Ventilation Monitoring Research Articles

Monitoring of noninvasive ventilation: comparative analysis of different strategies

BackgroundNoninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO2). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO2) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy.MethodsThis retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO2, TcPCO2 and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO2), B (nocturnal SpO2 + TcPCO2) and C (TcPCO2 + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal).ResultsNIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia.ConclusionMonitoring ABG and nocturnal SpO2 is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO2 seems to represent the best strategy to detect poor NIV efficacy.Trialregistration Institutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges)

Sudden unexpected death after acute symptomatic seizures in a patient on mechanical ventilation

BackgroundThe mechanism of sudden unexpected death in epilepsy remains poorly understood. Seizure induced cardiac arrhythmia, central and obstructive apneas have been proposed as possible causes of death. Here we report a unique case of seizure related sudden unexpected death in a patient whose airway was fully protected by intubation and mechanic ventilation in the absence of fatal cardiac arrhythmia.Case presentationA 70-year-old woman was undergoing mechanical ventilation and video-electroencephalography (EEG) monitoring following two convulsive seizures with ictal hypoventilation and hypoxemia. Several hours after intubation, she suffered another generalized tonic clonic seizure lasted for 3 min and developed postictal generalized EEG suppression in the presence of stable vital signs with SpO2 > 90%. EEG suppression persisted throughout the postictal phase. There was a significant fluctuation of systolic blood pressure between 50 and 180 mmHg with several bouts of hypotension < 60 mmHg. She remained unresponsive after the convulsive seizure and died of diffuse cerebral edema 12 h later. Autopsy revealed no clear cause of death, except for possible hypoxic and ischemic injury leading to the diffuse cerebral edema.ConclusionGiven the reliable periictal airway protection, neither seizure induced central apnea nor obstructive apnea appeared to be the direct cause of death in this unique case. In the absence of fatal cardiac arrhythmia, diffuse cerebral edema secondary to seizure-induced autonomic dysfunction, hypotension and hypoxemia might be the cause of death, highlighting the etiological heterogeneity of sudden unexpected death in epilepsy.

Influence of current injection scheme on electrical impedance tomography for monitoring of the respiratory function of obese subjects

Electrical impedance tomography (EIT) has been proposed as a noninvasive radiation-free functional imaging modality for bedside monitoring of lung ventilation. Due to the intrinsic low sensitivity of measured boundary voltages with respect to internal conductivity changes, EIT image reconstructions are more challenging for the regions that are located deeper from the attached surface electrodes. Considering the worldwide prevalence of obesity, it is highly desirable for an EIT system to produce high-quality images from obese as well as lean subjects. In EIT, the internal current density distribution and the sensitivity of a boundary voltage to a change of internal conductivity vary with respect to the current injection scheme. We quantified the range of measured boundary voltages subject to a chosen current injection scheme and investigated the influence of various obesity levels on the number of distinguishable boundary voltages given a fixed amount of system noise. We found that the 0-skip current injection scheme, where neighboring electrode pairs are used for current injections, could be most favorable to improve spatial resolution but produces the smallest number of distinguishable boundary voltages. To obtain an enough number of distinguishable boundary voltages from an obese subject, the gap between current injection electrodes should be increased depending on the circumference of a chosen imaging plane. We suggested a guideline for current injection schemes in EIT to produce images with better quality from obese as well as lean subjects.

Evaluation of indoor and outdoor air quality in university academic buildings and associated health risk

ABSTRACT Air pollution is associated with several detrimental health conditions. This study assessed comfort parameters, priority air pollutants, hydrogen sulphide (H2S), non-methane hydrocarbons (NMHCs), and volatile organic compounds (VOCs) in natural science departments in a university to understand their role in air pollutant concentrations in university environments and associated health risks. Levels of air pollutants in the departments varied. High CO2 concentrations existed in all departments with highest levels of NMHC and VOC observed in the biochemistry, microbiology and biotechnology (BMBT) department. Highest Air quality index value of 111.3 was recorded for NO2 in the BMBT department. Health risk associated with exposure to these pollutants was highest for occupants in the physiology, followed by the biodiversity, and finally BMBT department. Natural science departments seem to contribute significant amounts of H2S, NO2, NMHCs and TVOCs in university campuses. Additional ventilation and frequent monitoring of air quality in these departments are recommended.

Noninvasive Ventilation Downloads and Monitoring.

