Errors in the arterial blood pressure measurement

ntroduction The artefacts affecting arterial wave morphology may compromise recorded values of arterial blood pressure (ABP) and can lead to therapeutic errors. The aim of this study is to evaluate the errors between invasive and noninvasive arterial pressure values, the incidence of artefacts due to an inadequate dynamic response of the transducer-tubing system, and their detection by the ICU staff. Methods Seventy-five consecutive patients (50 male, mean age 55 ± 18) admitted to the ICU for heterogeneous pathologies were enrolled. Inclusion criteria were: the presence of an intra-arterial catheter (IAC) for invasive blood pressure monitoring, and age >18 years. Pregnancy was excluded. At admission and every time the IAC was replaced we acquired invasive systolic, diastolic, and medium arterial pressure values (I-SP, I-DP, I-MP) during hemodynamic stability (variations of mean arterial pressure <10%); at the same time, noninvasive systolic and diastolic arterial pressure values (Ni-SP, Ni-DP) were measured with a sphygmomanometer at the same arm of the IAC. Noninvasive medium arterial pressure (Ni-MP) was calculated as follows: (SP + 2DP) / 3. At every time of the study, before ABP value acquisition, medical and nursing staff answered a questionnaire on the reliability of the arterial waveform. The staff could perform the fast flush test if considered appropriate. However, the fast flush test was executed by the main investigator at the end of questionnaire in all patients. Bland–Altman analysis was performed. Results We compared 130 pairs of Ni-SP, Ni-DP and Ni-MP and I-SP, I-DP and I-MP. The mean bias between Ni-SP and I-SP was –11 mmHg (limit of agreement (LoA) –43.6 to 21.4 mmHg). The mean bias between Ni-DP and I-DP and between Ni-MP and I-MP was 6.1 mmHg (LoA –15.5 to 27.7 mmHg) and 0.37 mmHg (LoA –21.0 to 21.7 mmHg), respectively. We performed the fast flush test 130 times; an inadequate dynamic response of the transducer-tubing system was observed 55 times: in 45 cases the arterial signal was underdumped and in 10 cases was overdumped. The arterial dumping was correctly detected by the medical staff in 95% of cases, by nursing staff and postgraduates in 35% of cases. Conclusion The bias between invasive and noninvasive ABP measure can be relevant and mislead in the therapeutic management. These errors can be avoided by identifying the artefacts that affect arterial signal and so the ICU staff must pay attention to the recognition of arterial dumping in critically ill patients

A proof-of-concept study on the genomic evolution of Sars-Cov-2 in molnupiravir-treated, paxlovid-treated and drug-naïve patients

Little is known about SARS-CoV-2 evolution under Molnupiravir and Paxlovid, the only antivirals approved for COVID-19 treatment. By investigating SARS-CoV-2 variability in 8 Molnupiravir-treated, 7 Paxlovid-treated and 5 drug-naïve individuals at 4 time-points (Days 0-2-5-7), a higher genetic distance is found under Molnupiravir pressure compared to Paxlovid and no-drug pressure (nucleotide-substitutions/site mean±Standard error: 18.7 × 10−4 ± 2.1 × 10−4 vs. 3.3 × 10−4 ± 0.8 × 10−4 vs. 3.1 × 10−4 ± 0.8 × 10−4, P = 0.0003), peaking between Day 2 and 5. Molnupiravir drives the emergence of more G-A and C-T transitions than other mutations (P = 0.031). SARS-CoV-2 selective evolution under Molnupiravir pressure does not differ from that under Paxlovid or no-drug pressure, except for orf8 (dN &gt; dS, P = 0.001); few amino acid mutations are enriched at specific sites. No RNA-dependent RNA polymerase (RdRp) or main proteases (Mpro) mutations conferring resistance to Molnupiravir or Paxlovid are found. This proof-of-concept study defines the SARS-CoV-2 within-host evolution during antiviral treatment, confirming higher in vivo variability induced by Molnupiravir compared to Paxlovid and drug-naive, albeit not resulting in apparent mutation selection

Expansion of plasmablasts and loss of memory B cells in peripheral blood from COVID-19 patients with pneumonia

