This study investigated the accuracy, drift, and clinical usefulness of a new optical transcutaneous oxygen tension (tcPO₂) measuring technique, combined with a conventional electrochemical transcutaneous carbon dioxide (tcPCO₂) measurement and reflectance pulse oximetry in the novel transcutaneous OxiVenT™ Sensor. In vitro gas studies were performed to measure accuracy and drift of tcPO₂and tcPCO₂. Clinical usefulness for tcPO₂and tcPCO₂monitoring was assessed in neonates. In healthy adult volunteers, measured oxygen saturation values (SpO₂) were compared with arterially sampled oxygen saturation values (SaO₂) during controlled hypoxemia. In vitro correlation and agreement with gas mixtures of tcPO₂(r= 0.999, bias 3.0 mm Hg, limits of agreement − 6.6 to 4.9 mm Hg) and tcPCO₂(r= 0.999, bias 0.8 mm Hg, limits of agreement − 0.7 to 2.2 mm Hg) were excellent. In vitro drift was negligible for tcPO₂(0.30 (0.63 SD) mm Hg/24 h) and highly acceptable for tcPCO₂(− 2.53 (1.04 SD) mm Hg/12 h). Clinical use in neonates showed good usability and feasibility. SpO₂-SaO₂correlation (r= 0.979) and agreement (bias 0.13%, limits of agreement − 3.95 to 4.21%) in healthy adult volunteers were excellent. The investigated combined tcPO₂, tcPCO₂, and SpO₂sensor with a new oxygen fluorescence quenching technique is clinically usable and provides good overall accuracy and negligible tcPO₂drift. Accurate and low-drift tcPO₂monitoring offers improved measurement validity for long-term monitoring of blood and tissue oxygenation.

Arterial pressure measurements are important to monitor vital function in neonates, and values are known to be dependent of gestational and postnatal age. Current reference ranges for mean arterial pressure in neonates have been derived from small samples and combined data of noninvasive and invasive measurements. We aimed to define reference values for noninvasive mean, systolic, and diastolic blood pressure during the first week of life in otherwise healthy preterm and term neonates defined by gestational and postnatal age. In this retrospective cohort study in a neonatal intensive care unit (NICU) in a Dutch tertiary paediatric hospital, we included the noninvasive blood pressures of neonates admitted between 2016 and 2018, with exclusion of those with severe comorbidities (major cardiac malformations, intracerebral haemorrhage, and tracheal intubation >6 h). We defined the median (P50) with -2 standard deviations (sd) (P0.23), -1 sd (P16), +1 sd (P84), and +2 sd (P97.7) for gestational age and postnatal age using quantile regression, percentiles provided online (http://bloodpressure-neonate.com/). A total of 607 neonates, with 5885 measurements, fulfilled the inclusion criteria. The P50 values of mean noninvasive arterial blood pressure in extreme preterm infants steeply increased during the first day after birth and gradually increased within a week from 27 to 49 mm Hg at 24 h of gestational age, and from 49 to 61 mm Hg at 41 weeks of gestational age. These reference values for noninvasive blood pressure in neonates in the NICU for various gestational age groups provide guidance for clinical decision-making in healthy and diseased neonates during anaesthesia and sedation.

Introduction: Traditional transcutaneous oxygen (tcPO₂) measurements are affected by measurement drift, limiting accuracy and usability. The new potentially drift-free oxygen fluorescence quenching technique has been combined in a single sensor with conventional transcutaneous carbon dioxide (tcPCO₂) monitoring. This study aimed to validate optical tcPO₂ and conventional tcPCO₂ against arterial blood gas samples in preterm neonates and determine measurement drift. Methods: In this prospective observational study, during regular care, transcutaneous measurements were paired to arterial blood gases from preterm neonates aged 24–31 weeks of gestational age (GA) with an arterial catheter. Samples were included based on stability criteria and stratified for sepsis status. Agreement was assessed using the Bland-Altman analysis. Measurement drift per hour was calculated. Results: Sixty-eight premature neonates were included {median (interquartile range [IQR]) GA of 26 4/7 [25 3/7–27 5/7] weeks}, resulting in 216 stable paired samples. Agreement of stable samples in neonates without sepsis (n = 38) and with suspected sepsis (n = 112) was acceptable for tcPO₂ and good for tcPCO₂. However, in stable samples of neonates with sepsis (n = 66), tcPO₂ agreement (bias and 95% limits of agreement) was −32.6 (−97.0 to 31.8) mm Hg and tcPCO₂ agreement was 4.2 (−10.5 to 18.9) mm Hg. The median (IQR) absolute drift values were 0.058 (0.0231–0.1013) mm Hg/h for tcPO₂ and 0.30 (0.11–0.64) mm Hg/h for tcPCO₂. Conclusion: The accuracy of optical tcPO₂ in premature neonates was acceptable without sepsis, while electrochemically measured tcPCO₂ remained accurate under all circumstances. Measurement drift was negligible for tcPO₂ and highly acceptable for tcPCO₂.