"Home noninvasive ventilation (NIV) is indicated for numerous conditions including neuromuscular disease, thoracic cage disorders, chronic obstructive pulmonary disease, and hypoventilation syndromes. Effective management of patients on home NIV requires clinicians to interpret data downloads from NIV devices. Clinicians must first look at adherence and factors that may impact this including mask comfort and fit. Next, leak assessment is undertaken. Once these are addressed, such information as apnea-hypopnea index, exhaled tidal volume, and percent triggered breaths help clinicians troubleshoot setting changes. Finally, overnight oximetry and transcutaneous CO2 monitoring are useful adjuncts to the data download to optimize NIV settings."

Ventilation and perfusion scintigraphy after lung transplantation

Study objective.Evaluation of the possibilities of ventilation and perfusion scintigraphy in detecting functional disorders and determining the severity of lung damage that may occur after organ transplantation.Material and methods.The study included 27 patients after bilateral lung transplantation; mucoviscidosis was the main cause of terminal respiratory failure in most cases (19 patients; 77.8%). The ventilation scintigraphy was performed with99mTc-pentatech using a nebulizer, and the perfusion scintigraphy was performed with99mТс-albumin macroaggregate. The investigations were performed on Infinia II and Discovery 670 NM/CT single-photon emission tomographs (GE, USA).Results.Changes in the quantitative parameters of ventilation and perfusion scintigraphy in patients after lung transplantation were studied. When analyzing the results of radionuclide studies, we identified a restoration of function after lung transplantation, and the appearance of disorders with the development of complications in the early (up to 4 months) and later (more than one year) periods after bilateral lung transplantation.Conclusion.The study has shown that the radionuclide method has wide possibilities for assessing the ventilation and perfusion functions in patients after lung transplantation, helping in the differential diagnosis of obliterating bronchiolitis and graft vascular sclerosis, in assessing the nature of alveolar-capillary diffusion disorders, and determining the extent of functional abnormalities in every individual patient. Monitoring the function of transplanted lungs using scintigraphy allows separate monitoring of ventilation and perfusion changes, which is important for the choice of treatment tactics.

EIT based intrathoracic pulsatile impedance measurements during apnea: a case study

Abstract Intrathoracic ventilation related and pulsatile (perfusion) impedance changes can be measured by the noninvasive and radiation-free imaging method Electrical Impedance Tomography (EIT). Ventilation monitoring is still the key research area in EIT, whereby perfusion monitoring gain more and more in interest. However, there are still many unknown influencing factors concerning pulsatile impedance measurements which have to be investigated. Hence, in this observational case study the impact of prolonged apnea periods on pulsatile impedance changes was examined in a patient with suspected brain death undergoing several apnea tests. In addition, the correlation between changes in pulsatile impedance and certain blood gas parameters (carbon dioxide partial pressure, pCO2; oxygen partial pressure, pO2; pH; bicarbonate, HCO3 -) were explored. Results show that the pulsatile impedance signal changes over time during apnea. An increase in the area under the curve (Mean AuC) and the maximum amplitude (Mean Max) of heart beat associated impedance signals was observed (Mean AuC: up to 65 %; Mean Max: up to 57 %). Furthermore, a positive correlation between the increase in impedance and pCO2and HCO3 - was assessed (both: up to 0.99), whereas pO2and pH show a negative correlation (both: up to -0.99). These preliminary results indicate that pulsatile EIT monitoring may be applied to get additional information regarding cardio-pulmonary interactions sustaining diagnosis or treatment of lung diseases.

Estimating regional pulmonary blood flow in EIT with regularized deconvolution with a Tikhonov regularization

Abstract Electrical Impedance Tomography (EIT) is a clinically used tool for bed-side monitoring of ventilation. Previous work also showed a high potential for lung perfusion monitoring with indicator-enhanced EIT. However, many research questions have yet to be answered before it can be broadly applied in clinical everyday life. The goal of this work is to evaluate a new method to improve EIT perfusion measurements. Pulmonary hemodynamic transfer functions were estimated using regularized deconvolution with Tikhonov regularization to estimate spatial perfusion parameters. The final comparison between EIT images and PET scans showed a median correlation of 0.897 for the images which were reconstructed using the regularized deconvolution. In comparison the previously used maximum slope method led to a median correlation of 0.868.

