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Oximetry
Kinds of Oximetry Selected AbstractsFEASIBILITY OF AMBULATORY OVERNIGHT OXIMETRY IN CONSECUTIVE PATIENTS IN A DEMENTIA CLINICJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2005Donald L. Bliwise PhD No abstract is available for this article. [source] Report of an EFNS task force on management of sleep disorders in neurologic disease (degenerative neurologic disorders and stroke)EUROPEAN JOURNAL OF NEUROLOGY, Issue 11 2007P. Jennum A task force to develop guidelines for diagnostic evaluation and treatment of sleep disorders in degenerative neurologic disorders and stroke was initiated by the European Federation of Neurological Societies (EFNS). The aims were to provide evidence-based recommendations in the management of sleep disorders associated with degenerative neurologic disorders and stroke. Neurological patients often have significant sleep disorders like sleep-related breathing disorders (SBD), insomnia, sleep-related motor and rapid eye movement behavioral disorders affecting nocturnal sleep and daytime function. A polysomnography (PSG) is usually a diagnostic minimum for the diagnoses of the most commonly reported sleep disorders in patients with neurologic diseases. A full video-PSG/video-EEG-PSG should be considered in patients with nocturnal motor and/behavior manifestations. Respiratory polygraphy has a moderate sensitivity and specificity in the diagnosis of SBD without neurologic diseases, but its value in patients with neurologic diseases has not been evaluated. Oximetry has a poor sensitivity-specificity for the identification of SDB. Continuous and bi-level positive airway pressure devices are the most effective treatment of SDB in patients with neurologic diseases. There is a need for further studies focusing on the diagnostic procedures and treatment modalities in patients with sleep disorders and degenerative neurologic diseases and stroke. [source] The Use of Cerebral Oximetry as a Monitor of the Adequacy of Cerebral Perfusion in a Patient Undergoing Shoulder Surgery in the Beach Chair PositionPAIN PRACTICE, Issue 4 2009Gregory W. Fischer MD Abstract Four cases of ischemic injury have been reported in patients undergoing orthopedic surgery in the upright position. We describe the use of cerebral oximetry as a monitor of the adequacy of cerebral perfusion in a 63-year-old woman who underwent arthroscopic rotator cuff surgery in a beach chair under general anesthesia. During positioning, a decrease in blood pressure was accompanied by a decrease in cerebral oxygen saturation (SctO2) and was treated with phenylephrine. When spontaneous ventilation resumed, an increase in end-tidal carbon dioxide was accompanied by an increase in SctO2. Cerebral oximetry may prove useful as a guide monitor and manage nonsupine patients. [source] Extending the WHO ,Safe Surgery Saves Lives' project through Global OximetryANAESTHESIA, Issue 10 2009A. F. Merry First page of article [source] The Significance of Pulse Oximetry in the Diagnosis of Pacemaker Failure to OutputANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2010Athanasios Michailidis M.D. In a routine monitor electrocardiogram few hours after implantation of a dual-chamber pacemaker, there was a suspicion of ventricular oversensing leading to failure to output. Pulse oximeter plethysmographic wave signal virtually excluded this suspicion. This case report demonstrates the clinical utility of initial pulse oximeter wave analysis in excluding pacemaker failure to output. Ann Noninvasive Electrocardiol 2010;15(3):293,295 [source] Use of Cerebral Oximetry for Monitoring Cardiac Output During Off-Pump Implantation of Jarvik 2000 Left Ventricular Assist DeviceARTIFICIAL ORGANS, Issue 3 2010Helena Argiriadou MD No abstract is available for this article. [source] Intravenous lidocaine for status epilepticus during childhoodDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2006Shin-ichiro Hamano MD; The clinical efficacy of lidocaine for convulsive status epilepticus in 53 convulsive episodes was examined in 37 children (17 males, 20 females). Mean age of patients receiving lidocaine was 3 years 7 months (SD 3y 5mo). Lidocaine administration achieved control of status epilepticus in 19 of 53 convulsive episodes (35.8%). Seizures ceased within 5 minutes of lidocaine administration in all 19 patients who were responsive to the drug. Regarding aetiology of status epilepticus and types of seizures, there was no statistical difference in effectiveness. Mild decrease of oxygen saturation, monitored by pulse oximetry, was observed in one patient, which improved by oxygenation using a mask. Lidocaine is a useful anticonvulsive agent; however, the response rate to lidocaine appears to be quite low, as less than half of the seizures were effectively controlled by lidocaine. Favourable properties of the drug include prompt responses, less alteration of consciousness, and fewer adverse effects, including less respiratory depression. [source] Bispectral Electroencephalographic Analysis of Patients Undergoing Procedural Sedation in the Emergency DepartmentACADEMIC EMERGENCY MEDICINE, Issue 6 2003James R. Miner MD Abstract Objective: To determine whether there is a correlation between the level of sedation