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.

Changes of Dissociative Properties of Hemoglobin in Patients with Chronic Kidney Disease

Background: The ability of hemoglobin to bind and dissociate oxygen is crucial in delivering oxygen to tissues and is influenced by a range of physiological states, compensatory mechanisms, and pathological conditions. This may be illustrated by the oxyhemoglobin dissociation curve (ODC). The key parameter for evaluating the oxygen affinity to hemoglobin is p50. The aim of this study was to evaluate the impact of hemodialysis on p50 in a group of patients with chronic kidney disease (CKD). An additional goal was to assess the correlation between p50 and the parameters of erythropoiesis, point-of-care testing (POCT), and other laboratory parameters. Methods: One hundred and eighty patients (106 male, 74 female), mean age 62.5 ± 17 years, with CKD stage G4 and G5 were enrolled in this cross-sectional study. Patients were divided into two groups, including 65 hemodialysis (HD) patients and 115 patients not receiving dialysis (non-HD). During the standard procedure of arteriovenous fistula creation, blood samples from the artery (A) and the vein (V) were taken for POCT. The causes of CKD, as well as demographic and comorbidity data, were obtained from medical records and direct interviews. Results: The weekly dose of erythropoietin was higher in HD patients than in non-HD patients (4914 ± 2253 UI vs. 403 ± 798 UI, p < 0.01), but hemoglobin levels did not differ between these groups. In the group of non-HD patients, more advanced metabolic acidosis (MA) was found, compared to the group with HD. In arterial and venosus blood samples, the non-HD group had significantly lower pH, pCO2 and HCO3-. This group had a higher proportion of individuals with MA with HCO3- < 22 mmol/L (42% vs. 24%, p < 0.01). The absolute difference of p50 in arterial and venous blood was determined using the formula Δp50 = (p50-A) - (p50-V). Δp50 was significantly higher in the HD group in comparison to non-HD (0.08 ± 2.05 mmHg vs. -0.66 ± 1.93 mmHg, p = 0,02). There was a negative correlation between pH and the p50 value in arterial (pH-A vs. p50-A, r = -0.56, p < 0.01) and venous blood (pH-V vs. p50-V, r = -0.45, p < 0.01). In non-HD patients, hemoglobin levels correlated negatively with p50 (r = -0.29, p < 0.01), whereas no significant relation was found in HD patients. Conclusions: The ODC in pre-dialysis CKD (non-HD) patients is shifted to the right due to MA, and this is an additional factor influencing erythropoiesis. Hemodialysis restores the natural differences in hemoglobin's dissociation characteristics in the arterial and venous circulation.

Sauerstoff in der Akuttherapie

Sauerstoff (O₂) ist ein Arzneimittel und soll in der Akuttherapie bei Vorliegen einer Hypoxämie ärztlich verordnet und dokumentiert, regelmäßig überwacht und reevaluiert werden. Zur Überwachung dient in der Akutmedizin die Pulsoxymetrie, bei Risikopatienten sind arterielle Blutgase zu bestimmen. Sowohl eine Hypoxämie als auch eine Hyperoxämie sind bei akut Kranken zu vermeiden. Es sollten Zielbereiche der O₂-Sättigung (S_pO₂ [pulsoxymetrisch gemessene O₂-Sättigung]) festgelegt werden. Diese hängen vom Hyperkapnierisiko und vom Beatmungsstatus ab: spontan atmende Patienten ohne bzw. mit Hyperkapnierisiko: Ziel‑S_pO₂ = 92–96 % bzw. 88–92 %, beatmete Patienten: arterielle O₂-Sättigung zwischen 92 und 96 %. Die Zielbereiche gelten bis auf wenige Ausnahmen für alle Erwachsenen unabhängig von der Diagnose. Die O₂-Applikationssysteme werden nach Patientensicherheit und -komfort ausgewählt. Bei Beendigung der O₂-Gabe kann es bei vulnerablen Menschen zur Reboundhypoxämie kommen.

