The influence of changes in blood flow on the accuracy of pulse oximetry in humans

Oxygen saturation (SpO2) was measured with a pulse oximeter in ten healthy, young men breathing air. A pulse oximeter probe was attached to the second toe and a laser Doppler probe to the first toe of the same foot for measurement of changes in peripheral blood flow. The pulse oximeter and laser Doppler readings were simultaneously compared when the foot was positioned 40 cm (position 1) above heart level, elevated 10 cm (position 2) above heart level and horizontally at heart level (position 3). Using this experimental human model, we achieved various blood flows. The AC and DC optical signals used for determination of oxygen saturation were recorded from the pulse oximeter and analysed. There was a significant increase (P less than 0.05) between position 1 and 3 in blood flow as measured by the laser Doppler flow meter. The corresponding pulse oximeter readings of haemoglobin saturation also increased significantly (P less than 0.05) comparing these two leg positions. Analysing the AC- and DC optical signals, the AC value of infrared light increased considerably, while the AC value of the red light decreased slightly. The DC values of red and infrared light did not change significantly. In summary, when blood flow was decreased, the ratio of red to infrared transmitted light was changed, resulting in a low SpO2 reading.     

Factors associated with mortality in patients with COVID-19 admitted to intensive care: a systematic review and meta-analysis

Identification of high-risk patients admitted to intensive care with COVID-19 may inform management strategies. The objective of this meta-analysis was to determine factors associated with mortality among adults with COVID-19 admitted to intensive care by searching databases for studies published between 1 January 2020 and 6 December 2020. Observational studies of COVID-19 adults admitted to critical care were included. Studies of mixed cohorts and intensive care cohorts restricted to a specific patient sub-group were excluded. Dichotomous variables were reported with pooled OR and 95%CI, and continuous variables with pooled standardised mean difference (SMD) and 95%CI. Fifty-eight studies (44,305 patients) were included in the review. Increasing age (SMD 0.65, 95%CI 0.53–0.77); smoking (OR 1.40, 95%CI 1.03–1.90); hypertension (OR 1.54, 95%CI 1.29–1.85); diabetes (OR 1.41, 95%CI 1.22–1.63); cardiovascular disease (OR 1.91, 95%CI 1.52–2.38); respiratory disease (OR 1.75, 95%CI 1.33–2.31); renal disease (OR 2.39, 95%CI 1.68–3.40); and malignancy (OR 1.81, 95%CI 1.30–2.52) were associated with mortality. A higher sequential organ failure assessment score (SMD 0.86, 95%CI 0.63–1.10) and acute physiology and chronic health evaluation-2 score (SMD 0.89, 95%CI 0.65–1.13); a lower PaO₂:F_IO₂ (SMD −0.44, 95%CI −0.62 to −0.26) and the need for mechanical ventilation at admission (OR 2.53, 95%CI 1.90–3.37) were associated with mortality. Higher white cell counts (SMD 0.37, 95%CI 0.22–0.51); neutrophils (SMD 0.42, 95%CI 0.19–0.64); D-dimers (SMD 0.56, 95%CI 0.43–0.69); ferritin (SMD 0.32, 95%CI 0.19–0.45); lower platelet (SMD −0.22, 95%CI −0.35 to −0.10); and lymphocyte counts (SMD −0.37, 95%CI −0.54 to −0.19) were all associated with mortality. In conclusion, increasing age, pre-existing comorbidities, severity of illness based on validated scoring systems, and the host response to the disease were associated with mortality; while male sex and increasing BMI were not. These factors have prognostic relevance for patients admitted to intensive care with COVID-19.     

The impact of COVID-19 on anaesthesia and critical care services in the UK: a serial service evaluation*

Between October 2020 and January 2021, we conducted three national surveys to track anaesthetic, surgical and critical care activity during the second COVID-19 pandemic wave in the UK. We surveyed all NHS hospitals where surgery is undertaken. Response rates, by round, were 64%, 56% and 51%. Despite important regional variations, the surveys showed increasing systemic pressure on anaesthetic and peri-operative services due to the need to support critical care pandemic demands. During Rounds 1 and 2, approximately one in eight anaesthetic staff were not available for anaesthetic work. Approximately one in five operating theatres were closed and activity fell in those that were open. Some mitigation was achieved by relocation of surgical activity to other locations. Approximately one-quarter of all surgical activity was lost, with paediatric and non-cancer surgery most impacted. During January 2021, the system was largely overwhelmed. Almost one-third of anaesthesia staff were unavailable, 42% of operating theatres were closed, national surgical activity reduced to less than half, including reduced cancer and emergency surgery. Redeployed anaesthesia staff increased the critical care workforce by 125%. Three-quarters of critical care units were so expanded that planned surgery could not be safely resumed. At all times, the greatest resource limitation was staff. Due to lower response rates from the most pressed regions and hospitals, these results may underestimate the true impact. These findings have important implications for understanding what has happened during the COVID-19 pandemic, planning recovery and building a system that will better respond to future waves or new epidemics.     

