Determination of blood volume by pulse CO-oximetry

The objective of this study was to determine whether changes in carboxyhaemoglobin (COHb) saturation following carbon monoxide (CO) rebreathing can be accurately detected by pulse CO-oximetry in order to determine blood volume. Noninvasive measurements of carboxyhaemoglobin saturation (SpCO) were continuously monitored by pulse CO-oximetry before, during and following 2 min of CO rebreathing. Reproducibility and accuracy of noninvasive blood volume measurements were determined in 16 healthy non-smoking individuals (15 males, age: 28 ± 2 years, body mass index: 25.4 ± 0.6 kg m(-2)) through comparison with blood volume measurements calculated from invasive measurements of COHb saturation. The coefficient of variation for noninvasive blood volume measurements performed on separate days was 15.1% which decreases to 9.1% when measurements were performed on the same day. Changes in COHb saturation and SpCO following CO rebreathing were strongly correlated (r = 0.90, p < 0.01), resulting in a significant correlation between invasive and noninvasive blood volume measurements (r = 0.83, p = 0.02). Changes in SpCO following CO rebreathing can be accurately detected by pulse CO-oximetry, which could potentially provide a simplified, convenient and reproducible method to rapidly determine blood volume in healthy individuals.     

Evaluation of noninvasive hemoglobin monitoring for hematological disorders

The Astrim is a noninvasive hemoglobin monitoring device that uses near-infrared radiation. We studied the usefulness of this device for patients with hematological disorders. We measured hemoglobin levels 309 times in 140 subjects, using an automated hematology analyzer (K-4500) and the Astrim. The coefficient of correlation between Hb levels with the K-4500 (K-Hb) and the Astrim (A-Hb) was r = 0.591 (P < 0.001). The coefficient of correlation between A-Hb and K-Hb from 174 specimens with anemia and 135 without anemia was r = 0.531 (P < 0.001) and r = 0.345 (P < 0.001), respectively. In the 309 specimens, the Astrim showed a diagnostic sensitivity and specificity for anemia of 78.3% and 69.0%, respectively. While the r-values, sensitivity, and specificity were passable, they appeared to be insufficient for an accurate evaluation. We believe this was caused by the measurement conditions (i.e., the finger selected for measurement, the finger position in relation to the CCD camera, and the finger temperature). On the other hand, the precision test results were good. Therefore, if careful attention is paid to measurement conditions, the noninvasive Astrim is clinically useful for continuous hemoglobin monitoring of hematological disorders and patients with hemorrhagic diseases, such as perioperative hemorrhage and gastrointestinal bleeding. However, it is difficult to determine Hb concentrations in one measurement using the Astrim because the r-values, sensitivity, and specificity are insufficient for accurate evaluations of in-patients, particularly patients with advanced diseases. Therefore, we believe it is necessary to improve the system so that A-Hb can be accurately determined in one measurement.     

Noninvasive pulse CO-oximetry expedites evaluation and management of patients with carbon monoxide poisoning

Purposes

Pulse CO-oximetry (Rad-57; Masimo Corp, Irvine, CA) has been available since 2005. To date, all published clinical studies have focused on clinical reliability and whether the device enhances case finding through screening of various populations. This study examines whether use of pulse CO-oximetry shortens the time to diagnosis and treatment of patients with carbon monoxide (CO) poisoning.

Basic Procedures

Data from the joint Undersea and Hyperbaric Medical Society/Centers for Disease Control and Prevention CO poisoning surveillance system from August 2008 to July 2011 were analyzed. Of 1711 cases of CO poisoning treated with hyperbaric oxygen in the United States and reported through the system, 1606 had their initial carboxyhemoglobin (COHb) level measured by laboratory CO-oximetry and 105 by pulse CO-oximetry. Patients were selected from the laboratory CO-oximetry group to match each of the 105 patients evaluated by pulse CO-oximetry in 5 characteristics—age, sex, race/ethnicity, intent of poisoning, and occurrence of loss of consciousness. Measures of timeliness in measurement and management were compared between the 2 groups.

