scholarly journals Computational simulation to assess patient safety of uncompensated COVID-19 two-patient ventilator sharing using the Pulse Physiology Engine

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242532
Author(s):  
Jeffrey B. Webb ◽  
Aaron Bray ◽  
Philip K. Asare ◽  
Rachel B. Clipp ◽  
Yatin B. Mehta ◽  
...  
Keyword(s):  
Patient Outcome ◽  
Oxygen Saturation ◽  
Saturation Index ◽  
Computational Simulation ◽  
Lung Compliance ◽  
Lung Mechanics ◽  
Whole Body ◽  
Arterial Oxygen ◽  
Single Patient ◽  
Primary Model

Background The COVID-19 pandemic is stretching medical resources internationally, sometimes creating ventilator shortages that complicate clinical and ethical situations. The possibility of needing to ventilate multiple patients with a single ventilator raises patient health and safety concerns in addition to clinical conditions needing treatment. Wherever ventilators are employed, additional tubing and splitting adaptors may be available. Adjustable flow-compensating resistance for differences in lung compliance on individual limbs may not be readily implementable. By exploring a number and range of possible contributing factors using computational simulation without risk of patient harm, this paper attempts to define useful bounds for ventilation parameters when compensatory resistance in limbs of a shared breathing circuit is not possible. This desperate approach to shared ventilation support would be a last resort when alternatives have been exhausted. Methods A whole-body computational physiology model (using lumped parameters) was used to simulate each patient being ventilated. The primary model of a single patient with a dedicated ventilator was augmented to model two patients sharing a single ventilator. In addition to lung mechanics or estimation of CO2 and pH expected for set ventilation parameters (considerations of lung physiology alone), full physiological simulation provides estimates of additional values for oxyhemoglobin saturation, arterial oxygen tension, and other patient parameters. A range of ventilator settings and patient characteristics were simulated for paired patients. Findings To be useful for clinicians, attention has been directed to clinically available parameters. These simulations show patient outcome during multi-patient ventilation is most closely correlated to lung compliance, oxygenation index, oxygen saturation index, and end-tidal carbon dioxide of individual patients. The simulated patient outcome metrics were satisfactory when the lung compliance difference between two patients was less than 12 mL/cmH2O, and the oxygen saturation index difference was less than 2 mmHg. Interpretation In resource-limited regions of the world, the COVID-19 pandemic will result in equipment shortages. While single-patient ventilation is preferable, if that option is unavailable and ventilator sharing using limbs without flow resistance compensation is the only available alternative, these simulations provide a conceptual framework and guidelines for clinical patient selection.

scholarly journals Computational Simulation to Assess Patient Safety of Uncompensated COVID-19 Two-patient Ventilator Sharing Using the Pulse Physiology Engine

2020 ◽  
Author(s):  
Jeffrey B. Webb ◽  
Aaron Bray ◽  
Philip K. Asare ◽  
Rachel B. Clipp ◽  
Yatin B. Mehta ◽  
...  
Keyword(s):  
Patient Outcome ◽  
Mechanical Ventilation ◽  
Oxygen Saturation ◽  
Saturation Index ◽  
Computational Simulation ◽  
Lung Compliance ◽  
Arterial Oxygen ◽  
Single Patient ◽  
Multiple Patients ◽  
Ventilator Settings

