Candidate Kidney Protective Strategies for Patients Undergoing Major Abdominal Surgery: A Secondary Analysis of the RELIEF Trial Cohort.

BACKGROUND: Acute kidney injury (AKI) is common after major abdominal surgery. Selection of candidate kidney protective strategies for testing in large trials should be based on robust preliminary evidence. METHODS: A secondary analysis of the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery (RELIEF) trial was conducted in adult patients undergoing major abdominal surgery and randomly assigned to a restrictive or liberal perioperative fluid regimen. The primary outcome was maximum AKI stage before hospital discharge. Two multivariable ordinal regression models were developed to test the primary hypothesis that modifiable risk factors associated with increased maximum stage of postoperative AKI could be identified. Each model used a separate approach to variable selection to assess the sensitivity of the findings to modeling approach. For model 1, variable selection was informed by investigator opinion; for model 2, the Least Absolute Shrinkage and Selection Operator (LASSO) technique was used to develop a data-driven model from available variables. RESULTS: Of 2,444 patients analyzed, stage 1, 2, and 3 AKI occurred in 223 (9.1%), 59 (2.4%), and 36 (1.5%) patients, respectively. In multivariable modeling by model 1, administration of a nonsteroidal anti-inflammatory drug or cyclooxygenase-2 inhibitor, intraoperatively only (odds ratio, 1.77 [99% CI, 1.11 to 2.82]), and preoperative day-of-surgery administration of an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker compared to no regular use (odds ratio, 1.84 [99% CI, 1.15 to 2.94]) were associated with increased odds for greater maximum stage AKI. These results were unchanged in model 2, with the additional finding of an inverse association between nadir hemoglobin concentration on postoperative day 1 and greater maximum stage AKI. CONCLUSIONS: Avoiding intraoperative nonsteroidal anti-inflammatory drugs or cyclooxygenase-2 inhibitors is a potential strategy to mitigate the risk for postoperative AKI. The findings strengthen the rationale for a clinical trial comprehensively testing the risk-benefit ratio of these drugs in the perioperative period.

What and when to debrief: a scoping review examining interprofessional clinical debriefing.

INTRODUCTION: Clinical debriefing (CD) improves teamwork and patient care. It is implemented across a range of clinical contexts, but delivery and structure are variable. Furthermore, terminology to describe CD is also inconsistent and often ambiguous. This variability and the lack of clear terminology obstructs understanding and normalisation in practice. This review seeks to examine the contextual factors relating to different CD approaches with the aim to differentiate them to align with the needs of different clinical contexts. METHODS: Articles describing CD were extracted from Medline, CINAHL, ERIC, PubMed, PsychINFO and Academic Search Complete. Empirical studies describing CD that involved two or more professions were eligible for inclusion. Included papers were charted and analysed using the Who-What-When-Where-Why-How model to examine contextual factors which were then used to develop categories of CD. Factors relating to what prompted debriefing and when debriefing occurred were used to differentiate CD approaches. RESULTS: Forty-six papers were identified. CD was identified as either prompted or routine, and within these overarching categories debriefing was further differentiated by the timing of the debrief. Prompted CD was either immediate or delayed and routine CD was postoperative or end of shift. Some contextual factors were unique to each category while others were relatively heterogeneous. These categories help clarify the alignment between the context and the intention of CD. CONCLUSIONS: The proposed categories offer a practical way to examine and discuss CD which may inform decisions about implementation. By differentiating CD according to relevant contextual factors, these categories may reduce confusion which currently hinders discourse and implementation. The findings from this review promote context-specific language and a shift away from conceptions of CD that embody a one-size-fits-all approach.

Feasibility and acceptability of the use of flash glucose monitoring encountered by Indigenous Australians with type 2 diabetes mellitus: initial experiences from a pilot study.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is highly prevalent within the Indigenous Australian community. Novel glucose monitoring technology offers an accurate approach to glycaemic management, providing real-time information on glucose levels and trends. The acceptability and feasibilility of this technology in Indigenous Australians with T2DM has not been investigated. OBJECTIVE: This feasibility phenomenological study aims to understand the experiences of Indigenous Australians with T2DM using flash glucose monitoring (FGM). METHODS: Indigenous Australians with T2DM receiving injectable therapy (n = 8) who used FGM (Abbott Freestyle Libre) for 6-months, as part of a clinical trial, participated in semi-structured interviews. Thematic analysis of the interviews was performed using NVivo12 Plus qualitative data analysis software (QSR International). RESULTS: Six major themes emerged: 1) FGM was highly acceptable to the individual; 2) FGM's convenience was its biggest benefit; 3) data from FGM was a tool to modify lifestyle choices; 4) FGM needed to be complemented with health professional support; 5) FGM can be a tool to engage communities in diabetes management; and 6) cost of the device is a barrier to future use. CONCLUSIONS: Indigenous Australians with T2DM had positive experiences with FGM. This study highlights future steps to ensure likelihood of FGM is acceptable and effective within the wider Indigenous Australian community.