Main Findings

Patients with initial COHb measurement by pulse CO-oximetry had significantly shorter time to measurement of COHb, higher average levels of COHb, and shorter time from the end of CO exposure to the initiation of hyperbaric oxygen treatment. On average, patients evaluated by pulse CO-oximetry reached the hyperbaric chamber 1 hour faster than did patients evaluated by laboratory CO-oximetry (P < .01).

Principle Conclusions

Pulse CO-oximetry is associated with more rapid diagnosis and initiation of hyperbaric oxygen therapy in CO-poisoned patients compared with laboratory CO-oximetry. The impact on clinical outcome remains to be determined.     

Accuracy of non-invasive continuous total hemoglobin measurement by Pulse CO-Oximetry in severe traumatized and surgical bleeding patients

The Masimo Radical-7 Pulse CO-Oximeter (Masimo Corp., USA) non-invasively computes hemoglobin concentration (SpHb). SpHb was compared to Co-Oximeter readings (CoOxHb) of arterial samples in surgery patients of the emergency department. Forty-six patients were enrolled. The Masimo R1 25L (revision F and G) adult adhesive sensor was attached to the ring finger of the arterially cannulated hand. Before start, every 30 min during surgery and in the case of severe bleeding SpHb and CoOxHb values were documented. SpHb and post hoc adjusted SpHb (AdSpHb) values were analyzed. Linear regression analysis and Bland–Altman plot for agreement were performed. The detection failure rate of SpHb was 24.5 %. CoOxHb and SpHb showed a strong correlation (r = +0.81), but agreement was moderate [bias (LOA) of ?0.6 (?3.0; +1.9)] g/dl. Positive and negative predicted value was 0.49 and 0.69. Exclusion of changes of CoOxHb values ≤1 g/dl resulted in a positive and negative predictive value of 0.66 and 1.00. Post hoc adjustment of the SpHb (AdSpHb) improved linear correlation of CoOxHb and AdSpHb [r = +0.90 (p < 0.001)] but less the agreement [bias (LOA) of CoOxHb and AdSpHb = ?0.1 (?2.1/+1.9) g/dl]. SpHb agreed only moderately with CoOxHb values and predicted decreases of CoOxHb only if changes of SpHb ≤ 1.0 g/dl were excluded. The detection failure rate of SpHb was high. At present, additional refinements of the current technology are necessary to further improve performance of non-invasive hemoglobin measurement in the clinical setting.     

Validation of a noninvasive blood pressure monitoring device in normotensive and hypertensive pediatric intensive care patients

Objective. To evaluate the performance and to define limitations of a noninvasive blood pressure monitoring device in the critically ill pediatric population. Method. Patients were included in the study if they were admitted to the Pediatric Intensive Care Unit, were between the ages of 1 month and 18 years with wrist circumferences of ≥ 10 cm, and had an indwelling arterial line. Patients were excluded if their systolic blood pressure differed by ≥ 7.5% between their upper extremities. The measurements were collected simultaneously with those from an arterial line by a computer interfaced with the noninvasive blood pressure monitoring system and the patient’s monitor. Heart rates were calculated from the recorded pulse waveforms of the arterial lines. Comparison analyses were performed via bias and precision plots of the blood pressure and heart rate data in addition to calculation of Pearson’s correlation coefficients and concordance correlation coefficients. As a nonparametric method of comparison, the proportion of measurements that differed by greater than 10% was calculated. Results. Blood pressures and heart rates of 20 patients between the ages of 12 months and 17 years were monitored by a noninvasive blood pressure monitor for 30 min per patient. This data collection resulted in 2015 data points for each blood pressure and heart rate for comparison of methods. Concordance correlation coefficients were the following: systolic blood pressure, 0.93; diastolic blood pressure, 0.93; mean blood pressure, 0.94; and heart rate, 0.85. Conclusions. The noninvasive blood pressure monitor is capable of producing an accurate blood pressure measurement every 12–15 heartbeats in addition to providing a pulse waveform and digital display of the heart rate. Our study showed good agreement between the methods in the normotensive and hypertensive critically ill pediatric population with a wrist circumference limitation defined at ≥ 11 cm. Study performed at Arkansas Children’s Hospital, Little Rock, AR, USA. Information presented at 2002 Biomedical Engineering Society Annual Fall Meeting, Houston, TX, October 26, 2002. Wankum PC, Thurman TL, Holt SJ, Hall RA, Simpson PM, Heulitt MJ. Validation of a noninvasive blood pressure monitoring device in normotensive and hypertensive pediatric intensive care patients.     

