Preoperative anaemia is associated with elevated risks of postoperative complications. This association may be explained by confounding related to poor cardiopulmonary fitness. We conducted a ...pre-specified substudy of the Measurement of Exercise Tolerance before Surgery (METS) study to examine the associations of preoperative haemoglobin concentration with preoperative cardiopulmonary exercise testing performance (peak oxygen consumption, anaerobic threshold) and postoperative complications.
The substudy included a nested cross-sectional analysis and nested cohort analysis. In the cross-sectional study (1279 participants), multivariate linear regression modelling was used to determine the adjusted association of haemoglobin concentration with peak oxygen consumption and anaerobic threshold. In the nested cohort study (1256 participants), multivariable logistic regression modelling was used to determine the adjusted association of haemoglobin concentration, peak oxygen consumption, and anaerobic threshold with the primary endpoint (composite outcome of death, cardiovascular complications, acute kidney injury, or surgical site infection) and secondary endpoint (moderate or severe complications).
Haemoglobin concentration explained 3.8% of the variation in peak oxygen consumption and anaerobic threshold (P<0.001). Although not associated with the primary endpoint, haemoglobin concentration was associated with moderate or severe complications after adjustment for peak oxygen consumption (odds ratio=0.86 per 10 g L−1 increase; 95% confidence interval, 0.77–0.96) or anaerobic threshold (odds ratio=0.86; 95% confidence interval, 0.77–0.97). Lower peak oxygen consumption was associated with moderate or severe complications without effect modification by haemoglobin concentration (P=0.12).
Haemoglobin concentration explains a small proportion of variation in exercise capacity. Both anaemia and poor functional capacity are associated with postoperative complications and may therefore be modifiable targets for preoperative optimisation.
Impaired cardiac vagal function, quantified preoperatively as slower heart rate recovery (HRR) after exercise, is independently associated with perioperative myocardial injury. Parasympathetic ...(vagal) dysfunction may also promote (extra-cardiac) multi-organ dysfunction, although perioperative data are lacking. Assuming that cardiac vagal activity, and therefore heart rate recovery response, is a marker of brainstem parasympathetic dysfunction, we hypothesized that impaired HRR would be associated with a higher incidence of morbidity after noncardiac surgery.
In two prospective, blinded, observational cohort studies, we established the definition of impaired vagal function in terms of the HRR threshold that is associated with perioperative myocardial injury (HRR ≤ 12 beats min-1 (bpm), 60 seconds after cessation of cardiopulmonary exercise testing. The primary outcome of this secondary analysis was all-cause morbidity three and five days after surgery, defined using the Post-Operative Morbidity Survey. Secondary outcomes of this analysis were type of morbidity and time to become morbidity-free. Logistic regression and Cox regression tested for the association between HRR and morbidity. Results are presented as odds/hazard ratios OR or HR; (95% confidence intervals).
882/1941 (45.4%) patients had HRR≤12bpm. All-cause morbidity within 5 days of surgery was more common in 585/822 (71.2%) patients with HRR≤12bpm, compared to 718/1119 (64.2%) patients with HRR>12bpm (OR:1.38 (1.14-1.67); p = 0.001). HRR≤12bpm was associated with more frequent episodes of pulmonary (OR:1.31 (1.05-1.62);p = 0.02)), infective (OR:1.38 (1.10-1.72); p = 0.006), renal (OR:1.91 (1.30-2.79); p = 0.02)), cardiovascular (OR:1.39 (1.15-1.69); p<0.001)), neurological (OR:1.73 (1.11-2.70); p = 0.02)) and pain morbidity (OR:1.38 (1.14-1.68); p = 0.001) within 5 days of surgery.
Multi-organ dysfunction is more common in surgical patients with cardiac vagal dysfunction, defined as HRR ≤ 12 bpm after preoperative cardiopulmonary exercise testing.
ISRCTN88456378.
The study aims to determine long-term survival, health-related quality of life (HRQoL) and functional and physical outcomes of adult extra corporeal membrane oxygenation (ECMO) patients as there are ...limited and conflicting data in this area.
All patients receiving ECMO from April 2009 until June 2014 at The Prince Charles Hospital, Brisbane had Kaplan Meier survival calculated. Quality of life (QoL) was assessed using the Short Form Health Survey (SF-36v2), EQ5D-5L, The Frenchay Activities Index (FAI) and a return to work survey. From December 2011, these measures and 6-minute walk distance (6MWD) were assessed at hospital discharge and 12 months post-discharge.
