Increasing respiratory rate to improve CO2 clearance during mechanical ventilation is not a panacea in acute respiratory failure*

Vieillard‐Baron, Antoine; Prin, Sébastien; Augarde, Roch; P, Desfonds; Page, Bernard; Beauchet, Alain; Jardin, François

doi:10.1097/00003246-200207000-00001

Cited by 82 publications

(57 citation statements)

References 17 publications

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“…11,[17][18][19][20][21] Indeed, this recommendation makes sense when maintaining a relatively constant V T . 15,22 However, our study demonstrates that the MFV strategy allows the clinician to provide higher frequencies. More importantly, our data are in keeping with data generated from neonatal studies in which conventional ventilation applied at higher breathing frequencies with pressure control ventilation (similar to MFV) led to improved ventilation outcomes.…”

Section: Discussionmentioning

confidence: 72%

“…¶ Rate-related de-recruitment I:E ϭ inspiratory-expiratory ratio T I ϭ inspiratory time PIP ϭ peak inspiratory pressure above atmospheric pressure P ETCO2 ϭ end-tidal P CO2 MV ϭ minute ventilation (exhaled) CV ϭ conventional ventilation NA ϭ not applicable Conventional practice limits frequency due to concerns about the development of auto-PEEP and its adverse hemodynamic effects. 10,15,16 However, MFV is different from conventional CMV with regard to the development of frequency-related auto-PEEP. In conventional ventilation, when keeping all variables constant and increasing frequency, auto-PEEP rises exponentially to very high values, but only slightly in MFV.…”

Section: Discussionmentioning

confidence: 98%

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Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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BACKGROUND: Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (V T ). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. METHODS: This was a prospective study of 6 live Yorkshire pigs (10 ؎ 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with V T ‫؍‬ 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured P aCO 2 , P aO 2 , end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. RESULTS: The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower V T (؊1 ؎ 0.7 mL/kg) and higher frequency (32.1 ؎ 6.8 vs 55.7 ؎ 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ؎ 1.3 vs 16.4 ؎ 2 cm H 2 O, P ‫؍‬ .75) even when auto-PEEP was higher (0.6 ؎ 0.9 vs 2.4 ؎ 1.1 cm H 2 O, P ‫؍‬ .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. CONCLUSIONS: In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower V T than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 98%

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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“…61 The alveolar minute ventilation range within the normal to highest limits of set ventilator breathing frequency will be as follows: V E ϭ (V T Ϫ V D ) ϫ f; V E ϭ (6 mL/kg Ϫ 2 mL/kg) ϫ 10 -35 breaths/min; V E ϭ 40 -140 mL/kg/min; V E for a 70-kg man ϭ 2.8 -9.8 L/min. 62 Now, consider COPD or even acute lung injury where V D is elevated or sepsis and metabolic acidosis, where the metabolic demand requires a higher V E . 63,64 If we increase the dead space, just by 1 mL/kg, the maximum minute ventilation that the ventilator can safely deliver decreases by 25%: V E ϭ (6 mL/kg Ϫ 3 mL/kg) ϫ 10 -35 breaths/ min; V E ϭ 30 -105 mL/kg/min; V E for a 70-kg man ϭ 2.1-7.4 L/min.…”

Section: Introduction Of the Con Positionmentioning

confidence: 99%

Should A Tidal Volume of 6 mL/kg Be Used in All Patients?