Monitoring lung impedance changes during long-term ventilator-induced lung injury ventilation using electrical impedance tomography

Objective: The target of this methodological evaluation was the feasibility of long-term monitoring of changes in lung conditions by time-difference electrical impedance tomography (tdEIT). In contrast to ventilation monitoring by tdEIT, the monitoring of end-expiratory (EELIC) or end-inspiratory (EILIC) lung impedance change always requires a reference measurement. Approach: To determine the stability of the used Pulmovista 500® EIT system, as a prerequisite it was initially secured on a resistive phantom for 50 h. By comparing the slopes of EELIC for the whole lung area up to 48 h from 36 pigs ventilated at six positive end-expiratory pressure (PEEP) levels from 0 to 18 cmH2O we found a good agreement (range of r2 = 0.93–1.0) between absolute EIT (aEIT) and tdEIT values. This justified the usage of tdEIT with its superior local resolution compared to aEIT for long-term determination of EELIC. Main results: The EELIC was between −0.07 Ωm day−1 at PEEP 4 and −1.04 Ωm day−1 at PEEP 18 cmH2O. The complex local time pattern for EELIC was roughly quantified by the new parameter, centre of end-expiratory change (CoEEC), in equivalence to the established centre of ventilation (CoV). The ventrally located mean of the CoV was fairly constant in the range of 42%–46% of thorax diameter; however, on the contrary, the CoEEC shifted from about 40% to about 75% in the dorsal direction for PEEP levels of 14 and 18 cmH2O. Significance: The observed shifts started earlier for higher PEEP levels. Changes of EELI could be precisely monitored over a period of 48 h by tdEIT on pigs.

Invasiveness of Treatment Is Gender Dependent in Intensive Care: Results From a Retrospective Analysis of 26,711 Cases.

Health care and outcome of critically ill patients are marked by gender-related differences. Several studies have shown that male patients in intensive care units (ICU) more often receive mechanical ventilation, dialysis, pulmonary arterial catheterization (PAC), and central venous catheterization (CVC). We investigated gender-related differences in ICU treatment and mortality. This retrospective, single-center study analyzed adult ICU patients admitted to the University Medical Center Regensburg between January 2010 and December 2017. Illness severity was measured with the Simplified Acute Physiology Score II (SAPS II) at ICU admission. We evaluated the intensity of ICU treatment according to the implementation of tracheostomy and extracorporeal membrane oxygenation (ECMO). We then assessed gender-related differences in the duration of mechanical ventilation and other invasive monitoring (PAC) and treatment methods (CVC, endotracheal intubation rate, and dialysis). ICU treatment and mortality data were obtained from an electronic data capture system. After adjusting for age, reason for hospitalization, and SAPS II score, we assessed the influence of gender on the intensity of ICU treatment using multivariable logistic regression. Odds ratios (OR) for the logistic regression models and incidence rate ratios (IRR) for the negative binomial regression models were calculated as effect estimates together with the corresponding 95% confidence intervals (95% CI). A P value of <.05 was considered significant. The study analyzed 26,711 ICU patients (64.8% men). The ICU mortality rate was 8.8%. Illness severity, ICU, and hospital mortality did not differ by gender. Women were older than men (62.6 vs 61.3 years; P < .001) at ICU admission. After multivariable adjustment, men were more likely to undergo tracheostomy (OR = 1.39 [1.26-1.54]), ECMO (OR = 1.37 [1.02-1.83]), dialysis (OR = 1.29 [1.18-1.41]), and PAC insertion (OR = 1.81 [1.40-2.33]) and had a longer duration of mechanical ventilation than women (IRR = 1.07 [1.02-1.12]). The frequency of endotracheal intubation (OR = 1.04 [0.98-1.11]) and placement of CVC (OR = 1.05 [0.98-1.11]) showed no gender-specific differences. Of ICU nonsurvivors, men were more likely to undergo tracheostomy (20.1% vs 15.3%; P = .004) and dialysis (54% vs 46.4%; P < .001) than women and had a longer duration of mechanical ventilation (6.3 vs 5.4 days; P = .015). After adjustment for severity of disease and outcome, ICU treatment differs between men and women. Men were more likely than women to undergo tracheostomy and ECMO.

Use of an Integrated Low-Flow Anesthetic Vaporizer, Ventilator, and Physiological Monitoring System for Rodents

Use of an Integrated Low-Flow Anesthetic Vaporizer, Ventilator, and Physiological Monitoring System for Rodents

Use of an Integrated Low-Flow Anesthetic Vaporizer, Ventilator, and Physiological Monitoring System for Rodents.

Low-flow digital vaporizers commonly utilize a syringe pump to directly administer volatile anesthetics into a stream of carrier gas. Per animal welfare recommendations, animals are warmed and monitored during procedures requiring anesthesia. Common anesthesia and physiological monitoring equipment include gas tanks, anesthetic vaporizers and stands, warming controllers and pads, mechanical ventilators, and pulse oximeters. A computer is also necessary for data collection and to run equipment software. In smaller spaces or when performing field work, it can be challenging to configure all this equipment in limited space. The goal of this protocol is to demonstrate best practices for use of a low-flow digital vaporizer using both compressed oxygen and room air, along with an integrated mechanical ventilator, pulse oximeter, and far infrared warming as an all-inclusive anesthesia and physiological monitoring suite ideal for rodents.

