Peak expiratory flow in obese subjects in different positions

ABSTRACT

Objective: To analyze the peak expiratory flow (PEF) in obese subjects in standing (ST), seated (SE), supine (SU), prone (PR), and right and left lateral decubitus (RL and LL) positions. Methods: 36 obese volunteers, aged between 18 and 54 years, and nonsmokers, were evaluated by anthropometric data; spirometry; international physical activity questionnaire (IPAQ); and PEF in ST, SE, SU, PR, RL, and LL positions, randomly. Results: The mean age was 27.3 ± 7.4 years and BMI of 38.7 ± 3.2 kg/m²; IPAQ results: active (50%), irregularly active (25%), very active (16.7%), and sedentary (08.3%); spirometry results: FVC = 100.33%, FEV₁ = 92.83%, FEV₁/FVC ratio = 0.95, FEF_25-75% = 85.55%. The PEF (L/min) were within the normal range and there was no difference between the ST and SE (428.6 ± 100.9 and 430.0 ± 100.1). Comparing ST and SE to the other positions, in absolute and percent of predicted values (L/min and %), there was a decrease in the SU (85.4 ± 14.9), PR (401.1 ± 92.4 and 84.1 ± 14.4), RL (398.6 ± 94.7 and 83.3 ± 14.9) (p < 0.05), and there was no difference to SU (409.4 ± 102.8) and LL (410.3 ± 93.9 and 85.8 ± 14.5). Conclusion: The PEF of healthy obese are similar in the standing and seated positions. The PEF decreases in the lying positions, except for the LL, that could be used as an alternative for measurements.     

Predicted peak expiratory flow: differences across formulae in the literature

The study objectives were to examine the differences between Peak Expiratory Flow (PEF) formulae in the literature and to assess the potential impact of those differences on the interpretation of clinical guidelines for asthma management. We calculated 100% PEF values for hypothetical patients at the 50(th) percentile for height and weight and classified the percent predicted PEF into severity groups according to national asthma guidelines. Choosing different formulae could give an 18 year old man a 100% predicted PEF as low as 501 L/min and as high as 730 L/min (delta = 229 L/min); and a 35 year old woman a classification of severe (46%) using one, but moderate (57%) using another. Predicted PEF varied widely across formulae and choice of formula may alter guideline-based care. We propose recently published population-based equations as the reference standard for future asthma guidelines.     

哮喘控制测试与呼气峰流速在哮喘管理中的相关性研究

目的观察哮喘控制测试(ACT)与最大呼气峰流速(PEF)在哮喘管理中的作用,探讨二者在哮喘管理中的相关性。方法选择本院呼吸科就诊的40例非急性发作期支气管哮喘患者,均吸入糖皮质激素加长效β2受体激动剂进行缓解期的阶梯治疗。每日早、晚监测PEF值并记录。每4周随访1次,了解PEF、PEF占个人预计值的百分比(PEFpred%)及ACT监测情况。将ACT评分20分、≥20分的哮喘患者分别用A、B组表示,将PEFpred%80%、≥80%的哮喘患者分别用C、D组表示。结果 40例患者每4周随访1次,为期6个月,共进行了280次ACT评分和PEFpred%监测。其中A组62次,B组218次,C组65次,D组215次。A组PEFpred%为(67.80±8.21),显著低于B组(84.54±3.41)(P0.001);C组ACT评分为(17.37±2.20),显著低于D组(21.67±1.38)(P0.001)。ACT评分与PEFpred%具有线性相关关系(r=0.88,P0.001)。结论支气管哮喘患者的ACT评分与其PEF值具有较好的相关性。     

