scholarly journals Dynamic Characteristics of Mechanical Ventilation System of Double Lungs with Bi-Level Positive Airway Pressure Model

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Dongkai Shen ◽  
Qian Zhang ◽  
Yan Shi

In recent studies on the dynamic characteristics of ventilation system, it was considered that human had only one lung, and the coupling effect of double lungs on the air flow can not be illustrated, which has been in regard to be vital to life support of patients. In this article, to illustrate coupling effect of double lungs on flow dynamics of mechanical ventilation system, a mathematical model of a mechanical ventilation system, which consists of double lungs and a bi-level positive airway pressure (BIPAP) controlled ventilator, was proposed. To verify the mathematical model, a prototype of BIPAP system with a double-lung simulators and a BIPAP ventilator was set up for experimental study. Lastly, the study on the influences of key parameters of BIPAP system on dynamic characteristics was carried out. The study can be referred to in the development of research on BIPAP ventilation treatment and real respiratory diagnostics.

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yan Shi ◽  
Shuai Ren ◽  
Maolin Cai ◽  
Weiqing Xu

Secretions of ventilated patients must be cleared efficiently and timely; to improve the secretion clearance efficiency of an insufflation-exsufflation device (IL-IE device) and lay a foundation for the optimization of the IL-IE device, a mathematical model of the ventilation system with the IL-IE device is set up. Through the experimental and simulation research on the ventilation system, it can be concluded that, firstly, the mathematical model is proved to be authentic and reliable. Secondly, with the deposition of secretion or an increase in the respiratory compliance, the peak exsufflation airflow may be reduced. Thirdly, with a decrease in the suction pressure, the peak exsufflation airflow of the ventilated lung may rise proportionally, but the minimum pressure in the ventilated lung may descend proportionally. To improve the efficiency of the secretion clearance but not to injure the ventilated patient, the suction pressure can be elevated properly. Last, increasing the inspiratory positive airway pressure (IPAP) is a method to improve the secretion clearance efficiency. This research lays a foundation for improving the secretion clearance efficiency of the IL-IE device.


2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yan Shi ◽  
Shuai Ren ◽  
Maolin Cai ◽  
Weiqing Xu ◽  
Qiyou Deng

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.


2015 ◽  
Vol 15 (03) ◽  
pp. 1550032 ◽  
Author(s):  
YAN SHI ◽  
JINGLONG NIU ◽  
MAOLIN CAI ◽  
WEIQING XU

To improve the efficiency and safety of secretion clearance, a novel ventilator (SC ventilator) with an automatic secretion clearance function is proposed. To lay a foundation for the optimization of the SC ventilator, the basic mathematical model of the ventilation system is derived. By selecting the appropriate reference values, the basic mathematical model is transformed to a dimensionless expression for simulation. Through the experimental and simulation study on the SC ventilation system, it can be concluded that: firstly, the mathematical model is proved to be authentic and reliable. Secondly, the influences of the three key parameters on the dynamics of the SC ventilation system are carried out. Last, to guarantee the pressure in the lung is higher than the expiratory positive airway pressure, the dimensionless minimum pressure in the flexible tube should be set higher than 0.9164, the dimensionless suction pressure should be set higher than 0.79.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Arash Malakian ◽  
Mohammad Reza Aramesh ◽  
Mina Agahin ◽  
Masoud Dehdashtian

Abstract Background The most common cause of respiratory failure in premature infants is respiratory distress syndrome. Historically, respiratory distress syndrome has been treated by intratracheal surfactant injection followed by mechanical ventilation. In view of the risk of pulmonary injury associated with mechanical ventilation and subsequent chronic pulmonary lung disease, less invasive treatment modalities have been suggested to reduce pulmonary complications. Methods 148 neonates (with gestational age of 28 to 34 weeks) with respiratory distress syndrome admitted to Imam Khomeini Hospital in Ahwaz in 2018 were enrolled in this clinical trial study. 74 neonates were assigned to duo positive airway pressure (NDUOPAP) group and 74 neonates to nasal continuous positive airway pressure (NCPAP) group. The primary outcome in this study was failure of N-DUOPAP and NCPAP treatments within the first 72 h after birth and secondary outcomes included treatment complications. Results there was not significant difference between DUOPAP (4.1 %) and NCPAP (8.1 %) in treatment failure at the first 72 h of birth (p = 0.494), but non-invasive ventilation time was less in the DUOPAP group (p = 0.004). There were not significant differences in the frequency of patent ductus arteriosus (PDA), pneumothorax, intraventricular hemorrhage (IVH) and bronchopulmonary dysplasia (BPD), apnea and mortality between the two groups. Need for repeated doses of surfactant (p = 0.042) in the NDUOPAP group was significantly lower than that of the NCPAP group. The duration of oxygen therapy in the NDUOPAP group was significantly lower than that of the NCPAP group (p = 0.034). Also, the duration of hospitalization in the NDUOPAP group was shorter than that of the NCPAP group (p = 0.002). Conclusions In the present study, DUOPAP compared to NCPAP did not reduce the need for mechanical ventilation during the first 72 h of birth, but the duration of non-invasive ventilation and oxygen demand, the need for multiple doses of surfactant and length of stay in the DUOPAP group were less than those in the CPAP group. Trial registration IRCT20180821040847N1, Approved on 2018-09-10.


