Respiratory Acidosis Research Articles

The effects of targeting mild hypercapnia on right ventricular function after out-of-hospital cardiac arrest. A sub-study of the TAME trial.

Abstract Background The Targeted Therapeutic Mild Hypercapnia After Resuscitated Cardiac Arrest (TAME) trial found similar neurological outcomes between mild hypercapnia and normocapnia in resuscitated out-of- hospital cardiac arrest (OHCA) patients. Hypercapnic acidosis can cause pulmonary vasoconstriction and aggravate right ventricular dysfunction, which is common and associated with worsened outcomes after OHCA. Purpose We investigated the effects of targeting mild hypercapnia on right ventricular function. Methods Single-centre, pre-planned and prospective sub-study. Comatose OHCA patients were randomised to targeted mild hypercapnia (PaCO2 =6.7–7.3 kPa) or targeted normocapnia (PaCO 2 =4.7- 6.0 kPa) for 24 hours. Transthoracic echocardiography was performed at baseline, during intervention and 48 hours after randomisation. Serial right heart catherisation (RHC) was performed if available. Results A total of 137 patients were randomised, 111 were evaluated with echocardiography and 52 and 59 randomised to mild hypercapnia and normocapnia, respectively. 84 patients received RHC; 41 and 43 in the hypercapnia and normocapnia-group, respectively. Overall, the median age was 64 years, 80 % were male and median time to ROSC was 22 minutes. Baseline characteristics did not differ significantly between treatments groups (p >0.05). Targeting mild hypercapnia was associated with lower tidal volumes, respiratory frequencies and respiratory acidosis (P-group < 0.05). Positive end-expiratory pressure, right atrial pressure, pulmonary vascular resistance index and pulmonary capillary wedge pressure were similar between groups (P-group > 0.05). Median time to echocardiography after randomisation was 21 (IQR 14-23) and 17 (IQR 9-22) hours in the hypercapnia and normocapnia-group, respectively. Tricuspid annular plane systolic excursion (TAPSE) was similar between treatment-groups at baseline and higher in the hypercapnia-group during the intervention with a median of 21 mm (IQR 18-23) versus 16 mm (IQR 13-21), p = 0.002. S', fractional area change (FAC) and the ratio of TAPSE to the pulmonary artery systolic pressure (PASP) were all higher in the hypercapnia-group during the intervention. Overall, median left ventricular ejection fraction was 45 % (IQR 38-55) without treatment group differences (p=0.2). Both invasive and echocardiographic assessment found increased cardiac index and stroke volumes in the hypercapnia-group (p <0.05). Right ventricular stroke work index (RVSWI) was consistently higher in the hypercapnia-group throughout the intervention (P-group < 0.001), while the pulmonary artery pulsatility index did not differ (P-group >0.05). Conclusions In patients resuscitated from OHCA, targeting mild hypercapnia compared to normocapnia was associated with increased TAPSE, S', FAC, TAPSE:PASP, RVSWI and cardiac index. Contrary to our prior concern these results indicate improved right ventricular function while targeting mild hypercapnia.

Pattern and associated factors of COVID-19 knowledge, attitude and practice (KAP) among COVID-19-comorbid patients: a systematic review and meta-analysis

BackgroundThe COVID-19 comorbid population is at higher risk of developing severe health issues like acute respiratory distress syndrome, coagulation syndrome, metabolic acidosis, and septic shock, potentially leading to patient death. Patients’ knowledge, attitudes, and practices (KAP) significantly influence their response to the pandemic and aid in enhancing health policy implementation.ObjectiveTo identify and evaluate the pattern and associated factors to COVID-19 knowledge, attitude, and practice among individuals with comorbidities.MethodologyThe systematic review followed the PRISMA guidelines. Relevant studies assessing the KAP of comorbid patients were retrieved by carefully searching the PubMed and Google Scholar databases. The appraisal tool for cross-sectional studies was used to determine the quality of the included studies and the risk of biases.ResultsEighteen studies met the inclusion criteria and were included in the review. The pooled sample size of the included studies was 9,104. Different comorbidities reported in the studies include hypertension, diabetes, psychological disorders, and cancer. Pooled analysis showed that 65% of patients showed good knowledge, 57% of patients showed a positive attitude and 51% of patients followed good practices to manage the COVID-19 in presence of their comorbid condition. Significant factors impacting knowledge, attitude and practice in COVID-19 comorbid patients were ethnicity OR 1.78 [95% CI 1.35–2.32]; educational status 3.2 [2.79–3.58]; urban residence 2.43 [1.65–3.02]; employment Status 1.67[1.34–2.12]; financial Status 4.02[3.66–4.38]; occupation 3.65[3.31–4.25]; information Source 2.64[2.19–3.26]; comorbidity 3.28[2.78–3.61]; and duration of chronic illness 1.59[1.31–2.04].ConclusionComorbid COVID-19 patients showed good knowledge, positive attitude and good practice towards the management of the disease.

