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.

Are positive-pressure ventilation lobby rooms effective for protective and source isolation?

High-efficiency particulate air supplied to a positive-pressure ventilation lobby (PPVL) in isolation rooms offers the dual advantage of protective and source isolation. This study demonstrates the in-use validity of PPVL rooms for protective isolation of patients. Of the 48 PPVL air samples investigated, Aspergillus fumigatus was detected from only one (2%) sample. Local and remote monitoring of the PPVL rooms is essential for the safety of patients and healthcare workers. Remote and point-of-use engineering controls are essential for ongoing ventilation monitoring, but this should be complemented by visual inspection of the isolation suite. Periodic microbiological monitoring should also be considered with other control measures.

A quality improvement approach to optimizing infusion wait times

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Background: Long wait times are a common and occasionally unavoidable experience for patients receiving chemotherapy infusions. It unfavorably impacts patient satisfaction and clinic efficiency. Our primary objective was to evaluate the impact of infusion clinic process changes on patient wait times within a Plan, Do, Study, Act (PSDA) framework. Methods: A multi-disciplinary team, consisting of oncology, nursing, pharmacy, quality improvement, and support staff, met to have brainstorming sessions, make surveys, and conduct time studies to analyze our current process (Plan). A Pareto chart created using survey results showed communication issues were likely causing the largest modifiable impact on our wait times. A common source of miscommunication was whether patients are waiting on labs results for treatment. Beginning March 2019, patients not requiring labs on the day of treatment were assigned to a separate scheduling title to designate them as priority for vital signs and review by pharmacy (Do). Upon clinic check-in, these patients now have vitals signs collected immediately and pharmacy is notified of their arrival to begin chemotherapy preparation. Results: Baseline as well as prospective wait time data was collected from 30 clinic days (360 patient wait times) from chart reviews and timestamp data available in the electronic medical record (EMR). Results were analyzed (Study) using Statistical Process Control (SPC) charts to allow for early detection of improvement. Pre-implementation wait times averaged 1 hour and 37 minutes. Post implementation wait times average 1 hour and 16 minutes (Act). This change was significant based on a shift visible on the SPC chart. Our balancing measure of wait times for all patients did not increase compared to baseline (2 hours and 15 minutes). No significant correlation was observed between average daily wait times and the day of the week or the number of patients treated that day at baseline. Conclusions: Implementation of a new clinic scheduling title and workflow reduced wait times for patients not requiring labs on the day of treatment without increasing wait times for patients requiring labs. Additional PDSA cycles will be conducted for further reductions in wait times for all patients at our site.

Signaling mediated by the NF-κB sub-units NF-κB1, NF-κB2 and c-Rel differentially regulate Helicobacter felis-induced gastric carcinogenesis in C57BL/6 mice

The classical nuclear factor-kappaB (NF-κB) signaling pathway has been shown to be important in a number of models of inflammation-associated cancer. In a mouse model of Helicobacter-induced gastric cancer, impairment of classical NF-κB signaling in the gastric epithelium led to the development of increased preneoplastic pathology, however the role of specific NF-κB proteins in Helicobacter-associated gastric cancer development remains poorly understood. To investigate this C57BL/6, Nfkb1^−/−, Nfkb2^−/− and c-Rel^−/− mice were infected with Helicobacter felis for 6 weeks or 12 months. Bacterial colonization, gastric atrophy and preneoplastic changes were assessed histologically and cytokine expression was assessed by qPCR. Nfkb1^−/− mice developed spontaneous gastric atrophy when maintained for 12 months in conventional animal house conditions. They also developed more pronounced gastric atrophy after short-term H. felis colonization with a similar extent of preneoplasia to wild-type (WT) mice after 12 months. c-Rel^−/− mice developed a similar degree of gastric atrophy to WT mice; 3 of 6 of these animals also developed lymphoproliferative lesions after 12 months of infection. Nfkb2^−/− mice developed minimal gastric epithelial pathology even 12 months after H. felis infection. These findings demonstrate that NF-κB1- and NF-κB2-mediated signaling pathways differentially regulate the epithelial consequences of H. felis infection in the stomach, while c-Rel-mediated signaling also appears to modulate the risk of lymphomagenesis in gastric mucosa-associated lymphoid tissue.

The immunohistochemical characterization of devil facial tumor disease (DFTD) in the Tasmanian Devil (Sarcophilus harrisii)

Immunohistochemical techniques were used to characterize the disfiguring and debilitating fatal neoplastic disease, devil facial tumor disease (DFTD), which has recently affected a significant proportion of the wild population of Tasmanian Devils (Sarcophilus harrisii). The diagnostic values of a number of immunohistochemical stains were employed to further characterize 50 representative cases. The neoplasms were negative for cytokeratin (0/48), epithelial membrane antigen (0/42), von Willebrand factor (vWF) (0/11), smooth muscle actin (SMA) (0/26), desmin (0/47), glial fibrillary acid protein (0/13), CD16 (0/13), CD57 (0/43), CD3 (0/18), and LSP1 (0/16). DFTD cells were positive for vimentin (50/50), S-100 (41/48), melan A (11/39), neuron specific enolase (35/35), chromogranin A (12/12) and synaptophysin (29/30). The cells were negative for amyloid (0/30) and stained negatively with Singh's silver (0/34) but were weakly argyrophilic (3/40) using Grimelius histochemical stain. These staining characteristics are consistent with cells of neuroectodermal origin.