Effects of indigo carmine intravenous injection on noninvasive and continuous total hemoglobin measurement

The effects of an intravenous injection of indigo carmine on noninvasive and continuous total hemoglobin (SpHb) measurement were retrospectively evaluated. The subjects were 21 patients who underwent elective gynecologic surgery under general anesthesia. During surgery, 5 mL of 0.4 % indigo carmine was intravenously injected, and subsequent changes in SpHb concentrations were evaluated. The results demonstrate that the pre-injection SpHb level was 10 g/dL, and the minimum post-injection SpHb level was 8.3 g/dL. The amount of decrease was 1.8 g/dL. The time to reach the minimum value was 4 min, and the time to return to the pre-injection value was 15 min. The decrease in SpHb was greater in the group with a perfusion index (PI) < 1.4 than in the group with a PI > 1.4. The assessment of SpHb after an intravenous injection of indigo carmine necessitates caution.     

Validation of noninvasive pulse contour cardiac output using finger arterial pressure in cardiac surgery patients requiring fluid therapy

Introduction

Nexfin (Edwards Lifesciences, Irvine, CA) allows for noninvasive continuous monitoring of blood pressure (ABP_NI) and cardiac output (CO_NI) by measuring finger arterial pressure (FAP). To evaluate the accuracy of FAP in measuring ABP_NI and CO_NI as well as the adequacy of detecting changes in ABP and CO, we compared FAP to intra-arterially measured blood pressure (ABP_IA) and transpulmonary thermodilution (CO_TD) in postcardiac surgery patients during a fluid challenge (FC).

Methods

Twenty sedated patients post cardiac surgery were included, and 28 FCs were performed. Measurements of ABP and CO were simultaneously collected before and after an FC, and we compared CO and blood pressure.

Results

Finger arterial pressure was obtainable in all patients. When comparing ABP_NI with ABP_IA, bias was 2.7 mm Hg (limits of agreement [LOA], ± 22.2), 4.9 mm Hg (LOA, ± 13.6), and 4.2 mm Hg (LOA, ± 13.7) for systolic, diastolic, and mean arterial pressure, respectively. Concordance between changes in ABP_NI and ABP_IA was 100%. Mean bias between CO_NI and CO_TD was − 0.26 (LOA, ± 2.2), with a percentage error of 38.9%. Concordance between changes in CO_NI vs CO_TD and was 100%.

Conclusion

Finger arterial pressure reliably measures ABP and adequately tracks changes in ABP. Although CO_NI is not interchangeable with CO_TD, it follows changes in CO closely.     

Capnometry for noninvasive continuous monitoring of metabolic status in pediatric diabetic ketoacidosis

OBJECTIVE: To determine the utility of continuous noninvasive capnometry for monitoring pediatric patients with diabetic ketoacidosis as assessed by the agreement between end-tidal carbon dioxide (PetCO2) and PCO2 DESIGN: Clinical, prospective, observational study. SETTING: University affiliated children's hospital. INTERVENTIONS: Patients with diabetic ketoacidosis were monitored with an oral/nasal carbon dioxide (CO2) sampling cannula while in the emergency department. Laboratory studies were ordered per protocol. PetCO2 values were correlated with respiratory rate, PCO2, and pH. MEASUREMENTS AND MAIN RESULTS: One hundred twenty-one patients were monitored for 5.9 +/- 0.32 hrs. The average (mean +/- sd) initial values for pH were 7.08 +/- 0.18; respiratory rate, 35.1 +/- 9.1 breaths/min; PetCO2, 18.6 +/- 10.8 torr; and venous PCO2, 20.2 +/- 10.6 torr. At the conclusion of the observation period, averages were pH, 7.29 +/- 0.05; respiratory rate, 22.4 +/- 3.7 breaths/min; PetCO2, 35.3 +/- 5.8 torr; and venous PCO2, 36.8 +/- 5.3 torr. For all 592 observations, the correlations between PetCO2 and venous PCO2 (r =.92, p =.0001), PetCO2 and pH (r =.88, p =.0001), Petco2 and respiratory rate (r = -.79, p =.0001), and respiratory rate and pH (r = -.80, p =.0001) were statistically significant and the correlations with respiratory rate were inversely related to pH and PetCO2. The difference scores were not related to the average scores for initial readings (r = -.073, p =.43), final readings (r = -.124, p =.18), and overall readings (r =.057, p =.17). Limits of agreement between the two methods were established with PetCO2 lower than venous PCO2 with 95% limits of agreement 0.8 +/- 8.3 (2 sd) torr. CONCLUSIONS: PetCO2 monitoring of patients with diabetic ketoacidosis provides an accurate estimate of PCO2. Noninvasive PetCO2 sampling may be useful in patients with diabetic ketoacidosis to allow for continuous monitoring of patients.     

