Comparisons of cardiac output in supine and lateral positions

Cardiac output was measured by thermodilution in 51 adult postcardiac surgical patients using three positions, supine, right lateral, and left lateral, each with 20 degrees backrest elevation. Measurements were taken 4 to 24 hours (M = 10.58) after surgery. Mean cardiac output was significantly different in the three positions, p = .03. This difference resulted from changes in stroke volume, p = .004, rather than changes in heart rate, p = .12. The largest variation occurred between cardiac outputs measured in the supine position and those measured in the left lateral position. Patients at greatest risk for variations in cardiac output with lateral postural change were those with a cardiac index less than 2.3 L/min/m2, those in whom the time elapsed since surgery was less than 12 hours, and those receiving either vasoactive drugs or mechanical ventilation. These results suggest that nurses need to measure cardiac output using a supine position to control for physiological changes that may occur with lateral postural change.     

Short- and long-term quantitation reproducibility of brain metabolites in the medial wall using proton echo planar spectroscopic imaging

Proton echo planar spectroscopic imaging (PEPSI) is a fast magnetic resonance spectroscopic imaging (MRSI) technique that allows mapping spatial metabolite distributions in the brain. Although the medial wall of the cortex is involved in a wide range of pathological conditions, previous MRSI studies have not focused on this region. To decide the magnitude of metabolic changes to be considered significant in this region, the reproducibility of the method needs to be established. The study aims were to establish the short- and long-term reproducibility of metabolites in the right medial wall and to compare regional differences using a constant short-echo time (TE30) and TE averaging (TEavg) optimized to yield glutamatergic information. 2D sagittal PEPSI was implemented at 3T using a 32 channel head coil. Acquisitions were repeated immediately and after approximately 2weeks to assess the coefficients of variation (COV). COVs were obtained from eight regions-of-interest (ROIs) of varying size and location. TE30 resulted in better spectral quality and similar or lower quantitation uncertainty for all metabolites except glutamate (Glu). When Glu and glutamine (Gln) were quantified together (Glx) reduced quantitation uncertainty and increased reproducibility was observed for TE30. TEavg resulted in lowered quantitation uncertainty for Glu but in less reliable quantification of several other metabolites. TEavg did not result in a systematically improved short- or long-term reproducibility for Glu. The ROI volume was a major factor influencing reproducibility. For both short- and long-term repetitions, the Glu COVs obtained with TEavg were 5-8% for the large ROIs, 12-17% for the medium sized ROIs and 16-26% for the smaller cingulate ROIs. COVs obtained with TE30 for the less specific Glx were 3-5%, 8-10% and 10-15%. COVs for N-acetyl aspartate, creatine and choline using TE30 with long-term repetition were between 2-10%. Our results show that the cost of more specific glutamatergic information (Glu versus Glx) is the requirement of an increased effect size especially with increasing anatomical specificity. This comes in addition to the loss of sensitivity for other metabolites. Encouraging results were obtained with TE30 compared to other previously reported MRSI studies. The protocols implemented here are reliable and may be used to study disease progression and intervention mechanisms.     

Abdominal hollowing and lateral abdominal wall muscles' activity in both healthy men & women: An ultrasonic assessment in supine and standing positions

The objective of this study was to investigate the effects of Abdominal Hollowing (AH) maneuver on External Oblique (EO), Internal Oblique (IO) and Transversus Abdominis (TrA) muscles in both healthy men and women during the two postures of supine and upright standing. The study was conducted on 43 asymptomatic volunteers (22 males and 21 females) aged 19-44 (27.8±6.4) years. Rehabilitative Ultrasonic Imaging (RUSI) was simultaneously performed to measure muscle thickness in both rest and during AH maneuvers while activation of the TrA during AH was controlled by Pressure Biofeedback (PBF) device. Mixed-model ANOVA with repeated measures design, and Pearson correlation tests were used to analyze the data. Muscle thickness of all muscles was significantly higher for male subjects (F>6.2, p<0.017). The interaction effect of gender and muscle status was significant only for IO (F=7.458, p=0.009) indicating that AH maneuver increased the thickness of IO in men. Interaction effect of posture and muscle status on muscular thickness indicated that changing position only affects the resting thickness of TrA (F=5.617, p=0.023). Standing posture significantly affected the TrA contraction ratio (t=3.122, p=0.003) and TrA preferential activation ratio (t=2.76, p=0.008). There was no relationship between age and muscle thickness (r=0.262, p=0.09). The PBF has been introduced as a clinical and available device for monitoring TrA activity, while RUSI showed that both TrA and IO muscles had activated after AH maneuver. We recommend performing further investigations using electromyography and RUSI simultaneously at more functional postures such as upright standing.     