Translocator protein is a marker of activated microglia in rodent models but not human neurodegenerative diseases.

Microglial activation plays central roles in neuroinflammatory and neurodegenerative diseases. Positron emission tomography (PET) targeting 18 kDa Translocator Protein (TSPO) is widely used for localising inflammation in vivo, but its quantitative interpretation remains uncertain. We show that TSPO expression increases in activated microglia in mouse brain disease models but does not change in a non-human primate disease model or in common neurodegenerative and neuroinflammatory human diseases. We describe genetic divergence in the TSPO gene promoter, consistent with the hypothesis that the increase in TSPO expression in activated myeloid cells depends on the transcription factor AP1 and is unique to a subset of rodent species within the Muroidea superfamily. Finally, we identify LCP2 and TFEC as potential markers of microglial activation in humans. These data emphasise that TSPO expression in human myeloid cells is related to different phenomena than in mice, and that TSPO-PET signals in humans reflect the density of inflammatory cells rather than activation state.

Application of the theoretical framework of acceptability in a surgical setting: Theoretical and methodological insights.

PURPOSE: Methods for assessing acceptability of healthcare interventions have been inconsistent until the development of the theoretical framework of acceptability (TFA). Despite its rapid adoption in healthcare research, the TFA has rarely been used to assess acceptability of surgical interventions. We sought to explore the sufficiency of the TFA in this context and provide methodological guidance to support systematic use of this framework in research. METHOD: Acceptability was assessed in a consecutive sample of 15 patients at least 3 months post-joint replacement surgery via theory-informed semi-structured interviews. A detailed description of the application of the TFA is reported. This includes: development of the interview guide (including questions to assess theoretical sufficiency), analysis of interview data and interpretation of findings. RESULTS: Interview data were substantially codable into the TFA constructs but required the addition of a construct, labelled 'perceived safety and risk', and relabelling and redefining an existing construct (new label: 'opportunity costs and gains'). Methodological recommendations for theory-informed interview studies include producing interview support material to enhance precision of the intervention description, conducting background conversations with a range of stakeholders in the healthcare setting, and conducting first inductive and then deductive thematic analysis. CONCLUSION: The sufficiency of the TFA could be enhanced for use when assessing interventions with an identifiable risk profile, such as surgery, by the inclusion of an additional construct to capture perceptions of risk and safety. We offer these methodological recommendations to guide researchers and facilitate consistency in the application of the TFA in theory-informed interview studies.

Cell-autonomous immune dysfunction driven by disrupted autophagy in C9orf72-ALS iPSC-derived microglia contributes to neurodegeneration.

Although microglial activation is widely found in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), the underlying mechanism(s) are poorly understood. Here, using human-induced pluripotent stem cell-derived microglia-like cells (hiPSC-MG) harboring the most common ALS/FTD mutation (C9orf72, mC9-MG), gene-corrected isogenic controls (isoC9-MG), and C9orf72 knockout hiPSC-MG (C9KO-MG), we show that reduced C9ORF72 protein is associated with impaired phagocytosis and an exaggerated immune response upon stimulation with lipopolysaccharide. Analysis of the C9ORF72 interactome revealed that C9ORF72 interacts with regulators of autophagy and functional studies showed impaired initiation of autophagy in mC9-MG and C9KO-MG. Coculture studies with motor neurons (MNs) demonstrated that the autophagy deficit in mC9-MG drives increased vulnerability of mC9-MNs to excitotoxic stimulus. Pharmacological activation of autophagy ameliorated both cell-autonomous functional deficits in hiPSC-MG and MN death in MG-MN coculture. Together, these findings reveal an important role for C9ORF72 in regulating immune homeostasis and identify dysregulation in myeloid cells as a contributor to neurodegeneration in ALS/FTD.

Low tidal volume ventilation for patients undergoing laparoscopic surgery: a secondary analysis of a randomised clinical trial.

