Computer vision digitization of smartphone images of anesthesia paper health records from low-middle income countries.

BACKGROUND: In low-middle income countries, healthcare providers primarily use paper health records for capturing data. Paper health records are utilized predominately due to the prohibitive cost of acquisition and maintenance of automated data capture devices and electronic medical records. Data recorded on paper health records is not easily accessible in a digital format to healthcare providers. The lack of real time accessible digital data limits healthcare providers, researchers, and quality improvement champions to leverage data to improve patient outcomes. In this project, we demonstrate the novel use of computer vision software to digitize handwritten intraoperative data elements from smartphone photographs of paper anesthesia charts from the University Teaching Hospital of Kigali. We specifically report our approach to digitize checkbox data, symbol-denoted systolic and diastolic blood pressure, and physiological data. METHODS: We implemented approaches for removing perspective distortions from smartphone photographs, removing shadows, and improving image readability through morphological operations. YOLOv8 models were used to deconstruct the anesthesia paper chart into specific data sections. Handwritten blood pressure symbols and physiological data were identified, and values were assigned using deep neural networks. Our work builds upon the contributions of previous research by improving upon their methods, updating the deep learning models to newer architectures, as well as consolidating them into a single piece of software. RESULTS: The model for extracting the sections of the anesthesia paper chart achieved an average box precision of 0.99, an average box recall of 0.99, and an mAP0.5-95 of 0.97. Our software digitizes checkbox data with greater than 99% accuracy and digitizes blood pressure data with a mean average error of 1.0 and 1.36 mmHg for systolic and diastolic blood pressure respectively. Overall accuracy for physiological data which includes oxygen saturation, inspired oxygen concentration and end tidal carbon dioxide concentration was 85.2%. CONCLUSIONS: We demonstrate that under normal photography conditions we can digitize checkbox, blood pressure and physiological data to within human accuracy when provided legible handwriting. Our contributions provide improved access to digital data to healthcare practitioners in low-middle income countries.

Mobile health supported multi-domain recovery trajectories after major arthroplasty or spine surgery: a pilot feasibility and usability study.

BACKGROUND: Recovery after surgery intersects physical, psychological, and social domains. In this study we aim to assess the feasibility and usability of a mobile health application called PositiveTrends to track recovery in these domains amongst participants undergoing hip, knee arthroplasty or spine surgery. Our secondary aim was to generate procedure-specific, recovery trajectories within the pain and medication, psycho-social and patient-reported outcomes domain. METHODS: Prospective, observational study in participants greater than eighteen years of age. Data was collected prior to and up to one hundred and eighty days after completion of surgery within the three domains using PositiveTrends. Feasibility was assessed using participant response rates from the PositiveTrends app. Usability was assessed quantitatively using the System Usability Scale. Heat maps and effect plots were used to visualize multi-domain recovery trajectories. Generalized linear mixed effects models were used to estimate the change in the outcomes over time. RESULTS: Forty-two participants were enrolled over a four-month recruitment period. Proportion of app responses was highest for participants who underwent spine surgery (median = 78, range = 36-100), followed by those who underwent knee arthroplasty (median = 72, range = 12-100), and hip arthroplasty (median = 62, range = 12-98). System Usability Scale mean score was 82 ± 16 at 180 days postoperatively. Function improved by 8 and 6.4 points per month after hip and knee arthroplasty, respectively. In spine participants, the Oswestry Disability Index decreased by 1.4 points per month. Mood improved in all three cohorts, however stress levels remained elevated in spine participants. Pain decreased by 0.16 (95% Confidence Interval: 0.13-0.20, p < 0.001), 0.25 (95% CI: 0.21-0.28, p < 0.001) and 0.14 (95% CI: 0.12-0.15, p < 0.001) points per month in hip, knee, and spine cohorts respectively. There was a 10.9-to-40.3-fold increase in the probability of using no medication for each month postoperatively. CONCLUSIONS: In this study, we demonstrate the feasibility and usability of PositiveTrends, which can map and track multi-domain recovery trajectories after major arthroplasty or spine surgery.

Correction: Academic global surgical competencies: A modified Delphi consensus study.

[This corrects the article DOI: 10.1371/journal.pgph.0002102.].

Academic global surgical competencies: A modified Delphi consensus study.