咳嗽峰流速对拔管结果预测的临床研究

目的 探讨咳嗽峰流速(CPEF)测定对患者拔管脱机结果的预测价值及对预后的影响.方法 选择本院重症监护病房(ICU)2006年11月-2007年12月的200例拔管脱机患者进行前瞻性研究.患者均为经口气管插管接呼吸机辅助呼吸超过24 h者,其意识清楚能合作,且均顺利通过自主呼吸试验30 min.拔管前嘱患者咳嗽,用呼吸机内置肺流量计测定CPEF,取3次最强咳嗽时流速的平均值作为最后测定值.拔管后仔细观察患者的咳嗽情况,按实际咳嗽能力大小将其分为强、中、弱3个等级,如果72 h内患者无需再插管即为拔管脱机成功,同时记录咳嗽能力与拔管结果之间的关系.结果 200例患者中172例拔管成功,28例拔管失败.拔管成功和失败的患者在性别、年龄、疾病严重程度、自主呼吸试验时生命体征等方面比较差异无统计学意义.CPEF是拔管结果的独立预测因子[比值比(OR)<1].区分拔管成功与否的CPEF最佳临界值是58.5 L/min,当CPEF≤58.5 L/min时预测拔管失败的特异性为68.0%,敏感性为71.4%;阳性预测值为0.16,阴性预测值为0.94.拔管脱机的患者咳嗽能力多为"强",极少数为"中";而失败患者咳嗽能力多为"中"或"弱",能力"强"者仅3例.结论 当患者自主呼吸能力逐渐恢复并达到能够完成自主呼吸试验时,气道条件的参数是决定患者拔管结果的重要预测指标.对意识清楚能合作、能通过自主呼吸试验的患者,CPEF是拔管结果强有力的预测因子,是影响拔管成功与否的独立危险因子.CPEF>58.5 L/min的患者拔管成功率高,预后较好;反之,≤58.5 L/ min的患者拔管成功率较低.导致失败的原因多为咯痰不利,咳嗽能力强的患者脱机成功率高,脱机失败的患者预后较差.     

机械通气患者呼气流速受限危险因素分析及其对患者预后的影响

目的 评估重症医学科机械通气患者中呼气流速受限的发病率,并确定与呼气流速受限相关的主要临床特征、危险因素和对患者预后的影响。方法 选取需要机械通气的患者202例,通过呼气末正压通气(PEEP)试验分为呼气流速受限组和非呼气流速受限组,在患者行机械通气12小时内测定呼吸力学指标,每日测定呼吸力学指标,连测3日。所有患者均行简化急性生理状态评分系统(SAPS)评分和器官衰竭评分(SOFA);改良的英国医学委员会呼吸困难评分量表（mMRC）评定呼吸困难严重程度。结果 22.77%的患者存在为呼气流速受限,其中脓毒性休克39例、ARDS 25例、失血性休克27例、慢性阻塞性肺疾病急性恶化32例、急性呼吸衰竭45例、心力衰竭12例和脑血管病合并肺炎22例。呼气流速受限患者的体重指数(BMI)较高,呼气流速受限与心脏病史、慢性肺病史有关(均P<0.05)。呼吸力学数据方面,呼气流速受限患者呼吸困难评分较差,最大气道阻力高,弹性阻力增加,具有较高的呼气末正压和内源性呼气末正压,峰值压较高,氧合指数较低(均P<0.05)。呼气流速受限组患者SOFA评分、SAPSⅡ评分均较高,机械通气时间更长,具有更高的病死率(均P<0.05)。结论 BMI高、肺病或心脏病史是重症医学科机械通气患者呼气流速受限的高危因素。呼气流速受限患者的呼吸力学参数更差。呼气流速受限患者机械通气时间较长,住院时间较长,病死率较高,预后差。     

呼气负压技术检测呼气流速受限在慢性阻塞性肺疾病中的应用

目的:应用呼气负压技术(NEP)检测慢性阻塞性肺疾病(COPD)患者的呼气流速受限(EFL)。方法:94例COPD患者在坐位及卧位时应用NEP方法检测EFL,即在患者潮气呼吸时于患者口部施加一个-5cmH2O的负压,通过比较施加负压前后的潮气流速-容积曲线来检测EFL。采用EFL五分法与经典的一秒钟用力呼气量(FEV1)方法进行比较。结果:55例COPD患者在坐位及卧位时均存在EFL;23例患者仅于卧位时存在EFL;16例患者坐位及卧位均无EFL。EFL五分法与经典FEV1方法判断肺功能损害程度较一致。EFL五分法与COPD患者的主观呼吸困难分级有更好的相关性。结论:①COPD患者在平静呼吸时EFL普遍存在;②NEP提供了一种简便、快速、无创的方法来检测EFL;③EFL五分法与COPD患者的呼吸困难分级有很好的相关性。     

Correlation between peak expiratory flow and abdominal muscle activity in elderly women while holding maximum expiration and performing the side bridge exercise

