Question: 

The incidence of patent foramen ovale is about 25–30% in adults and more frequent in the childhood. During laparoscopic surgery insufflations of the abdominal cavity leads to an increase of the intra-abdominal pressure (IAP). Is it feasible to predict atrial right-to-left shunting by measurement of the pressures of the right atrium (P_RA) or of the superior caval vein (P_vcs)?

Methodology: 

Seventeen piglets (mean 11.1±1.2 kg) were randomized into two groups. Anesthesia and controlled ventilation were performed throughout all procedures. In eight animals after transseptal puncture an artificial ASD of 5.6±3.2 mm was created with a balloon catheter. The IAP was raised to 8 and 16 mmHg with intermittent desufflation in 20 minute periods. Right-to-left shunting was visualized by echocardiography. Central lines allowed registration of the pressure of the inferior caval vein (P_vci), P_vcs, P_RA and of the pulmonary wedge pressure (PCWP). (approved study 1.5177-07-04/G07-1-014).

Results: 

Echocardiographic investigations revealed right-to-left shunting in seven piglets of the ASD-group. The contrast media was seen temporary at begins of ventricular contraction in the left atrium. IAP elevations led to increases only in P_vci (DP_vci: ASD-group 5.7±4.4, 9.5±2.2 mmHg, control-group 4.4±3.2, 9.1±8.9 mmHg, at IAP 8, 16 mmHg respectively). P_RA and P_vcs were unaffected by IAP elevations. Even systolic, diastolic and mean differences between P_RA-PCWP were no indicators for shunting.

Conclusion: 

Measurements of the central venous or right atrial pressures are not sufficient to indicate the risk of paradoxical embolism during laparoscopy. In elective surgery it should be recommended to perform echocardiography preoperatively.