Acute kidney injury in stable COPD and at exacerbation

Impact of AKI on metabolic compensation for respiratory acidosis in ICU patients with AECOPD

PURPOSE

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) can result in severe respiratory acidosis. Metabolic compensation is primarily achieved by renal retention of bicarbonate. The extent to which acute kidney injury (AKI) impairs the kidney's capacity to compensate for respiratory acidosis remains unclear.

MATERIALS AND METHODS

This retrospective analysis covers clinical data between January 2009 and December 2021 for 498 ICU patients with AECOPD and need for respiratory support.

RESULTS

278 patients (55.8%) presented with or developed AKI. Patients with AKI exhibited higher 30-day-mortality rates (14.5% vs. 4.5% p = 0.001), longer duration of mechanical ventilation (median 90 h vs. 14 h; p = 0.001) and more severe hypercapnic acidosis (pH 7.23 vs. 7.28; pCO2 68.5 mmHg vs. 61.8 mmHg). Patients with higher AKI stages exhibited lower HCO3-/pCO2 ratios and did not reach expected HCO3- levels. In a mixed model analysis with random intercept per patient we analyzed the association of pCO2 (independent) and HCO3- (dependent variable). Lower estimates for averaged change in HCO3- were observed in patients with more severe AKI.

CONCLUSION

AKI leads to poor outcomes and compromises metabolic compensation of respiratory acidosis in ICU patients with AECOPD. While buffering agents may aid compensation for severe AKI, their use should be approached with caution.

Prognostic Value of Leukocyte-Based Risk Model for Acute Kidney Injury Prediction in Critically Ill Acute Exacerbation of Chronic Obstructive Pulmonary Disease Patients

Purpose

Acute kidney injury (AKI) is a common complication of acute exacerbation of chronic obstructive pulmonary disease (AECOPD), and inflammation is the potential link between AKI and AECOPD. However, little is known about the incidence and risk stratification of AKI in critically ill AECOPD patients. In this study, we aimed to establish risk model based on white blood cell (WBC)-related indicators to predict AKI in critically ill AECOPD patients.

Material and Methods

For the training cohort, data were taken from the Medical Information Mart for eICU Collaborative Research Database (eICU-CRD) database, and for the validation cohort, data were taken from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. The study employed logistic regression analysis to identify the major predictors of WBC-related biomarkers on AKI prediction. Subsequently, a risk model was developed by multivariate logistic regression, utilizing the identified significant indicators.

Results

Finally, 3551 patients were enrolled in training cohort, 926 patients were enrolled in validation cohort. AKI occurred in 1206 (33.4%) patients in training cohort and 521 (56.3%) patients in validation cohort. According to the multivariate logistic regression analysis, four WBC-related indicators were finally included in the novel risk model, and the risk model had a relatively good accuracy for AKI in the training set (C-index, 0.764, 95% CI 0.749-0.780) as well as in the validation set (C-index, 0.738, 95% CI: 0.706-0.770). Even after accounting for other models, the critically ill AECOPD patients in the high-risk group (risk score > 3.44) still showed an increased risk of AKI (odds ratio: 4.74, 95% CI: 4.07-5.54) compared to those in low-risk group (risk score ≤ 3.44). Moreover, the risk model showed outstanding calibration capability as well as therapeutic usefulness in both groups for AKI and ICU mortality and in-hospital mortality of critical ill AECOPD patients.

Conclusion

The novel risk model showed good AKI prediction performance. This risk model has certain reference value for the risk stratification of AECOPD complicated with AKI in clinically.

Hemodynamic effects of positive end-expiratory pressure

PURPOSE OF REVIEW

Positive end-expiratory pressure (PEEP) is required in the Berlin definition of acute respiratory distress syndrome and is a cornerstone of its treatment. Application of PEEP increases airway pressure and modifies pleural and transpulmonary pressures according to respiratory mechanics, resulting in blood volume alteration into the pulmonary circulation. This can in turn affect right ventricular preload, afterload and function. At the opposite, PEEP may improve left ventricular function, providing no deleterious effect occurs on the right ventricle.

RECENT FINDINGS

This review examines the impact of PEEP on cardiac function with regards to heart-lung interactions, and describes its consequences on organs perfusion and function, including the kidney, gut, liver and the brain. PEEP in itself is not beneficious nor detrimental on end-organ hemodynamics, but its hemodynamic effects vary according to both respiratory mechanics and association with other hemodynamic variables such as central venous or mean arterial pressure. There are parallels in the means of preventing deleterious impact of PEEP on the lungs, heart, kidney, liver and central nervous system.

SUMMARY

The quest for optimal PEEP settings has been a prominent goal in ARDS research for the last decades. Intensive care physician must maintain a high degree of vigilance towards hemodynamic effects of PEEP on cardiac function and end-organs circulation.

Hospitalized acute exacerbation in chronic obstructive pulmonary disease - impact on long-term renal outcomes

INTRODUCTION

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a common and preventable event in patients with chronic obstructive pulmonary disease (COPD). Data regarding the impact of AECOPD on short- and long-term renal outcomes are lacking.

METHODS

We included all COPD patients who were followed at Queen Mary Hospital (QMH) in year 2015 and reviewed their clinical/renal outcomes in subsequent five years. Relationships between AECOPD and adverse renal outcomes were evaluated.

RESULTS

371 COPD patients were included. 169 patients had hospitalized AECOPD in past one year (HAE group) while 202 patients did not (non-HAE group). 285 patients (76.8%) had renal progression/death and 102 (27.5%) patients developed acute kidney injury (AKI). HAE group showed a more rapid eGFR decline than non-HAE group (-4.64 mL/min/1.73m2/year vs. -2.40 mL/min/1.73m2/year, p = 0.025). HAE group had significantly higher risk for renal progression/death at 5 years [adjusted OR (aOR) 2.380 (95% CI = 1.144-4.954), p = 0.020]. The frequency of hospitalized AECOPD in past 3 years, any AECOPD in past 3 years, hospitalized AECOPD in past 3 years were also predictive of renal progression/death at 5 years [aOR were 1.176 (95% CI = 1.038- 1.331), 2.998 (95% CI = 1.438-6.250) and 2.887 (95% CI = 1.409-5.917) respectively; p = 0.011, 0.003 and 0.004]. HAE group also showed significantly higher risk of AKI [adjusted HR (aHR) 2.430; 95% CI = 1.306-4.519, p = 0.005].

CONCLUSIONS

AECOPD, in particular HAE, was associated with increased risk of renal progression/death and AKI. Prevention of AECOPD, especially HAE, may potentially improve short- and long-term renal outcomes in COPD patients.

