Takashi Asai

Effect of cricoid pressure on placement of the I‐gel™: a randomised study

We studied 40 adult patients to see if cricoid pressure affected placement of the I‐gel™. In a randomised crossover design, the i‐gel was placed with and without cricoid pressure, and we compared the success rate of adequate ventilation through the i‐gel, time to placement and the rate of optimal position of the device between the two circumstances. Cricoid pressure significantly decreased the success rate of adequate ventilation through the i‐gel (40 vs 34 patients) (p = 0.041, 95% CI for difference 4–26%), and significantly decreased the rate of the optimal position (39 vs 17 patients) (p < 0.001). The time to achieve adequate ventilation was significantly longer (p < 0.001) with cricoid pressure than without (median difference 8 s; 95% CI for median difference 3–12 s). Cricoid pressure significantly decreases the success rate of ventilation through the i‐gel, but the success rate of ventilation through the i‐gel is reasonably high.

Emergency Cricothyrotomy: Toward a Safer and More Reliable Rescue Method in “cannot Intubate, Cannot Oxygenate” Situation

Anesthesiology, V 123 • No 5 995 November 2015 I F oxygenation is difficult due to failed tracheal intubation and difficult ventilation via a facemask after induction of anesthesia, all the major guidelines on “difficult airway management” recommend to insert a supraglottic airway, and if that is ineffective, to gain invasive access to the infraglottic airway (such as cricothyrotomy and tracheostomy) as the last resort.1–3 Nevertheless, this invasive method as the last resort may also fail, rendering the current strategies for difficult airway management not ideal.4 In this issue of ANesthesIology, siddiqui et al.5 have shown that emergency percutaneous cricothyrotomy may frequently produce another lifethreatening complication (tear to the posterior tracheal wall) and that ultrasonography may drastically reduce this complication.

Rethinking general anesthesia for cesarean section.

In this review, we describe the current consensus surrounding general anesthetic management for cesarean section. For induction of anesthesia, rapid-sequence induction using thiopental and suxamethonium has been the recommended standard for a long time. In recent years, induction of anesthesia using propofol, rocuronium, and remifentanil have been gaining popularity. To prevent aspiration pneumonia, a prolonged preoperative fasting and an application of cricoid pressure during induction of anesthesia have been recommended, but these practices may require revision. Guidelines for difficult airway management were developed first in obstetric anesthesia, and the use of a supraglottic airway is now recognized as an effective rescue device. After the delivery of a fetus, switching from volatile anesthetics to intravenous anesthetics has been recommended to avoid uterine atony. At the same time, intraoperative awareness should be avoided. The rate of persistent wound pain is higher when only general anesthesia was used during cesarean section than with regional anesthesia, and thus it is necessary to provide a sufficient postoperative analgesia using multimodal analgesia, including intravenous patient-controlled analgesia (IV-PCA), transversus abdominis plane (TAP) block, non-steroidal inflammatory drugs, and acetaminophen.

Monitoring during difficult airway management

Monitoring is crucial to assure safety during difficult airway management. Several reports have indicated that the most of the adverse outcomes associated with difficult airway management could have been avoided with the use of necessary monitors, such as a pulse oximeter and a capnometer. Nevertheless, airway complications continue to be major problems during anesthesia, in particular, in patients with difficult airways. In this brief review, I stress the role of monitoring in detecting inadvertent esophageal intubation, during sedation for awake tracheal intubation, during general anesthesia, and during emergence from anesthesia, in patients with difficult airways.

Airway management in patients undergoing emergency Cesarean section

Special care is required for airway management of patients undergoing emergency Cesarean section. Although the incidence of difficult intubation and difficult ventilation is similar between pregnant and non-pregnant women, the severity of complications in pregnant patients would be much greater than in non-pregnant patients, if tracheal intubation is found to be difficult: increased risk of pulmonary aspiration, hypoxia, airway obstruction due to laryngeal edema, and a “sleeping baby” being taken out. Rapid-sequence induction of anesthesia is generally indicated to a patient undergoing emergency Cesarean section under general anesthesia. The technique has been evolving, without losing the key premise of minimizing the period of the airway being not protected from pulmonary aspiration, and of permitting rapid wake up if tracheal intubation fails. In this review, I describe the appropriate airway management, based on the current state of knowledge, in a patient undergoing emergency Cesarean section under general anesthesia.