AbstractBackgroundThe COVID-19 pandemic is stretching medical resources internationally, including creating ventilator short-ages that complicate clinical and ethical situations. The possibility of needing to ventilate multiple patients with a single ventilator raises patient health and safety concerns. This simulation study explores patient compatibility and ventilator settings during multi-patient ventilation without the use of flow compensating resistances.MethodsA whole-body computational physiology model was used to simulate each patient on a ventilator. The primary model of a single patient with a dedicated ventilator was augmented to model two patients sharing a single ventilator. A range of ventilator settings and patient characteristics were simulated for paired patients. In addition to mechanical ventilation parameters, the full physiological simulation provides estimates of additional values for oxyhemoglobin saturation, arterial oxygen tension, and other patient parameters.FindingsThese simulations show patient outcome during multi-patient ventilation is most closely correlated to lung compliance, oxygenation index, oxygen saturation index, and endtidal carbon dioxide of individual patients. The simulated patient outcome metrics were satisfactory when the lung compliance difference between two patients was less than 12 cmH2O/mL, and the oxygen saturation index difference was less than 2 mmHg.InterpretationIn resource-limited regions of the world, the COVID-19 pandemic will result in equipment shortages. While single-patient ventilation is preferable, if unavailable, these simulations provide a conceptual framework for clinical patient selection guidelines if ventilator sharing is the only available alternative.FundingKitware employees were internally supported by Kitware. Bucknell and Geisinger participants contributed their time.Research in ContextEvidence before this studyIf numbers of patients requiring mechanical ventilation exceed the number of available ventilators in a surge, shared branched ventilator circuits have been proposed for sharing one ventilator by multiple patients. Only rudimentary laboratory or clinical studies have been reported. Testing over expected ranges of lung-chest wall compliance has not been found. Few clinical experiences of mechanical ventilation parameters employed for COVID-19 patients have been reported.Added value of this studyThe number of possible combinations of ventilation and physiological parameters is very large. Time and resource constraints do not permit conventional research. Computational simulation provides rapid sensitivity evaluation of several factors over a wide range of hypothetical ventilation conditions. Envelopes of evaluated parameters may provide reasonably estimated safety boundaries for clinicians compelled in an emergency surge to employ a poorly characterized practice. A previously well-vetted computational model for ventilation of a single patient by a dedicated ventilator has been modified to model the sharing of a single ventilator by two or more patients. Only pairings of two equally sized 70 kg patients are modeled in this report. These simulations provide estimates of effects on ventilation and blood oxygenation by clinically measurable values using conceivable mismatched patient lung compliance and oxygenation (diffusion and shunt).Implications of all the available evidenceThese estimates are for pressure mode ventilation using a single ventilator shared by branched breathing apparatus for paired patients. Individual patient flow restriction to compensate for compliance mismatch is not considered. Reasonable though arbitrary bounds of acceptable parameters may guide clinicians when determining pairings of patients with different physiological characteristics. Further laboratory testing and clinical experience will be needed to determine the validity or utility of these assessments. Different simulations will be needed for flow-compensated branches, more than two patients, and unmatched body habitus.

scholarly journals Estratificación de la gravedad del síndrome de distrés respiratorio agudo en pediatría.

2019 ◽  
Vol 11 (3) ◽  
pp. 3
Author(s):  
Rubén Ferreras Vega
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Risk Stratification ◽  
Respiratory Distress ◽  
Oxygen Saturation ◽  
Saturation Index ◽  
Invasive Mechanical Ventilation ◽  
Consensus Conference ◽  
Arterial Oxygen ◽  
Strong Agreement

El síndrome de distrés respiratorio agudo pediátrico (SDRAP) es una entidad propia y diferenciada del adulto. En el año 2.015, se llegó a un consenso en la conferencia Pediatric Acute Lung Injury Consensus Conference (PALICC); dónde se realizan distintas recomenciones según el acuerdo llegado entre sus integrantes. Así, para la estratificación de la gravedad del SDRAP, en pacientes en ventilación mecánica invasiva (VMI), se utiliza el índice de oxigenación (IO). En su defecto, si no es posible obtener la PaO2, utilizaremos el índice de saturación.  ABSTRACT Risk Stratification in pediatric acute respiratory distress syndrome Is necessary to make a diference between adults and children in acute respiratory distress sydrome. Different concepts have been introduced and modified. However, it was not until 2015, at the Acute Lung Injury Consensus Conference (PALICC) (1), when pediatric acute respiratory distress sydrome (PARDS) has been recognized as an entity well differentiated from adults. Acording to PALICC agreement, some recomendations about risk stratification in PARDS for patients receiving invasive mechanical ventilation, must be followed. Instead of Pao2/Fio2 ratio, It is recommended the use of oxygenation index (OI = ([Fio2 × mean airway pressure (Paw) × 100]/Pao2)), in order to know PARDS severity (strong agreement). When arterial oxygen pressure (Pa o2) is not avalible, oxygen saturation index (OSI= ([Fio2 × Paw × 100]/Spo2)) can be used (strong agreement). Based on these recommendations, mild PARDS is defined as an OI of 4–8 (oxygen saturation index = 5–7.5), moderate as an OI of 8–16 (oxygen saturation index = 7.5–12.3), and severe as an OI > 16 (oxygen saturation index > 12.3).  