A systematic review on the use of sevoflurane in the management of status asthmaticus in adults

BackgroundTo conduct a systematic review looking into the use of sevoflurane in the management of status asthmaticus (SA) in adults.MethodsWe performed a systematic search on PubMed, EMBASE, and The Cochrane Library – CENTRAL through 23rd August 2023, restricting to studies reported in English. We included studies reporting use of sevoflurane in asthmatics beyond its use as an anaesthetic agent in surgeries i.e. in the emergency department (ED) and critical care setting, and focused on patient’s clinical parameters, ventilation pressures and weaning of invasive ventilation.ResultsA total of 13 publications fulfilled the inclusion criteria, comprising of 18 cases. All publications were of case reports/ series and conference abstracts, and no randomised trials were available. Most patients required intubation despite best medical management before sevoflurane administration, and high airway pressures and respiratory acidosis were apparent. There was significant heterogeneity regarding severity of asthma, treatment instituted, and the delivery, duration and concentration of sevoflurane administered. Many of the studies also did not quantify the changes in parameters pre- and post-sevoflurane. Sixteen patients experienced improvements in clinical status with sevoflurane administration—one required escalation to extracorporeal membrane oxygenation (ECMO), and another did not survive.ConclusionThe systematic review suggests sevoflurane can be a valuable treatment option in SA. As these cases are rare and heterogenous, further prospective case series are needed to support this.

7378 Glargine Induced Neuroglycopenia in Patients with End-Stage Renal Disease: Importance of Insulin Regimen Optimization in Haemodialysis Patients

Abstract Disclosure: M. Shrivastava: None. L. Kaur: None. B. Armendariz: None. R. Kaur: None. A. Shetty: None. In patients with end stage renal disease (ESRD), hypoglycemia accounts for up to 3.6% of all the admissions with mortality rates of up to 30%. A combination of impaired insulin clearance, changes in glucose metabolism and dialysis process makes the patients with end stage renal disease vulnerable to neuroglycopenia.Case description:53 year old female with past medical history of insulin dependent type 2 diabetes mellitus, ESRD secondary to diabetes, on hemodialysis(HD) thrice weekly since two years, presented to the emergency with altered mental status, respiratory distress, tachycardia. Lab work revealed blood glucose(BG) of 23 mg/dl, HbA1c of 8.4%, eGFR of 6, and arterial blood gas showed hypercapnic respiratory acidosis. Patient received dextrose, with no improvement of symptoms. Eventually she developed acute hypercapnic respiratory failure requiring endotracheal intubation with mechanical ventilation, and was transferred to the ICU. As per family, a night prior to presentation, last recorded BG after dinner was 253 mg/dl, she took her night time glargine, which was recently increased by her primary care for poorly controlled HbA1c levels. Brain MRI and long term EEG monitoring findings were consistent with underlying extensive brain injury secondary to prolonged hypoglycemia. Unfortunately, the patient's condition did not improve despite HD and BG correction, eventually she underwent compassionate extubation. Case Discussion:The insulin requirements in ESRD patients are reduced by approximately 50%, regardless of residual insulin secretion. Malnutrition and acidosis reduce hepatic glycogen stores and availability of gluconeogenic precursor, expected compensatory renal gluconeogenesis is compromised by decreased renal function causing hypoglycemia, which is further worsened by inappropriately high plasma insulin levels caused by reduced renal insulin breakdown. Diabetes mellitus patients with ESRD are frequently managed with basal-bolus insulin regimen, and HD up to thrice weekly, leaving them without HD for up to 3 days especially over the weekend. This can result in accumulation of insulin metabolites causing delayed insulin clearance as seen in our patient. In such cases even long acting insulin, such as glargine, can have compounding effects, which could possibly cause fatal complications such as neuroglycopenia. In such patients continuous glucose monitor use with tapering dose glargine regimen may help eliminate this compounding effect. Conclusion: Neuroglycopenia is a rare manifestation of diabetes mellitus with ESRD. Compromised renal gluconeogenesis and impaired insulin clearance can cause inappropriately high plasma levels of insulin. In such patients continuous glucose monitoring along with tapering dose of long acting insulin should be utilized for proper glycemic control to limit compounded effect of insulin metabolite accumulation. Presentation: 6/3/2024

