An Interesting Case
A Case of an Unexpected Airway Difficulty in the Cardiac Operating Room
By Premal Trivedi MD; and Courtney Hardy, MD
Childrens Memorial Hospital, Chicago, IL
Pre-operative evaluation
The patient is a 3 month old female presenting for open repair of symptomatic atrial and ventricular septal defects (ASD, VSD). These findings, as well as the presence of a persistent left superior vena cava (SVC), were diagnosed prenatally on fetal echocardiography. The patient was born via an uneventful vaginal delivery following induction for intrauterine growth retardation. She remained in the NICU for 3 days for feeding immaturity, needing no ventilatory or oxygen support, and was subsequently discharged home on full oral feedings.
At 13 days of life, the patient was noted to develop marked tachypnea with respiratory rates in the 70s associated with grunting. The tachypnea was thought to be worse with feeding, and the patient was also noted to have intermittent emesis with feeds. She was directed to our cardiology clinic where workup revealed unlabored mild tachypnea and evidence of pulmonary overcirculation based on chest x-ray (CXR) with increased vascular markings. Given the known septal defects with their left to right shunting, and evidence of pulmonary overcirculation on CXR, the patient was started on furosemide 1 mg/kg BID.
Over the next two months, the patient was seen routinely in cardiology clinic, and her dose of furosemide was titrated up with increases in weight and persistence of tachypnea. She was also started on ranitidine and pantoprazole for presumed gastroesophageal reflux, and this regimen improved her post-prandial emesis. Of note, she never developed diaphoresis, stridor, or wheezing.
Because of the unchanged nature of her tachypnea and concerns of increasing fatigue in spite of diuretic therapy, in conjunction with the findings on echocardiography and CXR, it was decided to pursue an early repair of her ASD and VSD.
A preoperative transthoracic echocardiography performed under general anesthesia with an LMA 1 revealed:
- Fenestrated secundum ASD and large membranous VSD with left to right flow
- Left SVC to dilated coronary sinus
- Preserved left ventricular (LV) size and function
- Preserved right ventricular (RV) function, with mild dilation and hypertrophy
- RV systolic pressure 63 mmHg
- Bilateral peripheral pulmonary stenosis, peak gradient 41 mmHg across the left pulmonary artery (PA) and 27 mmHg across the right PA
Interestingly, the patient had no respiratory difficulties that were noted under general anesthesia while breathing spontaneously with the LMA.
Intraoperative events
The patient was brought to the OR and underwent an uneventful inhalational induction. Intubation was initially attempted with a 3.5 cuffed endotracheal tube (ETT), and as difficulty was met, the ETT was downsized progressively to a 3.0 uncuffed ETT. Final placement was only a few millimeters beyond the vocal cords.
Because of this unanticipated difficulty, ENT was then consulted to perform a direct laryngoscopy and bronchoscopy (DLB). Their exam revealed complete tracheal rings extending from the second tracheal ring to just proximal to the carina as well as the presence of a tracheal right upper lobe. The airway in the stenosed area was estimated to be 3 mm in diameter. A 3.0 uncuffed ETT was replaced and secured with care, and we proceeded. Because of the urgent nature of the DLB, no preoperative images were captured, but the images below demonstrates the typical appearance of complete tracheal rings compared to a normal trachea.
Left: complete tracheal rings; Right: a normal trachea with anterior cartilaginous
rings with a membranous posterior
Intraoperative TEE demonstrated the known persistent left SVC, ASD, and VSD, with unchanged ventricular function. Images obtained are below.
A transverse collar incision was made together with a traditional median sternotomy, and the patient’s trachea was partially mobilized prior to initiating cardiopulmonary bypass (CPB). Following aortic and bicaval cannulation, cardiopulmonary bypass was initiated followed by completion of tracheal mobilization. An aortic cross clamp was then placed, and the atrial and ventricular septal defects were repaired. The 8 mm ASD was repaired with suture and the 6 mm VSD was repaired with a gluteraldehyde tanned pericardial patch. The aortic cross clamp was then removed and attention was shifted to the repair of the CTS.
The overall length of the stenosis was 4.5 cm with a total of 20 complete tracheal rings. After the repair, the upper trachea admitted a 6 mm dilator, representing a 100% increase from baseline. Total length of the slide tracheoplasty was 2.5 to 3 cm. Following the repair, we evaluated for a leak by progressively increasing airway pressure to 35 cm H20. After we determined no leak, the ETT was placed in the middle of the repair.
Total time on CPB was 165 minutes with a cross clamp time of 44 min. Liberation from CPB was uneventful on the inotropes milrinone and dopamine. Post-procedure echocardiography demonstrated no residual atrial or ventricular shunting, satisfactory ventricular function with no regional wall motion abnormalities, and very mild tricuspid regurgitation. Ventilation became inadequate, however, as the increased airway diameter now caused a significant air leak with the 3.0 uncuffed ETT. To address the leak, we changed the ETT to a 3.5 uncuffed using a tube exchanger to minimize neck extension and strain on the anastomosis.