BACKGROUND: We recently reported the results for a large randomized controlled trial of low tidal volume ventilation (LTVV) versus conventional tidal volume (CTVV) during major surgery when positive end expiratory pressure (PEEP) was equal between groups. We found no difference in postoperative pulmonary complications (PPCs) in patients who received LTVV. However, in the subgroup of patients undergoing laparoscopic surgery, LTVV was associated with a numerically lower rate of PPCs after surgery. We aimed to further assess the relationship between LTVV versus CTVV during laparoscopic surgery. METHODS: We conducted a post-hoc analysis of this pre-specified subgroup. All patients received volume-controlled ventilation with an applied PEEP of 5 cmH2O and either LTVV (6 mL/kg predicted body weight [PBW]) or CTVV (10 mL/kg PBW). The primary outcome was the incidence of a composite of PPCs within seven days. RESULTS: Three hundred twenty-eight patients (27.2%) underwent laparoscopic surgeries, with 158 (48.2%) randomised to LTVV. Fifty two of 157 patients (33.1%) assigned to LTVV and 72 of 169 (42.6%) assigned to conventional tidal volume developed PPCs within 7 days (unadjusted absolute difference, - 9.48 [95% CI, - 19.86 to 1.05]; p = 0.076). After adjusting for pre-specified confounders, the LTVV group had a lower incidence of the primary outcome than patients receiving CTVV (adjusted absolute difference, - 10.36 [95% CI, - 20.52 to - 0.20]; p = 0.046). CONCLUSION: In this post-hoc analysis of a large, randomised trial of LTVV we found that during laparoscopic surgeries, LTVV was associated with a significantly reduced PPCs compared to CTVV when PEEP was applied equally between both groups. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry no: 12614000790640.

Taking More Society for Academic Emergency Medicine Practice Tests Does Not Lead to Improved National EM-M4 Exam Scores.

INTRODUCTION: Emergency medicine (EM) is a required clerkship for third-year medical students, and an elective EM acting internship (AI) is available to fourth-year students at our institution. The Society for Academic Emergency Medicine's (SAEM) National Emergency Medicine M4 Examination (EM-M4) is administered to students at the end of the EM AI experience. To prepare for the exam, students gain access to 23 practice tests available from SAEM. In this study we investigate the correlation between the number of practice tests taken and EM-M4 performance. METHODS: We collected data for EM-M4 and the US Medical Licensing Exam (USMLE) Step 2 Clinical Knowledge (CK) from students completing a MS4 EM clerkship in consecutive medical school classes from 2014-2017 at a private medical school. In addition, we collected data during the clerkship on the number of practice exams taken and whether a comprehensive practice exam was taken. We analyzed the study population three ways to determine whether the number of practice tests impacted final exam results: a binary distribution (1-11 or 12-23 tests taken); quaternary distribution (1-6, 7-12, 13-18, or 19-23 tests taken); and individual test variability (1,2,3,…22,23 tests taken). Complete data for 147 students was used for data analysis. RESULTS: The EM-M4 showed moderate (r = 0.49) correlations with USMLE Step 2 CK. There was no significant difference in EM-M4 performance in the binary analysis (P ≤ 0.09), the quaternary analysis (P ≤ 0.09), or the continuous variable analysis (P ≤ 0.52). Inclusion of a comprehensive practice test also did not correlate with EM-M4 performance (P ≤ 0.78). CONCLUSION: Degree of utilization of SAEM practice tests did not seem to correlate with performance on the EM-M4 examination at our institution. This could be due to many factors including that the question bank is composed of items that had poor item discrimination, possible inadequate coverage of EM curriculum, and/or use of alternative study methods. While further investigation is needed, if our conclusions prove generalizable, then using the SAEM practice tests is an extraneous cognitive load from a modality without proven benefit.

A protocol for a prospective, multicentre observational study to determine if nonanaemic iron deficiency worsens postoperative outcome in patients undergoing elective surgery for resection of colorectal cancer: The NATO study.

