Cardiovascular Adaptation in Fetal Growth Restriction: A Longitudinal Study From Fetuses at Term to the First Year of Life.

OBJECTIVE: To investigate longitudinal trends in fetal and offspring cardiovascular adaptation in fetal growth restriction (FGR). DESIGN: Prospective longitudinal study. SETTING: Fetal Medicine Unit. SAMPLE: Thirty-five FGR pregnancies and 37 healthy controls assessed as term fetuses (mean age 37 ± 1 weeks) and again in infancy (mean age 8 ± 2 months). METHODS: Conventional echocardiographic techniques, tissue Doppler imaging and speckle tracking echocardiography. MAIN OUTCOME MEASURES: Left ventricular (LV) and right ventricular (RV) geometry and function. Echocardiographic parameters were normalised by ventricular size adjusting for differences in body weight between groups. RESULTS: Compared to healthy controls, late FGR fetuses showed significant alterations in cardiac geometry with more globular LV chamber (LV sphericity index, 0.56 vs. 0.52), increase in biventricular global longitudinal systolic contractility (MAPSE, 0.29 vs. 0.25 mm; TAPSE, 0.42 vs. 0.37 mm) and elevated cardiac output (combined CO: 592 vs. 497 mL/min/kg, p < 0.01 for all). Indices of LV diastolic function in FGR fetuses were significantly impaired with myocardial diastolic velocities (LV A', 0.30 vs. 0.26 cm/s; IVS E', 0.19 vs. 0.16 cm/s) and LV torsion (1.2 vs. 3.5 deg./cm, p < 0.01 for all). At postnatal assessment, FGR offspring revealed persistently increased SAPSE (0.27 vs. 0.24 mm), LV longitudinal strain (-19.0 vs. -16.0%), reduced LV torsion (1.6 vs. 2.1 deg./cm) and elevated CO (791 vs. 574 mL/min/kg, p < 0.01 for all). CONCLUSIONS: Perinatal cardiac remodelling and myocardial dysfunction in late FGR fetuses is most likely due to chronic placental hypoxaemia. Persistent changes in cardiac geometry and function in FGR offspring may reflect fetal cardiovascular maladaptation that could predispose to long-term cardiovascular complications in later life.

Rethinking ketamine as a panacea: adverse effects on oxygenation and postoperative outcomes.

Ketamine is receiving renewed interest in perioperative medicine as an anaesthetic adjunct and a treatment for chronic conditions, including depression. Ketamine's complex pharmacologic profile results not only in several desirable effects, such as anaesthesia and analgesia, but also multiple adverse effects affecting the central nervous, cardiovascular, and respiratory systems. In addition to defining patient-centred outcomes in future clinical studies on the perioperative uses of ketamine, careful monitoring for its numerous adverse effects will be paramount.

Association of ketamine use during procedural sedation with oxygen desaturation and healthcare utilisation: a multicentre retrospective hospital registry study.

BACKGROUND: We investigated the effects of ketamine on desaturation and the risk of nursing home discharge in patients undergoing procedural sedation by anaesthetists. METHODS: We included adult patients who underwent procedures under monitored anaesthetic care between 2005 and 2021 at two academic healthcare networks in the USA. The primary outcome was intraprocedural oxygen desaturation, defined as oxygen saturation <90% for ≥2 consecutive minutes. The co-primary outcome was a nursing home discharge. RESULTS: Among 234,170 included patients undergoing procedural sedation, intraprocedural desaturation occurred in 5.6% of patients who received ketamine vs 5.2% of patients who did not receive ketamine (adjusted odds ratio [ORadj] 1.22, 95% confidence interval [CI] 1.15-1.29, P<0.001; adjusted absolute risk difference [ARDadj] 1%, 95% CI 0.7-1.3%, P<0.001). The effect was magnified by age >65 yr, smoking, or preprocedural ICU admission (P-for-interaction <0.001, ORadj 1.35, 95% CI 1.25-1.45, P<0.001; ARDadj 2%, 95% CI 1.56-2.49%, P<0.001), procedural risk factors (upper endoscopy of longer than 2 h; P-for-interaction <0.001, ORadj 2.91, 95% CI 1.85-4.58, P<0.001; ARDadj 16.2%, 95% CI 9.8-22.5%, P<0.001), and high ketamine dose (P-for-trend <0.001, ORadj 1.61, 95% CI, 1.43-1.81 for ketamine >0.5 mg kg-1). Concomitant opioid administration mitigated the risk (P-for-interaction <0.001). Ketamine was associated with higher odds of nursing home discharge (ORadj 1.11, 95% CI 1.02-1.21, P=0.012; ARDadj 0.25%, 95% CI 0.05-0.46%, P=0.014). CONCLUSIONS: Ketamine use for procedural sedation was associated with an increased risk of oxygen desaturation and discharge to a nursing home. The effect was dose-dependent and magnified in subgroups of vulnerable patients.