Studies on the interactions between SARS-CoV-2 and humoral immunity are fundamental to elaborate effective therapies including vaccines. We used polychromatic flow cytometry, coupled with unsupervised data analysis and principal component analysis (PCA), to interrogate B cells in untreated patients with COVID-19 pneumonia. COVID-19 patients displayed normal plasma levels of the main immunoglobulin classes, of antibodies against common antigens or against antigens present in common vaccines. However, we found a decreased number of total and na\uefve B cells, along with decreased percentages and numbers of memory switched and unswitched B cells. On the contrary, IgM+ and IgM 12 plasmablasts were significantly increased. In vitro cell activation revealed that B lymphocytes showed a normal proliferation index and number of dividing cells per cycle. PCA indicated that B-cell number, naive and memory B cells but not plasmablasts clustered with patients who were discharged, while plasma IgM level, C-reactive protein, D-dimer, and SOFA score with those who died. In patients with pneumonia, the derangement of the B-cell compartment could be one of the causes of the immunological failure to control SARS-Cov2, have a relevant influence on several pathways, organs and systems, and must be considered to develop vaccine strategies

Machine learning in predicting respiratory failure in patients with COVID-19 pneumonia - challenges, strengths, and opportunities in a global health emergency.

Aims- The aim of this study was to estimate a 48 hour prediction of moderate to severe respiratory failure, requiring mechanical ventilation, in hospitalized patients with COVID-19 pneumonia. Methods- This was an observational study that comprised consecutive patients with COVID-19 pneumonia admitted to hospital from 21 February to 6 April 2020. The patients\u2019 medical history, demographic, epidemiologic and clinical data were collected in an electronic patient chart. The dataset was used to train predictive models using an established machine learning framework leveraging a hybrid approach where clinical expertise is applied alongside a data-driven analysis. The study outcome was the onset of moderate to severe respiratory failure defined as PaO 2 /FiO 2 ratio &lt;150 mmHg in at least one of two consecutive arterial blood gas analyses in the following 48 hours. Shapley Additive exPlanations values were used to quantify the positive or negative impact of each variable included in each model on the predicted outcome. Results- A total of 198 patients contributed to generate 1068 usable observations which allowed to build 3 predictive models based respectively on 31-variables signs and symptoms, 39-variables laboratory biomarkers and 91-variables as a composition of the two. A fourth \u201cboosted mixed model\u201d included 20 variables was selected from the model 3, achieved the best predictive performance (AUC=0.84) without worsening the FN rate. Its clinical performance was applied in a narrative case report as an example. Conclusion- This study developed a machine model with 84% prediction accuracy, which is able to assist clinicians in decision making process and contribute to develop new analytics to improve care at high technology readiness levels

Reliability of pulse contour method-based hemodynamic measurements assessed by different operators.

INTRODUCTION. Pulse Contour Methods (PCMs) provide stroke volume (SV) and cardiac output (CO) from the analysis of the arterial waveform. Artifacts affecting arterial wave morphology may reduce the reliability of PCMs in estimating such haemodynamic variables. The new operator who is facing a PCM for the first time should need a training period to gain ability in recognizing artifacts and avoiding mistakes in CO assessment. OBJECTIVES. The aim of this study is to evaluate the potential bias rising when com- paring CO values obtained by transthoracic echocardiography (TTE-CO) and Most-Care (MC-CO) system recorded by trained (T) and not-trained operators (NT). METHODS. 23 consecutive patients (10 male, mean age 60 ± 15) admitted to general ICU for heterogeneous pathologies were enrolled. Inclusion criteria were: the presence of a radial artery catheter for invasive blood pressure monitoring, need for a transthoracic echocardi- ography evaluation, age [18 years old. Exclusion criteria were: cardiac arrhythmias, aortic valve pathologies, ascending aortic pathologies, pregnancy, arteriovenous fistulas, and significant artery obstruction. For each patient, during haemodynamic stability (i.e., mean arterial pressure changes\10 %), CO was obtained with Most-Care (Vytech Health, Padua, Italy) by T (i.e., who has been using Most-Care for at least 6 months) and NT operator (who had only read the user manual of MostCare). TTE-CO was performed with MyLabTM 70 Xvision (Esaote, Italy) by the same operator during CO measurements obtained by T and NT (T-CO, NT-CO). TTE-CO was calculated as the product of heart rate by SV averaged over five consecutive measurements obtained during both NT-CO and T-CO Most-Care estimations. Bland–Altman analysis was used. RESULTS. 46 paired CO values were obtained. TTE-CO values ranged from 3.0 to 8.9 l/ min, T-CO ranged from 3.2 to 9.0 l/min, and NT-CO from 4.5 to 16.0 l/min. The mean bias between T-CO and TTE-CO was 0.04 l/min (limits of agreement, LoA -0.5 to 0.6 l/min, percentage error, PE = 11 %), and between NT-CO and TTE-CO -2.8 l/min (LoA -9.8 to 4.5 l/min, PE [ 30 %). The fast flush test, to improve the quality of the arterial pressure waveform, was performed in 100 % of cases by T and in 48 % of cases by NT. Resonance over-shoot eliminator (R.O.S.E., Becton–Dickinson, Becton Drive, NJ) was used in 32 % of cases by T and in 9 % of cases by NT. CONCLUSIONS. The comparison between T-CO and NT-CO showed that bias and per- centage of errors were very relevant for NT. A period of training is needed for the new user to assess correctly CO values with such PCM. This would avoid misinterpretation of arterial pressure waveform-derived variables and could help the clinical staff to get reliable hemodynamic data for daily clinical practice