2016

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It has been shown that mechanical ventilation by itself can cause lung injury and affect outcomes. Ventilator-induced lung injury is associated with high tidal volumes in lungs afflicted with ARDS. However, the question is: Do high tidal volumes have this same effect in normal lungs or lungs that have respiratory compromise stemming from something other than ARDS? Many clinicians believe that a tidal volume strategy of 6 mL/kg predicted body weight should be standard practice in all patients receiving mechanical ventilation. There is a growing body of evidence related to this issue, and this is the debate that will be tackled in this paper from both pro and con perspectives. Key words: tidal volume; predicted body weight; mechanical ventilation; lung-protective ventilation; time constant; ARDS; stress; strain; hypercapnia. [Respir Care 2016;61(6):774 -790 . © 2016 Daedalus Enterprises] IntroductionIt is well known that the use of mechanical ventilation has the potential to aggravate pulmonary injury, but emerging evidence indicates that it may also precipitate lung injury in patients with no previous injury. Lung-protective ventilation has evolved over the past couple of decades to the point that it has become standard of care for patients with ARDS. The use of lower tidal volume (V T ) 4 -8 mL/kg predicted body weight (PBW) is part of this lung-protective strategy for mechanical ventilation (mechanical ventilation) along with limiting the plateau pressure to a maximum of 30 cm H 2 O and prudent use of PEEP to prevent atelectasis. Since we now know that the use of lower V T strategies (more specifically 6 mL/kg PBW) helps to limit the pulmonary damage during ARDS, the question now is: Should we be using this strategy in all mechanically ventilated patients? Anatomically speaking, it makes sense to, since the normal physiologic V T for humans is approximately 6 mL/kg PBW. 1 There is a growing body of evidence that points toward the use of lower V T values leading to improved outcomes in patients suffering from other forms and degrees of respiratory failure. The aim of this paper is to examine the evidence relating to the use of lower V T values in conditions other than ARDS in which mechanical ventilation is required. This will be done with viewpoints from both the pro and con positions. Early StudiesThere is a plethora of preclinical evidence from animal studies supporting the fact that the use of high V T values can directly cause injury to normal lungs. Animal studies have shown that high V T ventilation increases levels of pro-inflammatory mediators, leads to pulmonary edema, and causes increased alveolar-capillary permeability and structural abnormalities. [2][3][4][5][6][7][8] With the emergence of these animal data, clinicians began to question the traditional use of V T values in the range of 10 -15 mL/kg PBW in humans. Several small human studies were reported in the mid-to late 1990s that produced conflicting results. 9-11 These studies were hampered by several factors, including higher than predicte...

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“…This finding was interpreted as the result of an excessive respiratory rate under mechanical ventilation, leading to an expiratory time insufficient for a complete exhalation, despite a likely normal time constant. In ARDS patients, several studies have illustrated the frequency of diffuse dynamic hyperinflation produced by an excessive respiratory rate [3,4,5]. In the same manner, use of an inverse inspiratory/expiratory ratio also produces dynamic hyperinflation [6].…”

Section: Diffuse Expiratory Flow Limitationmentioning

confidence: 99%

The issue of dynamic hyperinflation in acute respiratory distress syndrome patients

Vieillard-Baron¹,

Jardin²

2003

Eur Respir J

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Dynamic hyperinflation is produced by a diffuse expiratory flow limitation impairing exhalation under mechanical ventilation. It constitutes a serious clinical problem in patients exhibiting bronchial asthma or chronic obstructive pulmonary disease, when mechanical ventilation is required. But this phenomenon may also complicate respiratory support in acute respiratory distress syndrome (ARDS) patients.The presence of diffuse airflow limitation in ARDS patients has sometimes been noticed in the past, but its consequences have only recently been emphasised in a dynamic study, using bedside recording of flow/volume loops during respiratory support.More recently, by recording systematically a prolonged expiration, the current authors have observed a localised airflow limitation in a majority of ARDS patients, constituting another potential factor of dynamic hyperinflation under respiratory support. In the same report, the current authors' have emphasised the impact of this limitation on the shape of the pressure/volume loop.At a time when increasing respiratory support is proposed to improve carbon dioxide clearance in acute respiratory distress syndrome submitted to protective ventilation, dynamic hyperinflation may become a major clinical problem in this setting.

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Increasing respiratory rate to improve CO2 clearance during mechanical ventilation is not a panacea in acute respiratory failure*

Abstract: We conclude that a high respiratory rate strategy during mechanical ventilation in patients with acute respiratory failure did not improve CO2 clearance, produced dynamic hyperinflation, and impaired right ventricular ejection.

Cited by 82 publications

References 17 publications

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

Should A Tidal Volume of 6 mL/kg Be Used in All Patients?

The issue of dynamic hyperinflation in acute respiratory distress syndrome patients

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