Accuracy of a pulse oximeter in the measurement of the oxyhaemoglobin saturation

The aim of the present study was to evaluate the accuracy, in comparison with a reference method, of the Nellcor N-20P pulse oximeter in the assessment of oxyhaemoglobin saturation (Sa,O2). Sa,O2 was monitored at rest by the Nellcor N-20P pulse oximeter in 100 subjects (82 males, mean age 68+/-12 yrs) consecutively enroled. At the same time, an arterial blood sample was collected for the measurement of Sa,O2, carboxyhaemoglobin, and methaemoglobin by an IL-282 Co-oximeter. A significant difference was found between Sa,O2 values measured with the two methods (t=11.78, p<0.05), but the two series of measurements were significantly correlated (r=0.97). Both the level and the limits of agreement between the two methods were satisfactory when the more appropriate Bland and Altman method was applied. Nevertheless, a lack of accuracy of the pulse oximeter was found, but only for Sa,O2 values <82% and >94%, as demonstrated by the Youden index. In conclusion, these data show that Nellcor N-20P is sufficiently reliable for the assessment and monitoring of oxyhaemoglobin saturation. The lack of accuracy does not seem clinically relevant since it is appreciable only for values at the extremes of the oxyhaemoglobin saturation range.     

A review of the principles of pulse oximetry and accuracy of pulse oximeter estimates during exercise

OBJECTIVE: The outcomes of patients with squamous cell carcinoma of the anal canal treated by either sphincter-preserving procedures or radical surgery were evaluated, with the goals of identifying factors predicting treatment failure and quantifying results of salvage therapy in patients with recurrent disease. BASIC PROCEDURES: A population-based study on all patients in all 159 hospitals of the Department of Veterans Affairs (VA) from 1987 to 1991 was carried out. Data were compiled from several national computerized VA data sets. Supplementary information from local tumor registrars also was obtained, including demographic information, discharge summaries, operative reports, pathology reports, and medical oncology and radiation oncology summaries. From these sources, information on tumor histology, tumor stage, tumor grade, presence of regional or distant metastases, surgical procedures, use of chemotherapy and radiation therapy (RT), toxicity of chemotherapy and RT, development of recurrent disease, treatment of recurrence, survival, and cause of death were obtained. MAIN FINDINGS: Four hundred five patients with anal cancer were identified by computer search, and 204 (51%) were evaluable; 164 of 204 (80%) had squamous cell carcinoma, 137 of whom (84%) were treated with sphincter-preserving procedures, and 27 of whom (16%) were treated by by radical surgery. One hundred fourteen of 138 (83%) were treated by multimodality therapy, which we defined as local excision followed by chemotherapy and RT. The mean dose of RT among patients treated by multimodality therapy was 4200 +/- 540 cGy and 82% of those treated with multimodality therapy received 5-FU/mitomycin C. Recurrent disease was diagnosed in 43 of all 149 patients (29%) with potentially curable disease. (stages I-III) Multivariate analysis revealed that stage at diagnosis (p = 0.04) and method of treatment (p = 0.03) were the sole predictors of recurrence. Fifty-three percent of patients who underwent salvage abdominoperineal resection (APR) are alive, whereas only 19% who underwent salvage chemotherapy with or without RT are alive. PRINCIPAL CONCLUSIONS: These data indicate that multimodality therapy currently is being employed in the majority of patients with squamous cell carcinoma of the anal canal in the VA system. Tumor stage and method of treatment appear to affect the likelihood of development of recurrent disease. Salvage APR has curative potential. Results with salvage chemotherapy and RT are disappointing.     

Clinical evaluation of a prototype motion artifact resistant pulse oximeter in the recovery room

Isolated posterior semicircular canals (psc) of bull frogs were used for a model of positional vertigo. Induced ampullary nerve action potentials were recorded. When the cupula was removed and the saccular otoconia were dropped onto the cilia, excitatory, and inhibitory potentials were evoked by changing the psc positions into canal-down and canal-up, respectively. When the otoconia were allowed to stay on the cupular surface, canal-down and canal-up positions also evoked excitatory and inhibitory responses, respectively. When the otoconia were inserted in the canal and were allowed to move, changing the psc positions likewise evoked responses. However, when one end of the canal was closed, these responses disappeared, indicating the efficacy of canal plugging.     

