Innovating medical education: Development of an affordable, 3-D printed knot-tying simulator

BACKGROUND

Three-dimensional (3-D) printing offers an innovative option to produce clinical simulators because of its low production costs and widespread availability. We aimed to develop a low-cost, 3-D printed knot-tying simulator that overcomes the barriers students face in self-directed skills development.

APPROACH

Medical students completing a procedural residency preparation course (PRPC) completed a pre-survey with Likert scales and multiple choice questions to assess their perceptions of and barriers to self-directed knot-tying practice. Subsequently, a 3-D printed knot-tying simulator, which contains a progression of knot-tying challenges and a designated video curriculum, was designed. After utilising the simulator in a 1-hour, faculty-guided knot-tying session, PRPC students assessed the educational utility and usability of the simulator via a post-survey.

EVALUATION

The primary barriers students faced in engaging in self-directed knot-tying practice included limited accessibility to simulators and insufficient knowledge of knot-tying techniques. Many students (91.3%, n = 21) agreed that practicing with the simulator improved their knot-tying motor skills and was easy to use (100%, n = 23). Twenty-two (95.7%) students agreed that they would continue to use the simulator beyond the knot-tying session and PRPC.

IMPLICATIONS

We demonstrate the educational utility and usability of a novel 3-D printed knot-tying simulator for medical education. Enabling students to engage in self-directed technical skills development is critical in developing surgical skills that can translate to clinical environments. Our simulator highlights the benefits of 3-D printers as an innovative, inexpensive option to improve the availability and accessibility to medical education tools.

Comparative evaluation of transcutaneous oxygen tension vs ankle-brachial index as predictors of reoperation following below-knee amputation

OBJECTIVE

Decision-making regarding level of lower extremity amputation is sometimes challenging. Selecting an appropriate anatomic level for major amputation requires consideration of tradeoffs between postoperative function and risk of wound complications that may require additional operations, including debridement and/or conversion to above-knee amputation (AKA). We evaluated the utility of common, non-invasive diagnostic tests used in clinical practice to predict the need for reoperations among patients undergoing primary, elective below knee-amputations (BKAs) by vascular surgeons.

METHODS

Patients undergoing elective BKA over a 5-year period were identified using Current Procedural Terminology codes. Medical records were reviewed to characterize demographics, pre-amputation testing transcutaneous oxygen tension (TcPO2), and ankle-brachial index (ABI). The need for ipsilateral post-BKA reoperation (including BKA revision and/or conversion to AKA) regardless of indication was the primary outcome. Associations were evaluated using univariable and multivariable logistic regression models. Cutpoints for TcPO2 values associated with amputation reoperation were evaluated using receiver operating characteristic curves.

RESULTS

We identified 175 BKAs, of which 46 (26.3%) required ipsilateral reoperation (18.9% BKA revisions and 14.3% conversions to AKA). The mean age was 63.3 ± 14.8 years. Most patients were male (65.1%) and White (72.0%). Mean pre-amputation calf TcPO2 was 40.0 ± 20.5 mmHg, and mean ABI was 0.64 ± 0.45. In univariable models, post-BKA reoperation was associated with calf TcPO2 (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.94-0.99; P = .013) but not ABI (OR, 0.53; 95% CI, 0.19-1.46; P = .217). Univariable associations with reoperation were also identified for age (OR, 0.97; 95% CI, 0.94-0.990; P = .003) and diabetes (OR, 0.43; 95% CI, 0.21-0.87; P = .019). No associations with amputation revision were identified for gender, race, end-stage renal disease, or preoperative antibiotics. Calf TcPO2 remained associated with post-BKA reoperation in a multivariable model (OR, 0.97; 95% CI, 0.94-0.99; P = .022) adjusted for age (OR, 0.98; 95% CI, 0.94-1.01; P = .222) and diabetes (OR, 0.98; 95% CI, 0.94-1.01; P = .559). Receiver operating characteristic analysis suggested a TcPO2 ≥38 mmHg as an appropriate cut-point for assessing risk for BKA revision (area under the curve = 0.682; negative predictive value, 0.91).

CONCLUSIONS

Reoperation after BKA is common, and reoperation risk was associated with pre-amputation TcPO2. For patients undergoing elective BKA, higher risk of reoperation should be discussed with patients with an ipsilateral TcPO2 <38 mmHg.

Impact of cryoablation on operative outcomes in thoracotomy patients

OBJECTIVES

Cryoablation is increasingly being utilized as an alternative to epidurals for patients undergoing thoracotomies. Current evidence suggests cryoablation may decrease postoperative analgesia utilization, but could increase operative times. We hypothesized that the adoption of intraoperative cryoablation to manage post-thoracotomy pain would result in reduced length of stay and reduced perioperative analgesia compared to routine epidural use.

METHODS

A retrospective analysis was performed from a single, quaternary referral centre, prospective database on patients receiving thoracotomies between January 2020 and March 2022. Patients undergoing transthoracic hiatal hernia repair, lung resection or double-lung transplant were divided between epidural and cryoablation cohorts. Primary outcomes were length of stay, intraoperative procedure time, crossover pain management and oral narcotic usage the day before discharge.

RESULTS

During the study period, 186 patients underwent a transthoracic hiatal hernia repair, lung resection or double-lung transplant with 94 receiving a preoperative epidural and 92 undergoing cryoablation. Subgroup analysis demonstrated no significant differences in demographics, operative length, length of stay or perioperative narcotic use. Notably, over a third of patients in each cryoablation subgroup received a postoperative epidural (45.5% transthoracic hiatal hernia repair, 38.5% lung resection and 45.0% double-lung transplant) for further pain management during their admission.

