Pulmonary function is shown in Table 1. There was severe obstructive lung disease with an FEV/FVC ratio of 44 percent. No significant changes were noted in lung volumes or arterial blood gas measurements with the tracheostomy tube, Montgomery button, or after tracheal stoma closure. Airways resistance measured at the mouth, was very high with the fenestrated deflated tracheostomy tube in place (7.55 cm H20/L/s). It decreased by 43 percent with placement of the Montgomery button and reached its lowest value with tracheostomy stoma closure (2.94 cm H20/L/s). Exercise endurance increased by 400 percent with decannulation and stoma closure (Table 2). This was associated with an increase in minute ventilation (17.5 to 19.9 L/min) at similar oxygen uptake (8 ml/kg/min). Respiratory muscle function measured during ergometry is shown in Table 3. The Pdi max at end exercise decreased 40 percent with the tracheostomy tube in place, 27 percent with the Montgomery button, and 13 percent after tracheostomy closure. The Pdi/Pdi max recorded during exercise was reduced after stoma closure and also with the Montgomery button. The duty cycle (Ti/T tot) was highest during exercise with the tracheostomy tube in place. It was less with the Montgomery button and lowest after tracheal revision. The tension time index (Pdi/Pdi max x Ti/Ttot) was decreased after stoma closure compared to that observed with the tracheostomy tube in place. The contribution of gastric pressure to the generation of Pdi max at end exercise was greatest after removal of the tracheostomy tube.
In this patient with severe CAO and respiratory muscle dysfunction, ventilatory muscle performance, exercise endurance, and airways resistance were adversely affected by the presence of a fenestrated tracheostomy tube. All parameters improved with substitution of a Montgomery button and further with tracheal stoma closure resulting in total weaning from night time ventilatory support. Previous literature regarding complications of tracheostomy or endotracheal tube placement have focused on mechanically-induced trauma to the larynogotracheal tree. Ready to know more and more about different aspects of life it means you should be here source: canadian health care mall. The idea is to become a versatile person sounds attractevely that’s why do not waste time and go to the page using the link.
The acute consequences on respiratory muscle work with the possible induction of muscle fatigue by the increased resistance has been studied in normal subjects breathing through different diameter tubes. The consequences of increased respiratory loading by a chronic tracheostomy tube in severely obstructed patients is unclear. It has been observed that many will tolerate this load better if the tracheostomy tube is uncuffed and a fenestrae is made to decrease airflow resistance.
The ventilatory muscles in patients with CAO are subjected to increased work loads imposed by greater flow resistance, while the system is already compromised by mechanical disadvantage of the diaphragm and the accessory muscles. Farther respiratory muscle loading in these patients risks the danger of worsening respiratory muscle dysfunction and precipitating fatigue. The airways resistance created by a deflated, fenestrated tracheostomy tube is significant and proved to be a prohibitive added flow resistive load to our patient. In this case, exercise endurance improved with reduction of airways resistance, while little change was observed in resting muscle strength measured at similar lung volumes. Postexercise reductions of respiratory muscle strength were less after tracheostomy tube removal as illustrated by the Pdi max values obtained before and after exercise (Table 3). The reasons for this are reflected in measures of Pdi/Pdi max, the duty cycle (Ti/T tot), and their product, the tension time index (TO), recorded during exercise. The tension time index was more than two times higher with the tracheostomy tube in place during exercise and greater than the value of 0.15 that has been found to produce diaphragmatic fatigue in normal subjects and COPD patients during inspiratory resistive loading. Further evidence of diaphragmatic fatigue is shown by the marked loss of Pg contribution in the performance of Pdi max postexercise with the tracheostomy tube in place.
Tracheostomy tubes in ambulatory patients such as ours are frequently capped to permit speech, allow upper airway humidification of inspired air and provide for use of supplemental oxygen via nasal cannula. Tracheostomy tube size must be balanced between a diameter that is large enough to allow for adequate mechanical ventilation and small enough not to prohibitively increase airways resistance when the patient must breathe around the deflated outer cannula and through the fenestration. The fenestration of the outer cannula must be inspected for placement in the center of the upper airway to ensure optimal position. Both tracheostomy tube size and fenestration site of the outer cannula were determinated to be optimal for this patient.
We believe that a cuff deflated, fenestrated, tracheostomy tube, when capped, provides a significant increase in airways resistance that may limit respiratory muscle function in patients with compromised ventilatory reserve. Tube designs that offer less resistance or a permanent tracheostomy fistula that permits self cannulation as needed for mechanical ventilation may provide a rational approach for their management. Intermittent self cannulation of a permanent fistula would avoid added flow resistance while ambulatory and still provide access for ventilatory support.
Table 1—Pulmonary Function Studies
Table 2—Physiologic Parameters Recorded during Leg Ergometry
|Endurance time (min)||3.1||4.0||11.8|
|Minute ventilation (L/min)||17.5||19.0||19.9|
|Oxygen consumption (ml/kg/min)||8.0||8.0||8.0|
|Oxygen saturation (%)||82||82||86|
Table 3—Respiratory Muscle Function at Rest, during and After Leg Ergometry
|Pdi,,*, (cm HjO)||68||404:||80||66*||70||61*|