Monitoring Long Term Noninvasive Ventilation: Benefits, Caveats and Perspectives

Long term noninvasive ventilation (LTNIV) is a recognized treatment for chronic hypercapnic respiratory failure (CHRF). COPD, obesity-hypoventilation syndrome, neuromuscular disorders, various restrictive disorders, and patients with sleep-disordered breathing are the major groups concerned. The purpose of this narrative review is to summarize current knowledge in the field of monitoring during home ventilation. LTNIV improves symptoms related to CHRF, diurnal and nocturnal blood gases, survival, and health-related quality of life. Initially, patients with LTNIV were most often followed through elective short in-hospital stays to ensure patient comfort, correction of daytime blood gases and nocturnal oxygenation, and control of nocturnal respiratory events. Because of the widespread use of LTNIV, elective in-hospital monitoring has become logistically problematic, time consuming, and costly. LTNIV devices presently have a built-in software which records compliance, leaks, tidal volume, minute ventilation, cycles triggered and cycled by the patient and provides detailed pressure and flow curves. Although the engineering behind this information is remarkable, the quality and reliability of certain signals may vary. Interpretation of the curves provided requires a certain level of training. Coupling ventilator software with nocturnal pulse oximetry or transcutaneous capnography performed at the patient's home can however provide important information and allow adjustments of ventilator settings thus potentially avoiding hospital admissions. Strategies have been described to combine different tools for optimal detection of an inefficient ventilation. Recent devices also allow adapting certain parameters at a distance (pressure support, expiratory positive airway pressure, back-up respiratory rate), thus allowing progressive changes in these settings for increased patient comfort and tolerance, and reducing the requirement for in-hospital titration. Because we live in a connected world, analyzing large groups of patients through treatment of “big data” will probably improve our knowledge of clinical pathways of our patients, and factors associated with treatment success or failure, adherence and efficacy. This approach provides a useful add-on to randomized controlled studies and allows generating hypotheses for better management of HMV.

Validation of a new combined transcutaneous tcPCO2 and tcPO2 sensor in children in the operating theater

BACKGROUND

Arterial blood gas analysis is the gold standard for monitoring of P_a CO₂ and PaO₂ during mechanical ventilation. However, continuous measurements would be preferred. Transcutaneous sensors continuously measure blood gases diffusing from the locally heated skin. These sensors have been validated in children mostly in intensive care settings. Accuracy in children during general anesthesia is largely unknown.

AIMS

We conducted a study in children undergoing general anesthesia to validate the use and to determine the accuracy of continuous transcutaneous measurements of the partial pressures of PCO₂ (tcPCO₂ ) and PO₂ (tcPO₂ ).

METHODS

A prospective observational study in a tertiary care pediatric hospital in The Netherlands, from April to October 2018, in children aged 0-18 years undergoing general anesthesia. Patients were included when endotracheally intubated and provided with an arterial catheter for regular blood sampling. Patients with a gestational age <31 weeks, burn victims, and patients with skin disease were excluded. TcPCO₂ and tcPO₂  measurements were performed with a SenTec OxiVenT^™ sensor (SenTec AG). Accuracy was determined with an agreement analysis between arterial and transcutaneous PCO₂ and PO₂  values, and between arterial and endtidal PCO₂ (etCO₂ ) values, according to Bland and Altman, accounting for multiple measurements per subject.

RESULTS

We included 53 patients (median age 4.1 years, IQR 0.7-14.4 years) and retrieved 175 samples. TcPCO₂ -P_a CO₂ agreement analysis provided a bias of 0.06 kPa (limits of agreement (LOA) -1.18 to 1.31), the etCO₂ -P_a CO₂ agreement showed a bias of -0.31 kPa (LOA -1.38 to 0.76). Results of the tcPO₂ -PaO₂ agreement showed a bias of 3.40 to 0.86* (mean tension) kPa.

CONCLUSIONS

This study showed good agreement between P_a CO₂ and tcPCO₂ in children of all ages during general anesthesia. Both transcutaneous and endtidal CO₂  measurements showed good accuracy. TcPO₂ is only accurate under 6 months of age.

German S3 Guideline: Oxygen Therapy in the Acute Care of Adult Patients

BACKGROUND

Oxygen (O2) is a drug with specific biochemical and physiological properties, a range of effective doses and may have side effects. In 2015, 14% of over 55,000 hospital patients in the UK were using oxygen. 42% of patients received this supplemental oxygen without a valid prescription. Health care professionals are frequently uncertain about the relevance of hypoxemia and have low awareness about the risks of hyperoxemia. Numerous randomized controlled trials about targets of oxygen therapy have been published in recent years. A national guideline is urgently needed.