Seventy-seven (77) patients (45 veno-arterial and 32 veno-venous) received ECMO of whom 47/77 (61%) survived to hospital discharge. There were no deaths recorded in those discharged alive from the intensive care unit at median follow-up time 1,011days (range 227–2,014 days). Mean SF-36 scores (n=33) and EQ5D were assessed at a median of 606days after hospital discharge. SF-36 scores were significantly (p<0.05) worse than age-matched norms in all domains except vitality, bodily pain and mental health. Thirteen (13) (39%) participants had persistent problems with mobility and usual activity as measured by EQ5D. At 12 months post-ECMO, 6MWD was 531(IQR:397.3–626.8)m; 72% (IQR:53.2–77.6%) predicted but had improved by 223m (p=0.002) when compared to baseline. Nineteen (19) of 20 participants who had been employed pre-ECMO had returned to work.
All ECMO patients discharged from hospital were alive at follow-up. Despite improvements in physical measures and HRQoL, long-term functional deficits persist when compared to that of aged- and sex-matched norms.
Weakly interacting massive particles (WIMPs) may interact with a virtual pion that is exchanged between nucleons. This interaction channel is important to consider in models where the ...spin-independent isoscalar channel is suppressed. Using data from the first science run of the LUX-ZEPLIN dark matter experiment, containing 60 live days of data in a 5.5~tonne fiducial mass of liquid xenon, we report the results on a search for WIMP-pion interactions. We observe no significant excess and set an upper limit of \(1.5\times10^{-46}\)~cm\(^2\) at a 90\% confidence level for a WIMP mass of 33~GeV/c\(^2\) for this interaction.
The Data Acquisition System (DAQ) for the LUX-ZEPLIN (LZ) dark matter detector is described. The signals from 745 PMTs, distributed across three subsystems, are sampled with 100-MHz 32-channel ...digitizers (DDC-32s). A basic waveform analysis is carried out on the on-board Field Programmable Gate Arrays (FPGAs) to extract information about the observed scintillation and electroluminescence signals. This information is used to determine if the digitized waveforms should be preserved for offline analysis. The system is designed around the Kintex-7 FPGA. In addition to digitizing the PMT signals and providing basic event selection in real time, the flexibility provided by the use of FPGAs allows us to monitor the performance of the detector and the DAQ in parallel to normal data acquisition. The hardware and software/firmware of this FPGA-based Architecture for Data acquisition and Realtime monitoring (FADR) are discussed and performance measurements are described.
LUX-ZEPLIN (LZ) is a tonne-scale experiment searching for direct dark matter interactions and other rare events. It is located at the Sanford Underground Research Facility (SURF) in Lead, South ...Dakota, USA. The core of the LZ detector is a dual-phase xenon time projection chamber (TPC), designed with the primary goal of detecting Weakly Interacting Massive Particles (WIMPs) via their induced low energy nuclear recoils. Surrounding the TPC, two veto detectors immersed in an ultra-pure water tank enable reducing background events to enhance the discovery potential. Intricate calibration systems are purposely designed to precisely understand the responses of these three detector volumes to various types of particle interactions and to demonstrate LZ's ability to discriminate between signals and backgrounds. In this paper, we present a comprehensive discussion of the key features, requirements, and performance of the LZ calibration systems, which play a crucial role in enabling LZ's WIMP-search and its broad science program. The thorough description of these calibration systems, with an emphasis on their novel aspects, is valuable for future calibration efforts in direct dark matter and other rare-event search experiments.
The first science run of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time project chamber operating in the Sanford Underground Research Facility in South Dakota, USA, has reported leading ...limits on spin-independent WIMP-nucleon interactions and interactions described from a non-relativistic effective field theory (NREFT). Using the same 5.5~t fiducial mass and 60 live days of exposure we report on the results of a relativistic extension to the NREFT. We present constraints on couplings from covariant interactions arising from the coupling of vector, axial currents, and electric dipole moments of the nucleon to the magnetic and electric dipole moments of the WIMP which cannot be described by recasting previous results described by an NREFT. Using a profile-likelihood ratio analysis, in an energy region between 0~keV\(_\text{nr}\) to 270~keV\(_\text{nr}\), we report 90% confidence level exclusion limits on the coupling strength of five interactions in both the isoscalar and isovector bases.
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