[Acute severe respiratory distress in chronic haemodialytic patients affected by SARS-CoV-2 pneumonia: prevalence and associated factors. A single-centre experience from Cardarelli Hospital in Naples (Italy)].

Background: SARS­CoV­2-induced severe acute respiratory syndrome is associated with high mortality in the general population; however, the data on chronic haemodialysis (HD) patients are currently scarce. Methods: We performed a retrospective analysis to evaluate the onset of acute respiratory distress syndrome (ARDS) in patients with SARS­CoV­2-induced interstitial pneumonia diagnosed by PCR test and detected by high resolution computed tomography (HRCT). For each patient, we calculated a CT score between 0 and 24, based on the severity of pneumonia. The primary outcome was the onset of ARDS, detected by P/F ratio >200. We included 57/90 HD patients (age: 66.5 ±13.4 years, 61.4 % males, 42.1% diabetics, 52.6% CV disease) treated at the Cardarelli Hospital in Naples (Italy) from 1st September 2020 to 31st March 2021. All patients were treated with intermittent HD. Results: Patients who experienced ARDS had a more severe pneumonia (CT score: 15 [C.I.95%:10-21] in ARDS patients vs 7 [C.I.95%: 1-16] in no ARDS; P=0.015). Logistic regression showed that the CT score was the main factor associated with the onset of ARDS (1.12; 95% c.i.: 1.00-1.25), independently from age, gender, diabetes, chronic obstructive pulmonary disease, and prior CV disease. Thirty-day mortality was much greater in ARDS patients (83,3%) than in no-ARDS (19.3%). Conclusions: This retrospective analysis highlights that HD patients affected by SARS-CoV-2 pneumonia show an increased risk of developing ARDS, dependent on the severity of CT at presentation. This underlines once again the need for prevention strategies, in primis the vaccination campaign, for these frail patients.

Reproducibility of regional pulse-wave velocity in uremic subjects.

Despite the clinical importance of pulse-wave velocity (PWV), there are no standards for accurate carotid-radial pulse-wave measurement in uremic patients with respect to carotid-femoral measurement. We assessed the reproducibility of PWV values using the carotid-radial PWV measurement. We have measured the carotid-femoral PWV and carotid-radial PWV with an automated system (Pulse Pen, DiaTecne) using 2 different blind operators in 105 hemodialysis (HD) patients. The carotid-femoral waveforms were acquired by the first blind operator simultaneously with 2 pressure-sensitive transducers and the transit time of the pulse was calculated using the system software. Similarly, the second blind operator acquired the carotid-radial waveforms. The two operators performed 2 consecutive measurements from the same subject, in a random order. In fact, after the first operator had completed 2 consecutive measurements from 1 subject, all of the sensors were detached, and the second operator attached sensors again to the same subject. The measurements were performed during interval of a midweek dialysis-free day. To evaluate the reproducibility of the system, both within-observer and between-observer analyses were performed. We studied 105 dialysis patients (HD) and 20 controls. All HD patients had three dialysis sessions lasting at least 4 h/wk. A total of 28 patients (26.7%) had diabetic nephropathy. The mean age of HD was 64.6 ± 16.1 years, the body weight was 71.1 ± 15.1 kg, and the height was 164.6 ± 6.1 cm. All population studied is referral at a tertiary care from at least 6 months (mean 11.1 ± 2.1 months). A total of 45% of patients are smokers or ex-smokers. The PWV of carotid-femoral is 8.58 ± 3.99 and the PWV of carotid-radial is 8.70 ± 4.01 m/sec, respectively, by the first and the second operator; the difference of PWV (femoral-radial measure) is -0.037 ± 0.99 m/sec. The linear correlation of carotid-femoral vs. carotid-radial PWV measurements is the highest (R(2) =0.90). The results regarding reproducibility, including mean differences and standard deviations, standard errors, and correlation coefficients were analyzed for each regional PWV value for the between-observer and within-observer studies. All of the measurements showed significant correlation coefficients, ranging from 0.94 to 0.98. The reproducibility of regional PWV values for 2 consecutive measurements from the same subject was also analyzed using Bland-Altman plots, with the reproducibility expressed as the mean difference and 2 standard deviations between the measurements obtained by the 2 operators during carotid-femoral and carotid-radial measurements. Carotid-radial PWV measurement provides an accurate analysis with a high reproducibility with respect to carotid-femoral PWV measurement, and it can be used for arterial stiffness analysis in hemodialysis patients.