Chest compression rates during cardiopulmonary resuscitation are suboptimal: a prospective study during in-hospital cardiac arrest

BACKGROUND

Recent data highlight a vital link between well-performed cardiopulmonary resuscitation (CPR) and survival after cardiac arrest; however, the quality of CPR as actually performed by trained healthcare providers is largely unknown. We sought to measure in-hospital chest compression rates and to determine compliance with published international guidelines.

METHODS AND RESULTS

We developed and validated a handheld recording device to measure chest compression rate as a surrogate for CPR quality. A prospective observational study of adult cardiac arrests was performed at 3 hospitals from April 2002 to October 2003. Resuscitations were witnessed by trained observers using a customized personal digital assistant programmed to store the exact time of each chest compression, allowing offline calculation of compression rates at serial time points. In 97 arrests, data from 813 minutes during which chest compressions were delivered were analyzed in 30-second time segments. In 36.9% of the total number of segments, compression rates were <80 compressions per minute (cpm), and 21.7% had rates <70 cpm. Higher chest compression rates were significantly correlated with initial return of spontaneous circulation (mean chest compression rates for initial survivors and nonsurvivors, 90+/-17 and 79+/-18 cpm, respectively; P=0.0033).

CONCLUSIONS

In-hospital chest compression rates were below published resuscitation recommendations, and suboptimal compression rates in our study correlated with poor return of spontaneous circulation. CPR quality is likely a critical determinant of survival after cardiac arrest, suggesting the need for routine measurement, monitoring, and feedback systems during actual resuscitation.

A new oscillometric method for pulse wave analysis: comparison with a common tonometric method

In the European Society of Cardiology-European Society of Hypertension guidelines of the year 2007, the consequences of arterial stiffness and wave reflection on cardiovascular mortality have a major role. But the investigators claimed the poor availability of devices/methods providing easy and widely suitable measuring of arterial wall stiffness or their surrogates like augmentation index (AIx) or aortic systolic blood pressure (aSBP). The aim of this study was the validation of a novel method determining AIx and aSBP based on an oscillometric method using a common cuff (ARCSolver) against a validated tonometric system (SphygmoCor). aSBP and AIx measured with the SphygmoCor and ARCSolver method were compared for 302 subjects. The mean age was 56 years with an s.d. of 20 years. At least two iterations were performed in each session. This resulted in 749 measurements. For aSBP the mean difference was -0.1 mm Hg with an s.d. of 3.1 mm Hg. The mean difference for AIx was 1.2% with an s.d. of 7.9%. There was no significant difference in reproducibility of AIx for both methods. The variation estimate of inter- and intraobserver measurements was 6.3% for ARCSolver and 7.5% for SphygmoCor. The ARCSolver method is a novel method determining AIx and aSBP based on an oscillometric system with a cuff. The results agree with common accepted tonometric measurements. Its application is easy and for widespread use.

Reverse-micelle-induced porous pressure-sensitive rubber for wearable human-machine interfaces

A novel method to produce porous pressure-sensitive rubber is developed. For the controlled size distribution of embedded micropores, solution-based procedures using reverse micelles are adopted. The piezosensitivity of the pressure sensitive rubber is significantly increased by introducing micropores. Using this method, wearable human-machine interfaces are fabricated, which can be applied to the remote control of a robot.

Gastric tone measured by an electronic barostat in health and postsurgical gastroparesis

Using a gastric barostat we have studied interdigestive variations in gastric tone and its response to gastric distention in 17 healthy volunteers and 5 patients with postsurgical gastroparesis. The barostat measures tone by monitoring the volume of air within a flaccid intragastric bag, maintained at a constant, preselected pressure level by an electronic feedback mechanism. In healthy individuals, inter-digestive variations in gastric tone were phase-locked in advance of duodenal interdigestive motor activity and consisted of three sequential periods; a quiescence period, an intermediate period, and a period of activity. In contrast to controls, gastroparetic patients presented significantly larger intragastric volume at low intragastric pressure (6 mmHg). Gastric distention (14 mmHg) resulted in significantly reduced extension ratio and phasic motor response in the gastric remnant. Furthermore, distention elicited a symptomatic response that resembled their postcibal syndrome (epigastric fullness, pain, nausea). These data suggest that postsurgical gastroparesis is associated with impaired tone of the residual gastric pouch.

