Distribution of aldoxime dehydratase in microorganisms

The distribution of phenylacetaldoxime-degrading and pyridine-3-aldoxime-degrading ability was examined with intact cells of 975 microorganisms, including 45 genera of bacteria, 11 genera of actinomyces, 22 genera of yeasts, and 37 genera of fungi, by monitoring the decrease of the aldoximes by high-pressure liquid chromatography. The abilities were found to be widely distributed in bacteria, actinomyces, fungi, and some yeasts: 98 and 107 strains degraded phenylacetaldoxime and pyridine-3-aldoxime, respectively. All of the active strains exhibited not only the aldoxime-dehydration activity to form nitrile but also nitrile-hydrolyzing activity. On the other hand, all of 19 nitrile-degrading microorganisms (13 species, 7 genera) were found to exhibit aldoxime dehydration activity. It is shown that aldoxime dehydratase and nitrile-hydrolyzing activities are widely distributed among 188 aldoxime and 19 nitrile degraders and that the enzymes were induced by aldoximes or nitriles.

Isolation and characterization of a bacterium possessing a novel aldoxime-dehydration activity and nitrile-degrading enzymes

A bacterial strain capable of utilizing E-pyridine-3-aldoxime as a nitrogen source was isolated from soil after a 4-month acclimation period and was identified as Rhodococcus sp. The strain contained a novel aldoxime dehydration activity that catalyzed a stoichiometric dehydration of E-pyridine-3-aldoxime to form 3-cyanopyridine. The enzyme activity was induced by various aldoximes and nitriles. The strain metabolized the aldoxime as follows: E-pyridine-3-aldoxime was dehydrated to form 3-cyanopyridine, which was converted to nicotinamide by a nitrile hydratase, and the nicotinamide was successively hydrolyzed to nicotinic acid by an amidase.

The effects of intravenous clonidine on ventilation

The effects of clonidine, an alpha 2 adrenergic agonist, on ventilation were studied in a group of adult volunteers. The ventilatory variables measured were minute ventilation, respiratory rate, end-tidal carbon dioxide tension and the response to carbon dioxide challenge. We found no differences in minute ventilation, respiratory rate and end-tidal carbon dioxide tension, before and after clonidine administration. However, the ventilatory response to carbon dioxide was significantly attenuated following clonidine, suggesting that clonidine has respiratory depressant effects.

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Background

Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice.

Methods

COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien–Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement.

Results

Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001).

Conclusion

Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk.

Appendicitis risk prediction models in children presenting with right iliac fossa pain (RIFT study): a prospective, multicentre validation study

BACKGROUND

Acute appendicitis is the most common surgical emergency in children. Differentiation of acute appendicitis from conditions that do not require operative management can be challenging in children. This study aimed to identify the optimum risk prediction model to stratify acute appendicitis risk in children.

METHODS

We did a rapid review to identify acute appendicitis risk prediction models. A prospective, multicentre cohort study was then done to evaluate performance of these models. Children (aged 5-15 years) presenting with acute right iliac fossa pain in the UK and Ireland were included. For each model, score cutoff thresholds were systematically varied to identify the best achievable specificity while maintaining a failure rate (ie, proportion of patients identified as low risk who had acute appendicitis) less than 5%. The normal appendicectomy rate was the proportion of resected appendixes found to be normal on histopathological examination.

FINDINGS

15 risk prediction models were identified that could be assessed. The cohort study enrolled 1827 children from 139 centres, of whom 630 (34·5%) underwent appendicectomy. The normal appendicectomy rate was 15·9% (100 of 630 patients). The Shera score was the best performing model, with an area under the curve of 0·84 (95% CI 0·82-0·86). Applying score cutoffs of 3 points or lower for children aged 5-10 years and girls aged 11-15 years, and 2 points or lower for boys aged 11-15 years, the failure rate was 3·3% (95% CI 2·0-5·2; 18 of 539 patients), specificity was 44·3% (95% CI 41·4-47·2; 521 of 1176), and positive predictive value was 41·4% (38·5-44·4; 463 of 1118). Positive predictive value for the Shera score with a cutoff of 6 points or lower (72·6%, 67·4-77·4) was similar to that of ultrasound scan (75·0%, 65·3-83·1).

