Microcuff® Tubes in Neonates: Do we know the Safe cuff Pressures?

Sir, The Microcuff® (AVANO, Roswell, GA) tubes are specially designed tubes for pediatric use, having a short, distally placed cuff made of micro-thin soft polyurethane allowing the cuff to inflate below the cricoid at a lower inflation pressure to seal the trachea.[1] With the introduction of the Microcuff® pediatric endotracheal tube (ETT) in 2004, more pediatric anesthesiologists are incorporating cuffed tubes into their practice.[2] Nevertheless, the literature concerning the safety and superiority of using Microcuff® tubes in the neonatal age group remains limited.[3] A day 3, full term, 2.8 kg neonate with moderate pulmonary hypertension was posted for thoracoscopic left congenital diaphragmatic hernia repair. The baby was mechanically ventilated through 3.5-mm uncuffed ETT in the neonatal intensive care unit (NICU). In the operating room, after anesthesia induction, a significant leak of about 10 to 15 ml (>50%) was detected around the 3.5-mm ETT at a pressure of l0 cm H2O, which was not compensated by the ventilator (Drager Perseus A500). Although the manufacturer does not recommend using the 3.0-mm Microcuff® tube in <3 kg, as the procedure was planned thoracoscopically, we chose to insert a 3.0-mm Microcuff® tube instead of placing a throat pack. The intubation was performed using a C-MAC videolaryngoscope (Karl Storz, Tuttlingen, Germany) in a single attempt, and cuff pressure was kept at around l2 cm H2O with a minimal leak of 3–4 ml as evidenced by the flow volume loop. Cuff pressure was monitored post-intubation and after right lateral positioning and limited to <12 cm H2O using a cuff pressure manometer (Posey Portex Arcadia, CA 91006, USA). After 3 hours of surgery, the patient was planned to be ventilated in the NICU. Since the neonatologist was unfamiliar with Microcuff tubes and their ventilator adequately compensated for peritubal leak, an exchange for an uncuffed ETT was planned. Under C-MAC guidance, an initial 3.5-mm uncuffed ETT could not be negotiated beyond the vocal cords raising the suspicion of subglottic edema. A 3.0-mm snugly fitting uncuffed tube was then inserted, which showed no peritubal leak. Considering subglottic edema, intravenous dexamethasone 0.2 mg/kg 8 hourly was given postoperatively. On postoperative day 2, a peritubal leak around the 3.0-mm microcuffed ETT was revealed and the tube was changed to a 3.5-mm uncuffed ETT, which needed a further upgrade on postoperative day 5 to a 4-mm ETT. Most likely, our patient had subglottic edema, which settled with time as evidenced by the need to change the tube twice in the postoperative period. We can attribute this mostly to the use of the Microcuff tube. Despite several precautions, this case displays the need to urge caution when using cuffed tubes in neonates. With the lack of high-quality evidence and large randomized controlled trials in this vulnerable population, the use of cuffed tubes must be decided on a case-to-case basis after analyzing the risk/benefit of the same.[4] In addition, the safe limits of cuff pressure are undetermined and one should opt for lower inflation pressures if using cuffed tubes in neonates. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.