Super-elastic graphene ripples for flexible strain sensors

In this study, we report a buckling approach for graphene and graphene ribbons on stretchable elastomeric substrates. Stretched polydimethylsiloxane (PDMS) films with different prestrains were used to receive the transferred graphene, and nanoscale periodical buckling of graphene was spontaneously formed after strain release. The morphology and periodicity of the as-formed graphene ripples are dependent strongly on their original shapes and substrates' prestrains. Regular periodicity of the ripples preferred to form for narrow graphene ribbons, and both the amplitude and periodicity are reduced with the increase of prestrain on PDMS. The graphene ripples have the ability to afford large strain deformation, thus making it ideal for flexible electronic applications. It was demonstrated that both graphene ribbon and nanographene film ripples could be used for strain sensors, and their resistance changes upon different strains were studied. This simple and controllable process of buckled graphene provides a feasible fabrication for graphene flexible electronic devices and strain sensors due to its novel mechanical and electrical properties.

Determination of left ventricular chamber stiffness from the time for deceleration of early left ventricular filling

BACKGROUND

A noninvasive measure of left ventricular (LV) chamber stiffness (KLV) would be clinically useful. Our theoretical analysis predicts that KLV can be calculated from the time for deceleration of LV early filling (tdec) by [formula: see text] where p = density of blood, L = effective mitral length, and A = mitral area.

METHODS AND RESULTS

We tested this hypothesis in eight conscious dogs instrumented for measurement of LV pressure (P) with use of a micromanometer and volume (V) with use of sonomicrometers. KLV was determined as the slope of the late diastolic portion of the LV P-V loop. KLV was varied from 0.99 +/- 0.35 to 2.58 +/- 0.92 mm Hg/mL with use of three graded doses of phenylephrine. We assumed that p = 1.0 and that L/A = 3.4. Thus, we predicted that KLV = (0.08/tdec)2. The LV filling pattern was determined from the derivative of LV volume (dV/dt). tdec was measured from peak early filling to the end of early filling. Predicted KLV and actual KLV were closely correlated (r = .94, SEE = 0.06 mm Hg/mL, P < .05). The regression line was close to the line of identity (slope = 0.95, intercept = 0.13 mm Hg/mL). Dobutamine did not alter the relation between tdec and KLV.tdec determined from the mitral valve flow velocity measured with Doppler echocardiography correlated well with that measured by dV/dt (r = .89, P < .01) but was 0.02 seconds longer. KLV-calculated tdec from the corrected Doppler tdec provided a good estimate of measured KLV (r = .75, SEE = 0.5 mm Hg/mL, P < .01).

CONCLUSIONS

LV chamber stiffness can be determined from the time for deceleration of LV early filling, which can be measured noninvasively.

Site of airway obstruction in pulmonary disease: direct measurement of intrabronchial pressure

To partition the central and peripheral airway resistance in awake humans, a catheter-tipped micromanometer sensing lateral pressure of the airway was wedged into the right lower lobe of a 3-mm-ID bronchus in 5 normal subjects, 7 patients with chronic bronchitis, 8 patients with emphysema, and 20 patients with bronchial asthma. We simultaneously measured mouth flow, transpulmonary pressure, and intra-airway lateral pressure during quiet tidal breathing. Total pulmonary resistance (RL) was calculated from transpulmonary pressure and mouth flow and central airway resistance (Rc) from intra-airway lateral pressure and mouth flow. Peripheral airway resistance (Rp) was obtained by the subtraction of Rc from RL. The technique permitted identification of the site of airway resistance changes. In normal subjects, RL was 3.2 +/- 0.2 (SE) cmH2O.l-1.s and the ratio of Rp to RL was 0.24 during inspiration. Patients with bronchial asthma without airflow obstruction showed values of Rc and Rp similar to those of normal subjects. Although Rc showed a tendency to increase, only Rp significantly increased in those patients with bronchial asthma with airflow obstruction and patients with chronic bronchitis and emphysema. The ratio of Rp to RL significantly increased in three groups of patients with airflow obstruction (P less than 0.01). These observations suggest that peripheral airways are the predominant site of airflow obstruction, irrespective of the different pathogenesis of chronic airflow obstruction.