METHODS

A national S3 guideline was developed and published within the Program for National Disease Management Guidelines (AWMF) with participation of 10 medical associations. A literature search was performed until February 1, 2021, to answer 10 key questions. The Oxford Centre for Evidence-Based Medicine (CEBM) System ("The Oxford 2011 Levels of Evidence") was used to classify types of studies in terms of validity. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of evidence and for grading guideline recommendation, and a formal consensus-building process was performed.

RESULTS

The guideline includes 34 evidence-based recommendations about indications, prescription, monitoring and discontinuation of oxygen therapy in acute care. The main indication for O2 therapy is hypoxemia. In acute care both hypoxemia and hyperoxemia should be avoided. Hyperoxemia also seems to be associated with increased mortality, especially in patients with hypercapnia. The guideline provides recommended target oxygen saturation for acute medicine without differentiating between diagnoses. Target ranges for oxygen saturation are based depending on ventilation status risk for hypercapnia. The guideline provides an overview of available oxygen delivery systems and includes recommendations for their selection based on patient safety and comfort.

CONCLUSION

This is the first national guideline on the use of oxygen in acute care. It addresses health care professionals using oxygen in acute out-of-hospital and in-hospital settings.

[Oxygen in the acute care of adults : Short version of the German S3 guideline]

Hintergrund

Sauerstoff (O₂) ist ein Arzneimittel mit spezifischen Eigenschaften, einem definierten Dosis-Wirkungs-Bereich und O₂ hat unerwünschte Wirkungen. Im Jahr 2015 wurden 14 % einer Stichprobe von britischen Krankenhauspatienten mit Sauerstoff behandelt, davon hatten nur 42 % eine Verordnung. Gesundheitspersonal ist häufig unsicher über die Relevanz einer Hypoxämie und es besteht ein eingeschränktes Bewusstsein für die Risiken einer Hyperoxämie. In den letzten Jahren wurden zahlreiche randomisierte, kontrollierte Studien zur Sauerstofftherapie veröffentlicht.

Methoden

Im Rahmen des Leitlinienprogramms der Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e. V. (AWMF) wurde unter Beteiligung von 10 Fachgesellschaften diese S3-Leitlinie auf Basis einer Literaturrecherche bis zum 01.02.2021 entwickelt. Zur Literaturbewertung wurde das System des Oxford Centre for Evidence-Based Medicine (CEBM; „The Oxford 2011 Levels of Evidence“) verwendet. Die Bewertung der Evidenzqualität erfolgte anhand des Grading of Recommendations Assessment, Development and Evaluation (GRADE) und die Leitlinienempfehlungen wurden formal konsentiert.

Ergebnisse

Die Leitlinie enthält 34 evidenzbasierte Empfehlungen zu Indikation, Verordnung, Überwachung und Abbruch der Sauerstofftherapie in der Akutversorgung. Die Indikation für Sauerstoff ist hauptsächlich die Hypoxämie. Hypoxämie und Hyperoxämie sollten aufgrund der Assoziation mit einer erhöhten Sterblichkeit vermieden werden. Die Leitlinie empfiehlt Zielbereiche der Sauerstoffsättigung für die Sauerstoff-Akuttherapie ohne Differenzierung zwischen verschiedenen Diagnosen. Zielbereiche sind abhängig vom Hyperkapnierisiko und Beatmungsstatus. Die Leitlinie bietet einen Überblick über verfügbare Sauerstoffzufuhrsysteme und enthält Empfehlungen für deren Auswahl basierend auf Patientensicherheit und -komfort.

Fazit

Dies ist die erste nationale Leitlinie zum Einsatz von Sauerstoff in der Akutmedizin. Sie richtet sich an medizinisches Fachpersonal, das Sauerstoff außerklinisch und stationär anwendet, und ist bis zum 30.06.2024 gültig.

[German S3 Guideline - Oxygen Therapy in the Acute Care of Adult Patients]

BACKGROUND

 Oxygen (O₂) is a drug with specific biochemical and physiologic properties, a range of effective doses and may have side effects. In 2015, 14 % of over 55 000 hospital patients in the UK were using oxygen. 42 % of patients received this supplemental oxygen without a valid prescription. Healthcare professionals are frequently uncertain about the relevance of hypoxemia and have low awareness about the risks of hyperoxemia. Numerous randomized controlled trials about targets of oxygen therapy have been published in recent years. A national guideline is urgently needed.

