scholarly journals Mechanical power normalized to lung-thorax compliance predicts prolonged ventilation weaning failure: a prospective study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alessandro Ghiani ◽  
Joanna Paderewska ◽  
Swenja Walcher ◽  
Claus Neurohr
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory System ◽  
Prolonged Mechanical Ventilation ◽  
Minute Ventilation ◽  
Characteristic Curve ◽  
Mechanical Power ◽  
Likelihood Ratios ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Weaning Failure

Abstract Background Mechanical power (MP) of artificial ventilation, the energy transferred to the respiratory system, is a chief determinant of adequate oxygenation and decarboxylation. Calculated MP, the product of applied airway pressure and minute ventilation, may serve as an estimate of respiratory muscle workload when switching to spontaneous breathing. The aim of the study was to assess MP’s discriminatory performance in predicting successful weaning from prolonged tracheostomy ventilation. Methods Prospective, observational study in 130 prolonged mechanically ventilated, tracheotomized patients in a specialized weaning center. Predictive weaning outcome ability of arterial blood gas analyses and indices derived from calculated MP at beginning and end of weaning was determined in terms of area under receiver operating characteristic curve (AUROC) and measures derived from k-fold cross-validation (likelihood ratios, diagnostic odds ratio, F1 score, and Matthews correlation coefficient [MCC]). Results Forty-four (33.8%) patients experienced weaning failure. Absolute MP showed poor discrimination in predicting outcome; whereas specific MP (MP normalized to dynamic lung-thorax compliance, LTCdyn-MP) had moderate diagnostic accuracy (MCC 0.38; AUROC 0.79, 95%CI [0.71‒0.86], p < 0.001), further improved by correction for corresponding mechanical ventilation PaCO2 (termed the power index of the respiratory system [PIrs]: MCC 0.52; AUROC 0.86 [0.79‒0.92], p < 0.001). Diagnostic performance of MP indices increased over the course of weaning, with maximum accuracy immediately before completion (LTCdyn-MP: MCC 0.49; AUROC 0.86 [0.78‒0.91], p < 0.001; PIrs: MCC 0.68; AUROC 0.92 [0.86‒0.96], p < 0.001). Conclusions MP normalized to dynamic lung-thorax compliance, a surrogate for applied power per unit of ventilated lung volume, accurately discriminated between low and high risk for weaning failure following prolonged mechanical ventilation.

scholarly journals Mechanical power normalized to lung-thorax compliance indicates weaning readiness in prolonged ventilated patients

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Alessandro Ghiani ◽  
Joanna Paderewska ◽  
Swenja Walcher ◽  
Konstantinos Tsitouras ◽  
Claus Neurohr ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Logistic Regression ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Characteristic Curve ◽  
Spontaneous Breathing Trial ◽  
Mechanical Power ◽  
Binary Logistic Regression Model ◽  
Weaning Failure ◽  
Ventilated Patients

AbstractSince critical respiratory muscle workload is a significant determinant of weaning failure, applied mechanical power (MP) during artificial ventilation may serve for readiness testing before proceeding on a spontaneous breathing trial (SBT). Secondary analysis of a prospective, observational study in 130 prolonged ventilated, tracheotomized patients. Calculated MP’s predictive SBT outcome performance was determined using the area under receiver operating characteristic curve (AUROC), measures derived from k-fold cross-validation (likelihood ratios, Matthew's correlation coefficient [MCC]), and a multivariable binary logistic regression model. Thirty (23.1%) patients failed the SBT, with absolute MP presenting poor discriminatory ability (MCC 0.26; AUROC 0.68, 95%CI [0.59‒0.75], p = 0.002), considerably improved when normalized to lung-thorax compliance (LTCdyn-MP, MCC 0.37; AUROC 0.76, 95%CI [0.68‒0.83], p < 0.001) and mechanical ventilation PaCO2 (so-called power index of the respiratory system [PIrs]: MCC 0.42; AUROC 0.81 [0.73‒0.87], p < 0.001). In the logistic regression analysis, PIrs (OR 1.48 per 1000 cmH2O2/min, 95%CI [1.24‒1.76], p < 0.001) and its components LTCdyn-MP (1.25 per 1000 cmH2O2/min, [1.06‒1.46], p < 0.001) and mechanical ventilation PaCO2 (1.17 [1.06‒1.28], p < 0.001) were independently related to SBT failure. MP normalized to respiratory system compliance may help identify prolonged mechanically ventilated patients ready for spontaneous breathing.

