Obstructive sleep apnoea (OSA) affects ∼9–24% of the general population, and 90% remain undiagnosed. Those patients with undiagnosed moderate-to-severe OSA may be associated with an increased risk of ...perioperative complications. Our objective was to evaluate the proportion of surgical patients with undiagnosed moderate-to-severe OSA.
After research ethics board approval, patients visiting preoperative clinics were recruited over 4 yr and screened with the STOP-BANG questionnaire. The 1085 patients, who consented, subsequently underwent polysomnography (PSG) (laboratory or portable) before operation. Chart review was conducted in this historical cohort to ascertain the clinical diagnosis of OSA by surgeons and anaesthetists, blinded to the PSG results. The PSG study-identified OSA patients were further classified based on severity using the apnoea–hypopnoea index (AHI) cut-offs.
Of 819 patients, 111 patients had pre-existing OSA and 58% (64/111) were not diagnosed by the surgeons and 15% (17/111) were not diagnosed by the anaesthetists. Among the 708 study patients, PSG showed that 233 (31%) had no OSA, 218 (31%) patients had mild OSA (AHI: 5–15); 148 (21%) had moderate OSA (AHI: 15–30), and 119 (17%) had severe OSA (AHI>30). Before operation, of the 267 patients with moderate-to-severe OSA, 92% (n=245) and 60% (n=159) were not diagnosed by the surgeons and the anaesthetists, respectively.
We found that anaesthetists and surgeons failed to identify a significant number of patients with pre-existing OSA and symptomatic undiagnosed OSA, before operation. This study may provide an impetus for more diligent case finding of OSA before operation.
Previous studies, which relied on hypothetical cases and chart reviews, have questioned the inter-rater reliability of the ASA physical status (ASA-PS) scale. We therefore conducted a retrospective ...cohort study to evaluate its inter-rater reliability and validity in clinical practice.
The cohort included all adult patients (≥18 yr) who underwent elective non-cardiac surgery at a quaternary-care teaching institution in Toronto, Ontario, Canada, from March 2010 to December 2011. We assessed inter-rater reliability by comparing ASA-PS scores assigned at the preoperative assessment clinic vs the operating theatre. We also assessed the validity of the ASA-PS scale by measuring its association with patients' preoperative characteristics and postoperative outcomes.
The cohort included 10 864 patients, of whom 5.5% were classified as ASA I, 42.0% as ASA II, 46.7% as ASA III, and 5.8% as ASA IV. The ASA-PS score had moderate inter-rater reliability (κ 0.61), with 67.0% of patients (n=7279) being assigned to the same ASA-PS class in the clinic and operating theatre, and 98.6% (n=10 712) of paired assessments being within one class of each other. The ASA-PS scale was correlated with patients' age (Spearman's ρ, 0.23), Charlson comorbidity index (ρ=0.24), revised cardiac risk index (ρ=0.40), and hospital length of stay (ρ=0.16). It had moderate ability to predict in-hospital mortality (receiver-operating characteristic curve area 0.69) and cardiac complications (receiver-operating characteristic curve area 0.70).
Consistent with its inherent subjectivity, the ASA-PS scale has moderate inter-rater reliability in clinical practice. It also demonstrates validity as a marker of patients' preoperative health status.
Keywords: COVID-19; postoperative complication; pre-operative evaluation; prognostic study; surgery Article Note: This editorial accompanies a paper by the COVIDSurg Collaborative and GlobalSurg ...Collaborative, Anaesthesia 2021; 76: 748-58. Byline: D. N. Wijeysundera, R. G. Khadaroo
This observational study sought to determine whether the degree of hemodilution during cardiopulmonary bypass is independently related to perioperative acute renal failure necessitating dialysis ...support.
Data were prospectively collected on consecutive patients undergoing cardiac operations with cardiopulmonary bypass from 1999 to 2003 at a tertiary care hospital. The independent relationship was assessed between the degree of hemodilution during cardiopulmonary bypass, as measured by nadir hematocrit concentration, and acute renal failure necessitating dialysis support. Multivariate logistic regression was used to control for variables known to be associated with perioperative renal failure and anemia.
Of the 9080 patients included in the analysis, 1.5% (n = 134) had acute renal failure necessitating dialysis support. There was an independent, nonlinear relationship between nadir hematocrit concentration during cardiopulmonary bypass and acute renal failure necessitating dialysis support. Moderate hemodilution (nadir hematocrit concentration, 21%-25%) was associated with the lowest risk of acute renal failure necessitating dialysis support; the risk increased as nadir hematocrit concentration deviated from this range in either direction (
P = .005). Compared with moderate hemodilution, the adjusted odds ratio for acute renal failure necessitating dialysis support with severe hemodilution (nadir hematocrit concentration <21%) was 2.34 (95% confidence interval, 1.47-3.71), and for mild hemodilution (nadir hematocrit concentration >25%) it was 1.88 (95% confidence interval, 1.02-3.46).
Given that there is an independent association between the degree of hemodilution during cardiopulmonary bypass and perioperative acute renal failure necessitating dialysis support, patient outcomes may be improved if the nadir hematocrit concentration during cardiopulmonary bypass is kept within the identified optimal range. Randomized clinical trials, however, are needed to determine whether this is a cause-effect relationship or simply an association.
