Total Monitoring Period Research Articles

Effect of tillage on sediment and phosphorus losses from a field and a catchment in south eastern Norway

Erosion and loss of soil is a large problem for water quality all over the world. Mitigation measures need to target the main sources of erosion at the right scale. For many areas there is still great uncertainty at the catchment level as to what are the main sources of erosion and how they can be managed. The objective of this article was to investigate the effect of tillage on soil losses at the field and catchment scale. Long-term monitoring data (20 years) from a catchment and a nested field site in the south eastern Norway were used. Results from the Vandsemb field showed that soil losses were on average 940 kg ha−1 yr−1 for years (n=5) when the field was autumn ploughed and 174 kg ha−1 yr−1 for years (n=8) when the field was not tilled in autumn. For the total monitoring period, surface soil losses were 330 kg ha−1 yr−1, whereas sub-surface soil losses were 130 kg ha−1 yr−1. Total phosphorus and dissolved reactive phosphorus (DRP) losses in surface runoff were 460 g ha−1 yr−1 and 150 g ha−1 yr−1, respectively and in sub-surface runoff they were 530 g ha−1 yr−1 and 270 g ha−1 yr−1, respectively. At the catchment scale, no relationship was found between the soil tillage on agricultural fields and the variation in losses of suspended sediments (SS) at the catchment scale. The average losses at Mørdre were for suspended sediments 2140 kg ha−1yr−1, for total phosphorus 2320 g ha−1 yr−1, and for DRP 240 g ha−1 yr−1. Weather conditions, especially during winter, were important for the temporal variation in losses of SS at both sites. Soil losses from the Mørdre catchment were approximately five times higher than from the Vandsemb field. The study findings suggest that changes in soil tillage were not the dominating cause of variations in loss of SS from the catchment, although these changes were important at the field scale.

Evaluation of Bayesian Estimation of a Hidden Continuous-Time Markov Chain Model with Application to Threshold Violation in Water-Quality Indicators

Natural resource managers require information concerning the frequency, duration, and long-term probability of occurrence of water-quality indicator (WQI) violations of defined thresholds. The timing of these threshold crossings often is hidden from the observer, who is restricted to relatively infrequent observations. Here, a model for the hidden process is linked with a model for the observations, and the parameters describing duration, return period, and long-term probability of occurrence are estimated using Bayesian methods. A simulation experiment is performed to evaluate the approach under scenarios based on the equivalent of a total monitoring period of 5-30 years and an observation frequency of 1-50 observations per year. Given constant threshold crossing rate, accuracy and precision of parameter estimates increased with longer total monitoring period and more-frequent observations. Given fixed monitoring period and observation frequency, accuracy and precision of parameter estimates increased with longer times between threshold crossings. For most cases where the long-term probability of being in violation is greater than 0.10, it was determined that at least 600 observations are needed to achieve precise estimates. An application of the approach is presented using 22 years of quasi-weekly observations of acid-neutralizing capacity from Deep Run, a stream in Shenandoah National Park, Virginia. The time series also was sub-sampled to simulate monthly and semi-monthly sampling protocols. Estimates of the long-term probability of violation were unbiased despite sampling frequency; however, the expected duration and return period were over-estimated using the sub-sampled time series with respect to the full quasi-weekly time series.

To roam or to home: site fidelity in a tropical coastal shark

Understanding patterns in site fidelity is important for defining the ecological role of species in the systems they use and for gauging the effects of human impacts on their populations. We analyzed long-term movement data of adult spottail sharks (Carcharhinus sorrah) in Cleveland Bay, Australia, to define the degree of site fidelity this species shows to coastal areas. Individuals were monitored in the study site for 28–566 days, and residency index (i.e., proportion of days present to total monitoring period) ranged from 0.08 to 0.95. Using a randomization procedure, we determined that the movement paths for 90 % of individuals (11 female and 7 male) were more constrained than random, with individuals exhibiting a high degree of site fidelity to consistent areas within the study site. Examining distances moved revealed that individuals used the same areas repeatedly and remained in close proximity (i.e., <6 km) to their location of first detection. While some individuals consistently used and returned back to the same locations, low residency among others suggests that a portion of the population may roam more widely. Long-term site fidelity to consistent areas may be a successful behavioral strategy for C. sorrah by increasing individual fitness through spatial familiarity and knowledge of resources.