Consensus guidelines for managing the airway in patients with COVID-19

Severe acute respiratory syndrome-corona virus-2, which causes coronavirus disease 2019 (COVID-19), is highly contagious. Airway management of patients with COVID-19 is high risk to staff and patients. We aimed to develop principles for airway management of patients with COVID-19 to encourage safe, accurate and swift performance. This consensus statement has been brought together at short notice to advise on airway management for patients with COVID-19, drawing on published literature and immediately available information from clinicians and experts. Recommendations on the prevention of contamination of healthcare workers, the choice of staff involved in airway management, the training required and the selection of equipment are discussed. The fundamental principles of airway management in these settings are described for: emergency tracheal intubation; predicted or unexpected difficult tracheal intubation; cardiac arrest; anaesthetic care; and tracheal extubation. We provide figures to support clinicians in safe airway management of patients with COVID-19. The advice in this document is designed to be adapted in line with local workplace policies.     

Protracted COVID-19 pneumonitis early post-ABO incompatible kidney transplantation: Management considerations and the role of whole genome sequencing

We present the case of a recent ABO incompatible kidney transplant recipient with persistent SARS-CoV-2 infection and pneumonitis. Serial whole genome sequencing confirmed intra-host viral evolution, which was used as a surrogate to confirm active viral replication and support re-treatment with antivirals, late in the course of infection. A prolonged course of remdesivir combined with immunosuppression modulation resulted in successful clearance of virus and clinical improvement. The diagnostic process undertaken in this case provides a useful guide for other clinicians when approaching similar patients.     

Effect of the COVID-19 pandemic on bariatric surgery in North America: a retrospective analysis of 834,647 patients

BackgroundCOVID-19 has transformed surgical care, yet little is known regarding implications for bariatric surgery.ObjectiveWe sought to characterize the effect of COVID-19 on bariatric surgery delivery and outcomes.SettingThe Metabolic and Bariatric Accreditation and Quality Improvement Program (MBSAQIP) collects data from 885 centers in North America.MethodsThe MBSAQIP database was evaluated with 2 cohorts described: the COVID-19 and the pre–COVID-19, with patients receiving surgery in 2020 and 2015–2019, respectively. Yearly operative trends were characterized, and bivariate analysis compared demographics and postoperative outcomes. Multivariable modeling evaluated 30-day readmission, reintervention, and reoperation rates and factors associated with undergoing Roux-en-Y gastric bypass.ResultsWe evaluated 834,647 patients, with 155,830 undergoing bariatric surgery during the 2020 pandemic year. A 12.1% reduction in total cases (177,208 in 2019 versus 155,830 in 2020; P < .001) and 13.8% reduction in cases per center occurred (204.2 cases per center in 2019 versus 176.1 cases per center in 2020; P < .001). Patients receiving bariatric surgery during the pandemic were younger and had fewer co-morbidities. Use of sleeve gastrectomy increased (74.5% versus 72.5%; P < .001), and surgery during COVID-19 was associated with reduced Roux-en-Y gastric bypass procedure selection (odds ratio = .83; 95% CI: .82–.84; P < .001). Length of stay decreased significantly (1.4 ± 1.4 days versus 1.6 ± 1.4 days; P < .001), yet postoperative outcomes were similar. After adjusting for co-morbidities, patients during COVID-19 had decreased 30-day odds of readmission and reintervention and a small increase in odds of reoperation.ConclusionThe COVID-19 pandemic dramatically changed bariatric surgery delivery. Further studies evaluating the long-term effects of these changes are warranted.     