Severe Acute Asthma in a Pediatric Intensive Care Unit: Six Years' Experience

PEDIATRICS ◽  
1989 ◽  
Vol 83 (6) ◽  
pp. 1023-1028
Author(s):  
Renato Stein ◽  
Gerard J. Canny ◽  
Desmond J. Bohn ◽  
Joseph J. Reisman ◽  
Henry Levison
Keyword(s):  
Mechanical Ventilation ◽  
Intensive Care ◽  
Severe Asthma ◽  
Acute Asthma ◽  
Mortality And Morbidity ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Oral Corticosteroids ◽  
Severe Acute Asthma ◽  
At Home

The management of children with severe acute asthma who required admission to the intensive care (ICU) of this hospital during 1982 to 1988 was reviewed retrospectively. A total of 89 children were admitted to the ICU on 125 occasions. During the study period, 24% of the patients were admitted to the ICU on more than one occasion. Prior to admission to this hospital, patients had been symptomatic for a mean of 48 hours. Although all patients had received bronchodilators before admission to hospital, only 23% of patients had received oral corticosteroids. According to initial arterial blood gas values determined in the ICU, 77% of the patients had hypercapnia (PaCO2 &gt;45 mm Hg). The pharmacologic agents used in the ICU included nebulized β2agonists (100% of admissions), theophylline (99%), steroids (94%), nebulized ipratropium bromide (10%), IV albuterol (38%), and IV isoproterenol (10%). Mechanical ventilation was necessary in 33% of admissions; the mean duration of ventilation was 32 hours. Ten patients had pneumothorax; in six cases, these were related to mechanical ventilation. Three of the patients who received mechanical ventilation died, representing a mortality of 7.5%. In each of these patients, sudden, severe asthma episodes had developed at home, resulting in respiratory arrest. They had evidence of hypoxic encephalopathy at the time of admission to the ICU and eventually were declared brain dead. It was concluded that delay in seeking medical care and underuse of oral corticosteroids at home may have contributed to the need for ICU admission. The mortality and morbidity for children with severe asthma who require ICU admissions are small, provided that bronchodilators and IV steroids are used optimally and that patients who require mechanical ventilation are carefully selected.

Ventilatory response to moderate and severe hypoxia in adult dogs: role of endorphins

1988 ◽  
Vol 65 (3) ◽  
pp. 1383-1388 ◽  
Author(s):  
J. I. Schaeffer ◽  
G. G. Haddad
Keyword(s):  
Ventilatory Response ◽  
Minute Ventilation ◽  
Severe Hypoxia ◽  
Moderate Hypoxia ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Before And After ◽  
The Relationship ◽  
Arterial Po2

To determine the role of opioids in modulating the ventilatory response to moderate or severe hypoxia, we studied ventilation in six chronically instrumented awake adult dogs during hypoxia before and after naloxone administration. Parenteral naloxone (200 micrograms/kg) significantly increased instantaneous minute ventilation (VT/TT) during severe hypoxia, (inspired O2 fraction = 0.07, arterial PO2 = 28-35 Torr); however, consistent effects during moderate hypoxia (inspired O2 fraction = 0.12, arterial PO2 = 40-47 Torr) could not be demonstrated. Parenteral naloxone increased O2 consumption (VO2) in severe hypoxia as well. Despite significant increases in ventilation post-naloxone during severe hypoxia, arterial blood gas tensions remained the same. Control studies revealed that neither saline nor naloxone produced a respiratory effect during normoxia; also the preservative vehicle of naloxone induced no change in ventilation during severe hypoxia. These data suggest that, in adult dogs, endorphins are released and act to restrain ventilation during severe hypoxia; the relationship between endorphin release and moderate hypoxia is less consistent. The observed increase in ventilation post-naloxone during severe hypoxia is accompanied by an increase in metabolic rate, explaining the isocapnic response.

scholarly journals Efficacy and Safety Testing of a COVID-19 Era Emergency Ventilator in a Healthy Rabbit Lung Model

2021 ◽  
Author(s):  
Luke A. White ◽  
Benjamin S. Maxey ◽  
Giovanni F. Solitro ◽  
Hidehiro Takei ◽  
Steven A. Conrad ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Blood Gas ◽  
Arterial Blood Gas ◽  
Arterial Partial Pressure ◽  
Arterial Blood ◽  
Emergency Ventilation ◽  
Gas Measurements ◽  
End Tidal ◽  
Spontaneously Breathing