IntroductionExpiratory flow is important to minimize the risk of infection by expelling foreign substances from the lungs. Abdominal muscle activities primarily produce expiratory flow. However, data on the association of abdominal muscle activity during expiratory effort and abdominal exercise posture with expiratory flow rate is limited. This study aimed to assess the correlation between expiratory flow and abdominal muscle activity while holding maximum expiration and performing the side bridge exercise in elderly women.MethodsRectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscle activity was measured using electromyography in 14 elderly women (82.8 ± 6.7 years), who could walk independently while performing 2 tasks: holding their breath after maximum expiration in the crook-lying position (maximum expiration), and performing the side bridge exercise on their knees without breathing instruction (side bridge). Peak expiratory flow (PEF) was obtained using a peak flow meter. Correlations between PEF and the abdominal muscle activity were determined using the Spearman rank correlation coefficient.ResultsThe correlation coefficients between PEF and RA, EO, and IO activity while holding maximum expiration were 0.407 (p = 0.149), −0.345 (p = 0.227), and 0.732 (p = 0.003), respectively. The correlation coefficients between PEF and RA, EO, and IO activity while performing the side bridge exercise were −0.297 (p = 0.303), −0.552 (p = 0.041), and 0.147 (p = 0.615), respectively.ConclusionsHigher IO activity while holding maximum expiration or lower EO activity while performing the side bridge exercise was related to higher PEF. Thus, maximum expiration and abdominal exercise might be effective in the improvement or prevention of the decrease of expiratory flow.     

体位及呼气末正压对危重病患者中心静脉压的影响

目的观察不同体位及呼气末正压(PEEP)水平对机械通气(MV)危重患者中心静脉压(CVP)的影响。方法选择2005年12月—2006年3月重症加强治疗病房(ICU)进行MV并监测CVP的患者23例,观察患者在30°卧位及平卧位时PEEP0、3、6、9、12和15cmH2O(1cmH2O=0.098kPa)条件下CVP、心率(HR)、平均动脉压(MAP)、脉搏血氧饱和度(SpO2)及Riker镇静-躁动评分(SAS)的变化。结果相同PEEP条件下,患者两种体位的CVP、HR及MAP均无明显变化(P均>0.05);30°卧位SpO2显著高于平卧位(P<0.01)。患者体位由30°卧位调至平卧位及固定体位脱机时,CVP随PEEP水平升高而递增,至PEEP15cmH2O时明显高于其他PEEP水平(P均<0.05);脱机时SpO2明显低于不同PEEP水平时(P均<0.05);SAS随PEEP水平升高而递减,至PEEP15cmH2O时,SAS有所升高(P均<0.05);HR和MAP无明显变化。结论体位改变对MV患者的CVP无明显影响,随PEEP水平增加,CVP逐渐增加;改变体位与脱机均会使患者缺氧加重、躁动增加;维持患者原体位及PEEP水平而测量CVP,可增加患者的安全性与舒适性,减少医护人员工作量。     

Effect of different sitting postures on lung capacity, expiratory flow, and lumbar lordosis

OBJECTIVE: To investigate the effect of sitting posture on lung capacity and expiratory flow (LC-EF) and lumbar lordosis. DESIGN: Repeated measures on 1 group of subjects in 4 postures. SETTING: Laboratory. PARTICIPANTS: Seventy able-bodied volunteers. INTERVENTIONS: Postures were assumed randomly: normal, with full ischial support and flat lumbar support; slumped, with the pelvis positioned in the middle of seat while leaning against the backrest; against the back part of the seat without ischial support (WO-BPS), with partially removed ischial support and an enhanced lumbar support; and standing. MAIN OUTCOME MEASURES: For LC-EF, forced vital capacity, maximum forced expiratory flow, forced expiratory volume in 1 second, and peak expiratory flow; and lumbar lordosis. RESULTS: All LC-EF measures in standing were significantly superior to those in slumped and normal sitting, and 4 measures were significantly higher than in WO-BPS. In slumped sitting, LC-EF significantly decreased from that in normal sitting. WO-BPS sitting significantly increased 4 of the LC-EF measures from those in the normal sitting. Lumbar lordosis was the highest in standing and progressively decreased in WO-BPS, normal, and slumped sitting. CONCLUSIONS: Slumped sitting significantly decreased LC-EF and lumbar lordosis. Because it increases the lumbar lordosis and promotes LC-EF, the WO-BPS posture may be a better seating option for people sitting for a prolonged time.     