BACKGROUND: Preoperative absolute and functional iron deficiency anaemia is associated with poor postoperative outcomes in patients undergoing surgery for colorectal cancer. It is biologically plausible that "early", or "nonanaemic" iron deficiency may also be associated with worse postoperative outcomes in similar cohorts, albeit at lesser severity than that seen for anaemia. The evidence supporting this assertion is of low quality. METHODS: We have designed a prospective, observational study to delineate associations between preoperative non-anaemic iron deficiency and postoperative outcomes after surgery for colorectal cancer. Patients without anaemia, undergoing elective surgery for colorectal cancer will be allocated to an iron replete or an iron deficient group based on preoperative transferrin saturation. The primary outcome is days alive and at home on postoperative day 90. Secondary outcomes include days alive and at home on postoperative day 30, length of hospital stay, readmission to acute care, postoperative complications, health-related quality of life scores, quality of postoperative recovery, and requirement for allogeneic blood transfusion. The planned sample size is 422 patients, which has 80% power to detect a two-day difference in the primary outcome. The study commenced in May 2019. CONCLUSION: The results of this study will provide patients and clinicians with high-quality evidence concerning associations between nonanaemic iron deficiency and patient-centred outcomes after surgery for colorectal cancer. The study will be conducted in multiple urban and rural centres across Australia and New Zealand. The results will be highly generalisable to contemporary surgical practice and should be rapidly translated.

The epidemiology of rapid response team activation amongst patients undergoing major gastrointestinal surgery.

BACKGROUND: Clinical deterioration requiring rapid response team (RRT) review is associated with increased morbidity amongst hospitalised patients. The frequency of and association with RRT calls in patients undergoing major gastrointestinal surgery is unknown. Understanding the epidemiology of RRT calls might identify areas for quality improvement in this cohort. OBJECTIVES: The objective of this study is to identify perioperative risks and outcome associations with RRT review following major gastrointestinal surgery. METHODS: We conducted a retrospective cohort study using electronic databases at a large Australian university hospital. We included adult patients admitted for major gastrointestinal surgery between 1 January 2015 and 31 March 2018. RESULTS: Of 7158 patients, 514 (7.4%) required RRT activation postoperatively. After adjustment, variables associated with RRT activation included the following: hemiplegia/paraplegia (odds ratio [OR]: 8.0, 95% confidence interval [CI]: 2.3 to 27.8, p = 0.001), heart failure (OR: 6.9, 95% CI: 3.3 to 14.6, p < 0.001), peripheral vascular disease (OR: 5.3, 95% CI: 2.7 to 10.4, p < 0.001), peptic ulcer disease (OR: 4.2, 95% CI: 2.2 to 8.0, p < 0.001), chronic obstructive pulmonary disease (OR: 4.0, 95% CI: 2.2 to 7.2, p < 0.001), and emergency admission status (OR: 2.6, 95% CI: 2.1 to 3.3, p < 0.001). Following the index operation, 46% of first RRT activations occurred within 24 h of surgery and 61% had occurred within 48 h. The most common triggers for RRT activation were tachycardia, hypotension, and tachypnoea. Postoperative RRT activation was associated with in-hospital mortality (OR: 6.7, 95% CI: 3.8 to 11.8, p < 0.001), critical care admission (incidence rate ratio: 8.18, 95% CI: 5.23 to 12.77, p < 0.001), and longer median length of hospital stay (12 days vs. 2 days, p < 0.001) compared to no RRT activation. CONCLUSION: After major gastrointestinal surgery, one in 14 patients had an RRT activation, almost half within 24 h of surgery. Such activation was independently associated with increased morbidity and mortality. Identified associations may guide more pre-emptive management for those at an increased risk of RRT activation.

Exploring patient acceptability of a short-stay care pathway in hospital post arthroplasty: A theory-informed qualitative study.

INTRODUCTION: Arthroplasty is an effective, yet costly, surgical procedure for end-stage osteoarthritis. Shorter stays in hospital are being piloted in Australia. In some countries, short stay is established practice, associated with improving perioperative care and enhanced recovery after surgery practices. Exploring the acceptability to patients of a short stay care pathway in hospital postarthroplasty is important for informing health policy, adoption and potential scalability of this model of care. METHODS: Consecutive patients at one site, at least 3 months post total joint arthroplasty, were invited to participate in theory-informed semi-structured qualitative interviews. The Theoretical Framework of Acceptability (TFA) informed development of the interview guide. Interview data were analysed using the Framework Method. RESULTS: Eighteen patients were invited. Fifteen consented to be contacted and were interviewed. Short-stay post arthroplasty was highly acceptable to patients who had the supports necessary to recover safely at home. Key findings were as follows: flexibility of short-stay care pathway was essential and valued; prior beliefs and expectations informed acceptability; and the absence of out-of-pocket expenses had an incentivizing effect, but was not the primary reason for patients choosing this care pathway. Further themes analysed within the TFA constructs highlighted nuances of acceptability relating to this model of care. CONCLUSIONS: A short stay in hospital post arthroplasty appeared to be acceptable to patients who had experienced this care pathway. Our thematic findings identified aspects of the short-stay care pathway that enhanced acceptability and some aspects that limited acceptability. These findings can inform refinement of the short-stay care pathway. PATIENT OR PUBLIC CONTRIBUTION: Patients/people with lived experience were not involved in the study design or conduct of this preliminary work; as this short-stay model of care was recently introduced, only a small group of patients was eligible to participate in this study. This study is the first step towards understanding the experiences of patients about a short-stay model of care post arthroplasty. The findings will help inform future patient and public involvement in expanding the programme.

