Masks, math, and midazolam: Emergency paediatric sedation monitoring Q&A

Internationally, sedation of paediatric patients for short procedures is becoming a common treatment option in a variety of areas outside of the operating theatre. However, there are controversies about sedation/pain management and appropriate monitoring, especially in Emergency Department environments. What needs to be monitored, how often, and why? This article will, from the perspectives of emergency and anaesthesia professionals, review the research detailing what emergency department nurses really want and need to know.     

A prototype device for standardized calibration of pulse oximeters

Objective.To develop and test a method for standardized calibrationof pulse oximeters. Methods.A novel pulse oximeter calibrationtechnique capable of simulating the behavior of real patients is discussed.It is based on an artificial finger with a variable spectral-resolved lightattenuator in conjunction with an extensive clinical database of time-resolvedoptical transmission spectra of patients fingers in the wavelength range600–1000 nm. The arterial oxygen saturation of the patients at the timeof recording was derived by analyzing a corresponding blood sample with aCO-oximeter. These spectra are used to compute the modulation of the lightattenuator which is attached to the artificial finger. This calibration methodwas tested by arbitrarily playing back recorded spectra to pulse oximeters andcomparing their display to the value they displayed when the spectra wererecorded. Results.We were able to demonstrate that the calibratorcould generate physiological signals which are accepted by a pulse oximeter.We also present some experience of playing back recorded patient spectra. Themean difference between the original reading of the pulse oximeters and thedisplay when attached to the calibrator is 1.2 saturation points (displayedoxygen saturation SpO₂) with a standard deviation of 1.9 saturationpoints. Conclusions.The tests have shown the capabilities of aspectral light modulator for use as a possible calibration standard for pulseoximeters. If some improvements of the current prototype can be achieved weconclude from the experience with the device that this novel concept for thecalibration of pulse oximeters is feasible and that it could become animportant tool for assessing the performance of pulse oximeters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pulse oximetry for hypoxemia: a warning to users and manufacturers

Pulse oximetry represents a major advance in patient monitoring, but measurement below 70 to 80% saturation has important limitations. Several authors have tested pulse oximetry at low saturations with conflicting results. A review of these data indicates that every patient with a pulse oximeter value below 75 to 80% SaO₂ should have one or more invasive measurements of the arterial SaO₂ in order to avoid undetected severe hypoxemia.     

Evaluation of a pulse oximeter during profound hypothermia. An assessment of the Biox 3700 during induction of hypothermia before cardiac surgery in paediatric patients

The accuracy of the Ohmeda Biox 3700 pulse oximeter was evaluated in 10 paediatric patients, deliberately surface cooled to 25°C in preparation for cardiac surgery, by comparing the arterial oxygen saturation results obtained from an Ohmeda Biox 3700 and a Radiometer OSM-2 Hemoximeter. Though, there was a good correlation between the two series of results, the arterial oxygen saturation was over-estimated by the pulse oximeter compared to the OSM-2 Hemoximeter in the temperature range 36° to 30°C and under-estimated below 30°C. These differences were greatest when the initial saturations were low.     

A prototype device for standardized calibration of pulse oximeters II

Objective.There is no commonly accepted in vivocalibration method for pulse oximeters available up to now. On the basis of a prototype device for the calibration of pulse oximeters which was introduced recently, a second approach based on the same concept was tackled in order to design a reliable method for standardized calibration of pulse oximeters. Methods.An extensive clinical database of time-resolved optical transmission spectra of patient fingers is used to simulate the behavior of patients. A device which is capable of playing back these spectroscopic data to pulse oximeters, and a database where the oxygen status measured with the reference method (Co-Oximetry) is stored, are the main parts of the concept. The playback device has an artificial finger as interface to the pulse oximeters and serves to collect light from the pulse oximeter for analysis and to playback simulated light to the pulse oximeter. The light intensity emitted by two LEDs which illuminates the pulse oximeter detector is controlled via a computer in such a way that it is the same as if the pulse oximeter light had passed the finger. The pulse oximeter display during the data playback can thus be compared to the true SaO₂ of the patient. The device is tested with 4 pulse oximeters based on 100 patient spectra. Results.For the four pulse oximeters used in this investigation, an Agilent Technologies CMS monitor (formerly Hewlett-Packard), an Ivy 2000 with Masimo Set^TM technology and Nellcor N-3000 and N-395, there is good correlation between SpO₂ and SaO₂, and mean and standard deviation of in vivoSpO₂-SaO₂ and playback SpO₂-SaO₂ are in good agreement. For two instruments, Nellcor N3000 and Agilent CMS Monitor, a quantitative comparison between the in vivoand in vitroSpO₂ results was derived. A mean of the deviation playback vs. in vivoSpO₂ is less than 0.5% SpO₂. The error limits are comparable with the calibration error of the conventional calibration routine. The device is also capable of data playback even in situations with rapid desaturation changes, as displayed in Figure 2. For the other tested pulse oximeters the results are comparable. Conclusions.Compared to the first prototype the current version is simpler and less expensive in production. Many of previously existing problems are solved and the applicability to a large variety of pulse oximeters and sensors is given. The novel concept for the calibration of pulse oximeters is a tool for assessing the performance of pulse oximeters.     

