Body Habitus and Dynamic Surgical Conditions Independently Impair Pulmonary Mechanics during Robotic-assisted Laparoscopic Surgery.

BACKGROUND: Body habitus, pneumoperitoneum, and Trendelenburg positioning may each independently impair lung mechanics during robotic laparoscopic surgery. This study hypothesized that increasing body mass index is associated with more mechanical strain and alveolar collapse, and these impairments are exacerbated by pneumoperitoneum and Trendelenburg positioning. METHODS: This cross-sectional study measured respiratory flow, airway pressures, and esophageal pressures in 91 subjects with body mass index ranging from 18.3 to 60.6 kg/m2. Pulmonary mechanics were quantified at four stages: (1) supine and level after intubation, (2) with pneumoperitoneum, (3) in Trendelenburg docked with the surgical robot, and (4) level without pneumoperitoneum. Subjects were stratified into five body mass index categories (less than 25, 25 to 29.9, 30 to 34.9, 35 to 39.9, and 40 or higher), and respiratory mechanics were compared over surgical stages using generalized estimating equations. The optimal positive end-expiratory pressure settings needed to achieve positive end-expiratory transpulmonary pressures were calculated. RESULTS: At baseline, transpulmonary driving pressures increased in each body mass index category (1.9 ± 0.5 cm H2O; mean difference ± SD; P < 0.006), and subjects with a body mass index of 40 or higher had decreased mean end-expiratory transpulmonary pressures compared with those with body mass index of less than 25 (-7.5 ± 6.3 vs. -1.3 ± 3.4 cm H2O; P < 0.001). Pneumoperitoneum and Trendelenburg each further elevated transpulmonary driving pressures (2.8 ± 0.7 and 4.7 ± 1.0 cm H2O, respectively; P < 0.001) and depressed end-expiratory transpulmonary pressures (-3.4 ± 1.3 and -4.5 ± 1.5 cm H2O, respectively; P < 0.001) compared with baseline. Optimal positive end-expiratory pressure was greater than set positive end-expiratory pressure in 79% of subjects at baseline, 88% with pneumoperitoneum, 95% in Trendelenburg, and ranged from 0 to 36.6 cm H2O depending on body mass index and surgical stage. CONCLUSIONS: Increasing body mass index induces significant alterations in lung mechanics during robotic laparoscopic surgery, but there is a wide range in the degree of impairment. Positive end-expiratory pressure settings may need individualization based on body mass index and surgical conditions.

Changing Anesthesia Block Allocations Improves Endoscopy Suite Efficiency.

Non-operating room anesthesia (NORA) has grown and continues to expand as a proportion of all anesthesia practice in the United States [1, 2]. While many management processes have been adapted for NORA from the traditional operating room, it is still unclear what scheduling paradigm will maximize efficiency of resource utilization in this arena. In this study, we investigate the impact of tactical a shift from a shared group to individual, provider-specific block allocations for available anesthesia time in an endoscopy suite for adult patients undergoing elective endoscopy procedures at an academic hospital. Using a retrospective and prospective analysis, we measured elective time-in-block; elective time out-of-block; under-utilized (opportunity and non-opportunity unused) time; over-utilized time; and case tardiness to determine operational efficiency and clinical productivity. Over the study period, the monthly caseload remained constant. Elective time in block increased by 156% (p < 0.0001) and elective time out of block decreased by 38% (p < 0.0001). Opportunity unused time decreased by 28% (p < 0.0001) and productivity increased by 51% (p < 0.0001). Neither over-utilized time nor case tardiness showed a significant change after the intervention. Despite the evidence base supporting traditional approaches to anesthesia block allocation involving group block allocation and non-sequential case scheduling, we have demonstrated an advantage to individual block allocation in a GI endoscopy setting. This sequential case scheduling highlights how tactical decisions in NORA environments may require a rethinking of many practices that anesthesiologists have brought with them from the traditional OR. Using these efficiency and productivity metrics, further adjustments to scheduling practices should be investigated, and connecting these metrics to other systems outcomes, such as financial productivity, is an important next step as NORA services expand into the future.

A System-Wide Approach to Physician Efficiency and Utilization Rates for Non-Operating Room Anesthesia Sites.

