Massive airway myiasis: an extreme rarity

Abstract

Intubations are important live saving skills to maintain adequate ventilation and oxygenation. Common indications include impending upper airway obstruction, respiratory failure and impaired conscious level. Oral myiasis is an infrequently found disease which is characterised by ectoparasitic infestation of body tissues by fly maggots.

We present a case report and share valuable experiences on a patient with massive airway myiasis causing upper airway obstruction which require emergency intubation.

Background

Myiasis is a parasitic disease which involves the invasion of fly maggots onto human or animal tissues.¹ Oral myiasis is extremely uncommon as compared with cutaneous myiasis.² It is often associated with individuals who are immunocompromised, requiring special needs and poor oral hygiene.³ Urgent airway management is needed to prevent total upper airway obstruction due to migration of maggots and laryngeal oedema.

We present an extremely rare case of a middle age man with massive airway myiasis causing upper airway obstruction.

Case presentation

A middle-aged heathy man presented to us with a history of progressive painless nasal swelling for a duration of 2 months which was associated with massive growth of wriggling maggots in his nose and mouth for the two past days prior to admission. He denied any loss of weight and appetite. There was no history of facial trauma, per oral bleeding nor family history of malignancies. He was thinly built and appeared cachectic with a weight and height of 50 kg and 175 cm, respectively. His respiratory rate was 22 breaths/min and was seen breathing from the mouth. The oxygen saturation on room air was 95%. There were no audible rhonchi or stridor and he was able to lie flat on the bed. The blood pressure (BP) and heart rates were within normal ranges. A CT scan of the thorax was unable to be done due to severity of his condition and financial constraints. The initial provisional diagnosis was nasal myiasis due to an infected malignant airway tumour with impending upper airway obstruction.

He was urgently posted for an emergency wound exploration, debridement, biopsy and removal of maggots under general anaesthesia in the operating theatre by the otorhinolaryngology (ORL) team. The airway assessment showed features of very difficult airway such as grossly swollen nose, which was filled with crawling maggots, swollen lips, limited mouth opening due to perioral oedema and poor dentition. There were necrotic patches seen on the nasal cavity and lips. His neck extension was adequate, with thyromental distance more than 6 cm (figure 1).

Figure 1.

A preoperative frontal view of the patient showing nasal myiasis.

The immediate anaesthetic plan was for oral awake fiberoptic intubation (AFOI) using targeted controlled infusion (TCI) of remifentanil in order to maintain spontaneous ventilation and ORL team to standby for tracheostomy under local anaesthesia (LA) in case of failed AFOI or any sudden respiratory collapse. The BP cuff, ECG, end tidal carbon dioxide and pulse oximeter were placed on the patient. After that, the patient was given intravenous dexamethasone 0.25 mg/kg and glycopyrrolate 4 µg/kg prior to AFOI. TCI of remifentanil was commenced and maintained at a range of 2–9 ng/mL throughout AFOI.

A size 6.0 mm flexible fiberoptic scope was introduced slowly via the oral cavity. There was grossly distorted upper airway anatomy, massive necrosis of the oropharynx and many maggots burrowing. The epiglottis, arytenoid cartilages and vocal cords appeared inflamed and swollen with narrow opening.

To avoid further airway trauma such as bleeding and oedema together with frequent blurring of fiberoptic scope by maggots, both teams decided to abandon the procedure and proceeded for tracheostomy under LA. Intraoperatively, we applied 2 mg/kg of bupivacaine 0.5% with epinephrine (1:200 000) for subcutaneous infiltration and supplemented with TCI of remifentanil in the range of 3–6 ng/mL. A horizontal incision was made at the second tracheal ring. The patient’s vital signs were stable throughout the procedure without any major cardiorespiratory complications. A size 8.0 mm tracheostomy tube was successfully inserted by the surgeon without any difficulties. No signs of maggots’ infestation were seen in the lower airway below the carina as a flexible fiberscope was passed through the tracheostomy tube. Hundreds of maggots were successfully removed, dental clearance performed, necrotic tissues debrided and samples were sent for histopathological examination (HPE).

Outcome and follow-up

Postoperatively, the patient was sent to the ward with a tracheostomy mask 40% oxygen supplement and was stable (figure 2). He was started on intravenous cefuroxime and metronidazole to cover for sepsis for 5 days. The HPE results of the nasal mass showed extranodal nasal natural killer/T cell lymphoma, which is a rare and aggressive type of non-Hodgkin's lymphoma. He was planned for CT scan of brain, neck, thorax, abdomen and pelvis for staging of disease. He was also referred to the oncology team for initiation of chemotherapy.

Figure 2.

A photo showing an extensive wound debridement.

Discussion

Chrysomya bezzania, also known as Old World screwworm fly, is an obligate parasite that feeds on human and animal tissues to cause a rare disease called myiasis.⁴ The maggots burrow themselves on subdermal tissues of the oral cavity, orbits, urogenital or neglected wounds to cause necrosis and inflammatory reactions, leading to tissue oedema and sepsis.

Oral myiasis is very uncommon and had been reported in subtropical countries in patients with foul smelling wounds, prior dental surgeries and poor oral hygiene which attracts flies to lay eggs.³ The infiltrating maggots will not only cause static obstruction but also present a dynamic danger to the patient. An ascending oral myiasis can intrude the orbits, ear and brain whereas a descending myiasis can cause upper airway obstruction, aspiration pneumonia, upper gastrointenstinal bleeding and disseminated sepsis. This explained why our patient had distorted nasal and oral anatomy with early signs of an impending upper airway obstruction.

The gold standard in managing patients with anticipated difficult intubation is by AFOI.⁵ This was chosen in view of our patient having features of a difficult airway. As the patient had signs of impending airway obstruction, we decided to use TCI of remifentanil in optimum doses and ‘spray as you go’ method with lignocaine 0.5% in multiple aliquots of 2–3 mL, keeping in mind to always maintain spontaneous respirations.

There were many obstacles that we faced throughout to successfully perform the AFOI and tracheostomy. We were unable to clearly visualise the upper airway structures as the mouth opening was very limited due to pain and perioral swelling. Maggots were constantly seen crawling out from the mouth and nostrils, causing discomfort to the anaesthesiologist, assistants and patient to properly focus and perform AFOI in a calm manner. The maggots also obscured the fibrescope view causing the AFOI operator to stop several times to clean and carefully manoeuvre it to negotiate the grossly distorted upper airway structures which was necrosed and friable. Hundreds of maggots were removed manually during the procedure. However, due to lack of laboratory pathological testing at our centre, the species of those maggots was not able to be identified.

There were difficulties to predict the extent of maggots’ infestations as CT scan of the neck and thorax was not done prior due to the urgency of this case. This gave us many uncertainties of what potential airway issues that may arise intraoperatively.

Due to the complexity of this case, we had a backup plan of tracheostomy under LA by the ORL team. An experienced ORL surgeon and team were all scrubbed up and standby in anticipation of an emergency tracheostomy.

Learning points.

• Massive airway myiasis is always an acute emergency.

• The managing team must be psychologically strong when dealing with large amounts of minute maggots crawling from the distorted airway.

• A proper preparation in anticipation of a potentially difficult awake fiberoptic intubation, procedural failure and a good teamwork is essential to ensure patient safety.

• A CT scan of the neck and thorax may be helpful to delineate the extent of airway distortion prior to the procedure.