Effect of Chlordiazepoxide or Haloperidol Oral Premedication during Midazolam-Ketamine Anaesthesia on Physiological and Blood Gas Parameters in Adult Male Bonnet Macaques (Macaca radiata)

Capturing wild animals with minimal stress is crucial to reduce morbidity and mortality. Oral premedicants can ease handling and subsequent anaesthetic administration. This study evaluated anaesthetic protocols and physiological changes during vasectomy in 12 adult male Bonnet Macaques. Group I received 10 mg/kg chlordiazepoxide, and Group II received 1 mg/kg haloperidol orally four hours before midazolam-ketamine anaesthesia. Sedation quality, induction, maintenance, and recovery were assessed. Physiological and blood gas changes were monitored at 0, 5, 10, 15, and 20 minutes. Both groups exhibited sedation post-premedication. Induction, maintenance, and anaesthesia depth were similar. Group I had better analgesia, while Group II had superior muscle relaxation. Blood gas analysis indicated mild stress and respiratory acidosis in both groups, with Group II showing more significant hypoxemia and respiratory acidosis. Haloperidol-premedicated animals were easier to handle but exhibited increased stress parameters compared to chlordiazepoxide-premedicated animals. Recovery was better in Group I. Both protocols effectively induced sedation and anaesthesia in Bonnet Macaques.

Respiratory Acidosis in Salicylate Toxicity: An Unusual Initial Presentation

Respiratory Acidosis in Salicylate Toxicity: An Unusual Initial Presentation

Soluble adenylyl cyclase is an acid-base sensor in rainbow trout red blood cells that regulates intracellular pH and haemoglobin-oxygen binding.

To identify the physiological role of the acid-base sensing enzyme, soluble adenylyl cyclase (sAC), in red blood cells (RBC) of the model teleost fish, rainbow trout. We used: (i) super-resolution microscopy to determine the subcellular location of sAC protein; (ii) live-cell imaging of RBC intracellular pH (pHi) with specific sAC inhibition (KH7 or LRE1) to determine its role in cellular acid-base regulation; (iii) spectrophotometric measurements of haemoglobin-oxygen (Hb-O2) binding in steady-state conditions; and (iv) during simulated arterial-venous transit, to determine the role of sAC in systemic O2 transport. Distinct pools of sAC protein were detected in the RBC cytoplasm, at the plasma membrane and within the nucleus. Inhibition of sAC decreased the setpoint for RBC pHi regulation by ~0.25 pH units compared to controls, and slowed the rates of RBC pHi recovery after an acid-base disturbance. RBC pHi recovery was entirely through the anion exchanger (AE) that was in part regulated by HCO3 --dependent sAC signaling. Inhibition of sAC decreased Hb-O2 affinity during a respiratory acidosis compared to controls and reduced the cooperativity of O2 binding. During invitro simulations of arterial-venous transit, sAC inhibition decreased the amount of O2 that is unloaded by ~11%. sAC represents a novel acid-base sensor in the RBCs of rainbow trout, where it participates in the modulation of RBC pHi and blood O2 transport though the regulation of AE activity. If substantiated in other species, these findings may have broad implications for our understanding of cardiovascular physiology in vertebrates.

Acute Hypophosphatemia Due to Rapid Correction of Respiratory Acidosis

Acute Hypophosphatemia Due to Rapid Correction of Respiratory Acidosis

Control of hyperpnoea and pulmonary gas exchange during prolonged exercise: The role of group III/IV muscle afferent feedback.