1998 ◽  
Vol 89 (4) ◽  
pp. 942-953 ◽  
Author(s):  
Willehad Boemke ◽  
Martin O. Krebs ◽  
Kourosh Djalali ◽  
Harald Bunger ◽  
Gabriele Kaczmarczyk

Background The role of renal nerves during positive end-expiratory pressure ventilation (PEEP) has only been investigated in surgically stressed, anesthetized, unilaterally denervated dogs. Anesthesia, sedation, and surgical stress, however, decrease urine volume and sodium excretion and increase renal sympathetic nerve activity independent of PEEP. This study investigated in awake dogs the participation of renal nerves in mediating volume and water retention during PEEP. Methods Eight tracheotomized, trained, awake dogs were used. The protocol consisted of 60 min of spontaneous breathing at a continuous positive airway pressure of 4 cm H2O, followed by 120 min of controlled mechanical ventilation with a mean PEEP of 15-17 cm H2O (PEEP), and 60 min of continuous positive airway pressure. Two protocols were performed on intact dogs, in which volume expansion had (hypervolemic; electrolyte solution, 0.5 ml x kg(-1) x min(-1)) and had not (normovolemic) been instituted. This was repeated on the same dogs 2 or 3 weeks after bilateral renal denervation. Results Hypervolemic dogs excreted more sodium and water than did normovolemic dogs. There was no difference between intact and renal-denervated dogs. Arterial pressure did not decrease when continuous positive airway pressure was switched to PEEP. Plasma renin activity, aldosterone, and antidiuretic hormone concentrations were greater in normovolemic dogs. The PEEP increased aldosterone and antidiuretic hormone concentrations only in normovolemic dogs. Conclusions In conscious dogs, renal nerves have no appreciable contribution to sodium and water retention during PEEP. Retention in normovolemic dogs seems to be primarily caused by an activation of the renin-angiotensin system and an increase in the antidiuretic hormone. Excretion rates depended on the volume status of the dogs.


PEDIATRICS ◽  
2003 ◽  
Vol 111 (Supplement_E1) ◽  
pp. e534-e541
Author(s):  
Joseph W. Kaempf ◽  
Betty Campbell ◽  
Ronald S. Sklar ◽  
Cindy Arduza ◽  
Robert Gallegos ◽  
...  

Objective. The purpose of this article is to describe how a neonatal intensive care unit (NICU) was able to reduce substantially the use of postnatal dexamethasone in infants born between 501 and 1250 g while at the same time implementing a group of potentially petter practices (PBPs) in an attempt to decrease the incidence and severity of chronic lung disease (CLD). Methods. This study was both a retrospective chart review and an ongoing multicenter evidence-based investigation associated with the Vermont Oxford Network Neonatal Intensive Care Quality Improvement Collaborative (NIC/Q 2000). The NICU specifically made the reduction of CLD and dexamethasone use a priority and thus formulated a list of PBPs that could improve clinical outcomes across 3 time periods: era 1, standard NICU care that antedated the quality improvement project; era 2, gradual implementation of the PBPs; and era 3, full implementation of the PBPs. All infants who had a birth weight between 501 and 1250 g and were admitted to the NICU during the 3 study eras were included (era 1, n = 134; era 2, n = 73; era 3, n = 83). As part of the NIC/Q 2000 process, the NICU implemented 3 primary PBPs to improve clinical outcomes related to pulmonary disease: 1) gentle, low tidal volume resuscitation and ventilation, permissive hypercarbia, increased use of nasal continuous positive airway pressure; 2) decreased use of postnatal dexamethasone; and 3) vitamin A administration. The total dexamethasone use, the incidence of CLD, and the mortality rate were the primary outcomes of interest. Secondary outcomes included the severity of CLD, total ventilator and nasal continuous positive airway pressure days, grades 3 and 4 intracranial hemorrhage, periventricular leukomalacia, stages 3 and 4 retinopathy of prematurity, necrotizing enterocolitis, pneumothorax, length of stay, late-onset sepsis, and pneumonia. Results. The percentage of infants who received dexamethasone during their NICU admission decreased from 49% in era 1 to 22% in era 3. Of those who received dexamethasone, the median number of days of exposure dropped from 23.0 in era 1 to 6.5 in era 3. The median total NICU exposure to dexamethasone in infants who received at least 1 dose declined from 3.5 mg/kg in era 1 to 0.9 mg/kg in era 3. The overall amount of dexamethasone administered per total patient population decreased 85% from era 1 to era 3. CLD was seen in 22% of infants in era 1 and 28% in era 3, a nonsignificant increase. The severity of CLD did not significantly change across the 3 eras, neither did the mortality rate. We observed a significant reduction in the use of mechanical ventilation as well as a decline in the incidence of late-onset sepsis and pneumonia, with no other significant change in morbidities or length of stay. Conclusions. Postnatal dexamethasone use in premature infants born between 501 and 1250 g can be sharply curtailed without a significant worsening in a broad range of clinical outcomes. Although a modest, nonsignificant trend was observed toward a greater number of infants needing supplemental oxygen at 36 weeks’ postmenstrual age, the severity of CLD did not increase, the mortality rate did not rise, length of stay did not increase, and other benefits such as decreased use of mechanical ventilation and fewer episodes of nosocomial infection were documented.