Machine learning reveals sex differences in clinical features of acute exacerbation of chronic obstructive pulmonary disease: A multicenter cross-sectional study

Introduction

Intrinsically, chronic obstructive pulmonary disease (COPD) is a highly heterogonous disease. Several sex differences in COPD, such as risk factors and prevalence, were identified. However, sex differences in clinical features of acute exacerbation chronic obstructive pulmonary disease (AECOPD) were not well explored. Machine learning showed a promising role in medical practice, including diagnosis prediction and classification. Then, sex differences in clinical manifestations of AECOPD were explored by machine learning approaches in this study.

Methods

In this cross-sectional study, 278 male patients and 81 female patients hospitalized with AECOPD were included. Baseline characteristics, clinical symptoms, and laboratory parameters were analyzed. The K-prototype algorithm was used to explore the degree of sex differences. Binary logistic regression, random forest, and XGBoost models were performed to identify sex-associated clinical manifestations in AECOPD. Nomogram and its associated curves were established to visualize and validate binary logistic regression.

Results

The predictive accuracy of sex was 83.930% using the k-prototype algorithm. Binary logistic regression revealed that eight variables were independently associated with sex in AECOPD, which was visualized by using a nomogram. The AUC of the ROC curve was 0.945. The DCA curve showed that the nomogram had more clinical benefits, with thresholds from 0.02 to 0.99. The top 15 sex-associated important variables were identified by random forest and XGBoost, respectively. Subsequently, seven clinical features, including smoking, biomass fuel exposure, GOLD stages, PaO2, serum potassium, serum calcium, and blood urea nitrogen (BUN), were concurrently identified by three models. However, CAD was not identified by machine learning models.

Conclusions

Overall, our results support that the clinical features differ markedly by sex in AECOPD. Male patients presented worse lung function and oxygenation, less biomass fuel exposure, more smoking, renal dysfunction, and hyperkalemia than female patients with AECOPD. Furthermore, our results also suggest that machine learning is a promising and powerful tool in clinical decision-making.

Organ Crosstalk in Acute Kidney Injury: Evidence and Mechanisms

Acute kidney injury (AKI) is becoming a public health problem worldwide. AKI is usually considered a complication of lung, heart, liver, gut, and brain disease, but recent findings have supported that injured kidney can also cause dysfunction of other organs, suggesting organ crosstalk existence in AKI. However, the organ crosstalk in AKI and the underlying mechanisms have not been broadly reviewed or fully investigated. In this review, we summarize recent clinical and laboratory findings of organ crosstalk in AKI and highlight the related molecular mechanisms. Moreover, their crosstalk involves inflammatory and immune responses, hemodynamic change, fluid homeostasis, hormone secretion, nerve reflex regulation, uremic toxin, and oxidative stress. Our review provides important clues for the intervention for AKI and investigates important therapeutic potential from a new perspective.

A Novel Predictive Model for Hospital Survival in Patients who are Critically Ill with Dialysis-Dependent AKI: A Retrospective Single-Center Exploratory Study

BACKGROUND

Mortality of patients who are critically ill with AKI initiated on RRT is very high. Identifying modifiable and unmodifiable clinical variables at dialysis start that are associated with hospital survival can help, not only in prognostication, but also in clinical triaging.

METHODS

A retrospective observational study was conducted on patients with AKI-D who were initiated on RRT in the medical and surgical intensive care units (ICUs) of a high-acuity academic medical center from January 2010 through December 2015. We excluded patients with suspected poisoning, ESKD, stage 5 CKD not on dialysis, or patients with AKI-D initiated on RRT outside of the ICU setting. The primary outcome was in-hospital mortality.

RESULTS

Of the 416 patients who were critically ill with AKI-D admitted to the medical (38%), surgical (41%), and cardiac (21%) ICUs, with nearly 75% on artificial organ support, the mean age 62.1±14.8 years, mean SOFA score was 11.8±4.3, dialysis was initiated using continuous RRT in 261 (63%) and intermittent hemodialysis in 155 (37%) patients. Incidence of survival to hospital discharge was 48%. Using multivariable logistic regression with stepwise backward elimination, a prognostic model was created that included the variables age, CKD, COPD, admission, and within 24 hours of the start SOFA score, refractory hyperkalemia and uremic encephalopathy as dialysis indications, BUN >100 mg/dl, serum creatinine, serum lactate, serum albumin, CRRT as initial modality, severe volume overload, and abdominal surgery. The model exhibited good calibration (goodness of fit test, P=0.83) and excellent discrimination (optimism-corrected C statistic 0.93).

CONCLUSIONS

In this single-center, diverse, critically ill AKI-D population, a novel prognostic model that combined widely used ICU scores, clinical and biochemical data at dialysis start, and dialysis indication and modality, robustly predicted short-term survival. External validation is needed to prove the generalizability of the study findings.

Interaction of Acute Respiratory Failure and Acute Kidney Injury on in-Hospital Mortality of Patients with Acute Exacerbation COPD

Purpose

Both acute respiratory failure (ARF) and acute kidney injury (AKI) are two common complications in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Moreover, both ARF and AKI are reported as increasing the risk of mortality of patients with AECOPD. However, the interaction of ARF and AKI on the mortality of patients with AECOPD remains unknown. Therefore, the aim of this study is to investigate the joint effect of ARF and AKI on in-hospital mortality in AECOPD patients.

Patients and Methods

We performed a retrospective, observational cohort study of data from Nanjing First Hospital. The effect of AKI and ARF on in-hospital mortality was assessed using a multivariate logistic regression model. Additive interaction was assessed with the relative excess risk due to interaction.

Results

A total of 1647 participants were enrolled. ARF and AKI occurred in 515 (31.3%) and 357 (21.7%) patients, respectively. Overall, in-hospital mortality was 5.7%. The in-hospital mortality of the neither ARF nor AKI group, the ARF only group, the AKI only group, and both the ARF and AKI group were 0.8%, 7.0%, 7.5%, and 29.9%, respectively. After multivariate logistic regression analysis, the independent factors for in-hospital death included: albumin (OR 0.88, 95% CI 0.83–0.93, P < 0.001), ARF only (OR 8.53, 95% CI 3.64–19.99, P < 0.001), AKI only (OR 8.99, 95% CI 3.58–22.55, P < 0.001), and both ARF and AKI (OR 39.13, 95% CI 17.02–89.97, P < 0.001). The relative excess risk due to interaction was 22.62 (95% CI, 0.31 to 44.93), the attributable proportion due to interaction was 0.59 (95% CI, 0.36 to 0.79), and the synergy index was 2.46 (95% CI, 1.44 to 4.20), indicating ARF and AKI had a significant synergic effect on in-hospital mortality.

Conclusion

ARF and AKI had a synergistic effect on in-hospital mortality in AECOPD patients.

2021 Guideline for the Management of COPD Exacerbations: Emergency Medicine Association of Turkey (EMAT) / Turkish Thoracic Society (TTS) Clinical Practice Guideline Task Force

Chronic obstructive pulmonary disease (COPD) is an important public health problem that manifests with exacerbations and causes serious mortality and morbidity in both developed and developing countries. COPD exacerbations usually present to emergency departments, where these patients are diagnosed and treated. Therefore, the Emergency Medicine Association of Turkey and the Turkish Thoracic Society jointly wanted to implement a guideline that evaluates the management of COPD exacerbations according to the current literature and provides evidence-based recommendations. In the management of COPD exacerbations, we aim to support the decision-making process of clinicians dealing with these patients in the emergency setting.

