Effect of hyperbilirubinemia on the accuracy of continuous non-invasive hemoglobin measurements in liver transplantation recipients

This study evaluated the effect of hyperbilirubinemia on the accuracy of continuous non-invasive hemoglobin (SpHb) measurements in liver transplantation recipients. Overall, 1465 SpHb and laboratory hemoglobin (Hb) measurement pairs (n = 296 patients) were analyzed. Patients were grouped into normal (< 1.2 mg/dL), mild-to-moderate (1.2-3.0 mg/dL), and severe (> 3.0 mg/dL) hyperbilirubinemia groups based on the preoperative serum total bilirubin levels. Bland-Altman analysis showed a bias of 0.20 (95% limit of agreement, LoA: - 2.59 to 3.00) g/dL, 0.98 (95% LoA: - 1.38 to 3.35) g/dL, and 1.23 (95% LoA: - 1.16 to 3.63) g/dL for the normal, mild-to-moderate, and severe groups, respectively. The four-quadrant plot showed reliable trending ability in all groups (concordance rate > 92%). The rates of possible missed transfusion (SpHb > 7.0 g/dL for Hb < 7.0 g/dL) were higher in the hyperbilirubinemia groups (2%, 7%, and 12% for the normal, mild-to-moderate, and severe group, respectively. all P < 0.001). The possible over-transfusion rate was less than 1% in all groups. In conclusion, the use of SpHb in liver transplantation recipients with preoperative hyperbilirubinemia requires caution due to the positive bias and high risk of missed transfusion. However, the reliable trending ability indicated its potential use in clinical settings.

Continuous cardiac output estimation using a new modified Fick method during off-pump coronary artery bypass graft surgery: a retrospective observational study

PURPOSE

Several technical aspects of the Fick method limit its use intraoperatively. A data-driven modification of the Fick method may enable its use in intraoperative settings.

METHODS

This two-center retrospective observational study included 57 (28 and 29 in each center) patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery. Intraoperative recordings of physiological data were obtained and divided into training and test datasets. The Fick equation was used to calculate cardiac output (CO-Fick) using ventilator-determined variables, intraoperative hemoglobin level, and SvO2, with continuous thermodilution cardiac output (CCO) used as a reference. A modification CO-Fick was derived and validated: CO-Fick-AD, which adjusts the denominator of the original equation.

RESULTS

Increased deviation between CO-Fick and CCO was observed when oxygen extraction was low. The root mean square error of CO-Fick was decreased from 6.07 L/min to 0.70 L/min after the modification. CO-Fick-AD showed a mean bias of 0.17 (95% CI 0.00-0.34) L/min, with a 36.4% (95% CI 30.6-44.4%) error. The concordance rates of CO-Fick-AD ranged from 73.3 to 87.1% depending on the time interval and exclusion zone.

CONCLUSIONS

The original Fick method is not reliable when oxygen extraction is low, but a modification using data-driven approach could enable continuous estimation of cardiac output during the dynamic intraoperative period with minimal bias. However, further improvements in precision and trending ability are needed.

Real-time machine learning model to predict in-hospital cardiac arrest using heart rate variability in ICU

Predicting in-hospital cardiac arrest in patients admitted to an intensive care unit (ICU) allows prompt interventions to improve patient outcomes. We developed and validated a machine learning-based real-time model for in-hospital cardiac arrest predictions using electrocardiogram (ECG)-based heart rate variability (HRV) measures. The HRV measures, including time/frequency domains and nonlinear measures, were calculated from 5 min epochs of ECG signals from ICU patients. A light gradient boosting machine (LGBM) algorithm was used to develop the proposed model for predicting in-hospital cardiac arrest within 0.5-24 h. The LGBM model using 33 HRV measures achieved an area under the receiver operating characteristic curve of 0.881 (95% CI: 0.875-0.887) and an area under the precision-recall curve of 0.104 (95% CI: 0.093-0.116). The most important feature was the baseline width of the triangular interpolation of the RR interval histogram. As our model uses only ECG data, it can be easily applied in clinical practice.

