Partial Obstruction Of Endotracheal Tube Research Articles

Partial endotracheal tube obstruction by a blood clot in two dogs

Case 1: A seven-year-old lurcher presented after an episode of severe respiratory distress and collapse, which had been treated by the referring veterinary surgeon with a tracheostomy tube placement. Laryngeal...

Detection of partial endotracheal tube obstruction by forced pressure oscillations

Rapid airway occlusions during mechanical ventilation are followed immediately by high-frequency pressure oscillations. To answer the question if the frequency of forced pressure oscillations is an indicator for partial obstruction of the endotracheal tube (ETT) we performed mathematical simulations and studies in a ventilated physical lung model. Model-derived predictions were evaluated in seven healthy volunteers. Partial ETT obstruction was mimicked by decreasing the inner diameter (ID) of the ETT. In the physical model ETTs of different ID were used. In spontaneously breathing volunteers viscous fluid was applied into the ETT's lumen. According to the predictions derived from mathematical simulations, narrowing of the ETT's ID from 9.0 to 7.0mm decreased the frequency of the pressure oscillations by 11% while changes of the respiratory system's compliance had no effect. In volunteers, a similar reduction (10.9%) was found when 5 ml fluid were applied. We conclude that analysis of pressure oscillations after flow interruption offers a tool for non-invasive detection of partial ETT obstruction.

Change in Expiratory Flow Detects Partial Endotracheal Tube Obstruction in Pressure-Controlled Ventilation

Only extreme degrees of endotracheal tube (ETT) narrowing can be detected with monitoring of tidal volume (V(T)) during pressure-controlled ventilation (PCV). To assess the degree of ETT obstruction in PCV and to compare it to V(T) monitoring, we produced 3 levels of partial ETT obstruction in 11 healthy anesthetized piglets using ETTs of 4 different inner diameters (IDs 9.0, 8.0, 7.0, and 6.0 mm). An expiratory flow over volume ((e)-V) curve was plotted and the time constant (tau(e)) at 15% of expiration time (T(e)) was calculated. We also calculated the fractional volume expired during the first 15% of T(e) (V(ex fract,15)) and compared those variables to full expiratory V(T) for each of the 3 obstructions. V(T) monitoring failed to detect ETT narrowing. By contrast, V(ex fract,15) decreased and tau(e) increased significantly with increasing ETT narrowing (for IDs 9.0, 8.0, 7.0, and 6.0, mean V(ex fract,15) was 195, 180, 146, and 134 mL respectively and mean tau(e) was 380, 491, 635, 794 ms for IDs 9.0, 8.0, 7.0, and 6.0 respectively). We conclude that when the elastic recoil that drives (e) is appropriately considered, analysis of (e) and V(ex fract,15) detects partial ETT obstruction during PCV.

Peak Airway Pressure Increase Is a Late Warning Sign of Partial Endotracheal Tube Obstruction Whereas Change in Expiratory Flow Is an Early Warning Sign

If peak inspiratory airway pressure (Ppeak) is used to monitor airway patency, progressive obstruction of the endotracheal tube (ETT) resulting from secretions can go undetected for a prolonged period. The reason is that any increase in Ppeak depends not only on the degree of narrowing but also on the inspiratory flow () rate. Although the impact of narrowing on low inspiratory is small, its decelerating effect on the high expiratory is pronounced and, hence, easily detectable. Dividing the volume-flow curve of a passive expiration into five consecutive segments (slices) and calculating the time constants (tau(Epsilon)) of these slices allows for analyzing whether and how expiratory is impeded by a partial obstruction. In nine piglets, during volume-controlled ventilation, three grades of ETT obstruction were created with an external clamp. In all animals the tau(E) increased with ETT obstruction (mean for the first slice: 550 ms with unobstructed ETT; grade 1: 661; grade 2: 877; and grade 3: 1563 ms, respectively) and this increase was significant with grade 2 and 3 obstruction. Ppeak, by contrast, did not increase significantly (base: 13, grade 1: 14, grade 2: 15 cm H(2)O) until the most severe (grade 3: 20 cm H(2)O) obstruction was created. We conclude that partial obstruction of the ETT can be reliably monitored with the expiratory V signal and has the potential of monitoring ETT narrowing in ventilator-dependent patients independent of the inspiratory pattern applied.

