Andrew G. Roth

The Effects of Steep Trendelenburg Positioning on Intraocular Pressure During Robotic Radical Prostatectomy

BACKGROUND: Intraocular pressure (IOP) increases in steep Trendelenburg positioning, but the magnitude of the increase has not been quantified. In addition, the factors contributing to this increase have not been studied in robot-assisted prostatectomy cases. In this study, we sought to quantify the changes in IOP and examine perioperative factors responsible for these changes while patients are in the steep Trendelenburg position during robotic prostatectomy. METHODS: In this prospective study, we measured IOP using a Tono-pen® XL in 33 patients undergoing robot-assisted prostatectomy. The IOP was measured before anesthesia while supine and awake (baseline T1), anesthetized and supine (T2), anesthetized after insufflation of the abdomen with carbon dioxide (CO2) (T3), anesthetized in steep Trendelenburg (T4), anesthetized in steep Trendelenburg at the end of the procedure (T5), anesthetized supine before awakening (T6), and 1 hr after awakening in the supine position (T7). RESULTS: On average, IOP was 13.3 ± 0.58 (mean ± se) mm Hg higher at the end of the period of steep Trendelenburg position (T5) compared with supine position T1 (P < 0.0001). The least square estimates for each time point in mm Hg were as follows: T1 = 15.7, T2 = 10.7, T3 = 14.6, T4 = 25.2, T5 = 29.0, T6 = 22.2, T7 = 17.0. Using univariate mixed effects models for the T1–T5 time periods, peak airway pressure, mean arterial blood pressure, ETco2, and time were significant predictors of the IOP increase, whereas age, body mass index, blood loss, volume of IV fluid administered, mean airway pressure, and desflurane concentration were not predictive. In T4–T5, which involved no significant positional or perioperative interventions, we performed a multivariate analysis to evaluate predictors of IOP increases. Surgical duration (in minutes) and ETco2 were the only significant variables predicting changes in IOP during stable and prolonged Trendelenburg positioning. On average, IOP increased 0.21 mm Hg per mm Hg increase in ETco2 after adjusting for time. An increase of 0.05 mm Hg in IOP per minute of surgery on average was observed during this period in the Trendelenburg position after adjusting for ETco2. CONCLUSIONS: IOP reached peak levels at the end of steep Trendelenburg position (T5), on average 13 mm Hg higher than the preanesthesia induction (T1) value. Surgical duration and ETco2 were the only significant predictors of IOP increase in the Trendelenburg position (T4–T5).

There is no dose-escalation response to dexamethasone (0.0625-1.0 mg/kg) in pediatric tonsillectomy or adenotonsillectomy patients for preventing vomiting, reducing pain, shortening time to first liquid intake, or the incidence of voice change

BACKGROUND: Tonsillectomy is associated with postoperative nausea and vomiting (PONV) if no prophylaxis is administered. Previous studies have shown that a single dose of dexamethasone decreases the incidence of PONV. The most effective dose of dexamethasone to affect clinical outcome is yet to be defined. METHODS: One-hundred-twenty-five children were enrolled in a double-blind, prospective, randomized, dose-escalating study of dexamethasone: 0.0625, 0.125, 0.25, 0.5, or 1 mg/kg, maximum dose 24 mg. Nonparametric ANOVA was used to analyze the incidence of vomiting by treatment group for 0 to ≤5 h, >5 to 24 h. The Cox Proportional Likelihood Ratio Test was used to compare the time of first vomit and time to first pain medication across treatment groups. RESULTS: There was no difference in the incidence of vomiting for the five escalating doses of dexamethasone in the time period. There were no differences in secondary outcomes (analgesic requirements, time to first liquid, and change in voice) across treatment groups. CONCLUSION: We conclude that the lowest dose of dexamethasone (0.0625 mg/kg) was as effective as the highest dose of dexamethasone (1.0 mg/kg) for preventing PONV or reducing the incidence of other secondary outcomes following tonsillectomy or adenotonsillectomy. There is no justification for the use of high-dose dexamethasone for the prevention of PONV in this cohort of children.