Sudden-onset Severe Acute Asthma: Clinical Features and Response to Therapy

Abstract. Objectives : To characterize patients with sudden onset of severe acute asthma (SAA) and to examine whether this presentation is associated with rapid recovery. Methods : Retrospective cohort study of ED visits to a teaching hospital. Subjects were aged 18–64 years, with SAA ( n = 225), denned as initial peak expiratory flow rate (PEFR) ≤40% of predicted. Visits for sudden-onset SAA (≤3 hours of symptoms) were characterized and multivariate logistic regression was used to examine the association between sudden onset and rapid recovery. Results : Patient visits for sudden-onset SAA had different triggers as compared with those for the slower-onset group (p = 0.006). The sudden-onset patients were less likely to report an upper-respiratory-tract infection (17% vs 40%) and more likely to have an unidentifiable trigger (40% vs 19%). In the multivariate logistic regression model, sudden onset was a strong independent predictor of rapid response [odds ratio (OR) 4.3, 95% confidence interval (CI) 1.6–11.6]. Sudden-onset visits were less likely to lead to admission (23% vs 43%, p = 0.03). Conclusions : These data suggest that different triggers may be involved in sudden-onset SAA and that sudden onset of symptoms is independently associated with rapid recovery. In their rapid deterioration and rapid response, these subjects share certain characteristics with "sudden asphyxic asthmatics" and may constitute a population suitable for further study of factors contributing to that condition. While these visits led to admission less frequently, prospective studies are necessary to provide information on duration of response and risk for relapse.     

Beneficial Effects of Albuterol Therapy Driven by Heliox versus by Oxygen in Severe Asthma Exacerbation

Objectives: To determine and define the beneficial effects of heliox‐driven albuterol therapy on severe asthma exacerbation and clinical factors that affect greater response. Methods: The authors conducted two randomized, double‐blinded, controlled trials in patients with severe asthma exacerbation. The first trial recruited 80 patients in the emergency department (ED). They received three consecutive doses of albuterol delivered by a nebulizer powered by either O₂ (O₂ group) or heliox (He/O₂= 80:20; heliox group). Changes in peak expiratory flow rate (PEF) were compared, and factors influencing the response to heliox‐driven albuterol therapy were identified. The second trial of 80 patients was conducted in older patients, a subpopulation associated with greater response in the first trial. Results: In the first trial, the heliox group had more rapid and greater improvement in PEF compared with the O₂ group. There tended to be more patients in the heliox group reaching the predetermined dischargeable PEF (>60% predicted) after three albuterol treatments (odds ratio, 2.58; 95% confidence interval = 1.03 to 6.46; p = 0.069). For patients eventually discharged from the ED, the ED stay was shorter by 10 minutes per patient in the heliox group compared with the O₂ group (p = 0.007). Logistic regression showed older age and lower pretreatment PEF to be associated with favorable heliox responses. The second trial, which recruited older patients (older than 40 years), showed greater improvement in PEF and dyspnea score with heliox‐driven albuterol therapy in patients with lower pretreatment PEF. Conclusions: Heliox‐driven albuterol may be a useful adjunct therapy for older asthmatic patients with severe asthma exacerbation.     

动脉自旋标记与多期增强技术评估不同年龄正常人肾血流

目的 采用MR动脉自旋标记（ASL）技术与MR多期增强评估不同年龄肾功能正常人群肾脏皮质血流的变化,并分析肾血流灌注与肾脏功能改变的关系。探讨ASL技术与多期增强技术评估肾血流灌注的差异。方法 收集本院行MR检查的肾脏无明显病变、肾功能正常的21~80岁受检者178名,按年龄段分为3组（21~40岁组,41~60岁组,61~80岁组）,每组各随机抽样20名进行分析。采用ASL技术获得肾血流量（RBF）;采用多期增强扫描获得肾皮质早期增强率（ER）;采用CKD-EPI公式估算肾小球滤过率（eGFR）。比较不同年龄组间RBF、ER和eGFR值,并分析其与年龄的相关性。结果 3组间RBF、eGFR比较差异均有统计学意义（P均<0.05）,且21~40岁组与61~80岁组差异有统计学意义（P<0.05）,余组间两两比较差异无统计学意义（P均>0.05）;两两组间比较eGFR值差异均有统计学意义（P均<0.05）。3组间ER差异无统计学意义（P=0.05）。双肾RBF、ER、eGFR均与年龄呈负相关（r=-0.37、-0.38、-0.87,P均<0.01）;RBF、ER与eGFR间均无相关性（r=0.208、0.223,P=0.111、0.087）;RBF与ER无相关性（r=0.015,P=0.911）。结论 正常肾功能人群随年龄增长,肾功能、肾血流量逐渐减低。ASL技术较多期增强技术对年龄增长导致的肾皮质血流的改变更加敏感。     