achieved during procedural sedation (PS) in the emergency department as determined by bispectral electroencephalographic (EEG) analysis (BIS) and the rate of respiratory depression (RD), the patient's perception of pain, recall of the procedure, and satisfaction. Methods: This was a prospective observational study conducted in an urban county hospital of adult patients undergoing PS using propofol, methohexital, etomidate, and the combination of fentanyl and midazolam. Consenting patients were monitored by vital signs, pulse oximetry, nasal-sample end-tidal carbon dioxide (ETCO2), and BIS monitors during PS. Respiratory depression (RD) was defined as an oxygen saturation <90%, a change from baseline ETCO2 of >10 mm Hg, or an absent ETCO2 waveform at any time during the procedure. After the procedure, patients were asked to complete three 100-mm visual analog scales (VASs) concerning their perception of pain, recall of the procedure, and satisfaction with the procedure. Patients were divided into four groups based on the lowest BIS score recorded during the procedure, group 1, >85; group 2, 70,85; group 3, 60,69; group 4, <60. Rates of RD and VAS outcomes were compared between groups using chi-square statistics. Results: One hundred eight patients were enrolled in the study. No serious adverse events were noted. RD was seen in three of 14 (21.4%) of the patients in group 1, seven of 34 (20.6%) in group 2, 16 of 26 (61.5%) in group 3, and 18 of 34 (52.9%) in group 4. The rate of RD in patients in group 2 was not significantly different from that in group 1 (p = 0.46). The rate of RD in group 2 was significantly lower than that in groups 3 (p = 0.0003) and 4 (p = 0.006). For the VAS data, when group 1 was compared with the combined groups 2, 3, and 4, it had significantly higher rates of pain (p = 0.003) and recall (p = 0.001), and a dissatisfaction rate (p = 0.085) that approached significance. When groups 2, 3, and 4 were compared with chi-square test, there was not a significant difference in pain (p = 0.151), recall (p = 0.27), or satisfaction (p = 0.25). Conclusions: Patients with a lowest recorded BIS score between 70 and 85 had the same VAS outcomes as more deeply sedated patients and the same rate of RD as less deeply sedated patients. This range of scores represented the optimally sedated patients in this study. [source] Determination of pulp vitality in vivo with pulse oximetryINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2008E. Calil Abstract Aim, To evaluate the use of pulse oximetry as a test for pulp vitality, by comparing in the same patient, the levels of oxygen saturation of the index finger and of the maxillary central incisor and canine teeth without clinically detectable pulp inflammation. Methodology, Seventeen male and female patients aged between 26 and 38 years participated and a total of 32 maxillary central incisor and 32 canine teeth were analysed. Selection criteria required the teeth to have healthy crowns, or with restorations no more than 2 mm in diameter and no clinical and radiographical signs or symptoms of pulp or periapical inflammatory changes. The negative control group consisted of 10 root filled teeth. Measurements were first taken from the index finger of patients. Their teeth were then subjected to a thermal test with refrigerant gas and then to a vitality test with pulse oximetry. Data were analysed by Pearson's and paired t- tests. Results, There were no significant statistical correlations between blood oxygen levels in the index finger and in the teeth of the patient (P > 0.05). There was a statistically significant difference in the oxygen levels between the two tooth groups studied and the index finger (P , 0.002). Mean oxygen values in the index finger of patients were 95% (SD = 1.6), oxygen values in the maxillary central incisor were 91.29% (SD = 2.61) and mean oxygen values in maxillary canine were 90.69% (SD = 2.71). Conclusion, The method determined consistently the level of blood oxygen saturation of the pulp in maxillary central incisor and canine teeth and can therefore be used for pulp vitality testing. Further studies are required to assess the effectiveness and validity of pulse oximetry in determining pulp vitality in traumatized teeth. [source] Trends in hospital-based management of acute asthma from a teaching hospital in South AsiaINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 8 2005S. F. Hussain Summary The aim of this study is to evaluate the hospital-based management of acute asthma in south Asia and to compare practices over a 10-year period. Adult patients (n = 102) admitted at a teaching hospital with acute asthma were studied. Documentation of precipitating factors, family history and physical signs were inadequate in more than half of patients. Pulse oximetry was documented in 95 (93%) patients, but peak flow monitoring was performed only in 50 (49%) patients. Ten-year trend showed deterioration in history and physical examination skills, under use of peak flow readings, and poor pre-discharge instructions. Some aspects of improved care included frequent use of pulse oximeter, preference of inhaled over systemic bronchodilators and increased use of systemic steroids. Significant deficiencies were identified in hospital-based management