Iatrogenic surgical emphysema and pneumomediastinum in a case of emergency lower segment caesarean section.

INTRODUCTION

Incidence of difficult airway in the obstetric population is high (0.3%), but multiple reattempts should be avoided to prevent trauma and likely desaturation.[1] Proseal laryngeal mask airway (PLMA®)/LMA Supreme® (SLMA) can be the first choice after failed intubation attempts as these two devices have been shown to be effective. These devices have their own problems, however, and one such potential complication is presented in this case report.

CASE REPORT

A 22-year-old female of American Society of Anaesthesiologists physical status I was transferred to our hospital from a peripheral hospital following emergency lower segment caesarean section (LSCS) for non-progress of labour. After a failed initial spinal anaesthesia, general anaesthesia (GA) was planned with controlled ventilation after endotracheal intubation (ETI). The patient (body mass index-25) was nil per oral as per protocol, and Cormack-Lehane airway assessment grade was 4. Multiple attempts at intubation failed and finally a blind effort with stylet was successful. The patient developed respiratory distress when the trachea was extubated after surgery. Re-intubation was not possible, and airway was secured with PLMA size 3. Proper placement of PLMA was confirmed, but oxygen saturation levels on pulse oximetry (SpO2) did not improve (94–96% on 100% oxygen as reported by the anaesthesiologist in the peripheral hospital). Surgical emphysema was observed around the neck. Decision to transfer the patient to our hospital was made at this juncture.

On receiving in our Intensive Care Unit, the patient was sedated, paralysed and put on positive pressure ventilation (PPV) through a Bain's circuit. Extensive surgical emphysema was seen on the neck, upper chest and face. Pulse rate was 90/min, non-invasive blood pressure 100/70 mmHg, and SpO2 was 91–92% on 100% oxygen. Bilateral air entry was present though diminished at the right base. Superficial skin incisions were put over the chest and neck to reduce the surgical emphysema. Chest X-ray (CXR) showed minimal pneumothorax on the right side, pneumo-mediastinum bordering pericardium and right lower lobe opacities [Figure 1]. A chest tube was inserted on the right side. Arterial blood gas analysis (ABG) showed PaO2 of 68 mmHg, PaCO2 57 mmHg, SaO2 92%, pH 7.34, HCO3 -28 mmol/l. In view of the increasing surgical emphysema, we suspected some upper airway trauma and intubation of the trachea was done with a 6.5 mm internal diameter endotracheal tube (ETT) with the help of a tube exchanger using PLMA as a conduit. Ventilator was set on synchronised intermittent mandatory ventilation mode. SpO2 gradually improved to 98–99% (FiO2 0.5). Contrast-enhanced computed tomography scan of neck and thorax showed marked subcutaneous emphysema and air along all neck spaces and muscle planes, bilateral pneumothorax (right > left), pneumomediastinum and surrounding alveolar opacities. Mediastinal vasculature and oesophagus were normal. No obvious airway injury was visualised. Bilateral chest tubes were inserted after this. Fibreoptic bronchoscopy was performed to look for any trauma in the airway and revealed a traumatic rent in the right pyriform fossa along with mucosal injury just above the carina. Bilateral chest tubes were left in situ to function as conduits for the mediastinal air in case a pleural-mediastinal communication existed. CXR at 6 h showed a reduction in pneumothorax without any further increase of pneumo-mediastinum. The patient was now awake with stable haemodynamics and fully expanded lungs. Surgical emphysema had diminished, and ABG analysis showed a normal picture. Ventilatory support was weaned over the next 6 h to continuous positive airways pressure (5 cm H2O)-pressure-support ventilation (10 cm H2O) mode. Subsequent CXR at 12 h showed that pneumo-mediastinum was reduced in size. Finally, the patient was extubated with the difficult airway trolley ready for re-intubation. Post-extubation respiratory rate was 18/min with normal ABG.

Figure 1

Chest X-ray showing pneumomediastinum and pneumothorax

DISCUSSION

Both traumatic and spontaneous pneumothorax and subcutaneous emphysema have been reported following LSCS under GA. Aye et al.[2] reported bilateral spontaneous pneumothorax and subcutaneous emphysema on emergence. Traumatic subcutaneous emphysema with pneumothorax and pneumomediastinum due to the development of tracheoesophageal fistula has also been reported after LSCS under GA.[3] Incremental risk must be assumed with each failed intubation attempt, and more than three attempts require compelling justification.[4] PLMA or SLMA could have been the first choice for securing the airway in this case after two failed intubation attempts. Efficacious use of PLMA and SLMA has been shown in obstetric cases with no evidence of aspiration.[5678] SLMA has been advocated to be an alternative to ETT in a carefully selected patient population of slim fasting parturients undergoing elective or semi-urgent LSCS by Yao et al.[7] Practice guidelines for management of the difficult airway (2013) have incorporated the LMA both for ventilation and as a conduit for intubation while the update of Difficult Airway Society guidelines (April 2015) recommends the use of second generation supraglottic airway devices (SGD) like PLMA and SLMA.[910] Endotracheal intubation (ETI) through intubating LMA would also be a good alternative to avoid trauma with the use of stylet as suspected in this case. SGD cannot be recommended for all elective caesarean sections at this time. Nevertheless, many studies support early use of SGD for airway rescue in parturients (level of evidence B).[4]

Some of the problems with the use of SGD are gastric insufflation, airway obstruction and trauma, which can occur even on correct placement.[11] In the case of upper airway trauma with subsequent surgical emphysema, PPV with PLMA could be detrimental. As evident in our case, injury to the pyriform fossa led to massive surgical emphysema during transfer to our hospital with PPV. As soon as the surgical emphysema was detected, PLMA was replaced with an ETT with a favourable outcome. Placement of an ETT would also seal any rent in the trachea above the carina to prevent further increase in resultant pneumo-mediastinum or pneumothorax whereas ventilation through an SGD would, in fact, aggravate such complications.

CONCLUSION

The availability of useful SGDs should enable us to avoid iatrogenic airway trauma with repeated intubation attempts in the fragile obstetric airway. Even though the PLMA and SLMA have been shown to be effective devices in difficult airway situations, it is important to bear in mind that individual cases might warrant the insertion of an endotracheal tube instead of SGDs so as to avoid potential complications.

Financial support and sponsorship

Deen Dayal Upadhyay Hospital.

Conflicts of interest

There are no conflicts of interest.