Preprocedural Considerations in Gastrointestinal Endoscopy

The current practice of open-access endoscopy allows primary care and other non-gastroenterology physicians to directly refer patients for routine gastrointestinal endoscopic procedures. Open-access endoscopy is considered to be more cost-effective and time efficient than the traditional practice of referring patients for preprocedural consultation with a gastrointestinal endoscopist. Several studies have evaluated the performance of endoscopic procedures in an open-access environment and the utility of structured referral mechanisms to ensure safe and appropriately indicated procedures. This review focuses on 4 common preprocedural issues in gastrointestinal endoscopy encountered by primary care physicians: management of anticoagulation and antiplatelet therapy, indication for prophylactic antibiotic drug therapy, need for anesthesia-assisted sedation, and management of poor bowel preparation. We summarize the current guidelines that address these 4 common preprocedural issues to facilitate safe and clinically appropriate procedures in open-access endoscopy.     

Feasibility of pulse oximetry in the initial prehospital management of victims of drowning: a preliminary study

Aim

Immediate delivery of oxygen is the most important treatment for victims of drowning at the rescue site. Monitoring oxygen saturation with pulse oximetry is potentially useful, but its use may be limited by poor peripheral perfusion due to hypothermia. This preliminary study explores the feasibility of pulse oximetry in simulated minor drowning scenarios.

Materials and methods

Six different pulse oximeters were tested on ten healthy volunteers after brief submersion, after ten minutes of swimming in a swimming pool (warm water, temperature 21 °C), and in the sea (cold water, temperature 16 °C). A measured oxygen saturation reading ≤94% was assumed to be incorrect.

Results

There was considerable variability between each pulse oximeter. In warm water, 5.8% of measurements were outside the predicted range (8.3% after submersion, 3.3% after swimming), compared to 34% in cold water (20% after submersion, 48% after swimming). The spurious measurements came from two pulse oximeters in warm water, but from all six in cold water. The best and worst performing pulse oximeters showed 5% and 33% measurements respectively outside the predicted range.

Conclusion

The performance of pulse oximeters varies considerably in healthy volunteers submersed or immersed in warm or cold water. Further studies are needed to understand these differences.     

NADH-diaphorase deficiency identified in a patient with congenital methaemoglobinaemia detected by pulse oximetry

We report on a young woman with congenital methaemoglobinaemia detected by a pulse oximeter during anaesthesia. Investigation of the patient and her family showed that the methaemoglobinaemia resulted from a recessive deficiency of NADH-diaphorase enzyme. A knowledge of the working principles and limitations of pulse oximetry is essential to determine appropriaie management in desaturation episodes during the perioperative period. Received: 17 December 1997 Accepted: 12 February 1998     

Risk Management for Gastrointestinal Endoscopy in Elderly Patients: Questionnaire for Patients Undergoing Gastrointestinal Endoscopy

More elderly patients now undergo gastrointestinal endoscopy following recent advances in endoscopic techniques. In this study, we conducted a high-risk survey of endoscopies in Japan, using a questionnaire administered prior to upper gastrointestinal tract endoscopy (UGITE), and identified anticholinergic agents and glucagon preparations as high-risk premedication. We also evaluated the cardiovascular effects of anticholinergic agents and glucagon through measurements of plasma levels of human atrial natriuretic peptide (hANP) and human brain natriuretic peptide (hBNP). The subjects were 1480 patients who underwent UGITE. Nurses administered a pre-endoscopy questionnaire, questioning subjects regarding heart disease, hypertension, glaucoma, and urinary difficulties as risk factors for anticholinergic agents, and Diabetes mellitus as a risk factor for glucagon preparations. Evaluation of subjects divided into under 65 and over 65 age groups revealed that in subjects aged 65 and over, risk factors for anticholinergic agents were significantly more high than those for glucagon. Analysis of the cardiovascular effects of anticholinergic agents and glucagon, in the elderly patients showed that hANP levels were significantly higher following administration of anticholinergic agents, but the change was not significant for glucagon premedication. Taking a detailed history before UGITE with the aid of a questionnaire at the same time as informed consent is obtained, is extremely useful in terms of risk management and selection of the appropriate premedication.     