Microneedles coated with composites of phenylboronic acid-containing polymer and carbon nanotubes for glucose measurements in interstitial fluids

A microneedle (MN) sensor coated with a sensing composite material was proposed for measuring glucose concentrations in interstitial fluid (ISF). The sensing composite material was prepared by blending a polymer containing glucose-responsive phenylboronic acid (PBA) moieties (i.e., polystyrene-block-poly(acrylic acid-co-acrylamidophenylboronic acid)) with conductive carbon nanotubes (CNTs). The polymer exhibited reversible swelling behavior in response to glucose concentrations, which influenced the distribution of the embedded CNTs, resulting in sensitive variations in electrical percolation, even when coated onto a confined surface of the MN in the sensor. We varied the ratio of PBA moieties and the loading amount of CNTs in the sensing composite material of the MN sensor and tested them in vitro using an ISF-mimicking gel with physiological glucose concentrations to determine the optimal sensitivity conditions. When tested in animal models with varying blood glucose concentrations, the MN sensor coated with the selected sensing material exhibited a strong correlation between the measured electrical currents and blood glucose concentrations, showing accuracy comparable to that of a glucometer in clinical use.

Perioperative hemodynamic instability in pheochromocytoma and sympathetic paraganglioma patients

For pheochromocytoma and sympathetic paraganglioma (PPGL), surgery can be used as a curative treatment; however, the life-threatening risk of perioperative hemodynamic instability (HI) presents challenges. This study aimed to analyze the incidence and predictive factors of perioperative HI. The electronic medical records of 114 consecutive patients who underwent surgery for PPGLs at our institution were retrospectively reviewed. HI was defined as one or more episodes of systolic blood pressure > 200 mmHg or mean blood pressure < 60 mmHg during surgery. The factors predictive of perioperative HI were determined using both univariate and multivariate analyses. Intraoperative HI occurred in 79 (69.3%) patients. In multivariate analysis, α-adrenergic receptor blocker duration (days) (odds ratio, 1.015; 95% confidence interval, 1.001–1.029) was a predictor for intraoperative HI. Postoperative hypotension occurred in 36 (31.6%) patients. Higher urine epinephrine levels, and greater preoperative highest heart rate (HR) were predictive factors for postoperative hypotension in PPGL patients. Caution should be taken in perioperative management for PPGL, especially with long duration of α-adrenergic receptor blocker use, higher urine epinephrine levels, and greater preoperative highest HR.

Comparison of bispectral index-guided and fixed-gas concentration techniques in desflurane and remifentanil anesthesia: A randomized controlled trial

Anesthesia with desflurane and remifentanil can be maintained with either fixed or titrated desflurane concentration. We hypothesized that the fixed-gas concentration (FG) method would reduce the number of anesthetic titrations without hypnotic and hemodynamic instability compared to the bispectral index (BIS)-guided (BG) method. Forty-eight patients were randomly allocated to the FG or BG groups. In the FG group, desflurane vaporizer setting was fixed at 1 age-corrected minimum alveolar concentration (MAC). In the BG group, desflurane was titrated to target a BIS level at 50. Remifentanil was titrated to maintain a systolic arterial pressure (SAP) of 120 mmHg in both groups. Our primary endpoint was the hypnotic stability measured by the wobble of BIS in performance analysis, and the secondary endpoints included the wobble of SAP, mean BIS value during surgery, and the number of anesthetic titrations. The BIS in the FG group showed significantly less wobble (3.9 ± 1.1% vs 5.5 ± 1.5%, P <0.001) but lower value (33 ± 6 vs 46 ± 7, P <0.001) than BG group. The wobble of SAP showed no difference between groups [median (inter-quartile range), 5.0 (4.1-7.5)% vs 5.2 (4.2-8.3)%, P = 0.557]. The numbers of anesthetic titrations in the FG group were significantly lower than the BG group (0 ± 0 vs 8 ± 5, P<0.001 for desflurane, 13 ± 13 vs 22 ± 17, P = 0.047 for remifentanil). Less wobble in BIS and reduced anesthetic titration without hemodynamic instability during the FG technique may be practical in balanced anesthesia using desflurane and remifentanil anesthesia. Clinical trial: This study was registered at ClinicalTrials.gov (NCT02283866).