FIx controller: an instrument to automatically adjust inspired oxygen fraction using feedback control from a pulse oximeter

OBJECTIVE: To develop an instrument to help prevent pulmonary O2 toxicity, a syndrome that manifests itself in adult intensive care patients. METHODS: We designed, built, and tested a device that controls FIO2 exposure using oxygen saturation measured with a pulse oximeter (SpO2) in a negative feedback control system. A target SpO2 is designated by the clinician and the system adjusts the FIO2 from a mechanical ventilator so as to minimize the difference between the measured SpO2 and the target. Important elements of the system include a conservative artifact rejection algorithm, a gainscheduled sampled-data proportional-integral-derivative (PID) controller, and a safety system to prevent inspired mixtures with undesirably low FIO2 due to device failure. RESULTS: The control system was tuned in a series of animal experiments. Acceptable clinical response of the system was obtained using a gain-scheduled controller algorithm whereby the gain of the proportional term of a PID controller was adjusted based on the error signal and measured minute ventilation. Also, the artifact rejection algorithm and safety systems were successfully tested using simulation. CONCLUSIONS: Testing the effectiveness of this instrument will require comparison with manual control of FIO2 in an appropriately designed trial.     

Calibration of a reflectance pulse oximeter in fetal lambs for arterial oxygen saturations below 70%

Today, laparoscopic cholecystectomy is the method of choice for treatment of symptomatic gallbladder disorders. It minimizes effects of the operation that are independent of the gallbladder, such as trauma to the abdominal wall and other soft tissue. The surgical wounds were even smaller when 2-mm trocars were used. Laparoscopic cholecystectomy using 2-mm instruments was performed in a consecutive series of 14 patients with symptomatic gallstones. The procedure was completed in 12 cases, with conversion to open surgery in two cases. Intraoperative cholangiography was always performed. The postoperative course was always uneventful. The cosmetic effect was highly satisfactory. The procedure using 2-mm instruments could be indicated in selected patients with uncomplicated gallstone disease.     

Expanding the role of the neonatal transport nurse: nurse-led teams

Nottingham neonatal service provides a unit-based interhospital transport programme for the stabilization and transportation of critically III neonates within the Trent region. The transport nurse is responsible and accountable for providing optimum care for infants in conjunction with a registrar. The quality of care received by the neonate requiring emergency transfer could be further enhanced by a team of two specifically trained transport nurses.     

How can the clinical credibility of nurse lecturers be improved?: 2

The movement of nurse education into the university sector has put further tension on the theory-practice gap and the clinical credibility of nursing lecturers. If the ideal is for the lecturer to guide the learner in applying theory to practice and vice versa (Jarvis and Gibson, 1985), this can only realistically be achieved if lecturers of nursing have experience as practitioners within the field(s) they teach and are viewed as being clinically credible (ENB, 1996). In the first article (Vol 7(8): 490-2) an innovative way of enabling lecturers of nursing to engage in practice was presented. In this second article a variety of other approaches which enable lecturers to engage in clinical practice will be explored.     

Developing a model of fuzzy logic and a controller to control smelting of copper sulfide concentrate in the Vanyukov furnace

The development of a fuzzy controlling model for smelting copper sulfide concentrate in the Vanyukov furnace of the PV-2 complex of the Zapolyarnyi (Arctic) Branch of OAO GMK Norilskii Nikel’ Copper Plant is presented. A fuzzy model in the form of polynomials and the circuit of a fuzzy controller developed on its basis are given.     

The bone marrow transplant experience through the eyes of a student nurse

Invasion of vascular walls by cancer cells is a well-known phenomenon in lymphoid malignancies. However, its occurrence in epithelial tumors is less well known. This report documents the occurrence of such invasion of vascular walls by an adenocarcinoma of the stomach in a 68-year-old woman. This rare event differs histopathologically from inflammatory vasculitis associated with malignant disease, lymphangitis carcinomatosa, and carcinomatous arteriopathy. In inflammatory vasculitis associated with malignant disease, the main histopathologic feature is fibrinoid necrosis and ordinary pan arteritis-like vasculitis. In lymphangitis carcinomatosa, the main feature is plugging of vascular lumina by tumor cells, a finding not encountered in our case, while in carcinomatosa arteriopathy, the main event is an obliterative fibrointimal hyperplasia, apparently resulting from arterial tumor emboli. In none of these three conditions has direct invasion of vascular walls by tumor cells been previously reported.     

Modelling and control of coiling entry temperature using interval type-2 fuzzy logic systems

Abstract

The set-up of the cooling water applied to the strip as it traverses the runout table in order to achieve the coiler entry temperature was made by an intelligent model implemented using interval type-2 fuzzy logic systems. The model uses as inputs the targets for coiling entry temperature, strip thickness, finish mill exit temperature and finishing mill exit speed. The experiments of this application were carried out for three different types of coil in a real hot strip mill. The results proved the feasibility of the system developed for coiler entry temperature prediction. Comparison with the online type-1 fuzzy logic based model shows that the proposed interval type-2 fuzzy logic system improves performance in coiler entry temperature prediction under the tested condition.     

