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Biomedical subjects

K G Rosén

Publications and source records attributed to K G Rosén.

At least 19 recordsLinked to original sources
PubMed2005

Electrocardiographic changes following umbilical cord occlusion in the midgestation fetal sheep.

BACKGROUND: Clinical studies show that analysis of the fetal electrocardiographic (FECG) ST waveform at term gives important information on the myocardial response to intrapartum asphyxia. However, it is not known whether the preterm fetus responds in a similar fashion. The objective of the present study was to evaluate the FECGST response to umbilical cord occlusion in the preterm fetal sheep. METHODS: Fetal sheep at midgestation were subjected to 25 min umbilical cord occlusion (n = 7) and compared to controls (n = 5). Changes in the FECGST waveform were recorded together with arterial blood pressure, heart rate, and acid base status during the occlusion and for 3 days afterward. RESULTS: Umbilical cord occlusion resulted in immediate bradycardia (control: 187 +/- 7 bpm versus occlusion: 102 +/- 7 bpm), hypertension (control: 43.2 +/- 1.1 mmHg versus occlusion: 59.8 +/- 2.2 mmHg), and an initial increase in the T/QRS ratio (control: 0.10 +/- 0.02 versus occlusion: 0.60 +/- 0.10, P < 0.001), followed by hypotension (21.7 +/- 1.2 mmHg), normalization of the T/QRS ratio, and in some cases the development of negative T waves toward the end of the occlusion. CONCLUSIONS: These studies show that the midgestation fetal sheep has the capacity to react to umbilical cord occlusion with a significant increase in the amplitude of the ST waveform together with an augmentation of blood pressure, which then subsides as the occlusion continues. The appearance of negative ST segment appears to signify significant cardiac dysfunction. The characteristic progression of ST-waveform changes in response to umbilical cord occlusion in midgestation fetal sheep, suggests that monitoring the ST waveform may contribute clinically important information also in the preterm individual.

Animals↗
PubMed2002

ST analysis of the fetal electrocardiogram during labor: Nordic observational multicenter study.

OBJECTIVE: To assess the diagnostic power of cardiotocography (CTG) plus the ST interval of the electrocardiogram (ECG) clinical guidelines with combined fetal heart rate and ST waveform analysis of the fetal ECG recorded during labor, to identify an adverse labor outcome (neonatal neurological symptoms and/or metabolic acidosis). STUDY DESIGN: An observational, multicenter study was undertaken in 12 Nordic labor wards. A total of 573 women in labor were monitored using a prototype of the STAN S 21 recorder with fetal ECG data and computerized ST analysis. RESULTS: Fifteen cases of intrapartum fetal hypoxia identified from neurological neonatal symptoms and/or cord artery pH < 7.05 with base deficit in extracellular fluid > 12.0 mmol/l were recorded. All these cases were identified by CTG + ST clinical guidelines. Five developed neonatal symptoms and had ECG abnormalities during the first stage of labor and, of the remaining ten, eight showed ST changes during active pushing in the second stage. Another eight cases had acidemia only and normal neonatal outcome. Seven of these displayed CTG + ST abnormalities. The high sensitivity of CTG + ST to predict fetal acidosis was associated with a marked increase in positive predictive values compared with conventional CTG. CONCLUSION: The STAN clinical guidelines identify fetuses at risk of intrapartum asphyxia.

Acidosis↗
PubMed2001

Reduction of fine airborne particulates (PM3) in a small city centre office, by altering electrostatic forces.

A two stage intervention study was carried out to establish the degree to which a newly developed, electrostatic air cleaning (EAC) system can improve indoor air quality (IAQ) by reducing the number of airborne fine particles. The IAQ and how employees in a city centre office (49 m2) perceived it, was monitored from May until November 1998. The number of fine particles, PM3 (0.3-3.0 microm); number of coarse particles, PM7 (3.0-7.0 microm); number of small positive and negative air ions; relative humidity and temperature were recorded in and out of doors. To assess the employees' perception of any changes in their work environment, a questionnaire was completed. Number of particles, relative humidity and temperature were also recorded in a nearby office, equipped with an identical air processor, where no interventions were made. The results from the first intervention (Stage 1), comparing number of airborne particles outdoors to indoors, gave a 19% reduction for PM3 and a 67% reduction for PM7 (P < 0.001). The reduction in PM3 was inconsistent and not statistically significant (P = 0.3). The reduction in PM7 from outdoors and the removal of PM7 created indoors was achieved by optimizing the existing air moving equipment. The results from the second intervention (Stage 2--with EAC units installed) comparing indoor to outdoor values, gave a further reduction in PM3 of 21% (P < 0.001) and a further 3% reduction for PM7 (P > 0.05). Therefore, at the end of Stage 2, the total reductions in particles from outdoors to indoors were 40% for PM3 and 70% for PM7 (P < 0.001). The Stage 2 results strongly suggest that electrostatic forces, created by the EAC unit(s) improved the removal of PM3, with no further significant improvement in the reduction of PM7. The questionnaire indicated an improvement in the IAQ, as perceived by the employees. The results suggest that the EAC system is effective in reducing PM3 and thereby improving IAQ in an urban office.