Academic global surgery is a rapidly growing field that aims to improve access to safe surgical care worldwide. However, no universally accepted competencies exist to inform this developing field. A consensus-based approach, with input from a diverse group of experts, is needed to identify essential competencies that will lead to standardization in this field. A task force was set up using snowball sampling to recruit a broad group of content and context experts in global surgical and perioperative care. A draft set of competencies was revised through the modified Delphi process with two rounds of anonymous input. A threshold of 80% consensus was used to determine whether a competency or sub-competency learning objective was relevant to the skillset needed within academic global surgery and perioperative care. A diverse task force recruited experts from 22 countries to participate in both rounds of the Delphi process. Of the n = 59 respondents completing both rounds of iterative polling, 63% were from low- or middle-income countries. After two rounds of anonymous feedback, participants reached consensus on nine core competencies and 31 sub-competency objectives. The greatest consensus pertained to competency in ethics and professionalism in global surgery (100%) with emphasis on justice, equity, and decolonization across multiple competencies. This Delphi process, with input from experts worldwide, identified nine competencies which can be used to develop standardized academic global surgery and perioperative care curricula worldwide. Further work needs to be done to validate these competencies and establish assessments to ensure that they are taught effectively.

Global competency impact of sustained remote international engagement for students.

BACKGROUND: To provide just equity in academic exchange, as well as to reduce prohibitive travel cost and address environmental concerns, the past paradigm of international student exchange has fundamentally shifted from one directional travel to mutually beneficial bidirectional remote communication between students all over the globe. Current analysis aims to quantify cultural competency and evaluate academic outcomes. METHODS: Sixty students half from the US and half from Rwanda grouped in teams of 4 engaged in a nine-month project-focused relationship. Cultural competency was evaluated prior to project initiation and six months after completion of the project. Student perspective of project development was analyzed weekly and final academic outcome was evaluated. RESULTS: Change in cultural competency was not significant; however, students did identify satisfaction in team interaction and academic outcomes were achieved. CONCLUSION: A single remote exchange between students in two countries may not be transformative but it can provide cultural enrichment and successful academic project outcome and may serve to enhance cultural curiosity.

Prolonged Opioid Use and Pain Outcome and Associated Factors after Surgery under General Anesthesia: A Prospective Cohort Association Multicenter Study.

BACKGROUND: There is insufficient prospective evidence regarding the relationship between surgical experience and prolonged opioid use and pain. The authors investigated the association of patient characteristics, surgical procedure, and perioperative anesthetic course with postoperative opioid consumption and pain 3 months postsurgery. The authors hypothesized that patient characteristics and intraoperative factors predict opioid consumption and pain 3 months postsurgery. METHODS: Eleven U.S. and one European institution enrolled patients scheduled for spine, open thoracic, knee, hip, or abdominal surgery, or mastectomy, in this multicenter, prospective observational study. Preoperative and postoperative data were collected using patient surveys and electronic medical records. Intraoperative data were collected from the Multicenter Perioperative Outcomes Group database. The association between postoperative opioid consumption and surgical site pain at 3 months, elicited from a telephone survey conducted at 3 months postoperatively, and demographics, psychosocial scores, pain scores, pain management, and case characteristics, was analyzed. RESULTS: Between September and October 2017, 3,505 surgical procedures met inclusion criteria. A total of 1,093 cases were included; 413 patients were lost to follow-up, leaving 680 (64%) for outcome analysis. Preoperatively, 135 (20%) patients were taking opioids. Three months postsurgery, 96 (14%) patients were taking opioids, including 23 patients (4%) who had not taken opioids preoperatively. A total of 177 patients (27%) reported surgical site pain, including 45 (13%) patients who had not reported pain preoperatively. The adjusted odds ratio for 3-month opioid use was 18.6 (credible interval, 10.3 to 34.5) for patients who had taken opioids preoperatively. The adjusted odds ratio for 3-month surgical site pain was 2.58 (1.45 to 4.4), 4.1 (1.73 to 8.9), and 2.75 (1.39 to 5.0) for patients who had site pain preoperatively, knee replacement, or spine surgery, respectively. CONCLUSIONS: Preoperative opioid use was the strongest predictor of opioid use 3 months postsurgery. None of the other variables showed clinically significant association with opioid use at 3 months after surgery.