Postoperative anaemia and patient-centred outcomes after major abdominal surgery: a retrospective cohort study.

BACKGROUND: Compared with anaemia before surgery, the underlying pathogenesis and implications of postoperative anaemia are largely unknown. METHODS: This retrospective cohort study analysed prospective data obtained from 2983 adult patients across 47 centres enrolled in a clinical trial evaluating restrictive and liberal intravenous fluids. The primary endpoint was persistent disability or death up to 90 days after surgery. Secondary endpoints included major septic complications, hospital stay, and patient quality of recovery using a 15-item quality of recovery (QoR-15) score, hospital re-admissions, and disability-free survival up to 12 months after surgery. Anaemia and disability were defined according to the WHO definitions. Multivariable regression was used to adjust for baseline risk and surgery. RESULTS: A total of 2983 patients met inclusion criteria for this study, of which 78.5% (95% confidence interval [CI], 76.7-80.1%) had postoperative anaemia. Patients with postoperative anaemia had a higher adjusted risk of death or disability up to 90 days after surgery when compared with those without anaemia: 18.2% vs 9.2% (risk ratio [RR]=1.51; 95% CI, 1.10-2.07, P=0.011); lower QoR-15 scores on Day 3 and Day 30, 105 (95% CI, 87-119) vs 114 (95% CI, 99-128; P<0.001), and 130 (95% CI, 112-140) vs 139 (95% CI, 121-144; P<0.011), respectively; higher adjusted risk of a composite of mortality/septic complications, 2.01 (95% CI, 1.55-42.67; P<0.001); unplanned admission to ICU (RR=2.65; 95% CI, 1.65-4.23; P<0.001); and longer median (inter-quartile range [IQR]) hospital stays, 6.6 (4.4-12.4) vs 3.7 (2.5-6.5) days (P<0.001). CONCLUSIONS: Postoperative anaemia is common and is independently associated with poor outcomes after surgery. Optimal prevention and treatment strategies need to be investigated. CLINICAL TRIAL REGISTRATION: NCT04978285 (ClinicalTrials.gov).

Associations between non-anaemic iron deficiency and outcomes following elective cardiac surgery (IDOCS): a prospective cohort study.

BACKGROUND: One in two adults undergoing cardiac surgery are iron deficient, best practice guidelines and consensus statements recommend routine investigation and treatment of iron deficiency before elective cardiac surgery, even in the absence of anaemia; however, it is not clear if non-anaemic iron deficiency is associated with worse outcomes in this patient population. We hypothesised that iron deficiency would be associated with worse postoperative outcomes than an iron replete state in adults without anaemia undergoing elective cardiac surgery. METHODS: We performed a prospective, cohort study at two hospitals in Australia. We recruited adults (ie, people 18 years and older) undergoing elective cardiac surgery without anaemia (defined as a haemoglobin of less than 130 g/L for men and less than 120 g/L for women), concomitant haemoglobinopathy, bone marrow pathology, haemochromatosis, or end-stage renal failure requiring dialysis. Participants were stratified as iron deficient or iron replete on the basis of preoperative testing. Iron deficiency was defined as a serum ferritin of less than 100 µg/L or 100-300 µg/L if transferrin saturation was less than 20% or C-reactive protein was more than 5 mg/L. The primary endpoint was days alive and at home at postoperative day 30. The primary analysis included all patients with data available for the primary endpoint and was adjusted for risk measured using EuroSCORE-II and body surface area. The study was prospectively registered with the Australian and New Zealand Clinical Trials Registry, ACTRN12618000185268. FINDINGS: We conducted the study between Feb 21, 2018, and May 7, 2021. We assessed 1171 patients for eligibility and 691 were ineligible; therefore, we enrolled and followed up 480 participants. 240 (50%) were iron deficient and 240 (50%) were iron replete, 95 (20%) were women, 385 (80%) were men, and 453 (94%) were White. Complete data was available for 479 individuals (240 in the iron deficient group and 239 in the iron replete group) for the primary endpoint. The iron deficient group had a median of 22·87 days (IQR 20·65 to 24·06) alive and at home at postoperative day 30, and the iron replete group had a median of 23·18 days (IQR 20·69 to 24·70). The unadjusted difference in medians between the groups was -0·18 days (95% CI -0·73 to 0·36; p=0·51) and the adjusted difference in medians between the groups was -0·11 days (95% CI -0·66 to 0·45; p=0·70). INTERPRETATION: In non-anaemic adults undergoing elective cardiac surgery, our findings suggest that patients with iron deficiency do not have a reduction in days alive and at home at postoperative day 30 compared with patients who have a normal iron status. Routine preoperative investigation for iron deficiency in patients without anaemia undergoing elective cardiac surgery using the definitions we tested might be low-value care. FUNDING: Australian and New Zealand College of Anaesthetists Foundation.

