Utility of preoperative troponin I to predict mortality in adult liver transplant recipients: Revisiting pretransplant cardiac risk in the current MELD-allocation era

BACKGROUND

Preoperative risk assessment in liver transplant (LT) candidates, particularly related to cardiac risk, is an area of intense interest for transplant clinicians. Various cardiac testing methods are employed by transplant centers to characterize cardiac risk. Serum troponin is an established method for the detection of myocardial injury in a wide variety of clinical settings. Preoperative troponin screening has been reported to predict postoperative cardiac events and mortality in various surgical patient populations, however, the utility of preoperative troponin to predict posttransplant outcomes in current LT candidate populations requires further investigation.

METHODS

We performed a prospective blinded study in a cohort of 275 consecutive LT recipients at a single transplant center to determine if preoperative serum troponin I (TnI) was predictive for postoperative 1-year mortality.

RESULTS

Abnormal preoperative TnI levels (>.1 ng/mL) were found in 38 patients (14%). One-year mortality occurred in 19 patients (7%). There was no significant difference in mortality between patients with normal and abnormal troponin levels. Additionally, we found that there was no significant difference in early postoperative major adverse cardiac events between patient groups.

CONCLUSIONS

Contrary to previous reports, elevated preoperative TnI was not significantly predictive of posttransplant mortality in LT recipients at our institution.

Training and Validation of Deep Neural Networks for the Prediction of 90-Day Post-Liver Transplant Mortality Using UNOS Registry Data

Prediction models of post-liver transplant mortality are crucial so that donor organs are not allocated to recipients with unreasonably high probabilities of mortality. Machine learning algorithms, particularly deep neural networks (DNNs), can often achieve higher predictive performance than conventional models. In this study, we trained a DNN to predict 90-day post-transplant mortality using preoperative variables and compared the performance to that of the Survival Outcomes Following Liver Transplantation (SOFT) and Balance of Risk (BAR) scores, using United Network of Organ Sharing data on adult patients who received a deceased donor liver transplant between 2005 and 2015 (n = 57,544). The DNN was trained using 202 features, and the best DNN's architecture consisted of 5 hidden layers with 110 neurons each. The area under the receiver operating characteristics curve (AUC) of the best DNN model was 0.703 (95% CI: 0.682-0.726) as compared to 0.655 (95% CI: 0.633-0.678) and 0.688 (95% CI: 0.667-0.711) for the BAR score and SOFT score, respectively. In conclusion, despite the complexity of DNN, it did not achieve a significantly higher discriminative performance than the SOFT score. Future risk models will likely benefit from the inclusion of other data sources, including high-resolution clinical features for which DNNs are particularly apt to outperform conventional statistical methods.

A novel factor influencing perioperative midazolam administration: The effect of presentation dose on administration dose

Background and Aims:

Determinants of pharmaceutical unit presentations are not well understood and often appear indiscriminate. However, the dose administered may play a key role in the patient's anesthetic course. A recent change in a pharmaceutical vendor at our institution resulted in a change in midazolam presentation. In this study, we sought to determine whether the dose in which midazolam was dispensed to anesthesiologists was associated with the quantity of midazolam administered perioperatively.

Material and Methods:

In this retrospective, observational study, we examined 310 adult patients who underwent general anesthesia at a single site, tertiary care, university hospital before and after a change in midazolam presentation from 2 mg to 3 mg. The primary outcome was the quantity of midazolam administered during the anesthetic. Additional clinical variables measured included patient age, weight, gender, and American Society of Anesthesiology (ASA) classification.

Results:

The mean dose of midazolam administered to the 3 mg presentation cohort was 2.67 mg compared to 1.99 mg to the 2 mg presentation cohort (mean difference: 0.68 mg, 95% CI: 0.46–0.9 mg; P value <0.001). According to a logistic regression model, the odds of receiving a dose of 3 mg or greater in the 3 mg presentation cohort was 22 times greater than the odds of receiving such a dose in the 2 mg presentation cohort (OR: 22.3; 95% CI: 10.6–47.0; P < 0.001). This effect of presentation dose on administration dose was not observed in patients greater than or equal to 65 years of age.

Conclusions:

Midazolam presentation dose influences the administration dose.

The effect of kidney morcellation on operative time, incision complications, and postoperative analgesia after laparoscopic nephrectomy

INTRODUCTION

Compare the outcomes between kidney morcellation and two types of open specimen extraction incisions, several covariates need to be taken into consideration that have not yet been studied.