It remains unclear whether feedback from group III/IV muscle afferents is of continuous significance for regulating the pulmonary response during prolonged (>5min), steady-state exercise. To elucidate the influence of these sensory neurons on hyperpnoea, gas exchange efficiency, arterial oxygenation and acid-base balance during prolonged locomotor exercise, 13healthy participants (4 females; 21 (3) years, : 46 (8) ml/kg/min) performed consecutive constant-load cycling bouts at ∼50% (20min), ∼75% (20min) and ∼100% (5min) of with intact (CTRL) and pharmacologically attenuated (lumbar intrathecal fentanyl; FENT) group III/IV muscle afferent feedback from the legs. Pulmonary responses were continuously recorded and arterial blood (radial catheter) periodically collected throughout the exercise. Pulmonary gas exchange efficiency was evaluated using the alveolar-arterial difference ( ). There were no differences in any of the variables of interest between conditions before the start of the exercise. Pulmonary ventilation was up to 20% lower across all intensities during FENT compared to CTRL exercise (P<0.001) and this hypoventilation was accompanied by an up to 10% lower arterial and a 2-4mmHg higher (both P<0.001). The exercise-induced widening of was up to 25% larger during FENT compared to CTRL (P<0.001). Importantly, the differences developed within the first minute of each stage and persisted, or further increased, throughout the remainder of each bout. These findings reflect a critical and time-independent significance of feedback from group III/IV leg muscle afferents for continuously regulating the ventilatory response, gas exchange efficiency, arterial oxygenation and acid-base balance during human locomotion. KEY POINTS: Feedback from group III/IV leg muscle afferents reflexly contributes to hyperpnoea during short duration (i.e. <5min) locomotor exercise. Whether continuous feedback from these sensory neurons is obligatory to ensure adequate pulmonary responses during steady-state exercise of longer duration remains unknown. Lumbar intrathecal fentanyl was used to attenuate the central projection of group III/IV leg muscle afferents during prolonged locomotor exercise (i.e. 45min) at intensities ranging from 50% to 100% of . Without affecting the metabolic rate, afferent blockade compromised pulmonary ventilation and gas exchange efficiency, consistently impairing arterial oxygenation and facilitating respiratory acidosis throughout exercise. These findings reflect the time-independent significance of feedback from group III/IV muscle afferents for regulating exercise hyperpnoea and gas exchange efficiency, and thus for optimizing arterial oxygenation and acid-base balance, during prolonged human locomotion.

CLINICAL SPECTRUM OF DISEASE IN NEONATES BORN TO MOTHERS WITH COVID-19 IN A TERTIARY CARE HOSPITAL

COVID-19 infection during pregnancy presents potential risks to neonates, yet the full clinical spectrum in newborns born to COVID-19-positive mothers remains under investigation. Understanding the clinical outcomes in these neonates is essential for guiding management and care. Objective: To study the spectrum of clinical presentations in neonates born to mothers who tested positive for COVID-19. Methods: This prospective cross-sectional study was conducted at the Department of Pediatrics, Shifa International Hospital, from April 1, 2020, to April 30, 2021. All neonates born to COVID-19-positive mothers were included in the study and followed daily during their hospital stay. After obtaining parental consent, nasopharyngeal swabs were taken from the neonates for SARS-CoV-2 PCR testing at 24-48 hours of age. After discharge, follow-up calls were made between days 7-14. Data were entered into a predesigned proforma and analyzed using SPSS version 23. Results: A total of 82 neonates were enrolled. Approximately half were born at term, with a mean weight of &gt;2500 grams. Forty-five neonates (53%) underwent SARS-CoV-2 PCR testing within 48 hours of age; all were negative. Sixty-one neonates (74%) were shifted to the mother’s care, while 25% required admission to the neonatal intensive care unit (NICU). The most common reasons for NICU admission included respiratory distress (15%), prematurity (6%), and lethargy (5%). Radiological findings included ground-glass appearance in five neonates (6%) and lung consolidation or infiltrates in two (3%). Hematological and biochemical abnormalities included leukocytosis (7%), leucopenia (3.6%), anemia (1.2%), metabolic acidosis (6%), and respiratory acidosis (3.6%). Most neonates (78.6%) received routine care and were fed breast milk. Fourteen neonates (16.7%) required respiratory support, with 13% needing mechanical ventilation. Complications included pneumonia (7%) and respiratory failure (9%). NICU stay varied, with 11 neonates (13%) staying less than 48 hours and 10 (12%) requiring a more extended stay. Four neonates (5%) died due to multiorgan complications. Conclusion: The majority of neonates born to COVID-19-positive mothers remained asymptomatic. However, symptomatic neonates were at risk of serious complications, requiring close monitoring and management, particularly in those with additional risk factors.