METHODS

 A S3-guideline was developed and published within the Program for National Disease Management Guidelines (AWMF) with participation of 10 medical associations. Literature search was performed until Feb 1st 2021 to answer 10 key questions. The Oxford Centre for Evidence-Based Medicine (CEBM) System ("The Oxford 2011 Levels of Evidence") was used to classify types of studies in terms of validity. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used and for assessing the quality of evidence and for grading guideline recommendation and a formal consensus-building process was performed.

RESULTS

 The guideline includes 34 evidence-based recommendations about indications, prescription, monitoring and discontinuation of oxygen therapy in acute care. The main indication for O₂ therapy is hypoxemia. In acute care both hypoxemia and hyperoxemia should be avoided. Hyperoxemia also seems to be associated with increased mortality, especially in patients with hypercapnia. The guideline provides recommended target oxygen saturation for acute medicine without differentiating between diagnoses. Target ranges for oxygen saturation are depending on ventilation status risk for hypercapnia. The guideline provides an overview of available oxygen delivery systems and includes recommendations for their selection based on patient safety and comfort.

CONCLUSION

 This is the first national guideline on the use of oxygen in acute care. It addresses healthcare professionals using oxygen in acute out-of-hospital and in-hospital settings. The guideline will be valid for 3 years until June 30, 2024.

[Oxygen Therapy in Lung Transplantation Candidates - A Single Center Retrospective Analysis of 807 Patients]

BACKGROUND

 Long-term oxygen treatment (LTOT) is frequently used in patients with advanced pulmonary diseases and respiratory failure. Oxygen treatment influences donor lung allocation for patients and is associated with increased mortality. This study investigates oxygen therapy in lung transplantation candidates.

METHODS

 A retrospective study at a large German transplantation centre between 09/2011 and 01/2019 was performed. Data regarding oxygen therapy was analyzed and LTOT-indication verified by titrated blood gas analysis. The study period splits into 2 periods before and after the introduction of oxygen titration (3rd quarter of 2015). Univariate and multivariate analysis for the endpoint "admission to waiting list" was performed.

RESULTS

 807 patients were included in the analysis, 396 in the first and 411 patients in the second period. Of those 293 patients (36.3 %) were transplanted. Six hundred thirty (78 %) patients stated using oxygen for more than 12 hours per day. After implementing oxygen titration in period 2, in 212 (57 %) of 372 patients LTOT indication could be confirmed. Titrated oxygen flow was lower in period 2 (0.5 l/min [IQR 0.0 - 2.0] versus 2 l/min [IQR 0.5 - 3.0]). In multivariate analysis oxygen flow was associated with admission to waiting list as an independent variable.

CONCLUSION

 Patients referred to lung transplantation use oxygen therapy in the vast majority. Indication for LTOT should be carefully reassessed in candidates. Confirmed LTOT-indication seems to be associated with the likelihood for admission to the waiting list for lung transplantation and could therefore be a selection criterium in the future.

End-tidal CO2 and transcutaneous CO2 : Are we ready to replace arterial CO2 in awake children?

INTRODUCTION

Arterial blood gas analysis (ABG) is the gold standard test for carbon dioxide measurement. End-tidal PCO₂ (PetCO₂ ) and transcutaneous PCO₂ (PtcCO₂ ) are noninvasive alternative methods.

OBJECTIVE

To examine the use of PetCO₂ and PtcCO₂ as PaCO₂ surrogates in awake children.

METHODS

A prospective observational study. Consecutive awake children in a stable condition referred to the Sleep Unit of Hospital de Pediatría Dr. J. P. Garrahan with suspected or confirmed sleep-related respiratory disorders requiring ABG were included. PetCO₂ and PtcCO₂ were recorded simultaneously during arterial puncture. PetCO₂ and PtCO₂ values were compared with PaCO₂ . Correlation coefficient and Bland-Altman analysis were applied. The sample size was calculated considering a mean difference ≤3 mmHg as clinically acceptable.