of acute asthma. Most aspects of asthma care continued to fall short of asthma guidelines. [source] The role of nurses in preventing adverse events related to respiratory dysfunction: literature reviewJOURNAL OF ADVANCED NURSING, Issue 6 2005Julie Considine BN MN RN RM FRCNA Aims., This paper reports a literature review examining the relationship between specific clinical indicators of respiratory dysfunction and adverse events, and exploring the role of nurses in preventing adverse events related to respiratory dysfunction. Background., Adverse events in hospital are associated with poor patient outcomes such as increased mortality and permanent disability. Many of these adverse events are preventable and are preceded by a period during which the patient exhibits clearly abnormal physiological signs. The role of nurses in preserving physiological safety by early recognition and correction of physiological abnormality is a key factor in preventing adverse events. Methods., A search of the Medline and CINAHL databases was conducted using the following terms: predictors of poor outcome, adverse events, mortality, cardiac arrest, emergency, oxygen, supplemental oxygen, oxygen therapy, oxygen saturation, oxygen delivery, assessment, patient assessment, physical assessment, dyspnoea, hypoxia, hypoxaemia, respiratory assessment, respiratory dysfunction, shortness of breath and pulse oximetry. The papers reviewed were research papers that demonstrated a relationship between adverse events and various clinical indicators of respiratory dysfunction. Results., Respiratory dysfunction is a known clinical antecedent of adverse events such as cardiac arrest, need for medical emergency team activation and unplanned intensive care unit admission. The presence of respiratory dysfunction prior to an adverse event is associated with increased mortality. The specific clinical indicators involved are alterations in respiratory rate, and the presence of dyspnoea, hypoxaemia and acidosis. Conclusions., The way in which nurses assess, document and use clinical indicators of respiratory dysfunction is influential in identifying patients at risk of an adverse event and preventing adverse events related to respiratory dysfunction. If such adverse events are to be prevented, nurses must not only be able to recognise and interpret signs of respiratory dysfunction, but must also take responsibility for initiating and evaluating interventions aimed at correcting respiratory dysfunction. [source] Noninvasive Control of Adequate Cerebral Oxygenation During Low-Flow Antegrade Selective Cerebral Perfusion on Adults and Infants in the Aortic Arch SurgeryJOURNAL OF CARDIAC SURGERY, Issue 5 2008Álvaro Rubio M.D. Background: Aortic arch repair techniques using low-flow antegrade selective cerebral perfusion have been standardized to a certain degree. However, some of the often-stated beneficial effects have never been proven. Especially, the existence of an adequate continuous flow in both cerebral hemispheres during the surgical procedure still remains unclear as the monitoring of an effective perfusion remains a nonstandardized technique. Methods: Seventeen patients underwent surgical reconstruction of the aortic arch due to aortic aneurysm surgery (adult group n = 8 patients) or of the hypoplastic aortic arch due to hypoplastic left heart syndrome (HLHS) or aortic coarctation (infant group n = 9 patients) under general anesthesia and mild hypothermia (adult group 28 °C; infant group 25 °C). Mean weights were 92.75 ± 14.00 kg and 4.29 ± 1.32 kg, and mean ages were 58.25 ± 10.19 years and 55.67 ± 51.11 days in the adult group and the infant group, respectively. The cerebral O2 saturation measurement was performed by continuous plotting of the somatic reflectance oximetry of the frontal regional tissue on both cerebral hemispheres (rSO2, INVOS®; Somanetics Corporation, Troy, MI, USA). Results: During low-flow antegrade perfusion via innominate artery, continuous plots with similar values of O2 saturation (rSO2) in both cerebral hemispheres were observed, whereas a decrease in the rSO2 values below the desaturation threshold correlated with a displacement or an incorrect positioning of the arterial cannula in the right subclavian artery. Conclusions: Continuous monitorization of the cerebral O2 saturation during aortic arch surgery in adults and infants is a feasible technique to control an adequate cannula positioning and to optimize clinical outcomes avoiding neurological complications related to cerebral malperfusion. [source] Comparison between intubation and the laryngeal mask airway in moderately obese adultsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2009M. ZOREMBA Background: Obesity is a well-established risk factor for perioperative pulmonary complications. Anaesthetic drugs and the effect of obesity on respiratory mechanics are responsible for these pathophysiological changes, but tracheal intubation with muscle relaxation may also contribute. This study evaluates the influence of airway management, i.e. intubation vs. laryngeal mask airway (LMA), on postoperative lung volumes and arterial oxygen saturation in the early postoperative period. Methods: We prospectively studied 134 moderately obese patients (BMI 30) undergoing minor peripheral surgery. They were randomly assigned to orotracheal intubation or LMA during general anaesthesia with mechanical ventilation. Premedication, general anaesthesia and respiratory settings were standardized. While breathing air, we measured arterial oxygen saturation by pulse oximetry. