Literature Review for Office-Based Anesthesia

Itagaki T, Oto J, Burns SM, Jiang Y, Kacmarek RM, Mountjoy JR. The effect of head rotation on efficiency of face mask ventilation in anaesthetized apnoeic adults. Eur J Anaesthesiol . 2017;34:432–440.

Head rotation is known to increase the cross-sectional area of the upper airway in normal, awake subjects and during drug-induced sleep endoscopy. Head rotation also improves upper airway patency in patients with upper airway obstruction with obstructive sleep apnea. In this randomized crossover study, the authors hypothesized that head rotation would reduce upper airway obstruction and improve tidal volume during mask ventilation of apneic, paralyzed patients. Forty patients, aged 18–75 years and with a body mass index between 18.5 and 35, requiring general anesthesia for elective surgery were studied. Expiratory tidal volume, measured with a respiratory inductive plethysmograph, was recorded immediately after anesthetic induction with the head in both the neutral position and a 45° rightward rotation. All patients benefited from the 45° head rotation, as reflected in significantly improved tidal volumes. The authors concluded that head rotation in the anesthetized, apneic adult increased the efficiency of mask ventilation and is a useful technique for improving mask ventilation when obstruction is encountered.

Comment: Although previous publications have shown that difficult mask ventilation often coexists with difficult tracheal intubation, the authors point out that providing optimal mask ventilation has not been appreciated to the same extent as successful tracheal intubation. Drawing upon physiological evidence, clinical observation, and previously published clinical studies, this carefully controlled study provides strong evidence for using head rotation as a means of optimizing the efficiency of mask ventilation during anesthetic induction. The study was limited to anesthetized, paralyzed adults and cannot be extrapolated to children without further study. (Summary MA Saxen)

Muffly MK, Chen ML, Claure RE, Drover DR, Efron B, Fitch WL, Hammer GB. Small-volume injections: evaluation of volume administration deviation from intended injection volumes. Anesth Analg. 2017;125:1192–1199.

This ex vivo study examined the degree to which administered injection volumes differed from intended volumes below 0.5 mL. Ten attending pediatric anesthesiologists and 10 pediatric postanesthesia care unit (PACU) nurses used separate 1-mL tuberculin syringes and 18-gauge needles to administer 5 volumes (ranging from 0.025 to 0.5 mL) of yellow fluorescent dye through an intravenous (IV) stopcock into IV tubing with free-flowing normal saline. Microplate fluorescence wavelength detection was used to measure the fluorescence of the injected and collected fluid. A volume deviation of 10% or greater between intended and delivered doses was considered clinically significant, following the US Pharmacopeia standard that the concentration of IV infusions must not vary by more than 10%. As expected, the amount of variation between intended and delivered doses increased as the intended volume decreased. Substantial underdosing and overdosing were noted in all volumes. There was no significant difference in the discrepancies of pediatric anesthesiologists and PACU nurses. These findings confirm a greater risk of clinically significant injection errors with the injection of small, concentrated volumes.

Comment: The use of small, concentrated drug preparations is appealing to the mobile office-based anesthesiologist who provides all needed drugs and anesthesia armamentarium in each location. However, this study demonstrated that as much as a threefold overdose of some commonly used anesthetic drugs can occur when injecting with a tuberculin syringe and 18-gauge needle, even when injection is performed by experienced practitioners. Errors have the potential for compounding when several intravenous drugs are used, and the risk of dosing errors is magnified when treating a pediatric population. The authors recommend the use of less-concentrated preparations when possible, to prevent unintended drug dosing errors. (Summary MA Saxen)

Chang JE, Kim H, Han SH, Lee JM, Sangwan JI, Hwang J-Y. Effect of endotracheal tube cuff shape on postoperative sore throat after endotracheal intubation Anesth Analg. 2017;125:1240–1245.

Postoperative throat occurs with a reported incidence of 21–74% in patients who have undergone endotracheal intubation. This controlled, randomized study of 91 adult patients compared the incidence of incidence of sore throat following intubation with a conventional cylindrical cuff versus intubation with a tapered-shape cuff. Sore throat and hoarseness were assessed at 1, 6, and 24 hours postoperatively using a visual analog scale to express throat severity. Both sore throat and hoarseness were found to be less common with tapered cuffs at all time points, with a significant difference (p < .05) for sore throat at 6 hours. The authors attribute the results to the smaller cuff-trachea contact area associated with tapered-cuff endotracheal tubes.