Acute kidney injury following transcatheter edge-to-edge mitral valve repair: A systematic review and meta-analysis

BACKGROUND

Aim of this study was to perform a systematic review a meta-analysis of the literature in order to identify predictors of acute kidney injury (AKI) in patients with mitral regurgitation (MR) undergoing transcatheter edge-to-edge repair (TEER) and assess its effect on in-hospital outcomes and mortality. Although iodinated contrast is not typically used in TEER, these patients are still at risk for developing AKI.

METHODS

Studies reporting on the effect of incident AKI on mortality following TEER for MR were included. Random-effects meta-analysis was performed, comparing clinical outcomes between the patients with or without incident AKI.

RESULTS

Six studies including a total of 2057 patients (377 AKI and 1680 No-AKI) were included and analyzed. AKI was significantly associated with 30-day mortality after TEER (Odds ratio (OR): 8.06; 95% CI: 3.20, 20.30, p < 0.01; I² = 18.4%) and all-cause mortality over a mean follow-up time of 30 months (Hazard ratio (HR): 2.48; 95% CI: 1.89, 3.24, p < 0.01; I² = 23.7%). AKI after TEER was associated with prolonged hospitalization (Mean difference (in days): 1.41; 95% CI: 0.52, 2.31, p < 0.01; I² = 82.4%). Stage 4 chronic kidney disease (CKD), device failure and history of chronic obstructive pulmonary disease (COPD) were significant predictors of AKI following TEER (CKD stage 4: OR: 2.38; 95% CI: 1.18, 4.78, p = 0.02; I² = 0.0%; Device failure: OR: 3.15; 95% CI: 1.94, 5.12, p < 0.01; I² = 0.0%; COPD: OR: 1.92; 95% CI: 1.16, 3.17; I² = 26.7%).

CONCLUSIONS

Our findings highlight the renal vulnerability of the TEER population to renal injury and the associated deterioration in clinical outcomes and survival.

Acute Beetroot Juice Ingestion Does Not Alter Renal Hemodynamics during Normoxia and Mild Hypercapnia in Healthy Young Adults

Arterial hypercapnia reduces renal perfusion. Beetroot juice (BRJ) increases nitric oxide bioavailability and may improve renal blood flow. We tested the hypothesis that acute consumption of BRJ attenuates both decreases in blood velocity and increases in vascular resistance in the renal and segmental arteries during acute hypercapnia. In fourteen healthy young adults, blood velocity and vascular resistance were measured with Doppler ultrasound in the renal and segmental arteries during five minutes of breathing a carbon dioxide gas mixture (CO₂) before and three hours after consuming 500 mL of BRJ. There was no difference between pre- and post-BRJ consumption in the increase in the partial pressure of end-tidal CO₂ during CO₂ breathing (pre: +4 ± 1 mmHg; post: +4 ± 2 mmHg, p = 0.4281). Segmental artery blood velocity decreased during CO₂ breathing in both pre- (by −1.8 ± 1.9 cm/s, p = 0.0193) and post-BRJ (by −2.1 ± 1.9 cm/s, p = 0.0079), but there were no differences between pre- and post-consumption (p = 0.7633). Segmental artery vascular resistance increased from room air baseline during CO₂ at pre-BRJ consumption (by 0.4 ± 0.4 mmHg/cm/s, p = 0.0153) but not post-BRJ (p = 0.1336), with no differences between pre- and post-consumption (p = 0.7407). These findings indicate that BRJ consumption does not attenuate reductions in renal perfusion during acute mild hypercapnia in healthy young adults.

Role of the IL-33/ST2 axis in cigarette smoke-induced airways remodelling in chronic obstructive pulmonary disease

BACKGROUND

Efficient therapy and potential prophylaxis are confounded by current ignorance of the pathogenesis of airway remodelling and blockade in COPD.

OBJECTIVE

To explore the role of the IL-33/ST2 axis in cigarette smoke (CS) exposure-induced airways remodelling.

METHODS

C57BL/6, BALB/c and IL-1RL1 -/- mice exposed to CS were used to establish an animal surrogate of COPD (air-exposed=5~8, CS-exposed=6~12). Hallmarks of remodelling were measured in mice. Cigarette smoke extract (CSE)-induced proliferation and protein production in vitro by fibroblasts in the presence of anti-interleukin-33 (anti-IL-33) or hST2 antibodies were measured. Expression of IL-33 and ST2 and other remodelling hallmarks were measured, respectively, in bronchoalveolar lavage fluid (BALF) (controls=20, COPD=20), serum (controls=59, COPD=90) and lung tissue sections (controls=11, COPD=7) from patients with COPD and controls.

RESULTS

Wild-type mice exposed to CS elevated expression of hallmarks of tissue remodelling in the lungs and also in the heart, spleen and kidneys, which were significantly abrogated in the IL-1RL1 -/- mice. Fibroblasts exposed to CSE, compared with control, exhibited early cellular translocation of IL-33, accompanied by proliferation and elevated protein synthesis, all inhabitable by blockade of IL-33/ST2 signalling. Expression of IL-33 and ST2 and hallmarks of tissue remodelling were significantly and proportionally elevated in BALF, serum and tissue samples from patients with COPD.

CONCLUSIONS

Exposure to CS induces remodelling changes in multiple organs. The data support the hypothesis that CS-induced lung collagen deposition is at least partly a result of CS-induced IL-33 translocation and release from local fibroblasts.

Serum cystatin C: A potential predictor for hospital-acquired acute kidney injury in patients with acute exacerbation of COPD

Hospital-acquired acute kidney injury (HA-AKI) is associated with poor prognosis. In this study, we evaluated whether serum cystatin C on admission could predict AKI in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The retrospective study was conducted using data on adult inpatients with AECOPD from January 2014 to January 2017. A total of 1035 patients were included, among which 79 (7.6%) with HA-AKI were identified. Univariate and multivariate logistic regression analyses were used to investigate predictors of HA-AKI in patients with AECOPD. HA-AKI was associated with poor prognosis, and patients with HA-AKI had higher inpatient mortality (34.2% vs. 2.6%, p < 0.001). Furthermore, after adjusting for confounders, HA-AKI was an independent risk factor for inpatient mortality for patients with AECOPD (odds ratio (OR) 11.02; 95% confidence interval (CI) 4.77–25.45; p < 0.001). Four independent risk factors for HA-AKI (age, levels of urea and cystatin C, and platelet count on admission) were identified in patients with AECOPD. Cystatin C (OR 5.22; 95% CI 2.49–10.95; p < 0.001) was a significant independent predictor of AKI in patients with AECOPD. HA-AKI in patients with AECOPD could be identified with a sensitivity of 73.5% and a specificity of 75.9% (area under the curve (AUC) = 0.803, 95% CI 0.747–0.859) by cystatin C level (cutoff value = 1.3 mg/L) and with a sensitivity of 75.9% and a specificity of 82.0% (AUC = 0.853, 95% CI 0.810–0.896) using a model comprising all significant predictors. Serum cystatin C has the potential for use to predict the risk of HA-AKI in patients with AECOPD.