Investigating the Association Between a Risk-Directed Prophylaxis Protocol and Postoperative Nausea and Vomiting: Validation in a Low-Income Setting.

BACKGROUND: The efficacy of postoperative nausea and vomiting (PONV) prevention protocols in low-income countries is not well known. Different surgical procedures, available medications, and co-occurring diseases imply that existing protocols may need validation in these settings. We assessed the association of a risk-directed PONV prevention protocol on the incidence of PONV and short-term surgical outcomes in a teaching hospital in Rwanda. METHODS: We compared the incidence of PONV during the first 48 hours postoperatively before (April 1, 2019-June 30, 2019; preintervention) and immediately after (July 1, 2019-September 30, 2019; postintervention) implementing an Apfel score-based PONV prevention strategy in 116 adult patients undergoing elective open abdominal surgery at Kigali University Teaching Hospital in Rwanda. Secondary outcomes included time to first oral intake, hospital length of stay, and rate of wound dehiscence. Interrupted time series analyses were performed to assess the associated temporal slopes of the outcome before and immediately after implementation of the risk-directed PONV prevention protocol. RESULTS: Compared to just before the intervention, there was no change in the odds of PONV at the beginning of the postintervention period (odds ratio [OR], 0.23; 95% confidence interval [CI], 0.05-1.01). There was a decreasing trend in the odds of nausea (OR, 0.60; 95% CI, 0.36-0.97) per month. However, there was no difference in the incidence of nausea immediately after implementation of the protocol (OR, 0.96; 95% CI, 0.25-3.72) or in the slope between preintervention and postintervention periods (OR, 1.48; 95% CI, 0.60-3.65). In contrast, there was no change in the odds of vomiting during the preintervention period (OR, 1.01; 95% CI, 0.61-1.67) per month. The odds of vomiting decreased at the beginning of the postintervention period compared to just before (OR, 0.10; 95% CI, 0.02-0.47; P = .004). Finally, there was a significant decrease in the average time to first oral intake (estimated 14 hours less; 95% CI, -25 to -3) when the protocol was first implemented, after adjusting for confounders; however, there was no difference in the slope of the average time to first oral intake between the 2 periods ( P = .44). CONCLUSIONS: A risk-directed PONV prophylaxis protocol was associated with reduced vomiting and time to first oral intake after implementation. There was no substantial difference in the slopes of vomiting incidence and time to first oral intake before and after implementation.

Digitization of Symbol-Denoted Blood Pressure Data From Intraoperative Paper Health Records in a Low-Middle-Income Country Using Deep Image Segmentation and Associated Postoperative Outcomes: A Feasibility Study.

BACKGROUND: In low-middle-income countries (LMICs), perioperative clinical information is almost universally collected on paper health records (PHRs). The lack of accessible digital databases limits LMICs in leveraging data to predict and improve patient outcomes after surgery. In this feasibility study, our aims were to: (1) determine the detection performance and prediction error of the U-Net deep image segmentation approach for digitization of hand-drawn blood pressure symbols from an image of the intraoperative PHRs and (2) evaluate the association between deep image segmentation-derived blood pressure parameters and postoperative mortality and length of stay. METHODS: A smartphone mHealth platform developed by our team was used to capture images of completed intraoperative PHRs. A 2-stage deep image segmentation modeling approach was used to create 2 separate segmentation masks for systolic blood pressure (SBP) and diastolic blood pressure (DBP). Iterative postprocessing was utilized to convert the segmentation mask results into numerical SBP and DBP values. Detection performance and prediction errors were evaluated for the U-Net models by comparison with ground-truth values. Using multivariate regression analysis, we investigated the association of deep image segmentation-derived blood pressure values, total time spent in predefined blood pressure ranges, and postoperative outcomes including in-hospital mortality and length of stay. RESULTS: A total of 350 intraoperative PHRs were imaged following surgery. Overall accuracy was 0.839 and 0.911 for SBP and DBP symbol detections, respectively. The mean error rate and standard deviation for the difference between the actual and predicted blood pressure values were 2.1 ± 4.9 and -0.8 ± 3.9 mm Hg for SBP and DBP, respectively. Using the U-Net model-derived blood pressures, minutes of time where DBP <50 mm Hg (odds ratio [OR], 1.03; CI, 1.01-1.05; P = .003) was associated with an increased in-hospital mortality. In addition, increased cumulative minutes of time with SBP between 80 and 90 mm Hg was significantly associated with a longer length of stay (incidence rate ratio, 1.02 [1.0-1.03]; P < .05), while increased cumulative minutes of time where SBP between 140 and 160 mm Hg was associated with a shorter length of stay (incidence rate ratio, 0.9 [0.96-0.99]; P < .05). CONCLUSIONS: In this study, we report our experience with a deep image segmentation model for digitization of symbol-denoted blood pressure from intraoperative anesthesia PHRs. Our data support further development of this novel approach to digitize PHRs from LMICs, to provide accessible, curated, and reproducible data for both quality improvement- and outcome-based research.

