DIAGNOSIS AND MANAGEMENT OF ACUTE LUNG INJURY

Rare disorders have many faces: in silico characterization of rare disorder spectrum

Background

The diagnostic journey for many rare disease patients remains challenging despite use of latest genetic technological advancements. We hypothesize that some patients remain undiagnosed due to more complex diagnostic scenarios that are currently not considered in genome analysis pipelines. To better understand this, we characterized the rare disorder (RD) spectrum using various bioinformatics resources (e.g., Orphanet/Orphadata, Human Phenotype Ontology, Reactome pathways) combined with custom-made R scripts.

Results

Our in silico characterization led to identification of 145 borderline-common, 412 rare and 2967 ultra-rare disorders. Based on these findings and point prevalence, we would expect that approximately 6.53%, 0.34%, and 0.30% of individuals in a randomly selected population have a borderline-common, rare, and ultra-rare disorder, respectively (equaling to 1 RD patient in 14 people). Importantly, our analyses revealed that (1) a higher proportion of borderline-common disorders were caused by multiple gene defects and/or other factors compared with the rare and ultra-rare disorders, (2) the phenotypic expressivity was more variable for the borderline-common disorders than for the rarer disorders, and (3) unique clinical characteristics were observed across the disorder categories forming the spectrum.

Conclusions

Recognizing that RD patients who remain unsolved even after genome sequencing might belong to the more common end of the RD spectrum support the usage of computational pipelines that account for more complex genetic and phenotypic scenarios.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02217-9.

Feasibility of Continuous CO2 Removal with Hydrophilic Membranes at Low Blood Flow Rates

In the conventional treatment of acute respiratory distress syndrome (ARDS), high O2 concentrations and mechanical ventilation may damage the lung tissue. Extracorporeal membrane oxygenation limits damage, provides the needed O2 supply and improves survival of ARDS neonates, but not of adults. Hydrophilic membranes used in hemodialysis are more non-thrombogenic and biocompatible than those used in blood oxygenation, but their O2 transport capacity is not as high. In recent years, CO2 removal at low blood flow rates combined with apneic oxygenation and low frequency ventilation has proved promising in the treatment of ARDS. This approach makes O2 supply across ECMO membranes unnecessary; it also makes hydrophilic membranes candidates for extracorporeal CO2 removal to minimize anticoagulation and immune system activation. This paper reports on the in vitro capacity of hydrophilic polysulphone membranes to remove CO2 from carbonated pig blood into an oxygen-rich gas stream. Experiments were performed on clinical-size dialysis modules and their capacity to remove CO2 as a function of blood flow rate and membrane surface area was investigated. Membranes effectively removed CO2, more so at increasing blood flow rates and membrane surface areas, at rates of up to 15% of the CO2 metabolic production rate. The specific CO2 removal rate was comparable to that of blood oxygenators equipped with microporous hydrophobic membranes. It is concluded that CO2 removal from slowly flowing blood with hydrophilic membranes is feasible.

Lateralización como alternativa al decúbito prono estático en pacientes con SDRA

According to Phillips, Continuous Lateral Rotation (CLR) or Kinetic Therapy (KT) together with the technological advances obtain some important benefits in mechanically ventilated patients.

OBJECTIVE

Compare Static Prone Decubitus (PD) with DP in CRL.

PATIENTS AND METHODS

We analyzed 2 groups with a total of 41 patients in the period of January 1998 to April 2003. The DP group (25 patients) remained static and the lateral group (16 patients) in CLR every 2 h. The groups had 56 +/- 16 vs 64 +/- 17 years, 77 +/- 20 vs 71 +/- 23 kg and 24% vs 31% of survival, respectively.

RESULTS

We maintained the PD 37 +/- 30 vs 27 +/- 36 h for group 1 and 2. The response as Responders is 68% and 69%. pO2/FiO2 of supine pre-DP to supine post-DP is 79 +/- 21 to 146 +/- 68 versus 80 +/- 20 to 138 +/- 57 and pulmonary compliance 22 +/- 10 to 21 +/- 10 vs 31 +/- 10 to 32 +/- 9. Mean blood pressure of S to S was 87 +/- 16 to 85 +/- 15 vs 82 +/- 10 to 80 +/- 9, and mean Heart rate 108 +/- 21 to 95 +/- 24 vs 85 +/- 32 to 75 +/- 28. Complications by groups were: facial edema of 84% vs 63%, gastric retention 36% to 38%, vomiting/regurgitation 12% to 0%, epistaxis 8% to 31%. Pressure Sore (PS) Incidence decreased from 36% to 12%, together with seriousness.

CONCLUSION

We consider that lateralization if PD is a technique comparable to static PD on the respiratory and hemodynamics level. CLR in PD may prevent some complications.

Acute respiratory distress syndrome: underrecognition by clinicians and diagnostic accuracy of three clinical definitions

OBJECTIVE

To determine and compare the diagnostic accuracy of three clinical definitions of acute respiratory distress syndrome (ARDS): (1) the American-European consensus conference definition; (2) the lung injury score; and (3) a recently developed Delphi definition. A second objective was to determine the accuracy of clinical diagnoses of ARDS made in daily practice.