RESULTS

Sixty-eight sample sets were obtained from 67 patients. The median age was 9.11 years (0.23-18.76). During 94.1% of the procedures patients breathed spontaneously, 30% needed multiple punctures and 92% resulted in pain. Median (IQR) PaCO₂ (mmHg) was 36.3 (31.45; 40.90), PetCO₂ 33.0 (29; 39) and PtcCO₂ 38.8 (32.95; 43.32). Correlation and agreement for PaCO₂ /PetCO₂ and PaCO₂ /PtcCO₂ was r = .6 and .9, and media of bias = 2.83 (-9.97; 15.64) and -1.88 (-9.01; 5.24), respectively. Hypercapnia (PaCO₂  > 45.0 mmHg) was present in 8/68 (11.8%) samples. Sensitivity, specificity, positive predictive value and negative predictive value to detect hypercapnia with PetCO₂ was 38%, 98%, 75%, and 92%, respectively, and with PtcCO₂ , 100%, 90%, 57%, and 100%, respectively.

CONCLUSION

PtcCO₂ showed better agreement with PaCO₂ than PetCO₂ but because of the wide dispersion of values, neither method can replace the gold standard. Transcutaneous CO₂ might be a good screening tool to detect hypercapnia in awake children.

Evaluation of Mathematical Arterialization of Venous Blood in Intensive Care and Pulmonary Ward Patients

BACKGROUND

Arterial blood gases are important when assessing acute or critically ill patients. Capillary blood and mathematical arterialization of venous blood have been proposed as alternative methods, eliminating pain and complications of arterial puncture.

OBJECTIVES

This study compares the arterial samples, arterialized venous samples, and capillary samples in ICU and pulmonary ward patients.

METHOD

Ninety-one adult patients with respiratory failure were included in the analysis. Arterial, peripheral venous, and mathematically arterialized venous samples were compared in all patients using Bland-Altman analysis, with capillary samples included in 36 patients.

RESULTS

Overall for pH and PCO2, arterialized venous values, and in the subset of 36 patients, capillary values, compared well to arterial values and were within the pre-defined clinically acceptable differences (pH ± 0.05 and PCO2 ± 0.88 kPa). For PO2, arterialized or capillary values describe arterial with similar precision (PO2 arterialized -0.03, LoA -1.48 to 1.42 kPa and PO2 capillary 0.82, LoA -1.36 to 3 kPa), with capillary values underestimating arterial.

CONCLUSIONS

Mathematical arterialization functions well in a range of patients in an ICU and ward outside the country of development of the method. Furthermore, accuracy and precision are similar to capillary blood samples. When considering a replacement for arterial sampling in ward patients, using capillary sampling or mathematical arterialization should depend on logistic ease of implementation and use rather than improved measurements of using either technique.

Long-Term Mechanical Ventilation: Recommendations of the Swiss Society of Pulmonology

Long-term mechanical ventilation is a well-established treatment for chronic hypercapnic respiratory failure (CHRF). It is aimed at improving CHRF-related symptoms, health-related quality of life, survival, and decreasing hospital admissions. In Switzerland, long-term mechanical ventilation has been increasingly used since the 1980s in hospital and home care settings. Over the years, its application has considerably expanded with accumulating evidence of beneficial effects in a broad range of conditions associated with CHRF. Most frequent indications for long-term mechanical ventilation are chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular and chest wall diseases. In the current consensus document, the Special Interest Group of the Swiss Society of Pulmonology reviews the most recent scientific literature on long-term mechanical ventilation and provides recommendations adapted to the particular setting of the Swiss healthcare system with a focus on the practice of non-invasive and invasive home ventilation in adults.

[Guideline for Long-Term Oxygen Therapy - S2k-Guideline Published by the German Respiratory Society]

Long-term oxygen therapy is of great importance both for reducing mortality and for improving performance in patients with chronic lung diseases. The prerequisites for Long-term oxygen therapy are adequate diagnostics and clearly defined indication. A causal distinction into chronic hypoxaemic and hypercapnic respiratory failure is reasonable, from which the differential indication for non-invasive ventilation results.The revised guideline covers the diagnostics and indication of chronic lung and heart diseases, the role of oxygen in terminal illness and gives a detailed description of available oxygen devices. The guideline is intended to help avoid undersupply, oversupply and false prescriptions. Furthermore, the chapter "Postacute Oxygen Therapy" discusses the procedure, relevant in everyday life, but not yet clearly defined, for prescribing oxygen therapy for the home at the end of an inpatient stay. Another important point, the correct prescription of mobile oxygen systems, is also presented in the guideline. This document is a revised version of the guideline for longterm oxygen therapy and replaces the version of 2008.