Positive end expiratory pressure-PEEP can affects the 4-chamber longitudinal strain analysis

8nononeIntroduction: Speckle-tracking echocardiography (STE) has emerged as a ultrasound technique for accurately evaluating myocardial function also in critically ill patients. By tracking the displacement of the speckles during the cardiac cycle, strain rate can be measured offline after adequate image acquisition. The aim of the study was to evaluate the effects of the positive end-expiratory pressure (PEEP) on 4-chamber longitudinal strain (LS) analysis in critically ill patients. Methods: We enrolled 20 consecutive patients (mean age 64±18) who needed mechanical ventilation and were admitted at the Intensive Care Unit due to heterogeneous causes. Inclusion criteria were: hypoxia requiring PEEP titration, invasive arterial pressure monitoring, age>18. Exclusion criteria were: myocardial dysfunction, cardiac arrhythmias and valvular pathologies. The same operator performed three standard echocardiography masurements (MyLab 70 Xvision, Esaote), each of them after having increased PEEP at 5,10, and 15 cmH20 (T1, T2, T3, respectively). Blood gas analysis, respiratory, and hemodynamic parameters provided by a pulse contour method were also recorded. STE analysis was performed off-line (XStrainTMMyLab 70 Xvision, Esaote). Results: Left peak atrial LS (LA-PALS) was significantly reduced from T1 to T2, and from T2 to T3 (40.2±12%, 35.9±9, 28.4±8%, T1, T2, T3, respectively; p<0.05). Right peak atrial LS (RA-PALS) and right ventricular (RV)-LS showed a significant reduction only at T3 (RA-PALS: 44.7±48.5% at T1, 35.9±11% at T3; RV-LS: -20.2±2% at T1, - 16.3±1.1% at T3; p<0.05). Left ventricular (LV)-LS did not change significantly during titration of PEEP. Cardiac chambers’ volumes and cardiac output (CO) showed a significant reduction at higher levels of PEEP. Pulse pressure variation (PPV) was significantly affected by higher levels of PEEP (p<0.05). Conclusions: In hypoxic patients with normal cardiac function, PEEP tritation determined a reduction of LA-, RA- and RV-LS values. LV-LS values were not influenced by PEEP changes. The fall in CO, observed with higher values of PEEP, seemed to be related to the impairement of preload and not of myocardial contractility. Whenever interpreting data on cardiac function obtained with longitudinal strain analysis, attention of clinician should be drawn to different levels of PEEP. The higher the PEEP, the more the probability of misleading interpretation of speckle echocardiographic data.noneFranchi, F.; Cameli, M.; Faltoni, A.; Lisi, M.; Mongelli, P.; Muzzi, L.; Mondillo, S.; Scolletta, S.Franchi, Federico; Cameli, Matteo; Faltoni, A.; Lisi, M.; Mongelli, P.; Muzzi, Luigi; Mondillo, Sergio; Scolletta, Sabin