Effect of skin tone on the accuracy of the estimation of arterial oxygen saturation by pulse oximetry: a systematic review.

BACKGROUND: Pulse oximetry-derived oxygen saturation (SpO2) is an estimate of true arterial oxygen saturation (SaO2). The aim of this review was to evaluate available evidence determining the effect of skin tone on the ability of pulse oximeters to accurately estimate SaO2. METHODS: Published literature was screened to identify clinical and non-clinical studies enrolling adults and children when SpO2 was compared with a paired co-oximetry SaO2 value. We searched literature databases from their inception to March 20, 2023. Risk of bias (RoB) was assessed using the QUADAS-2 tool. Certainty of assessment was evaluated using the GRADE tool. RESULTS: Forty-four studies were selected reporting on at least 222 644 participants (6121 of whom were children) and 733 722 paired SpO2-SaO2 measurements. Methodologies included laboratory studies, prospective clinical, and retrospective clinical studies. A high RoB was detected in 64% of studies and there was considerable heterogeneity in study design, data analysis, and reporting metrics. Only 11 (25%) studies measured skin tone in 2353 (1.1%) participants; the remainder reported participant ethnicity: 68 930 (31.0%) participants were of non-White ethnicity or had non-light skin tones. The majority of studies reported overestimation of SaO2 by pulse oximetry in participants with darker skin tones or from ethnicities assumed to have darker skin tones. Several studies reported no inaccuracy related to skin tone. Meta-analysis of the data was not possible. CONCLUSIONS: Pulse oximetry can overestimate true SaO2 in people with darker skin tones. The clinical relevance of this bias remains unclear, but its magnitude is likely to be greater when SaO2 is lower. SYSTEMATIC REVIEW PROTOCOL: International Prospective Register of Systematic Reviews (PROSPERO): CRD42023390723.

Thoracic Society of Australia and New Zealand clinical practice guideline on adult home oxygen therapy.

This Thoracic Society of Australia and New Zealand Guideline on the provision of home oxygen therapy in adults updates a previous Guideline from 2015. The Guideline is based upon a systematic review and meta-analysis of literature to September 2022 and the strength of recommendations is based on GRADE methodology. Long-term oxygen therapy (LTOT) is recommended for its mortality benefit for patients with COPD and other chronic respiratory diseases who have consistent evidence of significant hypoxaemia at rest (PaO2 ≤ 55 mm Hg or PaO2 ≤59 mm Hg in the presence of hypoxaemic sequalae) while in a stable state. Evidence does not support the use of LTOT for patients with COPD who have moderate hypoxaemia or isolated nocturnal hypoxaemia. In the absence of hypoxaemia, there is no evidence that oxygen provides greater palliation of breathlessness than air. Evidence does not support the use of supplemental oxygen therapy during pulmonary rehabilitation in those with COPD and exertional desaturation but normal resting arterial blood gases. Both positive and negative effects of LTOT have been described, including on quality of life. Education about how and when to use oxygen therapy in order to maximize its benefits, including the use of different delivery devices, expectations and limitations of therapy and information about hazards and risks associated with its use are key when embarking upon this treatment.