There has been little in the development or application of operating room (OR) management metrics to non-operating room anesthesia (NORA) sites. This is in contrast to the well-developed management framework for the OR management. We hypothesized that by adopting the concept of physician efficiency, we could determine the applicability of this clinical productivity benchmark for physicians providing services for NORA cases at a tertiary care center. We conducted a retrospective data analysis of NORA sites at an academic, rural hospital, including both adult and pediatric patients. Using the time stamps from WiseOR® (Palo Alto, CA), we calculated site utilization and physician efficiency for each day. We defined scheduling efficiency (SE) as the number of staffed anesthesiologists divided by the number of staffed sites and stratified the data into three categories (SE < 1, SE = 1, and SE >1). The mean physician efficiency was 0.293 (95% CI, [0.281, 0.305]), and the mean site utilization was 0.328 (95% CI, [0.314, 0.343]). When days were stratified by scheduling efficiency (SE < 1, =1, or >1), we found differences between physician efficiency and site utilization. On days where scheduling efficiency was less than 1, that is, there are more sites than physicians, mean physician efficiency (95% CI, [0.326, 0.402]) was higher than mean site utilization (95% CI, [0.250, 0.296]). We demonstrate that scheduling efficiency vis-à-vis physician efficiency as an OR management metric diverge when anesthesiologists travel between NORA sites. When the opportunity to scale operational efficiencies is limited, increasing scheduling efficiency by incorporating different NORA sites into a "block" allocation on any given day may be the only suitable tactical alternative.

The neuroendocrine stress response compensates for suppression of insulin secretion by volatile anesthetic agents: An observational study.

Alterations in perioperative metabolic function, particularly hyperglycemia, are associated with increased post-operative complications, even in patients without preexisting metabolic abnormalities. Anesthetic medications and the neuroendocrine stress response to surgery may both contribute to altered energy metabolism through impaired glucose and insulin homeostasis but the discrete pathways involved are unclear. Prior human studies, though informative, have been limited by analytic sensitivity or technique, preventing resolution of underlying mechanisms. We hypothesized that general anesthesia with a volatile agent would suppress basal insulin secretion without altering hepatic insulin extraction, and that surgical stress would promote hyperglycemia through gluconeogenesis, lipid oxidation, and insulin resistance. In order to address these hypotheses, we conducted an observational study of subjects undergoing multi-level lumbar surgery with an inhaled anesthetic agent. We measured circulating glucose, insulin, c-peptide, and cortisol frequently throughout the perioperative period and analyzed the circulating metabolome in a subset of these samples. We found volatile anesthetic agents suppress basal insulin secretion and uncouple glucose-stimulated insulin secretion. Following surgical stimulus, this inhibition disappeared and there was gluconeogenesis with selective amino acid metabolism. No robust evidence of lipid metabolism or insulin resistance was observed. These results show that volatile anesthetic agents suppress basal insulin secretion, which results in reduced glucose metabolism. The neuroendocrine stress response to surgery ameliorates the inhibitory effect of the volatile agent on insulin secretion and glucose metabolism, promoting catabolic gluconeogenesis. A better understanding of the complex metabolic interaction between anesthetic medications and surgical stress is needed to inform design of clinical pathways aimed at improving perioperative metabolic function.

Effects of obesity, pneumoperitoneum, and body position on mechanical power of intraoperative ventilation: an observational study.