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 0.5, 2 and 24 h after extubation, with the patient supine, in a 30° head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t -test analysis. Statistical significance was considered to be P<0.05. Results: Postoperative pulmonary mechanical function was significantly reduced in both groups compared with preoperative values. However, within the first 24 h, lung function tests and oxygen saturation were significantly better in the LMA group (P<0.001; ANOVA). Conclusions: In moderately obese patients undergoing minor surgery, use of the LMA may be preferable to orotracheal intubation with respect to postoperative saturation and lung function. [source] The use of pulse oximetry in patients with poor peripheral perfusionACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009S. M. Neustein No abstract is available for this article. [source] Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatricsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2009I. SAADAWY Background: Dexmedetomidine (DEX) is a highly selective ,2 -adrenoceptor agonist that has been used increasingly in children. However, the effect of caudal DEX has not been evaluated before in children. This prospective randomized double-blinded study was designed to evaluate the analgesic efficacy of caudal DEX with bupivacaine in providing pain relief over a 24-h period. Methods: Sixty children (ASA status I) aged 1,6 years undergoing unilateral inguinal hernia repair/orchidopexy were allocated randomly to two groups (n=30 each). Group B received a caudal injection of bupivacaine 2.5 mg/ml, 1 ml/kg; Group BD received the same dose of bupivacaine mixed with DEX 1 ,g/kg during sevoflurane anesthesia. Processed electroencephalogram (bispectral index score), heart rate, blood pressure, pulse oximetry and end-tidal sevoflurane were recorded every 5 min. The characteristics of emergence, objective pain score, sedation score and quality of sleep were recorded post-operatively. Duration of analgesia and requirement for additional analgesics were noted. Results: The end-tidal sevoflurane concentration and the incidence of agitation were significantly lower in the BD group (P<0.05). The duration of analgesia was significantly longer (P<0.001) and the total consumption of rescue analgesic was significantly lower in Group BD compared with Group B (P<0.01). There was no statistically significant difference in hemodynamics between both groups. However, group BD had better quality of sleep and a prolonged duration of sedation (P<0.05). Conclusion: Caudal DEX seems to be a promising adjunct to provide excellent analgesia without side effects over a 24-h period. It has the advantage of keeping the patients calm for a prolonged time. Implications statement: Caudally administered DEX (1 ,g/kg), combined with bupivacaine, was associated with an extended duration of post-operative pain relief. [source] Deceptive simplicity: Systemic oxygen delivery and pulse oximetryJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 7-8 2007Clare L Collins Abstract: Pulse oximetry is often perceived to be a measure of the adequacy of oxygen delivery. It is, however, only a measure of oxygen bound to haemoglobin. Systemic oxygen delivery is principally determined by cardiac output, haemoglobin concentration and haemoglobin saturation. Changes to both cardiac output and haemoglobin concentration will significantly alter oxygen delivery without changing oxygen saturation. This article will describe the components of systemic oxygen delivery and the physiologic limitation of pulse oximetry and caution against over-interpretation of oximetry in the care of newborns. [source] Respiration can be monitored by photoplethysmography with high sensitivity and specificity regardless of anaesthesia and ventilatory modeACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2005L. Nilsson Background:, Photoplethysmography (PPG) is a non-invasive optical technique used, for instance, in pulse oximetry. Beside the pulse synchronous component, PPG has a respiratory synchronous variation (PPGr). Efforts have been made to utilize this component for indirect monitoring of respiratory rate and volume. Assessment of the clinical usefulness as well as of the physiological background of PPGr is required. We evaluated if anaesthesia and positive-pressure ventilation would affect PPGr. Methods:, We recorded reflection mode PPGr, at the forearm, and the respiratory synchronous changes in central venous pressure (CVP), peripheral venous pressure (PVP) and arterial blood pressure (ABP) in 12 patients. Recordings for each patient were made on three occasions: awake with spontaneous breathing; anaesthetized with spontaneous breathing; and anaesthetized with positive-pressure ventilation. We analyzed the sensitivity, specificity, coherence and time relationship between the signals. Results:, PPGr sensitivity for breath detection was [mean (SD)] >86(21)% and specificity >96(12)%. Respiratory