Excessive remifentanil during total intravenous anesthesia is associated with increased risk of pain after robotic thyroid surgery

The widespread use of remifentanil during total intravenous anesthesia (TIVA) has raised concerns about the risk of postoperative remifentanil-associated pain. Although a recent meta-analysis suggests that remifentanil-associated pain is unlikely to occur in patients with TIVA because of the protective effect of co-administered propofol, the evidence is not conclusive. We retrospectively assessed 635 patients who received robotic thyroid surgery under TIVA to evaluate the risk of remifentanil-associated pain. Postoperative pain was evaluated using 11-point numeric rating scale (NRS). Time dependent Cox proportional hazards regression analysis was used to determine the risk factors of treatment-requiring pain (NRS > 4) during the first 48 postoperative hours. Postoperative pain rapidly decreased, and treatment-requiring pain remained in 12.8% (81 out of 635) of patients at 48 hours postoperatively. After adjusting for the time-dependent analgesic consumption, intraoperative use of remifentanil > 0.2 mcg/kg/min was a positive predictor of postoperative pain with a hazard ratio of 1.296 (95% C.I., 1.014–1.656, P = 0.039) during 48 hours after surgery. In conclusion, excessive use of remifentanil during TIVA was associated with increased risk of pain after robotic thyroid surgery. Prospective trials are required to confirm these results and determine whether decreasing remifentanil consumption below the threshold can reduce postoperative pain.

Prediction of Acute Kidney Injury after Liver Transplantation: Machine Learning Approaches vs. Logistic Regression Model

Acute kidney injury (AKI) after liver transplantation has been reported to be associated with increased mortality. Recently, machine learning approaches were reported to have better predictive ability than the classic statistical analysis. We compared the performance of machine learning approaches with that of logistic regression analysis to predict AKI after liver transplantation. We reviewed 1211 patients and preoperative and intraoperative anesthesia and surgery-related variables were obtained. The primary outcome was postoperative AKI defined by acute kidney injury network criteria. The following machine learning techniques were used: decision tree, random forest, gradient boosting machine, support vector machine, naïve Bayes, multilayer perceptron, and deep belief networks. These techniques were compared with logistic regression analysis regarding the area under the receiver-operating characteristic curve (AUROC). AKI developed in 365 patients (30.1%). The performance in terms of AUROC was best in gradient boosting machine among all analyses to predict AKI of all stages (0.90, 95% confidence interval [CI] 0.86–0.93) or stage 2 or 3 AKI. The AUROC of logistic regression analysis was 0.61 (95% CI 0.56–0.66). Decision tree and random forest techniques showed moderate performance (AUROC 0.86 and 0.85, respectively). The AUROC of support the vector machine, naïve Bayes, neural network, and deep belief network was smaller than that of the other models. In our comparison of seven machine learning approaches with logistic regression analysis, the gradient boosting machine showed the best performance with the highest AUROC. An internet-based risk estimator was developed based on our model of gradient boosting. However, prospective studies are required to validate our results.

Rac and p38 kinase mediate 5-lipoxygenase translocation and cell death

5-Lipoxygenase (5-LO) is a key enzyme involved in the synthesis of leukotrienes from arachidonic acid, and its activation is usually followed by translocation to the nuclear envelope. The details of mechanisms involved in the translocation of 5-LO are not well understood, though Ca(2+) is known to be essential. Here we show that ionomycin, a Ca(2+) ionophore, induces 5-LO translocation and necrotic cell death in Rat-2 fibroblasts, suggesting a potential relationship between activation of 5-LO and cell death. These effects were markedly attenuated in Rat2-Rac(N17) cells expressing a dominant negative Rac1 mutant. Pretreatment with SB203580, a specific inhibitor of p38 MAP kinase, or EGTA, a Ca(2+) chelator, likewise diminished ionomycin-induced 5-LO translocation and cell death, but PD98059, a MEK inhibitor, did not. Thus, Rac and p38 MAP kinase appear to be components in a Ca(2+)-dependent pathway leading to 5-LO translocation and necrotic cell death in Rat-2 fibroblasts.