Efficacy of oryzalin and associated histological changes in Cryptosporidium-infected neonatal rats

This paper reports the anti-cryptosporidial effects of, and concomitant amelioration of the histological changes in the gut of neonatal rats with intestinal cryptosporidiosis treated with the dinitroaniline, oryzalin. The ED50 was determined to be 7 mg/kg using twice daily doses administered for 3 consecutive days. A maximum inhibition of 85.5% was achieved at 25 mg/kg and this inhibition remained constant despite increasing the oryzalin dose to 200 mg/kg. Cryptosporidiosis significantly decreased the intestinal villus/crypt (VC) ratio by approximately 50% (duodenum = 2.3, jejunum = 2.5 and ileum = 1.7) when compared to uninfected untreated controls (duodenum = 4.3, jejunum = 5.9 and ileum = 4.5). Treatment with oryzalin doubled the VC ratio in the duodenum, jejunum and ileum following doses of 5 mg, 50 mg and 200 mg/kg respectively. Oryzalin concentrations in the small intestine contents and plasma were determined, using HPLC, at 0.5, 1 and 2 h after dosing. The much greater dose required to return VC ratios to normal in the ileum (200 mg/kg) compared to the duodenum (6.25 mg/kg) appeared to reflect the decreased concentration of the drug in the distal small intestine. Concentrations of oryzalin equivalent to the in vitro IC50 were maintained for 2 h in the first half of the small intestine following a single dose of 100 mg/kg.

Atypical multiple, papilliform, xanthomatous, cutaneous neoplasia in a goose (Anser anser)

An 18-month-old, male greylag goose was presented for assessment of multiple, semi-pedunculated cutaneous masses limited to non-feathered areas of skin. Initial biopsy and histopathology revealed a mesenchymal neoplasm suggestive of lipoblastomatosis or atypical xanthoma. Immunohistochemistry was unsuccessful in determining the tissue type of origin. Surgical resection of all masses was prevented by the mucocutaneous location of several masses. Chemotherapy using intralesion cisplatin was unsuccessful in resolving the masses but was well-tolerated by the goose. Serum lipid and lipoprotein analysis revealed a persistent hypercholesterolaemia and hypertriglyceridaemia without biochemical evidence of an underlying metabolic disease. The persistent hyperlipidaemia may have contributed to the formation of the masses identified in this case.

Focal eosinophilic proctitis with associated rectal prolapse in a pony

Focal intramural nodules were palpated in the rectal wall of a 12-year-old pony mare presented for rectal prolapse. Eosinophilic proctitis was diagnosed by examination of fine needle aspirates and biopsy of the largest rectal nodule. After treatment with a course of corticosteroids, the rectal nodule and accompanying peripheral eosinophilia resolved. There was no recurrence of the condition during the follow-up period of 20 months. Focal eosinophilic proctitis appeared to be an unusual cause of tenesmus and rectal prolapse in this case.

High-level dystrophin expression after adenovirus-mediated dystrophin minigene transfer to skeletal muscle of dystrophic dogs: prolongation of expression with immunosuppression

Replication-deficient adenovirus vectors (AdV) have been successfully used to transfer a truncated human dystrophin cDNA to skeletal muscle of dystrophin-deficient mdx mice. A dystrophin-deficient golden retriever dog model (GRMD) has been identified, which, unlike the mouse model, leads to a clinicopathological phenotype similar to that of Duchenne muscular dystrophy (DMD). We show for the first time that high-level dystrophin expression in skeletal muscle of GRMD dogs can be achieved by AdV-mediated gene transfer. However, a humoral and cellular immune response of the host against antigens of viral and transgene origin (similar to that occurring in mdx mice after AdV-mediated dystrophin gene transfer) leads to a decline of dystrophin expression over a 2-month period. Immunosuppression by cyclosporin significantly prolonged transgene expression. The GRMD model may help to solve the open questions pertaining to dystrophin gene transfer such as systemic delivery and improvement of muscle function before human trials for gene replacement therapy in DMD may be considered.

Direct dystrophin and reporter gene transfer into dog muscle in vivo

Bacterial beta-galactosidase cDNA was injected without lipofectin into 41 sites in dog muscle and expression was seen in 22 of them. The cDNA and lipofectin was injected into 35 similar sites and expression was seen in 21. Expression was seen in a maximum of 2.5% of muscle fibers and 23.21% of nonmuscle cells. A total of 106 muscle sites were injected with the minigene with and without lipofectin. In 4 of the 45 sites injected with the minigene without lipofectin human dystrophin was expressed around the periphery of 0.3% of the fibers. Bacterial beta-galactosidase cDNA was injected into the peritoneal cavity of 4 pups, 2 of which also received lipofectin. In all 4, expression was seen in liver, spleen, and mesenteric lymph node. In the 2 pups that received lipofectin, expression was also seen in the diaphragm, intercostal, and abdominal muscles of 1 and in the diagphragm and intercostal muscles of the other. These experiments show that human dystrophin transgene expression can be obtained in dog muscle. However, other methods will be required to increase the degree of expression before gene therapy trials can be undertaken.

Improving the performance of liquid-crystal-over-silicon spatial light modulators: issues and achievements

The performance of liquid-crystal-over-silicon spatial light modulators has advanced rapidly in recent years. Most progress has centered around new device designs with increased bandwidth. In this paper we report on a number of techniques to improve the optical quality; these have applications in both current and future devices.

Mirror quality and efficiency improvements of reflective spatial light modulators by the use of dielectric coatings and chemical-mechanical polishing

To date, silicon backplane spatial light modulators have been characterized by poor-quality mirrors. Hillock formation during metal sintering has been identified as the source of this problem. Here hillock elimination is achieved by constraining the metal with a low-temperature plasma-enhanced chemicalvapor deposition silicon dioxide coating. A double-layer metallization procedure increases the silicon area available for circuitry and improves the mirror fill factor. Second-layer metal mirrors require a flat, intermediate dielectric substrate. Chemical-mechanical polishing is demonstrated to provide the flatness necessary to achieve high optical quality.