were measured by pulse oscillation technique before and after the pneumoperitoneum, respectively. Results Total respiratory resistance, central resistance and total airway resistance increased after the establishment of emphysema models. And they decreased at the end of pneumoperitoneum compared with those before pneumoperitoneum ( q=17.824, P

Endotracheal Intubation, but not Laryngeal Mask Airway Insertion, Produces Reversible Bronchoconstriction / 대한마취과학회지

BACKGROUND: Intubation of the trachea frequently results in a rise in respiratory system resistance (Rrs) that is reversed by inhaled bronchodilators. In asthmatics, this reflex may occasionally result in profound bronchoconstriction, and anesthesiologists often try to avoid tracheal intubation if possible in asthmatics. The hypothesis of this study was that insertion of a laryngeal mask airway (LMA) would be less likely to result in reversible bronchoconstriction than would insertion of an endotracheal tube (ETT). METHODS: A total of 52 (45 male, 7 female) patients were randomized to placement of a 7.5 mm (females) or 8.0 mm (males) endotracheal tube or a #4 (females) or #5 LMA (males). Anesthesia was induced with 2 microgram/kg fentanyl and 5 mg/kg thiopental and airway placement facilitated with 1 mg/kg succinylcholine. After ensuring that a seal to greater than 20 cmH2O existed, Rrs was measured immediately following airway placement using the isovolumic method during positive pressure ventilation with oxygen. Correction was made for the resistance of the ETT but not for the resistance of the LMA, which was insignificant at the flows used. Inhalation anesthesia was then begun with isoflurane (ISF) to achieve an end-tidal concentration of 1.0% for ten minutes. Rrs was then measured again under identical conditions. In the LMA patients, fiberoptic laryngoscopy was then performed to ensure that the scope could be passed to the level of the cords without epiglottic obstruction. RESULTS: Among LMA patients, the initial Rrs was significantly lower than among ETT patients (9.2 0.7 vs 13.4 1.9 cmH2O/L/s, P <0.05). After 10 minutes of ISF, the resistance declined to 8.6 0.7 in the ETT group but remained unchanged at 9.1 0.7 cmH2O/L/s in the LMA group. The decline in Rrs in the ETT group of 4.7 1.4 cmH2O/L/s was highly significant compared to the lack of change in the LMA group (P <0.01). CONCLUSIONS: Despite the inclusion of the resistance of the LMA and the laryngeal resistance, Rrs in LMA patients was still clearly lower than in ETT patients. Furthermore, resistance dropped rapidly only in ETT patients after ISF, a potent bronchodilator, suggesting that reversible bronchoconstriction was present in ETT patients but not LMA patients. We conclude that an LMA is a better choice of airway to minimize airway reaction.

Endotracheal Intubation, but not Laryngeal Mask Airway Insertion, Produces Reversible Bronchoconstriction / 대한마취과학회지

BACKGROUND: Intubation of the trachea frequently results in a rise in respiratory system resistance (Rrs) that is reversed by inhaled bronchodilators. In asthmatics, this reflex may occasionally result in profound bronchoconstriction, and anesthesiologists often try to avoid tracheal intubation if possible in asthmatics. The hypothesis of this study was that insertion of a laryngeal mask airway (LMA) would be less likely to result in reversible bronchoconstriction than would insertion of an endotracheal tube (ETT). METHODS: A total of 52 (45 male, 7 female) patients were randomized to placement of a 7.5 mm (females) or 8.0 mm (males) endotracheal tube or a #4 (females) or #5 LMA (males). Anesthesia was induced with 2 microgram/kg fentanyl and 5 mg/kg thiopental and airway placement facilitated with 1 mg/kg succinylcholine. After ensuring that a seal to greater than 20 cmH2O existed, Rrs was measured immediately following airway placement using the isovolumic method during positive pressure ventilation with oxygen. Correction was made for the resistance of the ETT but not for the resistance of the LMA, which was insignificant at the flows used. Inhalation anesthesia was then begun with isoflurane (ISF) to achieve an end-tidal concentration of 1.0% for ten minutes. Rrs was then measured again under identical conditions. In the LMA patients, fiberoptic laryngoscopy was then performed to ensure that the scope could be passed to the level of the cords without epiglottic obstruction. RESULTS: Among LMA patients, the initial Rrs was significantly lower than among ETT patients (9.2 0.7 vs 13.4 1.9 cmH2O/L/s, P <0.05). After 10 minutes of ISF, the resistance declined to 8.6 0.7 in the ETT group but remained unchanged at 9.1 0.7 cmH2O/L/s in the LMA group. The decline in Rrs in the ETT group of 4.7 1.4 cmH2O/L/s was highly significant compared to the lack of change in the LMA group (P <0.01). CONCLUSIONS: Despite the inclusion of the resistance of the LMA and the laryngeal resistance, Rrs in LMA patients was still clearly lower than in ETT patients. Furthermore, resistance dropped rapidly only in ETT patients after ISF, a potent bronchodilator, suggesting that reversible bronchoconstriction was present in ETT patients but not LMA patients. We conclude that an LMA is a better choice of airway to minimize airway reaction.

Change of respiratory resistance by water immersion and exercie in patients with chronic obstructive pulmonary disease / 日本温泉気候物理医学会雑誌

The effect of underwater exercise on respiratory resistance (Rrs) was examined in 12 patients with chronic obstructive pulmonary disease (COPD). Rrs was measured while the patients were sitting on land with quiet respiration, while immersed in water (at 38°C) up to the upper abdomen and upper chest in standing position, and while sitting on land with quiet respiration after mild underwater exercise. The mean Rrses in each condition were 0.37, 0.37, 0.42, 0.33kp/1/s. Rrs increased by 14% (p<0.005) after immersion in water up to the upper chest and decreased by 12% (p<0.001) after underwater exercise. The change after exercise showed a popitive correlation with FEV_1.0/FVC on spirogram. Although water immersion or underwater exercise of these COPD patients caused a slight load in ventilation, no significant aggravation of the subjective symptom was found.<br>The above results suggested that uoderwater exercise was beneficial as a physical treatment for mild cases of COPD.