The Significance of Transcutaneous Continuous Overnight CO2Monitoring in Determining Initial Mechanical Ventilator Application for Patients with Neuromuscular Disease

ObjectiveTo reveal the significance of continuous transcutaneous carbon dioxide (CO2) level monitoring through reviewing cases which showed a discrepancy in CO2 levels between arterial blood gas analysis (ABGA) and continuous transcutaneous blood gas monitoring.MethodMedical record review was conducted retrospectively of patients with neuromuscular diseases who had started home mechanical ventilation between June 2008 and May 2010. The 89 patients underwent ABGA at the 1st hospital day, and changes to their CO2 level were continuously monitored overnight with a transcutaneous blood gas analysis device. The number of patients who initially appeared to show normal PaCO2 through ABGA, yet displayed hypercapnea through overnight continuous monitoring, was counted.Results36 patients (40.45%) presented inconsistent CO2 level results between ABGA and continuous overnight monitoring. The mean CO2 level of the 36 patients using ABGA was 37.23±5.11 mmHg. However, the maximum and mean CO2 levels from the continuous monitoring device were 52.25±6.87 mmHg and 46.16±6.08 mmHg, respectively. From the total monitoring period (357.28±150.12 minutes), CO2 retention over 45 mmHg was detected in 198.97 minutes (55.69%).ConclusionAlthough ABGA only reflects ventilatory status at the puncturing moment, ABGA results are commonly used to monitor ventilatory status in most clinical settings. In order to decide the starting point of home mechanical ventilation in neuromuscular patients, continuous overnight monitoring should be considered to assess latent CO2 retention.

Cerebral extracellular chemistry and outcome following traumatic brain injury: a microdialysis study of 223 patients.

Secondary insults can adversely influence outcome following severe traumatic brain injury. Monitoring of cerebral extracellular chemistry with microdialysis has the potential for early detection of metabolic derangements associated with such events. The objective of this study was to determine the relationship between the fundamental biochemical markers and neurological outcome in a large cohort of patients with traumatic brain injury. Prospectively collected observational neuromonitoring data from 223 patients were analysed. Monitoring modalities included digitally recorded intracranial pressure, cerebral perfusion pressure, cerebrovascular pressure reactivity index and microdialysis markers glucose, lactate, pyruvate, glutamate, glycerol and the lactate/pyruvate ratio. Outcome was assessed using the Glasgow Outcome Scale at 6 months post-injury. Patient-averaged values of parameters were used in statistical analysis, which included univariate non-parametric methods and multivariate logistic regression. Monitoring with microdialysis commenced on median (interquartile range) Day 1 (1-2) from injury and median (interquartile range) duration of monitoring was 4 (2-7) days. Averaged over the total monitoring period levels of glutamate (P = 0.048), lactate/pyruvate ratio (P = 0.044), intracranial pressure (P = 0.006) and cerebrovascular pressure reactivity index (P = 0.01) were significantly higher in patients who died. During the initial 72 h of monitoring, median glycerol levels were also higher in the mortality group (P = 0.014) and median lactate/pyruvate ratio (P = 0.026) and lactate (P = 0.033) levels were significantly lower in patients with favourable outcome. In a multivariate logistic regression model (P < 0.0001), which employed data averaged over the whole monitoring period, significant independent positive predictors of mortality were glucose (P = 0.024), lactate/pyruvate ratio (P = 0.016), intracranial pressure (P = 0.029), cerebrovascular pressure reactivity index (P = 0.036) and age (P = 0.003), while pyruvate was a significant independent negative predictor of mortality (P = 0.004). The results of this study suggest that extracellular metabolic markers are independently associated with outcome following traumatic brain injury. Whether treatment-related improvement in biochemistry translates into better outcome remains to be established.

Comparison of Reflux Frequency During Prolonged Multichannel Intraluminal Impedance and pH Monitoring On and Off Acid Suppression Therapy

The aim of this study was to assess and compare reflux frequency during prolonged multichannel intraluminal impedance and pH monitoring with special attention to the 2-hour postprandial interval after the major meal in patients on or off proton pump inhibitor (PPI) therapy. We retrospectively analyzed multichannel intraluminal impedance and pH studies performed in 110 patients monitored on (n=70) or off PPI (n=40) to assess number of acid and nonacid reflux episodes per hour (RE/h). Patients on PPI had significantly higher mean number of nonacid than acid RE/h during the total monitoring and 2-hour postprandially (pp). The mean number of nonacid RE/h was significantly higher during 2-hour pp than the total monitoring period (4.5 vs. 1.7). Patients off PPI had significantly higher mean number of acid than nonacid RE/h only during the total monitoring. The total number of RE/h was significantly higher during 2-hour pp than the total monitoring (5.1 vs. 2.3). Patients on PPI had significantly higher mean number of nonacid RE/h whereas patients off PPI had significantly higher mean number of acid RE/h throughout total monitoring and 2-hour pp. Number of RE/h was numerically (2.3 vs. 1.7) but not statistically greater off PPI than on PPI during total monitoring. The total number of reflux episodes increases during the postprandial period irrespective of PPI therapy. Maximal rate of reflux episodes occurs during the postprandial period and is the same whether taking PPI or not.