Incidence, Risk Factors, and Prognostic Implications of Acute Kidney Injury in Patients with Acute Exacerbation of COPD

Purpose

Little is known about the incidence, risk factors, and prognostic implications of acute kidney injury (AKI) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in China. In this study, we investigated the incidence, risk factors, and short-term outcomes of AKI in these patients.

Patients and Methods

We analyzed the records of 1768 patients admitted to Nanjing First Hospital with a principal diagnosis of AECOPD. Of these, 377 patients had AKI.

Results

AKI occurred in 377 patients (21%). Independent risk factors for AKI in patients with AECOPD were advanced age, coronary artery disease, anemia, cancer, chronic kidney disease, hypercapnic encephalopathy, acute respiratory failure, and mechanical ventilation. Patients with AKI had worse prognostic implications and were more likely to require mechanical ventilation (38.7% vs 19.1%, P<0.001); non-invasive mechanical ventilation (38.2% vs 18.9%, P<0.001); invasive mechanical ventilation (18.3% vs 3.1%, P<0.001); intensive care unit (ICU) admission (33.7% vs 12.9%, P<0.001); had a longer ICU stay (9 days vs 8 days, P=0.033) and longer hospitalization (13 days vs 10 days, P<0.001); and higher in-hospital mortality (18.0% vs 2.7%, P<0.001) than those without AKI. Multivariable analysis indicated that compared to patients without AKI, those with stage 1, 2, or 3 AKI had a 1.9-fold, 2.1-fold, or 6.0-fold increased risk of in-hospital death, respectively.

Conclusion

AKI is common in patients with AECOPD requiring hospitalization. Patients with AKI have worse short-term outcomes. Thus, AKI may be a prognostic predictor of patient survival.

Aspects extrapulmonaires des exacerbations de bronchopneumopathie chronique obstructive

La bronchopneumopathie chronique obstructive (BPCO) est une maladie systémique aux multiples atteintes, émaillée d’exacerbations. L’inflammation, l’hypoxémie, les troubles de la coagulation et les perturbations des interactions coeur–poumon expliquent en partie les atteintes non pulmonaires observées notamment lors d’exacerbations aiguës. Les événements cardiovasculaires sont la première cause de mortalité des patients BPCO, et leur recrudescence est observée pendant plusieurs semaines après une exacerbation. Aux urgences, la prise en charge des patients en exacerbation de BPCO repose donc en plus du support ventilatoire sur une bonne évaluation des potentielles pathologies associées telles que l’insuffisance cardiaque, l’ischémie myocardique, l’insuffisance rénale ou encore la maladie thromboembolique. Cette évaluation globale permet d’adapter les thérapeutiques parfois délétères sur la fonction cardiaque ou l’équilibre acide−base et de prendre en compte le risque extrapulmonaire dans le choix du parcours de soins du patient. Dans cette mise au point, nous abordons quelques explications physiologiques des multiples perturbations observées au cours de l’exacerbation de BPCO, et proposons une vision globale de l’évaluation de ces patients admis pour une dyspnée ou un autre motif pouvant être en rapport avec la BPCO.

Acute kidney injury in hospitalized patients with nonexacerbated chronic obstructive pulmonary disease

Background

The epidemiology of acute kidney injury (AKI) in nonexacerbated chronic obstructive pulmonary disease (NECOPD) patients is unknown. This study investigated the factors associated with AKI and the association between AKI and in-hospital mortality in the hospitalized NECOPD population.

Methods

The electronic medical records of 2897 patients hospitalized with NECOPD were analyzed retrospectively. Demographic information, medicine used before AKI, diagnosis records and laboratory data were collected. AKI was classified as community-acquired (CA-) or hospital-acquired (HA-) AKI according to the serum creatinine criteria. Risk factors for HA-AKI and in-hospital mortality were analyzed by logistic regression analyses. To avoid an interaction between cor pulmonale and AKI, the association between AKI and in-hospital morality was further analyzed with cor pulmonale stratification.

Results

The incidence rates of CA- and HA-AKI were 7.1 and 12.0%, respectively. Increased age, female sex, cor pulmonale comorbidity, chronic kidney disease stage, diuretic and glycopeptide use before AKI and iodine-containing contrast medium exposure were independently associated with HA-AKI. A total of 5.7% of the patients died. After adjustment for age, sex, cor pulmonale, chronic kidney disease, Charlson comorbidity index score (without renal disease) and hemoglobin level, HA-AKI was an independent risk factor for in-hospital mortality [OR 13.909 (95% CI 8.699–22.238) in non-cor pulmonale subgroup; OR 26.604 (95% CI 12.166–58.176) in cor pulmonale subgroup], whereas CA-AKI was not.

Conclusions

AKI is common in the NECOPD population. Diuretics and contrast media are associated with HA-AKI in this population. The patients with HA-AKI have a higher mortality risk than the patients without AKI.

Diagnostics, Risk Factors, Treatment and Outcomes of Acute Kidney Injury in a New Paradigm

Acute kidney injury (AKI) is a common clinical condition among patients admitted in the hospitals. The condition is associated with both increased short-term and long-term mortality. With the development of a standardized definition for AKI and the acknowledgment of the impact of AKI on patient outcomes, there has been increased recognition of AKI. Two advances from past decades, the usage of computer decision support and the discovery of AKI biomarkers, have the ability to advance the diagnostic method to and further management of AKI. The increasingly widespread use of electronic health records across hospitals has substantially increased the amount of data available to investigators and has shown promise in advancing AKI research. In addition, progress in the finding and validation of different forms of biomarkers of AKI within diversified clinical environments and has provided information and insight on testing, etiology and further prognosis of AKI, leading to future of precision and personalized approach to AKI management. In this this article, we discussed the changing paradigms in AKI: from mechanisms to diagnostics, risk factors, and management of AKI.

Association of acute kidney injury with readmissions after hospitalization for acute exacerbation of chronic obstructive pulmonary disease: a population-based study

Background

Little is known about the relationship between acute kidney injury (AKI) and outcomes after acute exacerbation of chronic obstructive pulmonary disease (AECOPD). We aimed to investigate associations between AKI and readmission risks after hospitalization for AECOPD.