Effects of age on pulmonary perfusion heterogeneity measured by magnetic resonance imaging

2007 ◽  
Vol 102 (5) ◽  
pp. 2064-2070 ◽  
Author(s):  
David L. Levin ◽  
Richard B. Buxton ◽  
James P. Spiess ◽  
Tatsuya Arai ◽  
Jamal Balouch ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Oxygen Saturation ◽  
Signal Intensity ◽  
Arterial Oxygen Saturation ◽  
Relative Dispersion ◽  
Whole Body ◽  
Arterial Oxygen ◽  
Pulmonary Perfusion ◽  
Resonance Imaging

Normal aging is associated with a decline in pulmonary function and efficiency of gas exchange, although the effects on the spatial distribution of pulmonary perfusion are poorly understood. We hypothesized that spatial pulmonary perfusion heterogeneity would increase with increasing age. Fifty-six healthy, nonsmoking subjects (ages 21–76 yr) underwent magnetic resonance imaging with arterial spin labeling (ASL) using a Vision 1.5-T whole body scanner (Siemens Medical Systems, Erlangen, Germany). ASL uses a magnetically tagged bolus to generate perfusion maps where signal intensity is proportional to regional pulmonary perfusion. The spatial heterogeneity of pulmonary blood flow was quantified by the relative dispersion (RD = SD/mean, a global index of heterogeneity) of signal intensity for voxels within the right lung and by the fractal dimension ( Ds). There were no significant sex differences for RD ( P = 0.81) or Ds ( P = 0.43) when age was considered as a covariate. RD increased significantly with increasing age by ∼0.1/decade until age 50–59 yr, and there was a significant positive relationship between RD and age ( R = 0.48, P < 0.0005) and height ( R = 0.39, P < 0.01), but not body mass index ( R = 0.07, P = 0.67). Age and height combined in a multiple regression were significantly related to RD ( R = 0.66, P < 0.0001). There was no significant relationship between RD and spirometry or arterial oxygen saturation. Ds was not related to age, height, spirometry, or arterial oxygen saturation. The lack of relationship between age and Ds argues against an intrinsic alteration in the pulmonary vascular branching with age as being responsible for the observed increase in global spatial perfusion heterogeneity measured by the RD.

Lung mechanics and resuscitation after fluid aspiration

1961 ◽  
Vol 16 (4) ◽  
pp. 684-696 ◽  
Author(s):  
H. J. H. Colebatch ◽  
D. F. J. Halmagyi
Keyword(s):  
Sea Water ◽  
Arterial Oxygen Saturation ◽  
Lung Compliance ◽  
Lung Mechanics ◽  
Arterial Oxygen ◽  
Intratracheal Administration ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Before And After ◽  
Pulmonary Capillary Blood

Lung mechanics, arterial oxygen saturation (Sao2) and effective pulmonary capillary blood flow (Qe) were measured before and after intratracheal administration of 1—3 ml/kg body wt. of fresh or sea water in 20 intact and 11 vagotomized sheep during light thiopentone anesthesia. A gross fall in lung compliance (Cl) occurred in all animals after introduction of fresh and sea water; the fall was greater in intact than in vagotomized animals. A variable increase in nonelastic resistance was mainly due to blocking of airways by fluid and foam. Fall in Cl appeared to be the consequence of a reaction within the lungs resulting in a widespread closure of the terminal airways, which was influenced by the vagus nerve but not abolished by vagotomy. By relating Cl and Qe, hypoxemia induced by fluid was explained in terms of altered lung mechanics. Forced inflation increased Cl after fresh water and to a greater extent in vagotomized animals, but produced no change after sea water. A method of resuscitation is suggested based on the change in lung mechanics. With the use of 100% oxygen this method restored normal Sao2 independent of amount of fluid in the lung. Submitted on December 28, 1960