Air Movements↗
PubMed2001

Fetal electrocardiogram waveform analysis in labour.

The fetal electrocardiogram recorded during labour has so far been used for heart rate recording only. Extensive experimental, bioengineering and clinical research for more than 25 years on changes in the morphology of the electrocardiogram have provided more detailed information on fetal reactions to the stress and strain of labour. ST waveform analysis has been shown to provide new parameters that have the ability to monitor intrapartum hypoxia, thereby not only reducing the risk of the baby being born with hypoxia, but also significantly reducing the number of operative interventions.

Acid-Base Imbalance↗
PubMed1999

Would removing indoor air particulates in children's environments reduce rate of absenteeism--a hypothesis.

To conduct a controlled trial to test the ability of a newly developed electrostatic air cleaning technology (EAC) to improve Indoor Air Quality (IAQ) as defined by levels of airborne particles and to investigate the potential to reduce non-attendance rates due to illness among children in two Swedish day care centres. The EAC technology was shown to significantly reduce the indoor particulate load for very fine particles caused by outdoor air pollution by 78% and to reduce the number of fine particles produced indoors by 45%. To test the hypothesis, non-attendance was followed in two centres during 3 years. The EAC technology was in operation during year 2. Non-attendance rates among children in the larger day-care centre decreased by 55%, equalling those levels noted in family-based day care. It is speculated that the air cleaning effect may be due to alterations in electrostatic forces operating within the room enabling fine particulate matter to more easily become and stay airborne. The EAC technology is cost-efficient and might be a way forward to improve IAQ.

Absenteeism↗
PubMed1999

European Community multi-Center Trial "Fetal ECG Analysis During Labor": ST plus CTG analysis.

This report form part of the European Community Multi-Center Trial "Fetal ECG Analysis during Labor". Aim of this prospective trial was to identify changes in the fetal ECG waveform with cases of verified fetal hypoxia. In this paper we also report on the use of a newly developed automatic system for identification of ST waveform changes (ST Log). All ECG were recorded with the STAN recorder (Neoventa Medical AB, Gothenburg, Sweden). The ECG information was not displayed during labor in order not to influence the clinical management. This report includes data from 320 cases and include six cases of fetal intrapartum hypoxia. Twenty seven cases showed changes in ST waveform. All five cases with the most marked ST change (a rise in T/QRS of > 0.10 units and lasting more then 10 minutes) had signs of ongoing intrapartum hypoxia. Six out of six cases with evidence of intrapartum asphyxia, showed ST changes. On the basis of our multi-center trial it appears that the combined analysis of CTG and ST waveform changes provides an accurate way to identify adverse events during labor. The work is continuing with a new STAN recorder developed by Neoventa Medical in Göteborg and currently being tested in a Swedish randomized, controlled multi-center trial.

Acid-Base Equilibrium↗
PubMed1997

European Community Multicentre Trial "Fetal ECG Analysis During Labour": the P-R interval.

The aim of the European Community Multicentre Trial on Fetal ECG Analysis During Labour was to collect a clinical database of electrocardiograms on which the different patterns of ST waveform and time interval changes, so far identified, could be studied. The aim of this paper was to study the PR-RR relationship and the P wave patterns during normal labour. One thousand three hundred fifty accelerations and 350 decelerations were analysed in 618 labours, all with normal fetal outcome. All ECGs were recorded with the STAN recorder and linked to a PC system for data acquisition and analysis. A positive relationship between P-R and R-R intervals was identified in all reactive fetal heart rate traces. A P-R shortening was identified also with all decelerations of more than 40 bpm from the baseline, resulting in a negative PR-RR relationship. Experimental works have described a P-R shortening concurrent with the maximal R-R lengthening during acutely induced hypoxemia in fetal lambs. In our study normal cord acid-base status indicated that the majority of bradycardia episodes recorded were not related to acute hypoxemia: PR-RR relationship changes seem therefore to indicate an intact physiological fetal heart adaptive response to rapid change in the environment of either hypoxemic or haemodynamic origin. A negative PR-RR relationship by itself seems to be nothing more than an indicator of decelerations during labour and seems unable to discriminate between decelerations of different origin. Finally the P wave was no longer detectable during decelerations of more than 800 msec: in this situation the P-R interval can not be reliably measured.

Electrocardiography↗
PubMed1994

The fetal electrocardiogram: ST waveform analysis during labour.