Pressure distribution under symptom-free feet during barefoot standing

The plantar pressure distributions for a large heterogeneous sample of feet (N = 107) were collected during barefoot standing using a capacitance mat. From these data, the function of the foot during standing was characterized. Peak pressures under the heel (139 kPa) were, on average, 2.6 times greater than forefoot pressures (53 kPa). Forefoot peak pressures were usually located under the second or third metatarsal heads. No significant relationship was found between body weight and the magnitude of peak pressure. The concepts of a transverse arch at the level of the metatarsal heads and a "tripod" theory of load distribution were not substantiated by this study. Load distribution analysis showed that the heel carried 60%, the midfoot 8%, and the forefoot 28% of the weightbearing load. The toes were only minimally involved in the weightbearing process. Examples of unusual distributions are shown; finally, a checklist is provided to aid the clinician in evaluating plantar pressure findings.

Highly stretchable and wearable graphene strain sensors with controllable sensitivity for human motion monitoring

Because of their outstanding electrical and mechanical properties, graphene strain sensors have attracted extensive attention for electronic applications in virtual reality, robotics, medical diagnostics, and healthcare. Although several strain sensors based on graphene have been reported, the stretchability and sensitivity of these sensors remain limited, and also there is a pressing need to develop a practical fabrication process. This paper reports the fabrication and characterization of new types of graphene strain sensors based on stretchable yarns. Highly stretchable, sensitive, and wearable sensors are realized by a layer-by-layer assembly method that is simple, low-cost, scalable, and solution-processable. Because of the yarn structures, these sensors exhibit high stretchability (up to 150%) and versatility, and can detect both large- and small-scale human motions. For this study, wearable electronics are fabricated with implanted sensors that can monitor diverse human motions, including joint movement, phonation, swallowing, and breathing.

Validation of a new non-invasive portable tonometer for determining arterial pressure wave and pulse wave velocity: the PulsePen device

OBJECTIVE

To validate a new, small portable tonometer (PulsePen) that is able to assess carotid artery pressure and to measure pulse wave velocity (PWV) non-invasively. Its software provides absolute arterial pressure values, an assessment of arterial pulse wave contours, an estimation of reflection waves and measurements of PWV.

DESIGN AND METHODS

Two validation studies were carried out. The aim of the first study was to compare arterial pressure values and pulse wave contours recorded in the carotid artery using the PulsePen versus intra-arterial simultaneous measurements in 10 patients undergoing cardiac catheterization. The pulse wave contour was assessed using Fourier analysis. The comparison between the two methods showed no difference in arterial pressure wave spectral moduli from harmonics 1 to 6. The second study compared PWV measurements taken with the PulsePen (one tonometer) and measurements performed with two Millar tonometers in 68 subjects (32 men, 36 women). PulsePen measurements were realized as two consecutive measurements in the carotid and femoral arteries, both synchronized by electrocardiogram. The pulse wave transit time was calculated as the difference between the time delay of the femoral pulse wave and the carotid pulse wave in relation to the R wave of the electrocardiogram. These measurements were compared with PWV obtained by simultaneous carotid and femoral measurements with the two Millar tonometers. No difference between the two methods was found, with a variation coefficient of 7.7%. The variation coefficients of the inter-observer and intra-observer reproducibility for the PulsePen were 7.9 and 7.2%, respectively.

CONCLUSIONS

These results show that the PulsePen enables an easy and reliable evaluation of central arterial pressure and stiffness in clinical ambulatory practice, especially in high-risk patients in whom arterial stiffness has been shown to be a significant indicator of morbidity and mortality.

Application of topographical methods to clinical esophageal manometry

OBJECTIVE

Topographical manometric methods have improved the understanding of esophageal peristalsis in research applications but require a large number of recording sensors. Commonly used methods limited to four sensors were compared to topographical methods to determine whether the latter also had significant clinical utility.