Leptin attenuates respiratory complications associated with the obese phenotype

1998 ◽  
Vol 85 (6) ◽  
pp. 2261-2269 ◽  
Author(s):  
C. G. Tankersley ◽  
C. O’Donnell ◽  
M. J. Daood ◽  
J. F. Watchko ◽  
W. Mitzner ◽  
...  
Keyword(s):  
Breathing Pattern ◽  
Minute Ventilation ◽  
Gene Replacement ◽  
Lung Compliance ◽  
Protein Product ◽  
Lung Mechanics ◽  
Whole Body ◽  
Respiratory Complications ◽  
Genetic Mouse Model ◽  
Obese Phenotype

A profile of respiratory complications has been associated with the onset and development of obesity in humans. Similar phenotypes have been routinely demonstrated in genetic animal models of obesity such as the ob mouse (C57BL/6J- Lepob ). The objective of the present study was to test the hypothesis that a constellation of respiratory complications are attenuated with leptin (i.e., protein product of the ob gene) replacement. Daily leptin administration during a 6-wk period was conducted to control body weight of mutant ob mice similar to genotypic control groups. During the treatment period, repeated baseline ventilatory measurements were assessed by using whole body plethysmography while quasistatic pressure-volume curves were performed to further explore the role of leptin in improving lung mechanics. Diaphragmatic myosin heavy chain (MHC) isoform phenotype was examined to determine proportional changes in MHC composition. In room air, breathing frequency and minute ventilation were significantly ( P < 0.01) different among ob treatment groups, suggesting that leptin opposed the development of a rapid breathing pattern observed in vehicle-treated ob mice. Quasistatic deflation curves indicated that the lung volume of leptin-treated ob mice was significantly ( P < 0.05) greater relative to vehicle-treated ob mice at airway pressures between 0 and 30 cmH2O. Diaphragm MHC composition of leptin-treated ob mice was restored significantly ( P < 0.05) to resemble the control phenotype. In this genetic mouse model of obesity, the results suggested that respiratory complications associated with the obese phenotype, including rapid breathing pattern at baseline, diminished lung compliance, and abnormal respiratory muscle adaptations, are attenuated with prolonged leptin treatment.

scholarly journals A Combined Hot and Hypoxic Environment during Maximal Cycling Sprints Reduced Muscle Oxygen Saturation: A Pilot Study

2021 ◽  
pp. 684-689
Author(s):  
Keiichi Yamaguchi ◽  
Tomohiro Imai ◽  
Haruka Yatsutani ◽  
Kazushige Goto
Keyword(s):  
Oxygen Saturation ◽  
Near Infrared ◽  
Saturation Index ◽  
Arterial Oxygen Saturation ◽  
Muscle Oxygenation ◽  
Arterial Oxygen ◽  
Vastus Lateralis Muscle ◽  
Muscle Oxygen ◽  
Hypoxic Environment ◽  
Significant Difference

The present study investigated the effects of a combined hot and hypoxic environment on muscle oxygenation during repeated 15-s maximal cycling sprints. In a single-blind, cross-over study, nine trained sprinters performed three 15-s maximal cycling sprints interspersed with 7-min passive recovery in normoxic (NOR; 23℃, 50%, FiO2 20.9%), normobaric hypoxic (HYP; 23℃, FiO2 14.5%), and hot normobaric hypoxic (HH; 35℃, FiO2 14.5%) environments. Relative humidity was set to 50% in all trials. The vastus lateralis muscle oxygenation was evaluated during exercise using near-infrared spectroscopy. The oxygen uptake (VO2) and arterial oxygen saturation (SpO2) were also monitored. There was no significant difference in peak or mean power output among the three conditions. The reduction in tissue saturation index was significantly greater in the HH (-17.0 ± 2.7%) than in the HYP (-10.4 ± 2.8%) condition during the second sprint (p < 0.05). The average VO2 and SpO2 were significantly lower in the HYP (VO2 = 980 ± 52 mL/min, SpO2 = 82.9 ± 0.8%) and HH (VO2 = 965 ± 42 mL/min, SpO2 = 83.2 ± 1.2%) than in the NOR (VO2 = 1149 ± 40 mL/min, SpO2 = 90.6 ± 1.4%; p < 0.05) condition. In conclusion, muscle oxygen saturation was reduced to a greater extent in the HH than in the HYP condition during the second bout of three 15-s maximal cycling sprints, despite the equivalent hypoxic stress between HH and HYP.

