Impedance cardiography as tool for continuous hemodynamic monitoring during cesarean section: randomized, prospective double blind study

Effectiveness of Combined Strategies for the Prevention of Hypothermia Measured by Noninvasive Zero-Heat Flux Thermometer During Cesarean Section

Background: Perioperative hypothermia (body temperature <36°C) is a common complication of anesthesia increasing the risk for maternal cardiovascular events and coagulative disorders, and can also influence neonatal health. The aim of our work was to evaluate the impact of combined warming strategies on maternal core temperature, measured with the SpotOn. We hypothesized that combined modalities of active warming prevent hypothermia in pregnant women undergoing cesarean delivery with spinal anesthesia. Methods: Seventy-eight pregnant women were randomly allocated into three study groups receiving warmed IV fluids and forced-air warming (AW), warmed IV fluids (WF), or no warming (NW). Noninvasive core temperature device (SpotOn) measured maternal core temperature intraoperatively and for 30 min after surgery. Maternal mean arterial pressure, incidence of shivering, thermal comfort and newborn's APGAR, axillary temperature, weight, and blood gas analysis were also recorded. Results: Incidence of hypothermia was of 0% in AW, 4% in WF, and 47% in NW. Core temperature in AW was constantly higher than WF and NW groups. Incidence of shivering in perioperative time was significantly lower in AW and WF groups compared with the NW group (p < 0.04). Thermal comfort was higher in both AW and WF groups compared with NW group (p = 0.02 and p = 0.008, respectively). There were no significant differences among groups for the other evaluated parameters. Conclusion: Combined modalities of active warming are effective in preventing perioperative hypothermia. The routine uses of combined AW are suggested in the setting of cesarean delivery.

Measurements of cardiac efficiency and internal work of the left ventricle via reconstructed impedance cardiography

Objective. The aim of this study was to investigate methods for measuring the cardiac efficiency (CE) and internal work (IW) of the left ventricle via reconstructed impedance cardiography (RICG).Approach.On the basis of the physiological context and Bernoulli's equation in physics, methods of measuring the CE and IW were proposed. The CE, IW, internal work index (IWI), and other data from 180 healthy adults and 144 patients with cardiovascular disease were measured.Main results. The CE of 180 healthy adults was 22.5 ± 2.2%, and the IWI was 22.3 ± 5.2 J l^-1m^-2. CE decreased with age, and the CE of the younger group (23.5 ± 1.9%) was larger than that of the older group (21.5 ± 1.9%),P < 0.01. The IWI increased with age, and the IWI of the younger group (19.0 ± 3.8 J l^-1m^-2) was smaller than that of the older group (24.8 ± 4.3 J l^-1m^-2),P < 0.01. There were no significant difference in CE (22.4 ± 2.2% and 22.6 ± 2.2%) or in the IWI (21.9 ± 5.1 J l^-1m^-2and 22.6 ± 5.2 J l^-1m^-2) between the male and female groups. The CEs and IWIs of patients with hypertension, coronary heart disease, and heart failure were 17.4 ± 2.4% and 41.8 ± 15.6 J l^-1m^-2, 17.6 ± 3.0% and 35.1 ± 10.4 J l^-1m^-2, and 15.8 ± 3.5% and 42.1 ± 15.6 J l^-1m^-2, respectively. These CEs were all smaller than that (21.6 ± 2.0%) of the healthy contrast groupP < 0.01, while the IWIs were all larger than that (24.6 ± 4.8 J l^-1m^-2) of the healthy contrast group,P < 0.01.Significance.The CEs and IWIs measured in this study may reflect physiological changes in healthy humans and pathogenic conditions in patients with cardiovascular disease.

Hemodynamic differences among hypertensive patients with and without heart failure using impedance cardiography

Background:

Impedance cardiography is a reliable, well-tolerated, and non-invasive method used to obtain hemodynamic measurements and could potentially be useful in heart failure (HF) diagnosis, hemodynamic monitoring of critically ill patients, and help in the choice of antihypertensive therapy. The objective of this study was to determine the differences between hemodynamic parameters in a study population of hypertensive patients with and without HF, using impedance cardiography.

Methods:

A case-control study was designed and named the TARGET study. Participants were enrolled in two study groups: control group C, hypertensive patients without HF and the HF group, hypertensive patients with HF. A descriptive analysis was carried out to characterize the sample and differences in continuous variables were tested for statistical significance by independent sample t test.