detection in the macrocirculation (CVP, PVP and ABP) showed a sensitivity >83(29)% and specificity >93(12)%. The coherence between signals was high (0.75,0.99). The three measurement situations did not significantly influence sensitivity, specificity or time shifts between the PPGr, PVP, ABP, and the reference CVP signal despite changes in physiological data between measurements. Conclusion:, A respiratory synchronous variation in PPG and all invasive pressure signals was detected. The reflection mode PPGr signal seemed to be a constant phenomenon related to respiration regardless of whether or not the subject was awake, anaesthetized or ventilated, which increases its clinical usefulness in respiratory monitoring. [source] Cost-effectiveness of screening for hepatopulmonary syndrome in liver transplant candidates,LIVER TRANSPLANTATION, Issue 2 2007D. Neil Roberts The hepatopulmonary syndrome (HPS) is present in 15,20% of patients with cirrhosis undergoing orthotopic liver transplantation (OLT) evaluation. Both preoperative and post-OLT mortality is increased in HPS patients particularly when hypoxemia is severe. Screening for HPS could enhance detection of OLT candidates with sufficient hypoxemia to merit higher priority for transplant and thereby decrease mortality. However, the cost-effectiveness of such an approach has not been assessed. Our objective was to perform a cost-effectiveness analysis from a third-party payer's perspective of screening for HPS in liver OLT candidates. The costs and outcomes of 3 different strategies were compared: (1) no screening, (2) screening patients with a validated dyspnea questionnaire, and (3) screening all patients with pulse oximetry. Arterial blood gas analyses and contrast echocardiography were performed in patients with dyspnea or a pulse oximetry (SpO2) ,97% to define the presence of HPS. A Markov model was constructed simulating the natural history of cirrhosis in a cohort of patients 50 years old over a time horizon of their remaining life expectancy. Transition probabilities were obtained from published data available through Medline and U.S. vital statistics. Costs represented Medicare reimbursement data at our institution. Costs and health effects were discounted at a 3% annual rate. No screening was associated with a total cost of $291,898 and a life expectancy of 11.131 years. Screening with pulse oximetry was associated with a cost of $299,719 and a life expectancy of 12.27 years. Screening patients with the dyspnea-fatigue index was associated with a cost and life expectancy of $300,278 and 12.28 years, respectively. The incremental cost-effectiveness ratio of screening with pulse oximetry (compared to no screening) was $6,867 per life year gained, whereas that of the dyspnea-fatigue index (compared to pulse oximetry) was $55,900 per life year gained. The cost-effectiveness of screening depended on the prevalence and severity of HPS, and the choice of screening strategy was dependent on the sensitivity of the screening modality. In conclusion, screening for HPS, especially with pulse oximetry, is a cost-effective strategy that improves survival in transplant candidates predominantly by targeting the transplant to the subgroup of patients most likely to benefit. The utility of screening depends on the prevalence and severity of HPS in the target population. Liver Transpl, 2006. © 2006 AASLD. [source] Utility of pulse oximetry in the detection of arterial hypoxemia in liver transplant candidatesLIVER TRANSPLANTATION, Issue 4 2002Gary A. Abrams MD Assistant Professor of Medicine Hepatopulmonary syndrome, arterial hypoxemia caused by intrapulmonary vasodilatation, occurs in approximately 10% of patients with cirrhosis. The severity of hypoxemia affects liver transplant candidacy and is associated with increased morbidity and mortality posttransplantation. Screening guidelines for detecting the presence of arterial hypoxemia do not exist. The aim of this study is to investigate the accuracy and utility of pulse oximetry in the detection of hypoxemia (PaO2 < 70 mm Hg) in patients with cirrhosis. Two hundred prospective liver transplant candidates were compared with 94 controls. Arterial oxyhemoglobin saturation was obtained by pulse oximetry (SpO2) and compared with simultaneous arterial blood gas (ABG) oxyhemoglobin values (SaO2; bias = the difference). PaO2, carboxyhemoglobin, methemoglobin, and routine clinical and biochemical parameters were investigated to account for the bias. SpO2 overestimated SaO2 in 98% of patients with cirrhosis (mean bias, 3.37%; range, ,1% to 10%). Forty-four percent of patients with cirrhosis and controls had a bias of 4% or greater. No clinical or biochemical parameters of cirrhosis accounted for the overestimation of pulse oximetry. Twenty-five subjects with cirrhosis were hypoxemic, and an SpO2 of 97% or less showed a sensitivity of 96% and a positive likelihood ratio of 3.9 for detecting hypoxemia. An SpO2 of 94% or less detected all subjects with an arterial PaO2 less than 60 mm Hg. Pulse oximetry significantly overestimates arterial oxygenation, and the inaccuracy is not influenced by liver disease. Nevertheless, pulse oximetry can be a useful screening tool to detect arterial hypoxemia in patients with cirrhosis, but a higher threshold