Cannot intubate cannot ventilate—focus on the 'ventilate'

In this issue, Tachibana and colleagues [1] have reported much dreaded ‘‘cannot intubate, cannot ventilate’’ during anesthesia. Their results suggest that this is uncommon (1 in 32,000 cases), but with potentially catastrophic outcomes. In the 1990s [2], the incidence of death or permanent brain damage associated with airway management during general anesthesia was found to be much higher than the incidence associated with cardiovascular management, and since then several major efforts have been made to reduce the serious adverse outcomes associated with airway management. These include guidelines for difficult airway management formulated by major anesthesiology organizations [3–5], development and use of new and reliable airway devices, and widespread monitoring with oximetry and capnography [6]. Nevertheless, a recent nationwide prospective survey (the 4th National Audit Project, NAP4) has shown that serious airway complications still occur for a small number of patients, with an estimated incidence of 1 per 5,000–22,000 patients in the UK [7]. The report of Tachibana and colleagues [1] indicates that Japan and, very likely, other nations face similar challenges. So what is new about the report of Tachibana and colleagues [1]? All the hospitals in Tachibana’s report were equipped with a videolaryngoscope (Pentax Airway Scope), which has advantages over conventional laryngoscopes. Tachibana’s report [1] indicates that the availability of videolaryngoscopes did not seem to reduce the incidence of ‘‘cannot intubate, cannot ventilate’’ situations if several attempts at tracheal intubation had been made with a conventional laryngoscope.

Residual neuromuscular blockade after anesthesia: a possible cause of postoperative aspiration-induced pneumonia.

260 February 2014 P aspiration is rare during daily life, thanks to amazingly well-organized protective mechanisms, such as swallowing (and coordinated cessation of breathing during swallowing), coughing, and laryngeal closure.1 If any part of these mechanisms is impaired, the risk of aspiration increases. In this issue of ANesthesIOLOgY, hårdemark Cedborg et al.2 have shown that in asymptomatic elderly people, pharyngeal function is often impaired, and that residual effect of a neuromuscular-blocking agent after general anesthesia would worsen the impairment. The research group extended their previous works performed in healthy young volunteers3–5 and provides physiological evidence for partial paralysis as a possible cause to postoperative aspiration-induced pneumonia in elderly people.

Are video laryngoscopes useful for paramedics during cardiopulmonary resuscitation

Ota et al. [3] performed an observational study comparing the success rate of tracheal intubation using a video laryngoscope (Pentax Airway Scope) by paramedics with and without previous training of tracheal intubation using a Macintosh laryngoscope in anesthetized patients. The success rate of tracheal intubation using the Airway Scope was high for both groups of paramedics, indicating the usefulness of the video laryngoscope. In addition, to somewhat a surprise, the success rate of tracheal intubation at the first attempt with the video laryngoscope was significantly higher (96 %) for paramedics without previous training with a Macintosh laryngoscope than for those with previous training with a Macintosh laryngoscope (64 %).

Progress in difficult airway management

Because of this, some authors consider that predictive tests are futile; however, prediction tests should be performed, as they frequently do identify difficult airways, and would reduce the incidence of serious airway complications after induction of anesthesia [13]. Sufficient pre-oxygenation of the patient is crucial, particularly when difficult airway management is predicted. The traditional method is to provide oxygen via a facemask for a minimum of three minutes. Recently, a highflow nasal oxygen delivery system has been shown to be effective in reducing the risk of hypoxia during attempts at awake fiberoptic intubation [15]. Some authors consider that a neuromuscular blocking agent should not be given after induction of anesthesia until adequate ventilation via a facemask has been confirmed, but there is considerable evidence to support this practice being unsuitable. It is now clear that injection of a neuromuscular blocking agent immediately after induction of anesthesia facilitates mask ventilation and reduces the incidence of hypoxia [16]. During laryngoscopy, oxygen may be insufflated to the posterior pharynx to delay the time to become hypoxic [17].

Are videolaryngoscopes useful for nasotracheal intubation

Nasotracheal intubation has been used as an established method of airway management since 1902, when Kuhn [1] was the first to report this method. Nevertheless, compared with orotracheal intubation, fewer studies have been done on nasotracheal intubation to increase the success rate of intubation and to reduce complications. In this issue of the Journal of Anesthesia, Ono and colleagues [2] report the efficacy of a videolaryngoscope (Pentax Airway Scope) for nasotracheal intubation, factors that may make nasotracheal intubation more difficult, and solutions to these difficulties.