Summary
The traditional approach for measuring outcomes after surgery involves ascertaining whether a patient survived surgery while avoiding major complications. This approach does not capture the ...full spectrum of events that are meaningful to patients, especially because mortality risks after elective surgery are relatively low, and different complication types vary considerably with respect to their impact on postoperative recovery. This review discusses the application, advantages, disadvantages and select examples of patient‐centred outcomes in peri‐operative medicine. When applied appropriately, these outcomes complement traditional clinical outcomes, identify important changes in postoperative function that impact patients without discernible complications and ensure that the definition of success after surgery is more meaningful to all relevant stakeholders.
Resting heart rate is well established as a predictor of morbidity and mortality in the general population. However, the relationship between preoperative heart rate and perioperative outcomes, ...specifically myocardial injury, is unclear.
This retrospective cohort study included patients undergoing elective major non-cardiac surgery from 2008 to 2014 at a multisite healthcare system. The exposure was ambulatory heart rate measured during the outpatient preoperative clinic visit, whereas the outcome of interest was myocardial injury (peak postoperative troponin I concentration >30 ng L−1). Covariates included patient characteristics, comorbidities, and preoperative medications. We constructed several multivariable regression models that each modelled heart rate in a different manner, including as a simple continuous variable, categories, and fractional polynomials.
The cohort included 41 140 patients, of whom 4857 (11.8%) experienced myocardial injury. Based on pre-specified heart categories thresholds, a heart rate ≥90 beats min−1 was associated with an elevated odds of myocardial injury compared with a heart rate <60 beats min−1 (adjusted odds ratio, 1.22; 95% confidence interval, 1.06–1.39; P=0.005). This result was consistent regardless of the method used for categorisation. When fractional polynomials were used to model heart rate, a ‘J-shaped’ relationship between heart rate and odds of myocardial injury was observed.
This cohort study found that both very high preoperative heart rates, and possibly also very low heart rates, are associated with increased risk of myocardial injury. Whether heart rate is a modifiable risk factor, or rather simply a marker of underlying cardiac pathology, needs to be determined in further research.
The 6-min walk test (6MWT) is a common means of functional assessment. Its relationship to disability-free survival (DFS) is uncertain.
This sub-study of the Measurement of Exercise Tolerance for ...Surgery study had co-primary outcome measures: correlation of the preoperative 6MWT distance with 30 day quality of recovery (15-item quality of recovery) and 12 month WHO Disability Assessment Schedule scores. The prognostic utility of the 6MWT and other risk assessment tools for 12 month DFS was assessed with logistic regression and receiver-operating-characteristic-curve analysis.
Of 574 patients recruited, 567 (99%) completed the 6MWT. Twelve months after surgery, 16 (2.9%) patients had died and 444 (77%) had DFS. The 6MWT correlated weakly with 30 day 15-item quality of recovery (ρ=0.14; P=0.001) and 12 month WHO Disability Assessment Schedule (ρ=–0.23; P<0.0005) scores. When the cohort was split into 6MWT distance tertiles, the adjusted odds ratio of low vs high tertiles for DFS was 3.13 95% confidence interval (CI): 1.54–6.35. The only independent variable predictive of DFS was the Duke Activity Status Index (DASI) score (adjusted odds ratio: 1.06; P<0.0005). The area under the receiver-operating-characteristic curve for DFS was 0.63 (95% CI: 0.57–0.70) for the 6MWT, 0.60 (95% CI: 0.53–0.67) for cardiopulmonary-exercise-testing-derived peak oxygen consumption, and 0.70 (95% CI: 0.64–0.76) for the DASI score.
Of the risk assessment tools analysed, the DASI was the most predictive of DFS. The 6MWT was safe and comparable with cardiopulmonary exercise testing for all predictive assessments. Future research should aim to determine the optimal 6MWT distance thresholds for risk prediction.
Anaemia is associated with poor postoperative outcomes, but few studies have described the impact of preoperative anaemia in low- and middle- (LMICs), and high-income countries (HICs).
This was a ...planned analysis of data collected during an international 7 day cohort study of adults undergoing elective inpatient surgery. The primary outcome was in-hospital death, and the secondary outcomes were in-hospital complications. Anaemia was defined as haemoglobin <12 g dl−1 for females and <13 g dl−1 for males. Hierarchical three-level mixed-effect logistic regression models were constructed to examine the associations between preoperative anaemia and outcomes.
We included 38 770 patients from 474 hospitals in 27 countries of whom 11 675 (30.1%) were anaemic. Of these, 6886 (17.8%) patients suffered a complication and 198 (0.5%) died. Patients from LMICs were younger with lower ASA physical status scores, but a similar prevalence of anaemia LMIC: 5072 (32.5%) of 15 585 vs HIC: 6603 (28.5%) of 23 185. Patients with moderate odds ratio (OR): 2.70; 95% confidence interval (CI): 1.88–3.87 and severe anaemia (OR: 4.09; 95% CI: 1.90–8.81) were at an increased risk of death in both HIC and LMICs. Complication rates increased with the severity of anaemia. Compared with patients in LMICs, those in HICs experienced fewer complications after an interaction term analysis LMIC (OR: 0.92; 95% CI: 0.87–0.97) vs HIC (OR: 0.86; 95% CI: 0.84–0.87); P<0.01.
One-third of patients undergoing elective surgery are anaemic. These patients have an increased risk of complications and death. The prevalence of anaemia is similar amongst patients in LMICs despite their younger age and lower risk profile.
ISRCTN51817007.
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