MATERIALS AND METHODS

We retrospectively reviewed 153 consecutive patients who underwent laparoscopic nephrectomy at our institution, 107 who underwent specimen morcellation and 46 with intact specimen removal, either those with connected port sites with a muscle-cutting incision and those with a remote, muscle-splitting incision. Operative time, postoperative analgesia requirements, and incisional complications were evaluated using univariate and multivariate analysis, comparing variables such as patient age, gender, body mass index (BMI), laterality, benign versus cancerous renal conditions, estimated blood loss, specimen weight, overall complications, and length of stay.

RESULTS

There was no significant difference for operative time between the 2 treatment groups (p = 0.65). Incision related complications occurred in 2 patients (4.4%) from the intact specimen group but none in the morcellation group (p = 0.03). Overall narcotic requirement was lower in patients with morcellated (41 mg) compared to intact specimen retrieval (66 mg) on univariate (p = 0.03) and multivariate analysis (p = 0.049). Upon further stratification, however, there was no significant difference in mean narcotic requirement between the morcellation and muscle-splitting incision subgroup (p = 0.14).

CONCLUSION

Morcellation does not extend operative time, and is associated with significantly less postoperative pain compared to intact specimen retrieval overall, although this is not statistically significant if a remote, muscle-splitting incision is made. Morcellation markedly reduces the risk of incisional-related complications.

Novel everting urologic access sheath: potential advantages of decreased cellular advancement

BACKGROUND AND PURPOSE

Axial forces are imposed on the urothelium during advancement of instruments across the urinary tract, potentially transferring cellular debris, bacteria, or urothelial carcinoma from one anatomic location to another. A prototype access sheath (Cystoglide; Percutaneous Systems, Mountain View, CA) was created that everts and radially dilates but does not provide axial forces during deployment that can be used in a variety of anatomic systems. We created a urinary-tract model to evaluate the in-vitro advancement of cells to compare this technology with using instruments alone.

MATERIALS AND METHODS

Blocks of sterile agar were created with 17F tracts of three lengths (2.7, 5.5, and 11 cm) with 5 mL of Luria-Bertani broth/ampicillin solution in a well at the end. The tips of a Cystoglide sheath and a traditional urologic instrument of the same diameter were dipped into a suspension of ampicillin-resistant Escherichia coli and advanced through the tracts. After a 10-second exposure, 4 mL of broth was collected and cultured. Bacterial growth was compared by measuring the optical density (OD) of the broth at multiple time points.

RESULTS

The mean overall OD of the broth was significantly lower (P < 0.001) in the novel-sheath cultures than with a traditional instrument for all advancements at all tract lengths.

CONCLUSION

The Cystoglide sheath significantly reduces the advancement of cells within an artificial urinary tract compared with a non-everting instrument. Clinical studies are needed to assess the utility of this technology in vivo.

Laparoscopic management of peripelvic renal cysts: University of California, San Francisco, experience and review of literature

OBJECTIVES

To report our experience and review published reports on the laparoscopic management of peripelvic renal cysts. Peripelvic renal cysts represent a unique subset of renal cysts, as they are rare, commonly symptomatic, and more difficult to treat than simple peripheral renal cysts. Minimally invasive methods for the treatment of peripelvic renal cysts, including laparoscopic decortication, have recently become more common.

METHODS

Four patients who presented with symptomatic peripelvic cysts underwent laparoscopic decortication at our institution. All four were men aged 47 to 65 years. One patient had undergone an unsuccessful prior cyst aspiration. All patients underwent preoperative computed tomography and retrograde pyelography. The mean number of peripelvic cysts per patient was 3.0, and the mean cyst size was 7.1 cm.

RESULTS

The mean operative time was 259 minutes (range 240 to 293), and the mean estimated blood loss was 30 mL (range 10 to 50). No evidence of cystic renal cell carcinoma was found on aspiration cytology or cyst wall pathologic examination. The mean hospital stay was 1.3 days. No inadvertent collecting system injuries and no intraoperative or postoperative complications occurred. All 4 patients achieved symptomatic relief and were determined to have radiologic success as determined by the 6-month postoperative computed tomography findings.

CONCLUSIONS

Laparoscopic ablation of peripelvic renal cysts is more difficult than that of simple peripheral renal cysts and demands a heightened awareness of potential complications and, therefore, more advanced surgical skills. In addition to our experience, a thorough review of published reports found this procedure to be safe and effective with appropriate patient selection.