A broad diversity in oxygen affinity to haemoglobin

Oxygen affinity to haemoglobin is indicated by the p50 value (pO₂ at 50% O₂Hb) and critically determines cellular oxygen availability. Although high Hb-O₂ affinity can cause tissue hypoxia under conditions of well O₂ saturated blood, individual differences in p50 are commonly not considered in clinical routine. Here, we investigated the diversity in Hb-O₂ affinity in the context of physiological relevance. Oxyhaemoglobin dissociation curves (ODCs) of 60 volunteers (18–40 years, both sexes, either endurance trained or untrained) were measured at rest and after maximum exercise (VO₂max) test. At rest, p50 values of all participants ranged over 7 mmHg. For comparison, right shift of ODC after VO₂max test, representing the maximal physiological range to release oxygen to the tissue, indicated a p50 difference of up to 10 mmHg. P50 at rest differs significantly between women and men, with women showing lower Hb-O₂ affinity that is determined by higher 2,3-BPG and BPGM levels. Regular endurance exercise did not alter baseline Hb-O₂ affinity. Thus, p50 diversity is already high at baseline level and needs to be considered under conditions of impaired tissue oxygenation. For fast prediction of Hb-O₂ affinity by blood gas analysis, only venous but not capillary blood samples can be recommended.

Efficacy and Safety of Using High-Flow Nasal Oxygenation in Patients Undergoing Rapid Sequence Intubation

Objective

To assess the efficacy and safety of high-flow nasal oxygen (HFNO) therapy in patients undergoing rapid sequence intubation (RSI) for emergency abdominal surgery.

Methods

HFNO of 60 L.min^-1 at an inspiratory oxygen fraction of 1 was delivered 4 min before laryngoscopy and maintained until the patient was intubated, and correct intubation was verified by the appearance of the end-tidal CO₂ (EtCO₂) waveform. Transcutaneous oxygenation (SpO₂), heart rate and non-invasive mean arterial pressure were monitored at baseline (T0), after 4 min on HFNO (T1) and at the time of laryngoscopy (T2) and endotracheal intubation (ETI) (T3). An SpO₂ of <3% from baseline was recorded at any sampled time. The value of EtCO₂ at T3 was registered after two mechanical breaths. The apnoea time was defined as the time from the end of propofol injection to ETI. RSI was performed with propofol, fentanyl and rocuronium.

Results

Forty-five patients were enrolled. SpO₂ levels showed a statistically significant increase at T1, T2 and T3 compared with those at T0 (p<0.05); median SpO₂% (interquartile range) was 97% (range, 96%-99%) at T0, 99% (range, 99%-100%) at T1, 99% (range, 99%-100%) at T2 and 99% (range, 99%-100%) at T3. Minimal SpO₂ was 96%; no patient showed an SpO₂ of <3% from baseline; mean EtCO₂ at the time of ETI was 36±4 mmHg. Maximum apnoea time was 12 min.

Conclusion

HFNO is an effective and safe technique for pre-oxygenation in patients undergoing rapid sequence induction of general anaesthesia for emergency surgery.

Capillary PO2 does not adequately reflect arterial PO2 in hypoxemic COPD patients

Purpose

To compare arterial (P_aO₂) with capillary (P_cO₂) partial pressure of oxygen in hypoxemic COPD patients because capillary blood gas analysis (CBG) is increasingly being used as an alternative to arterial blood gas analysis (ABG) in a non-intensive care unit setting, although the agreement between P_cO₂ and P_aO₂ has not been evaluated in hypoxemic COPD patients.

Patients and methods

Bland–Altman comparison of P_aO₂ and P_cO₂ served as the primary outcome parameter if P_cO₂ values were ≤60 mmHg and the secondary outcome parameter if P_cO₂ values were ≤55 mmHg. Pain associated with the measurements was assessed using a 100-mm visual analog scale.

Results

One hundred and two P_aO₂/P_cO₂ measurement pairs were obtained. For P_cO₂ values ≤60 mmHg, the mean difference between P_aO₂ and P_cO₂ was 5.99±6.05 mmHg (limits of agreement: −5.88 to 17.85 mmHg). For P_cO₂ values ≤55 mmHg (n=73), the mean difference was 5.33±5.52 mmHg (limits of agreement: −5.48 to 16.15 mmHg). If P_aO₂ ≤55 (≤60) mmHg was set as the cut-off value, in 20.6% (30.4%) of all patients, long-term oxygen therapy have been unnecessarily prescribed if only P_cO₂ would have been assessed. ABG was rated as more painful compared with CBG.

