Correction to: Adv Simul 3:9 (2018)
https://doi.org/10.1186/s41077-018-0068-3
Continuing work on a recently published empirical model for educational simulation of cervical dilation [1] resulted in identification of errors in the code implementing this model. Numerical values of three parameters and one state variable had to be updated to obtain the original simulation results with corrected code. The errors identified in the original code included incorrect assignment of the value of the parameter that governs the dilation increase due to pressure exerted by the fetus on the cervix, a discrete time step specified in hours with parameters using minutes as a time reference, numerical integration of a static equation, and unnecessary capping of the uterine contraction amplitude. In the MATLAB code listed in the appendix, these errors are corrected. To obtain the originally published simulation results for cervical dilation, three parameter values had to be adjusted, see Table 1.
On closer inspection, it was also found that the value of the parameter AFR50 of 7.9 mU/min in [2] was incorrectly assigned to P6, which is a concentration in mU/mL. In semi-steady state it can be derived from Eqs. (2, 3) of the original paper that the updated value listed in Table 1 corresponds to the concentration in steady state on an infusion of magnitude AFR50 for the given pharmacokinetic parameters P3 and P4. The evolution of drug mass over time is given by the pharmacokinetic equation, Eq. (4) of the original paper. In semi-steady state, drug mass is proportional to infusion rate. This value is assigned to m (0) in Table 1. Simulation results for cervical dilation using corrected code and adjusted numerical values match the results presented in the original paper in good approximation. The conceptual model and all presented model equations stood up to this additional scrutiny.
References
Gefferie SR, Scholten AWJ, Wijlens KAE, Ferreira-Bastos ML, van der Hout-van der Jagt MB, Zwart H, et al. An empirical model for educational simulation of cervical dilation in first stage labor. Adv Simul. 2018;3:9 1–4.
Lobo MF, Bastos LF, van Meurs WL, Ayres-de-Campos D. A model for educational simulation of the effect of oxytocin on uterine contractions. Med Eng Phys. 2013;35(4):524–31. https://doi.org/10.1016/j.medengphy.2012.06.021.
Acknowledgements
The authors thank Eva Kleinveld and Lex van Loon for their help in identifying and correcting the programming errors.
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Appendix
Appendix
Corrected and verified Matlab code
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Gefferie, S.R., Scholten, A.W.J., Wijlens, K.A.E. et al. Correction to: An empirical model for educational simulation of cervical dilation in first stage labor. Adv Simul 6, 34 (2021). https://doi.org/10.1186/s41077-021-00184-y
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DOI: https://doi.org/10.1186/s41077-021-00184-y