for obtaining an ABG must be used. [source] Carbon blacks as EPR sensors for localized measurements of tissue oxygenationMAGNETIC RESONANCE IN MEDICINE, Issue 6 2004Minbo Lan Abstract New electron paramagnetic resonance (EPR) oximetry probes were identified in the class of carbon black materials. These compounds exhibit very high oxygen sensitivity and favorable EPR characteristics for biological applications. At low pO2, the linewidth is particularly sensitive to changes in oxygen tension (sensitivity of 750 mG/mmHg). The application of the probes for oximetry was demonstrated in vivo: the pO2 was measured in muscle in which the blood flow was temporarily restricted as well as in tumor-bearing mice during a carbogen breathing challenge. The responsiveness to pO2 was stable in muscle for at least 3 months. No toxicity was observed using these materials in cellular experiments and in histological studies performed 2, 7, and 28 days after implantation. In view of their EPR characteristics (high sensitivity) as well as the well-characterized production procedure that make them available on a large scale, these probes can be considered as very promising tools for future developments in EPR oximetry. Magn Reson Med 51:1272,1278, 2004. © 2004 Wiley-Liss, Inc. [source] EPR oximetry in the beating heart: Myocardial oxygen consumption rate as an index of postischemic recoveryMAGNETIC RESONANCE IN MEDICINE, Issue 4 2004Govindasamy Ilangovan Abstract Oxygen plays a critical role in the pathophysiology of myocardial injury during both ischemia and subsequent reperfusion (I/R). Thus, oxygen concentration is an important variable to measure during I/R. In the present work, electron paramagnetic resonance (EPR)-based oximetry was used to measure the oxygen concentration during a series of I/R episodes and oxygenation levels were correlated with the contractile and hemodynamic functions of the heart. A custom-developed electronically tunable surface coil resonator working at 1.1 GHz was used to determine tissue pO2 in the beating heart. Microcrystalline particulate of lithium phthalocyanine was used as an EPR oximetry probe. Isolated and perfused rat hearts were subjected to 1 or 3 hr durations of preischemic perfusion, followed by 15-min I/R cycles. In hearts perfused for 3 hr prior to 15-min I/R cycles, the myocardial pO2 decreased gradually on subsequent reperfusions of three successive I/R cycles. However, in hearts perfused for 1 hr there was almost 100% recovery of myocardial pO2 in all three I/R cycles. The extent of oxygenation recovered in each reperfusion cycle correlated with the recovery of hemodynamic and contractile function. The results also showed that the oxygen consumption rate of the heart at the end of each I/R episode decreased in direct proportion to the functional recovery. In summary, it was observed that the amount of myocardial oxygen consumption during I/R could provide a reliable index of functional impairment in the heart. Magn Reson Med 51:835,842, 2004. © 2004 Wiley-Liss, Inc. [source] Continuous spinal analgesia for labor and delivery in a parturient with hypertrophic obstructive cardiomyopathyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2002T. Okutomi Induction of labor under analgesia was planned for a 30-year-old-primiparous patient with hypertrophic obstructive cardiomyopathy (HOCM), as her fetal evaluation revealed intrauterine growth restriction at 38 weeks' gestation. However, regional analgesia during labor may present a potential risk for hemodynamic instability in patients with HOCM due to the possibility of a sympathetic block, as a result of vasodilation associated with the administration of local anesthesia. This case report demonstrates the successful management of the patient with analgesia provided by a continuous spinal catheter dosed with a continuous infusion of fentanyl and supplemental meperidine. Fetal surveillance monitoring included fetal pulse oximetry in addition to conventional cardiotocography, on the basis of which cesarean section was avoided. [source] Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applicationsNMR IN BIOMEDICINE, Issue 5 2004Bernard Gallez Abstract This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Tubeless combined high-frequency jet ventilation for laryngotracheal laser surgery in paediatric anaesthesiaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2000G. Ihra Background: High-frequency jet ventilation (HFJV) is an alternative ventilatory approach in airway surgery and for facilitating gas exchange in patients with pulmonary insufficiency. We have developed a new technique of combined HFJV utilising two superimposed jet streams. In this study we describe the application of tubeless supralaryngeal HFJV during laryngotracheal laser surgery in infants and children. Methods: Tubeless combined HFJV characterised by the simultaneous supralaryngeal application of a low-frequency (LF) and a high-frequency (HF) jet stream was evaluated in a clinical study in 10 children undergoing elective laryngotracheal CO2 laser surgery. Additionally, pressure and flow characteristics were determined with the use of a paediatric test lung. HFJV was applied by means of a modified Kleinsasser laryngoscope with integrated metal injectors. In addition to pulse