Conclusions

P_cO₂ does not adequately reflect P_aO₂ in hypoxemic COPD patients, which can lead to a relevant number of unnecessary long-term oxygen therapy prescriptions.

Home oxygen therapy: evidence versus reality

INTRODUCTION

LTOT is a well-established treatment option for hypoxemic patients. Scientific evidence for its benefits of LTOT dates back to the 1980s, when two randomized controlled trials showed prolonged survival in COPD-patients undergoing LTOT for at least 15 hours/day. In contrast, the potential benefits of LTOT in non-COPD-patients has not been well researched and the recommendations for its application are primarily extrapolated from trials on COPD-patients. Recently, a large trial confirmed that COPD-patients who don't meet classic indication criteria, and have moderate desaturation at rest or during exercise, do not benefit from oxygen therapy. Also the significant technical evolution of LTOT devices has improved its application. Areas covered: A literature research was performed in pubmed regarding home oxygen therapy (terms: LTOT, ambulatory oxygen therapy, short burst oxygen therapy, nocturnal oxygen therapy). Expert commentary: LTOT proved a survival benefit for COPD patients about 30 years ago. Whether the results of these trials are still valid for patients under modern treatment guidelines remains unknown. Nevertheless, the classic indication criteria for LTOT still persist in guidelines, since there is a lack of updated evidence for the effects of LTOT in more severe hypoxemic patients.

Assessment of Sleep in Patients Receiving Invasive Mechanical Ventilation in a Specialized Weaning Unit

INTRODUCTION

A restful sleep is essential for regenerative processes and remains crucial for patients recovering from stressful periods in the intensive care unit. The current study aimed to assess sleep quality in critically ill patients receiving invasive mechanical ventilation within a specialized weaning unit in hospital.

METHODS

Tracheotomized subjects undergoing prolonged weaning from mechanical ventilation were included in the study. Polysomnography and gas exchange monitoring was performed during nocturnal ventilation. Subjective evaluation of sleep quality and health-related quality of life were also assessed.

RESULTS

Nineteen subjects completed the study protocol. Sleep architecture was highly heterogeneous across individual subjects. Mean total sleep time (TST) was 273 ± 114 min, sleep efficacy 70 ± 23%, slow-wave sleep 25.7 ± 18.4%/TST, rapid eye movement sleep 9.6 ± 7.5%/TST, and arousal index 18.7 ± 12.4/h. No significant difference in sleep quality was found between subjects with successful (N = 7) or unsuccessful (N = 12) weaning. Bicarbonate levels were negatively correlated both with sleep efficacy and sleep quality, that latter of which was subjectively assessed by the subjects using a visual analogue scale.

CONCLUSION

Subjects who were undergoing prolonged weaning from mechanical ventilation and admitted to a specialized weaning unit, showed reduced sleep quality with preservation of high amounts of slow-wave sleep.

[Monitoring of pCO2 during ventilation]

Respiratory insufficiency type 2 (ventilatory failure) is characterized by hypercapnia due to alveolar hypoventilation. Therefore, the monitoring of pCO2 is essential for diagnostic and surveillance purposes. Various techniques which differ in the way of measurement (e.g., invasive/noninvasive, continuous/noncontinuous) and their indication are available. Arterial blood gas analysis (ABG) as an invasive procedure is the gold standard procedure and is mostly used in emergency medicine or intensive care units (ICUs). Another method to evaluate pCO2 is capillary blood gas analysis (CBG). Furthermore, endtidal pCO2-(PetCO2) and transcutaneous CO2-measurement (PtcCO2) are able to continuously and noninvasively monitor pCO2. PetCO2 is mostly used in the field of anesthesiology during general anesthesia and is integrated in many ventilators, also in ICUs. However, PetCO2 is limited in monitoring pCO2 in patients with lung disease and it is only reasonably usable in invasively ventilated patients. Transcutaneous pCO2 (PtcCO2) is available as an alternative, especially in chronic respiratory failure and to diagnose hypoventilation in sleep-related breathing disorders, and it has substantial advantages in these indications compared to discontinuous measurements, e.g., blood gas analysis. The various methods to monitor pCO2 are generally used synergistically in clinical practice.