Methods

A retrospective, population-based cohort study using State Inpatient Databases from seven U.S. states (Arkansas, California, Florida, Iowa, Nebraska, New York, and Utah) from 2010 through 2013. We identified all adults (aged ≥40 years) hospitalized for AECOPD during the study period. Among them, we further identified patients with a concurrent diagnosis of new AKI. The outcome measures were any-cause readmissions within 30 days and 90 days after hospitalization for AECOPD. To determine associations between AKI and readmission risk, we constructed Cox proportional hazards models examining the time-to-readmission. We also identified the primary reason of readmission.

Results

We identified 356,990 patients hospitalized for AECOPD. The median age was 71 years and 41.9% were male. Of these, 24,833 (7.0%) had a concurrent diagnosis of AKI. Overall, patients with AKI had significantly higher risk of 30-day all-cause readmission compared to those without AKI (hazard ratio 1.47; 95% CI 1.43–1.51; P < 0.001). Likewise, patients with AKI had significantly higher risk of 90-day all-cause readmission (hazard ratio 1.35; 95% CI 1.32–1.38; P < 0.001). These associations remained significant after adjustment for confounders (both P < 0.05). Additionally, patients with AKI were likely to be readmitted for non-respiratory reasons including sepsis, acute renal failure, and congestive heart failure.

Conclusions

Among patients hospitalized for AECOPD, patients with AKI were at higher risk of 30-day and 90-day readmission, particularly with non-respiratory reasons.

Renal and segmental artery hemodynamic response to acute, mild hypercapnia

Profound increases (>15 mmHg) in arterial carbon dioxide (i.e., hypercapnia) reduce renal blood flow. However, a relatively brief and mild hypercapnia can occur in patients with sleep apnea or in those receiving supplemental oxygen therapy during an acute exacerbation of chronic obstructive pulmonary disease. We tested the hypothesis that a brief, mild hypercapnic exposure increases vascular resistance in the renal and segmental arteries. Blood velocity in 14 healthy adults (26 ± 4 yr; 7 women, 7 men) was measured in the renal and segmental arteries with Doppler ultrasound while subjects breathed room air (Air) and while they breathed a 3% CO₂, 21% O₂, 76% N₂ gas mixture for 5 min (CO₂). The end-tidal partial pressure of CO₂ ([Formula: see text]) was measured via capnography. Mean arterial pressure (MAP) was measured beat to beat via the Penaz method. Vascular resistance in the renal and segmental arteries was calculated as MAP divided by blood velocity. [Formula: see text] increased with CO₂ (Air: 45 ± 3, CO₂: 48 ± 3 mmHg, P < 0.01), but there were no changes in MAP (P = 0.77). CO₂ decreased blood velocity in the renal (Air: 35.2 ± 8.1, CO₂: 32.2 ± 7.3 cm/s, P < 0.01) and segmental (Air: 24.2 ± 5.1, CO₂: 21.8 ± 4.2 cm/s, P < 0.01) arteries and increased vascular resistance in the renal (Air: 2.7 ± 0.9, CO₂: 3.0 ± 0.9 mmHg·cm^-1·s, P < 0.01) and segmental (Air: 3.9 ± 1.0, CO₂: 4.4 ± 1.0 mmHg·cm^-1·s, P < 0.01) arteries. These data provide evidence that the kidneys are hemodynamically responsive to a mild and acute hypercapnic stimulus in healthy humans.

Lung-kidney interactions in critically ill patients: consensus report of the Acute Disease Quality Initiative (ADQI) 21 Workgroup

BACKGROUND

Multi-organ dysfunction in critical illness is common and frequently involves the lungs and kidneys, often requiring organ support such as invasive mechanical ventilation (IMV), renal replacement therapy (RRT) and/or extracorporeal membrane oxygenation (ECMO).

METHODS

A consensus conference on the spectrum of lung-kidney interactions in critical illness was held under the auspices of the Acute Disease Quality Initiative (ADQI) in Innsbruck, Austria, in June 2018. Through review and critical appraisal of the available evidence, the current state of research, and both clinical and research recommendations were described on the following topics: epidemiology, pathophysiology and strategies to mitigate pulmonary dysfunction among patients with acute kidney injury and/or kidney dysfunction among patients with acute respiratory failure/acute respiratory distress syndrome. Furthermore, emphasis was put on patients receiving organ support (RRT, IMV and/or ECMO) and its impact on lung and kidney function.

CONCLUSION

The ADQI 21 conference found significant knowledge gaps about organ crosstalk between lung and kidney and its relevance for critically ill patients. Lung protective ventilation, conservative fluid management and early recognition and treatment of pulmonary infections were the only clinical recommendations with higher quality of evidence. Recommendations for research were formulated, targeting lung-kidney interactions to improve care processes and outcomes in critical illness.

C-reactive protein as a biomarker of response to inhaled corticosteroids among patients with COPD

AIMS

C-reactive protein (CRP) is an important biomarker in systemic inflammation in COPD; reports have suggested inhaled corticosteroids (ICS) attenuate CRP levels. We evaluated the risk of moderate-to-severe exacerbations, severe exacerbations and all-cause mortality among patients with COPD currently exposed to Inhaled corticosteroids (ICS) stratified by CRP levels compared to never ICS users with low CRP levels.

METHODS

We included subjects age 40 or more who had a diagnosis of COPD from January 1, 2005 to January 31, 2014 from the UK Clinical Practice Research Datalink (CPRD). ICS exposure was determined time-dependently, as current, recent, past or never users. We evaluated the risk of moderate-to-severe exacerbations, severe exacerbations and all-cause mortality among ICS users stratified by CRP levels.

RESULTS

17,722 subjects diagnosed with COPD met the inclusion criteria. Among current or never ICS with elevated CRP levels we found, no significantly reduced risk of moderate-to-severe or severe exacerbations. For patients currently exposed ICS with CRP levels ≥8 mg/L there was no reduced risk of moderate-to-severe exacerbations (adjusted hazard ratio [adj. HR] 0.99; 95% confidence interval [CI] 0.76-1.31) or severe exacerbations (adj.HR 1.52; 95% CI 0.71-3.27). However, we found an increased risk of all-cause mortality among COPD patients with CRP levels ≥8 mg/L irrespective of ICS exposure.

CONCLUSION

We did not find a reduced risk of moderate and/or severe COPD exacerbations among COPD patients with varying CRP levels currently exposed to ICS. However, low-grade systemic inflammation was associated with all-cause mortality among COPD patients.

Assessing the accuracy of ICD-10 coding for measuring rates of and mortality from acute kidney injury and the impact of electronic alerts: an observational cohort study

Background

The application of a uniform definition for acute kidney injury (AKI) is vital to advance understanding and management of AKI. International Classification of Diseases (Tenth Revision) (ICD-10) coding is frequently used to define AKI, but its accuracy is unclear. The aim of this study was to determine whether ICD-10 coding is a reliable method of monitoring rates and outcomes of AKI in inpatients compared with biochemically defined AKI, and whether electronic alerts (e-alerts) for AKI affect ICD-10 AKI coding.