Monitoring temperatures in the vaccine cold chain in Bolivia

This study monitored vaccine cold chain temperatures during routine DTP-HB-Hib vaccine shipments from central stores to 11 communities in 3 provinces of Bolivia. In all 11 monitored shipments, vaccines were exposed to freezing temperatures at one or more points. In each of the shipments, temperatures below 0 °C were recorded for 2–50% of the monitoring period. Freezing occurred at almost every level of the cold chain distribution system, especially during district and health center storage and during transport to the province and district levels. Seven of the 11 shipments were exposed to temperatures above 8 °C, although none were exposed to excessive heat longer than 1.3% of the total monitoring period.

Predictive value of initial computerized tomography scan, intracranial pressure, and state of autoregulation in patients with traumatic brain injury

The authors explored the relationship between computerized tomography (CT) scan findings and intracranial pressure (ICP) measurements obtained in the first 24 hours of monitoring to identify parameters predicting outcome in patients with severe traumatic brain injury (TBI). Intracranial pressure, mean arterial blood pressure, cerebral perfusion pressure (CPP), and pressure reactivity index were measured continuously in 126 patients with severe TBI who were admitted to a neuroscience critical care unit. Mean values in the initial 24 hours of monitoring and in the total period of monitoring were compared with types of injury categorized on the basis of the initial CT scan according to the classification of Marshall, et al., and with Glasgow Outcome Scale scores. The initial CT scan classification correlated significantly but weakly with ICP measured during the first 24 hours of monitoring (p = 0.036) but not with mean ICP over the total time of intensive care. Both midline shift and the ratio of frontal horn diameter to internal diameter correlated with ICP in the first 24 hours (p < 0.007) and with ICP over the total monitoring period (p < 0.03). Outcome score correlated with initial CT scan findings (p = 0.018), ICP over the total monitoring period (p < 0.0023), pressure reactivity over the total monitoring period (p < 0.0002), and pressure reactivity in the first 24 hours (p < 0.0001) but not with ICP in the first 24 hours. Patients with disturbed pressure reactivity in the first 24 hours after injury had a significantly higher mortality rate than patients with intact pressure reactivity (28.6% compared with 9.5%; p < 0.001). Patients with severe TBI who have early loss of autoregulation have a worse prognosis. Mean ICP values in patients with diffuse TBI cannot be predicted by using the Marshall CT scan classification.

Ethnicity and gender related differences in extended intraesophageal pH monitoring parameters in infants: a retrospective study

BackgroundGastroesophageal reflux disease (GERD) is believed to be more common in adult males as compared to females. It also has been shown in adults to be more common in Caucasians. We wanted to determine ethnicity and gender related differences for extended pH monitoring parameters in infancy.MethodsExtended pH monitoring data (EPM) from infants <1 year of age were reviewed. Results were classified in two groups, as control and Gastroesophageal reflux disease (GERD) group based on the reflux index (RI). The GERD group had RI of equal to or more than 5% of total monitoring period. The parameters of RI, total number of episodes of pH < 4, and the number of episodes with pH < 4 lasting more than 5 minutes were compared by genders and by ethnic groups, Caucasians and African American (AA).ResultsThere were 569 infants, 388 controls, 181 with GERD (320 males, 249 females; 165 Caucasians, 375 AA). No statistical difference in EPM parameters was detected between genders in both groups. However, Caucasian infants had a significantly higher incidence of GERD than AA infants (p = 0.036). On stratifying by gender, Caucasian females had a significantly higher number of reflux episodes >5 minutes as compared to AA females in the control group (p = 0.05). Furthermore, Caucasian females with GERD showed an overall higher trend for all parameters. Caucasian males had a trend for higher mean number of reflux episodes as compared to AA males in the control group (p = 0.09).ConclusionAlthough gender specific control data do not appear warranted in infants undergoing EPM, ethnic differences related to an overall increased incidence of pathologic GERD in Caucasian infants should be noted.

