Dynamics of Carbon Dioxide Elimination Following Ventilator Resetting*

Taskar, Varsha; John, Joseph; Larsson, Anders; Wetterberg, T; Jonson, B.

doi:10.1378/chest.108.1.196

Cited by 66 publications

(40 citation statements)

References 22 publications

(2 reference statements)

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“…Then, during Tp20, VtCO 2 should, after the initial increase, return towards the baseline that represents metabolic rate. In patients without significant cardiopulmonary disease, when ventilation was decreased by 10%, a new steady state was established along a mono-exponential path with a time constant of ϳ35 min (17). In the present study, the return towards baseline during Tp20 was far from complete ( Fig.…”

Section: Discussionmentioning

confidence: 42%

Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury

Devaquet¹,

Jonson²,

Niklason³

et al. 2008

Journal of Applied Physiology

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Devaquet J, Jonson B, Niklason L, Si Larbi A-G, Uttman L, Aboab J, Brochard L. Effects of inspiratory pause on CO 2 elimination and arterial PCO2 in acute lung injury. J Appl Physiol 105: 1944 -1949, 2008. First published 18 September 2008 doi:10.1152/japplphysiol.90682.2008.-A high respiratory rate associated with the use of small tidal volumes, recommended for acute lung injury (ALI), shortens time for gas diffusion in the alveoli. This may decrease CO 2 elimination. We hypothesized that a postinspiratory pause could enhance CO 2 elimination and reduce PaCO 2 by reducing dead space in ALI. In 15 mechanically ventilated patients with ALI and hypercapnia, a 20% postinspiratory pause (Tp20) was applied during a period of 30 min between two ventilation periods without postinspiratory pause (Tp0). Other parameters were kept unchanged. The single breath test for CO 2 was recorded every 5 min to measure tidal CO 2 elimination (VtCO2), airway dead space (VDaw), and slope of the alveolar plateau. Pa O 2 , PaCO 2 , and physiological and alveolar dead space (V Dphys, VDalv) were determined at the end of each 30-min period. The postinspiratory pause, 0.7 Ϯ 0.2 s, induced on average Ͻ0.5 cmH 2O of intrinsic positive end-expiratory pressure (PEEP). During Tp20, VtCO 2 increased immediately by 28 Ϯ 10% (14 Ϯ 5 ml per breath compared with 11 Ϯ 4 for Tp0) and then decreased without reaching the initial value within 30 min. The addition of a postinspiratory pause significantly decreased V Daw by 14% and V Dphys by 11% with no change in VDalv. During Tp20, the slope of the alveolar plateau initially fell to 65 Ϯ 10% of baseline value and continued to decrease. Tp20 induced a 10 Ϯ 3% decrease in Pa CO 2 at 30 min (from 55 Ϯ 10 to 49 Ϯ 9 mmHg, P Ͻ 0.001) with no significant variation in Pa O 2 . Postinspiratory pause has a significant influence on CO 2 elimination when small tidal volumes are used during mechanical ventilation for ALI. gas exchange; dead space; mechanical ventilation; ARDS AFTER TRANSPORT of inspired gas through conducting airways, gas mixing in the respiratory zone by diffusion is time dependent. Therefore, a pause following gas insufflation may enhance gas exchange. Mechanical ventilators allow setting of a postinspiratory pause time (Tp), often in percent of the breathing cycle.During mechanical ventilation, prolonged Tp has been shown to enhance CO 2 elimination (8, 10 -12, 14, 21). In healthy pigs, a prolonged Tp increases CO 2 elimination per tidal breath (VtCO 2 ) by decreasing airway dead space (V Daw ) (20). It was suggested that a prolonged Tp increased the mean distribution time (MDT) of inspired gas, so as to allow more time for diffusion of CO 2 towards more central airways (7). MDT, further explained below, expresses the time available for enhanced diffusion between inhaled tidal volume and resident alveolar gas (2).In pigs at health and with acute lung injury (ALI), Aström et al. recently found that a certain prolongation of MDT achieved with a longer Tp or with a longer inspiratory insufflation ti...

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Section: Discussionmentioning

confidence: 42%

Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury

Devaquet¹,

Jonson²,

Niklason³

et al. 2008

Journal of Applied Physiology

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“…Arterial blood gas (ABG) is preferred over venous blood gas in acutely ill patients who commonly have cardiovascular dysfunction, because arterial and venous measurements correlate poorly in this population. [4][5][6] The P CO 2 in arterial blood (P aCO 2 ) reaches a new steady state approximately 10 -20 min following a change in minute ventilation, 7,8 whereas the P aO 2 attains equilibrium even faster. 9,10 Despite the importance of timely ABG measurement, there are no guidelines or published standards that promote this practice.…”