INTERPRETATION

The Shera score has the potential to identify a large group of children at low risk of acute appendicitis who could be considered for early discharge. Risk scoring does not identify children who should proceed directly to surgery. Medium-risk and high-risk children should undergo routine preoperative ultrasound imaging by operators trained to assess for acute appendicitis, and MRI or low-dose CT if uncertainty remains.

FUNDING

None.

Extra inspiratory work of breathing imposed by cricothyrotomy devices

Using a lung model for spontaneous ventilation, we have assessed the additional work of inspiration imposed by a variety of cannulae ranging from the 12- and 14-gauge intravascular cannulae to the 8.0-mm i.d. adult tracheostomy tube. Work (W) ranged between 9 and 2262 mJ litre-1 and power (W) between 0.2 and 37.7 mW litre-1 min; the smallest values were obtained with the 8.0-mm i.d. adult tracheostomy tube and the 12- and 14-gauge intravascular cannulae gave the largest values. With any given cannula, W and W were influenced by ventilation (tidal volume and frequency) and ventilatory wave pattern of the analogue lung. The results obtained from the 12- and 14-gauge cannulae represent what is probably an excessive inspiratory workload, whereas the other four devices (Portex MiniTrach, 4.0, 6.0 and 8.0 tracheostomy tubes) may be suitable in the short term for relieving airway obstruction and compatible with spontaneous ventilation.

New agents, the circle system and short procedures

Sevoflurane, desflurane and isoflurane were compared using a circle system in 97 patients undergoing short surgical procedures. Using initial high flows, the time intervals to equilibration between inspired and end-expired agent concentrations were measured; equilibration was defined as FE/FI = 0.8. The mean (SD) times obtained for sevoflurane, desflurane and isoflurane were 8.2 (2.1) min, 3.8 (0.7) min and 19.7 (6.5) min, respectively. These times were significantly different from each other (p < 0.0001). After equilibration total flow were reduced to 500 ml.min-1; at these flows the initial decline in end-expired agent concentration was minimal with desflurane, intermediate with sevoflurane and greatest with isoflurane. Both desflurane and sevoflurane are appropriate for efficient use of the circle system during short anaesthetics.

BJS commission on surgery and perioperative care post-COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) was declared a pandemic by the WHO on 11 March 2020 and global surgical practice was compromised. This Commission aimed to document and reflect on the changes seen in the surgical environment during the pandemic, by reviewing colleagues' experiences and published evidence.

METHODS

In late 2020, BJS contacted colleagues across the global surgical community and asked them to describe how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had affected their practice. In addition to this, the Commission undertook a literature review on the impact of COVID-19 on surgery and perioperative care. A thematic analysis was performed to identify the issues most frequently encountered by the correspondents, as well as the solutions and ideas suggested to address them.

RESULTS

BJS received communications for this Commission from leading clinicians and academics across a variety of surgical specialties in every inhabited continent. The responses from all over the world provided insights into multiple facets of surgical practice from a governmental level to individual clinical practice and training.

CONCLUSION

The COVID-19 pandemic has uncovered a variety of problems in healthcare systems, including negative impacts on surgical practice. Global surgical multidisciplinary teams are working collaboratively to address research questions about the future of surgery in the post-COVID-19 era. The COVID-19 pandemic is severely damaging surgical training. The establishment of a multidisciplinary ethics committee should be encouraged at all surgical oncology centres. Innovative leadership and collaboration is vital in the post-COVID-19 era.

