The prognostic value of elevated neutrophil–lymphocyte ratio for cardiac surgery-associated acute kidney injury: A systematic review and meta-analysis

Background

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil–lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

Methods

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

Results

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18–1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50–3.72). Postoperative NLR measurements were not of prognostic significance.

Conclusions

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.     

Spectrally opponent inputs to the human luminance pathway: slow +M and −L cone inputs revealed by intense long-wavelength adaptation

The nature of the inputs to achromatic luminance flicker perception was explored psychophysically by measuring middle- (M-) and long-wavelength-sensitive (L-) cone modulation sensitivities, M- and L-cone phase delays, and spectral sensitivities as a function of temporal frequency. Under intense long-wavelength adaptation, the existence of multiple luminance inputs was revealed by substantial frequency-dependent changes in all three types of measure. Fast (f) and slow (s) M-cone input signals of the same polarity (+sM and +fM) sum at low frequencies, but then destructively interfere near 16 Hz because of the delay between them. In contrast, fast and slow L-cone input signals of opposite polarity (−sL and +fL) cancel at low frequencies, but then constructively interfere near 16 Hz. Although these slow, spectrally opponent luminance inputs (+sM and −sL) would usually be characterized as chromatic, and the fast, non-opponent inputs (+fM and +fL) as achromatic, both contribute to flicker photometric nulls without producing visible colour variation. Although its output produces an achromatic percept, the luminance channel has slow, spectrally opponent inputs in addition to the expected non-opponent ones. Consequently, it is not possible in general to silence this channel with pairs of 'equiluminant' alternating stimuli, since stimuli equated for the non-opponent luminance mechanism (+fM and +fL) may still generate spectrally opponent signals (+sM and +sL).     

HLA-DR 52- and 51-associated DRB1 alleles in Kenya, East Africa

The genes of the major histocompatibility complex (MHC) are amongst the most polymorphic loci known in the human population. The population genetics of the MHC encoded HLA loci of sub-Saharan Africa are of major interest because of their particular genetic diversity. Here we report on the HLA-DR 52- and 51-associated determinants of the DRB1 loci observed in 165 East African individuals studied in Nairobi, Kenya. The HLA-DR typing was done by serologic and by molecular DNA techniques (PCR-SSOP). The most frequent allele identified was DRB1*1101, followed by DRB1*1503 and DRB1*1302. Some unexpected alleles were repeatedly identified: DRB1*1108, DRB1*1316 and DRB1*1421. Most oftheDR 52-and 51-associated DRB1 alleles were correctly identified by serology as part of the DR3, DR5, DR6 and DR2 groups respectively. The HLA-DRB1 profile reported here corroborates previous genetic and linguistic data supporting the concept that the Eastern African Black population is genetically distinct from other African Black populations. This has important implications in public health issues related to the genetic profile of a population (transplantation, vaccine design for example).     

Neurotransmitter modulation of calcium channels in rat sympathetic neurons.

Adrenergic, cholinergic, and a variety of peptide neurotransmitters are known to modulate Ca currents in peripheral neurons. Using a protocol that allows for simultaneous assessment of effects on dihydropyridine (DHP)-sensitive and DHP-insensitive current components, we compared the actions of norepinephrine (NE), bethanechol (BeCh), and neuropeptide Y (NPY) on Ca currents in neonatal rat superior cervical ganglion neurons. Here, we show that these transmitters selectively depress the activity of DHP-insensitive Ca channels. Intracellular application of GTP-gamma-S, an activator of GTP-binding proteins, also exclusively affected the DHP-insensitive current, whereas 1,2-oleoylacetylglycerol (OAG), a protein kinase C (PKC) activator, depressed both the DHP-sensitive and DHP-insensitive currents. Pertussis toxin interrupted the coupling between NE and its effector, whereas three different inhibitors of PKC did not. Thus, we confirmed that the selective actions of the transmitters on Ca current appear to be mediated via GTP-binding proteins, but we found no evidence for direct involvement of PKC and conclude that the observed actions of OAG are distinct from those mediated by the neurotransmitters studied.     