Are positive-pressure ventilation lobby rooms effective for protective and source isolation?

SUMMARYHigh-efficiency particulate air supplied to a positive-pressure ventilation lobby (PPVL) in isolation rooms offers the dual advantage of protective and source isolation. This study demonstrates the in-use validity of PPVL rooms for protective isolation of patients. Of the 48 PPVL air samples investigated, Aspergillus fumigatus was detected from only one (2%) sample. Local and remote monitoring of the PPVL rooms is essential for the safety of patients and healthcare workers. Remote and point-of-use engineering controls are essential for ongoing ventilation monitoring, but this should be complemented by visual inspection of the isolation suite. Periodic microbiological monitoring should also be considered with other control measures.

Esophageal Manometry.

The estimation of pleural pressure with esophageal manometry has been used for decades, and it has been a fertile area of physiology research in healthy subject as well as during mechanical ventilation in patients with lung injury. However, its scarce adoption in clinical practice takes its roots from the (false) ideas that it requires expertise with years of training, that the values obtained are not reliable due to technical challenges or discrepant methods of calculation, and that measurement of esophageal pressure has not proved to benefit patient outcomes. Despites these criticisms, esophageal manometry could contribute to better monitoring, optimization, and personalization of mechanical ventilation from the acute initial phase to the weaning period. This review aims to provide a comprehensive but comprehensible guide addressing the technical aspects of esophageal catheter use, its application in different clinical situations and conditions, and an update on the state of the art with recent studies on this topic and on remaining questions and ways for improvement.

Ventilation Monitoring and Control in Mines

Ventilation monitoring and control in mines are becoming an integral part of day-to-day activity for maintaining health and safety of miners. The authors evaluate potential real-time monitoring solutions for detecting and reducing diesel particulate matter, mine fires, and dust in situ, and examined the state-of-the-art use of ventilation monitoring and control in underground mines for detecting and reducing air contaminants to acceptable regulatory limit. Authors review relevant documents, including research papers, trade publications, and manufacturers’ website-based information, to identify research gaps. The authors also evaluate contemporary sensors (airflow, gas, dust, silica), control system and software technologies, data transport systems, Industrial Internet of Things, ventilation network simulators, and control devices to identify potential health and safety research gaps. In this study, examples of some mines from Canada, Australia, and the USA are included where ventilation monitoring and controls have been applied. Overall, this review identifies multiple challenges and research gaps in applying mine monitoring and control systems that could be the focus of future research, offering potential improvements to miner safety and health and financial benefits.

Frequency of hyperoxaemia during and after major surgery.

The oxygen concentration (FiO2) and arterial oxygen tension (PaO2) delivered in patients undergoing major surgery is poorly understood. We aimed to assess current practice with regard to the delivered FiO2 and the resulting PaO2 in patients undergoing major surgery. We performed a retrospective cohort study in a tertiary hospital. Data were collected prospectively as part of a larger randomised controlled trial but were analysed retrospectively. Patients were included if receiving controlled mandatory ventilation and arterial line monitoring. Anaesthetists determined the FiO2 and the oxygenation saturation (SpO2) targets. An arterial blood gas (ABG) was obtained 15-20 minutes after induction of anaesthesia, immediately before the emergence phase of anaesthesia and 15 minutes after arrival in the post-anaesthesia care unit (PACU). We defined hyperoxaemia as a PaO2 of >150 mmHg and included a further threshold of PaO2 >200 mmHg. We studied 373 patients. The median (interquartile range (IQR)) lowest intraoperative FiO2 and SpO2 values were 0.45 (IQR 0.4-0.5) and 97% (IQR 96-98%), respectively, with a median PaO2 on the first and second ABG of 237 mmHg (IQR 171-291 mmHg) and 189 mmHg (IQR 145-239 mmHg), respectively. In the PACU, the median lowest oxygen flow rate was 6 L/min (IQR 3-6 L/min), and the PaO2 was 158 mmHg (IQR 120-192 mmHg). Hyperoxaemia occurred in 82%, 73% and 54% of participants on the first and second intraoperative and postoperative ABGs respectively. A PaO2 of >200 mmHg occurred in 64%, 41% and 21% of these blood gases, respectively. In an Australian tertiary hospital, a liberal approach to FiO2 and PaO2 was most common and resulted in a high incidence of perioperative hyperoxaemia.

