Introduction
Idiopathic subglottic stenosis is a rare disorder, principally affecting females aged 20–40 years. It is characterised by progressive fibrosis with annular stenosis of the subglottic larynx (Figure 1). Various theories have been proposed as to the pathogenesis of the disorder.Reference Damrose1–Reference Valdez and Shapshay4 Symptoms usually include progressive dyspnoea, hoarseness and cough. The disorder is frequently mistaken for asthma, and diagnostic delay is common. Diagnosis is made by endoscopic evaluation and identification of the stenosis. Biopsy typically reveals fibrosis and/or chronic inflammation.
Fig. 1. Myer–Cotton grade 3 subglottic stenosis.
Treatment options for idiopathic subglottic stenosis include periodic dilation, cricotracheal resection and tracheostomy. A variety of endoscopic techniques have been described, including: dilation (rigid or balloon), with or without radial incisions; cryotherapy; mitomycin C application; and local steroid application.Reference George, Lang, Pasche and Monnier5–Reference Smith and Elstad10 Because of the recurrent nature of the disease, periodic retreatment is common.
There is no clear consensus on the optimal management of the disorder. Because idiopathic subglottic stenosis predominately affects females, often of child-bearing age, management of the disorder in pregnancy may be necessary. However, no clear treatment paradigm for these patients currently exists. Patients may become progressively symptomatic during the course of pregnancy, whether from progression of idiopathic subglottic stenosis, increased weight gain or both.
This study aimed to describe the use of balloon dilation, coupled with jet ventilation or high-flow nasal oxygenation, in the treatment of pregnant patients with idiopathic subglottic stenosis. We present four cases of idiopathic subglottic stenosis during pregnancy. In addition, we review the current literature, and provide recommendations for the evaluation, treatment and follow up of pregnant patients with idiopathic subglottic stenosis.
Materials and methods
Study design
This study was approved by the Institutional Review Board of the Stanford University Medical Center. The computer database of Stanford Hospital and Clinics, between 1 October 2003 and 30 September 2017, was used to identify those pregnant patients with subglottic stenosis who underwent airway dilation by the senior author. Four patients were identified, all of whom were treated in the manner described below.
Surgical technique
All of the airway dilations were performed in a standardised manner, with the patients under general anaesthesia. Patients were placed in a semi-recumbent position, and fetal heart rate monitoring was instituted as indicated. For each procedure, intravenous sedation with midazolam and fentanyl or remifentanil was used. Anaesthesia induction and maintenance were achieved with propofol. Rocuronium or succinylcholine allowed for paralysis to facilitate mask ventilation.
After the induction of anaesthesia, an adult Dedo-Pilling laser laryngoscope (Teleflex, Morrisville, North Carolina, USA) was introduced transorally, and suspended from a Mayo stand to visualize the glottis (Figure 2). Supraglottic jet ventilation was initiated in three cases; in one case, ventilation was performed using transnasal humidified rapid-insufflation ventilatory exchange (Optiflow™, Fisher and Paykel, Irvine, California, USA). A 0-degree 4 mm endoscope was advanced through the laryngoscope to visualise and grade stenosis severity using the Myer–Cotton grading scale (1–4).
Fig. 2. Dedo-Pilling laryngoscope with jet ventilation side port.
Dilation was performed with a 16 mm airway balloon (Inspira Air; Acclarent, Irvine, California, USA) (Figure 3). The balloon was inflated to 4 atmospheres of pressure for 30 seconds. Repeat dilation was performed if needed depending on the stenosis response.
Fig. 3. Acclarent continuous radial expansion balloon (a) and injector (b).
One percent lidocaine with 1:100 000 adrenaline-soaked pledgets were placed into the trachea and glottic area for haemostasis. In order to reduce fibrosis, triamcinolone-soaked (40 mg/ml) pledgets were applied for 1 minute at the level of the stenosis following dilation.
Mask ventilation was utilised if needed to assist emergence from anaesthesia. Fetal heart tones were reassessed in the post-anaesthesia care unit. Patients were discharged home the same day following obstetrical reassessment.
Results
Four patients required dilation during the course of their pregnancies. In three cases, the patient had a history of prior dilation for known subglottic stenosis, and in one case, the diagnosis was made during the course of pregnancy. Outcomes are shown in Table 1.
