Heat and moisture exchangers and heated humidifiers in acute lung injury/acute respiratory distress syndrome patients. Effects on respiratory mechanics and gas exchange

Morán, Indalecio; Bellapart, Judith; Vari, Alessandra; Mancebo, Jordi

doi:10.1007/s00134-006-0073-1

Cited by 41 publications

(35 citation statements)

References 38 publications

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“…This intervention has been shown to be effective to reduce PaCO 2 while ventilating ARDS patients with a low Vt strategy [11,21]. Although some authors have suggested that HMEFs should be avoided during ventilation with a Vt of 6 ml/kg [22], this is not a standard practice, and furthermore, several ICUs keep using HMEFs in mechanically ventilated ARDS patients [23,24]. In the present study we kept the HMEF during ventilation with Vt 6, as was the usual practice in our ICU, but we removed it during ventilation with Vt 4.…”

Section: Discussionmentioning

confidence: 99%

Preliminary study of ventilation with 4 ml/kg tidal volume in acute respiratory distress syndrome: feasibility and effects on cyclic recruitment - derecruitment and hyperinflation

et al. 2013

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IntroductionCyclic recruitment-derecruitment and overdistension contribute to ventilator-induced lung injury. Tidal volume (Vt) may influence both, cyclic recruitment-derecruitment and overdistension. The goal of this study was to determine if decreasing Vt from 6 to 4 ml/kg reduces cyclic recruitment-derecruitment and hyperinflation, and if it is possible to avoid severe hypercapnia.MethodsPatients with pulmonary acute respiratory distress syndrome (ARDS) were included in a crossover study with two Vt levels: 6 and 4 ml/kg. The protocol had two parts: one bedside and other at the CT room. To avoid severe hypercapnia in the 4 ml/kg arm, we replaced the heat and moisture exchange filter by a heated humidifier, and respiratory rate was increased to keep minute ventilation constant. Data on lung mechanics and gas exchange were taken at baseline and after 30 minutes at each Vt (bedside). Thereafter, a dynamic CT (4 images/sec for 8 sec) was taken at each Vt at a fixed transverse region between the middle and lower third of the lungs. Afterward, CT images were analyzed and cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration, and hyperinflation as maximal hyperinflated tissue at end-inspiration, expressed as % of lung tissue weight.ResultsWe analyzed 10 patients. Decreasing Vt from 6 to 4 ml/kg consistently decreased cyclic recruitment-derecruitment from 3.6 (2.5 to 5.7) % to 2.9 (0.9 to 4.7) % (P <0.01) and end-inspiratory hyperinflation from 0.7 (0.3 to 2.2) to 0.6 (0.2 to 1.7) % (P = 0.01). No patient developed severe respiratory acidosis or severe hypercapnia when decreasing Vt to 4 ml/kg (pH 7.29 (7.21 to 7.46); PaCO2 48 (26 to 51) mmHg).ConclusionsDecreasing Vt from 6 to 4 ml/kg reduces cyclic recruitment-derecruitment and hyperinflation. Severe respiratory acidosis may be effectively prevented by decreasing instrumental dead space and by increasing respiratory rate.

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Section: Discussionmentioning

confidence: 99%

Preliminary study of ventilation with 4 ml/kg tidal volume in acute respiratory distress syndrome: feasibility and effects on cyclic recruitment - derecruitment and hyperinflation

et al. 2013

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“…[26][27][28] 4.3 When providing humidification to patients with low tidal volumes, such as when lung-protective ventilation strategies are used, HMEs are not recommended because they contribute additional dead space, which can increase the ventilation requirement and P aCO 2 . 25 4.3.1 Artificial airway dead-space reduction allows a significant P aCO 2 reduction that is independent of any respiratory mechanical changes.…”