Extended (48 hr) Monitoring in Patients with Extra-esophageal Manifestations of GERD

Introduction: The evaluation of patients with extra-esophageal manifestations of gastro-esophageal reflux (GERD) frequently requires pH testing. The recent development of a tubeless radio-telemetry system allows for monitoring of esophageal pH for more than 24-hours. Whether this extended period of evaluation affords an expanded diagnostic confidence in this population has not been determined. Methods: Consecutive patients referred for tubeless ambulatory pH testing for evaluation of suspected extra-esophageal GERD over a 9-month period were included in the study. The monitoring device was attached to the esophagus 6 cm above the squamo-columnar junction after endoscopic localization. The total % esophageal acid exposure was evaluated in the first 24 hours, second 24 hours and for the total 48 hours of the study. Studies were considered normal if the total esophageal acid exposure was below the published upper limits of normal (5.33%) for the total monitoring period and each of the two 24 hour sub-periods. Likewise, a study was considered abnormal if all of the period's acid exposures were above 5.33%. Studies were considered discordant when one of the study periods was normal and the other abnormal. Patients referred to evaluate the efficacy of acid suppressive therapy (medications or surgery) were also included in this study. Results: During the study period 115 patients were evaluated for suspected GERD. 36 for typical GERD (excluded from subsequent analysis) and 79 for extra-esophageal GERD (chest pain 45, pulmonary 21, ENT 13). Three patients were excluded due to failure to capture data in the second 24 hrs. The data in the remaining 76 patients are shown in the table. Of the patients with discordant results 8 were positive on day 1 and negative on day 2 and 6 negative on day 1 and positive on day 2. In these patients the composite 48-hour exposure was abnormal in 7. In patients studied to evaluate acid control (13 on double-dose PPI, one after Nissen fundoplication), 12 (85.7%) had good acid suppression in all three study periods. All patients completed the study satisfactorily and no major side-effects were observed. Summary: Extended evaluation beyond 24 hours increases the diagnostic yield of pH testing and should improve the sensitivity of ambulatory pH monitoring. This test also provides valuable information in the assessment of acid suppression therapies.

Higher systemic arterial pressures are rarely associated with cerebral perfusion pressure deterioration in brain injury

Background A computerized monitoring system was developed and utilized to evaluate the relationship between mean arterial pressure and intracranial pressure and its effect on cerebral perfusion pressure to determine how best to maximize cerebral perfusion pressure. Methods The monitoring system recorded mean arterial pressure and intracranial pressure, the values of which were used to calculate cerebral perfusion pressure. We developed the program for and utilized a “moving window” regression analysis to divide the total monitoring period into 2-hour overlapping epochs. The relationship between mean arterial pressure and intracranial pressure was then analyzed in each 2-hour epoch and classified into Types A, B, C, and D epochs, each with clinical significance. Type A epochs involved intracranial pressure increasing more than mean arterial pressure and resulted in deterioration of cerebral perfusion pressure. Type B epochs involved mean arterial pressure increasing more than intracranial pressure and resulted in an increase of perfusion pressure. Type C epochs involved mean arterial pressure increasing and intracranial pressure decreasing and also resulted in an increase in perfusion pressure. Type D epochs had no statistically significant relationship between mean arterial pressure and intracranial pressure. Results Forty-five patients with various pathologies were studied. The majority ( n = 35) were patients with severe brain injury. Of 5,694 total hours monitored and 22,776 total epochs analyzed, 1.5% epochs were Type A, 5.9% were Type B, 2.1% were Type C, and 90.5% were Type D. Conclusion In most patients, most of the time, increasing mean arterial pressure did not worsen cerebral perfusion pressure.

Noise distribution of an incubator with nebulizer at a neonatal intensive care unit in southern Taiwan.