End-tidal Carbon Dioxide Monitoring during Procedural Sedation

OBJECTIVE: To prospectively determine whether end-tidal carbon dioxide (ETCO2) monitors can detect respiratory depression (RD) and the level of sedation in emergency department (ED) patients undergoing procedural sedation (PS). METHODS: This was a prospective observational study conducted in an urban county hospital of adult patients undergoing PS. Patients were monitored for vital signs, depth of sedation per the physician by the Observer's Assessment of Alertness/Sedation scale (OAA/S), pulse oximetry, and nasal-sample ETCO2 during PS. Respiratory depression was defined as an oxygen saturation <90%, an ETCO2 >50 mm Hg, or an absent ETCO2 waveform at any time during the procedure. The physician also determined whether protective airway reflexes were lost during the procedure and assisted ventilation was required, or whether there were any other complications. Rates of RD were compared with the physician assessment of airway loss and between agents using chi-square statistics. Spearman's rho analysis was used to determine whether there was a correlation between ETCO2 and the OAA/S score. RESULTS: Seventy-four patients were enrolled in the study. Forty (54.1%) received methohexital, 21 (28.4%) received propofol, ten (13.5%) received fentanyl and midazolam, and three (4.1%) received etomidate. Respiratory depression was seen in 33 (44.6%) patients, including 47.5% of patients receiving methohexital, 19% receiving propofol (p = 0.008), 80% receiving fentanyl and midazolam, and 66.6% receiving etomidate. No correlation between OAA/S and ETCO2 was detected. Eleven (14.9%) patients required assisted ventilation at some point during the procedure, all of whom met the criteria for RD. Pulse oximetry detected 11 of the 33 patients with RD. Post-hoc analysis revealed that all patients with RD had an ETCO2 >50 mm Hg, an absent waveform, or an absolute change from baseline in ETCO2 >10 mm Hg. CONCLUSIONS: There was no correlation between ETCO2 and the OAA/S score. Using the criteria of an ETCO2 >50 mm Hg, an absolute change >10 mm Hg, or an absent waveform may detect subclinical RD not detected by pulse oximetry alone. The ETCO2 may add to the safety of PS by quickly detecting hypoventilation during PS in the ED.     

THE INTRODUCTION OF PATIENT-CONTROLLED ANALGESIA INTO AN ISOLATED RURAL HOSPITAL

This study investigated the feasibility of using patient-controlled analgesia (PCA) effectively in a small 70 bed isolated rural hospital. The tirst 50 patients to use a Bard PCA 1, in the Port Lincoln Hospital, South Australia, were studied. The patients consumed morphine at a mean rate of 1.24 mg/h and used PCA for a mean of 48 h. Thirty-eight per cent of patients required treatment for nausea and other complications which is similar to the rate of those in other published series. Visual analogue pain scores showed excellent pain control, generally without evidence of oversedation; however, there was one episode of respiratory depression. Seventy-eight per cent of patients reported that their pain was relieved most or all of the time. The study demonstrated that a PCA service provided by nursing staff, the GP anaesthetist and rural surgeons is feasible in an isolated rural hospital.     

Transmission electron microscopy of free standing thin films of poly(ether ether ketone)

Free standing thin films of poly(ether ether ketone) crystallized in situ by heating from the glassy state have been shown to be suitable for high resolution transmission electron microscopy lattice imaging. Films mounted on coarse-mesh copper grids could also be observed in the deformed state, allowing lattice imaging of regions of strain induced crystallization at temperatures in the neighbourhood of the glass transition temperature.     

Logistic regression in case-control studies: The effect of using independent as dependent variables

In case-control studies, cases are sampled separately from controls. In such studies the primary analysis concerns the estimation of the effect of covariables on being a case or a control. To explore causal pathways, further secondary analysis could concern the relationships among the covariables. In this paper the validity of such secondary analysis is addressed. In particular, the use of multiple logistic regression in case-control studies where the dependent variable is not the case/control indicator is explored. It is shown that only under very restrictive conditions will sample regression coefficients correctly estimate their true value. In many situations, it may be valid to regress one covariable on others in the control group, but not in the case group or the combined sample. This principle is illustrated by a study of sexually transmitted disease in Kenya.