Application of fuzzy logic techniques for the qualitative interpretation of preferences in a collective questionnaire for users of wheelchairs

Membrane-induced solution structure of human salivary statherin, a 43 amino acid residue acidic phosphoprotein, has been investigated by two-dimensional proton nuclear magnetic resonance (2D 1H NMR) spectroscopy. NMR assignments and structural analysis of this phosphoprotein was accomplished by analyzing the pattern of sequential and medium range NOEs, alphaCH chemical shift perturbations and deuterium exchange measurements of the amide proton resonances. The NMR data revealed three distinct structural motifs in the molecule: (1) an alpha-helical structure at the N-terminal domain comprising Asp1-Tyr16, (2) a polyproline type II (PPII) conformation predominantly occurring at the middle proline-rich domain spanning Gly19-Gln35, and (3) a 3(10)-helical structure at the C-terminal Pro36-Phe43 sequence. Presence of a few weak dalphaN(i,i+2) NOEs suggests that N-terminus also possesses minor population of 3(10)-helical conformation. Of the three secondary structural elements, helical structure formed by the N-terminal residues, Asp1-Ile11 appears to be more rigid as observed by the relatively very slow exchange of amide hydrogens of Glu5-Ile11. 31P NMR experiments clearly indicated that N-terminal domain of statherin exists mainly in disordered state in water whereas, upon addition of structure stabilizing co-solvent, 2,2,2-trifluorethanol (TFE), it showed a strong propensity for helical conformation. Calcium ion interaction studies suggested that the disordered N-terminal region encompassing the two vicinal phosphoserines is essential for the binding of calcium ions in vivo. Results from the circular dichroism (CD) experiments were found to be consistent with and complimentary to the NMR data and provided an evidence that non-aqueous environment such as TFE, could induce the protein to fold into helical conformation. The findings that the statherin possesses blended solvent sensitive secondary structural elements and the requirement of non-structured N-terminal region under aqueous environment in calcium ion interaction may be invaluable to understand various physiological functions of statherin in the oral fluid.     

Determination of substrate specificity for peptide deformylase through the screening of a combinatorial peptide library

Costimulatory molecules are critical in mediating Fas-dependent direct and bystander lysis. In direct lysis, the APC is the Fas-positive target. It presents Ag to the T cell, thereby activating the T cell. The activated T cell then up-regulates FasL, allowing it to kill the APC. In bystander lysis, the APC again induces FasL expression on the T cell, but the target is a third Fas-positive cell that may lack the appropriate MHC-restricting element to activate the T cell. This study shows that ICAM-1 and B7-1 can serve as important adhesion molecules in direct killing using CD4+ T cell effectors. In bystander killing, B7-1 appears to act as a signaling molecule as well. It has been demonstrated that lpr and gld mice are less susceptible to experimental allergic encephalomyelitis than their wild-type counterparts. In this study, we show that although microglia are poor targets of direct killing, they are capable of stimulating myelin basic protein-specific T cells to kill innocent Fas-positive targets. This presents a possible mechanism for the pathogenesis of experimental allergic encephalomyelitis.     

The psychiatric clinical nurse specialist/nurse practitioner: an example of a combined role

The purpose of this article is to provide an historical overview of the clinical nurse specialist and nurse practitioner roles in psychiatric nursing. This article is written as a follow-up to that of Dyer, Hammill, Regan-Kubinski, Yurick, & Kobert, (1997), Archives of Psychiatric Nursing, 11, 2-11, in which a new paradigm for delivering comprehensive mental and general health services is conceptualized, i.e., the psychiatric-primary care nurse practitioner role. In this article an alternative model is presented: the psychiatric clinical nurse specialist/nurse practitioner role. Similarities and differences in the two roles are discussed.     

Predicting intermediate and multiple conclusions in propositional logic inference problems: Further evidence for a mental logic.

This article examines whether a particular mental logic introduced by M. D. S. Braine, B. J. Reiser, and B. Rumain (1984) is a reasonably accurate model of people's logical routines for propositional reasoning. Participants are presented with reasoning problems; to make their reasoning steps explicit, they write down, in order, everything they infer. The inferences predicted by the model are compared with participants' output. Three quarters of participants' responses were predicted, and 85%–90% of the time the output of the model's core inference rules was written down. To predict equally well, L. J. Rips's (1994) mental logic model would need to adopt some of our model's features. The data indicate several problems in the mental models theory and cannot be explained by pragmatic reasoning schemas. Arguments against a mental logic are questioned. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hospital closure: reflections of a former nurse executive

In this interview, a former nurse executive describes her experiences as she participated in the closing of a hospital. She describes the sequence of selected events, some of her feelings, and feelings that were experienced by staff as they continued to provide services while dismantling the organization. She associates these feelings with those that occur in crises associated with stressful events. Recommendations are offered that should be helpful to nurse executives in similar situations.