The purpose of this study was to investigate the noise distribution and sources of peak noise inside an incubator with a nebulizer at a neonatal intensive care unit of a medical center in Southern Taiwan. Sound levels were monitored continuously with an electronic sound-meter for 24 hours daily over a one-week period. Three working hours (day, evening, and night hours) in the weekday and weekend (total 48 hours) were selected randomly from the one-week period of noise survey to observe peak noise at levels > or = 65 dBA. Results revealed that 24.8% of the total monitoring period had sound levels at < or = 59 dBA, 58.9% at 60-64 dBA, 10.7% at 65-69 dBA, and 5.6% at > or = 70 dBA. Furthermore, a total of 947 peak noises > or = 65 dBA were found within the 48 hours, of which 61.5% were in a range of 65-69 dBA, 24% of 70-74 dBA, 9.8% of 75-79 dBA, and 4.8% > or = 80 dBA. Human-related sources, equaling 79%, were the dominant peak noises. These noises included opening and closing doors, banging the incubator hood, conversation among staff, nursing activity inside the incubator, tearing and opening paper or bags, opening and closing trash can lids, and bumping metal carts or other apparatus. Nonhuman-related sources were 21% including alarms of monitors and running of the incubator motor. Results of this study showed that the noise distribution in the incubator with nebulizer was far above a protective limitation of 58 dBA, suggested by the American Academy of Pediatrics in 1974. However, most peak noises could be reduced by modification of staff behavior. Therefore, determinations of noise distribution and sources of peak noise in this study are useful for further noise reduction programs.

Patterns of Change in the Electrocardiogram after Halofantrine Treatment of Acute Uncomplicated Falciparum Malaria in Children

Objective: To examine the cardiac effects of halofantrine by evaluating the apatterns of change in the ECG, including the PR and QTC intervals and the presence or absence of rhythm disturbances, following treatment with halofantrine of children with acute, symptomatic, uncomplicated falciparum malaria. Design and Setting: This was an observational study performed in Nigeria in 1994 to 1995 and in 1997. Patients and Participants: 63 children who were enrolled in studies on the antimalarial efficacy of halofantrine. Methods: A 12-lead ECG was recorded before and at specific intervals after administration of halofantrine (24 mg/kg of bodyweight) for a total monitoring period of 1 to 2 weeks. Changes in the ECG intervals and the patterns of change were analysed using defined criteria. Results: There was no clinical cardiac intolerance to halofantrine. 76% of the children (48 of 63) showed changes in their ECG. There was a significant increase in PR interval only at 8 hours after treatment. The rate-corrected QT (QTC) interval increased following treatment, with significant differences from time zero from 6 or 8 to 96 hours. A grouping of the patterns of the ECG change based on the type of interval prolongation, the relationship to the time-course of therapy or drug administration, the duration of prolongation and the absence or presence of rhythm disturbance showed the following patterns: no change (24%), early or late monophasic prolongation of PR interval (3%), early monophasic (60%) or late monophasic (1.5%) prolongation of QTC interval, biphasic prolongation of QTC interval (4.7%), early monophasic prolongation of both PR and QTC intervals (1.5%), biphasic prolongation of both PR and QTC intervals (1.5%), other patterns (3%). Conclusion: Halofantrine has significant effects on ECG intervals with varying patterns of change; the biphasic and late monophasic changes suggest that adverse cardiac effects may be early, early and late, or late in appearing. In children, the currently recommended dose of halofantrine for the treatment of malaria may produce serious cardiac effects.

Survival of Dicor glass-ceramic dental restorations over 14 years. Part II: Effect of thickness of Dicor material and design of tooth preparation

Statement of problem. The influence of different restorative design features on the long-term survival of Dicor glass-ceramic restorations is not well understood. Purpose. This study examined the relationship of different types of restorations and methods of preparation with the survival of Dicor glass-ceramic restorations functioning in vivo. Material and methods. A total of 1444 Dicor glass-ceramic restorations were placed on the teeth of 417 adults. Failure was defined as a restoration that required remake because of material fracture. Survival of restorations of different types and with different methods of preparation was described by using Kaplan Meier survivor functions. Statistical significance between restoration type and preparation method was determined with the log rank test. Results. Probability of survival of a typical partial coverage restoration was 92% at 11.3 years. There was no statistically significant difference between the survival of inlay or onlay restorations. For the 91 cores used for pulpless teeth, none failed over a total cumulative monitoring period of 419 years. There was no significant difference in survival of acid-etched Dicor restorations that were placed on shoulder or chamfer preparations. Thickness measured at the midpoint of the labial, lingual, mesial, distal, and midocclusal surfaces did not relate to risk of failure. Conclusions. The majority of Dicor glass-ceramic partial coverage inlay and onlay restorations and cores survived over time. Survival of restorations with either chamfer or shoulder preparations did not differ whether the restoration was acid-etched. Thickness of the restoration measured at the midaxial point of each surface did not relate to survival. (J Prosthet Dent 1999;81:662-7.)