Mitochondria are the primary consumers of oxygen and therefore an important location for oxygen availability and consumption measurement. A technique has been developed for mitochondrial oxygen tension (mitoPO₂) measurement, incorporated in the COMET. In contrast to most textbooks, relatively high average mitoPO₂ values have been reported. The first aim of this study was to verify the validity of the COMET calibration for mitoPO₂ measurements in human skin. The second aim was to compare the dynamics of mitoPO₂ to several other techniques assessing tissue oxygenation. Firstly, we performed a two-point calibration. Mitochondrial oxygen depletion was achieved with vascular occlusion. A high mitoPO₂ was reached by local application of cyanide. MitoPO₂ was compared to the arterial oxygen partial pressure (PaO₂). Secondly, for deoxygenation kinetics we compared COMET variables with the LEA O2C, SenTec OxiVenT™ and Medtronic INVOS™ parameters during a vascular occlusion test. 20 healthy volunteers were recruited and resulted in 18 datasets (2 times 9 subjects). The lowest measured mitoPO₂ value per subject had a median [IQR] of 3.0 [1.0–4.0] mmHg, n = 9. After cyanide application the mitoPO₂ was 94.1 mmHg [87.2–110.9] and did not differ significantly (n = 9, p = 0.5) from the PaO₂ of 101.0 [98.0–106.0] mmHg. In contrast to O2C, OxiVenT™ and INVOS parameters, mitoPO₂ declined within seconds with pressure on the probe. The kinetics from this decline are used to mitochondrial oxygen consumption (mitoVO₂). This study validates the calibration of the COMET device in humans. For mitoVO₂ measurements not only blood flow cessation but application of local pressure is of great importance to clear the measurement site of oxygen-carrying erythrocytes.

Background: During laparoscopy, the abdominal cavity is insufflated with carbon dioxide (CO₂) that could become contaminated with viruses and surgical smoke. Medical staff is potentially exposed when this gas leaks into the operating room through the instruments and past trocar valves. No detailed studies currently exist that have quantified these leakage pathways. Therefore, the goal of this study was to quantify the gas leakages through trocars and instruments, during minimally invasive procedures. Methods: A model of the surgical environment was created, consisting of a rigid container with an interface for airtight clamping of laparoscopic equipment such as trocars and surgical instruments. The model was insufflated to 15 mm Hg using a pressure generator and a pneumotachograph measured the equipment gas leak. A protocol of several use cases was designed to simulate the motions and forces the surgeon exerts on the trocar during surgery. Results: Twenty-three individual trocars and twenty-six laparoscopic instruments were measured for leakage under the different conditions of the protocol. Trocar leakages varied between 0 L/min and more than 30 L/min, the instruments revealed a range of leakages between 0 L/min and 5.5 L/min. The results showed that leakage performance varied widely between trocars and instruments and that the performance and location of the valves influenced trocar leakage. Conclusions: We propose trocar redesigns to overcome specific causes of gas leaks. Moreover, an international testing standard for CO₂ leakage for all new trocars and instruments is needed so surgical teams can avoid this potential health hazard when selecting new equipment.

Clinical improvement after red blood cell (RBC) transfusions in preterm infants remains debated. This study aims to investigate the effect of RBC transfusion on the occurrence of desaturations and hypoxia, and other cardiorespiratory outcomes in preterm infants. In this longitudinal observational study, prospectively stored cardiorespiratory parameters of preterm infants who received at least one RBC transfusion between July 2016 and June 2017 were retrospectively analyzed. Sixty infants with 112 RBC transfusions, median GA of 26.7 weeks, were included. The number of desaturations and area < 80% SpO₂ limit, as a measure of the hypoxic burden, were calculated in 24 h before and after RBC transfusion. A mixed effects model was used to account for repeated measurements. Overall, the mean (SE) number of desaturations per hour decreased from 3.28 (0.55) to 2.25 (0.38; p < 0.001), and area < 80% SpO₂ limit decreased from 0.14 (0.04) to 0.08 (0.02) %/s (p = 0.02). These outcomes were stratified for the number of desaturations in 24 h prior to RBC transfusion. The largest effect was observed in the group with the highest mean number of desaturations (≥ 6) prior to RBC transfusion, with a decrease from 7.50 (0.66) to 4.26 (0.38) (p < 0.001) in the number of desaturations and 0.46 (0.13) to 0.20 (0.06) in the area < 80% SpO₂. Perfusion index increased significantly after RBC transfusion (p < 0.001). No other significant effects of RBC transfusion on cardiorespiratory data were observed.Conclusions: RBC transfusions in preterm newborns could help decrease the incidence of desaturations and the area < 80% SpO₂ as a measure of the hypoxic burden. The higher the number of desaturations prior to the RBC transfusion, the larger the effect observed. What is Known:•Red blood cell transfusions potentially prevent hypoxia in anemic preterm infants by increasing the circulatory hemoglobin concentration and improving tissue oxygenation.•There is not a predefined hemoglobin concentration cut-off for the occurrence of symptomatic anemia in preterm infants. What is New:•Oxygen desaturations and hypoxia in anemic preterm infants can be improved by RBC transfusions, especially if more desaturations have occurred before transfusion.•Cardiorespiratory monitor data may help identify infants who will benefit most from red blood cell transfusions.