Sinus venosus atrial septal defect presenting with platypnea-orthodeoxia syndrome in the setting of COVID-19 infection.

Platypnea-orthodeoxia syndrome is characterised by hypoxemia and dyspnoea while upright that resolves when supine, typically associated with an interatrial communication. We present a case of platypnea-orthodeoxia syndrome associated with a sinus venosus atrial septal defect in a patient with multiple possible aetiologies of hypoxemia, including COVID-19 infection. Cardiac catheterisation with provocative maneuvers confirmed the diagnosis and symptoms resolved following defect closure. We suggest that in patients with platypnea-orthodeoxia syndrome, it is useful to obtain haemodynamic data while supine and upright.

The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses.

OBJECTIVE: To investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses. STUDY DESIGN: Retrospective, single-centre study. ANIMALS: A sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021. METHODS: Horses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recoveries were divided into 'good' and 'bad' based on the available recovery scores. Influence of hypoxaemia [PaO2 < 60 mmHg (7.99 kPa)], hypotension (mean arterial pressure < 70 mmHg for at least 15 minutes) and hypercapnia [PaCO2 > 60 mmHg (7.99 kPa)], anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of procedure, emergency or nonemergency, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery on the assigned recovery score (good/bad) were investigated using generalized linear regression analysis (p < 0.05). RESULTS: Hypoxaemia and prolonged duration of anaesthesia were significantly associated with a bad recovery score. No other factors had a significant influence on recovery quality. CONCLUSION AND CLINICAL RELEVANCE: Hypoxaemia and prolonged anaesthesia duration have a negative effect on quality of anaesthetic recovery in horses. Clinically, this highlights the importance of keeping anaesthetic time as short as possible and to monitor oxygenation and treat hypoxaemia as soon as possible.

Retrospective study of the changes in dynamic compliance and ventilation/perfusion mismatch following salbutamol inhalation in hypoxaemic mechanically ventilated anaesthetized horses.

OBJECTIVE: To study the changes in dynamic compliance (Cdyn), ventilation/perfusion (V˙/ Q˙) mismatch and haemodynamic variables in hypoxaemic anaesthetized horses whose PaO2 increased following salbutamol inhalation. STUDY DESIGN: Retrospective, clinical, cohort study. ANIMALS: A group of 73 client-owned horses treated with salbutamol when PaO2 <100 mmHg (13.3 kPa) during anaesthesia. METHODS: Horses were divided into two groups: responders (R), where PaO2 after salbutamol ≥1.2 PaO2 before treatment (i.e. ≥20% increase), and non-responders (NR), where PaO2 after salbutamol <1.2 PaO2 before treatment. Demographic data and intraoperative variables before treatment were compared between R and NR. Cdyn, arterial to end-tidal carbon dioxide difference [P(a-E´)CO2], estimated ratio of dead space to tidal volume (est.VD/VT), estimated shunt fraction (F-shunt), heart rate, systolic, mean and diastolic arterial pressure and dobutamine requirements were compared before and after treatment within R and NR. For each variable, the difference (Δ) between values pre- and posttreatment was calculated and compared between groups R and NR. Numerical data were compared using univariate or bivariate analysis and categorical data were compared using chi-square test; p < 0.05. RESULTS: Of the 73 horses 50 were classified as R while 23 horses were classified as NR. There was no statistical difference between R and NR for demographic data or initial intraoperative variables except for body weight [R: 531 (170-715) kg, NR: 540 (420-914) kg]. While salbutamol did not alter Cdyn in either group, it significantly decreased P(a-E´)CO2, est.VD/VT and F-shunt in R only. ΔP(a-E´)CO2, Δest.VD/VT and ΔF-shunt were significantly greater in R (-17.8%, -19.0% and -24.1%, respectively) than in NR (11.5%, 6.6% and -0.3%, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: In hypoxaemic anaesthetized horses responding to inhaled salbutamol by a ≥1.2 increase in PaO2 no change in Cdyn was detected, but indicators of V˙/ Q˙ mismatch improved.