Analysis of Home Monitoring Beyond 75 Weeks Post-conceptual Age. 652

Objective: To determine the need for home monitoring (HM) for apnea of infancy (AI) beyond 75 weeks post-conceptual age (PCA). HM is often prescribed for AI; however, when AI persists into late infancy, it is often difficult to determine when to discontinue HM. Through a retrospective review of our university-based infant apnea program, 122 infants (total of 1200 infants monitored) were identified who were treated with HM beyond 75 weeks PCA for the period of December, 1990 through December, 1995. Gestational age was 36.9± 4 weeks (SEM), and total monitoring period was 288.6± 10.7 days (SEM). Patients were followed with regular phone contact for the duration of monitoring, and respiratory pattern was determined by impedance pneumocardiogram, event recording monitor (1992 and beyond,) or both, prior to monitor discontinuation. We observed that none of the infants that were asymptomatic at 75 weeks PCA had subsequent episodes of ALTE or SIDS, despite the fact that many had persistent abnormalities on sleep studies. In addition, there was a trend towards poor compliance late in infancy. This data suggests that in asymptomatic infants, it may be appropriate to consider discontinuation of home monitoring by 75 weeks PCA despite persistent abnormalities on sleep studies. At an average monthly charge in Philadelphia of $400.00 for an event recording monitor, continued use beyond 75 weeks PCA does not appear to be cost-effective in this population.

An Occupational Noise Exposure Assessment for Headset-Wearing Communications Workers

Abstract An occupational noise exposure study was conducted on a group of 37 communications workers who wear closed-back circumaural headsets. These workers underwent preevaluation audiometric testing, and were monitored for noise exposure during a normal work shift. The noise exposure was assessed employing a real ear model, in which subminiature microphones are placed at the entrance of the external auditory meatus of each subject. The total monitoring period for each subject was subdivided into several cycles. The data from the cycles were compared and incorporated into an average equivalent continuous sound level for each subject. Resulting equivalent continuous sound levels ranged from 79.9 to 103.7 dBA, with a mean value of 87.0 dBA. The maximum peak values ranged from 119.2 to 148.8 dB, with a mean of 140.8 dB. Equivalent continuous sound levels and peak sound levels were compared with the gender, age, work experience, and smoking status of each subject. Comparison of noise exposure level with demo...

Sampling Bias in Respirometry

Comparisons of the metabolic rates of species, populations, and treatment groups of animals are common. However, the data used in these comparisons may not be truly equivalent. We report the effects of varying (1) total time from which minimum metabolism is selected and (2) time over which metabolic rate is calculated (calculation interval) on estimates of oxygen consumption for Microtus agrestis and Apodemus sylvaticus. Oxygen consumption was measured at 10°, 20°, and 30° C, using open-circuit respirometry. The lowest 15 min of metabolism were 13% and 65% higher for Microtus and Apodemus, respectively, when selected from a total monitoring period of 30 min than when selected from a period of 6 h. This demonstrates the importance of standardizing the duration of time from which minimal estimates of metabolism are selected (i. e., the amount of time for which metabolism is measured). For Microtus, minimum oxygen consumption was 12% higher when calculated over 60 min than when calculated over 15 min. We sug...

Measurement of right atrial oxygen saturation by fiberoptic oximetry accurately reflects mixed venous oxygen saturation in swine.

Continuous fiberoptic measurement of mixed venous oxygen saturation (SvO2) via a pulmonary artery catheter is a useful, though invasive, monitoring technique. Continuous right atrial venous oxygen saturation measurement by oximetry offers the potential of a significantly less invasive SvO2 measurement. However, catheter motion, character of the vessel, chamber wall reflection, the filtering technique involved in calculating oxygen saturation, and the streaming of venous blood prior to ventricular mixing may influence the feasibility of continuous right atrial (RA) SvO2 measurement. This study investigated the performance of fiberoptically measured RA SvO2, at a position 2 cm from the tricuspid valve, relative to simultaneously measured pulmonary artery (PA) SvO2. Ten pigs were subjected to circulatory shock or chemically induced lung damage. Over a total monitoring period of approximately 40 hours, 464 paired data points were sampled at 5-minute intervals. The difference between the overall means of RA and PA SvO2 was 0.91% with a standard error of the estimate of 4.7%, a regression equation of RA SvO2 = PA SvO2 (0.94 + 2.1) PA So2, and a correlation coefficient of 0.94. Our conclusion, although extrapolated from a pig model, is that fiberoptic SvO2 monitoring may be accomplished less invasively and at a lower cost with a right atrial catheter.