Malin Holzmann

Cardiotocography patterns and risk of intrapartum fetal acidemia.

Abstract Aim: To identify cardiotocography (CTG) patterns associated with increased risk of intrapartum fetal acidemia. Methods: A prospective observational cohort study of 1070 women with fetal scalp blood sampling (FBS) during labor was conducted at Karolinska University Hospital, Stockholm, Sweden. Women with a nonreassuring CTG pattern underwent FBS, and lactate concentration was measured at the bedside. Lactate concentrations >4.8 mmol/L were defined as fetal acidemia. A senior obstetrician, blinded to the lactate concentration at FBS, visually interpreted the CTG tracings that had prompted FBS. Results: There were 2134 FBSs performed on 1070 laboring women, constituting 11% of all deliveries at this labor ward. The CTG patterns with the highest frequency of lactacidemia at FBS were late or severe variable decelerations combined with tachycardia (20%–25% at first FBS and 33%–49% at last FBS). With a normal baseline fetal heart rate, normal variability, and absence of serious decelerations, the fetal scalp blood lactate concentration at the first FBS was normal in 97.5% of cases. The group with isolated reduced variability had no increased prevalence of acidemia and median lactate concentration did not differ from the normal group. Conclusion: Isolated reduced variability is in most cases not a sign of hypoxia. If development of hypoxia is ruled out with one FBS, this pattern does not require monitoring with repetitive FBSs throughout labor. Late decelerations and severe variable decelerations increase the risk for intrapartum fetal metabolic acidemia to the same extent. The combination of these decelerations and tachycardia was associated with the highest rate of fetal metabolic acidemia.

Reference values for Lactate Pro 2™ in fetal blood sampling during labor: a cross-sectional study.

Abstract Objective: Lactate Pro™ (LP1) is the only lactate meter evaluated for fetal scalp blood sampling (FBS) in intrapartum use. The reference values for this meter are: normal value <4.2 mmol/L, preacidemia 4.2–4.8 mmol/L, and acidemia >4.8 mmol/L. The production of this meter has been discontinued. An updated version, Lactate Pro 2TM (LP2), has been launched and is shown to be differently calibrated. The aims of the study were to retrieve a conversion equation to convert lactate values in FBS measured with LP2 to an estimated value if using LP1 and to define reference values for clinical management when using LP2. Study design: A cross-sectional study was conducted at a university hospital in Sweden. A total of 113 laboring women with fetal heart rate abnormalities on cardiotocography (CTG) had FBS carried out. Lactate concentration was measured bedside with both LP1 and LP2 from the same blood sample capillary. A linear regression model was constructed to retrieve a conversion equation to convert LP2 values to LP1 values. Results: LP2 measured higher values than LP1 in all analyses. We found that 4.2 mmol/L with LP1 corresponded to 6.4 mmol/L with LP2. Likewise, 4.8 mmol/L with LP1 corresponded to 7.3 mmol/L with LP2. The correlation between the analyses was excellent (Spearman’s rank correlation, r=0.97). Conclusion: We recommend the following guidelines when interpreting lactate concentration in FBS with LP2: <6.4 mmol/L to be interpreted as normal, 6.4–7.3 mmol/L as preacidemia indicating a follow-up FBS within 20–30 min, and >7.3 mmol/L as acidemia indicating intervention.

Reliability in cardiotocography interpretation – impact of extended on‐site education in addition to web‐based learning: an observational study

Previous studies have shown poor reproducibility in cardiotocography (CTG) interpretation. Studies evaluating the Swedish web‐based CTG‐education program have not proven to increase accurate CTG assessments. The aim of this study was to evaluate whether an extended education can improve inter‐ and intra‐observer reliability in CTG interpretation.

Validation of a computerized algorithm to quantify fetal heart rate deceleration area

Reliability in visual cardiotocography interpretation is unsatisfying, which has led to the development of computerized cardiotocography. Computerized analysis is well established for antenatal fetal surveillance but has yet not performed sufficiently during labor. We aimed to investigate the capacity of a new computerized algorithm compared with visual assessment in identifying intrapartum fetal heart rate baseline and decelerations.

Risk factors for intrapartum acidemia – a cohort study

Abstract Purpose: Birth acidemia is associated with short- and long-term morbidity in the child. Optimal intrapartum surveillance and timely interventions may reduce the incidence of these outcomes. Knowledge about conditions which increase the risks might be beneficial for optimal care. The aim with this study was to identify factors which increased the risk for lactacidemia in fetal scalp blood. Materials and methods: A secondary analysis of a cohort study performed at Karolinska University Hospital Stockholm Sweden between February 2009 and February 2011. The study population included 1070 women in labor where fetal scalp blood sampling (FBS) was performed. Results: In a univariate logistic regression analysis for lactate >4.8 mmol/L at FBS, minor language barriers (OR 2.54; 95%CI 1.26–5.11), active bearing down (OR 2.46; 95%CI 1.12–5.39) and maternal height <155 cm (OR 2.15; 95%CI 1.08–4.26) were found as risk factors. In a multivariate logistic regression analysis, minor language barriers (OR 2.21; 95%CI 1.05–4.67) and active pushing (OR 2.68; 95%CI 1.20–6.00) remained significant. Conclusions: Language barriers, active pushing and short stature were found to be significant risk factors for intrapartum lactacidemia. In the group with minor language problems better use of interpreters might be beneficial.

Admission cardiotocography: A hospital based validation study

OBJECTIVE Admission CTG is a short fetal heart rate (FHR) tracing recorded immediately at hospital admission to avoid unnecessary delay in action among pregnancies complicated by pre-existent fetal distress. There are different opinions regarding the value of the admission CTG, especially in low risk pregnancies. STUDY DESIGN A retrospective validation study from Karolinska University Hospital, Jan 2011 to June 2015 (total number of deliveries = 40,061). All women who underwent emergency cesarean section within one hour of admittance due to suspected fetal distress were identified. We assessed whether an admission CTG was performed, if it was beneficial for the decision to perform emergent cesarean delivery and if there were objective signs of fetal compromise or if it was performed unnecessarily. The main outcome was the benefit of the admission CTG in the decision to perform emergency cesarean delivery. RESULTS Eighty-eight cases (0.22%) fulfilled our inclusion criteria. Over 90% of these women (80/88) had objective evidence of compromised fetal well-being, i.e., indicating that emergent delivery was necessary. In 74% (54/73) of all cases was admission CTG determined to have been beneficial in the decision to perform cesarean delivery, equally effective of those classified as low- and high risk pregnancies before admission. In 28% (15/54) the CTG pathology was deemed difficult to identify by auscultation. CONCLUSION Admission CTG was deemed beneficial in 74% of both low- and high-risk pregnancies that were delivered by emergent cesarean section within one hour of admittance due to suspected fetal distress.

Fetal heart rate short term variation during labor in relation to scalp blood lactate concentration

Fetal heart rate short term variation (STV) decreases with severe chronic hypoxia in the antenatal period. However, only limited research has been done on STV during labor. We have tested a novel algorithm for a valid baseline estimation and calculated STV. To explore the value of STV during labor, we compared STV with fetal scalp blood (FBS) lactate concentration, an early marker in the hypoxic process.