An evaluation of oxygen delivery using nasal prongs

Oxygen delivery using nasal prongs was assessed using a lung model for spontaneous ventilation. The analogue lung was attached to a manikin, which provided a model of the 'face and pharynx' to which the nasal prongs were applied. Oxygen concentrations were measured in the model trachea at varying fresh gas inflow and peak inspiratory flows. The study demonstrated enormous variability in the both the peak-inspired (26.3-90.0%) and end-expired concentrations (25.2-78.6%) of oxygen delivered to the trachea. There was a regular relationship between the ratio of peak inspiratory flows, expressed over fresh gas inflow and the end-expired oxygen concentrations which could allow estimation of inspired oxygen concentration.

A high flow semi-open system for preoxygenation: an evaluation

We have compared an alternative breathing system for preoxygenation comprising a Hudson face mask with high oxygen inflow (48 litre min-1) and a Mapleson A breathing system (100 ml kg-1 min-1). The study consisted of two parts: the first involved adult volunteers (10 male, seven female) and the second part used a lung model for spontaneous ventilation with a sinusoidal ventilatory wave pattern. In the volunteers, preoxygenation was achieved at mean times of 138 (SD 31.3) s and 164 (SD 36.7) s with the high flow semi-open and Mapleson A systems, respectively. In the lung model, at peak inspiratory flow rates of 30 and 40 litre min-1, the preoxygenation times were 139 and 120 s, respectively, with the semi-open system and 167 and 156 s with the Mapleson A system. The high flow semi-open system may be an alternative for current techniques, provided peak inspiratory flows are not excessive.

Anaesthesia and the Internet

The Internet is a network of computers that allows rapid transfer of information throughout the world. The number of medical, and particularly anaesthetic, resources is rapidly increasing. This article briefly describes the Internet and its features which may be of interest to anaesthetists and intensivists in the United Kingdom, together with some of the tools for working with them.

Pre-oxygenation: the Hudson mask as an alternative technique

The use of a simple oxygen facemask (Hudson) with high oxygen inflow (48 l.min-1) was investigated as a technique for pre-oxygenation, comparing it with the Magill system (oxygen flow: 100 ml.kg-1.min-1). One hundred and thirty-eight patients scheduled for elective gynaecological and orthopaedic surgery were studied: group 1, Hudson mask and group 2, Magill system (ASA 1-2, n = 107); group 3, Hudson mask and group 4, Magill system (ASA 3, n = 30). Pre-oxygenation was assessed by measuring the times to 97%, 95% and 93% arterial desaturation (finger pulse oximetry) following 3 min of pre-oxygenation. The times taken to achieve these end-points in all the study groups suggest that the Hudson mask offers an alternative technique for pre-oxygenation.

The parallel Lack anaesthetic breathing system

The parallel Lack system is a new modification of the Mapleson A system comprising separate inspiratory and expiratory tubes. To determine that the function of the system was that anticipated of a Mapleson A, the fresh gas flow requirements to prevent rebreathing during spontaneous ventilation were assessed in three situations: (1) a lung model (2) conscious volunteers and (3) anaesthetised patients. Two sets of criteria to define rebreathing were used; (A) those based on changes in ventilation or end-expired carbon dioxide tension and (B) minimum inspired carbon dioxide tension. Using A, rebreathing occurred at a fresh gas flow to minute ventilation ratio (VF/VE) of 0.75 for the lung model, and 0.73 for conscious volunteers. These results were comparable to those obtained for a Magill attachment. They were also close to the point at which mechanical dead space began to increase in the lung model. Criteria B gave much lower values for the onset of rebreathing. Rebreathing was present by criteria A in five of the six anaesthetised patients at a fresh gas flow of 60 ml.kg-1.min-1 (VF/VF of 0.78). The results confirm that the parallel Lack behaves as a Mapleson A system. The resistance to breathing posed by the parallel Lack was also comparable to the Magill system.