High preoperative bradykinin level is a risk factor for severe postoperative hypoxaemia in acute aortic dissection surgery.

NEW FINDINGS: What is the central question of this study? Hypoxaemia can lead to increased postoperative mortality in patients: what are the independent risk factors for severe hypoxaemia after acute Stanford type A aortic dissection? What is the main finding and its importance? Severe postoperative hypoxaemia was found in 36.4% of patients, and it was determined that high preoperative bradykinin levels and increased BMI were independent predictors of severe postoperative hypoxaemia in patients with acute Stanford type A aortic dissection. For obese patients with high preoperative bradykinin levels, more attention should be paid to preventing severe postoperative hypoxaemia. ABSTRACT: Severe hypoxaemia after cardiac surgery is associated with serious complications and a high risk of mortality. The purpose of this study is to investigate the independent risk factors of severe postoperative hypoxaemia in patients with acute Stanford type A aortic dissection. We collected 77 patients with acute Stanford type A aortic dissection who underwent surgical treatment. The primary outcome was severe postoperative hypoxaemia (PaO2 /FiO2  ≤ 100 mmHg), and a multivariate logistic regression analysis was performed to assess the independent predictors of risk for this. A mixed-effects analysis of variance model and a receiver operating characteristic (ROC) curve were generated to evaluate the predictive probabilities of risk factors for severe postoperative hypoxaemia. A total of 36.4% of patients developed severe postoperative hypoxaemia. The multivariate logistic regression analysis identified high preoperative bradykinin level (odds ratio (OR) = 55.918, P < 0.001) and increased body mass index (BMI; OR = 1.292, P = 0.032) as independent predictors of severe postoperative hypoxaemia in patients with acute Stanford type A aortic dissection. The mixed-effect analysis of variance model and ROC curve indicated that high preoperative bradykinin level and BMI were significant predictors of severe postoperative hypoxaemia (area under the ROC curve = 0.834 and 0.764, respectively). High preoperative bradykinin levels and obesity were independent risk factors for severe postoperative hypoxaemia in patients with acute Stanford type A aortic dissection. For obese patients with high levels of bradykinin before surgery, clinicians should actively take measures to block bradykinin-mediated inflammatory reactions.

Obstructive sleep apnea-related intermittent hypoxaemia is associated with impaired vigilance.

Obstructive sleep apnea (OSA)-related intermittent hypoxaemia is a potential risk factor for different OSA comorbidities, for example cardiovascular disease. However, conflicting results are found as to whether intermittent hypoxaemia is associated with impaired vigilance. Therefore, we aimed to investigate how desaturation characteristics differ between the non-impaired vigilance and impaired vigilance patient groups formed based on psychomotor vigilance task (PVT) performance and compared with traditional OSA severity parameters. The study population comprised 863 patients with suspected OSA who underwent a PVT test before polysomnography. The conventional OSA parameters, for example, the apnea-hypopnea index, oxygen desaturation index, and arousal index were computed. Furthermore, the median desaturation area, fall area, recovery area, and desaturation depth were computed with the pre-event baseline reference and with reference to the 100% oxygen saturation level. Patients were grouped into best- and worst-performing quartiles based on the number of lapses in PVT (Q1: PVT lapses <5 and Q4: PVT lapses >36). The association between parameters and impaired vigilance was evaluated by cumulative distribution functions (CDFs) and binomial logistic regression. Based on the CDFs, patients in Q4 had larger desaturation areas, recovery areas, and deeper desaturations when these were referenced to 100% saturation compared with Q1. The odds ratio (OR) of the median desaturation area (OR = 1.56), recovery area (OR = 1.71), and depth (OR = 1.65) were significantly elevated in Q4 in regression models. However, conventional OSA parameters were not significantly associated with impaired vigilance (ORs: 0.79-1.09). Considering desaturation parameters with a 100% SpO2 reference in the diagnosis of OSA could provide additional information on the severity of OSA and related daytime vigilance impairment.

