Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Frozen section analysis for organ-conserving surgery in penile cancer: Assessing oncological outcomes and trends of local recurrence

Introduction and objectives:

The local recurrence rate of penile cancer following surgical excision is reported in many series to be between 6 and 29%. Intra-operative frozen section (FS) is a useful tool to ensure safe microscopic margins in organ-sparing procedures in penile cancer. In this series, we assessed the rates of positive margins and patterns of local recurrence in a multicentre cohort of patients undergoing penile-preserving surgery assisted by intra-operative FS analysis.

Materials and methods:

We reviewed all those patients for whom intra-operative FS was employed during penile-preserving surgery in three tertiary referral centres between 2003 and 2016. We assessed whether the use of FS altered the surgical technique and what affect it had on positive margins and recurrence rates.

Results:

A total of 169 patients were identified. Of these, intra-operative FS examination of the surgical margin was positive in 21 (12%) cases. Final histological examination confirmed cancer-free margins in all but one patient (99.4%). Overall, 9 patients developed local recurrence (5.3%).

Conclusions:

In this series, intra-operative FS contributed to a very low rate (5.3%) of local recurrence. We noted an extremely low positive margin rate (0.6%) which highlights the benefit of incorporating FS analysis into organ-preserving surgery for penile cancer.

Level of evidence:

Not applicable for this multicentre audit.

Tuberculosis in goats on a farm in Ireland: epidemiological investigation and control

This paper describes an outbreak of tuberculosis (TB) caused by Mycobacterium bovis in a dairy goat herd on a farm in Ireland, where 66.3 per cent of the herd tested positive to the single intradermal comparative tuberculin test (SICTT) at initial detection. An epidemiological investigation was conducted to determine the origin of the outbreak, considering issues such as animal movements and herd management practices. Infection was introduced with a consignment of goats, as determined by the variable number tandem repeat profile. Infection was eradicated using a test and cull programme involving the SICTT, the interferon-γ assay and a multiplex immunoassay (Enferplex TB).

The effect of patient position on the reproducibility of cardiac output measurements

OBJECTIVE

To determine the effect of patient position on the reproducibility of cardiac output measurements.

DESIGN

Prospective, two-group quasi-experimental design. Convenience sample.

SETTING

The study involved two intensive care units in two adult acute care hospitals.

PATIENTS

Thirty patients admitted to the intensive care unit who had a thermodilution pulmonary artery catheter in place. Ages ranged from 39 to 80 years (mean of 66.4 +/- 11.3 years).

OUTCOME MEASURES

Thermodilution cardiac output measurements.

INTERVENTION

The subjects were placed in one of two groups, initially by flipping a coin then into alternate groups. Group A subjects were placed supine, and after 5 minutes had cardiac output measurements performed. They were then placed in the 45-degree upright position, and after an additional 5 minutes had cardiac output measurements performed. Group B subjects were first placed in the 45-degree upright position, and after 5 minutes had cardiac output measurements performed. They were then placed in the supine flat position, and after an additional 5 minutes had cardiac output measurements performed.

RESULTS

Seventy percent (n = 30) of the sample population displayed a lower cardiac output in the 45-degree upright position than that obtained in the supine position, with the decrease ranging from 1% to 32% (mean decrease 11%). Forty percent (n = 30) of cardiac output measurements obtained in the 45-degree upright were greater than or equal to 10% less than those obtained in the supine flat position. The differences in cardiac output were analyzed with the paired t test. which produced a 95% confidence interval from -0.539 to -0.083. The two-group Wilcoxon test was used to analyze the mean cardiac output with the patient in the supine, flat position and in the 45-degree upright position. The mean cardiac output at 0 degrees was found to be statistically significant higher (p = 0.0083) than the mean cardiac output at 45 degrees. The effect of coexisting variables was analyzed with the Kruskal-Wallis. The use of vasoconstrictors was the only variable that had a statistically significant change in cardiac output associated with a change in position.

CONCLUSIONS

These results indicate that cardiac output measurements are affected by alterations in patient position. To ensure accurate comparisons between consecutive cardiac output measurements, the researchers recommend that the position in which the cardiac output measurements are performed be documented and the cardiac output measurements be conducted in a uniform position.

Myocardial and peripheral catecholamine responses to acute coronary artery constriction before and after propranolol treatment in the anaesthetised dog

The left anterior descending coronary artery was constricted for eight minutes on two occasions in 13 anaesthetised open-chest dogs. One group (n = 8) was studied before and afer 1 mg . kg-1 propranolol intravenously; a second group (n = 5) served as controls. Simultaneous blood samples were drawn from arterial and coronary sinus catheters for measurement of lactate and catecholamine concentrations. In controls, coronary artery constriction resulted in a reproducible fall in fractional myocardial lactate extraction and an increase in left atrial pressure, but caused no significant changes in blood pressure, heart rate or plasma concentrations of noradrenaline, adrenaline, or dopamine. In the treated group, heart rate was reduced but blood pressure was the same after propranolol; both remained unchanged during constriction and after release. The fall in fractional lactate extraction was abolished by propranolol. Arterial noradrenaline increased significantly after propranolol, fell during constriction and rose again after release. A similar trend was observed in coronary sinus noradrenaline. Reversible myocardial ischaemia is not associated with peripheral or myocardial release of catecholamines. Pre-treatment with propranolol appears to exert a protective effect on the myocardium even during reversible ischaemia. Although peripheral noradrenaline levels are increased after propranolol, this increase is not maintained during coronary artery constriction.