Normal values of functional residual capacity in the sitting and supine positions

The measurement of functional residual capacity (FRC) has assumed new importance in the diagnosis of acute respiratory failure. However few reference values exist for FRC in supine positions for both sexes. We measured the FRC in 100 healthy subjects with the helium dilution closed circuit method in the sitting and supine positions. There were 50 women aged 20 to 63 years and 50 men aged 22 to 65 years. Fifty five subjects were smokers (25 women and 30 men) but no significant differences were found between FRC of smokers and nonsmokers. The FRC always decreased when the subject changed from the sitting to supine position. In this study, the correlation coefficients between FRC and height were statistically significant for both sexes, the influence of age and weight on FRC being negligible. Our results provide useful reference values for FRC in the supine position.     

Role of dangling when moving from supine to standing position

This article focuses on the cardiovascular adjustments that take place when an individual makes a change in his/her position, particularly when moving from the supine to the standing position (orthostasis). Some individuals may experience a drop in their blood pressure on assuming the standing position, which may lead to dizziness and/or fainting (orthostatic intolerance). Dangling, which is often an intermediary stage of assisting people into the sitting position with their legs hanging over the side of the bed, before moving them into the standing position, is therefore used to ensure that patients are moved safely. This can help to prevent notable reductions in blood pressure. Nurses, therefore, need to be aware of the cardiovascular changes and compensatory mechanisms that take place during orthostasis, in order to be able to make decisions not just about whether their patient can be moved out of bed, but so that it can be done safely without any of the adverse effects of orthostatic intolerance. Those at greatest risk of developing such adverse effects include those with diabetes mellitus, cardiovascular disease and also those with an age-related vagal dysfunction. Some pharmacological agents may also be implicated in contributing to orthostatic intolerance in some individuals. Recommendations for practice include ensuring that dangling the patient is incorporated as part of the procedure of slowly assisting patients out of bed, encouraging leg and foot movement and continually assessing the patient during the procedure. Should any patient show any sign of not tolerating the position change, the procedure should be halted and the patient assisted back into the supine position.     

Short-, mid-, and long-term reproducibility of the atrial signal-averaged electrocardiogram in healthy subjects: comparison with the conventional ventricular signal-averaged electrocardiogram

Although atrial signal-averaged electrocardiogram (SAECG) has been proposed for noninvasive identification of patients with atrial tachyarrhythmias, the substantial variability of the measurement limits the clinical value. The aim of the study was to assess the short- to long-term reproducibility of atrial SAECG and to compare it to that of the conventional ventricular SAECG in 51 healthy volunteers (30 men; age 32 +/- 8 years). In each subject, SAECG recordings were obtained using MAC-VU electrocardiograph and HiRES and PHiRES software (Marquette Medical Systems) and repeated after 5 minutes, 1 day, 1 week, and 1 month. Automatically detected onset and offset of the filtered QRS complex and P wave were subsequently corrected by two independent observers, and the averaged values were used for the analysis. Conventional ventricular SAECG parameters: filtered QRS duration (QRStot), low amplitude signal duration, and root mean square voltage (RMS) of the terminal 40 ms of QRS, and 5 atrial parameters: filtered P wave duration (Ptot), RMS of the terminal 40, 30, 20 ms, and of the entire P wave were obtained. Relative errors of different pairs of measures were used to assess the intrasubject reproducibility. QRStot and Ptot were the most reproducible parameters. The relative errors after 5 minutes, 1 day, 1 week, and 1 month were 0.8% to 2.4% for QRStot, and 1.3% to 4.2% for Ptot. For RMS voltages, the relative errors exceeded 15% in short-term and 20% in long-term recordings. Although Ptot was statistically less reproducible than QRStot, the reproducibility of the former was good and comparable to that of the QRStot. The reproducibility of the voltage parameters was significantly poorer than that of the duration parameters. The study showed a satisfactory short- and long-term reproducibility of Ptot in the atrial SAECG in healthy subjects. However, low reproducibility of the voltage parameters should be considered in clinical applications.     