CONCLUSIONS

Cryoablation use was not associated with an increase in procedure time, a decrease in narcotic use or length of stay. Surprisingly, many cryoablation patients received epidurals in the postoperative period for further pain control. Additional analysis is needed to fully understand the benefits and costs of epidural versus cryoablation strategies.

Non-high-density lipoprotein cholesterol and treatment targets in vascular surgery patients

INTRODUCTION

Low-density lipoprotein cholesterol (LDL) is a known contributing factor to atherosclerotic cardiovascular disease (ASCVD) and a primary therapeutic target for medical management of ASCVD. Non-high-density lipoprotein cholesterol (non-HDL) has recently been identified as a secondary therapeutic target but is not yet widely used in vascular surgery patients. We sought to assess if vascular surgery patients were undertreated per non-HDL therapeutic guidelines.

METHODS

This was an observational study that used a single-center database to identify a cohort of adult patients who received care from a vascular surgery provider from 01/2001 to 07/2021. ICD-9/10-CM codes were used to identify patients with a medical history of hyperlipidemia (HLD), coronary artery disease (CAD), cerebrovascular occlusive disease (CVOD), peripheral artery disease (PAD), hypertension (HTN), or diabetes mellitus (DM). Patient smoking status and medications were also identified. Lab values were obtained from the first and last patient encounter within our system. Primary outcomes were serum concentrations of LDL and non-HDL, with therapeutic thresholds defined as 70 mg/dL and 100 mg/dL, respectively.

RESULTS

The cohort included 2465 patients. At first encounter, average age was 59.3 years old, 21.4% were on statins, 8.4% were on a high-intensity statin, 25.7% were diagnosed with HLD, 5.2% with CAD, 15.3% with PAD, 26.3% with DM, 18.6% with HTN, and 2.1% with CVOD. At final encounter, mean age was 64.8 years, 23.5% were on statins with 10.1% on high-intensity statin. Diagnoses frequency did not change at final encounter. At first encounter, nearly two-thirds of patients were not at an LDL <70 mg/dL (62.3%) or non-HDL <100 mg/dL (66.0%) with improvement at final encounter to 45.2 and 40.5% of patients not at these LDL or non-HDL treatment thresholds, respectively. Patients on statins exhibited similar trends with 51.1 and 50.1% of patients not at LDL or non-HDL treatment thresholds at first encounter and 39.9 and 35.4% not at LDL or non-HDL treatment thresholds at last encounter. Importantly, 6.9% of patients were at LDL but not non-HDL treatment thresholds.

DISCUSSION

Among vascular surgery patients, over half did not meet non-HDL targets. These results suggest that we may be vastly under-performing adequate medical optimization with only about one-fourth of patients on a statin at their final encounter and approximately one-tenth of patients being treated with a high-intensity statin. With recent evidence supporting non-HDL as a valuable measurement for atherosclerotic risk, there is potential to optimize medical management beyond current high-intensity statin therapy. Further investigation is needed regarding the risk of adverse events between patients treated with these varied therapeutic targets.

Nodo-Tie: an innovative, 3-D printed simulator for surgical knot-tying skills development

Introduction

Clinical simulators are an important resource for medical students seeking to improve their fundamental surgical skills. Three-dimensional (3-D) printing offers an innovative method to create simulators due to its low production costs and reliable printing fidelity. We aimed to validate a 3-D printed knot-tying simulator named Nodo-Tie.

Methods

We designed a 3-D printed knot-tying simulator integrated with a series of knot-tying challenges and a designated video curriculum made accessible via a quick-response (QR) code. The Nodo-Tie, which costs less than $1 to print and assemble, was distributed to second-year medical students starting their surgical clerkship. Participants were asked to complete a survey gauging the simulator's usability and educational utility. The time between simulator distribution and survey completion was eight weeks.

Results

Students perceived the Nodo-Tie as easy-to-use (4.6 ± 0.8) and agreed it increased both their motor skills (4.5 ± 0.9) and confidence (4.5 ± 0.8) for tying surgical knots in the clinical setting. Many students agreed the Nodo-Tie provided a stable, durable surface for knot-tying practice (83.7%, n = 41) and that they would continue to use it beyond their participation in the study period (91.7%, n = 44).

Discussion

Medical students found this interactive, 3-D printed knot-tying simulator to be an effective tool to use for self-directed development of their knot-tying skills. Given the Nodo-Tie's low cost, students were able to keep the Nodo-Tie for use beyond the study period. This increases the opportunity for students to engage in the longitudinal practice necessary to master knot-tying as they progress through their medical education.

Key messages

Clinical simulators provide proactive learners with reliable, stress-free environments to engage in self-directed surgical skills development. The Nodo-Tie, a 3-D printed simulator, serves as a cost-effective, interactive tool for medical students to develop their knot-tying abilities beyond the clinical setting.

Superior mesenteric aneurysm associated with median arcuate ligament syndrome and a single celiacomesenteric trunk

Median arcuate ligament syndrome (MALS) is known to promote arterial collateral circulation development from mesenteric vessel compression and can lead to the development of visceral aneurysms. These aneurysms are often diagnosed at the time of rupture and pose a significant morality risk without appropriate intervention. A celiacomesenteric trunk is a rare anatomic variant in which the celiac artery and superior mesenteric artery share a common origin and has been postulated as a risk factor for developing MALS. In this report, we present a novel case of MALS in a patient with a celiacomesenteric trunk and a superior mesenteric artery aneurysm.