Effect of a pre-emptive 2-hour session of high-flow nasal oxygen on postoperative oxygenation after major gynaecologic surgery: a randomised clinical trial.

BACKGROUND: We aimed at determining whether a 2-h session of high-flow nasal oxygen (HFNO) immediately after extubation improves oxygen exchange after major gynaecological surgery in the Trendelenburg position in adult female patients. METHODS: In this single-centre, open-label, randomised trial, patients who underwent major gynaecological surgery were randomised to HFNO or conventional oxygen treatment with a Venturi mask. The primary outcome was the Pao2/FiO2 ratio after 2 h of treatment. Secondary outcomes included lung ultrasound score, diaphragm thickening fraction, dyspnoea, ventilatory frequency, Paco2, the percentage of patients with impaired gas exchange (Pao2/FiO2 ≤40 kPa) after 2 h of treatment, and postoperative pulmonary complications at 30 days. RESULTS: A total of 83 patients were included (42 in the HFNO group and 41 in the conventional treatment group). After 2 h of treatment, median (inter-quartile range) Pao2/FiO2 was 52.9 (47.9-65.2) kPa in the HFNO group and 45.7 (36.4 -55.9) kPa in the conventional treatment group (mean difference 8.7 kPa [95% CI: 3.4 to 13.9], P=0.003). The lung ultrasound score was lower in the HFNO group than in the conventional treatment group (9 [6-10] vs 12 [10-14], P<0.001), mostly because of the difference of the score in dorsal areas (7 [6-8] vs 10 [9-10], P<0.001). The percentage of patients with impaired gas exchange was lower in the HFNO group than in the conventional treatment group (5% vs 37%, P<0.001). All other secondary outcomes were not different between groups. CONCLUSIONS: In patients who underwent major gynaecological surgery, a pre-emptive 2-h session of HFNO after extubation improved postoperative oxygen exchange and reduced atelectasis compared with a conventional oxygen treatment strategy. CLINICAL TRIAL REGISTRATION: NCT04566419.

Dose-dependent relationship between intra-procedural hypoxaemia or hypocapnia and postoperative delirium in older patients.

BACKGROUND: Previous studies indicated an association between impaired cerebral perfusion and post-procedural neurological disorders. We investigated whether intra-procedural hypoxaemia or hypocapnia are associated with delirium after surgery. METHODS: Inpatients ≥60 yr of age undergoing anaesthesia for surgical or interventional procedures between 2009 and 2020 at an academic healthcare network in the USA (Massachusetts) were included in this hospital registry study. The primary exposure was intra-procedural hypoxaemia, defined as peripheral oxygen saturation <90% for >2 cohering min. The co-primary exposure was hypocapnia during general anaesthesia, defined as end-tidal carbon dioxide pressure ≤25 mm Hg for >5 cohering min. The primary outcome was delirium within 7 days after surgery. RESULTS: Of 71 717 included patients, 1702 (2.4%) developed postoperative delirium, and hypoxaemia was detected in 2532 (3.5%). Of 42 894 patients undergoing general anaesthesia, 532 (1.2%) experienced hypocapnia. The occurrence of either hypoxaemia (adjusted odds ratio [ORadj]=1.71; 95% confidence interval [CI], 1.40-2.07; P<0.001) or hypocapnia (ORadj=1.77; 95% CI, 1.30-2.41; P<0.001) was associated with a higher risk of delirium within 7 days. Both associations were dependent on the magnitude, and increased with event duration (ORadj=1.03; 95% CI, 1.02-1.04; P<0.001 and ORadj=1.01; 95% CI, 1.00-1.01; P=0.005, for each minute increase in the longest continuous episode, respectively). There was no association between occurrence of hypercapnia and postoperative delirium (ORadj=1.24; 95% CI, 0.90-1.71; P=0.181). CONCLUSIONS: Intra-procedural hypoxaemia and hypocapnia were dose-dependently associated with a higher risk of postoperative delirium. These findings support maintaining normal gas exchange to avoid postoperative neurological disorders.

