Homogeneous ventilation is important for prevention of ventilator-induced lung injury. Electrical impedance tomography (EIT) has been used to identify optimal PEEP by detection of homogenous ventilation in non-dependent and dependent lung regions. We aimed to compare the ability of volumetric capnography and EIT in detecting homogenous ventilation between these lung regions. Fifteen mechanically-ventilated patients after cardiac surgery were studied. Ventilator settings were adjusted to volume-controlled mode with a fixed tidal volume (Vt) of 6-8 ml kg(-1) predicted body weight. Different PEEP levels were applied (14 to 0 cm H2O, in steps of 2 cm H2O) and blood gases, Vcap and EIT were measured. Tidal impedance variation of the non-dependent region was highest at 6 cm H2O PEEP, and decreased significantly at 14 cm H2O PEEP indicating decrease in the fraction of Vt in this region. At 12 cm H2O PEEP, homogenous ventilation was seen between both lung regions. Bohr and Enghoff dead space calculations decreased from a PEEP of 10 cm H2O. Alveolar dead space divided by alveolar Vt decreased at PEEP levels ≤6 cm H2O. The normalized slope of phase III significantly changed at PEEP levels ≤4 cm H2O. Airway dead space was higher at higher PEEP levels and decreased at the lower PEEP levels. In postoperative cardiac patients, calculated dead space agreed well with EIT to detect the optimal PEEP for an equal distribution of inspired volume, amongst non-dependent and dependent lung regions. Airway dead space reduces at decreasing PEEP levels.

Introduction The course of the disease in SARS-CoV-2 infection in mechanically ventilated patients is unknown. To unravel the clinical heterogeneity of the SARS-CoV-2 infection in these patients, we designed the prospective observational Maastricht Intensive Care COVID cohort (MaastrICCht). We incorporated serial measurements that harbour aetiological, diagnostic and predictive information. The study aims to investigate the heterogeneity of the natural course of critically ill patients with a SARS-CoV-2 infection. Methods and analysis Mechanically ventilated patients admitted to the intensive care with a SARS-CoV-2 infection will be included. We will collect clinical variables, vital parameters, laboratory variables, mechanical ventilator settings, chest electrical impedance tomography, ECGs, echocardiography as well as other imaging modalities to assess heterogeneity of the course of a SARS-CoV-2 infection in critically ill patients. The MaastrICCht is also designed to foster various other studies and registries and intends to create an open-source database for investigators. Therefore, a major part of the data collection is aligned with an existing national intensive care data registry and two international COVID-19 data collection initiatives. Additionally, we create a flexible design, so that additional measures can be added during the ongoing study based on new knowledge obtained from the rapidly growing body of evidence. The spread of the COVID-19 pandemic requires the swift implementation of observational research to unravel heterogeneity of the natural course of the disease of SARS-CoV-2 infection in mechanically ventilated patients. Our study design is expected to enhance aetiological, diagnostic and prognostic understanding of the disease. This paper describes the design of the MaastrICCht. Ethics and dissemination Ethical approval has been obtained from the medical ethics committee (Medisch Ethische Toetsingscommissie 2020-1565/3 00 523) of the Maastricht University Medical Centre+ (Maastricht UMC+), which will be performed based on the Declaration of Helsinki. During the pandemic, the board of directors of Maastricht UMC+ adopted a policy to inform patients and ask their consent to use the collected data and to store serum samples for COVID-19 research purposes. All study documentation will be stored securely for fifteen years after recruitment of the last patient. The results will be published in peer-reviewed academic journals, with a preference for open access journals, while particularly considering deposition of the manuscripts on a preprint server early. Trial registration number The Netherlands Trial Register (NL8613).

Background: Robot-assisted surgery is considered to improve ergonomics over standard endoscopic surgery. Nevertheless, previous research demonstrated ergonomic deficits in the current console set-up.Aim: This study was designed to objectively assess body posture in the da Vinci console during robot-assisted endoscopic surgery.Methods: Multiple sagittal photographs from six physicians were taken during robot-assisted procedures. Trunk, neck, shoulder, elbow, hip, and knee angles were calculated and compared to ergonomic preferable joint angles. A 2D geometric model was developed using individual anthropometrics. Optimal seat height, armrest height, and viewer height were calculated. These results were compared to the findings of the sagittal photographs.Results: Mean joint angles show potentially harmful neck angles for all participants. Trunk angles vary between surgeons, from inadequate to correct. In short and very tall individuals, optimal armrest height is outside the adjustment range of the console.Conclusion: The da Vinci Surgical System console seating position results in a nonergonomic neck and trunk angle. The developed geometric model revealed that armrest height has a limited adjustment range. Adjustments to the console and optimization of preoperative settings are goals to further improve ergonomics in robot-assisted surgery.

