Cardiovascular events in patients undergoing hip fracture surgery treated with remote ischaemic preconditioning: 1-year follow-up of a randomised clinical trial

Remote ischaemic preconditioning reduces the risk of myocardial injury within 4 days of hip fracture surgery. We aimed to investigate the effect of remote ischaemic preconditioning on the incidence of major adverse cardiovascular events 1 year after hip fracture surgery. We performed a phase-2, multicentre, randomised, observer-blinded, clinical trial between February 2015 and September 2017. We studied patients aged ≥ 45 years with a hip fracture and a minimum of one cardiovascular risk factor. Patients were allocated randomly to remote ischaemic preconditioning applied just before surgery or no treatment (control group). Remote ischaemic preconditioning was performed on the upper arm with a tourniquet in four cycles of 5 min ischaemia and 5 min reperfusion. Primary outcome was the occurrence of major adverse cardiovascular events within 1 year of surgery. A total of 316 patients were allocated randomly to the remote ischaemic preconditioning group and 309 patients to the control group. Major adverse cardiovascular events occurred in 43 patients (13.6%) in the remote ischaemic preconditioning group compared with 51 patients (16.5%) in the control group (adjusted hazard ratio (95%CI) 0.83 (0.55-1.25); p = 0.37). Fewer patients in the remote ischaemic preconditioning group had a myocardial infarction (11 (3.5%) vs. 22 (7.1%); hazard ratio (95%CI) 0.48 (CI 0.23-1.00); p = 0.04). Remote ischaemic preconditioning did not reduce the occurrence of major adverse cardiovascular events within 1 year of hip fracture surgery. The effect of remote ischaemic preconditioning on clinical cardiovascular outcomes in non-cardiac surgery needs confirmation in appropriately powered randomised clinical trials.

Adjusting Early Warning Score by clinical assessment: a study protocol for a Danish cluster-randomised, multicentre study of an Individual Early Warning Score (I-EWS)

INTRODUCTION

Track and trigger systems (TTSs) based on vital signs are implemented in hospitals worldwide to identify patients with clinical deterioration. TTSs may provide prognostic information but do not actively include clinical assessment, and their impact on severe adverse events remain uncertain. The demand for prospective, multicentre studies to demonstrate the effectiveness of TTSs has grown the last decade. Individual Early Warning Score (I-EWS) is a newly developed TTS with an aggregated score based on vital signs that can be adjusted according to the clinical assessment of the patient. The objective is to compare I-EWS with the existing National Early Warning Score (NEWS) algorithm regarding clinical outcomes and use of resources.

METHOD AND ANALYSIS

In a prospective, multicentre, cluster-randomised, crossover, non-inferiority study. Eight hospitals are randomised to use either NEWS in combination with the Capital Region of Denmark NEWS Override System (CROS) or implement I-EWS for 6.5 months, followed by a crossover. Based on their clinical assessment, the nursing staff can adjust the aggregated score with a maximum of -4 or +6 points. We expect to include 150 000 unique patients. The primary endpoint is all-cause mortality at 30 days. Coprimary endpoint is the average number of times per day a patient is NEWS/I-EWS-scored, and secondary outcomes are all-cause mortality at 48 hours and at 7 days as well as length of stay.

ETHICS AND DISSEMINATION

The study was presented for the Regional Ethics committee who decided that no formal approval was needed according to Danish law (J.no. 1701733). The I-EWS study is a large prospective, randomised multicentre study that investigates the effect of integrating a clinical assessment performed by the nursing staff in a TTS, in a head-to-head comparison with the internationally used NEWS with the opportunity to use CROS.

TRIAL REGISTRATION NUMBER

NCT03690128.

High intraoperative inspiratory oxygen fraction and risk of major respiratory complications

Background

High inspiratory oxygen fraction ( FIO2 ) may improve tissue oxygenation but also impair pulmonary function. We aimed to assess whether the use of high intraoperative FIO2 increases the risk of major respiratory complications.