The additional work of breathing imposed by Mapleson A systems

The additional work attributable to breathing through five Mapleson A anaesthetic breathing systems (Magill, Lack, Parallel Lack, Humphrey ADE and Enclosed Magill) was studied using a lung model. With all five systems, the additional work was found to be a function of fresh gas flow, respiratory flow as well as system geometry. Within the range of fresh gas flow and respiratory flow studied, the additional work ranged between 80 mJ.l-1 and 182 mJ.l-1. Expiratory work was always greater than the inspiratory workload. Increasing fresh gas inflow into the system increases expiratory work, both resistive and elastic components. The Magill system posed the least work expenditure. The values for the additional work obtained with the lung model were of the same order of magnitude when measurements were taken in volunteers.

Fresh gas flow requirements during spontaneous ventilation: fresh gas flow to total ventilation ratio or ml kg-1 min-1?

Both the performance of breathing systems and recommendations for the fresh gas flows to be used in patients breathing spontaneously can be expressed in ml kg-1 min-1 or fresh gas: total ventilation ratio (VF:VE). We have examined the relationship between these two descriptions. The data of 106 subjects (awake volunteers and anaesthetized patients) were retrieved from the archives of previous work performed in our department. The two methods of describing the requisite fresh gas produced different results, with correlation coefficients (r) between the methods of r = 0.69 and r = 0.49 for the awake and anaesthetized groups, respectively. The results of the multiple regression models suggest that both baseline total ventilation and body weight may be used to predict the fresh gas flow requirements, but residual analysis did not discriminate which method was a better predictor.

Nitrous oxide administration using commonly available oxygen therapy devices

Administration of nitrous oxide is useful for providing sedation and analgesia. The therapeutic range for nitrous oxide is 20-30%. Several oxygen treatment devices have been used for administering nitrous oxide, but little is known about the concentrations of nitrous oxide and oxygen delivered to the trachea. We have studied this, using an analogue lung model, with several oxygen therapy devices. With a 1:1 nitrous oxide-oxygen mixture in the primary flow for all systems, end-expired nitrous oxide concentrations varied between 6.5% and 34.3%. Therapeutic concentrations were produced using the Hudson (nominal oxygen concentration 60%) fixed-performance mask, the variable performance Hudson mask at 4 litre min-1, the MC masks at 4 and 6 litre min-1 and the nasal prongs at 6 and 8 litre min-1. Simultaneous end-expired oxygen concentrations for all devices tested were within a safe range.

1559 Motivations of Medical Students and Doctors Leaving the NHS Explored in a Residency Training Application Webinar Series

Aim

Traditionally, the UK has been highly regarded as a place for doctors to pursue undergraduate medical training and postgraduate training. However, recent reports show that more than 40% of UK-graduate doctors leave the country to pursue specialty training elsewhere. This paper aims to identify and evaluate the motivating factors for UK graduates to leave the NHS.

Method

An anonymised questionnaire was disseminated at a webinar series regarding the application process to pursue residency overseas. The data was independently analysed by two reviewers. A one-way ANOVA (with Tukey’s Post Hoc test) was utilised to compare the difference between motivating factors. Results were considered statistically significant for p-values &lt;0.05.

Results

1,118 responses from the UK medical students and doctors were collected; of which, 1,001 (89.5%) were medical students, and 88 (7.9%) were junior doctors. There was a higher preference for leaving after the Foundation Programme compared to the other periods (p &lt; 0.0001). There was no difference between leaving after core surgical/medical training and specialty training (p = 0.549). However, both were significantly higher than leaving the NHS after medical school (p &lt; 0.0001). Quality of life and financial prospects (both P-corrected&lt;0.0001 compared individually and to other groups) were the most agreed reasons to leave the NHS, followed by clinical and academic opportunities and, subsequently, family reasons.

Conclusions

Future work on the quality of life for doctors in the UK, especially for prospective surgical trainees, should be explored. Policymakers should focus on assessing the difference in working hours, on-call hours or wages that may differ among the healthcare systems.