scholarly journals Accuracy of two pulse-oximetry measurements for INTELLiVENT-ASV in mechanically ventilated patients: a prospective observational study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinshu Katayama ◽  
Jun Shima ◽  
Ken Tonai ◽  
Kansuke Koyama ◽  
Shin Nunomiya
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Prospective Observational Study ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Arterial Blood Gas ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Arterial Blood ◽  
Ventilated Patients

AbstractRecently, maintaining a certain oxygen saturation measured by pulse oximetry (SpO2) range in mechanically ventilated patients was recommended; attaching the INTELLiVENT-ASV to ventilators might be beneficial. We evaluated the SpO2 measurement accuracy of a Nihon Kohden and a Masimo monitor compared to actual arterial oxygen saturation (SaO2). SpO2 was simultaneously measured by a Nihon Kohden and Masimo monitor in patients consecutively admitted to a general intensive care unit and mechanically ventilated. Bland–Altman plots were used to compare measured SpO2 with actual SaO2. One hundred mechanically ventilated patients and 1497 arterial blood gas results were reviewed. Mean SaO2 values, Nihon Kohden SpO2 measurements, and Masimo SpO2 measurements were 95.7%, 96.4%, and 96.9%, respectively. The Nihon Kohden SpO2 measurements were less biased than Masimo measurements; their precision was not significantly different. Nihon Kohden and Masimo SpO2 measurements were not significantly different in the “SaO2 < 94%” group (P = 0.083). In the “94% ≤ SaO2 < 98%” and “SaO2 ≥ 98%” groups, there were significant differences between the Nihon Kohden and Masimo SpO2 measurements (P < 0.0001; P = 0.006; respectively). Therefore, when using automatically controlling oxygenation with INTELLiVENT-ASV in mechanically ventilated patients, the Nihon Kohden SpO2 sensor is preferable.Trial registration UMIN000027671. Registered 7 June 2017.

scholarly journals COVID-19 ARDS is characterized by higher extravascular lung water than non-COVID-19 ARDS: the PiCCOVID study

Critical Care ◽  
2021 ◽  
Vol 25 (1) ◽  
Author(s):  
Rui Shi ◽  
Christopher Lai ◽  
Jean-Louis Teboul ◽  
Martin Dres ◽  
Francesca Moretto ◽  
...  
Keyword(s):  
Extravascular Lung Water ◽  
Transpulmonary Thermodilution ◽  
Diffuse Alveolar Damage ◽  
Lung Mechanics ◽  
Arterial Oxygen ◽  
Prone Positioning ◽  
University Hospitals ◽  
Lung Water ◽  
Pulmonary Vascular Permeability ◽  
Water Index