Angiotensin II formation and endothelin clearance in ARDS patients in supine and prone positions

Objective: In patients with acute respiratory distress syndrome (ARDS), the prone position may enhance oxygenation by changing ventilation/perfusion ratio. In this study, we investigated whether the prone position affects the net balance between pulmonary endothelin (ET-1) and angiotensin II (Ang II) production and clearance, two metabolic functions of lung endothelial cells.¶Setting: Anaesthesiological intensive care unit of a university hospital.¶Patients: Ten ARDS patients (Murray score > 2.5) were studied in both the supine position (SP) and the prone position (PP).¶Measurements and design: Blood samples were taken simultaneously from the patient in SP for assessment of mixed venous and arterial ET-1 and Ang II concentrations, and plasma renin concentration (PRC). This was repeated after 60 min in SP, immediately after turning the patient into PP, and 60 min thereafter. Net arterial/mixed venous ET-1 clearances and net Ang II formations were calculated.¶Results: arterial oxygen tension increased from SP to PP by an average of 60 mmHg, about 20 %. Arterial ET-1 concentrations of ARDS patients were 1.57 ± 1.1 pg/ml (mean ± SD) and within the range of healthy persons. Net ET-1 clearances were negative in SP, indicating pulmonary release of ET-1, and did not change in PP. Arterial Ang II concentrations (73 ± 56 pg/ml) as well as PRC (126 ± 85 pg/ml) were markedly elevated. Net transpulmonary Ang II formation did not change.¶Conclusion: Acute changes of oxygenation in ARDS patients by positioning do not induce any short-term effects on pulmonary ET-1 net clearance or Ang II net formation.     

Respiratory effects on the reproducibility of cardiovascular autonomic parameters

The aim of this study was to assess the influence of breathing pattern on the reproducibility of the most commonly used heart rate and blood pressure variability parameters and baroreflex indices. 5-5 min ECG and blood pressure recordings were made and repeated for 10 healthy volunteers in supine rest on 10 consecutive days during spontaneous and 6 min(-1) patterned breathing. We investigated the following parameters: mean RR interval (RRI); the standard deviation of RR intervals (SDRR); the root mean square of successive differences in RRI (RMSSD); the percentage of RRIs which differed by 50% from the proceeding RRI (PNN50); mean systolic arterial pressure (SAP); the standard deviation of SAP (SAP SD); mean mean arterial pressure (MAP); mean diastolic blood pressure (DAP) and baroreflex indices from spontaneous sequence method (upBRS and downBRS) and from cross spectral analysis (LF alpha, HF alpha). To assess reproducibility for each parameter within- and between-subject variability values were calculated and the ratio of within- and between-subject variability was assessed. In addition, we calculated intraclass correlation coefficient (ICC). Compared to spontaneous respiration during 6 min(-1) patterned breathing the heart rate and blood pressure variability increased; upBRS, LF alpha and HF alpha increased, downBRS did not change. However, ICC showed good reproducibility for most parameters, which did not improve further with controlled breathing. In conclusion, respiration had a strong influence on the most widely used cardiovascular autonomic parameters. The controlling of breathing did not result in consistent improvement in their reproducibility.     