Acute gastroparesis in Duchenne's muscular dystrophy

Duchenne's muscular dystrophy (DMD) is an X-linked recessive disease. Clinical descriptions of the disorder focus principally on skeletal muscle degeneration. Another manifestation, which involves the gastrointestinal tract, may be fatal. But its prevalence remains undefined. We report here a case of acute gastroparesis associated with Duchenne's muscular dystrophy. In our case, the patient's symptoms were improved by prokinetic agents and timely decompression in life-threatening acute gastric dilatation.

Localized form of bronchioloalveolar carcinoma: FDG PET findings

OBJECTIVE

The aim of our study was to describe 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) findings of a localized form of bronchioloalveolar carcinoma and to compare those findings with other cell types of lung cancer.

SUBJECTS AND METHODS

FDG PET was performed in 48 patients with lung cancer. The patients had carcinomas of various cell types: bronchioloalveolar carcinoma (n = 9), squamous cell carcinoma (n = 11), adenocarcinoma (n = 22), and other cell types (n = 6). Using FDG PET, we compared peak standardized uptake values among the various cell types of lung cancer. CT and pathologic findings for patients with bronchioloalveolar carcinoma were also reviewed.

RESULTS

Overall, 48 malignant tumors showed a mean peak standardized uptake value of 8.0 +/- 4.1. The mean peak standardized uptake value was 3.5 +/- 2.2 for bronchioloalveolar carcinoma, 10.8 +/- 4.4 for squamous cell carcinoma, and 8.8 +/- 3.2 for adenocarcinoma. The mean peak standardized uptake value for bronchioloalveolar carcinoma was significantly lower than that for adenocarcinoma and squamous cell carcinoma (p < .001). On high-resolution CT scans, bronchioloalveolar carcinomas appeared as areas of ground-glass opacity (n = 4), as nodules (n = 2), as masses (n = 2), and as a ground-glass opacity plus consolidation (n = 1). On pathologic examination, bronchioloalveolar carcinomas were well differentiated, having moderate degrees of nuclear atypism, mild degrees of mitotic figure, desmoplasia, and necrosis.

CONCLUSION

The localized form of bronchioloalveolar carcinoma shows significantly lower peak standardized uptake values than do other lung carcinomas. Thus, bronchioloalveolar carcinoma can be a potential cause of false-negative findings of malignancy on FDG PET scans. When bronchioloalveolar carcinoma is suggested, FDG PET results should be interpreted in combination with high-resolution CT findings.

Carnitine-acylcarnitine translocase in ischemia: evidence for sulfhydryl modification

After coronary occlusion and reflow, carbohydrate catabolism is enhanced, whereas fatty acid utilization is delayed. To test the hypothesis that "stunning" of fatty acid use by ischemic heart reflects reduced fatty acid transport into the mitochondria, two activities involved in the transport were examined: carnitine-acylcarnitine translocase and carnitine palmitoyltransferase II (CPT II). The maximal velocity for carnitine exchange of the translocase is reduced 55% in mitochondria isolated from ischemic canine heart (60-min left circumflex occlusion). Mitochondria from ischemic heart show 50% depletion in total matrix glutathione, a 200% increase in glutathione disulfide (GSSG), and an 80% decrease in the ratio of reduced glutathione (GSH) to GSSG, suggesting that the loss of translocase activity may be a consequence of protein sulfhydryl modifications. In support of this, treatment of these mitochondria with the sulfhydryl-reducing agents, GSH or dithiothreitol, restores carnitine exchange to control. Partial return of mitochondrial GSH and a decrease in GSSG are observed with a 20-min reperfusion of the ischemic myocardium. Continued depression in carnitine exchange with reperfusion suggests that other mechanisms may prevent restoration of activity. Import of palmitoylcarnitine on the translocase is coupled to palmitoyl-CoA production by CPT II. Mitochondria from ischemic heart with decreased coupling activity also have the lowest palmitoylcarnitine-supported respiratory rates, suggesting that in severely ischemic tissue the translocation-transesterification sequence may become rate limiting to fatty acid oxidation.