Postoperative Course
The patient was taken to the PICU intubated, and was ultimately extubated on post-operative day (POD) 6 to high flow nasal cannula, and transitioned to room air shortly thereafter. A DLB performed on POD 14 demonstrated intact suture lines with minimal granulation tissue and mild nonobstructive tracheomalacia, and repeat DLB on POD 44 demonstrated again a patent airway. The images below are taken from the DLB on POD 44. The patient was seen shortly after discharge in the cardiac surgery clinic where it was noted that her tachypnea had resolved, and that she had no signs of residual airway obstruction.
Discussion
Congenital tracheal stenosis (CTS) encompasses those lesions that result in a narrowing of the tracheal lumen, most commonly due to complete tracheal rings. This condition is rare, occurring with an incidence of approximately 1 in 64,500 patients, and representing 0.3-1% of all laryngotracheal stenosis.
As in this patient, congenital cardiac disease often accompanies CTS. Up to 50% of patients have some associated cardiovascular anomaly, most commonly a left pulmonary artery sling, but may also have a patent ductus arteriosus, double aortic arch, atrial or ventricular septal defects, or an aberrant subclavian artery. Extracardiac anomalies can also be present, involving the pulmonary (pulmonary agenesis or hypoplasia, tracheal bronchus), renal, gastrointestinal, or skeletal systems. Mortality in these patients, then, is related not only to the severity of stenosis, but also to the presence of comorbid anomalies.
Diagnosis can be difficult as these associated cardiac anomalies can mimic the respiratory symptoms of CTS. Often times, diagnosis is not made until the patient presents with a respiratory tract infection that induces further luminal narrowing, or until an unrelated elective procedure where difficult intubation is encountered.
This variability in the timing of diagnosis reflects the variability of stenosis that can occur. Patients may have generalized hypoplasia of the trachea, a funnel type stenosis, or segmental stenosis involving 2-3 rings. This anatomic description also correlates with symptoms, with those having generalized hypoplasia presenting earlier in life with stridor, wheezing, and respiratory distress, whereas those having segmental stenosis may be symptomatic only later in life or asymptomatic altogether.
Fig 1: Anatomic classification from Cantrell and Gould. Type I is generalized hypoplasia, Type II is funnel type stenosis with one normal end and the other one stenotic, and Type III is segmental stenosis with two or three cartilage rings involved
Patients are thought to become symptomatic when greater than 50% stenosis occurs, and dyspneic at rest with 75% stenosis. Given that the average diameter of a full-term neonate is 6 mm, symptoms would thus be expected at a stenosis of 3 mm. That this patient had approximately 50% stenosis but no accompanying signs of stridor, wheezing, or retractions only underscores the diagnostic dilemma in patients with concurrent pulmonary overcirculation due to congenital cardiac disease.
Management of CTS has entailed conservative as well as surgical approaches depending on the presentation and severity of the stenosis. There is a subgroup of patients who develop symptoms later in their first year of life who simply outgrow their stenosis and who can be followed without intervention. Those who need surgery tend to be symptomatic early on in life. The options in these patients include resection of the affected segment and reanastomosis of the trachea in short segment stenosis, and tracheal grafting or slide tracheoplasty in patients with long segment stenosis.
Because a slide tracheoplasty uses only native tracheal tissue and provides an increased airway diameter without the need for extensive mobilization or tension on suture lines, this has become the preferred technique for repairing long segment stenosis. The procedure is demonstrated below. Risks that one should be aware of are those associated with the extensive dissection, namely injury to the recurrent laryngeal nerve, esophagus, pulmonary vessels, and tracheal vascular pedicles.
Postoperative care is usually guided by a period of intubation to stent the trachea, and a combination of intravenous steroids in the immediate postoperative period and inhaled steroids over several weeks postoperatively to decrease edema and the risk of restenosis from granulation tissue.
References
- Herrera P, Caldarone C, Forte V, et al. The current state of congenital tracheal stenosis. Pediatr Surg Int 2007; 23:1033-1044.
- Ho, AS, Koltai PJ. Pediatric tracheal stenosis. Otolaryngol Clin N Am 2008; 41: 999-1021.
- Terada M, Hotoda K, Toma M, et al. Surgical management of congenital tracheal stenosis. Gen Thorac Cardiovasc Surg 2009; 57:175-183.
- Lipshutz GS, Jennings RW, Lopoo JB, et al. Slide tracheoplasty for congenital tracheal stenosis: A case report. Journal of Pediatric Surgery 2000; 35(2):259-261.