Results:

The study included 102 hypertensive outpatients. The control group consisted of 77 individuals (58.4% males; mean age 63.9 ± 12.5 years old) and the HF group consisted of 25 individuals (44.0% males; mean age 74.2 ± 8.7 years old). The mean Cardiac Index (CI) was 2.70 ± 1.02 L.min.m⁻² (2.89 ± 1.04 versus 2.12 ± 0.70; p < 0.001), mean Stroke Index (SI) was 35.5 ± 14.7 mL.m⁻² (37.7 ± 15.2 versus 28.5 ± 10.8; p = 0.006), mean Ejection Phase Contractility Index (EPCI) was 33.7 ± 12.7 1000 s⁻² (35.8 ± 13.1 versus 27.2 ± 9.2; p = 0.003), mean Inotropic State Index (ISI) was 74.3 ± 28.2 100 s⁻² (78.8 ± 28.9 versus 60.6 ± 20.7; p = 0.005), and mean Left Stroke Work Index (LSWI) was 51.3 ± 23.1 g.min.m⁻² (55.4 ± 23.5 versus 38.9 ± 16.6; p = 0.002).

Conclusions:

In this study, hypertensive patients with HF had significantly lower values of blood flow parameters, contractility, and left work indices compared with hypertensive patients without HF. These differences reflected the incorrect hemodynamic pattern (mostly hypodynamic) of these patients. Impedance cardiography (ICG) seems to be an adequate method to reflect these differences.

Waveform analysis of differential graphs of reconstructed impedance cardiography from healthy individuals

Purpose

The aim is to measure and analyze the wave amplitudes and time intervals of differential graphs of reconstructed impedance cardiography (RICG).

Methods

180 adults with normal cardiac function between the ages of 18–78 were included in the study. Six mingled impedance changes on chest surface were simultaneously detected for each subject. The differential graphs of five impedance change components of RICG were obtained through waveform separation and software differentiation. The amplitudes of C, X, O, b waves and time intervals of Q‐b and Q‐C were measured and statistically analyzed.

Results

The amplitudes of C and X waves in PL, PR, AO, and that of C, O, b waves in LV and RV, all decrease as age increases. Wave amplitudes of the female group were bigger than those of the male group (p < .01), while the Q‐C intervals of the female group were shorter than that of the male group (p < .01). Among five impedance change components, the wave amplitude of AO was larger than those of PL and PR (p < .01), and wave amplitudes of PL and PR were bigger than those of LV and RV (p < .01). Q‐C intervals of LV and RV were longer than those of AO, PL and PR (p < .01), while the Q‐b intervals of LV and RV were shorter than the Q‐C intervals of AO, PL, and PR.

Conclusions

The differential graphs of RICG could reflect indirectly the physiological activities and pathological changes of the heart and of the large blood vessels in thorax.

Cardiovascular Outcomes in Advanced Maternal Age Delivering Women. Clinical Review and Medico-Legal Issues

Background and objecives: Adverse cardiovascular outcomes during pregnancy have increased over the past few decades, with increased numbers of women delivering later in their reproductive life. Other factors include higher rates of female obesity, diabetes, hypertension, cardiovascular diseases and assisted reproductive technology, which has extended fertility. Those at risk require extensive prenatal maternal screening, constant pregnancy supervising, monitoring during labor, delivery and puerperium and careful anesthetic evaluation during delivery. Materials and Methods: The present review reports the relevant information available on cardiovascular outcomes in advanced maternal age delivering women and related medico-legal issues. The search was performed on Pubmed, Cochrane, Semantic Scholar, Medline and Embase databases, accessed by Ovid, including among others the terms "cardiomyopathy", "ischaemic heart disease", "arrhythmias", "hypertension", "peripartum period", "diabetes", "advanced maternal age" "anesthesia", "maternal morbidity and mortality" and "litigation". Results: To the extent that underestimating risk factors for peripartum cardiomyopathy (PPCM) can adversely impact maternal and fetal outcomes, the legal implications of misdiagnosis or mismanagement can result in high compensatory damages. Substantial indemnity payments drive up costs of insurance coverage. Conclusions: Multidisciplinary approaches are necessary from obstetricians, cardiologists, anesthesiologists and perinatologists for pregnancy monitoring and delivery outcomes.