467 Impact of the Coronavirus Pandemic on Acute Surgical Patients’ Discharge Summaries

Background

The emergence of the Coronavirus pandemic has placed increased demands on the NHS workforce, especially in medical and intensive care units. The subsequent redistribution of surgical house officers to accommodate this in a single centre has possibly negatively impacted on the effective discharge notification of acute surgical patients.

Methods:

Discharge summaries of all patients discharged from a Surgical Assessment Unit were collected and analysed, to identify the date of completion and grade of responsible clinician. Data collection was carried out over three weeks before the initiation of lockdown measures and continued for a further three weeks during the peak of the Coronavirus pandemic with a three-week interventional period in between.

Results

In the initial audit, 36.2% of the 246 patients had delayed discharge summaries with an average of 7 days to complete. On re-evaluation, 45.3% of the 223 patients had delayed discharge summaries, with an average of 12 days to complete. A survey conducted post-re-audit identified that the most common reason for this was due to time constraints.

Conclusions

The reallocation of surgical staff has affected communication between primary and secondary care. Given the potential repercussions of these delays, healthcare systems should be made aware of this consequence, especially in preparation for any future resurgences.

224 A 5-Year Observational Study on Distal Femoral Periprosthetic Fractures in Elderly Patients in a Single Institution: Distal Femoral Replacement vs. Internal Fixation

Aim

To evaluate the outcome of distal femoral replacements versus internal fixation for elderly patients with distal femoral periprosthetic fracture in a single institution.

Method

A five-year retrospective observational study was conducted of a consecutive series of patients with distal femoral periprosthetic fracture who underwent either distal femoral replacement (DFR) or internal fixation (IF) in a tertiary referral centre. Clinical information analysed included patient demographics, co-morbidities, interval between primary total knee arthroplasty (TKA) to distal femoral periprosthetic fracture, type of fracture, operative technique, preoperative ASA grade, post-operative complications, intensive therapy unit (ITU) stay, length of hospital stay (LOS), re-fixation and mortality.

Results

Study included 27 patients of which fourteen patients underwent a DFR while 13 underwent an IF. 89% of the patients were females. Mean age of the patients at the time of fracture was 85 versus 80 (DFR vs IF). The mean interval from the primary TKA to the fracture were 80 months (range 0-181). There were no intraoperative complications in either group. Three patients required ITU stay from the DFR group while one patient from the IF group required re-fixation. Median LOS was 56 days (range 9-144) after DFR and 55 days (range 4-83) after IF. There was one 30-day mortality in the DFR group. One-year mortality for the DFR group was 7% vs 15% for the IF group.

Conclusions

In our study, DFR and IF were observed to have similar LOS with a higher mortality in the IF group at one year. There was one re-fixation in the IF group.

The cuffed pharyngeal airway

A new self-retaining nasopharyngeal airway is described. The clinical performance of this airway was assessed in 100 patients during anaesthesia with spontaneous respiration. The physical behaviour of the airway was investigated in four patients. In an additional 25 patients the tube was used via the oral route. Although designed for use by the nasal route, the airway can be used as a self-retaining oropharyngeal airway.

Nitrous Oxide-Oxygen Analgesia: The Performance of the MC Mask Delivery System

Nitrous oxide administration via an oxygen facemask such as the Mary Catterall (MC) is an accepted technique for supplementing regional anaesthesia. This study assessed the range of nitrous oxide and oxygen concentrations delivered to the trachea using a mechanical lung model. The inspired concentrations of these two gases were determined by the total fresh gas inflow rates, their concentrations in the fresh gas mixture and the peak inspiratory flow rate of the analogue lung. A 1: 1 nitrous oxide-oxygen mixture in the fresh gas with an inflow rate of 4–6 1/min is recommended to ensure adequate oxygen delivery into the trachea as well as achieving the therapeutic concentrations of nitrous oxide (20–30%).