Methods

We studied patients undergoing non-cardiothoracic surgery involving mechanical ventilation in this hospital-based registry study. The cases were divided into five groups based on the median FIO2 between intubation and extubation. The primary outcome was a composite of major respiratory complications (re-intubation, respiratory failure, pulmonary oedema, and pneumonia) developed within 7 days after surgery. Secondary outcomes included 30-day mortality. Several predefined covariates were included in a multivariate logistic regression model.

Results

The primary analysis included 73 922 cases, of whom 3035 (4.1%) developed a major respiratory complication within 7 days of surgery. For patients in the high- and low-oxygen groups, the median FIO2 was 0.79 [range 0.64-1.00] and 0.31 [0.16-0.34], respectively. Multivariate logistic regression analysis revealed that the median FIO2 was associated in a dose-dependent manner with increased risk of respiratory complications (adjusted odds ratio for high vs low FIO2 1.99, 95% confidence interval [1.72-2.31], P -value for trend <0.001). This finding was robust in a series of sensitivity analyses including adjustment for intraoperative oxygenation. High median FIO2 was also associated with 30-day mortality (odds ratio for high vs low FIO2 1.97, 95% confidence interval [1.30-2.99], P -value for trend <0.001).

Conclusions

In this analysis of administrative data on file, high intraoperative FIO2 was associated in a dose-dependent manner with major respiratory complications and with 30-day mortality. The effect remained stable in a sensitivity analysis controlled for oxygenation.

Clinical trial registration

NCT02399878.

[Review of Early Warning Score in preventing sudden critical illness and death]

Early Warning Score (EWS) are used extensively to identify patients at risk of deterioration during hospital admission. The validation of EWS has primarily focused on investigating predictive validity, i.e. the association between EWS and severe adverse events. Few studies have tested, whether EWS work in the clinical setting, and if it prevents severe adverse events from occurring. Many of these studies have methodological limitations, and their clinical relevance could be questioned. Currently, there is limited evidence to support, that the implementation of EWS reduces the occurrence of severe adverse events.

Perioperative hyperoxia and post-operative cardiac complications in adults undergoing non-cardiac surgery: Systematic review protocol

BACKGROUND

Oxygen therapy is used liberally for all patients undergoing anaesthesia. Recent studies have raised concerns that it may not be without complications when arterial oxygen concentrations reach supranormal concentrations (hyperoxia). Studies of oxygen therapy have raised concerns that the risk of myocardial injury and infarction is elevated in patients with hyperoxia due to vasoconstriction and formation of reactive oxygen species. Due to lack of symptoms or silent ischaemia, post-operative myocardial injury may be missed clinically. In some studies, perioperative hyperoxia has been linked to increased long-term mortality, but cardiac complications are sparsely evaluated. The aim of this review is to summarize current evidence to assess the risk and benefits of perioperative hyperoxia on post-operative cardiac complications.

METHODS

This systematic review will include meta-analyses and Trial Sequential Analyses. We will include randomized clinical trials with patients undergoing non-cardiac surgery if the allocation separates patients into a target of either higher (above 0.60) or lower (below 0.40) inspired oxygen fraction. To minimize the risk of systematic error, we will assess the risk of bias of the included trials using the Cochrane Risk of Bias Tool. The overall quality of evidence for each outcome will be assessed with the Grading of Recommendation, Assessment, Development and Evaluation (GRADE).

DISCUSSION

This systematic review will provide data on a severe, albeit rare, potential risk of oxygen therapy. We will do a trial sequential analysis to assess the robustness of results as well as help estimate the required patient size for future clinical trials.

Towards an automated multimodal clinical decision support system at the post anesthesia care unit

BACKGROUND

The aim of this study was to develop a predictive algorithm detecting early signs of deterioration (ESODs) in the post anesthesia care unit (PACU), thus being able to intervene earlier in the future to avoid serious adverse events. The algorithm must utilize continuously collected cardiopulmonary vital signs and may serve as an alternative to current practice, in which an alarm is activated by single parameters.