Inclusion, characteristics, and outcomes of male and female participants in large international perioperative studies.

BACKGROUND: We compared baseline characteristics and outcomes and evaluated the subgroup effects of randomised interventions by sex in males and females in large international perioperative trials. METHODS: Nine randomised trials and two cohort studies recruiting adult patients, conducted between 1995 and 2020, were included. Baseline characteristics and outcomes common to six or more studies were evaluated. Regression models included terms for sex, study, and an interaction between the two. Comparing outcomes without adjustment for baseline characteristics represents the 'total effect' of sex on the outcome. RESULTS: Of 54 626 participants, 58% were male and 42% were female. Females were less likely to have ASA physical status ≥3 (56% vs 64%), to smoke (15% vs 23%), have coronary artery disease (21% vs 32%), or undergo vascular surgery (10% vs 23%). The pooled incidence of death was 1.6% in females and 1.8% in males (risk ratio [RR] 0.92; 95% confidence interval [CI]: 0.81-1.05; P=0.20), of myocardial infarction was 4.2% vs 4.5% (RR 0.92; 95% CI: 0.81-1.03; P=0.10), of stroke was 0.5% vs 0.6% (RR 1.03; 95% CI: 0.79-1.35; P=0.81), and of surgical site infection was 8.6% vs 8.3% (RR 1.03; 95% CI: 0.79-1.35; P=0.70). Treatment effects of three interventions demonstrated statistically significant effect modification by sex. CONCLUSIONS: Females were in the minority in all included studies. They were healthier than males, but outcomes were comparable. Further research is needed to understand the reasons for this discrepancy. CLINICAL TRIAL REGISTRATION: International Registry of Meta-Research (UID: IRMR_000011; 5 January 2021).

The association between unanticipated prolonged post-anaesthesia care unit length of stay and early postoperative deterioration: A retrospective cohort study.

This study aimed to investigate whether there was an association between an unanticipated prolonged post-anaesthesia care unit (PACU) length of stay and early postoperative deterioration, as defined as the need for a rapid response team activation, within the first seven days of surgery. We conducted a single-centre retrospective cohort study of adult surgical patients, who stayed at least one night in hospital, and were not admitted to critical care immediately postoperatively, between 1 July 2017 and 30 June 2019. A total of 11,885 cases were analysed. PACU length of stay was significantly associated with rapid response team activation on both univariate (odds ratio (OR) per increment 1.57, 95% confidence intervals (CI) 1.45 to 1.69, P < 0.001) and multivariate analysis (OR per increment 1.41, 95% CI 1.28 to 1.55, P < 0.001). Patients who stayed less than one hour were at low risk of deterioration (absolute risk 3.7%). In patients staying longer than one hour, the absolute increase in risk was small but observable within six hours of PACU discharge. Compar\ed to a one-hour length of stay, a five-hour stay had a relative risk of 4.9 (95% CI 3.7 to 6.1). Other factors associated with rapid response team activation included non-elective surgery (OR 1.78, P < 0.001) and theatre length of stay (OR per increment 1.61, P < 0.001). PACU length of stay was also independently associated with predefined complications and unplanned intensive care unit admission postoperatively. In our cohort, an unanticipated prolonged PACU length of stay of over one hour was associated with an increased incidence of rapid response team activation in the first seven days postoperatively.