Partial Airway Obstruction with an Armored Tube by Swelling of the Inner Layer

An Armored tube is known to be the most effective in maintaining of airway patency during anesthesia in any position. Unfortunately, the tube itself may become the cause of airway obstruction. One of the known complications of the armored tube is a separation of the individual latex layers. This can be caused by herniation into the lumen. Diffusion of nitrous oxide into the inner hernia considerably intensifies the obstruction. The bubbles in the tube wall arise during manufacturing as well as during resterilization. A 62-year-old man with herniation of lumbar disc herniation was intubated with a 8.0 mm armored tube for general anesthesia. 30 minutes later, we experienced signs of partial endotracheal tube obstruction including high arterial and inspiratory pressure in prone position. Then, tube suction with catheter was done and signs was slightly improved. But, 90 minutes later, passage of suction catheter was impossible. When operation was finished, patient was turned to supine position. We exchanged the tube with another tube and found inner wall herniation into the armored tube lumen caused by layer separation.

Partial Endotracheal Tube Obstruction Due to Secretions: A case report

Endotracheal tube obstruction causes serious complications, including cardiovascular instability, pneumothorax, pulmonary edema and brain death. A 64 year old man was scheduled for a laminectomy and instrument fixation due to spinal stenosis. The patient was intubated with a 8.5 mm reinforced endotracheal tube and turned to the prone position. An hour later, signs of partial endotracheal obstruction were observed including high airway pressure and low tidal volume. Airway obstruction signs were aggravated as the operation proceeded. Two hour later, passage of a suction catheter was difficult and PaCO2 increased significantly, so we temporarily stopped the operation and turned the patient to supine. After that, we exchanged the tube with another tube and found the distal tip of the reinforced tube impacted with mucous secretions.

Partial Obstruction of Endotracheal Tubes in Children. Incidence, Etiology, Significance

We examined 99 endotracheal tubes removed from 81 pediatric patients to determine the incidence of partial endotracheal tube obstruction and predisposing factors. The overall incidence of obstruction was 20.2% (20/99); 14 of the 20 obstructed tubes were occluded less than 50%. General anesthesia during the period of intubation was the only factor significantly associated with an increased incidence of obstruction (p less than 0.05). There was no correlation of obstruction with duration of intubation, the presence of a Murphy-eye side hole, or small tube size. Among the 71 tubes from patients who received general anesthesia, a tube size of 4 mm or less was associated with an increased incidence of obstruction (p less than 0.05). Pressure-flow curves for three different sizes of endotracheal tubes were constructed to determine the increase in resistance produced by different degrees of obstruction. At flow rates that approximated those found in children during quiet breathing, the resistance of tubes that were 50% obstructed was 4 times greater than that found in unobstructed tubes.

Partial obstruction of endotracheal tubes in children: incidence, etiology, significance.

We examined 99 endotracheal tubes removed from 81 pediatric patients to determine the incidence of partial endotracheal tube obstruction and predisposing factors. The overall incidence of obstruction was 20.2% (20/99); 14 of the 20 obstructed tubes were occluded less than 50%. General anesthesia during the period of intubation was the only factor significantly associated with an increased incidence of obstruction (p less than 0.05). There was no correlation of obstruction with duration of intubation, the presence of a Murphy-eye side hole, or small tube size. Among the 71 tubes from patients who received general anesthesia, a tube size of 4 mm or less was associated with an increased incidence of obstruction (p less than 0.05). Pressure-flow curves for three different sizes of endotracheal tubes were constructed to determine the increase in resistance produced by different degrees of obstruction. At flow rates that approximated those found in children during quiet breathing, the resistance of tubes that were 50% obstructed was 4 times greater than that found in unobstructed tubes.

Intraluminal Partial Obstruction of Endotracheal Tube due to Cuff Ballooning

Intraluminal Partial Obstruction of Endotracheal Tube due to Cuff Ballooning