Changes in blood pressure in the sitting and standing positions in hypertensive patients

Ersoy S, Pinar R, Ersoy IH. International Journal of Nursing Practice 2011; 17 : 105–109 Changes in blood pressure in the sitting and standing positions in hypertensive patients Most guidelines for management of hypertension do not give special preference to a specific position of patient during blood pressure (BP) measurement, suggesting that BP readings taken with patients sitting, supine and standing are equivalent. The objective of this study was to examine whether there was any difference between BP readings with hypertensive participants comfortably sitting on chair and those with participants standing with the arm supported horizontally at the right atrial level. BP was measured twice each for 168 hypertensive patients (medicated and unmedicated) at sitting, standing and sitting positions, respectively, with a mercury‐filled column sphygmomanometer. We found significantly lower in systolic and diastolic BP readings in standing position than in sitting position. The present study indicates that the BP readings are related to the posture; thus, BP measured in different positions cannot automatically be regarded as equivalent.     

Comparison of cervical vertebral separation in the supine and seated positions using home traction units

This study was performed for the purpose of comparing the magnitude of cervical vertebral separation during cervical traction in supine and seated positions using home traction units. A repeated measures design with two within-subject factors (type of traction and time) was used. Seventeen asymptomatic volunteers received cervical traction in seated and supine position. Subjects received 5?minutes of static traction in sitting or supine using a force of 13.6?kg while in 15 degrees of neck flexion. A lateral radiograph of the cervical spine was taken before traction force was applied and after five minutes of static traction. Anterior and posterior distances between the inferior border of C2 and the superior border of C7 were measured by a radiologist. After supine traction there were significant increases (p=0.001) in posterior cervical vertebral separation compared to any changes after seated traction. There were no significant changes in anterior vertebral separation during either supine or seated traction positions (p=0.769). Supine cervical traction may be more effective for increasing posterior vertebral separation than seated cervical traction.     

Short- and long-term outcomes of older patients in intermediate care units

Objective To evaluate short- and long-term outcomes of elderly patients (≥ 65 years) treated at an intermediate care unit (IMCU) and to identify outcome predictors.Design and setting Prospective observational study in the IMCU of a university teaching hospital.Participants We studied 412 patients over 8 months, classified into three groups: under 65 years (control group, n = 158), 65–80 (n = 186), and > 80 (n = 68).Measurements At admission: APACHE II, TISS-28 first day, Charlson Index, diagnosis, and prior Barthel Index. Outcome measures: in-hospital mortality, length of stay, discharge destination, and 2-year mortality and readmissions. Data analysis included multivariate logistic regression and receiver operating characteristics area under the curve (ROC AUC).Results No statistically significant differences between groups were observed in hospital mortality (14.1%), discharge to a long-term facility (2.7%), or 2-year readmissions (1.2 ± 2.1). However, hospital stay was longer in patients aged 65–80 years (14 vs.10 days) and 2-year mortality was higher in those 65 or over (34% vs.10.6%). In the overall series in-hospital mortality was predicted by APACHE II, first-day TISS-28, and diagnosis (ROC AUC 0.81), and 2-year mortality by Charlson Index and age (ROC AUC 0.77). In the elderly patients 2-year mortality was predicted by Charlson and Barthel indices (ROC AUC 0.70).Conclusions Illness severity and therapeutic intervention at admission to IMCU were predictors of short-term mortality, whereas the strongest predictor of long-term mortality was comorbidity. Our results suggest that comprehensive assessment of elderly patients at admission to IMCUs may improve outcome prediction.Electronic supplementary material The electronic reference of this article is . The online full-text version of this article includes electronic supplementary material. This material is available to authorised users and can be accessed by means of the ESM button beneath the abstract or in the structured full-text article. To cite or link to this article you can use the above reference.This article is discussed in the editorial available at:     

Comparison between side-lying and standing positions for hip abductor strength assessment