Practice Patterns and Variability in Intraoperative Opioid Utilization: A Report From the Multicenter Perioperative Outcomes Group.

BACKGROUND: Opioids remain the primary mode of analgesia intraoperatively. There are limited data on how patient, procedural, and institutional characteristics influence intraoperative opioid administration. The aim of this retrospective, longitudinal study from 2012 to 2016 was to assess how intraoperative opioid dosing varies by patient and clinical care factors and across multiple institutions over time. METHODS: Demographic, surgical procedural, anesthetic technique, and intraoperative analgesia data as putative variables of intraoperative opioid utilization were collected from 10 institutions. Log parenteral morphine equivalents (PME) was modeled in a multivariable linear regression model as a function of 15 covariates: 3 continuous covariates (age, anesthesia duration, year) and 12 factor covariates (peripheral block, neuraxial block, general anesthesia, emergency status, race, sex, remifentanil infusion, major surgery, American Society of Anesthesiologists [ASA] physical status, non-opioid analgesic count, Multicenter Perioperative Outcomes Group [MPOG] institution, surgery category). One interaction (year by MPOG institution) was included in the model. The regression model adjusted simultaneously for all included variables. Comparison of levels within a factor were reported as a ratio of medians with 95% credible intervals (CrI). RESULTS: A total of 1,104,324 cases between January 2012 and December 2016 were analyzed. The median (interquartile range) PME and standardized by weight PME per case for the study period were 15 (10-28) mg and 200 (111-347) µg/kg, respectively. As estimated in the multivariable model, there was a sustained decrease in opioid use (mean, 95% CrI) dropping from 152 (151-153) µg/kg in 2012 to 129 (129-130) µg/kg in 2016. The percent of variability in PME due to institution was 25.6% (24.8%-26.5%). Less opioids were prescribed in men (130 [129-130] µg/kg) than women (144 [143-145] µg/kg). The men to women PME ratio was 0.90 (0.89-0.90). There was substantial variability in PME administration among institutions, with the lowest being 80 (79-81) µg/kg and the highest being 186 (184-187) µg/kg; this is a PME ratio of 0.43 (0.42-0.43). CONCLUSIONS: We observed a reduction in intraoperative opioid administration over time, with variability in dose ranging between sexes and by procedure type. Furthermore, there was substantial variability in opioid use between institutions even when adjusting for multiple variables.

A Lower Tidal Volume Regimen during One-lung Ventilation for Lung Resection Surgery Is Not Associated with Reduced Postoperative Pulmonary Complications.

BACKGROUND: Protective ventilation may improve outcomes after major surgery. However, in the context of one-lung ventilation, such a strategy is incompletely defined. The authors hypothesized that a putative one-lung protective ventilation regimen would be independently associated with decreased odds of pulmonary complications after thoracic surgery. METHODS: The authors merged Society of Thoracic Surgeons Database and Multicenter Perioperative Outcomes Group intraoperative data for lung resection procedures using one-lung ventilation across five institutions from 2012 to 2016. They defined one-lung protective ventilation as the combination of both median tidal volume 5 ml/kg or lower predicted body weight and positive end-expiratory pressure 5 cm H2O or greater. The primary outcome was a composite of 30-day major postoperative pulmonary complications. RESULTS: A total of 3,232 cases were available for analysis. Tidal volumes decreased modestly during the study period (6.7 to 6.0 ml/kg; P < 0.001), and positive end-expiratory pressure increased from 4 to 5 cm H2O (P < 0.001). Despite increasing adoption of a "protective ventilation" strategy (5.7% in 2012 vs. 17.9% in 2016), the prevalence of pulmonary complications did not change significantly (11.4 to 15.7%; P = 0.147). In a propensity score matched cohort (381 matched pairs), protective ventilation (mean tidal volume 6.4 vs. 4.4 ml/kg) was not associated with a reduction in pulmonary complications (adjusted odds ratio, 0.86; 95% CI, 0.56 to 1.32). In an unmatched cohort, the authors were unable to define a specific alternative combination of positive end-expiratory pressure and tidal volume that was associated with decreased risk of pulmonary complications. CONCLUSIONS: In this multicenter retrospective observational analysis of patients undergoing one-lung ventilation during thoracic surgery, the authors did not detect an independent association between a low tidal volume lung-protective ventilation regimen and a composite of postoperative pulmonary complications.