Mechanical power can describe the complex interaction between the respiratory system and the ventilator and may predict lung injury or pulmonary complications, but the power associated with injury of healthy human lungs is unknown. Body habitus and surgical conditions may alter mechanical power but the effects have not been measured. In a secondary analysis of an observational study of obesity and lung mechanics during robotic laparoscopic surgery, we comprehensively quantified the static elastic, dynamic elastic, and resistive energies comprising mechanical power of ventilation. We stratified by body mass index (BMI) and examined power at four surgical stages: level after intubation, with pneumoperitoneum, in Trendelenburg, and level after releasing the pneumoperitoneum. Esophageal manometry was used to estimate transpulmonary pressures. Mechanical power of ventilation and its bioenergetic components increased over BMI categories. Respiratory system and lung power were nearly doubled in subjects with class 3 obesity compared with lean at all stages. Power dissipated into the respiratory system was increased with class 2 or 3 obesity compared with lean. Increased power of ventilation was associated with decreasing transpulmonary pressures. Body habitus is a prime determinant of increased intraoperative mechanical power. Obesity and surgical conditions increase the energies dissipated into the respiratory system during ventilation. The observed elevations in power may be related to tidal recruitment or atelectasis, and point to specific energetic features of mechanical ventilation of patients with obesity that may be controlled with individualized ventilator settings.NEW & NOTEWORTHY Mechanical power describes the complex interaction between a patient's lungs and the ventilator and may be useful in predicting lung injury. However, its behavior in obesity and during dynamic surgical conditions is not understood. We comprehensively quantified ventilation bioenergetics and effects of body habitus and common surgical conditions. These data show body habitus is a prime determinant of intraoperative mechanical power and provide quantitative context for future translation toward a useful perioperative prognostic measurement.

Using performance frontiers to differentiate elective and capacity-based surgical services.

BACKGROUND: Acute care surgery (ACS) model of care delivery has many benefits. However, since the ACS surgeon has limited control over the volume, timing, and complexity of cases, traditional metrics of operating room (OR) efficiency almost always measure ACS service as "inefficient." The current study examines an alternative method-performance fronts-of evaluating changes in efficiency and tests the following hypotheses: (1) in an institution with a robust ACS service, performance front methodology is superior to traditional metrics in evaluating OR throughput/efficiency, and (2) introduction of an ACS service with block time allocation will improve OR throughput/efficiency. METHODS: Operating room metrics 1-year pre-ACS implementation and post-ACS implementation were collected. Overall OR efficiency was calculated by mean case volumes for the entire OR and ACS and general surgery (GS) services individually. Detailed analysis of these two specific services was performed by gathering median monthly minutes-in block, out of block, after hours, and opportunity unused. The two services were examined using a traditional measure of efficiency and the "fronts" method. Services were compared with each other and also pre-ACS implementation and post-ACS implementation. RESULTS: Overall OR case volumes increased by 5% (999 ± 50 to 1,043 ± 46: p < 0.05) with almost all of the increase coming through ACS (27 ± 4 to 68 ± 16: p < 0.05). By traditional metrics, ACS had significantly worse median efficiency versus GS in both periods: pre (0.67 [0.66-0.71] vs. 0.80 [0.78-0.81]) and post (0.75 [0.53-0.77] vs. 0.83 [0.84-0.85]) (p < 0.05). As compared with the pre, GS efficiency improved significantly in post (p < 0.05), but ACS efficiency remained unchanged (p > 0.05). The alternative fronts chart demonstrated the more accurate picture with improved efficiency observed for GS, ACS, and combined. CONCLUSION: In an institution with a busy ACS service, the alternative fronts methodology offers a more accurate evaluation of OR efficiency. The provision of an OR for the ACS service improves overall throughput/efficiency.

Applying Performance Frontiers in Operating Room Management: A Tutorial Using Data From an Academic Medical Center.

Although the primary goal of operating room (OR) management is to minimize inefficiencies, it may be difficult for OR managers to track metrics when one extrapolates possible scenarios across every OR on a daily basis. With the ability to visualize the statistical relationships to help simplify the analysis of large datasets, a more elaborate efficiency framework can be established using Pareto optimality (or performance frontiers), a multicriteria framework that includes variables that serve as proxies for a variety of outcomes. Applied to OR management, performance frontiers allow for the evaluation of common and well-understood issues of under- and over-utilized time.

Nonoperating Room Anesthesia Tardiness.

Tardiness in the operating room has been shown to decline in the day as a result of operational decisions on the day of surgery. This article studies nonoperating room anesthesia (NORA) tardiness at the University of Vermont Medical Center in cases performed in the 2015 calendar year. Tardiness was measured by subtracting actual start times from extracted scheduled start times for each NORA services line. On average, tardiness in NORA sites increased as the day progressed, with the exception of diagnostic radiology. This is likely due to limited tactical and operational opportunities to improve workflow.