METHODS

Two hundred twelve patients referred for esophageal manometry were studied with a data acquisition system having 21 intraluminal recording sites, and the findings were analyzed independently using both limited (pull-through plus four recording sites) and topographical approaches (all sites). Discrepant results were clarified using supportive clinical data.

RESULTS

The two methods were in diagnostic agreement in 187 cases (88.2%). Topographical methods correctly identified all 26 patients with achalasia within the group with aperistalsis (n = 36). The limited methods could not confidently identify six achalasia patients and were significantly less effective in segregating aperistaltic disorders (p < 0.05 across methods). Topographical methods alone detected evidence of incomplete lower esophageal sphincter relaxation in 12 additional patients, eight of whom had clinical data supporting the findings. Topographical methods identified the upper margin of the lower sphincter in all but three subjects (1.4%); limited methods could not identify this location in these and five additional subjects (3.8%) and differed from the topographical measurement by > or = 2 cm in 11.9% of cases.

CONCLUSIONS

Topographical methods are more accurate than commonly used methods in diagnosing the type of severe motor dysfunction and provide additional information important in the clinical practice of esophageal manometry.

Triboelectric active sensor array for self-powered static and dynamic pressure detection and tactile imaging

We report an innovative, large-area, and self-powered pressure mapping approach based on the triboelectric effect, which converts the mechanical stimuli into electrical output signals. The working mechanism of the triboelectric active sensor (TEAS) was theoretically studied by both analytical method and numerical calculation to gain an intuitive understanding of the relationship between the applied pressure and the responsive signals. Relying on the unique pressure response characteristics of the open-circuit voltage and short-circuit current, we realize both static and dynamic pressure sensing on a single device for the first time. A series of comprehensive investigations were carried out to characterize the performance of the TEAS, and high sensitivity (0.31 kPa(-1)), ultrafast response time (<5 ms), long-term stability (30,000 cycles), as well as low detection limit (2.1 Pa) were achieved. The pressure measurement range of the TEAS was adjustable, which means both gentle pressure detection and large-scale pressure sensing were enabled. Through integrating multiple TEAS units into a sensor array, the as-fabricated TEAS matrix was capable of monitoring and mapping the local pressure distribution applied on the device with distinguishable spatial profiles. This work presents a technique for tactile imaging and progress toward practical applications of nanogenerators, providing potential solutions for accomplishment of artificial skin, human-electronic interfacing, and self-powered systems.

Noninvasive Measurement of Heartbeat, Respiration, Snoring and Body Movements of a Subject in Bed via a Pneumatic Method

We have developed a noninvasive pneumatics-based system by which to measure heartbeat, respiration, snoring, and body movements of a subject in bed. A thin, air-sealed cushion is placed under the bed mattress of the subject and the small movements attributable to human automatic vital functions are measured as changes in pressure using a pressure sensor having an almost flat frequency response from 0.1 to 5 kHz and a sensitivity of 56 mV/Pa. Using the newly developed system, heartbeat, respiration, apnea, snoring and body movements are clearly measured. In addition, the optimal signal-to-noise (S/N) ratio by which to evaluate the reliability of the heart rate measurement is presented. Heart rates were measured for four different body postures, 13 different subjects, four different bed mattresses, and three different sensor positions. For these measurements, the S/N ratios ranged from 15.9 to 23.5 dB, and so were determined to be reliable.

Flexible three-axial force sensor for soft and highly sensitive artificial touch

A soft tactile sensor able to detect both normal and tangential forces is fabricated with a simple method using conductive textile. Owing to the multi-layered architecture, the capacitive-based tactile sensor is highly sensitive (less than 10 mg and 8 μm, for minimal detectable weight and displacement, respectively) within a wide normal force range (potentially up to 27 N (400 kPa)) and natural touch-like tangential force ranges (from about 0.5 N to 1.8 N). Being flexible, soft, and low cost, this sensor represents an original approach in the emulation of natural touch.