METHODS

The study was a single center, prospective cohort study including 178 patients admitted to the PACU after major surgical procedures. Peripheral blood oxygenation, arterial blood pressure, perfusion index, heart rate and respiratory rate were monitored continuously. Potential ESODs were automatically detected and scored by two independent experts with regards to the severity of the observation. Based on features extracted from the obtained measurements, a random forest classifier was trained, classifying each event being either an ESOD or not an ESOD. The algorithm was evaluated and compared to the automated single modality alarm system at the PACU.

RESULTS

The algorithm detected ESODs with an accuracy of 92.2% (99% CI: 89.6%-94.8%), sensitivity of 90.6% (99% CI: 85.7%-95.5%), specificity of 93.0% (99% CI: 89.9%-96.2%) and area under the receiver operating characteristic curve of 96.9% (99% CI: 95.3%-98.5%). The number of false alarms decreased by 85% (99% CI: 77%-93%) and the number of missed ESODs decreased by 73% (99% CI: 61%-85%) as compared to the currently used alarm system in the hospital. The algorithm was able to detect an ESOD in average 26.4 (99% CI: 1.1-51.7) minutes before the current single parameter system used in the PACU.

CONCLUSION

In conclusion, the proposed biomedical classification algorithm, when compared to the currently used single parameter alarm system of the hospital, showed significantly increased performance in both detecting ESODs fast and classifying these correctly. The clinical effect of the predictive system must be evaluated in future trials.

Technological aided assessment of the acutely ill patient - The case of postoperative complications

Surgical interventions come with complications and highly reported mortality after major surgery. The mortality may be a result of delayed detection of severe complications due to lower monitoring frequency in the general wards. Several studies have shown that continuous monitoring is superior to the manually intermittent recorded monitoring in terms of detecting abnormal physiological signs. Hopefully improved observations may result in earlier detection and clinical intervention. This narrative review will describe current monitoring possibilities for postoperative patients and how it may prevent complications. Several wireless systems are being developed for monitoring vital parameters, but many of these are not yet validated for critically ill patients. The ultimate goal with patient monitoring and detect of events is to prevent postoperative complications, death and costs in the health care system. A few studies indicate that monitoring systems detect deteriorating patients earlier than the nurses, and this was associated with less clinical instability. An important caveat of future devices is to assess their effect in relevant patient populations and not only in healthy test-subjects. Implementation of novel technologies is expensive although expected to be cost-effective if just few adverse events can be prevented. The future is here with promising devices and the possibility to give an unprecedented precise risk estimation of adverse post-surgical events. Next step is to integrate existing evidence based treatment algorithms to demonstrate the clinical efficacy of implementing the new technology.

[Practical management of troponin screening after non-cardiac surgery]

Myocardial injury after non-cardiac surgery (MINS) is associated with significant morbidity and mortality. Routine troponin screening is necessary to identify patients with MINS. Although some evidence indicates benefit with aspirin and statin therapy in these patients, a number of clinical considerations must be done in the practical management of MINS. This article describes current experience with identification and treatment in Denmark of patients with MINS.

Neuraxial block and postoperative epidural analgesia: effects on outcomes in the POISE-2 trial†

BACKGROUND

We assessed associations between intraoperative neuraxial block and postoperative epidural analgesia, and a composite primary outcome of death or non-fatal myocardial infarction, at 30 days post-randomization in POISE-2 Trial subjects.

METHODS

10 010 high-risk noncardiac surgical patients were randomized aspirin or placebo and clonidine or placebo. Neuraxial block was defined as intraoperative spinal anaesthesia, or thoracic or lumbar epidural anaesthesia. Postoperative epidural analgesia was defined as postoperative epidural local anaesthetic and/or opioid administration. We used logistic regression with weighting using estimated propensity scores.

