Intrapulmonary Gas Trapping during Mechanical Ventilation at Rapid Frequencies

Bergman, Norman A.

doi:10.1097/00000542-197212000-00011

Cited by 57 publications

(28 citation statements)

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“…If the energy potential stored during inflation is insufficient to return the system to a relaxed equilibrium before the next inspiration begins, flow continues throughout expiration and alveolar pressure remains positive at end-expiration, exceeding the clinician-selected PEEP value. [47][48][49][50][51] This unintended supplemental positive distending pressure within the alveoli at end expiration (auto-PEEP also known as intrinsic PEEP [PEEPi]) both increases the driving pressure for expiratory airflow and augments recoil, thereby helping to overcome airflow resistance. The need to hyperinflate is generated by a long expiratory time constant (mathematically, the product of expiratory resistance and compliance), increased ventilation requirements, and inadequate exhalation time.…”

Section: Dynamic Hyperinflation (Air Trapping)mentioning

confidence: 99%

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Marini

2013

Respir Care

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SummaryRelatively little attention has been directed toward damage inflicted upon the airway network that connects the alveoli, or toward the problems caused by invasive ventilation for patients with severe airflow obstruction. Mechanical ventilation with positive pressure can cause non-edematous barotrauma, inflict airway injury, and promote lung remodeling. Interactions between patient and ventilator, largely mediated through dynamic hyperinflation, include functional consequences for hemodynamics, respiratory muscle function, breathing work load, and patient-ventilator synchrony. Awareness of such associations not only helps to avoid complications during and after the critical phase of obstructive illness, but also opens a window to improved patient comfort and safety. The purpose of this review is to survey the range of structural damages and functional impairments that occur in an "obstructive" context.

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Section: Dynamic Hyperinflation (Air Trapping)mentioning

confidence: 99%

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Marini

2013

Respir Care

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“…7 Furthermore, persistent inspiratory effort after pressure support ceases can lead to double-triggering, 7 resulting in discomfort, elevated tidal volumes (V T ), and volutrauma. 8 Cycling after the end of inspiratory effort shortens the expiratory time, causing intrinsic PEEP 9 and leading to increased work of breathing during triggering of the next breath. 10,11 SEE THE RELATED EDITORIAL ON PAGE 122 In former generations of ventilators, cycling criteria were fixed, usually to 25% of peak inspiratory flow.…”

Section: Introductionmentioning

confidence: 99%

“…4,5,[9][10][11] This problem is highlighted in patients with COPD 4,12 due to the long time constant. [9][10][11] In modern ventilators, cycling can be adjusted. 4 As has been shown for invasive ventilation, adjustment of cycling criteria improves patient ventilator synchronization and reduces intrinsic PEEP.…”

Section: Introductionmentioning

confidence: 99%

Patient-Ventilator Interaction During Noninvasive Ventilation in Simulated COPD

et al. 2015

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BACKGROUND: During noninvasive ventilation (NIV) of COPD patients, delayed off-cycling of pressure support can cause patient ventilator mismatch and NIV failure. This systematic experimental study analyzes the effects of varying cycling criteria on patient-ventilator interaction. METHODS: A lung simulator with COPD settings was connected to an ICU ventilator via helmet or face mask. Cycling was varied between 10 and 70% of peak inspiratory flow at different breathing frequencies (15 and 30 breaths/min) and pressure support levels (5 and 15 cm H 2 O) using the ventilator's invasive and NIV mode with and without an applied leakage. RESULTS: Low cycling criteria led to severe expiratory cycle latency. Augmenting off-cycling reduced expiratory cycle latency (P < .001), decreased intrinsic PEEP, and avoided non-supported breaths. Setting cycling to 50% of peak inspiratory flow achieved best synchronization. Overall, using the helmet interface increased expiratory cycle latency in almost all settings (P < .001). Augmenting cycling from 10 to 40% progressively decreased expiratory pressure load (P < .001). NIV mode decreased expiratory cycle latency compared with the invasive mode (P < .001). CONCLUSION: Augmenting the cycling criterion above the default setting (20 -30% peak inspiratory flow) improved patient ventilator synchrony in a simulated COPD model. This suggests that an individual approach to cycling should be considered, since interface, level of pressure support, breathing frequency, and leakage influence patient-ventilator interaction and thus need to be considered.

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“…During high-frequency ventilation (HFV), an increase in alveolar pressure will follow when the expiratory time becomes too short for the alveolar pressure to fall to the preset end-expiratory level [1][2][3]. As a consequence, lung volume and alveolar pressure will increase until a new equilibrium is established between insufflation and expiration [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

mentioning

confidence: 99%

“…As a consequence, lung volume and alveolar pressure will increase until a new equilibrium is established between insufflation and expiration [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In previous studies we obtained evidence that such an increase in lung volume suppresses spontaneous breathing activity in piglets [17,18].…”

mentioning

confidence: 99%

Alveolar pressure during high-frequency jet ventilation

1990

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Abstract. We studied the influence of ventilatory frequency (1 -5 Hz), tidal volume, lung volume and body position on the end-expiratory alveolar-to-tracheal pressure difference during high-frequency jet ventilation (HFJV) in Yorkshire piglets. The animals were anesthetized and paralysed. Alveolar pressure was estimated with the clamp off method, which was performed by a computer controlled ventilator and which had been extensively tested on its feasibility. The alveolar-to-tracheal pressure difference increased with increasing frequency and with increasing tidal volume, the common determinant appearing to be the mean expiratory flow. The effects in prone and in supine position were similar. Increasing thoracic volume decreased the alveolar-to-tracheal pressure difference indicating a dependence of this pressure difference on airway resistance. We concluded that the main factors determining the alveolar-to-tracheal pressure difference (AP) during HFJV are expiratory flow (V'~) and airway resistance (R), AP = V'~ • R.

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Intrapulmonary Gas Trapping during Mechanical Ventilation at Rapid Frequencies

Cited by 57 publications

References 0 publications

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Patient-Ventilator Interaction During Noninvasive Ventilation in Simulated COPD

Alveolar pressure during high-frequency jet ventilation

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