Quantifying EGJ morphology and relaxation with high-resolution manometry: a study of 75 asymptomatic volunteers

Our aim was to define normal esophagogastric junction (EGJ) morphology and relaxation characteristics using high-resolution manometry (HRM). To this end, 75 asymptomatic controls underwent HRM with a solid-state manometric assembly incorporating 36 circumferential sensors spaced at 1-cm intervals positioned to record from the hypopharynx to the stomach. Ten 5-ml water swallows were obtained. EGJ relaxation was quantified by 1) nadir pressure, 2) the lowest 3-s mean residual pressure after swallow (E-sleeve), and 3) the transsphincteric gradient 2-6 s after swallowing measured from 2 cm above to 2 cm below the EGJ. A new parameter, integrated relaxation resistance (IRR), was also calculated. The IRR calculation accounted for both the duration of EGJ relaxation and instantaneous E-sleeve-type relaxation pressures during the entire interval of relaxation. The means and ranges (5-95th percentile) for nadir lower esophageal sphincter relaxation pressure (mean: 3.9 mmHg, range: 0-10.1 mmHg) and E-sleeve relaxation pressure (mean: 8.1 mmHg, range: 4.1-15.1 mmHg) were consistent with previously reported values. The mean relaxation interval was 7.95 +/- 0.2 s (mean +/- SE), whereas the median relaxation pressure during that interval was 10.7 +/- 0.5 mmHg (mean +/- SE). Mean IRR was 1.3 mmHg/s (95th percentile: 3.0 mmHg/s). Mean EGJ length was 3.7 cm. In conclusion, HRM provides a seamless dynamic representation of pressure within and across the EGJ. In addition to providing conventional EGJ relaxation parameters, this technology also creates opportunities to quantify more precise measures of EGJ relaxation and morphology.

Reliability of pelvic floor muscle strength assessment using different test positions and tools

AIMS

The aims of this study were to determine the intra-therapist reliability for digital muscle testing and vaginal manometry on maximum voluntary contraction strength and endurance. In addition, we assessed how reliability varied with different tools and different testing positions.

METHODS

Subjects included 20 female physiotherapists. The modified Oxford scale was used for the digital muscle testing, and the Peritron perineometer was used for the vaginal resting pressure and vaginal squeeze pressure assessments. Strength and endurance testing were performed. The highest of the maximum voluntary contraction scores was used in strength analysis, and a fatigue index value was calculated from the endurance repetitions. Bent-knee lying, supine, sitting, and standing positions were used. The time interval for between-session reliability was 2-6 weeks.

RESULTS

Kappa values for the between-session reliability of digital muscle testing were 0.69, 0.69, 0.86, and 0.79 for the four test positions, respectively. Intra-class correlation coefficient (ICC) values for squeeze pressure readings for the four positions were 0.95, 0.91, 0.96, and 0.92 for maximum voluntary contraction, and 0.05, 0.42, 0.13, and 0.35 for endurance testing. ICC values for resting pressure were 0.74, 0.77, 0.47, and 0.29.

CONCLUSIONS

Reliability of digital muscle testing was very good in sitting and good in the other three positions. vaginal resting pressure demonstrated very good reliability in all four positions for maximum voluntary contraction, but was unreliable for endurance testing. Vaginal resting pressure was not reliable in upright positions. Both measurement tools are reliable in certain positions, with manometry demonstrating higher reliability coefficients.

Quantifying esophageal peristalsis with high-resolution manometry: a study of 75 asymptomatic volunteers

The vastly enhanced spatial resolution of high-resolution manometry (HRM) makes it possible to simultaneous monitor contractile activity over the entire length of the esophagus. The aim of this investigation was to define the essential features of esophageal peristalsis in novel HRM paradigms and establish their normative values. Ten 5-ml water swallows were recorded in each of 75 asymptomatic controls with a solid-state manometric assembly incorporating 36 circumferential sensors spaced at 1-cm intervals positioned to record from the hypopharynx to the stomach. The data set was then subjected to intensive computational analysis to distill out the essential characteristics of normal peristalsis. Esophageal peristalsis was conceptualized in terms of a proximal contraction, a distal contraction, and a transition zone separating the two. Each contractile segment was quantified in length and then normalized among subjects to summarize focal fluctuation of contractile amplitude and propagation velocity. Furthermore, the temporal and spatial characteristics of the transition zone separating the proximal and distal contraction were quantified. For each paradigm, graphics were developed, establishing median values along with the 5th to 95th percentile range of observed variation. In addition, the synchronization between peristalsis and esophagogastric junction relaxation was analyzed using a novel concept of the outflow permissive pressure gradient. We performed a detailed analysis of esophageal peristalsis aimed at quantifying its essential features and, in so doing, devised new paradigms for the quantification of peristaltic function that will hopefully optimize the utility of HRM in clinical and investigative studies.

