Tracheal Dynamics in Infants with Respiratory Distress, Stridor, and Collapsing Trachea

“…In instances of ventilatory limitation the maximal exercise ventilation (V 'Emax) will often be more than 70% MBC, which is the normal ratio in healthy individuals. In addition, it has been claimed that MBC is a sensitive index of the ventilatory limitation in UAO [3,[8][9][10][11][12][13]. It seems, however, very probable that the calculated MBC (MBCc), derived from FEV1 (e.g.…”

mentioning

confidence: 99%

Relationship between external resistances, lung function changes and maximal exercise capacity

Melissant¹,

Lammers²,

Demedts³

1998

Eur Respir J

View full text Add to dashboard Cite

The relationship between the abnormalities in the different routine lung function tests and the degree of functional limitation during exercise is not well established in upper airway obstruction (UAO). On the contrary, in chronic obstructive pulmonary disease (COPD), for instance, a forced expiratory volume in one second (FEV1) of 60% predicted is generally associated with a peak expiratory flow (PEF) of 60-70% pred and corresponds with a moderate physical impairment of ~20-30% [1,2]. Yet, in UAO, FEV1 will still be 70-80% pred when PEF is only 40-50% pred and it is not established what the clinical relevance is of each of these changes in terms of exercise limitation, although it is generally accepted that FEV1 is an insensitive test for UAO [3][4][5].In several respiratory disorders the maximal breathing capacity (MBC) is considered a useful index of the degree of ventilatory impairment because the exercise limitation shows a good relationship with the reduction in MBC [6,7]. In instances of ventilatory limitation the maximal exercise ventilation (V 'Emax) will often be more than 70% MBC, which is the normal ratio in healthy individuals. In addition, it has been claimed that MBC is a sensitive index of the ventilatory limitation in UAO [3,[8][9][10][11][12][13]. It seems, however, very probable that the calculated MBC (MBCc), derived from FEV1 (e.g. FEV1 ×37.5) will overestimate the actual ventilatory reserve in UAO, because of the already mentioned underestimation of the obstruction by FEV1. The relationship between FEV1 or MBCc and exercise capacity will, in addition, vary depending on the type of obstruction (i.e. fixed, variable extrathoracic or variable intrathoracic) because this will markedly influence the ratio of maximal expiratory over inspiratory flows [8]. Therefore, the measured MBC (MBCm) and not MBCc appears to be the appropriate MBC index in UAO, because it also reflects inspiratory besides expiratory flow rates, in contrast to MBCc [14][15][16][17]. The relationship between MBCm, MBCc, V 'Emax and exercise capacity is, however, not well established in UAO. Yet LINDSTEDT et al. [18] Therefore, we investigated in nine healthy subjects (age 36±9 yrs) the effects of two added resistances at the mouth (R1 = added resistance with 7.8 mm diameter; R2 = 5.7 mm) on forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), airway resistance (Raw) and maximal breathing capacity (measured during 15 s = measured maximum breathing capacity (MBCm); calculated as FEV1×37.5 = calculated maximum breathing capacity (MBCc)) on the one hand, and maximum exercise capacity (W 'max), minute ventilation (V 'E) and CO 2 elimination (V 'CO 2 ) on the other.We found that R1 had almost no influence on FEV1 but decreased PEF by ~35% and increased Raw by almost 300%; it decreased W 'max by merely ~10% while maximal exercise ventilation (V 'Emax) was only 65% of control and only reached ~40% MBCc and ~70% MBCm; yet V 'E and V 'CO 2 were significantly reduced at high exercise levels indicating hypoventilat...

show abstract

“…In fact, several authors have reported that continuous positive airway pressure, with or without intermittent positive pressure ventilation, alleviates tracheal collapse. [5][6][7][8] In our patient, airway obstruction occurred on several occasions and was due probably to multiple causes. Partial airway obstruction occurred during anesthesia, the obstruction worsened during emergence from anesthesia (after removal of the laryngeal mask), obstruction was not relieved temporarily after tracheal intubation and obstruction re-appeared when the patient agitated (in the presence of a tracheal tube).…”

Section: Discussionmentioning

confidence: 57%

“…A likely mechanism is that, during normal breathing, intrapleural pressure is always slightly more negative than the intratracheal pressure and, thus, the airway remains open. 5,6 However, during forced expiration (such as coughing or in the patient who needs to overcome the increased airway resistance at the level of the lower trachea (e.g., tracheobronchomalacia)) both intrapleural pressure and alveolar pressure markedly increase. Because the pressure decreases along the airway in direction of the thoracic outlet, the trachea will be subjected to a compressing transmural pressure that increases towards the thoracic outlet.…”

Section: Discussionmentioning

confidence: 99%

“…Because the pressure decreases along the airway in direction of the thoracic outlet, the trachea will be subjected to a compressing transmural pressure that increases towards the thoracic outlet. 5,6 When positive pressure is applied to the airway during forced expiration, the gradient between the intrathoracic and intratracheal pressures is reduced; therefore, tracheal collapse is, in theory, less likely to occur during controlled ventilation than during spontaneous breathing. In fact, several authors have reported that continuous positive airway pressure, with or without intermittent positive pressure ventilation, alleviates tracheal collapse.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Airway obstruction in a child with asymptomatic tracheobronchomalacia

Shingu

2001

Can J Anesth/J Can Anesth

View full text Add to dashboard Cite

Purpose: To report a case of airway obstruction with hypoxia during emergence from anesthesia due to unexpected tracheobronchomalacia in a child.Clinical features: In a previously healthy 22-month-old boy with no symptoms or signs of respiratory disease, general anesthesia was induced by inhalation of increasing concentrations of sevoflurane (up to 5%) in oxygen and a laryngeal mask was inserted. Partial airway obstruction persisted during surgery, but obstruction was relieved by positive-pressure ventilation. During emergence from anesthesia, airway obstruction with hypoxia occurred, necessitating tracheal intubation. Emission of carbon dioxide as well as of sevoflurane was reduced and emergence from anesthesia markedly delayed. Fibreoptic tracheoscopy showed marked collapse of the tracheobronchi during expiration, and a diagnosis of tracheobronchomalacia was made. No respiratory complications occurred postoperatively.Conclusion: Asymptomatic tracheomalacia should also be suspected in case of airway obstruction during anesthesia in young children.

show abstract

Tracheal Dynamics in Infants with Respiratory Distress, Stridor, and Collapsing Trachea

Cited by 153 publications

References 9 publications

Dimensions of the growing trachea related to age and gender

Dimensions of the growing trachea related to age and gender

Relationship between external resistances, lung function changes and maximal exercise capacity

Airway obstruction in a child with asymptomatic tracheobronchomalacia

Contact Info

Product

Resources

About