Comment: This study was performed in patients undergoing general, orthopedic, urologic, and gynecologic surgery, with no mention of dental or oral surgery. Although this well-designed study contains data on number of intubation attempts, time to achieve intubation, and Cormack and Lehane grade, no mention was made of the average duration of surgery. Because the likelihood of sore throat is directly related to the time of intubation, details on the type and duration of the surgery would have further enhanced this paper for dentist anesthesiologists. (Summary MA Saxen)

Burjek NE, Nishisaki A, Fladjoe JE, Adams D, Peoples KN, Raman VT, Olomu PN, Kovatasis PG, Jagannathan N. Videolaryngoscopy versus fiber-optic intubation through a supraglottic airway in children with a difficult airway. Anesthesiology. 2017;127:432–440.

Identifying intubation techniques with a high first-pass success rate is a critical step in improving outcomes for children with difficult airways. Various intubation techniques and devices are currently available; however, their clinical usefulness has not been well studied. This observational, nonrandomized report examined 1603 difficult-airway cases collected from the Pedi-Registry, an outcome database sponsored by the Society for Pediatric Anesthesia. All children under 18 years were eligible if they were assessed to have a Cormack and Lehane classification greater than 3, displayed severely limited mouth opening or other anatomical abnormalities to restrict conventional laryngoscopy, had failed direct laryngoscopy within the past 6 months, or were deferred from direct laryngoscopy by the attending anesthesiologist following physical airway examination. Fiber-optic intubation through a supraglottic airway (FOI-SGA) was compared to videolaryngoscopy, with first-attempt success being the primary outcome. Both techniques were found to have similar rates of first-attempt success; however, selecting FOI-SGA as the first technique was associated with fewer intubation attempts and a significantly higher overall success rate. Hypoxemia was less common during FOI-SGA when continuous ventilation was used throughout the intubation attempt.

Comment: Fiber-optic intubation through a supraglottic device and videolaryngoscopy are relatively new airway management techniques. Office-based anesthesia providers may be contemplating whether either of these techniques has a place in their practice. This observational report of airway management in the most challenging of populations will help readers better understand the uses, limitations, and appropriate practice of these techniques. (Summary MA Saxen)

Logaugh LMY, Martin LD, Schleelein LE, Tyler DC, Litman RS. Medication errors in pediatric anesthesia: a report from the Wake Up Safe Quality Improvement Initiative. Anesth Analg. 2017;125:936–942.

The Wake Up Safe Initiative is the quality improvement database of the Society for Pediatric Anesthesia. Drawing from 2,316,635 anesthetics performed in 32 US institutions between 2010 and 2016, this study identified 276 medication-related errors. Opioids and sedative-hypnotics were most frequently associated with medication errors. These events comprised the third most common category of adverse events, second only to cardiac- and respiratory-related events. The most common type of error was accidental administration of the wrong dose, followed by accidental administration of the wrong syringe, ie, syringe swap. Over 80% of errors reached the patient, with over half causing patient harm. Approximately 5% required a life-sustaining intervention. Over 97% of the cases were determined to be preventable. The authors recommend the use of prefilled syringes, bar coding of medication at the point of administration, and 2-person checking of drug infusions as strategies for improving safety.

Comment: It is difficult to compare these important and interesting data to the outcomes of anesthesia providers performing office-based anesthesia for dentistry. No equivalent outcomes database currently exists in dentistry. Additionally, dental anesthesia represents a much narrower service regarding type of surgery, spectrum of medications, physical status and age of patients, and the number of people directly involved in drug delivery to patients (handoffs). In a 2015 presentation to the Society for Ambulatory Anesthesia (“Is Dental Office-Based Anesthesia More Problematic Than Other Types?” [Point-Counterpoint]. Presented at: 4th Annual Office-Based Anesthesia Seminar, Society for Ambulatory Anesthesia; October 23, 2015; San Diego, Calif), Urman cited data from the American Society of Anesthesiologists Anesthesia Closed Claims database relating to dental office–based anesthesia. Of 10,546 total claims collected between 1970 and 2013, 98 were dental office anesthetics. Respiratory events accounted for approximately 40% of claims and cardiovascular events approximately 13%, whereas medication-related errors represented less than 10% of claims. Still, this report should be of high interest to all anesthesia providers, because, as the authors note, anesthesiologists are uniquely predisposed to medication errors given the need to perform multistep drug preparations, personally calculate dosages, and administer drugs in relative isolation to the patient. (Summary MA Saxen)

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