DESIGN

Independent comparison of autopsy findings with the daily status of clinical definitions, constructed with data abstracted retrospectively from medical records.

SETTING

Tertiary intensive care unit.

PATIENTS

One hundred thirty-eight patients from the period 1995 through 2001 who were autopsied after being mechanically ventilated.

INTERVENTIONS

Clinical ARDS diagnoses were determined daily without knowledge of autopsy results. Charts were reviewed for any mention of ARDS in the clinical notes. Autopsies were reviewed independently by two pathologists for the presence of diffuse alveolar damage. The sensitivity and specificity of the definitions were determined with use of diffuse alveolar damage at autopsy as the reference standard.

MEASUREMENTS AND MAIN RESULTS

Diffuse alveolar damage at autopsy was documented in 42 of 138 cases (30.4%). Only 20 of these 42 patients (47.6%) had any mention of ARDS in their chart. Sensitivities and specificities (95% confidence intervals) were as follows: American-European definition, 0.83 (0.72-0.95), 0.51 (0.41-0.61); lung injury score, 0.74 (0.61-0.87), 0.77 (0.69-0.86); and Delphi definition, 0.69 (0.55-0.83), 0.82 (0.75-0.90). Specificity was significantly higher for both the lung injury score and Delphi definition than for the American-European definition (p < .001 for both), whereas comparisons of sensitivity, which was higher for the American-European definition, were not significantly different (p = .34 and p = .07, respectively).

CONCLUSIONS

Acute respiratory distress syndrome appears underrecognized by clinicians in patients who die with this syndrome. In this population, the specificities of existing clinical definitions vary considerably, which may be problematic for clinical trials.

Development of a clinical definition for acute respiratory distress syndrome using the Delphi technique

PURPOSE

The objective of this study is to describe the implementation of formal consensus techniques in the development of a clinical definition for acute respiratory distress syndrome.

MATERIALS AND METHODS

A Delphi consensus process was conducted using e-mail. Sixteen panelists who were both researchers and opinion leaders were systematically recruited. The Delphi technique was performed over 4 rounds on the background of an explicit definition framework. Item generation was performed in round 1, item reduction in rounds 2 and 3, and definition evaluation in round 4. Explicit consensus thresholds were used throughout.

RESULTS

Of the 16 panelists, 11 actually participated in developing a definition that met a priori consensus rules on the third iteration. New incorporations in the Delphi definition include the use of a standardized oxygenation assessment and the documentation of either a predisposing factor or decreased thoracic compliance. The panelists rated the Delphi definition as acceptable to highly acceptable (median score, 6; range, 5-7 on a 7-point Likert scale).

CONCLUSIONS

We conclude that it is feasible to consider using formal consensus in the development of future definitions of acute respiratory distress syndrome. Testing of sensibility, reliability, and validity are needed for this preliminary definition; these test results should be incorporated into future iterations of this definition.

[Acute non-cardiogenic pulmonary edema secondary to hydrochlorothiazide therapy]

Several commonly prescribed drugs can cause acute non-cardiogenic pulmonary edema. A cause-effect relationship is usually difficult to establish because symptoms are not specific. We report a case of pulmonary edema induced by a common diuretic, hydrochlorothiazide. This complication can occur after a first dose of the drug or in patients who have been taking it with no side effects. Edema is due to an idiosyncratic reaction rather than an immune response. The clinical course is usually favorable over the first 24 hours with treatment of blood pressure and respiratory support. Given that severity increases with recurrence, we underline the importance of diagnosis in the first episode.

Fludarabine and cytarabine as a sequential infusion regimen for treatment of adults with recurrent, refractory or poor prognosis acute leukemia

We did a retrospective analysis on the safety and efficacy of sequential infusion fludarabine and cytosine arabinoside (ara-C) in treating refractory, recurrent or poor prognosis acute leukemia in adult patients. Forty-five adult patients with acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL) received a total of 68 courses of sequential continuous infusion of fludarabine for 2 days (total dose 71.5 mg/m(2) ) followed by 3 days of ara-C (total dose 7590 mg/m(2) ). Thirty-nine patients had refractory or recurrent disease, and six had other adverse prognostic features. Thirty-six patients had AML, seven had ALL, and two had CML in blastic phase. Complete remission was seen in 20 patients (44%), and partial remission in 5 patients (11%), giving a total response rate of 56%, similar for both AML and ALL. Duration of response to prior therapy did not affect the response rate. All 3 patients with Philadelphia chromosome positive ALL obtained complete remission. Median remission duration was 4.7 months (range 0.6-36.6), and median overall survival was 5.0 months (0.7-40+). Median overall survival was 10.1 months in responders. Pulmonary toxicity was seen in 8 patients, of whom 2 died from adult respiratory distress syndrome. No cardiac toxicity was observed, but 3 patients had transient cerebellar toxicity. Profound myelosuppression was seen in all patients. We conclude that the sequential infusion of fludarabine and ara-C is an effective non-cardiotoxic regimen for adults with refractory, recurrent or poor prognosis acute leukemia, may be particularly useful for resistant Philadelphia chromosome positive ALL, and may warrant further investigation in this subset. Pulmonary rather than neurological toxicity may be a unique side effect of the regimen.