Table 1. Patient pre-operative and treatment characteristics
All patients had regular obstetrical and pre-natal care. An obstetrical consult was obtained prior to surgery for clearance of the patients. External fetal heart rate monitoring was performed for confirmation of fetal wellbeing before and after surgery in two of the cases, and continuous fetal heart monitoring was performed in the other two cases. No patient required further dilation through the completion of pregnancy. All four patients delivered full-term and fully viable infants via normal spontaneous vaginal delivery at a later date.
Discussion
Subglottic stenosis commonly arises secondary to endotracheal intubation, external trauma, or granulomatosis with polyangiitis (Wegener's granulomatosis).Reference Damrose1–Reference George, Lang, Pasche and Monnier5 It may also be idiopathic, as was the case in the series of patients presented here. Treatment options generally include dilation, cricotracheal resection and tracheostomy. Patients with idiopathic subglottic stenosis tend to be females of reproductive age.Reference Valdez and Shapshay4, Reference George, Lang, Pasche and Monnier5
Given the epidemiology of the disease, subglottic stenosis may present a therapeutic challenge in patients who become pregnant. It is well understood that maternal distress may have potentially devastating effects on the course of the pregnancy.Reference Mazze and Kallén11, Reference Scholz, Srinivas, Stacey and Clyburn12 Treatments likely to induce premature labour, or cause contractions, maternal hypoxia or acidosis, must be avoided.Reference Kuczkowski13 In order to minimise the risk of these complications, it is important to select a treatment method that is efficacious in maintaining the airway and oxygenation, and yet is minimally invasive, simple, expeditious, and minimises maternal and fetal stress.
Management of subglottic stenosis in pregnancy has only rarely been reported in the literature, and is limited to a small number of case reports (Table 2).Reference Scholz, Srinivas, Stacey and Clyburn12–Reference Carness and Berman26 Management options have included no intervention, intubation, dilation under inhalational anaesthesia, dilation using topical anaesthesia with or without intravenous sedation, and tracheostomy. In one case, the patient expired several weeks after delivery from subsequent airway obstruction.Reference Sutcliffe, Remington, Ramsay and Mason14 The literature offers, therefore, no clear consensus on the optimal management, both surgical and anaesthesia, in this group of patients.
Table 2. Patient characteristics and outcomes of previous reports
NSVD = normal spontaneous vaginal delivery; NA = not available; Nd:YAG = neodymium-doped yttrium aluminium garnet; IV = intravenous; KTP = potassium titanyl phosphate
Pregnancy incurs significant physiological and metabolic demands on the maternal body. The mother's respiratory system is already altered by pregnancy itself,Reference Cunningham27 and the added complication of idiopathic subglottic stenosis and potential for hypoxemia can be harmful to both the mother and fetus. If inadequately treated, idiopathic subglottic stenosis in non-pregnant patients can progress, and could result in pulmonary hypertension, oedema and respiratory failure.Reference Roediger, Orloff and Courey9, Reference Modgil, Havas and Mellis28 In pregnancy, inadequate oxygenation may be causally associated with ischaemic placental complications, including abruption, pre-eclampsia and intrauterine growth restriction.Reference Ananth and Vintzileos29 Although these complications are rarely caused by idiopathic subglottic stenosis, pregnant patients who have pre-existing idiopathic subglottic stenosis, or who develop idiopathic subglottic stenosis during pregnancy, may require treatment in order to prevent their occurrence.
There remains no consensus regarding the optimal treatment for idiopathic subglottic stenosis in non-pregnant patients. Some practitioners employ purely endoscopic techniques, such as radial incisions, balloon dilation, cryotherapy, topical mitomycin C or a combination of these. However, long-term re-stenosis rates are between 40 and 95 per cent.Reference Lee, Ko, Song, Shim and Kim8–Reference Smith and Elstad10 On the other hand, open techniques such as tracheal resection with re-anastomosis appear to offer higher success rates. Because these techniques are considerably more invasive, and constitute a much larger undertaking for the patient and physician, it is generally recommended that endoscopic therapy be pursued initially before attempting open procedures.Reference George, Lang, Pasche and Monnier5, Reference Giudice, Piazza, Foccoli, Toninelli, Cavaliere and Peretti6 Likewise, many different methods exist for achieving anaesthesia and ventilation during both the endoscopic and open surgical management of patients with subglottic stenosis.Reference Daumerie, Su and Ochroch30 Regardless of the method chosen, good communication between an experienced anaesthesiologist and surgeon is of paramount importance.
