Mode of blood pressure monitoring and morbidity after noncardiac surgery: A prospective multicentre observational cohort study

Arterial cannulation with ultrasound: clinical trial protocol for a randomised controlled trial comparing handheld ultrasound versus palpation technique for radial artery cannulation

Background

Early intraoperative hypotension is associated with acute kidney and myocardial injury in patients undergoing noncardiac surgery. Precise arterial blood pressure measurement before and during the induction of general anaesthesia may avert early intraoperative hypotension. However, rapid arterial cannulation in anxious, conscious patients can be challenging. We describe the protocol for a randomised controlled trial designed to test the hypothesis that readily available, handheld ultrasound-guided arterial cannulation is the optimal method in conscious patients undergoing noncardiac surgery.

Methods

Participants >45 yr undergoing noncardiac surgery expected to last >120 min and requiring an overnight hospital stay will be eligible. We will randomly allocate participants to undergo cannulation of the radial artery in the non-dominant arm before the induction of general or regional anaesthesia using either handheld ultrasound-guided dynamic needle position technique or palpation. The primary outcome is first-pass successful arterial cannulation, analysed by intention-to-treat. Secondary outcomes include adequacy/characteristics of the arterial waveform and complications within 24 h of cannulation. We will require 118 patients to demonstrate a doubling of successful first-pass arterial cannulation, from ∼30% using the palpation approach (α=0.05; 1-β=0.1).

Results

This study has been approved by the NHS Health Research Authority and Health Care Research Wales (21/WA/0403) and commenced recruitment in May 2022.

Conclusions

This study will establish whether handheld ultrasound-guided arterial cannulation before the induction of anaesthesia should be the standard of care in patients at risk of developing perioperative organ injury after noncardiac surgery.

Clinical trial registration

NCT05249036.

Long-term mortality following complications after elective surgery: a secondary analysis of pooled data from two prospective cohort studies

BACKGROUND

Complications after surgery affect survival and quality of life. We aimed to confirm the relationship between postoperative complications and death within 1 yr after surgery.

METHODS

We conducted a secondary analysis of pooled data from two prospective cohort studies of patients undergoing surgery in five high-income countries between 2012 and 2014. Exposure was any complication within 30 days after surgery. Primary outcome was death within 1 yr after surgery, ascertained by direct follow-up or linkage to national registers. We adjusted for clinically important covariates using a mixed-effect multivariable Cox proportional hazards regression model. We conducted a planned subgroup analysis by type of complication. Data are presented as mean with standard deviation (sd), n (%), and adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs).

RESULTS

The pooled cohort included 10 132 patients. After excluding 399 (3.9%) patients with missing data or incomplete follow-up, 9733 patients were analysed. The mean age was 59 [sd 16.8] yr, and 5362 (55.1%) were female. Of 9733 patients, 1841 (18.9%) had complications within 30 days after surgery, and 319 (3.3%) died within 1 yr after surgery. Of 1841 patients with complications, 138 (7.5%) died within 1 yr after surgery compared with 181 (2.3%) of 7892 patients without complications (aHR 1.94 [95% CI: 1.53-2.46]). Respiratory failure was associated with the highest risk of death, resulting in six deaths amongst 28 patients (21.4%).

CONCLUSIONS

Postoperative complications are associated with increased mortality at 1 yr. Further research is needed to identify patients at risk of complications and to reduce mortality.

Hypotension as a marker or mediator of perioperative organ injury: a narrative review

Perioperative hypotension has been repeatedly associated with organ injury and worse outcome, yet many interventions to reduce morbidity by attempting to avoid or reverse hypotension have floundered. In part, this reflects uncertainty as to what threshold of hypotension is relevant in the perioperative setting. Shifting population-based definitions for hypertension, plus uncertainty regarding individualised norms before surgery, both present major challenges in constructing useful clinical guidelines that may help improve clinical outcomes. Aside from these major pragmatic challenges, a wealth of biological mechanisms that underpin the development of higher blood pressure, particularly with increasing age, suggest that hypotension (however defined) or lower blood pressure per se does not account solely for developing organ injury after major surgery. The mosaic theory of hypertension, first proposed more than 60 yr ago, incorporates multiple, complementary mechanistic pathways through which clinical (macrovascular) attempts to minimise perioperative organ injury may unintentionally subvert protective or adaptive pathways that are fundamental in shaping the integrative host response to injury and inflammation. Consideration of the mosaic framework is critical for a more complete understanding of the perioperative response to acute sterile and infectious inflammation. The largely arbitrary treatment of perioperative blood pressure remains rudimentary in the context of multiple complex adaptive hypertensive endotypes, defined by distinct functional or pathobiological mechanisms, including the regulation of reactive oxygen species, autonomic dysfunction, and inflammation. Developing coherent strategies for the management of perioperative hypotension requires smarter, mechanistically solid interventions delivered by RCTs where observer bias is minimised.