Methods

An observational cohort study of all 505 662 adult admissions to acute hospitals in two Scottish Health Boards [National Health Service (NHS) Tayside and NHS Fife] from January 2013 to April 2017 was performed. AKI e-alerts were implemented in NHS Tayside in April 2015. Sensitivity, specificity, positive and negative predictive values of ICD-10 coding for AKI compared with biochemically defined AKI using the Kidney Disease: Improving Global Outcomes definition and relative risk of 30-day mortality in people with ICD-10 and biochemically defined AKI before and after AKI e-alert implementation were performed.

Results

Sensitivity of ICD-10 coding for identifying biochemically defined AKI was very poor in both health boards for all AKI (Tayside 25.7% and Fife 35.8%) and for Stages 2 and 3 AKI (Tayside 43.8% and Fife 53.8%). Positive predictive value was poor both for all AKI (Tayside 76.1% and Fife 45.5%) and for Stages 2 and 3 AKI (Tayside 45.5% and Fife 36.8%). Measured mortality fell following implementation of AKI e-alerts in the ICD-10-coded population but not in the biochemically defined AKI population, reflecting an increase in the proportion of Stage 1 AKI in ICD-10-coded AKI. There was no evidence that the introduction of AKI e-alerts in Tayside improved ICD-10 coding of AKI.

Conclusion

ICD-10 coding should not be used for monitoring of rates and outcomes of AKI for either research or improvement programmes.

Building toolkits for COPD exacerbations: lessons from the past and present

In the nineteenth century, it was recognised that acute attacks of chronic bronchitis were harmful. 140 years later, it is clearer than ever that exacerbations of chronic obstructive pulmonary disease (ECOPD) are important events. They are associated with significant mortality, morbidity, a reduced quality of life and an increasing reliance on social care. ECOPD are common and are increasing in prevalence. Exacerbations beget exacerbations, with up to a quarter of in-patient episodes ending with readmission to hospital within 30 days. The healthcare costs are immense. Yet despite this, the tools available to diagnose and treat ECOPD are essentially unchanged, with the last new intervention (non-invasive ventilation) introduced over 25 years ago.An ECOPD is 'an acute worsening of respiratory symptoms that results in additional therapy'. This symptom and healthcare utility-based definition does not describe pathology and is unable to differentiate from other causes of an acute deterioration in breathlessness with or without a cough and sputum. There is limited understanding of the host immune response during an acute event and no reliable and readily available means to identify aetiology or direct treatment at the point of care (POC). Corticosteroids, short acting bronchodilators with or without antibiotics have been the mainstay of treatment for over 30 years. This is in stark contrast to many other acute presentations of chronic illness, where specific biomarkers and mechanistic understanding has revolutionised care pathways. So why has progress been so slow in ECOPD? This review examines the history of diagnosing and treating ECOPD. It suggests that to move forward, there needs to be an acceptance that not all exacerbations are alike (just as not all COPD is alike) and that clinical presentation alone cannot identify aetiology or stratify treatment.

Factors associated with a reduction in glomerular filtration rate in patients with chronic obstructive pulmonary disease

Aim. Analysis of factors associated with reduced glomerular filtration rate (GFR) in patients with chronic obstructive pulmonary disease (COPD). Materials and methods. The study included 198 patients with COPD 1-4 degrees of severity (GOLD 2014), who were on examination and treatment in Krasnodar Regional clinical hospital № 2. The control group consisted of 28 healthy volunteers, comparable in age and sex. In addition to clinical research, all patients, we calculated GFR according to the formula CKD-EPI based on cystatin C serum (GFRcys). The contribution of the factors in the risk of developing CKD was determined using multivariate linear regression analysis, as dependent variable used the value of GFRcys. Results and discussion. It was found that more than half (51.5%) of patients with COPD have a decrease in GFRcys

Blood eosinophilia, use of inhaled corticosteroids, and risk of COPD exacerbations and mortality

PURPOSE

It remains unclear whether eosinophilia is useful for in guiding inhaled corticosteroid (ICS) therapy in chronic obstructive pulmonary disease (COPD) patients. The goal of this study is to evaluate the risk of acute exacerbations, COPD-related hospitalisations/accident and emergency visits, and all-cause mortality with various levels of eosinophil counts among COPD patients using ICS.

METHODS

A cohort study was conducted using the UK Clinical Practice Research Datalink. Patients were aged 40+ and had COPD (n = 32 693). Current users of ICS were stratified by relative and absolute eosinophil counts to determine the risk of outcomes with blood eosiniphilia using Cox regression analysis.

RESULTS

Among COPD patients, current use of ICS was not associated with a reduced risk of acute COPD exacerbations, COPD-related hospitalisations/accident and emergency visits, and all-cause mortality. Stratification of ICS use by absolute or relative eosinophil counts did not result in significant differences in risk of COPD exacerbations or hospitalisations/accident and emergency visits. However, all-cause mortality was reduced by 12% to 24% among patients with eosinophilia.

CONCLUSIONS

COPD-related acute exacerbations or hospitalisations/accident and emergency visits were not reduced with eosinophilia among users of ICS with COPD. However, all-cause mortality was reduced by 12% to 24%. These findings are potentially important and require further evaluation in prospective studies.

Trends in moderate and severe exacerbations among COPD patients in the UK from 2005 to 2013

INTRODUCTION

Exacerbations of chronic obstructive pulmonary disease are characterised by increased symptoms such as dyspnoea, cough and sputum production and/or purulence, leading to greater risk of hospitalisation and mortality. Very few studies have measured long term trends in the incidence of exacerbations of chronic obstructive pulmonary disease. We therefore investigated the incidence of moderate and severe exacerbations in the UK general population.

METHODS

A population based-study including Clinical Practice Research Datalink (CPRD) patients ≥ 40 years of age with a current diagnosis of COPD within the United Kingdom from 2004 to 2013 was conducted. Individuals with a history of asthma were excluded from main analyses. We calculated the incidence rates for any, moderate, and severe exacerbations. Patients contributed time at risk from January 1st up to the date of the first outcome within each year. The incidence rate for any, moderate and severe exacerbations for COPD in each calendar year was calculated as follows: the sum of any or moderate or severe exacerbations for COPD in that year divided by the total duration of follow-up in the same calendar year from 2005 through to 2013. We then analysed these rates by gender and age categories (40-59 years, 60-79 years and ≥80 years).

RESULTS

Among 213,561 with incident COPD diagnosis, 86,300 patients were included in the study. From 2005 to 2013, the incidence rate of any exacerbations increased from 89 to 98 per 1000 person years (PYs) (p = 0.005). Women had significantly higher incidence rates of any exacerbation for each calendar year when compared to men (p < 0.0001). The incidence rate of any and moderate exacerbations increased with age from 2005 to 2007. For severe exacerbations incidence decreased from 2005 to 2007 before increasing from 2008 until the end of follow-up (43 per 1000 PYs (95% confidence interval, 42-45/1000PYs) in 2013). Incidence rates of severe exacerbations were similar by gender and patients aged 80 + years had a higher incidence rate of severe exacerbation from 2005 to 2008 after which their incident rate dropped in subsequent years.

