Economic and Environmental Considerations During Low Fresh Gas Flow Volatile Agent Administration After Change to a Nonreactive Carbon Dioxide Absorbent.

BACKGROUND: Reducing fresh gas flow (FGF) during general anesthesia reduces costs by decreasing the consumption of volatile anesthetics and attenuates their contribution to greenhouse gas pollution of the environment. The sevoflurane FGF recommendations in the Food and Drug Administration package insert relate to concern over potential toxicity from accumulation in the breathing circuit of compound A, a by-product of the reaction of the volatile agent with legacy carbon dioxide absorbents containing strong alkali such as sodium or potassium hydroxide. Newer, nonreactive absorbents do not produce compound A, making such restrictions moot. We evaluated 4 hypotheses for sevoflurane comparing intervals before and after converting from a legacy absorbent (soda lime) to a nonreactive absorbent (Litholyme): (1) intraoperative FGF would be reduced; (2) sevoflurane consumption per minute of volatile agent administration would be reduced; (3) cost savings due to reduced sevoflurane consumption would (modestly) exceed the incremental cost of the premium absorbent; and (4) residual wastage in discarded sevoflurane bottles would be <1%. METHODS: Inspired carbon dioxide (PICO2), expired carbon dioxide, oxygen, air, and nitrous oxide FGF, inspired volatile agent concentrations (FiAgent), and liquid volatile agent consumption were extracted from our anesthesia information management system for 8 4 week intervals before and after the absorbent conversion. Anesthesia providers were notified by e-mail and announcements at Grand Rounds about the impending change and were encouraged to reduce their average intraoperative sevoflurane FGF to 1.25 L/min. Personalized e-mail reports were sent every 4 weeks throughout the study period regarding the average intraoperative FGF (i.e., from surgery begin to surgery end) for each agent. Batch means methods were used to compare FGF, volatile agent consumption, net cost savings, and residual sevoflurane left in bottles to be discarded in the trash after filling vaporizers. The time from reaching a PICO2 = 3 mm Hg for 3 minutes until agent exhaustion (PICO2 = 5 mm Hg for 5 minutes) was evaluated. RESULTS: A total of N = 20,235 cases were analyzed (80.2% sevoflurane, 15.1% desflurane, and 4.7% isoflurane). Intraoperative FGF was reduced for cases in which sevoflurane was administered by 435 mL/min (95% confidence interval [CI], 391 to 479 mL/min; P < 10). Hypothesis 1 was accepted. Sevoflurane consumption per minute of administration decreased by 0.039 mL/min (95% CI, 0.029 to 0.049 mL/min; P < 10) after the change to the nonreactive absorbent. Hypothesis 2 was accepted. The difference in mean cost for the sum of the sevoflurane and absorbent purchases for each of the 10 4-week intervals before and after the absorbent switch was -$293 per 4-week interval (95% CI, -$2853 to $2266; P = 0.81). Hypothesis 3 was rejected. The average amount of residual sevoflurane per bottle was 0.67 ± 0.06 mL (95% CI, 0.54 to 0.81 mL per bottle; P < 10 vs 2.5 mL). Hypothesis 4 was accepted. Once the PICO2 reached 3 mm Hg for at least 3 consecutive minutes, the absorbent became exhausted within 95 minutes in most (i.e., >50%) canisters. CONCLUSIONS: We showed that an anesthesia department can transition to a premium, nonreactive carbon dioxide absorbent in a manner that is at least cost neutral by reducing FGF below the lower flow limits recommended in the sevoflurane package insert. This was achieved, in part, by electronically monitoring PICO2, automatically notifying the anesthesia technicians when to change the absorbent, and by providing personalized feedback via e-mail to the anesthesia providers.

The HYSLAR trial: a prospective randomized controlled trial of the use of a restrictive fluid regimen with 3% hypertonic saline versus lactated Ringers in patients undergoing pancreaticoduodenectomy.

OBJECTIVE: This study was designed to determine whether the volume and type of fluid administered for pancreaticoduodenectomy impacts postoperative outcomes. BACKGROUND: Three percent hypertonic saline (HYS) has been suggested as a means of reducing the volume of fluid required to sustain tissue perfusion in the perioperative period. METHODS: Between May 2011 and November 2013, patients undergoing pancreaticoduodenectomy were enrolled in an institutional review board-approved, single-center, prospective, parallel, randomized controlled trial (NCT 01428050), comparing lactated Ringers (LAR) (15 mL/kg/hr LAR intraoperation, 2 mL/kg/hr LAR postoperation) with HYS (9 mL/kg/hr LAR and 1 mL/kg/hr HYS intraoperation, 1 mL/kg/hr HYS postoperation). RESULTS: A total of 264 patients were randomized. Demographic variables between groups were similar. The HYS patients had a significantly reduced net fluid balance (65 vs 91 mL/kg, P = 0.02). The overall complication rate was reduced in the HYS group (43% vs 54%), with a relative risk of 0.79 [95% confidence interval (CI), 0.62-1.02; P = 0.073], factoring stratification for pancreas texture. After adjustment for age and weight, the relative risk was 0.75 [95% CI (0.58-0.96); P = 0.023]. The total number of complications was significantly reduced in the HYS group (93 vs 123), with an incidence rate ratio of 0.74 [95% CI (0.56-0.97); P = 0.027]. After adjustment for age and weight, the incidence rate ratio was 0.69 [95% CI (0.52-0.90); P = 0.0068]. Reoperations, length of stay, readmissions, and 90-day mortality were similar between groups. CONCLUSIONS: A moderately restrictive fluid regimen with HYS resulted in a statistically significant 25% reduction in complications when adjusted for age, weight, and pancreatic texture.