Consensus guidelines for the perioperative management of patients undergoing endoscopic retrograde cholangiopancreatography.

Deep sedation without tracheal intubation (monitored anaesthesia care) and general anaesthesia with tracheal intubation are commonly used anaesthesia techniques for endoscopic retrograde cholangiopancreatography (ERCP). There are distinct pathophysiological differences between monitored anaesthesia care and general anaesthesia that need to be considered depending on the nature and severity of the patient's underlying disease, comorbidities, and procedural risks. An international group of expert anaesthesiologists and gastroenterologists created clinically relevant questions regarding the merits and risks of monitored anaesthesia care vs general anaesthesia in specific clinical scenarios for planning optimal anaesthetic approaches for ERCP. Using a modified Delphi approach, the group created practical recommendations for anaesthesiologists, with the aim of reducing the incidence of perioperative adverse outcomes while maximising healthcare resource utilisation. In the majority of clinical scenarios analysed, our expert recommendations favour monitored anaesthesia care over general anaesthesia. Patients with increased risk of pulmonary aspiration and those undergoing prolonged procedures of high complexity were thought to benefit from general anaesthesia with tracheal intubation. Patient age and ASA physical status were not considered to be factors for choosing between monitored anaesthesia care and general anaesthesia. Monitored anaesthesia care is the favoured anaesthesia plan for ERCP. An individual risk-benefit analysis that takes into account provider and institutional experience, patient comorbidities, and procedural risks is also needed.

Improving pulse oximetry accuracy in dark-skinned patients: technical aspects and current regulations.

Recent concerns regarding the clinical accuracy of pulse oximetry in dark-skinned patients, specifically in detecting occult hypoxaemia, have motivated research on this topic and recently reported in this journal. We provide an overview of the technical aspects of the issue, the sources of inaccuracy, and the current regulations and limitations. These insights offer perspectives on how pulse oximetry can be improved to address these potential limitations.

Heterogeneous treatment effects of dexamethasone 12 mg versus 6 mg in patients with COVID-19 and severe hypoxaemia-Post hoc exploratory analyses of the COVID STEROID 2 trial.

BACKGROUND: Corticosteroids improve outcomes in patients with severe COVID-19. In the COVID STEROID 2 randomised clinical trial, we found high probabilities of benefit with dexamethasone 12 versus 6 mg daily. While no statistically significant heterogeneity in treatment effects (HTE) was found in the conventional, dichotomous subgroup analyses, these analyses have limitations, and HTE could still exist. METHODS: We assessed whether HTE was present for days alive without life support and mortality at Day 90 in the trial according to baseline age, weight, number of comorbidities, category of respiratory failure (type of respiratory support system and oxygen requirements) and predicted risk of mortality using an internal prediction model. We used flexible models for continuous variables and logistic regressions for categorical variables without dichotomisation of the baseline variables of interest. HTE was assessed both visually and with p and S values from likelihood ratio tests. RESULTS: There was no strong evidence for substantial HTE on either outcome according to any of the baseline variables assessed with all p values >.37 (and all S values <1.43) in the planned analyses and no convincingly strong visual indications of HTE. CONCLUSIONS: We found no strong evidence for HTE with 12 versus 6 mg dexamethasone daily on days alive without life support or mortality at Day 90 in patients with COVID-19 and severe hypoxaemia, although these results cannot rule out HTE either.

Analysis of an Individualised Stepwise Approach to Non-Pharmacological Therapy in COVID-19.