Cardiovascular subphenotypes in patients with COVID-19 pneumonitis whose lungs are mechanically ventilated: a single-centre retrospective observational study

Unsupervised clustering methods of transthoracic echocardiography variables have not been used to characterise circulatory failure mechanisms in patients with COVID-19 pneumonitis. We conducted a retrospective, single-centre cohort study in ICU patients with COVID-19 pneumonitis whose lungs were mechanically ventilated and who underwent transthoracic echocardiography between March 2020 and May 2021. We performed latent class analysis of echocardiographic and haemodynamic variables. We characterised the identified subphenotypes by comparing their clinical parameters, treatment responses and 90-day mortality rates. We included 305 patients with a median (IQR [range]) age 59 (49–66 [16–83]) y. Of these, 219 (72%) were male, 199 (65%) had moderate acute respiratory distress syndrome and 113 (37%) did not survive more than 90 days. Latent class analysis identified three cardiovascular subphenotypes: class 1 (52%; normal right ventricular function); class 2 (31%; right ventricular dilation with mostly preserved systolic function); and class 3 (17%; right ventricular dilation with systolic impairment). The three subphenotypes differed in their clinical characteristics and response to prone ventilation and outcomes, with 90-day mortality rates of 22%, 42% and 73%, respectively (p < 0.001). We conclude that the identified subphenotypes aligned with right ventricular pathophysiology rather than the accepted definitions of right ventricular dysfunction, and these identified classifications were associated with clinical outcomes.     

Outcomes of critically ill patients with acute kidney injury in COVID-19 infection: an observational study

BackgroundEarly reports indicate that AKI is common during COVID-19 infection. Different mortality rates of AKI due to SARS-CoV-2 have been reported, based on the degree of organic dysfunction and varying from public to private hospitals. However, there is a lack of data about AKI among critically ill patients with COVID-19.MethodsWe conducted a multicenter cohort study of 424 critically ill adults with severe acute respiratory syndrome (SARS) and AKI, both associated with SARS-CoV-2, admitted to six public ICUs in Brazil. We used multivariable logistic regression to identify risk factors for AKI severity and in-hospital mortality.ResultsThe average age was 66.42 ± 13.79 years, 90.3% were on mechanical ventilation (MV), 76.6% were at KDIGO stage 3, and 79% underwent hemodialysis. The overall mortality was 90.1%. We found a higher frequency of dialysis (82.7% versus 45.2%), MV (95% versus 47.6%), vasopressors (81.2% versus 35.7%) (p < 0.001) and severe AKI (79.3% versus 52.4%; p = 0.002) in nonsurvivors. MV, vasopressors, dialysis, sepsis-associated AKI, and death (p < 0.001) were more frequent in KDIGO 3. Logistic regression for death demonstrated an association with MV (OR = 8.44; CI 3.43–20.74) and vasopressors (OR = 2.93; CI 1.28–6.71; p < 0.001). Severe AKI and dialysis need were not independent risk factors for death. MV (OR = 2.60; CI 1.23–5.45) and vasopressors (OR = 1.95; CI 1.12–3.99) were also independent risk factors for KDIGO 3 (p < 0.001).ConclusionCritically ill patients with SARS and AKI due to COVID-19 had high mortality in this cohort. Mortality was largely determined by the need for mechanical ventilation and vasopressors rather than AKI severity.     

Outcomes from intensive care in patients with COVID-19: a systematic review and meta-analysis of observational studies

The emergence of coronavirus disease 2019 (COVID-19) has led to high demand for intensive care services worldwide. However, the mortality of patients admitted to the intensive care unit (ICU) with COVID-19 is unclear. Here, we perform a systematic review and meta-analysis, in line with PRISMA guidelines, to assess the reported ICU mortality for patients with confirmed COVID-19. We searched MEDLINE, EMBASE, PubMed and Cochrane databases up to 31 May 2020 for studies reporting ICU mortality for adult patients admitted with COVID-19. The primary outcome measure was death in intensive care as a proportion of completed ICU admissions, either through discharge from the ICU or death. The definition thus did not include patients still alive on ICU. Twenty-four observational studies including 10,150 patients were identified from centres across Asia, Europe and North America. In-ICU mortality in reported studies ranged from 0 to 84.6%. Seven studies reported outcome data for all patients. In the remaining studies, the proportion of patients discharged from ICU at the point of reporting varied from 24.5 to 97.2%. In patients with completed ICU admissions with COVID-19 infection, combined ICU mortality (95%CI) was 41.6% (34.0–49.7%), I² = 93.2%). Sub-group analysis by continent showed that mortality is broadly consistent across the globe. As the pandemic has progressed, the reported mortality rates have fallen from above 50% to close to 40%. The in-ICU mortality from COVID-19 is higher than usually seen in ICU admissions with other viral pneumonias. Importantly, the mortality from completed episodes of ICU differs considerably from the crude mortality rates in some early reports.     