Abstract Background: The COVID-19 pandemic revealed a substantial and unmet need for low-cost, easily accessible mechanical ventilation strategies for use in medical resource-challenged areas. Internationally, several groups developed non-conventional COVID-19 era emergency ventilator strategies as a stopgap measure when conventional ventilators were unavailable. Here, we compared our FALCON emergency ventilator in a rabbit model and compared its safety and functionality to conventional mechanical ventilation. Methods: New Zealand white rabbits (n = 5) received mechanical ventilation from either the FALCON or a conventional mechanical ventilator (Engström CarestationTM) for 1 hour each. Airflow and pressure, blood O2 saturation, end tidal CO2, and arterial blood gas measurements were measured. Additionally, gross and histological lung samples were compared to spontaneously breathing rabbits (n = 3) to assess signs of ventilator induced lung injury.Results: All rabbits were successfully ventilated with the FALCON. At identical ventilator settings, tidal volumes, pressures, and respiratory rates were similar between both ventilators, but the inspiratory to expiratory ratio was lower using the FALCON. End tidal CO2 was significantly higher on the FALCON, and arterial blood gas measurements demonstrated lower arterial partial pressure of O2 at 30 minutes and higher arterial partial pressure of CO2 at 30 and 60 minutes using the FALCON. However, when ventilated at higher respiratory rates, we observed a stepwise decrease in end tidal CO2. Poincaré plot analysis demonstrated small but significant increases in short-term and long-term variation of peak inspiratory pressure generation from the FALCON. Wet to dry lung weight and lung injury scoring between the mechanically ventilated and spontaneously breathing rabbits were similar. Conclusions: Although conventional ventilators are always preferable outside of emergency use, the FALCON ventilator safely and effectively ventilated healthy rabbits without lung injury. Emergency ventilation using accessible and inexpensive strategies like the FALCON may be useful for communities with low access to medical resources and as a backup form of emergency ventilation.

scholarly journals Effects of high-flow oxygen therapy on patients with hypoxemia after extubation and predictors of reintubation: a retrospective study based on the MIMIC-IV database

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Taotao Liu ◽  
Qinyu Zhao ◽  
Bin Du
Keyword(s):  
Mechanical Ventilation ◽  
Treatment Group ◽  
Medical Information ◽  
Characteristic Curve ◽  
Oxygenation Index ◽  
High Flow ◽  
Control Group ◽  
Severe Hypoxemia ◽  
High Flow Oxygen ◽  
Weaning Failure

Abstract Background To investigate the indications for high-flow nasal cannula oxygen (HFNC) therapy in patients with hypoxemia during ventilator weaning and to explore the predictors of reintubation when treatment fails. Methods Adult patients with hypoxemia weaning from mechanical ventilation were identified from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. The patients were assigned to the treatment group or control group according to whether they were receiving HFNC or non-invasive ventilation (NIV) after extubation. The 28-day mortality and 28-day reintubation rates were compared between the two groups after Propensity score matching (PSM). The predictor for reintubation was formulated according to the risk factors with the XGBoost algorithm. The areas under the receiver operating characteristic curve (AUC) was calculated for reintubation prediction according to values at 4 h after extubation, which was compared with the ratio of SpO2/FiO2 to respiratory rate (ROX index). Results A total of 524,520 medical records were screened, and 801 patients with moderate or severe hypoxemia when undergoing mechanical ventilation weaning were included (100 < PaO2/FiO2 ≤ 300 mmHg), including 358 patients who received HFNC therapy after extubation in the treatment group. There were 315 patients with severe hypoxemia (100 < PaO2/FiO2 ≤ 200 mmHg) before extubation, and 190 patients remained in the treatment group with median oxygenation index 166[157,180] mmHg after PSM. There were no significant differences in the 28-day reintubation rate or 28-day mortality between the two groups with moderate or severe hypoxemia (all P > 0.05). Then HR/SpO2 was formulated as a predictor for 48-h reintubation according to the important features predicting weaning failure. According to values at 4 h after extubation, the AUC of HR/SpO2 was 0.657, which was larger than that of ROX index (0.583). When the HR/SpO2 reached 1.2 at 4 h after extubation, the specificity for 48-h reintubation prediction was 93%. Conclusions The treatment effect of HFNC therapy is not inferior to that of NIV, even on patients with oxygenation index from 160 to 180 mmHg when weaning from ventilator. HR/SpO2 is more early and accurate in predicting HFNC failure than ROX index.

scholarly journals Clinical factors associated with weaning failure in patients requiring prolonged mechanical ventilation

2017 ◽  
Vol 9 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Hong-Joon Shin ◽  
Jin-Sun Chang ◽  
Seong Ahn ◽  
Tae-Ok Kim ◽  
Cheol-Kyu Park ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Prolonged Mechanical Ventilation ◽  
Clinical Factors ◽  
Factors Associated ◽  
Weaning Failure

Management of four arterial blood gas problems in adult mechanical ventilation: decision-making algorithms and rationale for their use