CONCLUSION

This is the first study that reports the long-term changes in the incidence rates of moderate and severe exacerbations within the UK general practice. Women showed a substantially higher risk of any COPD exacerbations, and their risk is increasing. The incidence rates of any exacerbations increased during the study period, while severe exacerbations were variable. Furthermore, incidence rates varied substantially by age group.

Community-acquired versus hospital-acquired acute kidney injury in patients with acute exacerbation of COPD requiring hospitalization in China

Purpose

Previous studies have described the incidence, risk factors, and outcomes for patients with acute exacerbations of COPD (AECOPD) developing acute kidney injury (AKI). However, little is known about the differences between community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI) in patients with AECOPD. Thus, in this study, we compared prevalence, risk factors, and outcomes for these patients with CA-AKI and HA-AKI.

Patients and methods

This study was conducted from January 2014 to January 2017, and data from adult inpatients with AECOPD were analyzed retrospectively. A total of 1,768 patients were included, 280 patients were identified with CA-AKI and 97 patients were with HA-AKI.

Results

Prevalence of CA-AKI was 15.8% and that of HA-AKI was 5.5%, giving an overall AKI prevalence of 21.3%. Patients with CA-AKI had a higher prevalence of chronic kidney disease (CKD) and lower prevalence of chronic cor pulmonale than patients with HA-AKI. Risk factors for developing HA-AKI and CA-AKI were similar, such as being elderly, requirement for mechanical ventilation, and a history of coronary artery disease and CKD. Patients with HA-AKI were more likely to have stage 3 AKI and worse short-term outcomes. In comparison with patients with CA-AKI, those with HA-AKI were more likely to require non-invasive mechanical ventilation (31.3% versus 16.8%; P = 0.003) and had a longer duration of mechanical ventilation (11 days versus 8 days; P = 0.020), longer hospitalization (14 days versus 12 days; P = 0.038), and higher inpatient mortality (32.0% versus 13.2%; P < 0.001). Patients with HA-AKI had worse (multivariate-adjusted) inpatient survival than those with CA-AKI (hazard ratio, 1.7 [95% confidence interval, 1.03-2.81; P = 0.038] for the HA-AKI group).

Conclusion

AKI was common in patients with AECOPD requiring hospitalization. CA-AKI was more common than HA-AKI but otherwise demonstrated similar demographics and risk factors. Nevertheless, patients with HA-AKI had worse short-term outcomes.

Age modifies the risk factor profiles for acute kidney injury among recently diagnosed type 2 diabetic patients: a population-based study

The incidence of acute kidney injury (AKI) rises with age and is associated with multiple risk factors. Here, we compared the risk factors for AKI between younger and older incident diabetic patients to examine the trends in risk alteration for individual factors across different age groups. Between 2007 and 2013, we selected all incident type 2 diabetic adults from the Taiwan National Health Insurance registry, stratified based on age: young (< 65 years), old (≥ 65 but < 75 years), and older-old (≥ 75 years). All factors with potential renal influence (e.g., comorbidities, medications, and diagnostics/procedures) were recorded during the study period, with a nested case-controlled approach utilized to identify independent risk factors for AKI in each age group. Totally, 930,709 type 2 diabetic patients were categorized as young (68.7%), old (17.7%), or older-old (13.6%). Older-old patients showed a significantly higher incidence of AKI than the old and the young groups. Cardiovascular morbidities (hypertension, atrial fibrillation, acute coronary syndrome, and cerebrovascular disease) were shown to increase the risk of AKI, although the risk declined with increasing age. Chronic obstructive pulmonary disease and receiving cardiac catheterization elevated the risk of AKI preferentially in the older-old/old and older-old group, respectively, while the administration of angiotensin-converting enzyme/α-blocker and angiotensin receptor blocker/calcium channel blocker reduced the risk of AKI preferentially in the older-old and older-old/old group, respectively. In conclusion, our findings highlight the importance of devising age-specific risk factor panels for AKI in patients with recently diagnosed type 2 diabetes.

Lung Function and Incident Kidney Disease: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Reduced lung function is associated with clinical outcomes such as cardiovascular disease. However, little is known about its association with incident end-stage renal disease (ESRD) and chronic kidney disease (CKD).

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

14,946 participants aged 45 to 64 years at baseline (1987-1989) in the Atherosclerosis Risk in Communities (ARIC) Study (45.0% men and 25.2% black), with follow-up through 2012.

PREDICTORS

Race- and sex-specific quartiles of percent-predicted forced vital capacity (FVC) and the proportion of forced expiratory volume in 1 second of expiration to FVC (FEV1/FVC) at baseline determined with spirometry.

OUTCOMES

Incident ESRD (defined here as renal replacement therapy or death due to CKD) as the primary outcome and incident CKD (defined here as ESRD, ≥25% decline in estimated glomerular filtration rate to a level <60mL/min/1.73m2, or CKD-related hospitalizations/deaths) as the secondary outcome.

RESULTS

During a median follow-up of 23.6 years, 526 (3.5%) participants developed ESRD. After adjusting for potential confounders, the cause-specific HR of incident ESRD for the lowest (vs highest) quartile was 1.72 (95% CI, 1.31-2.26) for percent-predicted FVC and 1.33 (95% CI, 1.03-1.73) for FEV1/FVC. Compared to a high-normal lung function pattern, a mixed pattern (ie, percent-predicted FVC<80% and FEV1/FVC<70%; 3.4% of participants) demonstrated the highest adjusted cause-specific HR of ESRD at 2.28 (95% CI, 1.50-3.45), followed by the restrictive pattern (ie, percent-predicted FVC<80% and FEV1/FVC≥70%; 4.8% of participants) at 2.03 (95% CI, 1.47-2.81), obstructive pattern (ie, percent-predicted FVC≥80% and FEV1/FVC<70%; 18.9% of participants) at 1.47 (95% CI, 1.09-1.99), and low-normal pattern (ie, percent-predicted FVC 80%-<100% and FEV1/FVC≥70%, or percent-predicted FVC≥80% and FEV1/FVC 70%-<75%; 44.3% of participants) at 1.21 (95% CI, 0.94-1.55). Similar associations were seen with incident CKD.

LIMITATIONS

Limited number of participants with moderate/severe lung dysfunction and spirometry only at baseline.

CONCLUSIONS

Reduced lung function, particularly lower percent-predicted FVC, is independently associated with CKD progression. Our findings suggest a potential pathophysiologic contribution of reduced lung function to the development of CKD and a need for monitoring kidney function in persons with reduced lung function.