BackgroundThe hip abductor muscles control the pelvis in the frontal plane and allow the maintenance of trunk position and dynamic balance during weight-bearing activities.ObjectiveTo compare the side-lying and standing positions for hip abductor strength assessment with regards to torque production and myolectric activity.MethodConcentric and eccentric hip abductor peak torque and total work, and myoelectric activity of the tensor fascia lata, gluteus medius, and inferior and superior portions of the gluteus maximus muscles were measured during maximal isokinetic tests for hip abductor strength in the side-lying and standing positions. The Wilcoxon test was used to compare variables between the positions.ResultsPeak torque values did not differ between side-lying and standing positions for both concentric and eccentric contraction modes (p > .05). During standing position, greater concentric total work was observed (p = .013). This position resulted in a lower activity of the tensor fascia lata muscle (p = .005) compared to side lying position. Myoelectric activity of gluteus medius, and inferior and superior portions of the gluteus maximus was similar between positions (p > .05).ConclusionBoth positions presented similar peak torque values and, during the standing position, a greater concentric total work and lesser activation of the tensor fascia lata was observed. Standing position can be used when emphasis on the superior portion of gluteus maximus over the tensor fascia lata is intended.     

仰、俯卧位磁共振多平面扫描在脑脊液鼻漏诊断中的应用

目的 探讨仰、俯卧位MR多平面扫描对脑脊液鼻漏的诊断价值。方法 回顾性分析20例脑脊液鼻漏患者的仰、俯卧位MR多平面扫描资料,包括常规轴位、矢状位、冠状位图像。并与术中所见相对照。结果 MRI清晰显示17例(17/20,85.00%)脑脊液鼻漏;漏口位于筛板顶部15例(15/20,75.00%),蝶筛隐窝、蝶窦各1例(1/20,5.00%)。另3例漏口MRI显示不清。俯卧位图像显示鼻窦内及鼻孔处脑脊液信号较仰卧位增多17例(17/20,85.00%),体位改变后MRI表现无明显变化3例(3/20,15.00%)。5例(5/20,25.00%)同时伴有脑疝。结论 仰、俯卧位MR多平面扫描可较准确地显示脑脊液鼻漏患者漏口位置,且可同时显示伴发的脑疝,变换体位有助于活动性脑脊液鼻漏的检出。     

Systematic review of patient handling activities starting in lying,sitting and standing positions

BACKGROUND: Over the last 20 years a number of methods have been recommended in professional guidelines for moving patients. This review was undertaken as it was recognized that there was a need for clinical work involving handling patients (systems of work and equipment) to be based on scientific evidence. AIMS: The aim of this paper is to report the methodology, search strategy and results relating to work involving the care, treatment and transfer of patients starting in lying, sitting and standing positions. METHODS: An unusual philosophical stance has been taken by appraising studies within a study type rather than comparatively. This facilitated the inclusion of a wide range of study designs (quantitative and qualitative). A string search was run on eight databases and supplemented by other search strategies. A published checklist was selected and inter-rater reliability established before the main review commenced. A systematic process for inclusion, exclusion, appraisal, extraction and synthesis was undertaken. RESULTS: Thirty-two studies were included: nine for activities with the patient starting in a lying position and 23 for the sitting position. No studies were found with respect to patient handling activities starting in a standing position. These data were synthesized into evidence statements. CONCLUSIONS: The evidence statements support the use of hoists (for nonweight bearing patients), standaids, sliding sheets (double thickness rollers), lateral transfer boards, walking belts and adjustable height beds and baths. It is suggested that these items should constitute a minimum equipment list for any clinical environment where patient handling takes place on a regular basis. The lack of research relating to patient handling in standing is of particular concern and it is recommended that this area should be a high research priority to address concerns about patient handling in rehabilitation activities.     

Short- and long-term effects of estrogen and synthetic anabolic hormone in postmenopausal osteoporosis