PEDIATRICS ◽  
1991 ◽  
Vol 88 (6) ◽  
pp. 1153-1160 ◽  
Author(s):  
Debora W. Overstreet ◽  
J. Craig Jackson ◽  
Gerald van Belle ◽  
William E. Truog

Bronchopulmonary dysplasia is a chronic, sometimes fatal lung disease, which primarily affects premature infants and often leads to a dependence on mechanical ventilation lasting many months. To identify prognostic factors of mortality at 1 and 2 months of age, the authors reviewed the medical records of the 144 neonates admitted to two neonatal intensive care units in Seattle from January 1, 1986, through December 31, 1988, who required mechanical ventilation throughout the first month of life. Likely predictors of mortality were tested by logistic regression analysis. The calculated mean airway pressure at 30 days of age (MAP30) and the diagnosis of bacterial sepsis at any time during the first month of life (Bact0-30) were statistically significant predictors of mortality (P < .001 and P = .018, respectively) and had the lowest deviance in the regression model. The probability of mortality was estimated by 1/(1 + e-x, where x = -6.510 + 0.4588 (MAP30) + 1.475 (Bact0-30), and where MAP30 is expressed as centimeters of water pressure (1 cm H2O = 0.0978 kPa) and the presence or absence of bacteremia is 1 and 0, respectively. The records of the 57 infants who still required mechanical ventilation at 60 days of age were reanalyzed with clinical data available during the first 2 months of life. Mean airway pressure (MAP60) and the fraction of inspired oxygen (F60) at 60 days of age combined to form the best predictors of mortality, where x = -7.668 + 0.2940 (MAP60) + 5.935 (F60). The occurrence of bacterial sepsis during the first 2 months of life, the degree of hypochloremia, and the duration of chronic sedative use were also significant predictors of survival, even controlling of MAP60 and F60. These regression equations allow more accurate estimation of the likelihood of survival for chronically ventilated infants and may facilitate decisions regarding withdrawal or continuation of life support.


Lung India ◽  
2017 ◽  
Vol 34 (2) ◽  
pp. 216
Author(s):  
MiguelAngel Palomero Rodriguez ◽  
HéctorChozas de Arteaga ◽  
YolandaLaporta Báez ◽  
Jesúsde Vicente Sánchez ◽  
AntonioPérez Ferrer

2021 ◽  
Author(s):  
Allan Cameron ◽  
Sharif Fattah ◽  
Laura Knox ◽  
Pauline Grose

Abstract Background - During the winter of 2020-2021, the second wave of the COVID19 pandemic in the United Kingdom caused increased demand for intensive care unit (ICU) beds, and in particular, for invasive mechanical ventilation (IMV). To alleviate some of this pressure, some centres offered non-invasive continuous positive airway pressure (CPAP), delivered on specialised COVID high dependency units (cHDUs). However, this practice was based largely on anecdotal reports, and it is not clear from the literature how effective CPAP is at delaying or preventing IMV. Methods - This was a retrospective observational cohort study of consecutive patients admitted to a specialised cHDU at Glasgow Royal Infirmary between November 2020 and February 2021. Each patient had a continuous record of the level of respiratory support required, and was followed up to hospital discharge or death. We examined patient outcomes according to age, sex and maximum level of respiratory support, using logistic regression and time-to-event analysis. The number of patients who could not be oxygenated by standard oxygen facemask but could be oxygenated by CPAP was counted and compared to the number of patients admitted to ICU for IMV over the same period.Results - There were 152 admissions to cHDU over the study period. Of these, 125 received CPAP treatment. Of the patients who received support in cHDU, the overall mortality rate was 37.9% (95% CI 30.3% - 46.1%)). Odds of mortality were closely correlated with increasing age and oxygen requirement. Of the 152 patients, 44 patients (28.8%, 95% CI 22.0 – 36.9%) went on to require IMV in ICU. This represents 77.2% of the 57 COVID-19 admissions to ICU during the same period. However, there were also 41 patients who received levels of respiratory support on cHDU which would normally necessitate ICU admission but who never went to ICU, potentially reducing ICU admissions by 41.8% (95% CI 32.1 – 52.2%).Conclusion - Providing respiratory support in cHDU reduced the number of potential ICU admissions by 41.8%, as well as delaying IMV for over 75% of ICU admissions. This represents a significant sparing of ICU capacity at a time when IMV beds were in high demand.


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