We investigated the accuracy and feasibility of a non-invasive arterial pulse contour technique for continuous measurement of stroke volume (SV) in optimization of atrioventricular (AV) delay in cardiac resynchronization therapy (CRT), by comparing SV changes assessed by Nexfin CO-Trek^® (Nexfin) and echo Doppler aortic velocity-time integral (VTIao). Furthermore, we investigated whether AV-delay optimization increases the effect of CRT when compared with a default AV delay (120 ms). In 23 CRT patients, biventricular pacing (BiVP) was applied at various AV delays, while recording 10 beats preceding BiVP (baseline) and the first 10 BiVP beats, for both methods in parallel. Agreement between Nexfin and VTIao measurements was evaluated (Bland–Altman) on beat-to-beat changes in SV, as well as on effects of BiVP (averaged over 8 beats) at various AV delays. Individual optimal AV delays, for Nexfin (AVopt-n) and VTIao (AVopt-ao), were derived from the second-order polynomial fitted to the effect measurements of 20 patients. In 252 episodes assessed, the difference between measurements (=Nexfin − VTIao) was −0.6 ± 8.1% for beat-to-beat SV changes and −1.3 ± 7.3% for effects of BiVP. Optimal AV delays for Nexfin were well related to AVopt-ao (R²= 0.69). The effect (%) of BiVP at the optimal AV delay was significantly larger than at the default AV delay: median difference (range) being +6.3% (0.1–14.4%; P < 0.001) for VTIao and +4.7% (0.0–14.0%; P < 0.001) for Nexfin. Individual AV optimization increases the effect of CRT. Nexfin is a promising tool in individual CRT optimization, as Nexfin agrees with VTIao on measuring beat-to-beat SV changes and on assessing relative effects of BiVP on SV at various AV delays.

Aims: Sudden cardiac death (SCD) is challenging to predict. Electrocardiogram (ECG)-derived heart rate-corrected QT-interval (QTc) is used for SCD-risk assessment. QTc is preferably determined manually, but vendor-provided automatic results from ECG recorders are convenient. Agreement between manual and automatic assessments is unclear for populations with aberrant QTc. We aimed to systematically assess pairwise agreement of automatic and manual QT-intervals and QTc. Methods and results: A multi-centre cohort enriching aberrant QTc comprised ECGs of healthy controls and long-QT syndrome (LQTS) patients. Manual QT-intervals and QTc were determined by the tangent and threshold methods and compared to automatically generated, vendor-provided values. We assessed agreement globally by intra-class correlation coefficients and pairwise by Bland–Altman analyses and 95% limits of agreement (LoA). Further, manual results were compared to a novel automatic QT-interval algorithm. ECGs of 1263 participants (720 LQTS patients; 543 controls) were available [median age 34 (inter-quartile range 35) years, 55% women]. Comparing cohort means, automatic and manual QT-intervals and QTc were similar. However, pairwise Bland–Altman-based agreement was highly discrepant. For QT-interval, LoAs spanned 95 (tangent) and 92 ms (threshold), respectively. For QTc, the spread was 108 and 105 ms, respectively. LQTS patients exhibited more pronounced differences. For automatic QTc results from 440–540 ms (tangent) and 430–530 ms (threshold), misassessment risk was highest. Novel automatic QT-interval algorithms may narrow this range. Conclusion: Pairwise vendor-provided automatic and manual QT-interval and QTc results can be highly discrepant. Novel automatic algorithms may improve agreement. Within the above ranges, automatic QT-interval and QTc results require manual confirmation, particularly if T-wave morphology is challenging.

Background: Atrial cardiomyopathy (atCM) is an emerging prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy, and capillary density are hallmarks of atCM. The contribution of etiological factors and atrial fibrillation (AF) to the development of differential atCM phenotypes has not been quantified. This study aimed to evaluate the association between histological features of atCM and the clinical phenotype. Methods and Results: We examined left atrial (LA, n=95) and right atrial (RA, n=76) appendages from a European cohort of patients undergoing cardiac surgery. Quantification of histological atCM features was performed following wheat germ agglutinin/CD31/vimentin staining. The contributions of AF, heart failure, sex, and age to histological characteristics were determined with multiple linear regression models. Persistent AF was associated with increased endomysial fibrosis (LA: +1.13±0.47 μm, P =0.038; RA: +0.94±0.38 μm, P =0.041), whereas total extracellular matrix content was not. Men had larger cardiomyocytes (LA: +1.92±0.72 μm, P <0.001), while women had more endomysial fibrosis (LA: +0.99±0.56 μm, P =0.003). Patients with heart failure showed more endomysial fibrosis (LA: +1.85±0.48 μm, P <0.001) and extracellular matrix content (LA: +3.07±1.29%, P =0.016), and a higher capillary density (LA: +0.13±0.06, P =0.007) and size (LA: +0.46±0.22 μm, P =0.044). Fuzzy k‐means clustering of histological features identified 2 subtypes of atCM: 1 characterized by enhanced endomysial fibrosis (LA: +3.17 μm, P <0.001; RA: +2.86 μm, P <0.001), extracellular matrix content (LA: +3.53%, P <0.001; RA: +6.40%, P <0.001) and fibroblast density (LA: +4.38%, P <0.001), and 1 characterized by cardiomyocyte hypertrophy (LA: +1.16 μm, P =0.008; RA: +2.58 μm, P <0.001). Patients with fibrotic atCM were more frequently female (LA: odds ratio [OR], 1.33, P =0.002; RA: OR, 1.54, P =0.004), with persistent AF (LA: OR, 1.22, P =0.036) or heart failure (LA: OR, 1.62, P <0.001). Hypertrophic features were more common in men (LA: OR=1.33, P =0.002; RA: OR, 1.54, P =0.004). Conclusions: Fibrotic atCM is associated with female sex, persistent AF, and heart failure, while hypertrophic features are more common in men.