Noninvasive measurement of central vascular pressures with arterial tonometry: clinical revival of the pulse pressure waveform?

The arterial pulse has historically been an essential source of information in the clinical assessment of health. With current sphygmomanometric and oscillometric devices, only the peak and trough of the peripheral arterial pulse waveform are clinically used. Several limitations exist with peripheral blood pressure. First, central aortic pressure is a better predictor of cardiovascular outcome than peripheral pressure. Second, peripherally obtained blood pressure does not accurately reflect central pressure because of pressure amplification. Lastly, antihypertensive medications have differing effects on central pressures despite similar reductions in brachial blood pressure. Applanation tonometry can overcome the limitations of peripheral pressure by determining the shape of the aortic waveform from the radial artery. Waveform analysis not only indicates central systolic and diastolic pressure but also determines the influence of pulse wave reflection on the central pressure waveform. It can serve as a useful adjunct to brachial blood pressure measurements in initiating and monitoring hypertensive treatment, in observing the hemodynamic effects of atherosclerotic risk factors, and in predicting cardiovascular outcomes and events. Radial artery applanation tonometry is a noninvasive, reproducible, and affordable technology that can be used in conjunction with peripherally obtained blood pressure to guide patient management. Keywords for the PubMed search were applanation tonometry, radial artery, central pressure, cardiovascular risk, blood pressure, and arterial pulse. Articles published from January 1, 1995, to July 1, 2009, were included in the review if they measured central pressure using radial artery applanation tonometry.

In vivo murine left ventricular pressure-volume relations by miniaturized conductance micromanometry

The mouse is the species of choice for creating genetically engineered models of human disease. To study detailed systolic and diastolic left ventricular (LV) chamber mechanics in mice in vivo, we developed a miniaturized conductance-manometer system. alpha-Chloralose-urethan-anesthetized animals were instrumented with a two-electrode pressure-volume catheter advanced via the LV apex to the aortic root. Custom electronics provided time-varying conductances related to cavity volume. Baseline hemodynamics were similar to values in conscious animals: 634 +/- 14 beats/min, 112 +/- 4 mmHg, 5.3 +/- 0.8 mmHg, and 11,777 +/- 732 mmHg/s for heart rate, end-systolic and end-diastolic pressures, and maximum first derivative of ventricular pressure with respect to time (dP/dtmax), respectively. Catheter stroke volume during preload reduction by inferior vena caval occlusion correlated with that by ultrasound aortic flow probe (r2 = 0.98). This maneuver yielded end-systolic elastances of 79 +/- 21 mmHg/microliter, preload-recruitable stroke work of 82 +/- 5.6 mmHg, and slope of dP/dtmax-end-diastolic volume relation of 699 +/- 100 mmHg.s-1.microliter-1, and these relations varied predictably with acute inotropic interventions. The control normalized time-varying elastance curve was similar to human data, further supporting comparable chamber mechanics between species. This novel approach should greatly help assess cardiovascular function in the blood-perfused murine heart.

Assessment of endothelial function using digital pulse amplitude tonometry

The importance of endothelial dysfunction in the development and clinical expression of cardiovascular disease is well recognized. Impaired endothelial function has been associated with an increased risk of cardiovascular events. Endothelial function may be evaluated in humans by assessing vasodilation in response to stimuli known to induce the release of nitric oxide. A novel pulse amplitude tonometry device noninvasively measures vasodilator function in the microcirculation of the finger. This article reviews the recent studies that support the utility of digital pulse amplitude tonometry as a relevant test of peripheral endothelial function.

Using a wrist-worn device based on peripheral arterial tonometry to diagnose obstructive sleep apnea: in-laboratory and ambulatory validation

STUDY OBJECTIVES

To assess the accuracy of a wrist-worn device (Watch_PAT 100) to diagnose obstructive sleep apnea in the home.