1996 ◽  
Vol 16 (3) ◽  
pp. 62-73
Author(s):  
JM Anderson
Keyword(s):  
Mechanical Ventilation ◽  
Mechanical Ventilators ◽  
Acid Base Balance ◽  
Acid Base ◽  
Arterial Blood Gas ◽  
Learning Framework ◽  
Arterial Blood ◽  
Adequate Understanding ◽  
Base Balance ◽  
Reference Tool

Use of these algorithms does not eliminate the need to think. One must always evaluate each patient to determine if the algorithms are applicable. The algorithms provide a learning framework for any practitioner who is responsible for managing patients receiving mechanical ventilation. The effectiveness of any reference tool depends, to an extent, on the context in which it is applied. The use of these algorithms without an adequate understanding of the principles of gas exchange, acid-base balance, and the function of mechanical ventilators will probably not benefit the patient or the practitioner. The portable nature of these algorithms allows them to be used in the clinical setting. The ultimate goal, of course, is to replace the algorithms with the ability to make and justify mechanical ventilation decisions. Experience with these algorithms will also assist users in applying this approach with unfamiliar problems to find viable solutions.

Measurement and analysis of gas exchange during exercise using a programmable calculator

1980 ◽  
Vol 49 (3) ◽  
pp. 456-461 ◽  
Author(s):  
D. Y. Sue ◽  
J. E. Hansen ◽  
M. Blais ◽  
K. Wasserman
Keyword(s):  
Gas Exchange ◽  
Respiratory Exchange Ratio ◽  
Minute Ventilation ◽  
Co2 Production ◽  
O2 Consumption ◽  
Exercise Tests ◽  
Programmable Calculator ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
End Tidal

Although exercise testing is useful in the diagnosis and management of cardiovascular and pulmonary diseases, a rapid comprehensive method for measurement of ventilation and gas exchange has been limited to expensive complex computer-based systems. We devised a relatively inexpensive, technically simple, and clinically oriented exercise system built around a desktop calculator. This system automatically collects and analyzes data on a breath-by-breath basis. Our calculator system overcomes the potential inaccuracies of gas exchange measurement due to water vapor dilution and mismatching of expired flow and gas concentrations. We found no difference between the calculator-derived minute ventilation, CO2 production, O2 consumption, and respiratory exchange ratio and the values determined from simultaneous mixed expired gas collections in 30 constant-work-rate exercise studies. Both tabular and graphic displays of minute ventilation, CO2 production, O2 consumption, respiratory exchange ratio, heart rate, end-tidal O2 tension, end-tidal CO2 tension, and arterial blood gas value are included for aid in the interpretation of clinical exercise tests.

Effect of metabolic rate on ventilatory roll-off during hypoxia

1994 ◽  
Vol 76 (6) ◽  
pp. 2310-2314 ◽  
Author(s):  
W. M. Gershan ◽  
H. V. Forster ◽  
T. F. Lowry ◽  
M. J. Korducki ◽  
A. L. Forster ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Minute Ventilation ◽  
Face Mask ◽  
Co2 Production ◽  
O2 Consumption ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Series Of Experiments ◽  
Carotid Arterial ◽  
Arterial Po2

This study was done to determine 1) whether goats demonstrate the roll-off phenomenon, i.e., a secondary decrease in minute ventilation (VE), after an initial hyperventilation during various levels of hypoxia and, if so, 2) whether roll-off could be due to changes in metabolic rate. We hypothesized that roll-off occurs in the goat during hypoxia but is not due to hypometabolism. To answer question 1, eight unanesthetized adult goats were exposed to 15–20 min of hypoxia at 0.15, 0.12, and 0.09 inspired O2 fraction (FIO2), resulting in 60, 40, and 30 Torr arterial PO2, respectively. Goats were fitted with a face mask connected to a spirometer to measure VE, and arterial blood gas samples were obtained via carotid arterial catheters. Roll-off was seen with 0.15 and 0.12 FIO2, whereas VE steadily increased with 0.09 FIO2. During hypoxia, arterial PCO2 fell 2, 3, and 7 Torr at 0.15, 0.12, and 0.09 FIO2, respectively. In the second series of experiments, nine different goats were exposed to 30 min of 0.12 FIO2. O2 consumption and CO2 production were measured five times during baseline and hypoxia. VE increased to 32% above baseline values after 2 min of hypoxia and then gradually decreased by 18%. Changes in breathing frequency and tidal volume contributed to the roll-off. O2 consumption decreased (P = 0.0029, analysis of variance) and CO2 production increased (P = 0.0027) during hypoxia, although both changes were small (< 7%) compared with the eventual 18% decrease in VE. We conclude that the adult goat demonstrates the roll-off phenomenon during moderate levels of hypoxia. (ABSTRACT TRUNCATED AT 250 WORDS)

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