RESULTS

Neuraxial block was not associated with the primary outcome [7.5% vs 6.5%; odds ratio (OR), 0.89; 95% CI (confidence interval), 0.73-1.08; P=0.24], death (1.0% vs 1.4%; OR, 0.84; 95% CI, 0.53-1.35; P=0.48), myocardial infarction (6.9% vs 5.5%; OR, 0.91; 95% CI, 0.74-1.12; P=0.36) or stroke (0.3% vs 0.4%; OR, 1.05; 95% CI, 0.44-2.49; P=0.91). Neuraxial block was associated with less clinically important hypotension (39% vs 46%; OR, 0.90; 95% CI, 0.81-1.00; P=0.04). Postoperative epidural analgesia was not associated with the primary outcome (11.8% vs 6.2%; OR, 1.48; 95% CI, 0.89-2.48; P=0.13), death (1.3% vs 0.8%; OR, 0.84; 95% CI, 0.35-1.99; P=0.68], myocardial infarction (11.0% vs 5.7%; OR, 1.53; 95% CI, 0.90-2.61; P=0.11], stroke (0.4% vs 0.4%; OR, 0.65; 95% CI, 0.18-2.32; P=0.50] or clinically important hypotension (63% vs 36%; OR, 1.40; 95% CI, 0.95-2.09; P=0.09).

CONCLUSIONS

Neuraxial block and postoperative epidural analgesia were not associated with adverse cardiovascular outcomes among POISE-2 subjects.

Depth of anaesthesia monitoring in obese patients: a randomized study of propofol-remifentanil

BACKGROUND

In obese patients, depth of anaesthesia monitoring could be useful in titrating intravenous anaesthetics. We hypothesized that depth of anaesthesia monitoring would reduce recovery time and use of anaesthetics in obese patients receiving propofol and remifentanil.

METHODS

We investigated 38 patients with a body mass index >or=30 kg/m(2) scheduled for an abdominal hysterectomy. Patients were randomized to either titration of propofol and remifentanil according to a cerebral state monitor (CSM group) or according to usual clinical criteria (control group). The primary end point was time to eye opening and this was assessed by a blinded observer.

RESULTS

Time to eye opening was 11.8 min in the CSM group vs. 13.4 min in the control group (P=0.58). The average infusion rate for propofol was a median of 516 vs. 617 mg/h (P=0.24) and for remifentanil 2393 vs. 2708 microg/h (P=0.04). During surgery, when the cerebral state index was continuously between 40 and 60, the corresponding optimal propofol infusion rate was 10 mg/kg/h based on ideal body weight.

CONCLUSION

No significant reduction in time to eye opening could be demonstrated when a CSM was used to titrate propofol and remifentanil in obese patients undergoing a hysterectomy. A significant reduction in remifentanil consumption was found.

Biphasic cardiac output changes during onset of spinal anaesthesia in elderly patients

BACKGROUND AND OBJECTIVE

In most studies of cardiac output changes after spinal anaesthesia, the time-resolution is limited. The aim of this study was to demonstrate cardiac output changes with high time-resolution during onset of spinal anaesthesia in elderly patients.

METHODS

We investigated 32 patients aged 60 yr scheduled for elective lower limb surgery. Fourteen received concurrent cardiovascular medication. Cardiac output was measured every 10 s using a pulse wave algorithm derived from the radial artery pressure curve, after calibration with lithium chloride (LiDCOplus). Data collection ended when the patients were ready for surgery, or if ephedrine was given to raise the mean arterial pressure.

RESULTS

Cardiac output increased initially reaching a maximum after a mean of 7 min. The average increase was 1.1 L min(-1) (P<0.0001). This occurred when mean arterial pressure was reduced 14 mmHg on average. At the end of data collection, cardiac output decreased 0.5 L min(-1) from baseline (P=0.02). Mean arterial pressure decreased progressively in all patients, and only minimal changes in heart rate were found.

CONCLUSIONS

Using this high time-resolution method, we detected biphasic changes in cardiac output during onset of spinal anaesthesia. Initially, cardiac output increased. Subsequently, it was significantly reduced from baseline, although this decrease was of minor clinical importance.