DESIGN

Participants completed 2 overnight diagnostic studies with the test device: 1 night in the laboratory with concurrent polysomnography and 1 night in the home with only the Watch_PAT. The order of the laboratory and home study nights was random. The frequency of respiratory events on the PSG was quantified using indexes based on 2 definitions of hypopnea: the respiratory disturbance index (RDI) using American Academy of Sleep Medicine Task Force criteria for clinical research, also referred to as the Chicago criteria (RDI.C), and the Medicare guidelines (RDI.M). The Watch_PAT RDI (PAT RDI) and oxygen desaturation index (PAT ODI) were then evaluated against the polysomnography RDI.C and RDI.M, respectively, for both Watch_PAT diagnostic nights, yielding IN-LAB and HOME-LAB comparisons.

SETTING

Sleep laboratory affiliated with a tertiary-care academic medical center.

PATIENTS

30 patients referred with suspected OSA.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

The polysomnography and PAT measures were compared using the mean [2 SD] of the differences and the intra-class correlation coefficient (ICC). The receiver-operator characteristic curve was used to assess optimum sensitivity and specificity and calculate likelihood ratios. For the IN-LAB comparison, there was high concordance between RDI.C and PAT RDI (ICC = 0.88, mean difference 2.5 [18.9] events per hour); RDI.M and PAT ODI (ICC = 0.95, mean difference 1.4 [12.9] events per hour; and sleep time (ICC = 0.70, mean difference 7.0 [93.1] minutes) between the test device and PSG. For the HOME-LAB comparison, there was good concordance between RDI.C and PAT RDI (ICC = 0.72, mean difference 1.4 [30.1] events per hour) and RDI.M and PAT ODI (ICC = 0.80, mean difference 1.6 [26.4] events per hour) for the test device and PSG. Home studies were performed with no technical failures.

CONCLUSIONS

In a population of patients suspected of having obstructive sleep apnea, the Watch_PAT can quantify an ODI that compares very well with Medicare criteria for defining respiratory events and an RDI that compares favorably with Chicago criteria for defining respiratory events. The device can be used with a low failure rate for single use in the lab and home for self-administered testing.

Determination of intra-abdominal pressure using a transurethral bladder catheter: clinical validation of the technique

The determination of intra-abdominal pressures (IAP) may be useful in many clinical situations. The authors recently demonstrated in the canine model a close correlation between actual IAP and the bladder pressure measurements obtained from a transurethral catheter. The purpose of this study was to clinically validate this technique. The authors studied 16 patients, and compared IAP in three positions (supine, with compressions, and semi-erect) utilizing both direct intraperitoneal pressure monitoring and the pressure obtained with a transurethral bladder catheter. Their results demonstrated a linear relationship between the two methods described, with a mean r value of 0.95 in the supine and semi-erect positions, and 0.99 with abdominal compressions (P less than 0.0001). The authors conclude that transurethral monitoring of bladder pressure offers a safe, simple, and highly accurate method for evaluating IAP at the bedside. Studies evaluating the indication for its use in the operating room and intensive care settings appear warranted.

Sphincter of Oddi manometry: decreased risk of clinical pancreatitis with use of a modified aspirating catheter

This study was undertaken to determine whether routine use of a modified triple-lumen five French sphincter of Oddi manometry catheter would reduce the frequency and severity of post-manometry pancreatitis and pancreatic enzyme elevation. Seventy-six patients were alternately assigned to undergo sphincter of Oddi manometry (SOM) with a standard perfusion (infused group) catheter or the newly developed aspiration (aspirated group) catheter. After SOM, there were significantly more patients in the infused group with both amylase and lipase values elevated at least two times the upper limits of normal at 2 (p less than 0.001), 6 (p = 0.01), and 18 hours (p = 0.03) after the procedure. As compared with the standard perfusion system, the aspiration catheter was associated with a decreased frequency of clinical pancreatitis (23.5% vs. 3%, p = 0.01) reduced hospital stay (5 +/- 1.83 days, mean +/- SE, versus 1 day; p = 0.03) and milder pancreatitis. The aspiration manometry catheter should be considered for standard use for SOM, particularly if the pancreatic duct sphincter is being evaluated.