12例肺移植围术期患者应用脉搏指示连续心排血量监测的护理配合

报告了12例肺移植围术期患者应用脉搏指示连续心排血量监测(PICCO)的护理。在肺移植患者围术期,观察胸腔内血液容积指数(ITBI)、血管外肺水指数(ELWI)、脉搏轮廓心输出量(PCCO)、每搏量指数(SVI)、全心舒张末期容积指数(GEDI)、肺血管通透性指数(PVPI)等指标,分析肺移植术后肺再灌注损伤情况,防治患者肺水肿。本组术后1d拔管10例,2d拔管2例。其中2例因并发症分别于术后40d和9个月死亡,其余目前存活。PICCO技术可充分评估肺移植围手术期血流动力学变化,对指导肺移植术后的液体管理有积极作用。技术准入管理、详细掌握患者病情、规范操作方法、细致护理观察、及时处理并发症等是应用PICCO成功的保证。     

Comparison of the accuracy of noninvasive hemoglobin monitoring for preoperative evaluation between adult and pediatric patients: a retrospective study

We measured noninvasive hemoglobin (SpHb) levels during the pre-anesthesia visit in patients planning elective surgery. Differences between SpHb and laboratory-measured hemoglobin (Hb_lab) were compared between adult and pediatric patients. In the pre-anesthesia visiting office, we routinely monitor noninvasive Hb levels with oxygen saturation and heart rate using Masimo Radical-7® Pulse CO-Oximetry (Masimo Corp., Irvine, CA, USA). We attached the R1 20 (body weight, 10–50 kg) or R1 25 (body weight?>?30 kg) probe on the index finger. After signal stabilization, SpHb and perfusion index (PI) were recorded. We retrospectively reviewed the recorded data and included patients who visited the anesthesiologist within 24 h after venous sampling. Bias was calculated by subtracting Hb_lab from SpHb. We compared the biases of adult and pediatric patients (<?18 years) and evaluated correlation coefficients between the bias and Hb_lab. Records of 105 patients were reviewed and 100 data points of 50 patients in each group were analyzed. The median?±?interquartile range bias was ??2.6?±?2.2 and ??1.2?±?1.5 g/dL in adult and pediatric patients, respectively (P?<?0.001); the corresponding mean?±?standard deviation PIs were 4.4?±?3.1 and 5.9?±?2.7, respectively (P?=?0.19). Bias was inversely proportional to Hb_lab irrespective of age. The correlation coefficient between the bias and Hb_lab was ??0.81 in adults and ??0.54 in pediatric patients (P?<?0.001). SpHb and Hb_lab measured during pre-anesthesia visits showed a smaller difference in pediatric than in adult patients. Lower Hb_lab corresponded to higher accuracy.     