In 29 women with postmenopausal osteoporosis, the proportion of total bone surface undergoing resorption or formation was evaluated by microradiography of iliac crest biopsy samples before and after short-term (2(1/2)-4 months) and long-term (26-42 months for estrogen and 9-15 months for anabolic hormone) treatment. After estrogen administration, values for bone-resorbing surfaces decreased, although less prominently after long-term than after short-term therapy. The magnitude of this decrease was positively correlated with the pretreatment value for bone-resorbing surfaces (P < 0.001). When the pretreatment value for bone-resorbing surfaces was used as a covariable, estrogen and anabolic hormone appeared to be equally effective. For bone-forming surfaces, short-term therapy with either hormone had no effect but long-term therapy significantly decreased the values. Serum immunoreactive parathyroid hormone (IPTH) increased significantly after estrogen therapy; the change in IPTH was inversely related to the change in serum calcium (P < 0.001, sign test). We conclude that the primary effect of sex hormones in postmenopausal osteoporosis is to decrease the increased level of bone resorption, perhaps by decreasing the responsiveness of bone to endogenous parathyroid hormone. However, this favorable effect, at least in part, is negated after long-term treatment by a secondary decrease in bone formation. Our data are consistent with the concept that the maximal benefit that can be derived from sex hormone therapy in postmenopausal osteoporosis is arrest or slowing of the progession of bone loss.     

Short- and long-term effects of an intensive inpatient vision rehabilitation program

OBJECTIVE: To assess the effects of a visual rehabilitation program on visually impaired subjects' visual ability and ability to perform activities. DESIGN: Prospective observational study. SETTING: Telephone interviews of respondents in their homes the week before admission to the rehabilitation center and 3 months and 1 year after discharge from the rehabilitation center. PARTICIPANTS: A total of 178 consecutive patients from the Hines Blind Rehabilitation Center participated in development of the 48-item Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ-48). Data were analyzed for 95 who participated in all 3 administrations of the questionnaire. INTERVENTION: Comprehensive blind rehabilitation program (mean hospital admission, 40 d). MAIN OUTCOME MEASURE: The self-report ratings of patients' difficulty performing 48 activities on the VA LV VFQ-48. RESULTS: The increase in visual ability +/- standard deviation of .981+/-.482 logits (equivalent to an 8-line improvement in visual acuity on an Early Treatment of Diabetic Retinopathy Study chart) at 3 months postrehabilitation decreased to .682+/-.485 logits (equivalent to a loss of 2.5 lines of visual acuity on the same chart) 1 year postrehabilitation. The effect sizes measured at 3 months (2.035) and 1 year (1.495) indicate large treatment effects corresponding to statistically significant differences for the increase in visual ability at 3 months and 1 year postrehabilitation (paired 2-tailed t tests, P<.001) relative to pretreatment measures. The difference in visual abilities measured at 3 months and 1 year posttreatment also is statistically significant (P<.001). CONCLUSIONS: Treatment effects decreased over the 12-month follow-up period. However, the group of patients whose data were analyzed was still statistically and clinically significantly better at their 1-year follow-up than before beginning treatment.     

Cardiovascular autonomic regulation in fighter pilots: Lessons from active standing tests

Fighter pilots (FP) are exposed to flight accelerations and stressful situations that defy cardiovascular control during and after flight. FP presents a smaller adjustment in sympatho-vagal balance during tilt test after flight compared to baseline, suggesting a huge impact of flight on autonomic modulation to the heart. We undertake to test the hypothesis that FP will have a smaller vagal reentrance and lower sympathetic withdrawal during the recovery at the supine position after a prolonged active standing test that mimics flight hemodynamic demands. Twenty-one military personnel (20–34 years old), composed of 9 FP and 12 non-pilots (NP) matched by age, V̉O_2max and body mass index were enroled in the experimental protocol. R-R intervals were continuously recorded in the supine position for 15 min (SUP_baseline), during the prolonged active standing test (45 min) windowed in six 5 min time frames (from ORT1 to ORT6), and a recovery period in the supine position for 15 min (SUP_recovery). Heart rate variability was performed by spectral analysis to obtain the normalized low (LFn) and high (HFn) frequency components. The variation (Δ) from baseline (Δ = ORT6 − SUP_baseline) and from recovery (Δ = SUP_recovery–ORT6) periods were calculated. FP had a smaller ΔLFn (sympathetic mediated) and ΔHFn (vagal meditated) during recovery after active standing as compared to NP. Both groups showed similar changes in ΔLFn and ΔHFn during orthostatic stress compared to baseline, with no differences over time. Therefore, FP show a smaller vagal reentrance and a lower sympathetic reduction during recovery at supine following active standing compared to NP.