Mechanisms of repair and remodeling following acute lung injury

At present, we largely lack the ability to correlate the clinical course of ARDS patients with potential factors involved in the biochemical and cellular basis of lung repair. This requires very large patient databases with measurement of many biochemical parameters. Important mechanistic determinants during the repair phase can be sought by correlation with late outcomes, but a large-scale cooperative effort among multiple centers with sharing of follow-up data and patient specimens is essential. We also lack detailed human histologic material from many phases of ARDS and, particularly, know little of the long-term morphologic impact of ARDS in survivors. Establishment of a national registry that follows ARDS survivors and that would seek their cooperation in advance in obtaining autopsy specimens when they die of other causes would be very valuable. Correlating the pathology with their pulmonary function during recovery would give important insights into the reasons for the different patterns of abnormal pulmonary functions. The factors that determine the success of repair are of critical importance in testing new ARDS treatment strategies. Would accelerating the resolution of alveolar edema alter the course of subsequent fibrosis and inflammation? Does surfactant replacement therapy--a costly proposition in adults with ARDS--lead to better long-term outcomes in survivors? How much should we worry about the use of high levels of oxygen for support of arterial partial pressure of oxygen? Is it better to accept hyperoxia to avoid pressure or volume trauma induced by mechanical ventilation with higher minute ventilations? These major management issues all may affect the success of the late repair and recovery process. Intervention trials need to examine the long-term physiologic and functional outcomes.

Critical care management of the patient with acute respiratory distress syndrome (ARDS). Part 2--A review of modes and strategies for ventilating the patient with poorly compliant lungs

Mechanical ventilation strategies for patients suffering from acute respiratory distress syndrome (ARDS) have traditionally relied on volume cycling. Due to the poor lung compliance characteristic of ARDS, these patients may be exposed to very high inspiratory pressures to achieve sufficient tidal volumes for adequate gas exchange. This greatly increases the risk of ventilator-induced lung injury associated with alveolar over-distention. The literature review explores the rationales behind alternative ventilation modes and strategies introduced to reduce the risk of ventilator-induced lung injury for the patient with ARDS.

Upregulation of collagen messenger RNA expression occurs immediately after lung damage

BACKGROUND

Mortality of ARDS still exceeds 50%. Though pulmonary fibrosis is a marker of severe prognosis in the evolution of ARDS, its onset is not yet established. Cardiopulmonary bypass (CPB), usually utilized in patients with a previously normal lung, can cause ARDS and often causes alveolar damage, the earliest lesion observed in ARDS, thus providing a unique opportunity to study the molecular mechanisms of fibrogenesis.

OBJECTIVE

To measure immediately after CPB, at the onset of alveolar damage, the expression of messenger RNAs (mRNAs) for collagen type I.

METHODS

Pre-CPB and post-CPB lung biopsy specimens were obtained from patients submitted to myocardial revascularization for coronary artery disease. Alveolar damage was characterized by comparison between before and after specimens and quantified by point counting of polymorphonuclear cells (PMN). Type I collagen mRNAs were quantified by scanning densitometry of Northern blot autoradiographs, corrected for RNA loading by 18S ribosomal RNA hybridization.

RESULTS

Alveolar damage was characterized by lung interstitial edema and by polymorphonuclear cell infiltration after CPB (PMN pre-CPB 0.010+/-0.004xPMN post-CPB 0.052+/-0.022; n=7; p=0.0017, t test). Type I collagen mRNA increased 91.1+/-68.2% (Ln pre-CPBxLn post-CPB; n=15; p<0.00001, t test) immediately after CPB (mean CPB time, 108.8+/-37.2 min).

CONCLUSION

Fibrogenesis, as measured at the molecular level, is a very early event following diffuse alveolar damage, attributable mainly to resident fibroblast activation.

Critical care management of the patient with acute respiratory distress syndrome (ARDS). Part 1: Pathophysiology and implications for mechanical ventilation

Acute respiratory distress syndrome (ADRS) is a severe, life-threatening consequence of certain pulmonary and systemic insults. It is thought to result from a dramatic change in the permeability of the alveolar-capillary membrane, allowing the movement of fluid and proteins into alveolar air spaces. These changes are followed by inactivation of surfactant, bringing about a significant alteration in lung compliance. It is common for the devastating changes to lung function in ARDS to necessitate the patient being supported by mechanical ventilation. However, the poor compliance of the ARDS-affected lung can greatly increase the risk of ventilator induced lung injury. This has led to a concern that traditional ventilation strategies may in fact be perpetuating the very conditions they attempt to compensate for.