Section: See the Related Editorial On Page 996mentioning

confidence: 99%

“…This 1-h cutoff is consistent with prior studies, whose aim was to establish specific criteria for ordering ABGs. 26,27 In addition, this seemed like a reasonable threshold, given the time it takes for P aCO 2 to equilibrate following a ventilation change 7,8 and anticipated variability in specimen transport and processing time using the central laboratory offsite. Secondary outcome measures included time from initiation of mechanical ventilation to ABG result, frequency of moderate-severe acidemia on initial post-intubation ABG (defined as pH Ͻ 7.25), and frequency of respiratory acidosis.…”

Section: Main Outcome Measuresmentioning

confidence: 99%

Using a Post-Intubation Checklist and Time Out to Expedite Mechanical Ventilation Monitoring: Observational Study of a Quality Improvement Intervention

et al. 2016

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BACKGROUND: Delayed mechanical ventilation monitoring may impede recognition of lifethreatening acidemia. Coordination of multidisciplinary processes can be improved by using a checklist and time-out procedure. The study objective was to evaluate process-related outcomes after implementation of a post-intubation checklist and time out. METHODS: An observational study of a 24-bed medical ICU in Philadelphia, Pennsylvania, was conducted from January to December 2011. A random sample of mechanically ventilated adults was selected from the preintervention (n ‫؍‬ 80) and post-intervention (n ‫؍‬ 144) periods. The primary outcome was the proportion of subjects with an arterial blood gas (ABG) result within 60 min of mechanical ventilation initiation. Secondary outcomes included rates of respiratory acidosis, moderate-severe acidemia (pH <7.25), checklist initiation, and project sustainability. Chi-square analysis was used to evaluate differences in outcomes between time periods. RESULTS: After the intervention, the proportion of subjects with an ABG result within 60 min increased (56% vs 37%, P ‫؍‬ .01), and time to ABG result improved (58 min vs 79 min, P ‫؍‬ .004). Adjusting for illness severity, the proportion with an ABG result within 60 min remained significantly higher in the post-intervention period (odds ratio 2.42, 95% CI 1.25-4.68, P ‫؍‬ .009). Checklist adherence was higher with ICU intubations than for intubations performed outside the ICU (71% vs 27% checklist initiation rate, P < .001). Transfer from referring institutions (23% checklist initiation rate, P ‫؍‬ .006) negatively impacted checklist use. Implementation challenges included frequent stakeholder turnover, undefined process ownership, and lack of real-time performance feedback. CONCLUSIONS: A post-intubation checklist and time out improved the timeliness of mechanical ventilation monitoring through more rapid assessment of arterial blood gases. Implementing this peri-intubation procedure may reduce the risks associated with transitioning to full mechanical ventilatory support. Optimal implementation necessitates strategies to surmount organizational and behavioral barriers to change.

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“…Increased pulmonary dead space fraction has been shown to predict mortality in patients with the acute respiratory distress syndrome [7]. The inspiratory muscular work of breathing is proportional to the rapid shallow breathing index, which is the ratio of respiratory rate divided by tidal volume in litres, and is inversely proportional to the exhaled volume of CO 2 per minute [5,8]. Peak expiratory flow can be used to estimate expiratory airway resistance [9].…”

Section: Measurementsmentioning

confidence: 99%

Randomised controlled cross‐over comparison of continuous positive airway pressure through the Hamilton Galileo ventilator with a Dräger CF 800 device*

et al. 2004

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SummaryIn this controlled, randomised cross‐over trial on 26 intensive care patients, we compared the effects on haemodynamic and respiratory profiles of continuous positive airway pressure delivered through the Hamilton Galileo ventilator or a Dräger CF 800 device. We also compared the nursing time saved using the two approaches when weaning patients from mechanical ventilation. We did not find significant differences in haemodynamics, respiratory rate, physiological dead space, oxygen saturation and carbon dioxide production between the continuous positive airway pressure generated by the Galileo and Dräger machines. However, there was a 10‐fold reduction in nursing time using the Galileo ventilator compared with the Dräger generator. We conclude that continuous positive airway pressure delivered through the Galileo ventilator is as efficient as a Dräger device but consumes less nursing time.

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Dynamics of Carbon Dioxide Elimination Following Ventilator Resetting*

Cited by 66 publications

References 22 publications

Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury

Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury

Using a Post-Intubation Checklist and Time Out to Expedite Mechanical Ventilation Monitoring: Observational Study of a Quality Improvement Intervention

Randomised controlled cross‐over comparison of continuous positive airway pressure through the Hamilton Galileo ventilator with a Dräger CF 800 device*

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Dynamics of Carbon Dioxide Elimination Following Ventilator Resetting*

Cited by 66 publications

References 22 publications

Effects of inspiratory pause on CO2 elimination and arterial Pco2 in acute lung injury

Effects of inspiratory pause on CO2 elimination and arterial Pco2 in acute lung injury

Using a Post-Intubation Checklist and Time Out to Expedite Mechanical Ventilation Monitoring: Observational Study of a Quality Improvement Intervention

Randomised controlled cross‐over comparison of continuous positive airway pressure through the Hamilton Galileo ventilator with a Dräger CF 800 device*

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Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury

Effects of inspiratory pause on CO₂ elimination and arterial Pco₂ in acute lung injury