The accuracy of the biox 3700 pulse oximeter in patients receiving vasoactive therapy

The accuracy of pulse oximetry for the prediction of oxygen saturation of arterial blood in patients with shock has been hardly studied. This study was undertaken to determine if O₂ arterial saturation estimated by the Biox 3700 pulse oximeter (SpO₂) with an ear probe could reliably substitute for the measurements of O₂ saturation (HbO₂) with an IL-282 Co-Oximeter in samples of arterial blood obtained from 24 caucasian patients. All patients were mechanically ventilated and needed vasoactive drugs (dopamine and/or dobutamine). Of 24 patients 13 had shock: cardiogenic (n=6) and septic (n=7). The mean difference between HbO₂ and SpO₂ was 2.49%±4.24, with a 95% confidence interval of 0.7% to 4.3% (p=0.009). There were clinically important differences between both methods since in 9 of 24 patients (37%) SpO₂ values were at least 4% lower or greater than HbO₂. This disagreement was also apparent in patients with (6/13, 46%) or without shock (3/11, 27%). To conclude, pulse oximetry is not always a sufficiently reliable method to predict HbO₂ in patients with or without shock treated with vasoactive drugs.     

107例小儿消化道出血胃镜检查结果分析

目的：了解不同年龄组消化道出血的病因和合理的胃镜检查时间。方法：对107例临床疑似上消化道出血的患儿进行纤维胃镜检查。结果：确诊为上消化道出血的79例（十二指肠溃疡61例,胃溃疡7例,食道静脉曲张3例,食管炎1例,贲门粘膜撕裂症3例,十二指肠憩室2例,脑疝2例）,小肠出血6例（3例小肠憩室、2例克隆氏病,1例小肠结核） ,咽血综合症3例,未检查出病因19例。结论：十二指肠球部溃疡、胃溃疡是年龄较大儿童消化道出血最常见的原因,先天性消化道畸形是婴幼儿消化道出血的另一个重要原因,患儿在出血48h内纤维胃镜检查阳性率最高,小儿上消化道出血急症胃镜检查是一种快速、准确、较安全的检查方法。     

脉搏氧饱和度测定法在PICU的临床应用评价

目的　了解脉搏氧饱和度测定法在监测儿科危重病例时的准确性和可靠性。方法　在抽取动脉血作血气分析的同时 ,读取两种脉搏氧饱和度仪显示的SpO2 值。采用配对计量资料比较的t检验、直线相关分析和四格表资料的 χ2 检验比较脉膊氧饱和度和血氧饱和度。结果　在各种病理状态和各个年龄组 ,当PaO2 在 45～ 10 0mmHg范围内 ,两种仪器测定的SpO2 与SaO2 之间的差异均无显著性意义 (P值均 >0 .0 5 ) ,且SpO2 与SaO2 呈非常显著正相关 (P值均 <0 .0 1) ,并能较准确地预测PaO2 。但当PaO2 <45mmHg或 >10 0mmHg时 ,SpO2 不能准确预测PaO2 。结论　在一定范围内 ,脉搏氧饱和度仪能准确测定危重患儿机体氧合状态。但在临床应用时 ,必须结合病情观察及血气分析 ,才能对患儿心肺功能状态作出更精确的评估     

上消化道出血的早期内镜检查与治疗359例分析

目的：探讨早期内镜对上消化道出血患者的影响，评价早期内镜利弊。方法：对住院的359例上消化道出血患者进行早期内镜及非早期内镜对比分析，评价早期内镜检查及镜下治疗与再出血、住院时间的关系。结果：49．86％的患者完成了早期内镜检查，早期内镜比非早期内镜平均住院时间短。对有高度再出血危险的患者，早期内镜及内镜下治疗可控制出血、降低再出血。结论：上消化道出血患者早期常规应用内镜和选择性内镜下治疗可降低再出血、住院时间。     

心脏病患者围术期脉搏血氧饱和度下降的护理观察及处理

应用脉搏血氧饱和度（SpO2）监测仪持续无创监测,能连续动态地反映机体氧合状况,及时发现心脏病患者围术期早期低氧血症,为抢救和护理提供依据。SpO2监测是将探头指套固定在患者指端甲床,利用手指作为盛装血红蛋白的透明容器,测定通过组织床的光传导强度,来计算血氧饱和度。SpO2读数可反映患者的呼吸功能,并在一定程度上反映动脉血氧的变化,可为临床早期发现低氧血症提供有价值的信息。现将心脏病患者围术期脉搏血氧饱和度下降的的观察体会介绍如下。     

A novel technique to intubate patients without reliable pulse oximetry

Although advances have been made in the approach to airway management, intubating critically ill patients in the Emergency Department (ED) can still be perilous. In some cases, poor peripheral perfusion may preclude obtaining a consistent or reliable pulse oximetry waveform, and the intubator will not accurately know when the patient begins to desaturate. We describe a case of a patient requiring intubation in whom we were unable to obtain a consistent pulse oximetry waveform. We utilized a novel technique in which a Biphasic Cuirass Ventilation (BCV) device was applied to maintain oxygenation and ventilation during the performance of rapid sequence intubation (RSI). This technique has the potential to improve the safety of RSI, especially in the critically ill patient.