Correlation of histopathology, urinary biomarkers, and gene expression responses following hexachloro-1:3-butadiene-induced acute nephrotoxicity in male Hanover Wistar rats: a 28-day time course study.

Hexachloro-1:3-butadiene (HCBD) causes segment-specific injury to the proximal renal tubule. A time course study of traditional and more recently proposed urinary biomarkers was performed in male Hanover Wistar rats receiving a single intraperitoneal (ip) injection of 45 mg/kg HCBD. Animals were killed on days 1, 2, 3, 4, 5, 6, 7, 10, 14, and 28 postdosing and the temporal response of renal biomarkers was characterized using kidney histopathology, urinary and serum biochemistry, and gene expression. Histopathologic evidence of tubular degeneration was seen from day 1 until day 3 postdosing and correlated with increased urinary levels of α-glutathione S-transferase (α-GST), albumin, glucose, and kidney injury molecule-1 (KIM-1), and increased gene expression of KIM-1, NAD(P)H dehydrogenase, quinone 1, and heme oxygenase (decycling) 1. Histopathologic evidence of tubular regeneration was seen from day 2 postdosing and correlated with raised levels of urinary KIM-1 and osteopontin and increased gene expression of KIM-1 and annexin A7. Traditional renal biomarkers generally demonstrated low sensitivity. It is concluded that in rat proximal tubular injury, measurement of a range of renal biomarkers, in conjunction with gene expression analysis, provides an understanding of the extent of degenerative changes induced in the kidney and the process of regeneration.

Autotriggering during pressure support ventilation due to cardiogenic oscillations.

Newer generation anesthesia machines are equipped with a pressure support mode of ventilation, which can be used to support spontaneous ventilation in anesthetized patients. The Drager Apollo anesthesia machine uses an inspiratory limb hot-wire flow sensor to measure inspiratory flow rates. Detected flow rates that exceed the pressure support flow trigger will trigger pressure support breaths (Internal communication document. Drager Medical, 2007). In the case we are presenting, cardiac oscillations produced inspiratory flow rates that exceeded the flow trigger and autotriggered pressure support breaths. Autotriggering could be suppressed by increasing the trigger threshold or the positive end-expiratory pressure setting.

Experience Is the Teacher of All Things: Prior Participation in Anesthesiology OSCEs Enhances Communication of Treatment Options With Simulated High-Risk Patients.

BACKGROUND: The objective of this study was to investigate whether previous experiences within an anesthesiology-based Objective Structured Clinical Examination (OSCE) assessing communication and professionalism skills was associated with improved performance in a subsequent anesthesiology-based OSCE scenario. METHODS: This retrospective multi-center study used the performance data of 44 Post Graduate Year 4 clinical anesthesia residents from 3 US anesthesiology residency programs on an OSCE scenario that assessed the residents' effectiveness of discussing anesthesiology-specific treatment options with a high-risk patient. Residents from 2 of the programs had no prior anesthesiology-based OSCE experience. Residents from the third program had previously participated in 4 separate multi-scenario anesthesiology-based OSCE sessions in the 2 years prior to this study. Participating residents completed the same scenario at their respective institutions' simulation center. Ten performances were randomly selected for double rating to assess the interrater reliability of the assessments. Interrater reliability was good for the scenario (intraclass correlation coefficient = 0.66, 95% confidence interval = 0.12-0.90). Performance difference between groups with different OSCE experience status were examined using an independent sample t test, with a Wilcoxon-Mann-Whitney test as a sensitivity analysis. RESULTS: Independent sample t test found prior OSCE experience was significantly associated with higher performance scores (t = 2.53, P = .02). The Wilcoxon-Mann-Whitney test result confirmed this finding (z = 3.28, P = .001). CONCLUSIONS: Findings from this study provide preliminary evidence that anesthesiology-based OSCE experience is associated with improved performance in an OSCE scenario, specifically regarding discussions of treatment options with high-risk patients.

Anesthetic implications for patients with rate-responsive pacemakers.

One hundred thousand adults and children in the United States receive pacemakers each year, of which 85% are rate-responsive pacemakers (RRPs). Recent advances in the fields of computer programming and computer chip technology have led to the myriad development of RRPs, which contain sensors that automatically adjust the pacing rate to match the physiologic changes that occur during physical exertion. Because patients with RRPs may experience heart rate changes in the operating room due to ''normal'' sensor function, anesthesiologists must be aware of the new developments in RRP sensor technology to properly manage these patients. Increases in respiratory rate and tidal volume as well as the use of electrocautery have been reported to accelerate the paced rate of pacemakers with minute ventilation sensors. Likewise, patient movement and saws that produce vibrations can accelerate the paced rate of patients with piezoelectric crystal sensors. This paper discusses the history of pacemaker development, reviews the currently used RRP sensors, and recommends procedures for the perioperative management of these patients. Knowledge of sensor type and factors that stimulate them will help the anesthesiologist understand the cause of these changes so that he will be able to manage clinically significant hemodynamic changes due to RRP sensor activation.

Using the capnograph to confirm lung isolation when using a bronchial blocker.

The endotracheal tube and bronchial blocker combination is an accepted lung isolation technique used during thoracic surgery. A reliable and inexpensive method of confirming lung isolation that uses capnographic monitoring of the bronchial blocker central lumen is presented. As the bronchial blocker balloon is inflated, lung isolation is confirmed when the normal respiratory variation of carbon dioxide (CO(2)) is replaced by a persistent plateau CO(2) waveform.