Improving hand hygiene measures in low-resourced intensive care units: experience at the Kigali University Teaching Hospital in Rwanda.

Background: Proper hand hygiene (HH) practices have been shown to reduce healthcare-acquired infections. Several potential challenges in low-income countries might limit the feasibility of effective HH, including preexisting knowledge gaps and staffing. Aim: We sought to evaluate the feasibility of the implementation of effective HH practice at a teaching hospital in Rwanda. Methods: We conducted a prospective quality improvement project in the intensive care unit (ICU) at the Kigali University Teaching Hospital. We collected data before and after an intervention focused on HH adherence as defined by the World Health Organization '5 Moments for Hand Hygiene' and assuring availability of HH supplies. Pre-intervention data were collected throughout July 2019, and HH measures were implemented in August 2019. Post-implementation data were collected following a 3-month wash-in. Results: In total, 902 HH observations were performed to assess pre-intervention adherence and 903 observations post-intervention adherence. Overall, HH adherence increased from 25% (222 of 902 moments) before intervention to 75% (677 of 903 moments) after intervention (P < 0.001). Improvement was seen among all health professionals (nurses: 19-74%, residents: 23-74%, consultants: 29-76%). Conclusions: Effective HH measures are feasible in an ICU in a low-income country. Ensuring availability of supplies and training appears key to effective HH practices.

An Observational Study of the Pharmacokinetics of Surgeon-Performed Intercostal Nerve Blockade With Liposomal Bupivacaine for Posterior-Lateral Thoracotomy Analgesia.

BACKGROUND: Intercostal nerve blocks with liposomal bupivacaine are commonly used for thoracic surgery pain management. However, dose scheduling is difficult because the pharmacokinetics of a single-dose intercostal injection of liposomal bupivacaine has never been investigated. The primary aim of this study was to assess the median time to peak plasma concentration (Tmax) following a surgeon-administered, single-dose infiltration of 266 mg of liposomal bupivacaine as a posterior multilevel intercostal nerve block in patients undergoing posterolateral thoracotomy. METHODS: We chose a sample size of 15 adults for this prospective observational study. Intercostal injection of liposomal bupivacaine was considered time 0. Serum samples were taken at the following times: 5, 15, and 30 minutes, and 1, 2, 4, 8, 12, 24, 48, 72, and 96 hours. The presence of sensory blockade, rescue pain medication, and pain level were recorded after the patient was able to answer questions. RESULTS: Forty patients were screened, and 15 patients were enrolled in the study. Median (interquartile range [IQR]) Tmax was 24 (12) hours (confidence interval [CI], 19.5-28.5 hours) with a range of 15 minutes to 48 hours. The median (IQR) peak plasma concentration (Cmax) was 0.6 (0.3) µg/mL (CI, 00.45-0.74 µg/mL) in a range of 0.3-1.2. The serum bupivacaine concentration was undetectable (<0.2 µg/mL) at 96 hours in all patients. There was significant variability in reported pain scores and rescue opioid medication across the 15 patients. More than 50% of patients had return of normal chest wall sensation at 48 hours. All patients had resolution of nerve blockade at 96 hours. No patients developed local anesthetic toxicity. CONCLUSIONS: This study of the pharmacokinetics of liposomal bupivacaine following multilevel intercostal nerve blockade demonstrates significant variability and delay in systemic absorption of the drug. Peak serum concentration occurred at 48 hours or sooner in all patients. The serum bupivacaine concentration always remained well below the described toxicity threshold (2 µg/mL) during the 96-hour study period.