Psychomotor and cognitive effects of piribedil, a dopamine agonist, in young healthy volunteers

Piribedil is a dopamine agonist acting on D2 and D3 central nervous system dopamine receptors. This drug has been administered to 12 young healthy male volunteers (age 22 +/- 2 years) according to a single center randomized, double-blind, two ways cross-over, placebo controlled trial, including a washout period of one week. Placebo and piribedil were administered by a single intravenous infusion over 2 h (3 mg). Psychomotor performance and cognitive functions were assessed through a standardized and computerized psychometric tests battery and a continuous electroencephalogram (EEG) mapping. Piribedil improved simple reaction time (P=0.02), immediate (P=0.045 and 0.004), and delayed free recall (P=0.05), dual coding test (P=0.02) and increased theta and fast beta waves on the EEG (P < 0.05 and 0.001, respectively). No deleterious effect was observed on the tests exploring attention and concentration via the other procedures. It is concluded that a single intravenous perfusion of piribedil 3 mg improves alertness and the information processing speed within the central nervous system, in healthy volunteers.     

Weight distribution in standing and sitting positions,and weight transfer during reaching tasks,in seated stroke subjects and healthy subjects

Background and Purpose. The recovery of sitting balance after a stroke is assumed to be essential to obtain independence in other vital functions. The purpose of the present study was to investigate weight distribution while sitting and standing still, and weight transfer during seated reaching tasks performed by stroke subjects and healthy subjects. Method. The study was cross‐sectional. Twenty‐one stroke subjects and 21 healthy subjects, matched by age and gender, participated. Main measures were weight distribution while standing and sitting still, and displacements of centre of pressure (COP) during seated reaching tasks. Data were collected using a balance performance monitor (BPM), including software. Results. Stroke subjects had less symmetrical weight distribution in standing than that of healthy subjects (p < 0.001). No significant differences between the groups were found while sitting still, and no associations between asymmetries in standing still and sitting positions within individual stroke subjects were found. Neither did the degree of weight distribution in sitting correspond to COP displacements in seated reaching tasks. However, COP displacement patterns in reaching tasks in the seated position were different in stroke subjects from those of healthy subjects. Stroke subjects showed more lateral displacement when reaching forwards (p < 0.001), and less lateral displacement when reaching sideways to the unaffected side (p = 0.01). Conclusion. COP displacement patterns in stroke subjects deviate more than those of healthy subjects in seated reaching tasks. The deviating COP displacement patterns are discussed as a possible dysfunction in the ability to make postural adjustments and learn an efficient movement pattern. Copyright © 2007 John Wiley & Sons, Ltd.     

Clinical evaluation of diminished early expiratory flow (DEEF) ventilation in mechanically ventilated COPD patients

Objective To evaluate the cardiopulmonary effects, especially the end-expiratory lung volume (EEV) and ventilation inhomogeneity during diminished early expiratory flow ventilation (DEEF), which resembles pursed-lips breathing, with the conventional intermitent positive pressure ventilation (IPPV) in postoperative mechanically ventilated patients with chronic obstructive pulmonary disease (COPD).Design A prospective study measuring cardiopulmonary parameters during IPPV, DEEF, and positive end-expiratory pressure (PEEP) as a control mode. In the PEEP mode, PEEP values were chosen such that the mean airway pressure during a breath cycle was equal to that during the DEEF mode, which was higher than the conventional IPPV mode.Setting Surgical intensive care unit of a university hospital.Patients 20 postoperative mechanically ventilated COPD patients who were optimally pretreated and had normal blood oxygenation.Interventions Measurements were started in the IPPV (IPPV₁) mode, continued in a randomized order with DEEF or PEEP, and completed with a second IPPV (IPPV₂) mode, with 1 h equilibration time in each mode before each measurement.Measurements and results A multi-breath indicator gas wash-out test was used to calculate the EEV and ventilation inhomogeneity. There was a 9% increase (p<0.05) in the mean EEV during both the DEEF and PEEP mode compared to IPPV. No significant changes in the ventilation inhomogeneity and deadspace fractions or the hemodynamic parameters were found during the different ventilatory modes.Conclusions There was no improvement in pulmonary and hemodynamic parameters during the DEEF mode in comparison to the IPPV mode. The small increase in EEV during DEEF was probably caused by the slightly higher mean expiratory pressures as in the PEEP mode. However, this had no effect on the hemodynamic parameters. As we could not observe any improvement with the DEEF ventilation in our optimally pretreated postoperative COPD patients, we do not advise applying this therapy in this group of patients, since this mode of ventilation may cause barotrauma if not monitored adequately.     