In the case of a pregnant patient with idiopathic subglottic stenosis, the risks of surgical intervention to both mother and fetus must be carefully considered. Surgery during pregnancy is associated with higher rates of premature delivery, intrauterine growth restriction and low birth weight.Reference Mazze and Kallén11 Although these complications of pregnancy are most commonly encountered in abdominal surgical procedures,Reference Kuczkowski13 surgery for idiopathic subglottic stenosis is still associated with a considerable risk of hypoxia and related injuries. For this reason, the American College of Obstetricians and Gynaecologists recommends involvement of the patient's obstetrician early in the planning process when considering surgical intervention in pregnancy.31
Other practitioners’ experiences of treating idiopathic subglottic stenosis in pregnancy emphasise the necessity of carefully choosing the best and least invasive procedure for these patients (Table 2). For example, in the case presented by Scholz et al., the authors noted an improvement in symptoms for the first 2 days post-operatively, with a subsequent deterioration in the patient's condition secondary to post-laser laryngeal oedema.Reference Scholz, Srinivas, Stacey and Clyburn12 Within a few days post-operatively, the patient developed pre-eclampsia with pulmonary oedema, which necessitated emergent upright caesarean section at 32 weeks of gestational age. Two other patients required tracheostomy for acute airway management: one in order to allow for the administration of labour anaesthesia, and the other for caesarean section.Reference Kuczkowski and Benumof32 The latter patient was initially intubated with a 4.0 microlaryngeal tube, but extubation subsequently failed in the intensive care unit and a tracheostomy was required.Reference Nanjegowda and Srinivasan23, Reference Karippacheril, Goneppanavar, Prabhu and Revappa24
Ratner et al. elected to use mask induction for the biopsy of a tracheal web, which proved to be an effective form of induction.Reference Ratner, Cohen, El Sayed and Druzin19 However, high ventilator pressures were required to maintain oxygenation. Salama and Body used a method of balloon dilation for acute airway management in their full-term patient to allow for normal delivery.Reference Salama and Body17 This is similar to the method of the current study, and was accomplished with minimal morbidity.
It is clear from these cases that there is both substantial variability in treatment strategies and potential risk related to airway management in the pregnant idiopathic subglottic stenosis patient. One investigator may have induced pre-eclampsia. Some patients were subjected to tracheostomy. Other patients required very high ventilation pressures in order to maintain oxygenation, which could have caused a pneumothorax. For this reason, airway management should be carefully considered and be clear to all providers involved in the care of these patients.
• Idiopathic subglottic stenosis is a rare but potentially serious condition, most common in younger females
• Idiopathic subglottic stenosis may occur, and/or require management, during pregnancy
• There is no consensus regarding optimal management of these patients or ventilation provision during airway surgery
• The technique of balloon dilation, with supraglottic jet or high-flow nasal cannula ventilation, is presented
• Compared to other methods, the technique is safe and effective
• All patients had lasting symptom resolution and normal spontaneous vaginal delivery at term
We have found total intravenous anaesthesia with paralysis, coupled with a non-invasive mode of oxygenation, to be a successful strategy in this patient population. Two previous studies by Salama and Body,Reference Salama and Body17 and Lee et al.,Reference Lee, Ko, Song, Shim and Kim8 have demonstrated the efficacy of endoscopic techniques and general anaesthesia, consistent with the findings of the current study. Optiflow has previously been demonstrated to be a safe method of ventilation in the operative management of airway stenosis, and was effective in one case in this study.Reference Tam, Jeffery and Sung33
Conclusion
When treating a patient with idiopathic subglottic stenosis, there are many options and variations. However, treatment options are more limited in the pregnant patient given the risks of surgery to mother and fetus. Previous studies have illustrated the necessity of being judicious in one's pursuit of therapy for idiopathic subglottic stenosis. It has been our experience with these four cases that balloon dilation, coupled with supraglottic jet ventilation or humidified high-flow oxygenation via nasal cannula ventilation, is safe, efficacious, and should be the primary mode of treatment for this patient population.
Competing interests
None declared
