Objectives: We evaluated the frequency and cause of acute respiratory failure in renal transplant recipients.
Materials and Methods: Our single-center retrospective observational study included consecutive renal transplant recipients who were admitted to an intensive care unit for acute respiratory failure between 2011 and 2017. Acute respiratory failure was defined as oxygen saturation < 92% or partial pressure of oxygen in arterial blood < 60 mm Hg on room air and/or requirement of noninvasive or invasive mechanical ventilation.
Results: Of 187 renal transplant recipients, 35 (18.71%) required intensive care unit admission; 11 of these patients (31.4%) were admitted to the intensive care unit with acute respiratory failure. Six of these patients (54.5%) had pneumonia and had shown infiltrates on chest radiography, which were shown in a minimum of 3 zones of the lung (2 with Klebsiella pneumonia, 1 with Acinetobacter species, 1 with Proteus mirabilis, 2 with no microorganisms). The other reasons for acute respiratory failure were cardiogenic pulmonary edema (2 patients), acute respiratory distress syndrome (2 patients, due to acute pancreatitis and acute cerebrovascular thromboembolism), and exacerbation of chronic obstructive pulmonary disease (1 patient). Six patients (54.5%) needed invasive mechanical ventilation because of pneumonia (3 patients), cardiogenic pulmonary edema (2 patients), and cerebrovascular thromboembolism (1 patient). Hemodialysis was administered in 5 patients (45%). Six of 11 patients died due to pneumonia (3 patients), cardiogenic pulmonary edema (2 patients), and cerebrovascular thromboembolism (1 patient). Among the 5 survivors, 3 (60%) had recovered previous graft function.
Conclusions: Acute respiratory failure is associated with high mortality and morbidity in renal transplant recipients. Main causes of acute respiratory failure were bacterial pneumonia and cardiogenic pulmonary edema in our study population. Extended chemoprophylaxis for bacterial and fungal infection and early intensive care unit admission of patients with acute respiratory failure may improve outcomes.
Key words : Bacterial infection, Kidney transplantation, Pulmonary disease
Renal transplantation is the best treatment option for end-stage renal disease. It provides a better quality of life than hemodialysis, increases survival, and is more cost-effective. Renal transplant has been widely used all over the world due to development of immunosuppressive treatments and surgical techniques. With its common use, elderly renal transplant recipients with associated comorbidities and intense immunosuppressive treatments bring various complications.1 In addition, end-stage renal disease increases the risk of immunosuppression, volume overload, and cardiovascular disease. It has also been shown that renal transplant increases pulmonary complications2; correspondingly, it is possible that acute respiratory failure (ARF) can occur. Noninfectious causes in the postoperative early period and infectious causes in the late period are the main reasons for ARF. Respiratory failure in the postoperative period has a high risk of mortality and morbidity. It extends the length of stay in the hospital and in the intensive care unit (ICU).1,3
In our study, we aimed to evaluate the frequency of ARF, as well as reasons and mortality rates, in renal transplant recipients with ARF.
Materials and Methods
This study included patients who were admitted to the ICU due to ARF and who had previous renal transplant procedures between August 2011 and December 2017 at Baskent University Adana Hospital. Patient medical records were examined retrospectively. Acute respiratory failure was defined as the decrease of oxygen saturation (< 92%) in room air with severe respiratory distress or hypoxemia (partial oxygen pressure < 60 mm Hg) and/or requirement of invasive/noninvasive mechanical ventilation. Pneumonia was defined as acute onset of respiratory symptoms with new infiltration on chest radiography. Chronic obstructive pulmonary disease exacerbation was defined as an acute worsening of respiratory symptoms requiring a change in treatment. Acute cardiogenic pulmonary edema was defined as sudden onset of dyspnea, bilateral rales, and typical findings of congestion on chest radiography without a history suggesting pulmonary aspiration or evidence of pneumonia. The definition of acute respiratory distress syndrome (ARDS) was based on the American-European Consensus Conference Committee on ARDS.4
Demographic characteristics, comorbidities, and invasive and noninvasive procedures administered to patients were recorded. Pathologies causing ARF were examined. Patients under 18 years of age were not included in the study.
Variables are presented as mean and standard deviation or median (range, interquartile range) for continuous data and as proportion for categorical data. Shapiro-Wilks test was used to identify whether continuous variables were normally distributed.
Among the 187 renal transplant recipients, 35 (18.71%) were admitted to the ICU. Eleven of these patients (31.4%) were admitted to the ICU with ARF. Baseline demographics, clinical results, and laboratory data are summarized in Table 1.