Expiratory muscle strength training in persons with multiple sclerosis having mild to moderate disability: effect on maximal expiratory pressure, pulmonary function, and maximal voluntary cough

OBJECTIVE: To determine the effect of expiratory muscle strength training (EMST) on maximal expiratory strength, pulmonary function, and maximal voluntary cough in persons with multiple sclerosis (MS) having mild to moderate disability. DESIGN: Before-after trial. SETTING: Assessments were completed in the privacy of the subject's home or exercise physiology laboratory. PARTICIPANTS: Seventeen persons with MS were age- and sex-matched to 14 healthy controls. INTERVENTION: Eight weeks of EMST and 4 weeks of detraining. MAIN OUTCOME MEASURES: Maximal respiratory pressures, pulmonary function, and maximal voluntary cough were assessed 3 times (pretraining, posttraining, detraining). Maximal expiratory pressure (MEP) was assessed weekly and training intensity adjusted based on the new measurement. RESULTS: Subjects with MS had lower MEP, decreased pulmonary function, and weaker maximal voluntary cough at each assessment. EMST increased MEP and peak expiratory flow. However, improvement in maximal voluntary cough only occurred in subjects with a moderate level of disability when the MS group was subdivided into mild and moderate disability levels based on the Expanded Disability Status Scale. CONCLUSIONS: EMST is a viable tool to enhance the strength of the respiratory muscles. However, further work is needed to determine the best parameters to assess change in cough following EMST.     

The individual variation in pharmacokinetics and pharmacodynamics of furosemide in young normal male subjects

Abstract. Following a 24 h control period in the ward 80 mg furosemide was injected intravenously to ten young healthy, male volunteers. The serum clearance of furosemide (Cl_s) was between 140 and 201 ml min^-1 and on the average the renal clearance was 66% of Cl_s. During the initial 30 min period a maximum additional excretion rate of sodium of 3·3 mmol min^-1 was reached at an excretion rate of 0·8 mg furosemide min^-1. A marked initial drop in creatinine clearance (Cl_cr) was noted and Cl_{cr(24 h)} showed an average decrease of 12% after the drug administration. The serum concentration of potassium was decreased at 1 and 2 h after the injection and of sodium from 2 h and on. The concentration of albumin in serum increased by 3% ( P < 0·05) already after 5 min. After 2 h a maximum increase of 14% was reached. After 8 min diastolic blood pressure was increased by 13% ( P < 0·05), whereas systolic blood pressure reached a significant decrease gradually (7% after 3 h).     

Dynamic evaluation of near-infrared peripheral oximetry in healthy volunteers: A comparison between INVOS and EQUANOX

Purpose

The present study aimed to compare peripheral regional tissue oxygen saturation (rSO₂) values and desaturation/resaturation rates given by INVOS and EQUANOX devices.

Materials and methods

Twenty healthy volunteers were investigated during 4 experimental steps: baseline, hyperoxia, ischemia, and reperfusion. For each volunteer, 2 sensors INVOS and 2 sensors EQUANOX were placed on both left and right calves. Blood pressure, heart rate, and peripheral pulse oximetry were monitored.

Results

Peripheral rSO₂ ranged from 40% to 95% (INVOS) and from 47% to 100% (EQUANOX): 81 ± 12 vs 82 ± 9 (P = .469). A significant relationship was found at baseline between absolute values of INVOS and EQUANOX (n = 40; R² = 0.159; P = .011). Bias was − 0.4%, and limits of agreement were ± 15.1%. The percent maximum differences vs baseline values during dynamic maneuvers were 33% ± 19% (95% confidence interval, 24-42) and 21% ± 14% (95% confidence interval, 15-28) for INVOS and EQUANOX, respectively. No significant relationship was observed between percent maximum differences in INVOS and EQUANOX (n = 20; R² = 0.128; P = .122). Rates of desaturation/resaturation during occlusive vascular tests were 3.65% per minute vs 2.36% per minute (P = .027) and 30.42% per minute vs 16.28% per minute (P = .004) for INVOS and EQUANOX, respectively.

Conclusions

INVOS and EQUANOX are not comparable in measuring both absolute values and dynamic changes of peripheral rSO₂ and near-infrared spectroscopy–derived parameters during occlusion vascular tests.