BACKGROUND: Although heart rate variability (HRV) and blood pressure variability (BPV) arise from many different influences, probably the most consistent external modulator is respiration. At rest, the heart rate increases on inspiration and decreases on expiration, a phenomenon called respiratory sinus arrhythmia (RSA). Spectral analysis of heart rate offers good and reproducible estimate of RSA and BPV. Many studies have been conducted on the effects of respiration on HRV and BPV during awake subject breathing spontaneously. However, little is known as to whether respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. Here, we studied effects of respiratory rate on HRV and BPV during general anesthesia. METHODS: We studied 40 patients undergoing general anesthesia with mechanical ventilation. Maintaining anesthesia with isoflurane, we recorded R-R interval and systolic blood pressure at respiratory rate of 15, 10 and 6 breaths/minute. Data was analyzed by the power spectral analyses of HRV and BPV, which were divided into low frequency (LF) and high frequency (HF) band. RESULTS: Respiratory rate did not affect RR interval, systolic blood pressure, and total spectral power HRV and BPV. Compared with its value at 15 breaths/minute, HF-HRV was significantly increased at 6 breaths/minute. HF-and LF-BPV at 6 breaths/minute were significantly increased versus 15 breaths/minute. CONCLUSIONS: Respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. We suggest that respiratory rate should be considered and controlled in studies of cardiovascular variability during general anesthesia.
Anesthesia ; Anesthesia, General* ; Arrhythmia, Sinus ; Blood Pressure ; Heart Rate ; Humans ; Isoflurane ; Respiration ; Respiration, Artificial* ; Respiratory Rate*

OBJECTIVE: We aim to analyze each variable affecting FHR to build objective decision basis using canonical correlation analysis METHODS: The sixty four hundred and fifty five cases of NST from 1988 to 1997 at Hanyang University hospital were collected. We used FHR interpretation softwares, HYFM-I & II those were already developed by author, for extraction of each variable of FHR. We classified the variables into 2 groups, F.A.M(FHR, Amplitude, Mean minute range) and N.S.F(NST weeks, Signal loss, Fetal movement) groups. The Canonical correlation was compared between each variable and group. RESULTS: The canonical correlation between F.A.M & N.S.F are as follows; r=0.40 (p=0.001) in preterm, r=0.34 (p=0.001) in term, and r=0.41 (p=0.004) in postterm. The high linear dependency is shown as r=0.79 (p=0.013) before 23 weeks, the irregular changes shown from 23 weeks to 30 weeks (r=0.47 in 23-24 weeks, r=0.29 in 25-26 weeks, r=0.56 in 27-28 weeks, r=0.24 in 29-30 weeks) and the stable relative changes shown (about r=0.3-0.4) after 30 weeks (r=0.32 in 31-32 weeks, r=0.33 in 33-34 weeks, r=0.37 in 35-36, r=0.33 in 37-38 weeks, r=0.37 in 39-40 weeks, r=0.35 after 41 weeks) (p<0.02). In the linear correlation of FHR, two indicies of FHR variables, AMP and MMR pertaining to N.S.F., FHR(r) is 0.06, AMP and MMR seem to be identical as r=0.30 and then the canonization in term and postterm[FHR(r)=-0.27, AMR(r)=0.23, and MMR(r)=0.35]lies in the regular pattern. Moreover, there is rather a linear correlation between F.A.M and the gestational weeks in preterm and it is changed into linearity similar to zero in term and postterm pregnancies[term(r)=0.01, postterm(r)=0.06] CONCLUSIONS: This study shows the linearity of FHR and the variable which are based on the gestational weeks organically, comprehensibly, and quantitatively. It would be utilized as the fundamental standard of the linearity. The changes from the irregular linear correlation to the regular pattern according to advancing gestational weeks means the changes from the immature and transitional level to the mature level. The closer investigation of the linear and
Female ; Fetal Heart* ; Heart Rate, Fetal* ; Pregnancy

No abstract available.
Female ; Fetal Heart* ; Heart Rate, Fetal* ; Pregnancy

Fetal Heart ; Heart Failure ; Heart Rate, Fetal ; Humans

No abstract available.
Female ; Fetal Heart* ; Fetal Movement* ; Heart Rate, Fetal* ; Music* ; Pregnancy

The monitoring of fetal heart rate (FHR) status is an important method to check well-being of the baby during labor. Since the electronic FHR monitoring was introduced 40 years ago, it has been expected to be an innovative screening test to detect fetuses who are becoming hypoxic and who may benefit from cesarean delivery or operative vaginal delivery. However, several randomized controlled trials have failed to prove that electronic FHR monitoring had any benefit of reducing the perinatal mortality and morbidity. Also it is now clear that the FHR monitoring had high intra- and interobserver disagreements and increased the rate of cesarean delivery. Despite such limitations, the FHR monitoring is still one of the most important obstetric procedures in clinical practice, and the cardiotocogram is the most-used equipment. To supplement cardiotocogram, new methods of computerized FHR analysis and electrocardiogram have been developed, and several clinical researches have been currently performed. Computerized equipment makes us to analyze beat-to-beat variability and short term heart rate patterns. Furthermore, researches about multiparameters of FHR variability will be ongoing.
Cardiotocography ; Electrocardiography ; Female ; Fetal Heart* ; Fetus ; Heart Rate ; Heart Rate, Fetal* ; Mass Screening ; Perinatal Mortality ; Pregnancy

OBJECTIVES: This study is aimed to quantify the complex dynamics of beat-to-beat fetal heart rate(FHR) fluctuations by using approximate entropy(ApEn) which is a recently developed mathematical formula quantifying regularity and also to determine the differences between normal fetuses and growth retarded fetuses. BACKGROUND: Recently, some measures of heart rate variability and nonlinear "complexity" of heart rate dynamics have been used as indicators fetal well-being. Approximate entropy is a new mathematical approach and formula to quantify regularity in data. It has been shown to provide new information in fetal heart rate analysis. Because growth retarded fetus accounts for a significant increase in perinatal morbidity and mortality, than normal fetus, we postulated that there existed important differences between normal fetuses and growth retarded fetuses. METHODS: We analyzed FHR tracings for 40 minutes, and approximately 5,000 points in normal fetuses(n=315) and growth retarded fetuses(n=76). The overall "complexity" of each FHR time series was quantified by its approximate entropy, measure of regularity derived from nonlinear dynamics, "chaos theory". RESULTS: Mean baseline FHR increased in growth retarded fetuses than normal fetuses. And the FHR ApEn significantly decreased in growth retarded fetuses(ApEn=0.623) compared to that of the normal fetuses(ApEn=0.868) throughout all gestational ages(p < 0.001). CONCLUSIONS: The ApEn of FHR decreased in growth retarded fetuses throughout all gestational ages. These findings indicated that decreased ApEn values of FHR are associated with sickness and the greater perinatal morbidity risks. Therefore ApEn quantifies subtle changes in FHR regularity and promises for new information in FHR analysis.
Entropy* ; Female ; Fetal Heart* ; Fetus* ; Gestational Age ; Heart Rate ; Heart Rate, Fetal* ; Mortality ; Nonlinear Dynamics ; Pregnancy

No abstract available.
Female ; Fetal Heart* ; Hearing* ; Heart Rate, Fetal* ; Pregnancy ; Pregnancy*

No abstract available.
Female ; Fetal Heart* ; Fractals* ; Heart Rate, Fetal* ; Pregnancy

No abstract available.
Female ; Fetal Heart* ; Heart Rate, Fetal* ; Meconium* ; Pregnancy