Six of the 11 patients (54%) with ARF had pneumonia. When chest radiography scans were evaluated, areas of pneumonic infiltration were observed in at least 3 lung zones. Respiratory secretion samples of 1 patient who was diagnosed with pneumonia were taken by fiberoptic bronchoscopy, and 3 samples were taken by tracheal aspirate. On sputum, deep tracheal aspirate, and bronchial lavage samples, Klebsiella pneumonia (n = 2), Acinetobacter species (n = 1), Proteus mirabilis (n = 1), or no microorganisms (n = 2) were detected. Besides pneumonia, other causes of ARF were cardiogenic pulmonary edema (n = 2), ARDS (n = 2; due to acute pancreatitis and acute cerebrovascular thromboembolism), and exacerbation of chronic obstructive pulmonary disease (n = 1).
Five patients (45%) with ARF needed hemodialysis while in the ICU. Graft function in 3 of these 5 patients returned to normal laboratory values and discharge from the ICU (18%). Six of 11 patients (54%) died. Causes of death were pneumonia (n = 3), cardiogenic pulmonary edema (n = 2), and cerebrovascular thromboembolism (n = 1).
When we retrospectively examined the adult patients who had renal transplant procedures in our hospital, we found that the primary cause of ARF was pneumonia. Nosocomial bacterial infections, including gram-negative pathogens, were frequent. In terms of the need for invasive mechanical ventilation, most were because of pneumonia. Mortality was also high in our renal transplant recipients with ARF. The primary causes of death were shown to be pneumonia and cardiogenic pulmonary edema.
Acute respiratory failure is not commonly seen in renal transplant recipients but has a high mortality rate. In a study by Ulas and associates, 10.7% of renal transplant recipients were admitted to the ICU, with median time of 10 months after transplant.5 The incidence of ARF for these patients was 47%, and the mortality rate was 23%.5 In a series of 6819 patients who were renal transplant recipients, 6.6% were admitted to the ICU, with 47.8% admitted to the ICU due to ARF; median time to admission was 17 months after transplant.6 Our results seem to be consistent with this study.
Acute respiratory failure can be classified as early (< 100 days) or late (> 100 days) posttransplant. Infections causing ARF are more commonly seen in the late period. Infections are also the primary reason for those admitted to ICUs and are related to death. Candan and associates7 reported that respiratory-related infections were the primary reason for admission of patients to ICUs in the late postoperative period due to infection. In a 4-year follow-up in renal transplant recipients, rate of pneumonia incidence was 61.5%, with pneumonia being the primary infection requiring ICU hospitalization.7 In our study, the primary cause of ARF was pneumonia (54%), and the detectable pathogens were mostly gram-negative bacteria. Klebsiella pneumoniae (33.33%) and Acinetobacter baumannii (33.33%) were both isolated.
Canet and associates6 found that 25% of patients admitted to the ICU with ARF should continue hemodialysis treatment.6 In our study, we observed that 18.18% of renal transplant recipients admitted to the ICU with ARF required return to renal replacement treatment.
A limitation of our study was the small number of patients. Other limitations were the study’s retrospective design and the different times that passed after transplant for each patient.
Acute respiratory failure is not a common health problem in renal transplant recipients but has a high rate of mortality and morbidity. Bacterial pneumonia and cardiogenic pulmonary edema were the primary causes of ARF in our study. Early diagnosis and treatment of bacterial pneumonia can reduce mortality. Mortality and morbidity of pneumonia were higher in renal transplant recipients and in those with other immunosuppressive conditions. For this reason, suitable chemoprophylaxis in this group of patients may decrease ARF and admissions to the ICU.
Volume : 17
Issue : 1
Pages : 172 - 174
DOI : 10.6002/ect.MESOT2018.P49
From the 1Department of Pulmonary Medicine, Baskent University, Adana, Turkey;
the 2Department of Pulmonary Medicine, Baskent University, Ankara, Turkey; the
3Department of General Surgery, Baskent University, Adana, Turkey; and the
4Department of General Surgery, Baskent University, Ankara, Turkey
Acknowledgements: The authors have no conflicts of interest and have no financial relationships relevant to this article to disclose.
Corresponding author: H. Eylül Bozkurt Yılmaz, Dadaloğlu Mahallesi, 2591 sokak. No: 4/A 01250 Yüreğir, Baskent University, Department of Pulmonary Medicine Adana Teaching and Research Center, Adana, Turkey
Phone: +90 322 327 27 27 ext: 41097
Table 1. Baseline Clinic Characteristics of the Study Population (N = 11)