Protection by verapamil of mitochondrial glutathione equilibrium and phospholipid changes during reperfusion of ischemic canine myocardium

Pretreatment of the ischemic myocardium with verapamil protects against mitochondrial respiratory depression observed during ischemic arrest as well as during reperfusion. Since ischemic mitochondrial function appears not to be altered further by reperfusion, the purpose of this study is to identify a biochemical event affecting mitochondria that is specifically associated with reperfusion injury. It has been proposed that increased cellular Ca2+ influx and oxygen toxicity may result from reintroduction of coronary flow. Increased cytosolic Ca2+ is transmitted to the mitochondria with subsequent activation of Ca2+-dependent events, including phospholipase A2. Net production of lysophospholipids (and loss of total diacylphospholipids from the mitochondria) will proceed when reacylation mechanisms are inhibited. Since acyl-CoA:lysophospholipid acyltransferase is a sulfhydryl-sensitive enzyme and since increased activity of glutathione peroxidase shifts the levels of the mitochondrial sulfhydryl buffer, glutathione, towards oxidation, levels of glutathione and its oxidation state were measured during reperfusion in the absence or presence of verapamil pretreatment. Ischemia lowers total glutathione and reduces the redox ratio (reduced glutathione: oxidized glutathione) by 85%. Reperfusion partially returns the redox ratio to control by causing oxidized glutathione to disappear from the matrix. Verapamil maintains both the concentration and the redox potential of glutathione at control levels. Concomitant with alterations in reduced glutathione:oxidized glutathione is a decrease in ischemic mitochondrial phospholipid content. During reperfusion, phosphatidylethanolamine and its major constituent fatty acids (C 18:0 and C 20:4) are specifically lost from the mitochondrial membrane. Accompanying the significant loss of arachidonic acid during reperfusion is the decreased content of 11-OH, 12-OH, and 15-OH arachidonate. These lipid peroxidation products are not increased in ischemia. It is proposed that oxidation of matrix glutathione to glutathione disulfide during ischemia results in formation of glutathione-protein mixed disulfides and inhibition of sulfhydryl-sensitive proteins, including acyl-CoA lysophosphatide acyltransferase. Thus, metabolic events occurring within the ischemic period set the stage for prolonged dysfunction during reperfusion.

Protection of canine cardiac mitochondrial function by verapamil-cardioplegia during ischemic arrest

Hemodynamic and mitochondrial function recover following 60 minutes of ischemic arrest and reperfusion in hearts pretreated with verapamil. The present study was carried out to determine whether verapamil prevents the onset of mitochondrial oxidative impairment after 60 minutes of ischemic arrest without reperfusion. Two preparations of mitochondria isolated following Polytron homogenization and subsequent treatment of the myofibrillar pellet with Nagarse were examined for phosphorylating respiration. The Polytron mitochondria were more sensitive to ischemic arrest than were the Nagarse mitochondria with either glutamate-malate (57% vs. 22% inhibition), succinate (+ rotenone) (41% vs. 14% inhibition), or palmitoylcarnitine (57% vs. 27% inhibition) as respiratory substrates. Verapamil pretreatment significantly increased oxidation of all substrates by the subsequently isolated Polytron mitochondria, but only succinate-supported respiration returned to control levels. In contrast, the small amount of respiratory inhibition exhibited by the Nagarse mitochondria after ischemic arrest was insensitive to verapamil pretreatment. We conclude that the Polytron preparation of mitochondria is more susceptible to ischemia than the Nagarse mitochondria, and this susceptibility correlates with a striking sensitivity to verapamil protection. In general, oxidation of NADH-linked substrates, including palmitoylcarnitine, is more affected by ischemic arrest than succinate, and only oxidation of the latter substrate is totally protected by verapamil. The beneficial action of verapamil on mitochondrial function occurs prior to reperfusion. The data suggest that alterations in calcium homeostasis occur during the ischemic period, as well as in the subsequent reperfusion period.

