Background & Aims

Pulmonary function in pregnant women is altered due to the presence of the foetus and elevation of the diaphragm(1,2). The electrical impedance tomography (EIT) measures non-invasively atelectasis, through changes in the thoracic impedance(3,4). Very few applications of this technique have been studied in anesthesia(5) The purpose of the present study was to assess by EIT the effects of lumbar epidural analgesia on ventilation, in pregnant women, during labor, in sitting position.

Methods

After Institutional Ethics Committee approval and written consent, 37 adult ASA 2 at term pregnant patients were studied. The belt of the EIT (PulmoVista 500, Draeger) was placed around the patient’s thorax at Th4–Th6 level(6). The study recordings were done 10 minutes before and after insertion and loading of the epidural analgesia. Student’s paired t-test with the Bonferroni correction was applied to compare data before and after epidural analgesia, for the global and regional ventilation. Data are expressed as mean [95%CI].

Results

Good levels of analgesia were obtained in all cases (VAS 8,43 vs 0,97 [ -8,208 to -6,710], p<0.001), with upper sensory levels reaching from Th4 to Th10. Atelectasis was seen in all patients before the epidural analgesia, with better ventilated regions centrally than peripherally. No effects of epidural analgesia on atelectasis were noted neither for the global, nor for regional ventilation (Figure 1). No adverse events were associated to Electrical Impedance Tomography use.

Conclusions

This is the first study assessing lung atelectasis before and after epidural analgesia during labor. The changes in lung volumes, as demonstrated by this study, are mostly due rather to the mechanical pushing of the abdominal content towards the diaphragm and lung, and not to shallow breathing due to pain. Further studies in left lateral position are needed.

References

1.Cugell DW, Frank NR, Gaensler EA, Badger TL. Pulmonary function in pregnancy. I. Serial observations in normal women. Am Rev Tuberc. 1953;67(5):568-97.
2.Bobrowski R. A. (2010). Pulmonary physiology in pregnancy. Clinical obstetrics and gynecology, 53(2), 285–300. https://doi.org/10.1097/GRF.0b013e3181e04776
3.Bodenstein M, David M, Markstaller K. Principles of electrical impedance tomography and its clinical application. Crit Care Med. 2009;37(2):713-24.
4.Faes TJ, van der Meij HA, de Munck JC, et al: The electric resistivity of human tissues (100 Hz-10 MHz): A meta-analysis of review studies. Physiol Meas 1999; 20:R1–R10
6.Erlandsson K, Odenstedt H, Lundin S, et al: Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgery. Acta Anaesthesiol Scand 2006; 50:833–839
7.Draeger EIT booklet; https://www.draeger.com/Content/Documents/Products/eit-bk-gesamt- 9067044-fr-1508-2.pdf

Presenting Author

Stefano Doria

Poster Authors

Stefano Doria

M.D.

Erasmus Hospital, Brussels, Belgium

Lead Author

Laszlo Szegedi

Erasmus Hospital, Brussels, Belgium

Lead Author

Alexandra Colesnicenco

Erasmus Hospital, Brussels, Belgium

Lead Author

Younes Ghamgui

Erasmus Hospital, Brussels, Belgium

Lead Author

Senada Ymeraj

Erasmus Hospital, Brussels, Belgium

Lead Author

Annalinda Ciorra

Erasmus Hospital, Brussels, Belgium

Lead Author

Turgay Tuna

Erasmus Hospital, Brussels, Belgium

Lead Author

Thibaut Decoeur

Erasmus Hospital, Brussels, Belgium

Lead Author

Topics

  • Specific Pain Conditions/Pain in Specific Populations: Obstetric and Labor Pain