The new air-QTM intubating laryngeal airway for tracheal intubation in children with anticipated difficult airway: a case series: THE NEW AIR-QTM INTUBATING LARYNGEAL AIRWAY FOR ANTICIPATED DIFFICULT AIRWAY IN CHILDREN

The air‐Q intubating laryngeal airway (ILA) is a new supraglottic airway device which may overcome some limitations inherent to the classic laryngeal mask airway for tracheal intubation. We present a case series of patients with anticipated difficult airway in whom the air‐Q ILA was successfully used as a conduit for fiberoptic intubation.

A clinical evaluation of the intubating laryngeal airway as a conduit for tracheal intubation in children.

BACKGROUND:The air-Q™ Intubating Laryngeal Airway (ILA) (Cookgas LLC, Mercury Medical, Clearwater, FL) is a supraglottic airway device available in pediatric sizes, with design features to facilitate passage of cuffed tracheal tubes when used to guide tracheal intubation. We designed this prospective observational study of the ILA to assess the ease of its placement in paralyzed pediatric patients, determine its position and alignment to the larynx using a fiberoptic bronchoscope, gauge its efficacy as a conduit for fiberoptic intubation with cuffed tracheal tubes, and evaluate the ability to remove the ILA without dislodgement of the tracheal tube after successful tracheal intubation. METHODS:One hundred healthy children, aged 6 months to 8 years, ASA physical status I to II, and scheduled for elective surgery requiring general endotracheal anesthesia were enrolled in this prospective study. Based on the manufacturers guidelines, each patient received either a size 1.5 or 2.0 ILA according to their weight. The number of attempts for successful insertion, leak pressures, fiberoptic grade of view, number of attempts and time for tracheal intubation, time for ILA removal, and complications were recorded. RESULTS:ILA placement, fiberoptic tracheal intubation, and ILA removal were successful in all patients. The size 1.5 ILA cohort had significantly higher rates of epiglottic downfolding compared with the size 2.0 ILA cohort (P < 0.001), despite adequate ventilation variables. When comparing fiberoptic grade of view to weight, a moderate negative correlation was found (r = −0.41, P < 0.001), indicating that larger patients tended to have better fiberoptic grades of view. The size 1.5 ILA cohort had a significantly longer time to intubation (P = 0.04) compared with the size 2.0 ILA cohort. However, this difference may not be clinically significant because there was a large overlap of confidence bounds in the average times of the size 1.5 ILA (27.0 ± 13.0 seconds) and size 2.0 ILA cohorts (22.7 ± 6.9 seconds). When comparing weight to time to tracheal intubation, a weak correlation that was not statistically significant was found (r = −0.17, P = 0.09), showing that time to intubation did not differ significantly according to weight, despite higher fiberoptic grades in smaller patients. CONCLUSIONS:The ILA was easy to place and provided an effective conduit for tracheal intubation with cuffed tracheal tubes in children with normal airways. Additionally, removal of the ILA after successful intubation could be achieved quickly and without dislodgement of the tracheal tube. Because of the higher incidence of epiglottic downfolding in smaller patients, the use of fiberoptic bronchoscopy is recommended to assist with tracheal intubation through this device.

A randomized trial comparing the Ambu® Aura-i™ with the air-Q™ intubating laryngeal airway as conduits for tracheal intubation in children

To assess the clinical performance of the Ambu Aura‐i (Aura‐i) in children.

