We report an interesting case of intraoperative hiccups in an infant posted for double-J (DJ) stent removal under general anesthesia. We shall be highlighting the incidence, common reasons, and management described in the current literature.
A sudden inspiration followed by the abrupt closure of the glottis due to an involuntary myoclonic muscle contraction of the diaphragm and the intercostal muscles results in the generation of the hic sound during a hiccup. The hiccup reflex arc afferent limb consists of vagal, phrenic, and sympathetic chains from T6-12 that travel to the posterolateral part of the medulla oblongata, the hiccup center. The efferent pathway is through the motor fibers of the phrenic nerve and accessory nerves to the diaphragm and the intercostal muscles, respectively. A pressure gradient across the lower esophageal sphincter (LES) is created enabling gastroesophageal reflux and may increase the risk for pulmonary aspiration. The intraoperative hiccups must therefore need urgent management to prevent this complication. Also, the hiccups can be annoying and might interfere with the surgical or diagnostic procedure. Various causes have been postulated in the generation of intraoperative hiccups that include drugs like methohexital, thiopentone, midazolam, opioids, and dexamethasone, and recently, propofol has also been implicated. An inadvertent gastric insufflation during poor bag-mask ventilation technique or other patient-related factors, and prior diagnosis of gastroesophageal reflux disease may also present with intraoperative hiccups and are reported in about 4.5–9.5% of the patients. LMA insertion has been claimed to inhibit hiccups as well as implicated as a cause for this, with an overall incidence of 5% that differed with the type of induction agent used intraoperatively.
Our patient, a 3-month-old infant, weighing 3.5 kg, followed up case of Anderson–Hynes pyeloplasty for antenatally diagnosed pelviureteric junction obstruction. The patient had no other known comorbidities or congenital syndromes and was posted for DJ stent removal. Standard pre-anesthetic preparation for a pediatric patient as per institutional protocol was checked before taking the patient to the operating theater. No premedication was administered. Routine noninvasive monitoring of blood pressure, electrocardiogram, and pulse oximetry (SpO2) was started on arrival in the operation theater. General anesthesia was induced with a pediatric circle system prefilled with 8% sevoflurane in 60% nitrous oxide and 40% oxygen at a fresh gas flow of 6 L/min. Continuous measurements of carbon dioxide and sevoflurane end-tidal concentrations were made. Initially, the patients breathed spontaneously, and then ventilation was undertaken manually when the patient became apneic. An intravenous (IV) cannula was secured on the left-hand dorsum and injection of fentanyl 1 mcg/kg was administered. A laryngeal mask airway (Ambu® Aura40™ Reusable Laryngeal Mask, size #1.0) was inserted using a standard technique after confirming the loss of eyelash reflex and relaxation of the jaw. After the LMA placement, the child started having hiccups within one minute. The vitals were pulse 135/min, BP 75/50. Atropine 0.10 mg was given initially followed by an injection of atracurium 1.5 mg IV to control the hiccups but they did not stop. Continuous positive airway pressure (CPAP) of up to 20–25 cm of H2O was also maintained intermittently. None of the pharmacological or non-pharmacological maneuvers worked. Meanwhile, the procedure was initiated and continued by the expert surgeon. The procedure was completed successfully within just 15 min. There was mild abdominal distension but soft on palpation. Gastric insufflation was suspected to be one of the reasons, but nasogastric decompression of the stomach was not feasible due to the absence of a gastric channel in the device (Ambu® Aura40™). We decided not to intervene in-between as the procedure was about to finish. The patient was placed in a lateral position, neuromuscular blockade reversed with an appropriate dose of neostigmine and glycopyrrolate, and the LMA was removed in a deep plane while the breathing was spontaneous and of adequate tidal volume. An 8-French nasogastric tube (NGT) tube was inserted and about 80–100 ml of air was aspirated. The hiccups were settled immediately following air aspiration.
In our case, the cause of the intraoperative hiccups was gastric insufflation that might have occurred during assisted face-mask ventilation, as the patient had developed it soon after the induction of the anesthesia and placement of LMA. None of the drugs mentioned as a reason for the hiccups in the literature was used intraoperatively, except a small dose of fentanyl (4 mcg) LMA could have been a possible cause as the air kept filling the stomach as a one-way valve. However, even after the removal of LMA the hiccups did not stop, perhaps due to a patent GE junction valve. There are several pharmacological and non-pharmacological management strategies mentioned in the literature for the intraoperative hiccups with de-airing of the stomach as one of them.
In conclusion, we would like to mention that the intraoperative hiccups are very annoying both to the anesthetist and to the surgeon, and may also harm the patient by predisposing them to the risk of aspiration. LMA may occasionally be complicated with hiccups, especially in the absence of a nasogastric tube. Careful preventive strategies to avoid gastric insufflation, early detection of the cause, and appropriate management are very important in such cases to prevent any complications.
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