Open orchidopexy surgery can be performed under spinal anesthesia or caudal block. Either of them has to be combined with general anesthesia because this child is 21-month-old. We are more familiar with caudal block which is almost conducted in all open orchidopexy surgeries in our hospital. Therefore we performed caudal block instead of spinal anesthesia. Due to the special facial appearance, hypotonia and tracheo/laryngomalacia caused by KdVS, children may have difficulty in ventilation and intubation. To prevent airway emergencies and preserve spontaneous breathing, we took some precautions. Firstly, we reduced the amount of long-acting opioid and slowed down the induction duration. The caudal block was performed to compensate for the insufficient analgesia caused by the reduction of long-acting opioid. Secondly, all the induction anesthetics were carefully chosen and administered cautiously. We chose etomidate instead of propofol because previous studies had shown less effect on respiration of etomidate compared to propofol [3]. Sevoflurane was selected and initiated from a low concentration of 1% increased by 0.5% every 10 to 20 breaths up to 3%. All the above measures were designed to test the effect of anesthetic drugs on the child’s airway potency after sedation. In the previous report about a KdVS patient who received an MRI exam under sedation, Ali mentioned the potential risk of increased sensitivity to nondepolarising neuromuscular blocking agents and the depressant effects of anesthetic agents related to hypotonia [2]. It had been proved that the child’s airway potency did progressively deteriorate as the sedation level elevated. If we didn’t keep the spontaneous breathing during anesthesia induction, a high risk of malignant hypoxic events might be developed by difficult ventilation. Extubation can be performed under deep sedation or awake. Since this child had tracheo/laryngomalacia and experienced difficult breathing during anesthesia induction, we thought it was beneficial to extubate awake. That was why we chose awake extubation. We removed the endotracheal tube when the child had body movements. Even if the above preparations and plans were made, oxygen desaturation still occurred when we removed the endotracheal tube during anesthesia recovery. This might be caused by the combined effects of tracheo/laryngomalacia, hypotonia related to KdVS as well as partial laryngeal spasm. Perhaps the child’s movement was not purposeful which meant he was not awake when we extubate him. We might have extubated him during light anesthesia. Etomidate instead of propofol or muscle relaxants was chosen to treat laryngeal spasm which did improve the airway obstruction and oxygenation in some extent. Lateral position further eased his breathing and re-intubation was avoided. He preferred prone position in PACU indicating deep extubation can be problematic. Perhaps extubation in deep anesthesia with lateral position may somehow prevent hypoxia.

Because of the less stimulation of the laryngeal mask which allowed reduction of anesthetics and free of muscle relaxant, and advantages for difficult airway management compared to endotracheal tube, we took it as the first choice for airway management. Previous studies had shown that inflatable and non-inflatable laryngeal masks could provide equal ventilation quality, and the i-gel presented a better sealing effect [4, 5]. Meanwhile, the gel-laryngeal mask is the most commonly used LMA in our center which usually provides very high seal pressure as good as inflatable LMAs. So we chose gel-laryngeal mask for this case. But it failed to provide adequate ventilation. The result confirmed that the endotracheal tube can also be inserted without muscle relaxant and provide better ventilation support. This suggested that an endotracheal tube may be more appropriate compared to a laryngeal mask for patients with hypotonia and tracheo/laryngomalacia. After extubated awake, he still had stridor and inhaled acetylcysteine (3 ml: 0.3 g) for 3 days to release the airway symptoms. This reminded us that prolonged postoperative monitoring and prevention of respiratory complications were necessary for these patients.

In addition, this patient also had hypothyroidism, indirect inguinal hernia, and syndactyly. Since KdVS is a relatively new discovered rare disease, it is unclear whether these co-existed diseases are related to KdVS. For our patient, these problems were controlled in the stable status which won’t significantly increase the perioperative risk. KdVS involves multiple systems and variable clinical features, such as growth retardation, seizures, structural central nerve system anomalies, neuropsychological disorders, scoliosis/kyphosis, hearing impairment, congenital heart anomalies, ectodermal abnormalities [1]. It is necessary to perform a comprehensive preoperative exam for these patients.

The specific facial dysmorphism, tracheo/laryngomalacia and hypotonia associated to KdVS makes airway management a challenge for anesthesia providers. Keep the spontaneous breath during induction period and carefully evaluate the effect of sedation to airway potency may be the key techniques. Endotracheal intubation is perhaps more suitable than laryngeal mask for such children, which can also be conduct with low-dose opioids and without muscle relaxants. Regional anesthesia can reduce the use of opioids. We should extubate awake, then a lateral or prone position may improve ventilation. The Koolen-de Vries syndrome involves multiple systems, thus individualized anesthesia protocol should be designed following a comprehensive evaluation.