Recombination of recessive upsilon+ transformants in Drosophila melanogaster

Recessive transformants (col) obtained fromv(vermilion) embryos treated withv+DNA are shown to map at 1−0·02, a position not distinguishable from that ofsu(s) (suppressor-of-sable) and in agreement with observations indicating phenotypic allelism ofcolwithsu(s) mutants. Recombination in they–col–gtsegment of theXchromosome, over a total map length of O·3 units, was studied among the progeny ofcolv1/y1gtE6cvv1fandy1colgtE6cvv1f/v1females. The data from both crosses exhibit the following features: (1) recovery of reciprocal recombinants betweeny1andcol; (2) recovery of reciprocal recombinants betweencolandgtE6and (3) striking negative interference in they–col–gtsegment. These results allow three alternative interpretations: (1) that recombination in they–col–gtsegment results from conventional crossing-over, with high coincidence of crossovers in the two subsegments; (2) that it results from symmetrical gene conversion at thecolsite (coltocol+, andcol+tocol), which may be accompanied by single cross-overs in either of the adjacent regions; (3) thatcolbehaves like a transposable element, formally symbolizedsu(s)+·col, and that recombination insu(s)+·col/su(s)+(i.e.col/col+) heterozygotes results from transposition of thecolelement from homolog to homolog, accompanied sometimes by crossing-over, either in they–colsubsegment or in thecol-gtsubsegment.

Gene transfer in Drosophila melanogaster: genetic transformations induced by the DNA of transformed stocks

DNA prepared from transformed stocks ofDrosophila melanogasterinduces second-step transformations resembling the original. The gross yield of transformants induced by transformed DNA is several times higher than that induced by the original allo-DNA, but much of this high frequency is attributable to a few exceptionally large clusters of transformants among flies treated with transformed DNA. When these large clusters are omitted from the data, the frequency of transformants induced by DNA from transformed stocks is the same as that induced by allo-DNA. The data therefore support the conclusion that the original DNA-induced alterations resulted from the transfer of genetic material capable of indefinite replication.

DNA-induced transformation in Drosophila: genetic analysis of transformed stocks

The exosome model of transformation in Drosophila melanogaster proposes that DNA fragments enter the cells of treated individuals and become firmly associated with their homologous chromosome segments, but are never integrated into the linear structure of the chromosome. This paper reports results that validate two central predictions of the model: (a) the introduced genetic information usually maps precisely at the site of the target locus, and (b) the original chromosomal information is still present at that site.

DNA-induced transformation in Drosophila: evidence for transmission without integration

A key feature of the exosome model of transformation in Drosophila melanogaster is that the DNA segments responsible for the phenomenon are not integrated into the linear structure of the chromosomes. This feature is confirmed by the failure to find whole-body transformants in a series of large-scale experiments, and by the absence of evidence for integration under conditions favoring genetic exchange between chromosomes and introduced DNA.

DNA-induced transformation in Drosophila: locus-specificity and the establishment of transformed stocks

The genetic changes induced in Drosophila melanogaster by DNA obtained from flies differing at specified genetic loci exhibit the general features of transformation, namely locus specificity and heritability. These properties have provided the basis for the establishment of transformed stocks. The phenomenon also exhibits striking special features, prominent among which is the observation that transformed individuals are always mosaics and that whole-body transformants are absent even in established stocks. The exosome model (which proposes that DNA segments enter the cells of treated individuals and become firmly associated with their homologous chromosome segments, but are never integrated into the linear structure of the chromosome) is formulated to fit these observations.