Battling COVID-19: critical care and peri-operative healthcare resource management strategies in a tertiary academic medical centre in Singapore

In December 2019, a cluster of atypical pneumonia cases were reported in Wuhan, China, and a novel coronavirus elucidated as the aetiologic agent. Although most initial cases occurred in China, the disease, termed coronavirus disease 2019, has become a pandemic and continues to spread rapidly with human-to-human transmission in many countries. This is the third novel coronavirus outbreak in the last two decades and presents an ensuing healthcare resource burden that threatens to overwhelm available healthcare resources. A study of the initial Chinese response has shown that there is a significant positive association between coronavirus disease 2019 mortality and healthcare resource burden. Based on the Chinese experience, some 19% of coronavirus disease 2019 cases develop severe or critical disease. This results in a need for adequate preparation and mobilisation of critical care resources to anticipate and adapt to a surge in coronavirus disease 2019 case-load in order to mitigate morbidity and mortality. In this article, we discuss some of the peri-operative and critical care resource planning considerations and management strategies employed in a tertiary academic medical centre in Singapore in response to the coronavirus disease 2019 outbreak.     

The effect of COVID-19 on surgical training

The COVID-19 pandemic has had a huge impact on society, healthcare in general and also on training in surgery. Cancellation of elective procedures, redeployment and establishment of green sites have combined with other factors to create significant gaps in training experience in operative and all other areas of surgery. There are nearly a million cases which have been lost to training since March 2020 and recovery means that tens of thousands of extra training cases have to be performed every month to recover that experience. There are pressures to address huge waiting list backlogs which may squeeze out time for training unless training is considered at the heart of any recovery plan. #NoTrainingTodayNoSurgeonsTomorrow. New, no blame, COVID ARCP outcomes have helped recognize the impact of the pandemic on progression and significant trainee and trainer organizations are united in raising the profile of the training crisis and offering a suite of suggestions on how to speed recovery. Disruption caused by the pandemic has allowed existing simulation and conferencing platforms to finally be widely accepted and the importance of the wider surgical team in supporting surgical training to be realized. New, outcomes-based curricula, with better feedback at their centre, will speed recovery of training trajectories. We should embrace the opportunity for change to help short and medium term recovery and improve the delivery of surgical training into the future.     

中低剂量糖皮质激素影响新型冠状病毒清除时间的回顾性研究

目的研究中低剂量糖皮质激素治疗对新型冠状病毒肺炎(COVID-19)患者病毒清除时间的影响。方法回顾性分析2020年1月19日至2月17日浙江大学医学院附属第一医院收治的72例COVID-19患者的临床资料。全部患者均接受阿比多尔和/或联合洛匹那韦/利托那韦、达芦那韦/考比司他抗病毒以及对症支持治疗,其中51例使用甲泼尼龙(0.75~1.50 mg·kg-1·d-1)抗炎治疗作为糖皮质激素治疗组,21例未使用糖皮质激素者作为对照组。比较两组患者及普通型患者痰液病毒核酸转阴时间和肺部影像学改善时间。组间比较采用Kruskal-Wallis检验或Fisher精确检验。结果糖皮质激素治疗组与对照组中位年龄分别为52(45,62)和46(32,56)岁,两组比较差异有统计学意义(χ2=4.365,P<0.05)。两组临床分型差异有统计学意义(P<0.01),糖皮质激素治疗组中重型患者占52.0%,而对照组中普通型占71.4%。两组患者从发病至痰液病毒核酸转阴中位时间分别为15(13,20)和14(12,20)d,差异无统计学意义(P>0.05);两组患者从发病至肺部影像学好转中位时间分别为13(11,15)和13(12,17)d,差异无统计学意义(P>0.05)。在普通型患者中,糖皮质激素治疗组与对照组从发病至痰液病毒核酸转阴中位时间为13(11,18)和13(12,15)d,差异无统计学意义(P>0.05);从发病至肺影像学好转中位时间分别为12(10,15)和13(12,17)d,差异也无统计学意义(P>0.05)。结论在不同临床类型的COVID-19患者中,中低剂量糖皮质激素使用对病毒清除时间未见明显影响;普通型患者中未观察到激素可以加快肺损伤的改善,故不建议使用。     

Right ventricular dysfunction in patients with COVID-19 pneumonitis whose lungs are mechanically ventilated: a multicentre prospective cohort study