Clinical evaluation of continuous noninvasive blood pressure monitoring: Accuracy and tracking capabilities

A continuous, noninvasive device for blood pressure measurement using pulse transit time has been recently introduced. We compared blood pressure measurements determined using this device with simultaneous invasive blood pressure measurements in 35 patients undergoing general endotracheal anesthesia. Data were analyzed for accuracy and tracking ability of the noninvasive technique, and for frequency of unavailable pressure measurements by each method. A total of 25, 133 measurements of systolic pressure, diastolic pressure, and mean arterial pressure (MAP) by each method were collected for comparison from 35 patients. Accuracy was expressed by reporting mean bias (invasive pressure minus noninvasive pressure) and limits of agreement between the two measurements. After correction for the offset found when measuring invasive and oscillometric methods of arterial pressure measurement, the mean biases for systolic, diastolic, and mean pressures by the pulse wave method were ?0.37 mm Hg, ?0.01 mm Hg, and ?0.05 mm Hg, respectively (p<0.001). The limits of agreement were: ?29.0 to 28.2 mm Hg, ?14.9 to 14.8 mm Hg, and ?19.1 to 19.0 mm Hg, respectively (95% confidence intervals). When blood pressure measured invasively changed over time by more than 10 mm Hg, the noninvasive technique accurately tracked the direction of change 67% of the time. During the entire study, 3.2% of the invasive measurements were unavailable and 12.9% of the noninvasive measurements were unavailable. The continuous noninvasive monitoring technique is not of sufficient accuracy to replace direct invasive measurement of arterial blood pressure, owing to relatively wide limits of agreement between the two methods. The continuous noninvasive method may serve as an intermediate technology between intermittent noninvasive and continuous invasive measurement of blood pressure if tracking capabilities can be improved; but, further refinement is needed before it can be recommended for routine intraoperative use.     

心肺联合超声与PICCO对急危重症患者监测结果的相关性

目的分析心肺联合超声与脉搏指数连续心输出量（PICCO）对急危重症患者监测结果的相关性。 方法采用前瞻性自身对照研究方法,选取2020年4至6月入住上海市第十人民医院急诊ICU的患者,采用PICCO监测患者心输出量（CO）和血管外肺水指数（ELWI）,同时使用心肺联合超声监测患者CO、左心室流出道（LVOT）血流的速度时间积分（VTI）和肺部超声B线情况,分析两种方法监测结果的相关性。 结果共入选41例患者,其中男∶女为26∶15,年龄（73.6±8.85）岁。超声和PICCO两种方法下监测的CO值结果比较,差异无统计学意义［（4.87±1.04）L/min vs （5.11±1.05）L/min,t=1.01,P=0.316］,Pearson相关性分析提示两者之间存在显著相关性（r=0.911,95%CI：0.82~0.96,P＜0.001）;肺部超声B线与ELWI存在显著相关性（r=0.770,95%CI：0.58~0.88,P＜0.001）。 结论心肺联合超声监测急危重症患者与PICCO监测结果存在相关性。     

无创性监测方法对间质性肺疾病患者的预后性评估

间质性肺疾病(ILD)是一类以炎症和纤维化为特征的异质性疾病,其中特发性肺间质纤维化(IPF)和结缔组织相关性间质性肺疾病(CTD-ILD)是常见的两种肺疾病.对于IPF和CTD-ILD诊断后,需纳入慢病管理,评估疾病临床进展及预后,及时采取干预措施.     

脉搏指数连续心排血量监测指标与脓毒性休克患者预后的相关性分析

目的探讨脉搏指数连续心排血量（PiCCO）监测指标与脓毒性休克患者预后的相关性。方法根据预后情况将43例脓毒性休克患者分为死亡组与存活组,比较2组患者的一般资料、治疗前APACHEⅡ评分、PiCCO监测指标,并将具有统计学差异的PiCCO监测指标与死亡率进行相关性分析。结果 43例患者中存活21例（48.8%）,死亡22例（51.2%）,死亡组与存活组患者在性别、年龄、感染部位、MAP、CVP、ITBVI、SVRI等方面比较差异均无统计学意义（P〉0.05）,而在治疗前APACHEⅡ评分、CI、EVLWI及PVPI方面比较存在显著差异（P〈0.01）;CI与患者死亡率呈显著负相关（r=-0.18,P〈0.01）,EVLWI、PVPI均与患者死亡率呈显著正相关（r=0.31,P〈0.01;r=0.19,P〈0.01）。结论 PiCCO仅通过中心静脉及动脉导管即可精确、持续地监测多项指标,创伤小,危险性低,其中CI、PVPI、EVLWI等指标与脓毒性休克患者预后具有密切相关性,对于指导治疗及评估预后均具有重要临床价值。