Hypercapnia during transcatheter aortic valve replacement under monitored anaesthesia care: a retrospective cohort study

BackgroundAcute intraoperative hypercapnia and respiratory acidosis, which can occur during monitored anaesthesia care (MAC), pose significant cardiopulmonary risks for patients with aortic stenosis undergoing transcatheter aortic valve replacement (TAVR). The...

Regulation of host metabolism and defense strategies to survive neonatal infection

Two distinct defense strategies, disease resistance (DR) and disease tolerance (DT), enable a host to survive infectious diseases. Newborns, constrained by limited energy reserves, predominantly rely on DT to cope with infection. However, this approach may fail when pathogen levels surpass a critical threshold, prompting a shift to DR that can lead to dysregulated immune responses and sepsis. The mechanisms governing the interplay between DR and DT in newborns remain poorly understood. Here, we compare metabolic traits and defense strategies between survivors and non-survivors in Staphylococcus epidermidis (S. epidermidis)-infected preterm piglets, mimicking infection in preterm infants. Compared to non-survivors, survivors displayed elevated DR during the initial phase of infection, followed by stronger DT in later stages. In contrast, non-survivors showed clear signs of respiratory and metabolic acidosis and hyperglycemia, together with exaggerated inflammation and organ dysfunctions. Hepatic transcriptomics revealed a strong association between the DT phenotype and heightened oxidative phosphorylation in survivors, coupled with suppressed glycolysis and immune signaling. Plasma metabolomics confirmed the findings of metabolic regulations associated with DT phenotype in survivors. Our study suggests a significant association between the initial DR and subsequent DT, which collectively contributes to improved infection survival. The regulation of metabolic processes that optimize the timing and balance between DR and DT holds significant potential for developing novel therapeutic strategies for neonatal infection.

Expert perspectives on ECCO2R for acute hypoxemic respiratory failure: consensus of a 2022 European roundtable meeting

BackgroundBy controlling hypercapnia, respiratory acidosis, and associated consequences, extracorporeal CO2 removal (ECCO2R) has the potential to facilitate ultra-protective lung ventilation (UPLV) strategies and to decrease injury from mechanical ventilation. We convened a meeting of European intensivists and nephrologists and used a modified Delphi process to provide updated insights into the role of ECCO2R in acute respiratory distress syndrome (ARDS) and to identify recommendations for a future randomized controlled trial.ResultsThe group agreed that lung protective ventilation and UPLV should have distinct definitions, with UPLV primarily defined by a tidal volume (VT) of 4–6 mL/kg predicted body weight with a driving pressure (ΔP) ≤ 14–15 cmH2O. Fourteen (93%) participants agreed that ECCO2R would be needed in the majority of patients to implement UPLV. Furthermore, 10 participants (majority, 63%) would select patients with PaO2:FiO2 > 100 mmHg (> 13.3 kPa) and 14 (consensus, 88%) would select patients with a ventilatory ratio of > 2.5–3. A minimum CO2 removal rate of 80 mL/min delivered by continuous renal support machines was suggested (11/14 participants, 79%) for this objective, using a short, double-lumen catheter inserted into the right internal jugular vein as the preferred vascular access. Of the participants, 14/15 (93%, consensus) stated that a new randomized trial of ECCO2R is needed in patients with ARDS. A ΔP of ≥ 14–15 cmH2O was suggested by 12/14 participants (86%) as the primary inclusion criterion.ConclusionsECCO2R may facilitate UPLV with lower volume and pressures provided by the ventilator, while controlling respiratory acidosis. Since recent European Society of Intensive Care Medicine guidelines on ARDS recommended against the use of ECCO2R for the treatment of ARDS outside of randomized controlled trials, new trials of ECCO2R are urgently needed, with a ΔP of ≥ 14–15 cmH2O suggested as the primary inclusion criterion.