BACKGROUND: Early intubation versus use of conventional or high-flow nasal cannula oxygen therapy (COT/HFNC), continuous positive airway pressure (CPAP), and non-invasive ventilation (NIV) has been debated throughout the COVID-19 pandemic. Our centre followed a stepwise approach, in concordance with German national guidelines, escalating non-invasive modalities prior to invasive mechanical ventilation (IMV) or extracorporeal membrane oxygenation (ECMO), rather than early or late intubation. OBJECTIVES: The aims of the study were to investigate the real-life usage of these modalities and analyse patient characteristics and survival. METHOD: A retrospective monocentric observation was conducted of all consecutive COVID-19 hospital admissions between March 2020 and December 2021 at a university-affiliated pulmonary centre in Germany. Anthropometric data, therapy, and survival status were descriptively analysed. RESULTS: From 1,052 COVID-19-related admissions, 835 patients were included (54% male, median 58 years). Maximum therapy was as follows: 34% (n = 284) no therapy, 40% (n = 337) COT, 3% (n = 22) HFNC, 9% (n = 73) CPAP, 7% (n = 56) NIV, 4% (n = 34) IMV, and 3% (n = 29) ECMO. Of 551 patients treated with at least COT, 12.3% required intubation. Overall, 183 patients required intensive unit care, and 106 (13%) died. Of the 68 patients who received IMV/ECMO, 48 died (74%). The strategy for non-pharmacological therapy was individual but remained consistent throughout the studied period. CONCLUSIONS: This study provides valuable insight into COVID-19 care in Germany and shows how the majority of patients could be treated with the maximum treatment required according to disease severity following the national algorithm. Escalation of therapy modality is interlinked with disease severity and thus associated with mortality.

Effect of high-flow nasal oxygen on hypoxaemia during procedural sedation: a systematic review and meta-analysis.

We conducted a systematic review to evaluate the effect of high-flow nasal oxygen and conventional oxygen therapy during procedural sedation amongst adults and children. We searched MEDLINE, EMBASE and CINAHL for randomised controlled trials that reported the effects of high-flow nasal oxygen during procedural sedation. The primary outcome measure was hypoxaemia and the secondary outcomes were minimum oxygen saturation; hypercarbia; requirement for airway manoeuvres; and procedure interruptions. The quality of evidence was assessed using the revised Cochrane risk-of bias tool and grading of recommendations, assessment, development and evaluation (GRADE). Nineteen randomised controlled trials (4121 patients) including three in children were included. Administration of high-flow nasal oxygen reduced hypoxaemia, risk ratio (95%CI) 0.37 (0.24-0.56), p < 0.001; minor airway manoeuvre requirements, risk ratio (95%CI) 0.26 (0.11-0.59), p < 0.001; procedural interruptions, risk ratio (95%CI) 0.17 (0.05-0.53), p = 0.002; and increased minimum oxygen saturation, mean difference (95%CI) 4.1 (2.70-5.50), p < 0.001; as compared with the control group. High-flow nasal oxygen had no impact on hypercarbia, risk ratio (95%CI) 1.24 (0.97-1.58), p = 0.09, I2 = 0%. High-flow nasal oxygen reduced the incidence of hypoxaemia regardless of the procedure involved, degree of fractional inspired oxygen, risk-profile of patients and mode of propofol administration. The evidence was ascertained as moderate for all outcomes except for procedure interruptions. In summary, high-flow nasal oxygen compared with conventional oxygenation techniques reduced the risk of hypoxaemia, increased minimum oxygen saturation and reduced the requirement for airway manoeuvres. High-flow nasal oxygen should be considered in patients at risk of hypoxaemia during procedural sedation.

Predictive value of NoSAS questionnaire combined with the modified Mallampati grade for hypoxemia during routine sedation for gastrointestinal endoscopy.