Cardiovascular complications due to COVID-19, such as right ventricular dysfunction, are common. The combination of acute respiratory distress syndrome, invasive mechanical ventilation, thromboembolic disease and direct myocardial injury creates conditions where right ventricular dysfunction is likely to occur. We undertook a prospective, multicentre cohort study in 10 Scottish intensive care units of patients with COVID-19 pneumonitis whose lungs were mechanically ventilated. Right ventricular dysfunction was defined as the presence of severe right ventricular dilation and interventricular septal flattening. To explore the role of myocardial injury, high-sensitivity troponin and N-terminal pro B-type natriuretic peptide plasma levels were measured in all patients. We recruited 121 patients and 118 (98%) underwent imaging. It was possible to determine the primary outcome in 112 (91%). Severe right ventricular dilation was present in 31 (28%), with interventricular septal flattening present in nine (8%). Right ventricular dysfunction (the combination of these two parameters) was present in seven (6%, 95%CI 3–13%). Thirty-day mortality was 86% in those with right ventricular dysfunction as compared with 45% in those without (p = 0.051). Patients with right ventricular dysfunction were more likely to have: pulmonary thromboembolism (p < 0.001); higher plateau airway pressure (p = 0.048); lower dynamic compliance (p = 0.031); higher plasma N-terminal pro B-type natriuretic peptide levels (p = 0.006); and raised plasma troponin levels (p = 0.048). Our results demonstrate a prevalence of right ventricular dysfunction of 6%, which was associated with increased mortality (86%). Associations were also observed between right ventricular dysfunction and aetiological domains of: acute respiratory distress syndrome; ventilation; thromboembolic disease; and direct myocardial injury, implying a complex multifactorial pathophysiology.     

Renal impairment and its impact on clinical outcomes in patients who are critically ill with COVID-19: a multicentre observational study

Renal impairment is common in patients who are critically ill with coronavirus disease-19 (COVID-19). We examined the association between acute and chronic kidney disease with clinical outcomes in 372 patients with coronavirus disease-19 admitted to four regional intensive care units between 10 March 2020 and 31 July 2020. A total of 216 (58%) patients presented with COVID-19 and renal impairment. Acute kidney injury and/or chronic kidney disease was associated with greater in-hospital mortality compared with patients with preserved renal function (107/216 patients (50%) (95%CI 44–57) vs. 32/156 (21%) (95%CI 15–28), respectively; p < 0.001, relative risk 2.4 (95%CI 1.7–3.4)). Mortality was greatest in patients with renal transplants (6/7 patients (86%) (95%CI 47–100)). Mortality rates increased in patients with worsening renal injury according to the Kidney Disease: Improving Global Outcomes classification: stage 0 mortality 33/157 patients (21%) (95%CI 15–28) vs. stages 1–3 mortality 91/186 patients (49%) (95%CI 42–56); p < 0.001, relative risk 2.3 (95%CI 1.7–3.3). Survivors were less likely to require renal replacement therapy compared with non-survivors (57/233 patients (24%) vs. 64/139 patients (46%), respectively; p < 0.001, relative risk 1.9 (95%CI 1.4–2.5)). One-fifth of survivors who required renal replacement therapy acutely in intensive care continued to require renal support following discharge. Our data demonstrate that renal impairment in patients admitted to intensive care with COVID-19 is common and is associated with a high mortality and requirement for on-going renal support after discharge from critical care. Our findings have important implications for future pandemic planning in this patient cohort.     

密切接触疑似新型冠状病毒感染患者的一例断指再植手术的处理

2019年12月以来,新型冠状病毒肺炎(COVID-19)在中国武汉出现.我院在2020年1月下旬,为1例接触疑似新型冠状病毒肺炎的断指患者实行再植手术,获得成功.     

The Royal College of surgeons multidisciplinary guidelines on elective tracheostomy insertion in COVID-19 ventilated patients

BackgroundThe current COVID-19 pandemic has placed enormous strain on healthcare systems worldwide. Understanding of COVID-19 is rapidly evolving. Pneumonia associated with COVID-19 may lead to respiratory failure requiring mechanical ventilation. The rise in patients requiring mechanical ventilation may lead to an increase in tracheostomies being performed in patients with COVID-19. Performing tracheostomy in patients with active SARS-CoV-2 infection poses a number of challenges.MethodsThese guidelines were written following multidisciplinary agreement between Otolaryngology, Head and Neck Surgery, Respiratory Medicine and the Department of Anaesthetics and Critical Care Medicine in the Royal College of Surgeons in Ireland. A literature review was performed and a guideline for elective tracheostomy insertion in patients with COVID-19 proposed.ConclusionThe decision to perform tracheostomy in patients with COVID-19 should be undertaken by senior members of the multidisciplinary team. Steps should be taken to minimise risks to healthcare workers.