Arterial Blood Gas Parameters to Evaluate Oxygenation and Acid-Base Disorders in Corticosteroid-Receiving Severe and Critical COVID-19 Patients

Highlights: Hypoxemia was prevalent in both severe and critical COVID-19 patients. Severe and critical COVID-19 patients might have tendencies towards respiratory alkalosis/metabolic acidosis and respiratory acidosis, respectively. Abstract Introduction: Increased inflammation and immune dysregulation in severe and critical COVID-19 trigger oxygen and acid-base disorders, possibly mitigated by corticosteroids. Variations in arterial blood gas (ABG) parameters and the influence of corticosteroid administration have become a concern for clinicians. This study aimed to uncover significant differences in temporal ABG parameters between severe and critical COVID-19 cases undergoing corticosteroid treatment. Methods: This case-control study, which adhered to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines, analyzed severe (n = 27) and critical (n = 41) COVID-19 patients treated in the high care unit (HCU) and the intensive care unit (ICU) of Universitas Airlangga Hospital, Surabaya, from May to July 2021. ABG results were categorized into three evaluations (E1-E3) based on collection days. The International Business Machines Corporation (IBM) Statistical Package for the Social Sciences (SPSS) for Macintosh version 27.0 was used for statistical analysis. Results: Hypoxemia through PaO2 and P/F ratios was prominent in both groups throughout E1-E3, with differences only in E1 P/F ratios (p = 0.003). While SaO2 stayed normal in severe cases, critical cases were low, with differences in E1 (p = 0.012) and E3 (p = 0.004). Severe cases maintained normal pH, while critical cases tended towards acidemia, notably differing in E1-E3. Both groups had low HCO3 levels, differing only in E2 (p &lt; 0.001). Severe and critical groups exhibited low and high PaCO2 trends, respectively, with distinctions in E2 (p &lt; 0.001) and E3 (p = 0.003). Conclusion: Hypoxemia was prevalent in both groups. Compensated respiratory alkalosis or metabolic acidosis was common in the severe group, while the critical presented with respiratory acidosis.

Lung ultrasound to predict the duration of respiratory support in newborn infants with respiratory distress.

Lung ultrasound (LU) and clinical parameters evaluated during the first postnatal hour potentially predict the length of CPAP therapy in newborns with respiratory distress. In a single-centre, prospective observational pilot study, 130 newborns ≥36 weeks gestational age were assessed using standardised LU at 30 and 60 min postnatally. Various clinical parameters were evaluated influencing CPAP duration (<1 vs. ≥1 h) using univariate and multivariate analyses. Lung ultrasound score >5, FiO2 > 0.21 and respiratory acidosis 30 min postnatally were associated with CPAP ≥1 h. Our model showed good diagnostic quality (ROC AUC = 0.87) and was confirmed by classification and regression tree (CART) analysis. Additional LU findings like double lung point and pleural line abnormalities were frequently observed, with good interrater reliability for LU interpretation (ICC = 0.76-0.77). Newborns with postnatal respiratory distress at risk for prolonged CPAP therapy can be identified based on specific LU and clinical parameters assessed 30 min postnatally. Despite the need for validation in an independent sample, these findings may lay the groundwork for a prediction tool. LU proved feasible and reliable for assessing respiratory status in this population, highlighting potential utility in clinical practice.

Effect of the Heaviness of Smoking Index (HSI) and Duration of Smoking on Central Neural Processing Using Brainstem Auditory Evoked Responses (BAERs).

