Outcomes in perioperative care

Machine Learning Prediction Models for Postoperative Stroke in Elderly Patients: Analyses of the MIMIC Database

Objective

With the aging of populations and the high prevalence of stroke, postoperative stroke has become a growing concern. This study aimed to establish a prediction model and assess the risk factors for stroke in elderly patients during the postoperative period.

Methods

ML (Machine learning) prediction models were applied to elderly patients from the MIMIC (Medical Information Mart for Intensive Care)-III and MIMIC-VI databases. The SMOTENC (synthetic minority oversampling technique for nominal and continuous data) balancing technique and iterative SVD (Singular Value Decomposition) data imputation method were used to address the problem of category imbalance and missing values, respectively. We analyzed the possible predictive factors of stroke in elderly patients using seven modeling approaches to train the model. The diagnostic value of the model derived from machine learning was evaluated by the ROC curve (receiver operating characteristic curve).

Results

We analyzed 7,128 and 661 patients from MIMIC-VI and MIMIC-III, respectively. The XGB (extreme gradient boosting) model got the highest AUC (area under the curve) of 0.78 (0.75–0.81), making it better than the other six models, Besides, we found that XGB model with databalancing was better than that without data balancing. Based on this prediction model, we found hypertension, cancer, congestive heart failure, chronic pulmonary disease and peripheral vascular disease were the top five predictors. Furthermore, we demonstrated that hypertension predicted postoperative stroke is much more valuable.

Conclusion

Stroke in elderly patients during the postoperative period can be reliably predicted. We proved XGB model is a reliable predictive model, and the history of hypertension should be weighted more heavily than the results of laboratory tests to prevent postoperative stroke in elderly patients regardless of gender.

Influence of esmolol on requirement of inhalational agent using entropy and assessment of its effect on immediate postoperative pain score

Background and Context:

Beta-blockers have been used for attenuation of stress response, decreasing anaesthetic requirement and augmentation of the effect of opioids during general anaesthesia.

Aims and Objectives:

The present study aims to evaluate the influence of esmolol on the requirement of an inhalational agent while monitoring the depth of anaesthesia by entropy and also its effect on immediate postoperative pain score.

Methods:

Fifty American Society of Anaesthesiologists (ASA) I and II patients, between 25 and 65 years of age who underwent lower abdominal surgeries were randomly allocated to two groups: Group E and Group S of 25 patients each. Group E received esmolol infusion while Group S received the same volume of saline infusion. Demographic data, haemodynamics, amount of isoflurane used, end-tidal isoflurane concentration, postoperative pain score and total dose of morphine consumed in immediate postoperative period of 30 min were analyzed by using appropriate statistical tests. Value of P<0.05 was considered significant and P<0.001 as highly significant.

Results:

The two groups were comparable with respect to age, weight, ASA physical status, duration of surgery and amount of isoflurane used during anaesthesia. Assessment of postoperative pain was assessed by Visual Analogue Scale (VAS) which showed significant difference at 30 min. The total dose of morphine consumption was significantly less (P<0.05) in Group E for relief of postoperative pain.

Conclusions:

We conclude that in light of depth of anaesthesia monitor esmolol has no effect on requirement of isoflurane, but it decreases the postoperative pain as well as postoperative requirement of morphine without increasing the risk of awareness.

[Do anesthetic techniques influence postoperative outcomes? Part I]

The influence of anesthetic technique on postoperative outcomes has opened a wide field of research in recent years. High-risk patients undergoing non-cardiac surgery are those who have higher incidence of postoperative complications and mortality. A proper definition of this group of patients should focus maximal efforts and resources to improve the results. In view of the significant reduction in postoperative mortality and morbidity in last 20 years, perioperative research should take into account new indicators to investigate the role of anesthetic techniques on postoperative outcomes. Studies focused on the evaluation of intermediate outcomes would probably discriminate better effectiveness differences between anesthetic techniques. We review some of the major controversies arising in the literature about the impact of anesthetic techniques on postoperative outcomes. We have grouped the impact of these techniques into 9 major investigation areas: mortality, cardiovascular complications, respiratory complications, postoperative cognitive dysfunction, chronic postoperative pain, cancer recurrence, postoperative nausea/vomiting, surgical outcomes and resources utilization. In this first part of the review, we discuss the basis on postoperative outcomes research, mortality, cardiovascular and respiratory complications.

[Do anesthetic techniques influence postoperative outcomes? Part II]

The knowledge of the influence of anesthetic techniques in postoperative outcomes has opened a large field of research in recent years. In this second part, we review some of the major controversies arising from the literature on the impact of anesthetic techniques on postoperative outcomes in 6 areas: postoperative cognitive dysfunction, chronic postoperative pain, cancer recurrence, postoperative nausea/vomiting, surgical outcomes, and resources utilization. The development of protective and preventive anesthetic strategies against short and long-term postoperative complications will probably occupy an important role in our daily anesthetic practice. Dynamic postoperative pain control has been confirmed as one of the basic requirements of accelerated postoperative recovery programs ("fast-track surgery"), and it is also a preventive factor for development of chronic postoperative pain. The weight of anesthetic technique on postoperative immunosuppression is to be defined. The potential influence of anesthesia on cancer recurrence, is a highly controversial area of research. The classic pattern of perioperative fluid therapy may increase postoperative complications. On the other hand, the maintenance of normoglycemia and normothermia was associated with a decreased postoperative morbidity. The high volume of surgical procedures means that the adequacy of human, organizational and technological resources have a major impact on overall costs.