Effect of continuous dialysis on blood ph in acidemic hypercapnic animals with severe acute kidney injury: a randomized experimental study comparing high vs. low bicarbonate affluent

Background

Controlling blood pH during acute ventilatory failure and hypercapnia in individuals suffering from severe acute kidney injury (AKI) and undergoing continuous renal replacement therapy (CRRT) is of paramount importance in critical care settings. In this situation, the optimal concentration of sodium bicarbonate in the dialysate is still an unsolved question in critical care since high concentrations may worsen carbon dioxide levels and low concentrations may not be as effective in controlling pH.

Methods

We performed a randomized, non-blinded, experimental study. AKI was induced in 12 female pigs via renal hilum ligation and hypoventilation by reducing the tidal volume during mechanical ventilation with the goal of achieving a pH between 7.10–7.15. After achieving the target pH, animals were randomized to undergo isovolemic hemodialysis with one of two bicarbonate concentrations in the dialysate (40 mEq/L [group 40] vs. 20 mEq/L [group 20]).

Results

Hemodynamic, respiratory, and laboratory data were collected. The median pH value at CRRT initiation was 7.14 [7.12, 7.15] in group 20 and 7.13 [7.09, 7.14] in group 40 (P = ns). The median baseline PaCO₂ was 74 [72, 81] mmHg in group 20 vs. 79 [63, 85] mmHg in group 40 (P = ns). After 3 h of CRRT, the pH value was 7.05 [6.95, 7.09] in group 20 and 7.12 [7.1, 7.14] in group 40 (P < 0.05), with corresponding values of PaCO₂ of 85 [79, 88] mmHg vs. 81 [63, 100] mmHg (P = ns). The difference in pH after 3 h was due to a metabolic component [standard base excess −10.4 [−12.5, −9.5] mEq/L in group 20 vs. –7.6 [−9.2, −5.1] mEq/L in group 40) (P < 0.05)]. Despite the increased infusion of bicarbonate in group 40, the blood CO₂ content did not change during the experiment. The 12-h survival rate was higher in group 40 (67% vs. 0, P = 0.032).

Conclusions

A higher bicarbonate concentration in the dialysate of animals undergoing hypercapnic respiratory failure was associated with improved blood pH control without increasing the PaCO₂ levels.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0141-6) contains supplementary material, which is available to authorized users.

Lung and kidney: a dangerous liaison? A population-based cohort study in COPD patients in Italy

Background

COPD is among the major causes of death, and it is associated with several comorbid conditions. Chronic kidney disease (CKD) is frequently diagnosed in older people living in Western societies and could impact COPD patients’ mortality. We evaluated the relationship between burden of comorbidities, CKD, and mortality in a population-based cohort of patients discharged with a diagnosis of COPD.

Methods

A longitudinal cohort study was conducted evaluating 27,272 COPD patients. Recruitment of COPD subjects and identification of CKD and other comorbidities summarized by the Charlson comorbidity index (CCI) were based on claims data coded according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). Severity of COPD was classified by hospital diagnosis or exemption from medical charges due to respiratory failure or previous hospitalizations for COPD. The impact of comorbidities on survival was assessed by Cox regression.

Results

Less than 40% of patients were still alive at the end of a median follow-up of 37 months (17 months for patients who died and 56 months for those alive at the end of follow-up). After adjustment for age, gender, and severity score of COPD, CKD (hazard ratio =1.36, 95% confidence interval 1.30–1.42) independently from comorbidities summarized by the CCI was a significant risk factor for mortality.

Conclusion

In spite of limitations due to the use of claims data, long-term survival of COPD patients was heavily affected by the presence of CKD and other comorbidities.

Impact of renal dysfunction on in-hospital mortality of patients with severe chronic obstructive pulmonary disease: a single-center Italian study

BACKGROUND

We conducted a study, based on discharge hospital sheets [International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM)], in order to evaluate the relationship between chronic kidney disease (CKD), acute kidney injury (AKI), multi-morbidity, and in-hospital mortality (IHM).

METHODS

This study included all hospital admissions for chronic obstructive pulmonary disease (COPD) exacerbations between January 1, 2000, and December 31, 2013, recorded in the database of the University Hospital St. Anna of Ferrara. Age, sex, and diagnosis of CKD and AKI were collected, and Charlson comorbidity index (CCI) was calculated by ICD-9-CM codes. IHM was our main outcome.

RESULTS

We analyzed 7073 subjects with COPD exacerbation; they were more frequently male (56.9 vs 43.1 %), and mean age was 76.7 ± 9.8 years. Diagnosis of CKD was present in 771 patients (10.9 %), while AKI was diagnosed in 354 cases (5 %). A total of 554 patients (7.8 %) died during hospitalization, and LOS was 10.3 ± 11.2 days (median 8 days); the CCI corrected for CKD was 2.30 ± 1.65. Univariate analysis showed that IHM group had higher age (81.2 ± 7.9 vs 76.3 ± 9.9 years, p < 0.001), CCI (2.61 ± 2.21 vs 2.28 ± 1.62, p = 0.001), and LOS (11.1 ± 15.1 vs 10.3 ± 10.8 days, p = 0.001) and developed AKI more frequently (16.6 vs 4 %, p < 0.001) than survivors. Multivariate logistic regression analysis showed an independent association of IHM with age (OR 1.063; 95 % CI 1.050-1.075, p < 0.001), male sex (OR 1.229; 95 % CI 1.016-1.486, p = 0.033), logCCI (OR 2.051; 95 % CI 1.419-2.964, p < 0.001), and AKI (OR 3.849; 95 % CI 2.874-5.155, p < 0.001).

CONCLUSIONS

Acute kidney injury (AKI) represents a very important predictive factor of IHM in male older adult with multi-morbidity admitted because of COPD exacerbations.

Kidney-lung connections in acute and chronic diseases: current perspectives

Lung and kidney functions are intimately related in both health and disease. The regulation of acid-base equilibrium, modification of partial pressure of carbon dioxide and bicarbonate concentration, and the control of blood pressure and fluid homeostasis all closely depend on renal and pulmonary activities. These interactions begin in fetal age and are often responsible for the genesis and progression of diseases. In gestational age, urine is a fundamental component of the amniotic fluid, acting on pulmonary maturation and growth. Moreover, in the first trimester of pregnancy, kidney is the main source of proline, contributing to collagen synthesis and lung parenchyma maturation. Pathologically speaking, the kidneys could become damaged by mediators of inflammation or immuno-mediated factors related to a primary lung pathology or, on the contrary, it could be the renal disease that determines a consecutive pulmonary damage. Furthermore, non immunological mechanisms are frequently involved in renal and pulmonary diseases, as observed in chronic pathologies such as sleep apnea syndrome, pulmonary hypertension, progressive renal disease and hemodialysis. Kidney damage has also been related to mechanical ventilation. The aim of this review is to describe pulmonary-renal interactions and their related pathologies, underscoring the need for a close collaboration between intensivists, pneumologists and nephrologists.