the patient was a 13-day - old male infant 1,350 g at birth , who was born by cesarean delivery .
pulmonary surfactant was administered via an endotracheal tube twice because of respiratory distress syndrome and the newborn was provided with mechanical ventilation for 35 hours .
the patient received oxygen by hood until the sixth day of life , and received 2.5 mg injections of aminophylline every 12 hours because of apnea diagnosed on the eighth day of life .
gavage feeding was discontinued and bile excretion was noted . before the surgery , the vital signs were stable .
there were no abnormalities on the ecg or chest x - ray . on the day of surgery ,
standard monitoring ( electrocardiogram , noninvasive blood pressure and peripheral pulse oxygen saturation ) was performed .
injection of 500 ml of 10% dextrose water + nacl 15 meq + heparin 500 iu 8 ml / hr was carried out via the internal jugular vein using a 24 gauge catheter and was maintained at 10 - 0 ml / hr during the surgery
. an 8 vol% of sevoflurane was administered and then maintained with a 3 vol% of sevoflurane .
fresh gas flow was maintained with o2 1 l / min and air 4 l / min .
injection of 1 mg of rocuronium was administered because there was no difficulty with mask ventilation .
two minutes later , intubation with a 2.0 mm i d ( internal diameter ) endotracheal tube was attempted .
the tube was checked and intubation attempted again with the same endotracheal tube , two minutes later .
the tube was fixed at 7 cm the tube was cut from 12 cm to reduce the dead space . after cutting the tube ,
there was no change in the depth ; ventilation could not be provided and there were no breath sounds . the endotracheal tube was removed and mask ventilation was provided again .
the tube was fixed at 7 cm and cut from 12 cm to reduce the dead space . after cutting the tube ,
one - lung ventilation was suspected , so manual ventilation was attempted , changing the depth of the endotracheal tube .
after the intubation , ventilation was successful and breath sounds were detected bilaterally , in addition , to regular capnography of the etco2 .
the tube was fixed at 7 cm and cut from 12 cm to reduce the dead space . however , this time the ventilation was successful .
injections with 0.05 mg of pyridostigmine and 0.01 mg of glycopyrrolate were provided and spontaneous ventilation occurred . after surgery ,
the duration for anesthesia was 2 hr 30 min and the operation was 2 hr . there was no specific change in the bp or hr .
two hours after surgery , the endotracheal tube was removed because the respirations were stable .
however , rigid bronchoscopy was not performed for confirmation , because there were no specific symptoms at that time .
cough , inspiratory stridor , and recurrent pneumonia are symptoms associated with tracheomalacia ; the most severe symptom is apnea . in most cases , symptoms improve spontaneously and patients require conservative care .
however , if severe apnea develops , recurrent pneumonia , or extubation failure , surgery is needed .
tracheomalacia is frequently associated with other congenital anomalies such as an esophageal stricture or tracheoesophageal fistula .
it is also associated with tumors that can press on the trachea , connective tissue disorders and long - term high pressure ventilator care .
common symptoms associated with a tracheoesophageal fistula include dyspnea during feeding , cyanosis , and aspiration pneumonia caused by regurgitation of food or saliva ; this can be diagnosed by failure of attempts to insert a nasogastric tube . the diagnosis is usually made immediately after birth or within 15 days of life .
the h - type of tracheoesophageal fistula , which is not associated with an esophageal stricture , may have no specific symptoms until adulthood .
however , in this case , a tracheoesophageal fistula was ruled out because the patient had gavage tube feeding and there were no specific signs on the gastrograffin test .
ventilation was not successful with a 2.0 mm i d tube or a cut 2.5 mm i d tube in this case .
the relationship between the flow , the tube and gas in a straight tube is explained by the hagen - poiseuille equation .
the hagen - poiseuille equation is as follows : v = pr4/8ul ( v = flow and  = 3.1416 , p = pressures , r = radius of tube , l = length of tube , u = viscosity of gas ) . a tube with a smaller radius has greater flow ; the flow was greatest for the 2.0 mm i d tube and slowest with the 3.0 mm i d tube .
according to the bernoulli effects , pressure decreases as the flow increases , at narrow points .
turbulent flow occurs at the end of the tube where the radius of the tube changes .
the relationship between the flow and the pressure is as follows : v  p .
it is assumed that the obstruction of the airway was caused by the pressure outside of the tube .
flow increases with the 2.0 mm i d tube more than with 3.0 mm i d tube .
the faster flow passes to the end of the tube and the pressure inside of the tube decreases when the faster flow passes the narrow point caused by the tracheomalacia . at that moment
, obstruction of the airway occurs due to pressure outside of the tube . in this case , ventilation was not successful immediately after the tube was cut to reduce the dead space when a 2.5 mm i d tube was used .
ventilation failure after cutting the tube was caused by obstruction of the airway due to a decrease in the pressure .
the decrease in pressure was caused by shortening of the length of the tube which increases the flow rate ; then , faster flow passes through the narrow segment .
reported that with a 4.0 mm i d tube , there is a 22% decrease in the resistance when the length of tube was changed to 11.3 cm from 20.7 cm .
the decrease of the pressure by 22% was associated with shortening of the length of the endotracheal tube . for endotracheal tubes smaller than the 4.0 mm i d tube
, the decrease in the radius is associated with a rapid increase in the pressure .
an increase in the gas flow from 5 l / min to 10 l / min causes an increase of pressure from 81.2 h2o / l / sec to 139.4 h2o / l / sec in a 2.5 mm i d tube while the pressure changes from 3.1 h2o / l / sec to 4.6 h2o / l / sec in a 6.0 mm i d tube . in this case , the 2.5 mm i d tube length was changed from 18 cm to 12 cm and the 3.0 mm i d tube length was changed from 19 cm to 12 cm .
the flow in the tube was not laminar flow but turbulent flow , which is not directly proportional to the pressure or length .
the decrease in pressure was 18% and 19% , each , according to the relationship between the length of laminar flow and the pressure .
disappearance of the parabola form , with turbulent flow , can lead to an increase in the pressure .
it is assumed that the decrease of pressure is lower with turbulent flow than with laminar flow . during manual ventilation ,
5 l / min was used ; however , the fresh gas flow rate was briefly more than 10 l / min .
this patient received mechanical ventilator care and oxygen hood treatment before surgery ; there were no abnormal symptoms associated with respiration .
reported that 95% of patients with tracheomalacia have no symptoms until two to three months after birth .
thus , when obstruction of the airway occurs during induction of general anesthesia , tracheomalacia should be suspected .
it is important to select the radius and length of a tube carefully when endotracheal intubation is performed in a patient with tracheomalacia .
 tracheomalacia is a malformation of the tracheal membranosa . 
 it is maintained during spontaneous breathing but can be altered by bronchoscopy or positive airway pressure . 
 tracheomalacia is associated with a high mortality and may cause prolonged intubation and ventilation . here , the case of a 13-day - old infant with jejunoileal stenosis that had surgery is reported . during induction of general anesthesia , endotracheal intubation 
 was attempted several times with different sized endotracheal tubes . 
 airway obstruction occurred after the endotracheal intubation . 
 after the airway was maintained , the operation was completed . 
 tracheomalacia was diagnosed after otolaryngology evaluation postoperatively . 
Case Report
Discussion