BACKGROUND: The incidence of hypoxemia during painless gastrointestinal endoscopy remains a matter of concem. To date, there is no recognized simple method to predict hypoxemia in digestive endoscopic anesthesia. The NoSAS (neck circumference, obesity, snoring, age, sex) questionnaire, an objective and simple assessment scale used to assess obstructive sleep apnea (OSA), combined with the modified Mallampati grade (MMP), may have certain screening value. This combination may allow anesthesiologists to anticipate, manage, and consequently decrease the occurrence of hypoxemia. METHODS: This study was a prospective observational trial. The primary endpoint was the incidence of hypoxaemia defined as pulse oxygen saturation (SpO2) < 95% for 10 s. A total of 2207 patients admitted to our hospital for painless gastrointestinal endoscopy were studied. All patients were measured for age, height, weight, body mass index, neck circumference, snoring, MMP, and other parameters. Patients were divided into hypoxemic and non-hypoxemic groups based on the SpO2. The ROC curve was plotted to evaluate the screening value of the NoSAS questionnaire separately and combined with MMP for hypoxemia. The total NoSAS score was evaluated at cut-off points of 8 and 9. RESULTS: With a NoSAS score ≥ 8 as the critical value for analysis, the sensitivity for hypoxemia was 58.3%, the specificity was 88.4%, and the area under the ROC was 0.734 (P < 0.001, 95% CI: 0.708-0.759). With a NoSAS score ≥ 9 as a critical value, the sensitivity for hypoxemia was 36.50%, the specificity rose to 96.16%, and the area under the ROC was 0.663 (P < 0.001, 95% CI: 0.639-0.688). With the NoSAS Score combined with MMP for analysis, the sensitivity was 78.4%, the specificity was 84%, and the area under the ROC was 0.859 (P < 0.001, 95%CI:0.834-0.883). CONCLUSIONS: As a new screening tool, the NoSAS questionnaire is simple, convenient, and useful for screening hypoxemia. This questionnaire, when paired withMMP, is likely to be helpful for the screening of hypoxemia.

Exploring the Anti-Hypoxaemia Effect of Hydromethylthionine: A Prospective Study of Phase 3 Clinical Trial Participants.

Methylthioninium chloride (MTC) is a standard treatment for methaemoglobinaemia. A preparation of reduced MTC has been reported to increase blood oxygen saturation (SpO2) and lower respiratory rates in patients with severe COVID-19. We have developed a stable form of reduced methylthionine (hydromethylthionine-mesylate, HMTM) having a benign safety profile in two Phase 3 trials in Alzheimer's disease. The aim of this prospective study was to determine the effects of oral HMTM on SpO2 and methaemoglobin (metHb) levels in a cohort of patients with mild hypoxaemia not due to COVID-19. Eighteen participants randomised to a single dose of 4, 75, 100 or 125 mg doses of HMTM had SpO2 levels below 94% at baseline. Patients were routinely monitored by pulse oximetry after 4 h, and after 2 and 6 weeks of twice daily dosing. Significant ~3% increases in SpO2 occurred within 4 h and were sustained over 2 and 6 weeks with no dose differences. There were small dose-dependent increases (0.060-0.162%) in metHb levels over 2 to 6 weeks. Minimum-energy computational chemistry revealed that HMT can bind within 2.10 Å of heme iron by donating a pair of electrons from the central nitrogen of HMT to d orbitals of heme iron, but with lower affinity than oxygen. In conclusion, HMTM can increase SpO2 without reducing metHb by acting as a strong displaceable field ligand for heme iron. We hypothesise that this facilitates a transition from the low oxygen affinity T-state of heme to the higher affinity R-state. HMTM has potential as an adjunctive treatment for hypoxaemia.

The respiratory system and associated disorders.

Respiratory disease is ubiquitous in hospitals and community healthcare settings in the UK. Nurses, therefore, must be able to understand the physiology and pathophysiology that underpins the care they provide for people living with a respiratory disorder. This article summarises the fundamental anatomy and physiology of the respiratory system and respiration. It also explores the pathophysiological changes that occur in the four most common respiratory conditions, namely pneumonia, lung cancer, asthma and chronic obstructive pulmonary disease. Key elements of a comprehensive respiratory assessment and how nurses can determine acute deterioration are explored. The case study and reflective questions aim to enhance the reader's understanding of respiratory assessment and nursing care.