Abstract Background In acute respiratory distress syndrome (ARDS), extravascular lung water index (EVLWi) and pulmonary vascular permeability index (PVPI) measured by transpulmonary thermodilution reflect the degree of lung injury. Whether EVLWi and PVPI are different between non-COVID-19 ARDS and the ARDS due to COVID-19 has never been reported. We aimed at comparing EVLWi, PVPI, respiratory mechanics and hemodynamics in patients with COVID-19 ARDS vs. ARDS of other origin. Methods Between March and October 2020, in an observational study conducted in intensive care units from three university hospitals, 60 patients with COVID-19-related ARDS monitored by transpulmonary thermodilution were compared to the 60 consecutive non-COVID-19 ARDS admitted immediately before the COVID-19 outbreak between December 2018 and February 2020. Results Driving pressure was similar between patients with COVID-19 and non-COVID-19 ARDS, at baseline as well as during the study period. Compared to patients without COVID-19, those with COVID-19 exhibited higher EVLWi, both at the baseline (17 (14–21) vs. 15 (11–19) mL/kg, respectively, p = 0.03) and at the time of its maximal value (24 (18–27) vs. 21 (15–24) mL/kg, respectively, p = 0.01). Similar results were observed for PVPI. In COVID-19 patients, the worst ratio between arterial oxygen partial pressure over oxygen inspired fraction was lower (81 (70–109) vs. 100 (80–124) mmHg, respectively, p = 0.02) and prone positioning and extracorporeal membrane oxygenation (ECMO) were more frequently used than in patients without COVID-19. COVID-19 patients had lower maximal lactate level and maximal norepinephrine dose than patients without COVID-19. Day-60 mortality was similar between groups (57% vs. 65%, respectively, p = 0.45). The maximal value of EVLWi and PVPI remained independently associated with outcome in the whole cohort. Conclusion Compared to ARDS patients without COVID-19, patients with COVID-19 had similar lung mechanics, but higher EVLWi and PVPI values from the beginning of the disease. This was associated with worse oxygenation and with more requirement of prone positioning and ECMO. This is compatible with the specific lung inflammation and severe diffuse alveolar damage related to COVID-19. By contrast, patients with COVID-19 had fewer hemodynamic derangement. Eventually, mortality was similar between groups. Trial registration number and date of registration ClinicalTrials.gov (NCT04337983). Registered 30 March 2020—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04337983.

scholarly journals Artificial intelligence matches subjective severity assessment of pneumonia for prediction of patient outcome and need for mechanical ventilation: a cohort study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shadi Ebrahimian ◽  
Fatemeh Homayounieh ◽  
Marcio A. B. C. Rockenbach ◽  
Preetham Putha ◽  
Tarun Raj ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Patient Outcome ◽  
Mechanical Ventilation ◽  
Oxygen Saturation ◽  
Laboratory Data ◽  
Qualitative Assessment ◽  
Smoking History ◽  
Lung Edema ◽  
Strong Positive Correlation ◽  
Wbc Count

AbstractTo compare the performance of artificial intelligence (AI) and Radiographic Assessment of Lung Edema (RALE) scores from frontal chest radiographs (CXRs) for predicting patient outcomes and the need for mechanical ventilation in COVID-19 pneumonia. Our IRB-approved study included 1367 serial CXRs from 405 adult patients (mean age 65 ± 16 years) from two sites in the US (Site A) and South Korea (Site B). We recorded information pertaining to patient demographics (age, gender), smoking history, comorbid conditions (such as cancer, cardiovascular and other diseases), vital signs (temperature, oxygen saturation), and available laboratory data (such as WBC count and CRP). Two thoracic radiologists performed the qualitative assessment of all CXRs based on the RALE score for assessing the severity of lung involvement. All CXRs were processed with a commercial AI algorithm to obtain the percentage of the lung affected with findings related to COVID-19 (AI score). Independent t- and chi-square tests were used in addition to multiple logistic regression with Area Under the Curve (AUC) as output for predicting disease outcome and the need for mechanical ventilation. The RALE and AI scores had a strong positive correlation in CXRs from each site (r2 = 0.79–0.86; p < 0.0001). Patients who died or received mechanical ventilation had significantly higher RALE and AI scores than those with recovery or without the need for mechanical ventilation (p < 0.001). Patients with a more substantial difference in baseline and maximum RALE scores and AI scores had a higher prevalence of death and mechanical ventilation (p < 0.001). The addition of patients’ age, gender, WBC count, and peripheral oxygen saturation increased the outcome prediction from 0.87 to 0.94 (95% CI 0.90–0.97) for RALE scores and from 0.82 to 0.91 (95% CI 0.87–0.95) for the AI scores. AI algorithm is as robust a predictor of adverse patient outcome (death or need for mechanical ventilation) as subjective RALE scores in patients with COVID-19 pneumonia.

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