Purpose of study The goal of this research was to find the correlation of nicotine dependence and duration of smoking with the status of central neuronal processing in chronic smokers. Our primary objective was to record brainstem auditory evoked responses (BAERs) in chronic smokers and further find their correlation to the Heaviness of Smoking Index (HSI) scores and years of non-abstained smoking of the subjects. We postulated that smoking leads to myelination abnormalities which in turn causes decreased impulse conduction velocity. Methods After obtaining informed consent, we conducted BAER on 60 male smokers who were further classified into groups based on their HSI scores (low, moderate, and high nicotine dependency) and 20 age-matched, non-smoking males. The obtained data was examined using the two-way ANOVA test and the Kruskal-Wallis test. Pearson's coefficient of correlationand the median (as a measure of central tendency) were calculated. Results We observed a non-significant negative correlation between wave I BAER latency and the degree of nicotine dependence. Wave II showed minimal correlation, whereas a positive correlation was seen in waves III, IV, and V. Interpeak latencies (IPL) I-III and III-V showed a non-significant positive correlation with the HSI score, whereas IPL I-V showed a significant positive correlation with the same. When correlated with the duration of smoking (years), the latencies (msec) of BAER waves I-V showed a pattern of progressively decreasing negative correlation, out of which waves I, II, and III were significantly affected. The IPL (msec) of waves I-III was non-significantly, yet positively, correlated, while the IPL of waves I-V and III-V showed a significant positive correlation to the duration of smoking. Conclusions The degree of nicotine dependence and duration of tobacco smoking progressively affected the latencies of BAER waves at the pontomedullary level of the brainstem. This indicates slower central neuronal processing at this level and an increased central transmission time, the extent of which is directly dependent on the extent of tobacco smoking. This is attributed to the myelination defects caused by direct and indirect effects of the toxic metabolites of tobacco smoke, chronic hypoxia, hypercapnia, and respiratory acidosis.

Metabolic alkalosis: a new red flag in status epilepticus

BackgroundStatus epilepticus (SE) is a heterogeneous neurological emergency with significant variability in prognosis, influenced by underlying disease and pathophysiological context. Acid–base disturbances are common in critically ill patients, yet their distribution and impact in SE patients remain poorly understood.MethodsThis was an observational cohort study including non-hypoxic SE patients with available blood gas analysis within the first 24 h of SE, treated at the University Hospital of Geneva, Switzerland between 2015 and 2023. Acid–base disturbances were classified using the Henderson–Hasselbalch equation, with prevalent metabolic alkalosis confirmed through the Stewart approach. Primary outcomes were in-hospital mortality, Glasgow Outcome Scale (GOS) at discharge, and return to premorbid neurologic function.FindingsAmong 540 SE patients, 365 were included. Half of patients exhibited acid–base disturbances within the initial 24 h of SE, with metabolic and respiratory acidosis being the most prevalent, though not prognostically significant. After correction for possible confounders, metabolic alkalosis (6%) was associated with increased in-hospital mortality (P = 0.011; OR = 4.87, 95% CI = 1.29–7.84), worse GOS (P = 0.012; OR = 3.18, 95% CI = 1.29–7.84), and reduced likelihood of returning to premorbid function (P = 0.017; OR = 3.30, CI95% = 1.24–8.80). Following the Stewart approach, 9% of patients had predominant metabolic alkalosis, associated with worse GOS (P = 0.005; OR:3.37, 95%CI = 1.45–7.82), and reduced chance of returning to baseline (P = 0.012; OR = 3.29, CI95% = 1.30–8.32). Metabolic alkalosis was related to hypoalbuminemia and lower serum potassium.ConclusionMetabolic alkalosis strongly predicts mortality and adverse functional outcome in SE patients. Prospective studies should assess whether early detection and correction of metabolic alkalosis and related electrolyte imbalances can improve SE prognosis.

A Novel Imaging Device for Percutaneous Dilatational Tracheostomy.

Objective: The purpose of this article is to introduce a novel imaging device and technique for percutaneous dilatational tracheostomy (PDT) and evaluate its clinical application. Methods: We have modified the bronchoscope to generate a novel imaging device. The handle of the bronchoscope was removed and replaced with added fixation pieces to secure the new device to the endotracheal tube. Nine mechanically ventilated patients admitted to the intensive care department of Shandong Public Health Clinical Center who underwent PDT between July 2023 and January 2024 have been treated with this novel imaging device. The number of medical staff members needed for the operation, number of needle interventions, operation time, arterial blood gas analysis, and intraoperative complications were observed. Results: Three medical staff were involved in the procedure: an operator, an assistant, and a nurse. The first attempted needle intervention was successful in all patients, and no serious complications such as major bleeding, pneumothorax, mediastinal emphysema, accidental extubation, desaturation, hypercarbia, respiratory acidosis, hemodynamic abnormality, or posterior tracheal puncture occurred. The average time was 11.63 ± 1.56 minutes from skin incision to the needle insertion and 4.43 ± 1.99 minutes from needle insertion to tracheal placement. Conclusions: PDT guided by the novel device is safe, preserves human resources, saves operating space, keeps the view stable, and makes the procedure easy. It is worthy of further research and application.

