Evaluation of the Acid-Base Status in Patients Admitted to the ICU Due to Severe COVID-19: Physicochemical versus Traditional Approaches

BACKGROUND

Stewart's approach is known to have better diagnostic accuracy for the identification of metabolic acid-base disturbances compared to traditional methods based either on plasma bicarbonate concentration ([HCO3-]) and anion gap (AG) or on base excess/deficit (BE). This study aimed to identify metabolic acid-base disorders using either Stewart's or traditional approaches in critically ill COVID-19 patients admitted to the ICU, to recognize potential hidden acid-base metabolic abnormalities and to assess the prognostic value of these abnormalities for patient outcome.

METHODS

This was a single-center retrospective study, in which we collected data from patients with severe COVID-19 admitted to the ICU. Electronical files were used to retrieve data for arterial blood gases, serum electrolytes, and proteins and to derive [HCO3-], BE, anion gap (AG), AG adjusted for albumin (AGadj), strong ion difference, strong ion gap (SIG), and SIG corrected for water excess/deficit (SIGcorr). The acid-base status was evaluated in each patient using the BE, [HCO3-], and physicochemical approaches.

RESULTS

We included 185 patients. The physicochemical approach detected more individuals with metabolic acid-base abnormalities than the BE and [HCO3-] approaches (p < 0.001), and at least one acid-base disorder was recognized in most patients. According to the physicochemical method, 170/185 patients (91.4%) had at least one disorder, as opposed to the number of patients identified using the BE 90/186 (48%) and HCO3 62/186 (33%) methods. Regarding the derived acid-base status variables, non-survivors had greater AGadj, (p = 0.013) and SIGcorr (p = 0.035) compared to survivors.

CONCLUSIONS

The identification of hidden acid-base disturbances may provide a detailed understanding of the underlying conditions in patients and of the possible pathophysiological mechanisms implicated. The association of these acid-base abnormalities with mortality provides the opportunity to recognize patients at increased risk of death and support them accordingly.

In-hospital and 6-month outcomes in patients with COVID-19 supported with extracorporeal membrane oxygenation (EuroECMO-COVID): a multicentre, prospective observational study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been widely used in patients with COVID-19, but uncertainty remains about the determinants of in-hospital mortality and data on post-discharge outcomes are scarce. The aims of this study were to investigate the variables associated with in-hospital outcomes in patients who received ECMO during the first wave of COVID-19 and to describe the status of patients 6 months after ECMO initiation.

METHODS

EuroECMO-COVID is a prospective, multicentre, observational study developed by the European Extracorporeal Life Support Organization. This study was based on data from patients aged 16 years or older who received ECMO support for refractory COVID-19 during the first wave of the pandemic-from March 1 to Sept 13, 2020-at 133 centres in 21 countries. In-hospital mortality and mortality 6 months after ECMO initiation were the primary outcomes. Mixed-Cox proportional hazards models were used to investigate associations between patient and management-related variables (eg, patient demographics, comorbidities, pre-ECMO status, and ECMO characteristics and complications) and in-hospital deaths. Survival status at 6 months was established through patient contact or institutional charts review. This study is registered with ClinicalTrials.gov, NCT04366921, and is ongoing.

FINDINGS

Between March 1 and Sept 13, 2020, 1215 patients (942 [78%] men and 267 [22%] women; median age 53 years [IQR 46-60]) were included in the study. Median ECMO duration was 15 days (IQR 8-27). 602 (50%) of 1215 patients died in hospital, and 852 (74%) patients had at least one complication. Multiorgan failure was the leading cause of death (192 [36%] of 528 patients who died with available data). In mixed-Cox analyses, age of 60 years or older, use of inotropes and vasopressors before ECMO initiation, chronic renal failure, and time from intubation to ECMO initiation of 4 days or more were associated with higher in-hospital mortality. 613 patients did not die in hospital, and 547 (95%) of 577 patients for whom data were available were alive at 6 months. 102 (24%) of 431 patients had returned to full-time work at 6 months, and 57 (13%) of 428 patients had returned to part-time work. At 6 months, respiratory rehabilitation was required in 88 (17%) of 522 patients with available data, and the most common residual symptoms included dyspnoea (185 [35%] of 523 patients) and cardiac (52 [10%] of 514 patients) or neurocognitive (66 [13%] of 512 patients) symptoms.

INTERPRETATION

Patient's age, timing of cannulation (<4 days vs ≥4 days from intubation), and use of inotropes and vasopressors are essential factors to consider when analysing the outcomes of patients receiving ECMO for COVID-19. Despite post-discharge survival being favourable, persisting long-term symptoms suggest that dedicated post-ECMO follow-up programmes are required.

FUNDING

None.

