Dataset Information

Predictive value of traction force measurement in vacuum extraction: Development of a multivariate prognostic model.

ABSTRACT:

Objective

To enable early prediction of strong traction force vacuum extraction.

Design

Observational cohort.

Setting

Karolinska University Hospital delivery ward, tertiary unit.

Population and sample size

Term mid and low metal cup vacuum extraction deliveries June 2012-February 2015, n = 277.

Methods

Traction forces during vacuum extraction were collected prospectively using an intelligent handle. Levels of traction force were analysed pairwise by subjective category strong versus non-strong extraction, in order to define an objective predictive value for strong extraction.

Statistical analysis

A logistic regression model based on the shrinkage and selection method lasso was used to identify the predictive capacity of the different traction force variables.

Predictors

Total (time force integral, Newton minutes) and peak traction (Newton) force in the first to third pull; difference in traction force between the second and first pull, as well as the third and first pull respectively. Accumulated traction force at the second and third pull.

Outcome

Subjectively categorized extraction as strong versus non-strong.

Results

The prevalence of strong extraction was 26%. Prediction including the first and second pull: AUC 0,85 (CI 0,80-0,90); specificity 0,76; sensitivity 0,87; PPV 0,56; NPV 0,94. Prediction including the first to third pull: AUC 0,86 (CI 0,80-0,91); specificity 0,87; sensitivity 0,70; PPV 0,65; NPV 0,89.

Conclusion

Traction force measurement during vacuum extraction can help exclude strong category extraction from the second pull. From the third pull, two-thirds of strong extractions can be predicted.

SUBMITTER: Pettersson K

PROVIDER: S-EPMC5336195 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Publications

Predictive value of traction force measurement in vacuum extraction: Development of a multivariate prognostic model.

Pettersson Kristina K Yousaf Khurram K Ranstam Jonas J Westgren Magnus M Ajne Gunilla G

PloS one 20170303 3

<h4>Objective</h4>To enable early prediction of strong traction force vacuum extraction.<h4>Design</h4>Observational cohort.<h4>Setting</h4>Karolinska University Hospital delivery ward, tertiary unit.<h4>Population and sample size</h4>Term mid and low metal cup vacuum extraction deliveries June 2012-February 2015, n = 277.<h4>Methods</h4>Traction forces during vacuum extraction were collected prospectively using an intelligent handle. Levels of traction force were analysed pairwise by subjective ...[more]

PMID: 28257459

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Project description:BackgroundLow and mid station vacuum assisted deliveries (VAD) are delicate manual procedures that entail a high degree of subjectivity from the operator and are associated with adverse neonatal outcome. Little has been done to improve the procedure, including the technical development, traction force and the possibility of objective documentation. We aimed to explore if a digital handle with instant haptic feedback on traction force would reduce the neonatal risk during low or mid station VAD.MethodsA two centre, randomised superiority trial at Karolinska University Hospital, Sweden, 2016-2018. Cases were randomised bedside to either a conventional or a digital handle attached to a Bird metal cup (50 mm, 80 kPa). The digital handle measured applied force including an instant notification by vibration when high levels of traction force were predicted according to a predefined algorithm. Primary outcome was a composite of hypoxic ischaemic encephalopathy, intracranial haemorrhage, seizures, death and/or subgaleal hematoma. Three hundred eighty low and mid VAD in each group were estimated to decrease primary outcome from six to 2 %.ResultsAfter 2 years, an interim analyse was undertaken. Meeting the inclusion criteria, 567 vacuum extractions were randomized to the use of a digital handle (n = 296) or a conventional handle (n = 271). Primary outcome did not differ between the two groups: (2.7% digital handle vs 2.6% conventional handle). The incidence of primary outcome differed significantly between the two delivery wards (4% vs 0.9%, p < 0.05). A recalculation of power revealed that 800 cases would be needed in each group to show a decrease in primary outcome from three to 1 %. This was not feasible, and the study therefore closed.ConclusionsThe incidence of primary outcome was lower than estimated and the study was underpowered. However, the difference between the two delivery wards might reflect varying degree of experience of the technical equipment. An objective documentation of the extraction procedure is an attractive alternative in respect to safety and clinical training. To demonstrate improved safety, a multicentre study is required to reach an adequate cohort. This was beyond the scope of the study.Trial registrationClinicalTrials.gov NCT03071783 , March 1, 2017, retrospectively registered.

Project description:Mechanical traction forces exerted by adherent cells on their surroundings serve an important role in a multitude of cellular and physiological processes including cell motility and multicellular rearrangements. For endothelial cells, contraction also provides a means to disrupt cell-cell junctions during inflammation to increase permeability between blood and interstitial tissue compartments. The degree of contractility exhibited by endothelial cells is influenced by numerous soluble factors, such as thrombin, histamine, lysophosphatidic acid, sphingosine-1-phosphate, and vascular endothelial growth factor (VEGF). Upon binding to cell surface receptors, these agents trigger changes in cytoskeletal organization, adhesion and myosin II activity to varying degrees. While conventional antibody-based biochemical assays are suitable for detecting relatively large changes in biomarkers of contractility in an end-point format, they cannot resolve subtle or rapid changes in contractility and cannot do so noninvasively. To overcome these limitations, we developed an approach to measure the contractile response of single cells exposed to contractility agonists with high spatiotemporal resolution. A previously developed traction force sensor, comprised of dense arrays of elastomeric microposts on which cells are cultured, was combined with custom, semi-automated software developed here to extract strain energy measurements from thousands of time-lapse images of micropost arrays deformed by adherent cells. Using this approach we corroborated the differential effects of known agonists of contractility and characterized the dynamics of their effects. All of these agonists produced a characteristic first-order rise and plateau in forces, except VEGF, which stimulated an early transient spike in strain energy followed by a sustained increase. This novel, two-phase contractile response was present in a subpopulation of cells, was mediated through both VEGFR2 and ROCK activation, and its magnitude was modulated by receptor internalization. Interestingly, the concentration of VEGF could shift the proportion of cells that responded with a spike versus only a gradual increase in forces. Furthermore, cells repeatedly exposed to VEGF were found to contract with different dynamics after pretreatment, suggesting that exposure history can impact the mechanical response. These studies highlight the importance of direct measurements of traction force dynamics as a tool for studies of mechanotransduction.

Dataset Information

Predictive value of traction force measurement in vacuum extraction: Development of a multivariate prognostic model.

Objective

Design

Setting

Population and sample size

Methods

Statistical analysis

Predictors

Outcome

Results

Conclusion

Publications

Predictive value of traction force measurement in vacuum extraction: Development of a multivariate prognostic model.

Similar Datasets

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