Severe respiratory acidosis contributing to refractory hyperkalemia: a case series of COVID-19 patients with renal failure

Introduction: Respiratory acidosis (RA) is not known to cause severe hyperkalemia. However, an exception to this general rule was observed in three patients with severe COVID-19 complicated with renal failure in our center. Objectives: The current study investigated the explanation for hyperkalemia refractory to renal replacement therapy in patients with severe COVID-19 with hypercarbia and renal failure in a tertiary care center. Patients and Methods: In this study, we present a case series of three patients with severe COVID-19 with hypercarbia and dialysis-requiring renal failure who developed persistent hyperkalemia refractory to renal replacement therapy. We studied various causes of persistent hyperkalemia, such as acid‒base disorder, a high turnover state, exogenous administration, rhabdomyolysis, and hypoaldosteronism. Results: All three patients initially presented with episodes of severe hyperkalemia, which were ameliorated after RA was corrected. All of these patients had worsening pulmonary function, after which the hyperkalemia could not be corrected, corresponding to persistent RA. The evidence that there was a contribution of RA to hyperkalemia was further strengthened by the observations of patient 1, in whom the hyperkalemia was only corrected after changing ventilator settings and who was unresponsive to dialysis. We studied the dialysate effluent in patient 3, and the results showed satisfactory removal of potassium with no improvement in the high serum potassium levels. Another interesting finding was that although the dialysate sodium concentration was greater than the serum sodium concentration, there was a decrease in the serum sodium concentration, indicating a reduced movement of sodium into the extracellular space. Conclusion: In our study, metabolic acidosis alone could not explain the high serum potassium levels. Moreover, hyperkalemia was corrected after RA was corrected, indicating that the latter might have been the predominant cause of hyperkalemia in these scenarios. The presence of renal failure and low serum bicarbonate levels might have been the factors contributing to decreased Na+-K+-ATPase activity in the setting of RA, which contributed to severe hyperkalemia in all three patients.

The Non-Invasive Ventilation Outcomes (NIVO) score in patients requiring NIV for COPD exacerbation without prior evidence of airflow obstruction

Exacerbation of Chronic Obstructive Pulmonary disease (COPD) complicated by respiratory acidaemia is the commonest indication for non-invasive ventilation (NIV). The NIV Outcomes (NIVO) score offers the best estimate of survival for those ventilated. Unfortunately 2/3 cases of COPD are unrecognised, and patients may present without COPD having been confirmed by spirometry. In the 10-centre NIVO validation study there was no pre-admission spirometry in 111 of 844 consecutive patients (termed “clinical diagnosis” patients). We compared the performance of the NIVO, DECAF and CURB-65 scores for in-hospital mortality in the clinical diagnosis cohort. Usual clinical practice was not influenced, but confirmation of COPD in the year following discharge was captured. In the clinical diagnosis cohort, in-hospital mortality was 19.8%, and rose incrementally across the NIVO risk categories, consistent with the NIVO validation cohort. NIVO showed good discrimination in the clinical diagnosis cohort: area under the receiver operating curve 0.724,versus0.79 in the NIVO validation cohort. At one year post discharge, 41 of 89 clinical diagnosis patients had undertaken diagnostic spirometry; 33/41 had confirmation of airflow obstruction (FEV1/[F]VC &lt;0.7), meaning the diagnosis of COPD was incorrect in 19.5% of cases. These data support use of the NIVO score in patients with a “clinical diagnosis” of COPD. NIVO can help guide shared decision making, assess risk-adjusted outcomes by centre and challenge prognostic pessimism. Accurate diagnosis is critical to ensure acute and long-term treatment is optimised; this study highlights failings in follow up of such patients.