Multicenter Perioperative Outcomes Group Enhanced Observation Study Postoperative Pain Profiles, Analgesic Use, and Transition to Chronic Pain and Excessive and Prolonged Opioid Use Patterns Methodology.

To study the impact of anesthesia opioid-related outcomes and acute and chronic postsurgical pain, we organized a multicenter study that comprehensively combined detailed perioperative data elements from multiple institutions. By combining pre- and postoperative patient-reported outcomes with automatically extracted high-resolution intraoperative data obtained through the Multicenter Perioperative Outcomes Group (MPOG), the authors sought to describe the impact of patient characteristics, preoperative psychological factors, surgical procedure, anesthetic course, postoperative pain management, and postdischarge pain management on postdischarge pain profiles and opioid consumption patterns. This study is unique in that it utilized multicenter prospective data collection using a digital case report form integrated with the MPOG framework and database. Therefore, the study serves as a model for future studies using this innovative method. Full results will be reported in future articles; the purpose of this article is to describe the methods of this study.

Postoperative Low-Dose Tranexamic Acid After Major Spine Surgery: A Matched Cohort Analysis.

OBJECTIVE: This was a retrospective, cohort study investigating the efficacy and safety of continuous low-dose postoperative tranexamic acid (PTXA) on drain output and transfusion requirements following adult spinal deformity surgery. METHODS: One hundred forty-seven patients undergoing posterior instrumented thoracolumbar fusion of ≥ 3 vertebral levels at a single institution who received low-dose PTXA infusion (0.5-1 mg/kg/hr) for 24 hours were compared to 292 control patients who did not receive PTXA. The cohorts were propensity matched based on age, sex, American Society of Anesthesiologist physical status classification, body mass index, number of surgical levels, revision surgery, operative duration, and total intraoperative TXA dose (n = 106 in each group). Primary outcome was 72-hour postoperative drain output. Secondary outcomes were number of allogeneic blood transfusions. RESULTS: There was no significant difference in postoperative drain output in the PTXA group compared to control (660 ± 420 mL vs. 710 ± 490 mL, p = 0.46). The PTXA group received significantly more crystalloid (6,100 ± 3,100 mL vs. 4,600 ± 2,400 mL, p < 0.001) and red blood cell transfusions postoperatively (median [interquartile range]: 1 [0-2] units vs. 0 [0-1] units; incidence rate ratio [95% confidence interval], 1.6 [1.2-2.2]; p = 0.001). Rates of adverse events were comparable between groups. CONCLUSION: Continuous low-dose PTXA infusion was not associated with reduced drain output after spinal deformity surgery. No difference in thromboembolic incidence was observed. A prospective dose escalation study is warranted to investigate the efficacy of higher dose PTXA.

Individualized Quality Data Feedback Improves Anesthesiology Residents' Documentation of Depth of Neuromuscular Blockade Before Extubation.

Reversal of neuromuscular blockade is an important anesthesia quality measure, and anesthesiologists should strive to improve both documentation and practice of this measure. We hypothesized that the use of an electronic quality database to give individualized resident anesthesiologist feedback would increase the percentage of cases that residents successfully documented quantitative depth of neuromuscular blockade before extubation. The mean baseline success rate among anesthesiology residents was 80% (95% confidence interval [CI], 78-81) and increased by 14% (95% CI, 11-17; P < .001) after the residents were given their individualized quality data. Practice patterns improved quickly but were not sustained over 6 months.

Ventilator Mode Does Not Influence Blood Loss or Transfusion Requirements During Major Spine Surgery: A Retrospective Study.