Intrapartum fetal surveillance is still under debate, despite 30 years of clinical experience and numerous clinical trials. Waveform analysis of the fetal electrocardiogram has emerged not as an alternative to cardiotochography but as a support tool to allow more accurate interpretation of intrapartum events. During hypoxia, the healthy fetus is utilizing a series of defense mechanisms. Among these, the increase in sympathetic activity, with an increase in circulating adrenaline, activates the myocardium with an increase in workload (the product of cardiac output, myocardium contractility and blood pressure). If there is an imbalance between myocardial oxygen supply and consumption, determined by the workload, then anaerobic metabolism, with a breakdown of myocardial glycogen stores starts and high T waves emerges. ST depression with negative T waves has recently been observed during hypoxia experiments in experimentally growth retarded guinea pigs whilst their normally grown littermates showed ST elevation. These findings have stimulated the development of a dedicated fetal ECG monitor - STAN - incorporating both standard CTG and ST waveform analysis. The STAN concept has now been taken through the process of recognized validation including several prospective studies and a large randomized trial in Plymouth of 2400 high risk, term deliveries. The T/QRS ratio is only one parameter to be used - equally important is to identify the occurrence of ST depression with biphasic negative T waves and to interrelate the CTG and the ST waveform as outlined in the clinical guidelines (table I). This table contains the clinical experience gained over many years and has formed the basis for the first randomized controlled trial comparing ST waveform + CTG with CTG only. Obviously, when the T/QRS ratio is used as the only component of such a scheme, confusion emerges. The analysis should also contain cases with significant intrapartum hypoxia. Recent findings indicate that only when cord artery pH falls below 7.0 and when there is substantial metabolic acidemia is there a significant risk of intrapartum asphyxia. Metabolic acidemia should be estimated from base deficit in the extracellular fluid and the combination of cord artery and vein data should allow for a more accurate assessment of intrapartum events, including the assessment of the duration of hypoxia. The Plymouth trial has tested the hypothesis that the combination of ST wave form and CTG analysis compared with CTG analysis only would reduce operative interventions for fetal distress without placing the fetus at a risk.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrocardiography↗
PubMed1992

Changes in the PR, RR intervals and ST waveform of the fetal lamb electrocardiogram with acute hypoxemia.

The PR and RR intervals and T wave amplitude of the fetal lamb electrocardiogram were studied during acute hypoxemia produced by reduction of the maternal placental blood flow. Five chronically-instrumented fetal lambs (124 to 143 days of gestation) were subjected to acute hypoxemia (observations = 13) through complete occlusion of the maternal aorta for 60 s. The fetuses responded to the occlusion with a fall in oxygen tension (2.18 +/- 0.12 kPa to 1.11 +/- 0.14 kPa, SEM, P < 0.001) and oxygen saturation (48 +/- 4% to 19 +/- 4%, P < 0.001). Modest changes of pH (7.37 +/- 0.05 to 7.35 +/- 0.01, p), carbon dioxide tension (5.79 +/- 0.15 kPa to 6.17 +/- 0.14 kPa, P < 0.001) and plasma lactate concentration (2.1 +/- 0.6 mmol/l to 2.2 +/- 0.6 mmol/l, ns) occurred. The PR interval showed a triphasic pattern following occlusion. Initially, and simultaneously with the onset of the RR interval lengthening, a prolongation of the PR interval occurred (P < 0.01) with a peak value after 41 +/- 3 s after occlusion. Following this transient prolongation, the PR interval shortened concurrently with a maximum lengthening of the RR interval (P < 0.001) 2 +/- 3 s after the end of the occlusion. A maximum PR shortening (P < 0.001) occurred 27 +/- 5 s after occlusion followed by a prolongation of the PR interval (P < 0.001) with a peak value 203 +/- 21 s after release of the occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

How to assess fetal metabolic acidosis from cord samples.

The degree of metabolic acidosis at birth has been calculated in cord artery and vein samples from 21 term fetuses with cord artery pH less than 7.20. The aim of the study was to compare base deficit values calculated from either Siggaard-Andersen alignment nomogram (BD blood) or the Acid-Base chart (BD extra cellular fluid, BDecf). BDblood was found to be consistently higher in the cord artery as compared with BDecf, 13.2 +/- 3.5 and 9.9 +/- 2.9 mmol/l (Mean +/- SD), respectively. A significant correlation was found between cord artery PCO2 and BDblood whereas BDecf appeared unaffected by PCO2. In cases with cord entanglement BDecf a-v differences were increased to 3.4 +/- 2.3 mmol/l as compared with the small a-v difference noted in acidotic cases without cord entanglement, 1.1 +/- 1.25 mmol/l. It is speculated that with acutely emerging, intermittent asphyxia due to cord compression, a cord artery and vein difference in metabolic acidosis may exist and where the vein captures the basal level and the artery the acute changes. It is concluded that BDecf in both cord artery and vein add valuable information on the mechanisms behind metabolic acidosis.

Acidosis, Lactic↗