Paroxysmal atrial fibrillation with high vs. low arrhythmia burden: atrial remodelling and ablation outcome

AIMS

The relation between atrial tachyarrhythmia (ATA) burden in paroxysmal atrial fibrillation (AF), atrial remodelling, and efficacy of catheter ablation (CA) is unknown. We investigated whether high vs. low-burden paroxysmal AF patients have distinct clinical characteristics or electro-mechanical properties of the left atrium (LA) and whether burden impacts outcome of CA.

METHODS AND RESULTS

Atrial tachyarrhythmia burden, defined as the percentage of time spent in ATA, was assessed by insertable cardiac monitors in 105 patients before and after CA. Clinical characteristics and electro-mechanical properties of LA were compared between patients with high vs. low ATA burden. Catheter ablation efficacy was assessed by reduction in ATA burden and 1-year freedom from any ATA. Median ATA burden was 2.7% (highest tertile 9.3%). Clinical characteristics and electrical properties of LA (refractoriness, conduction velocity, low voltage) did not differ between high (≥9.3%) vs. low ATA burden (<9.3%) patients. High ATA burden patients had larger LA diameter (46.5 ± 6 vs. 42.5 ± 6mm, P < 0.01), volume (93.8 ± 22 vs. 80.4 ± 21mL, P = 0.01), and lower LA reservoir and contractile strain (19.7 ± 6 vs. 24.7 ± 6%, P < 0.01; 10.3 ± 3 vs. 12.8 ± 4%, P = 0.01). Catheter ablation reduced ATA burden by 100% (100-100) in both groups (P = 1.0). Freedom from ATA after CA was equally high (83% vs. 89%, P = 0.38).

CONCLUSION

Paroxysmal AF patients with high ATA burden have altered LA mechanical properties, reflected by larger size and impaired function. Despite mechanical remodelling of the atria, they are excellent responders to CA. Most likely the lack of fibrosis and/or advanced electrical remodelling explain why pulmonary veins remain the dominant trigger for AF in this patient cohort.

Complex Immune Dysregulation in COVID-19 Patients with Severe Respiratory Failure

Proper management of COVID-19 mandates better understanding of disease pathogenesis. The sudden clinical deterioration 7-8 days after initial symptom onset suggests that severe respiratory failure (SRF) in COVID-19 is driven by a unique pattern of immune dysfunction. We studied immune responses of 54 COVID-19 patients, 28 of whom had SRF. All patients with SRF displayed either macrophage activation syndrome (MAS) or very low human leukocyte antigen D related (HLA-DR) expression accompanied by profound depletion of CD4 lymphocytes, CD19 lymphocytes, and natural killer (NK) cells. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production by circulating monocytes was sustained, a pattern distinct from bacterial sepsis or influenza. SARS-CoV-2 patient plasma inhibited HLA-DR expression, and this was partially restored by the IL-6 blocker Tocilizumab; off-label Tocilizumab treatment of patients was accompanied by increase in circulating lymphocytes. Thus, the unique pattern of immune dysregulation in severe COVID-19 is characterized by IL-6-mediated low HLA-DR expression and lymphopenia, associated with sustained cytokine production and hyper-inflammation.

Persistent but reversible advanced atrio-ventricular block in a heart transplant man induced by dobutamine stress echocardiography

Dobutamine when used for stress echocardiography (DSE), it rarely causes transient atrio-ventricular (AV) block. We report a heart transplant patient with high cardiovascular risk who developed symptomatic advanced AV block during DSE which persisted after termination of dobutamine administration, necessitating pacemaker implantation. To our knowledge, this is the first published case of persistent high grade AV block in a heart transplant patient induced by DSE.

Variation of endothelium-related hemostatic factors during sepsis

OBJECTIVE

The thrombomodulin/protein C and VWF/ADAMTS-13 pathways are disturbed in sepsis and have been implicated in the coagulation disorders that characterize the septic syndrome. We aimed to assess the variation of these endothelial parameters during sepsis and their putative association with outcome, in critically ill, septic patients.

METHODS

We monitored 34 septic patients, 23 of whom improved (group A) while 11 deteriorated (group B). We assessed ADAMTS-13 levels, VWF activity, soluble thrombomodulin, and protein C activity upon admission to the ICU (time point 0) and at the time of a change in the clinical condition (remission or deterioration, time point 1).

RESULTS

In group A, thrombomodulin and VWF increased at time point 1 compared to time point 0 (P = 0.011, P = 0.028, respectively). In group B, protein C and ADAMTS-13 significantly decreased (P = 0.023, P = 0.026, respectively), while VWF, VWF/ADAMTS-13 ratio, and the thrombomodulin/protein C ratio increased (P = 0.02, P = 0.002, P = 0.01, respectively). Protein C (> or ≤17%) and ADAMTS-13 percentage difference (> or ≤22%) were independently associated with sepsis outcome among the endothelial variables tested.