Electrical impedance segmentography: A promising tool for respiratory monitoring?

Non-invasive, radiation free bedside monitoring methods have gained increased popularity in the respiratory field. The aim of our study was to report the experience with electrical impedance segmentography (EIS), a rather new technique, which allows continuous visual and quantitative monitoring of regional lung ventilation. Prospective, pilot trial in spontaneously breathing, healthy, non-sedated term neonates between 24 and 72 hours post-delivery using a commercially available EIS-device. Systematic review of the literature. A total of 12 neonates were eligible for complete data analysis in our study. EIS was found to be a safe and easy to perform method. The median duration of the study time was 25 minutes (16-40). Individual total and regional impedance values, given in arbitrary units and it's percentage of distribution in the upper and lower right and left lung segments (UR, UL, LR, LL), were variable (median total impedance 207 arbitrary units (AU), UR% 17, LR 27%,UL 28%, LL 23%). A number of influencing factors such as body movements, sucking, jawing, and electrode issues have to be considered for correct data interpretation. The literature search revealed two small experimental studies in neonatal piglets and two human studies (one study in preschool children with bronchopulmonary dysplasia and one case report in a neonate with respiratory distress). EIS is an innovative technique and a potentially useful tool in studying regional lung ventilation in research and clinical care.

Real-time infrared image processing for control and monitoring of greenhouse system

Providing microclimate conditions in greenhouse systems is very important in terms of growing desired products. In addition, remote sensing and data analysis processes need to be developed and expanded to perform fast and perfect monitoring and control in these systems. An application of remote sensing with infrared imaging in greenhouse systems has been developed. It is proposed to obtain the mean temperature inside the greenhouse via infrared images, the air relative humidity with psychrometric chart application, and the soil moisture values with the multiple regression analysis method. The control and monitoring of automatic irrigation, heating, humectation, ventilation, and lighting systems were carried out via the MATLAB–GUI interface. The desired conditions for the carnation plant were ensured in the greenhouse, and 24-h data were obtained. The digital and visual application findings showed that the designed system is more advantageous in terms of ease of use, monitoring, and simultaneous recording compared with the traditional sensor control systems.

Volumetric capnography for analysis and optimization of ventilation and gas exchange

Capnography as the graphical representation of the expiratory carbon dioxide (CO2) concentration, is an essential component of monitoring of every ventilated patient, in addition to pulse oximetry. Capnography demonstrates the kinetics of CO2 in a noninvasive way and in real time. In the daily routine anesthesia, it mainly serves for identification of the correct intubation and adaptation of the respiratory minute volume to be applied; however, capnography can also provide much more far-reaching and clinically particularly valuable information, especially in the form of volumetric capnography (VCap) that is not yet so widely clinically available. These include monitoring and optimization of ventilation and assessment of gas exchange. This article presents parameters for making decisions at the bedside, which could previously only be obtained by extensive, more invasive, nonautomated procedures.

The validity of surface EMG of extra-diaphragmatic muscles in assessing respiratory responses during mechanical ventilation: A systematic review

PurposeEvidence supporting the utilization of surface EMG (sEMG) of extra-diaphragmatic muscles for monitoring of mechanical ventilation (MV) assistance is unclear. The purpose of this review was to assess the quality of literature available on using extra-diaphragmatic sEMG as an assessment technique of respiratory responses during MV. MethodsStudies using sEMG of extra-diaphragmatic respiratory muscles during MV were selected by two independent researchers after performing a database search of PubMed, CINAHL, GOOGLE SCHOLAR. Exclusion criteria were studies of patients with neuromuscular disorders, receiving neuromuscular blocking agents, receiving non-invasive MV, using needle EMG, and studies written in languages other than English. Quality of identified studies was assessed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). This study is registered with PROSPERO, number (CRD42018081341). Results596 references were identified. Of the identified studies, 7 studies were included in the review. Findings demonstrate that sEMG of extra-diaphragmatic muscle activity is a valid and applicable tool to evaluate mechanical loading/unloading of respiratory muscles and respiratory drive or sensation. However, the quality of literature supporting sEMG as monitoring tool of respiratory responses were characterized by a high and unclear risk of bias. ConclusionsAlthough it appears to be a valid and applicable tool, there is a scarcity of literature that directly demonstrates the diagnostic accuracy of sEMG of extra-diaphragmatic muscles in monitoring respiratory mechanics and respiratory drive or sensation during MV assistance across wide populations and conditions.