BACKGROUND: Blood loss during adult spinal deformity surgery is multifactorial. Anesthetic-related factors, such as mode of mechanical ventilation, may contribute to intraoperative blood loss. The aim of this study was to determine the influence of ventilator mode and ventilator parameters on intraoperative blood loss and transfusion requirements in patients undergoing prone position spine surgery. METHODS: This single-center retrospective study examined electronic medical records of patients ≥18 years of age who underwent elective prone position spine surgery between May 2015 and June 2016. Associations between ventilator mode and ventilator parameters with intraoperative estimated blood loss (EBL), packed red blood cells (PRBCs), fresh-frozen plasma (FFP), cryoprecipitate and platelet transfusions, and subfascial drain output were examined using multiple linear regression models controlling for age, sex, American Society of Anesthesiologist (ASA) physical status score, body mass index (BMI), preoperative blood coagulation parameters and laboratory values, operative levels, cage constructs, osteotomies, transforaminal lumbar interbody fusions, laminectomies, reoperation, spine surgery invasiveness index, and operative time. In a secondary analysis, EBL, blood product transfusions, and postoperative drain output were compared between pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) propensity score-matched cohorts. RESULTS: Nine hundred forty-six records were reviewed, and 822 were included in the analysis. After adjusting for confounding, no statistically significant associations were observed between mode of ventilation and intraoperative EBL (estimate, -2; 95% confidence interval [CI], -248 to 245; P = .99) or blood product transfusions (PRBC: estimate, -9; 95% CI, -154 to 135; P = .90; FFP: estimate, -3; 95% CI, -59 to 54; P = .93; cryoprecipitate: estimate, -14; 95% CI, -70 to 43; P = .63; platelets: -7; 95% CI, -39 to 24; P = .64). After propensity score matching (n = 27 per group), no significant differences were observed in EBL (mean difference, 525 mL; 95% CI, -15 to 1065; P = .056) or blood transfusions (PRBC: mean difference, 208 mL; 95% CI, -23 to 439; P = .077; FFP (mean difference, 34 mL; 95% CI, -17 to 84; P = .19); cryoprecipitate (mean difference, 55 mL; 95% CI, -24 to 133; P = .17); or platelets (mean difference, 26 mL; 95% CI, -12 to 64; P = .18) between PCV and VCV groups. CONCLUSIONS: In prone position spine surgery, neither mode of mechanical ventilation nor airway pressure is associated with intraoperative blood loss or need for allogeneic transfusion. Use of modern ventilation strategies using lung protective techniques may mitigate differences in blood loss previously observed between PCV and VCV modes.

Preoperative Risk and the Association between Hypotension and Postoperative Acute Kidney Injury.

BACKGROUND: Despite the significant healthcare impact of acute kidney injury, little is known regarding prevention. Single-center data have implicated hypotension in developing postoperative acute kidney injury. The generalizability of this finding and the interaction between hypotension and baseline patient disease burden remain unknown. The authors sought to determine whether the association between intraoperative hypotension and acute kidney injury varies by preoperative risk. METHODS: Major noncardiac surgical procedures performed on adult patients across eight hospitals between 2008 and 2015 were reviewed. Derivation and validation cohorts were used, and cases were stratified into preoperative risk quartiles based upon comorbidities and surgical procedure. After preoperative risk stratification, associations between intraoperative hypotension and acute kidney injury were analyzed. Hypotension was defined as the lowest mean arterial pressure range achieved for more than 10 min; ranges were defined as absolute (mmHg) or relative (percentage of decrease from baseline). RESULTS: Among 138,021 cases reviewed, 12,431 (9.0%) developed postoperative acute kidney injury. Major risk factors included anemia, estimated glomerular filtration rate, surgery type, American Society of Anesthesiologists Physical Status, and expected anesthesia duration. Using such factors and others for risk stratification, patients with low baseline risk demonstrated no associations between intraoperative hypotension and acute kidney injury. Patients with medium risk demonstrated associations between severe-range intraoperative hypotension (mean arterial pressure less than 50 mmHg) and acute kidney injury (adjusted odds ratio, 2.62; 95% CI, 1.65 to 4.16 in validation cohort). In patients with the highest risk, mild hypotension ranges (mean arterial pressure 55 to 59 mmHg) were associated with acute kidney injury (adjusted odds ratio, 1.34; 95% CI, 1.16 to 1.56). Compared with absolute hypotension, relative hypotension demonstrated weak associations with acute kidney injury not replicable in the validation cohort. CONCLUSIONS: Adult patients undergoing noncardiac surgery demonstrate varying associations with distinct levels of hypotension when stratified by preoperative risk factors. Specific levels of absolute hypotension, but not relative hypotension, are an important independent risk factor for acute kidney injury.