Teaching residents pediatric fiberoptic intubation of the trachea: Traditional fiberscope with an eyepiece versus a video-assisted technique using a fiberscope with an integrated camera

Background:The authors’ hypothesis was that a video-assisted technique should speed resident skill acquisition for flexible fiberoptic oral tracheal intubation (FI) of pediatric patients because the attending anesthesiologist can provide targeted instruction when sharing the view of the airway as the resident attempts intubation. Methods:Twenty Clinical Anesthesia year 2 residents, novices in pediatric FI, were randomly assigned to either the traditional group (traditional eyepiece FI) or the video group (video-assisted FI). One of two attending anesthesiologists supervised each resident during FI of 15 healthy children, aged 1–6 yr. The time from mask removal to confirmation of endotracheal tube placement by end-tidal carbon dioxide detection was recorded. Intubation attempts were limited to 3 min; up to three attempts were allowed. The primary outcome measure, time to success or failure, was compared between groups. Failure rate and number of attempts were also compared between groups. Results:Three hundred patient intubations were attempted; eight failed. On average, the residents in the video group were faster, were three times more likely to successfully intubate at any given time during an attempt, and required fewer attempts per patient compared to those in the traditional group. Conclusions:The video system seems to be superior for teaching residents fiberoptic intubation in children.

A Double-Blind Comparison of Intravenous Ondansetron and Placebo for Preventing Postoperative Emesis in 1- to 24- Month-Old Pediatric Patients After Surgery Under General Anesthesia

We assessed the efficacy and safety of ondansetron (0.1 mg/kg IV) prophylactically administered before surgery for prevention of postoperative vomiting (POV) in a double-blind, placebo-controlled study of 670 pediatric patients, 1- to 24-mo-old, undergoing elective surgery under general anesthesia. The study enrolled 335 children in each treatment group (ondansetron versus placebo). Significantly fewer children treated with ondansetron exhibited emesis or discontinued the study prematurely after surgery (ondansetron, 11%; placebo, 28%; odds ratio = 0.33; P < 0.0001). The number required to treat prophylactically with ondansetron to prevent POV was approximately six. Ondansetron treatment also resulted in fewer patients requiring rescue medication or assumed to have had rescue upon early discontinuation from the study during the postoperative period (ondansetron, 5%; placebo, 10%) and less emesis (0 of 6) after rescue medication when compared with placebo (7 of 21). The incidence of POV and other antiemetic effects of ondansetron were similar in children aged 1–12 mo and 13–24 mo and in children prospectively expected or not expected to require opioids as part of their anesthetic or analgesic management. Ondansetron was well tolerated; the incidence of adverse events considered possibly related to study drug was similar between treatment groups (ondansetron, 1.8%; placebo, 1.5%).

The addition of clonidine 2 μg·kg-1 does not enhance the postoperative analgesia of a caudal block using 0.125% bupivacaine and epinephrine 1: 200 000 in children: A prospective, double-blind, randomized study

Background : In this prospective, randomized, double‐blind study, we compared the efficacy of 0.125% bupivacaine and epinephrine 1 : 200 000 with and without clonidine 2 μg·kg−1 for ‘single shot’ pediatric caudal analgesia.

Prospective evaluation of the self-pressurized air-Q intubating laryngeal airway in children

Objectives:  To assess the clinical efficacy of the self‐pressurized air‐Q ILA™ (ILA‐SP).

A bronchoscopic, computer-assisted examination of the changes in dimension of the infant tracheal lumen with changes in head position: Implications for emergency airway management

Background Resuscitation guidelines caution against extreme extension or flexion of an infants head because tracheal obstruction may occur. No data support this recommendation. The authors therefore examined the dimensions of the tracheal lumen in neutral, extended, and flexed head positions in infants undergoing general endotracheal anesthesia for elective surgery. Methods Eighteen healthy full‐term infants were studied. A flexible fiberoptic bronchoscope was passed through a previously inserted endotracheal tube and positioned above the cricoid cartilage. Video recordings were taken in each of three head positions. Recordings were analyzed by an investigator blinded to head position. A computer‐digitized technique was used to measure anterior‐posterior and lateral dimensions and cross‐sectional area. Data were analyzed using paired t tests and sign tests. Results No significant differences in mean tracheal dimensions with changes in head position were found. No infant had complete tracheal obstruction. Infants were equally as likely to have a small increase as they were to have a small decrease in tracheal dimension with changes in head position. Conclusions Despite the belief that infants and neonates have obstruction at the level of the trachea with extreme positions of the head, the authors were unable to demonstrate this phenomenon.