CONCLUSIONS

An ongoing endothelial/hemostatic disorder was established during sepsis, observed even at clinical improvement. Among the variables tested, protein C and ADAMTS-13 change were associated with outcome.

A cytologic diagnosis of BRAFV600E Erdheim-Chester disease on pericardial fluid

We report the case of a 74-year-old woman admitted to the emergency unit for resting dyspnea. Clinical presentation, cardiac MRI and echocardiography were consistent with cardiac tamponade requiring emergency pericardiocentesis. Cytologic examination of the pericardial fluid revealed the presence of CD68^pos CD1a^neg S100^neg foamy histiocytes (Fig. 1). Additional investigations complied with the diagnosis of Erdheim-Chester histiocytosis. Treatment with αIFN was initiated but the patient developed severe neutropenia that contraindicated further administration. The detection of BRAF^V600E mutation on histiocytes isolated from the pericardial liquid and CNS involvement (cerebral masses) prompted the administration of vemurafenib, a selective BRAF^V600E kinase inhibitor. Four months after the initiation of low-dose vemurafenib, pericarditis almost resolved and cerebral masses decreased by 50% (Fig. 2). To our knowledge, analysis of pericardial fluid allowing the diagnosis of Erdheim-Chester disease and the detection of the BRAF^V600E mutation has in fact been rarely described in the literature. This case report and the successful evolution under vemurafenib also support the use of BRAF^V600E inhibitors in αIFN-intolerant patients with BRAF^V600E mutation, particularly in case of heart and central nervous system involvement.

Respiratory mechanics in brain injury: A review

Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmitters, or autonomic system dysfunction. Mechanical ventilation, an essential component of life support in brain-damaged patients (BD), may be an additional traumatic factor to the already injured or susceptible to injury lungs of these patients thus worsening lung injury, in case that non lung protective ventilator settings are applied. Measurement of respiratory mechanics in BD patients, as well as assessment of their evolution during mechanical ventilation, may lead to preclinical lung injury detection early enough, allowing thus the selection of the appropriate ventilator settings to avoid ventilator-induced lung injury. The aim of this review is to explore the mechanical properties of the respiratory system in BD patients along with the underlying mechanisms, and to translate the evidence of animal and clinical studies into therapeutic implications regarding the mechanical ventilation of these critically ill patients.

A case of imported Middle East Respiratory Syndrome coronavirus infection and public health response, Greece, April 2014

On 18 April 2014, a case of Middle East Respiratory Syndrome coronavirus (MERS-CoV) infection was laboratory confirmed in Athens, Greece in a patient returning from Jeddah, Saudi Arabia. Main symptoms upon initial presentation were protracted fever and diarrhoea, during hospitalisation he developed bilateral pneumonia and his condition worsened. During 14 days prior to onset of illness, he had extensive contact with the healthcare environment in Jeddah. Contact tracing revealed 73 contacts, no secondary cases had occurred by 22 April.

Factor XIII deficiency as a potential cause of supratentorial haemorrhage after posterior fossa surgery

BACKGROUND

Postoperative intracranial haemorrhage can be a dramatic event, carrying significant morbidity and mortality. Bleeding at sites remote from the operation area represents a small percentage of haemorrhages whose aetiology remains unclear (Harders et al. Acta Neurochir (Wien) 74(1-2):57-60, 1985).

AIM

We present the case of a 60-year-old patient who underwent posterior fossa craniotomy for the removal of a space-occupying lesion and suffered supratentorial haemorrhage soon after the operation.

RESULTS

A thorough postoperative investigation revealed low levels of factor XIII (FXIII), the factor mainly responsible for fibrin clot stabilisation.

CONCLUSION

We suggest that reduced FXIII activity may be an important but preventable predisposing factor to remote postoperative haemorrhage in neurosurgical patients.

Emergency percutaneous tracheostomy in a severely burned patient with upper airway obstruction and circulatory failure

Airway inaccessibility is one of the most dreaded situations in emergency medicine. Surgical tracheostomy is not indicated in emergency situations because it takes a long time and can result in death if respiratory support cannot be provided during the procedure. Emergency percutaneous tracheostomy (PCT) was widely regarded as absolutely counterindicated. Recently, however, a number of studies have appeared on the safety and feasibility of PCT in situations regarded as presenting relative contraindications. We describe the life-saving action of Griggs' PCT in a patient with upper airway obstruction resulting from burns, smoke injuries, and unsuccessful tracheal intubation attempts. Emergency PCT using the Griggs technique was immediately performed without aseptic care, and a 9-mm internal diameter tracheostomy tube was successfully inserted in less than one minute. Griggs' PCT is a quick technique that secures an airway when tracheal intubation fails. The feasibility - in selected cases - of using an emergency Griggs' PCT, in experienced hands, rather than cricothyroidotomy or surgical tracheostomy, is recommended.