Section: 2mentioning

confidence: 99%

Humidification During Invasive and Noninvasive Mechanical Ventilation: 2012

2012

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When the upper airway is bypassed during invasive mechanical ventilation, humidification is necessary to prevent hypothermia, disruption of the airway epithelium, bronchospasm, atelectasis, and airway obstruction. In severe cases, inspissation of airway secretions may cause occlusion of the endotracheal tube. 1 While there is not clear consensus on whether or not additional heat and humidity are always necessary when the upper airway is not bypassed, such as in noninvasive mechanical ventilation (NIV), active humidification is highly suggested to improve comfort. [2][3][4][5][6][7] Two systems, active humidification through a heated humidifier (HH) and passive humidification through a heat and moisture exchanger (HME), are available for warming and humidifying gases delivered to mechanically ventilated patients. There are 3 types of HME or artificial nose: hydrophobic, hygroscopic, and a filtered HME.Heated humidifiers operate actively to increase the heat and water vapor content of inspired gas. 8 HMEs operate passively by storing heat and moisture from the patient's exhaled gas and releasing it to the inhaled gas. 9 The upper airway provides 75% of the heat and moisture supplied to the alveoli. When bypassed, the humidifier needs to supply this missing heat and moisture. Since The authors have disclosed a relationship with Teleflex Medical, which manufactures humidification devices.

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“…Many other strategies have also been developed to decrease hypercapnia at the bedside, such as increases in respiratory rate [8], use of active humidifiers [9] and the tracheal gas insufflation [10] or aspiration of dead space [11]. At bedside, the dead space could be calculated using the Enghoff modification of the Bohr equation.…”

Section: Introductionmentioning

confidence: 99%

End-inspiratory pause prolongation in acute respiratory distress syndrome patients: effects on gas exchange and mechanics

Aguirre-Bermeo

Morán

Bottiroli

et al. 2016

Ann. Intensive Care

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BackgroundEnd-inspiratory pause (EIP) prolongation decreases dead space-to-tidal volume ratio (Vd/Vt) and PaCO2. We do not know the physiological benefits of this approach to improve respiratory system mechanics in acute respiratory distress syndrome (ARDS) patients when mild hypercapnia is of no concern.MethodsThe investigation was conducted in an intensive care unit of a university hospital, and 13 ARDS patients were included. The study was designed in three phases. First phase, baseline measurements were taken. Second phase, the EIP was prolonged until one of the following was achieved: (1) EIP of 0.7 s; (2) intrinsic positive end-expiratory pressure ≥1 cmH2O; or (3) inspiratory–expiratory ratio 1:1. Third phase, the Vt was decreased (30 mL every 30 min) until PaCO2 equal to baseline was reached. FiO2, PEEP, airflow and respiratory rate were kept constant.ResultsEIP was prolonged from 0.12 ± 0.04 to 0.7 s in all patients. This decreased the Vd/Vt and PaCO2 (0.70 ± 0.07 to 0.64 ± 0.08, p < 0.001 and 54 ± 9 to 50 ± 8 mmHg, p = 0.001, respectively). In the third phase, the decrease in Vt (from 6.3 ± 0.8 to 5.6 ± 0.8 mL/Kg PBW, p < 0.001) allowed to decrease plateau pressure and driving pressure (24 ± 3 to 22 ± 3 cmH2O, p < 0.001 and 13.4 ± 3.6 to 10.9 ± 3.1 cmH2O, p < 0.001, respectively) and increased respiratory system compliance from 29 ± 9 to 32 ± 11 mL/cmH2O (p = 0.001). PaO2 did not significantly change.ConclusionsProlonging EIP allowed a significant decrease in Vt without changes in PaCO2 in passively ventilated ARDS patients. This produced a significant decrease in plateau pressure and driving pressure and significantly increased respiratory system compliance, which suggests less overdistension and less dynamic strain.

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Heat and moisture exchangers and heated humidifiers in acute lung injury/acute respiratory distress syndrome patients. Effects on respiratory mechanics and gas exchange

Abstract: Reducing dead space with the use of HH decreases PaCO2 and more importantly, if isocapnic conditions are maintained by reducing Vt, this strategy improves respiratory system compliance and reduces plateau airway pressure.

Cited by 41 publications

References 38 publications

Preliminary study of ventilation with 4 ml/kg tidal volume in acute respiratory distress syndrome: feasibility and effects on cyclic recruitment - derecruitment and hyperinflation

Preliminary study of ventilation with 4 ml/kg tidal volume in acute respiratory distress syndrome: feasibility and effects on cyclic recruitment - derecruitment and hyperinflation

Humidification During Invasive and Noninvasive Mechanical Ventilation: 2012

End-inspiratory pause prolongation in acute respiratory distress syndrome patients: effects on gas exchange and mechanics

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