oximetry, monitoring of ECG, heart rate and blood pressure, supraglottic airway pressure was measured and arterial blood gases were analysed. Results: Tubeless combined HFJV was used in 10 infants and children (mean age 4.6 yr, range 2 months,10 years) undergoing 17 consecutive endoscopic procedures with CO2 laser microsurgery of the larynx or the trachea under general anaesthesia. The mean duration of supralaryngeal HFJV was 46 min (range 15,75 min). Mean driving pressures of the HF and the LF jet streams were 0.75 bar and 0.95 bar, respectively. Inspiratory oxygen ratios were in the range 0.4,1.0. HFJV resulted in mean PaO2 and PaCO2 values of 19.7 kPa and 6.1 kPa, respectively. No complications during HFJV were observed. In the test lung, combined HFJV applied with driving pressures of 0.7,1.0 bar and 0.9,1.2 bar for HF and LF jet ventilation, respectively, resulted in maximum peak and baseline distal airway pressures of 17.6 cm H2O and 5.4 cm H2O, respectively. Conclusion: The application of the combined double frequency HFJV was effective in maintaining gas exchange in the presence of laryngeal or tracheal stenoses. It provided good visibility of anatomical structures and offered space for surgical manipulation, avoiding the use of combustible material inside the larynx or trachea. [source] The Use of Cerebral Oximetry as a Monitor of the Adequacy of Cerebral Perfusion in a Patient Undergoing Shoulder Surgery in the Beach Chair PositionPAIN PRACTICE, Issue 4 2009Gregory W. Fischer MD Abstract Four cases of ischemic injury have been reported in patients undergoing orthopedic surgery in the upright position. We describe the use of cerebral oximetry as a monitor of the adequacy of cerebral perfusion in a 63-year-old woman who underwent arthroscopic rotator cuff surgery in a beach chair under general anesthesia. During positioning, a decrease in blood pressure was accompanied by a decrease in cerebral oxygen saturation (SctO2) and was treated with phenylephrine. When spontaneous ventilation resumed, an increase in end-tidal carbon dioxide was accompanied by an increase in SctO2. Cerebral oximetry may prove useful as a guide monitor and manage nonsupine patients. [source] Longtime performance and reliability of two different PtcCO2 and SpO2 sensors in neonatesPEDIATRIC ANESTHESIA, Issue 9 2008VERA BERNET Summary Objectives:, Blood gas monitoring is necessary in treatment of critically ill neonates. Whereas SaO2 can be estimated by pulse oximetry, PaCO2 is still most often assessed from blood samples. Aim:, To compare long time performance of an ear sensor for combined assessment of transcutaneous carbon dioxide (PtcCO2) and oxygen saturation (SpO2) (TOSCA Monitor; Radiometer, Switzerland) with a conventional PtcCO2 monitor (MicroGas 7650-500 rapid, Radiometer, Switzerland) in critically ill neonates. Methods:, Prospective, observational study. Twenty critically ill neonates were monitored for PtcCO2 and SpO2 using the Tosca and the MicroGas monitor for 24 h. TOSCA ear sensor was changed to the other ear lobe after 12 h and the MicroGas sensor four hourly on the trunk. Values obtained were compared with SaO2 and PaCO2 from arterial blood gas analysis using Bland,Altman analysis. Data are presented as median (range). Results:, Eighty-two paired measurements were obtained. Median age of the 20 patients was 4.5 days (1,26 days) and weight was 3.05 kg (0.98,3.95 kg). Bias and precision between PaCO2 and PtcCO2 were 0.14 and 1.45 kPa for the Tosca monitor and ,0.08 and 1.2 kPa for the MicroGas monitor, respectively. The two biases were significantly different (P = 0.0036). SpO2 assessment by TOSCA was comparable to SaO2 values (bias 0.26% and precision 4.14%). Conclusion:, The TOSCA monitor allows safe estimation of PtcCO2 and SaO2 in neonates. Measurements of PtcCO2 were less reliable with TOSCA compared with conventional monitoring but still allow assessing a trend of ventilation status in newborn patients. [source] A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patientsPEDIATRIC ANESTHESIA, Issue 6 2005TIA A. TORTORIELLO MD FAAP Summary Background :,Near-infrared spectroscopy (NIRS) is a noninvasive optical monitor of regional cerebral oxygen saturation (rSO2). The aim of this study was to validate the use of NIRS by cerebral oximetry in estimating invasively measured mixed venous oxygen saturation (SvO2) in pediatric postoperative cardiac surgery patients. Methods :,Twenty patients were enrolled following cardiac surgery with intraoperative placement of a pulmonary artery (PA) or superior vena cava (SVC) catheter. Five patients underwent complete biventricular repair , complete atrioventricular canal (n = 3) and other (n = 2). Fifteen patients with functional single ventricle underwent palliative procedures , bidirectional Glenn (n = 11) and Fontan (n = 4). Cerebral rSO2 was monitored via NIRS (INVOS 5100) during cardiac surgery and 6 h postoperatively. SvO2 was measured from blood samples obtained via an indwelling PA or SVC catheter and simultaneously correlated with rSO2 by NIRS at five time periods: in the operating room after weaning from cardiopulmonary bypass, after sternal closure, and in the CICU at 2, 4, and 6 h after admission. Results :,Each patient had five measurements (total = 100 comparisons). SvO2 obtained via an indwelling PA or SVC catheter for all patients correlated with rSO2 obtained via NIRS: Pearson's correlation coefficient of 0.67 (P < 0.0001) and linear regression of r2 = 0.45 (P < 0.0001). Separate linear regression of the complete biventricular repairs demonstrated an r = 0.71, r2 = 0.50 (P < 0.0001). Bland,Altman analysis showed a bias of +3.3% with a precision of 16.6% for rSO2 as a predictor of SvO2 for all patients. Cerebral rSO2 was a more accurate predictor of SvO2 in the biventricular repair patients (bias ,0.3, precision 11.8%), compared with the bidirectional Glenn and Fontan patients. Conclusions :,Regional cerebral oximetry via NIRS correlates with SvO2 obtained via invasive monitoring. However, the wide limits of agreement suggest that it may not be possible to predict absolute values of SvO2 for any given patient based solely on the noninvasive measurement of rSO2. Near-infrared spectroscopy, using the INVOS 5100 cerebral oximeter, could potentially be used to indicate trends in SVO2, but more studies needs to be performed under varying clinical conditions. [source] Hemoglobin lansing: A novel hemoglobin variant causing falsely decreased oxygen saturation by pulse oximetry,AMERICAN JOURNAL OF HEMATOLOGY, Issue 8 2009Kiran V. Sarikonda No abstract is available for this article. [source] Clinic and radiological improvement of lipoid pneumonia with multiple bronchoalveolar lavagesPEDIATRIC PULMONOLOGY, Issue 4 2009Selma M.A. Sias MD Abstract Objective To assess the potential role of multiple bronchoalveolar lavages (BALs) in the treatment of children with lipoid pneumonia (LP). Materials and Methods This prospective study included 10 children (7 female, 3 male) with LP secondary to mineral oil aspiration. The age ranged from 3 months to 7 years and 1,60 days history of mineral oil intake, with a 6 months clinic follow-up. High-resolution computer tomography (CT) was performed 1,7 days prior to treatment and 2,20 days after the last therapeutic BAL, and reviewed by two experienced chest radiologists. Oxygen saturation was measured with digital oximetry. Therapeutic BAL was performed weekly until BAL fluid was nearly transparent and the cell count returned to normal range values. Results In all children, the initial CT scans showed multifocal bilateral consolidation involving mainly the dorsal and central regions. The areas of consolidation had foci of decreased attenuation in eight patients. Following a total of 4,10 therapeutic BALs, the CT scans returned to normal in 3 patients, improved considerably in 5, and showed only slight improvement in 2. Oxygen saturation increased from 88.8,±,3.4% at presentation to 96.2,±,0.8% after treatment (P,<,0.0001). Multiple lavages reduced (P,<,0.003) numbers of lipid-laden macrophages and restored BAL cellularity to normal range values. Conclusion Multiple therapeutic BAL of children with LP results in significant improvement of CT findings, oxygen saturation, restoration of BAL fluid cellularity and clinical recover without any evidence of respiratory distress at the end of treatment and 6 months after the last BAL. Pediatr Pulmonol. 2009; 44:309,315. © 2009 Wiley-Liss, Inc. [source] Cerebral oximetry improves detection of sickle cell patients at risk for nocturnal cerebral hypoxia,PEDIATRIC PULMONOLOGY, Issue 11 2006Ashok B. Raj MD Abstract We previously used cerebral oximetry to identify low cerebral venous oxygen saturation in waking children with sickle cell disease (SCD). Because arterial oxyhemoglobin desaturation is common during sleep in SCD patients, this study compared both waking and sleeping systemic arterial and cerebral venous oxygenation dynamics in children with and without SCD. Seventeen African-American (AA) children with homozygous SCD [8 (4,15) years; 29% male; normal transcranial Doppler velocities] were compared with a control cohort (CON) comprised of six healthy AA children [9 (4,16) years, 33% male]. Standard all-night polysomnographic recordings were performed, including measurement of arterial oxygen saturation by pulse oximetry (SpO2). Regional cerebral oxygen saturation (rSO2) was measured non-invasively with cerebral oximetry. Intra-cohort comparisons examined the influence of sleep on SpO2 and rSO2 in the subjects. Inter-cohort comparisons of SpO2, rSO2, and the rSO2/SpO2 ratio assessed the impact of SCD on systemic and cerebral oxygenation during wakefulness and sleep. Cohort differences in SpO2 were not statistically significant in either wakefulness or sleep. However, only in the SCD cohort was the magnitude of SpO2 change statistically significant (P,=,0.002). In contrast, both waking and sleep rSO2 cohort median values did differ significantly [awake: CON 76 (67,86) vs. SCD 62 (58,71), P,=,0.01; sleep: CON 65 (60,77) vs. SCD 55 (48,61), P,=,0.01)]. The waking rSO2/SpO2 ratio was also significantly lower in the SCD group [CON 0.78 (0.68,0.88) vs. SCD of 0.66 (0.61,0.72); P,=,0.015]. During sleep, the ratio was also significantly lower in the SCD group [CON 0.71 (0.66,0.81) vs. SCD 0.59 (0.52,0.65); P,=,0.011]. Our findings suggest that SCD patients may be at increased risk of cerebral hypoxia during both wakefulness and sleep. Pediatr Pulmonol. 2006, 41:1088,1094. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||