[Patent foramen ovale and the risk of paradoxical embolization of venous bubbles in divers - cave for foam sclerotization of varicose veins]

INTRODUCTION

Foam sclerotization of varicose veins may cause paradoxical embolization through patent foramen ovale (PFO). The aim of our study was to: 1) select an optimal screening method for the detection of PFO; 2) determine the prevalence of PFO in a non-selected population; and 3) test the risk of paradoxical embolization of venous bubbles in patients with PFO.

MATERIALS AND METHODS

A diver after decompression is a suitable model for determining the risk of paradoxical embolization of venous gas bubbles. 329 Czech divers were screened for PFO. In a pilot study, we compared Transcranial Doppler Sonography (TCD) with Transesophageal Echocardiography (TEE) in 100 patients. TCD alone was used for further screening. In 31 divers with PFO, nitrogen bubbles were detected after simulated dives. Transthoracic Echocardiography (TTE) was used to detect venous bubbles in right-sided heart chambers; TTE and TCD were used to detect arterial bubbles. The right-to-left shunt was rated as non-significant (<20 arterial bubbles) or significant (20 arterial bubbles). Different decompression regimens were compared.

RESULTS

In the pilot study, TCD was compared with the gold standard in PFO detection - TEE. The negative predictive value of TCD was 100%, positive predictive value was 92%. Screening was performed in a total of 329 divers, PFO was detected in 85 (25%), significant R-L shunt in 45 (14%). In simulated dive to 50 m maximum depth, venous nitrogen bubbles were detected in 7/8 (88%) divers. In 6/8 (75%) divers, paradoxical embolization was confirmed - nitrogen bubbles were detected in the systemic circulation.

CONCLUSION

PFO prevalence with significant R-L shunt was 14% in the non-selected population of Czech divers. Simulated dives indicate that PFO represents a risk factor for paradoxical embolization of gas bubbles. TCD is a suitable screening method for the detection of PFO and the evaluation of R-L shunt significance. These results are indicative of a possible high risk of paradoxical embolization of gas bubbles and the trombogenic substance in patients with a larger PFO and significant R-L shunt undergoing foam sclerotization of varicose veins.

[Paradoxical embolization and patent foramen ovale in scuba divers: screening possibilities]

INTRODUCTION

The cause of decompression sickness (DCS) in scuba-divers is bubble formation in tissues and in venous blood during ascent. Divers with patent foramen ovale (PFO) have an increased risk of paradoxical embolization to the brain or other vital organs. The aim of our study was to assess the incidence of PFO in scuba-divers with DCS, to compare the group with asymptomatic controls, and to evaluate ultrasound contrast methods suitable for screening.

METHODOLOGY

We examined 28 scuba-divers (more than 100 dives). The right-to-left shunt detection was performed by bubble contrast transthoracic echocardiographic examination (TTE) and transcranial Doppler sonography over arteria cerebri media (TCD) in all divers. In divers with shunting, transoesophageal echocardiography (TEE) was performed to prove PFO.

RESULTS

15 divers had DCS associated with the ascent. In this group, PFO was diagnosed in 53% (8/15). The symptoms of all of them retrospectively were of paradoxical embolization (neurological form of DCS). In the group of asymptomatic divers, PFO was proven on the basis of right-to-left shunt screening in 1 diver (8% 1/13). TCD proved right-to-left shunt in all divers with PFO.

CONCLUSION

DCS can unmask a so far asymptomatic intracardiac right-to-left shunting. PFO is a risk factor for paradoxical embolization in divers. TCD is suitable for screening; TEE is a gold standard in PFO detection. Our results showed that PFO detection is a useful clinical tool after repeated DCS and in all frequent divers and instructors.

FreeCall, a system for emergency-call-handling support

This article describes a system for the optimization of the prehospital assessment of emergency, in cases involving thoraco-abdominal complaints and consciousness problems. This assessment is performed by nurses on the basis of a telephone interview at ambulance dispatch centers. The system has a body of biomedical and policy knowledge available to guide the interview and to provide advice.

Telephone triage of cardiac emergency calls by dispatchers: a prospective study of 1386 emergency calls

OBJECTIVES

To evaluate the handling of potential cardiac emergency calls by dispatchers, to determine their final diagnosis and urgency, and to determine the value of the main complaint in predicting urgency and the ability of the dispatchers to recognise non-urgent conditions.

DESIGN

Prospective data collection and recording of main complaint of emergency calls placed via the 06-11 alarm telephone number with follow up to hospital when the patients were transported and the general practitioner when they were not.

SETTING

Dispatch centres of the emergency medical services in Amsterdam (urban area) and Enschede (rural area).

PATIENTS

1386 consecutive adult subjects of emergency calls placed by citizens about chest problems or unconsciousness not caused by injury.

MAIN OUTCOME MEASURES

Frequency of characteristics of the calls, outcome in diagnosis, and assessment of urgency.

RESULTS

69 (5%) patients were dead when the ambulance arrived. Diagnosis was established in 1071 patients (77%). The disorders most often reported were cardiac, with acute ischaemia in 15% of all subjects. In 28% of cases and for each presenting complaint no organic explanation was found. Overall 39% of all emergency calls were urgent; the urgency rate was lowest for calls for people with abdominal discomfort. Dispatchers correctly identified 90% of the non-urgent calls, but 55% of the calls that they identified as urgent proved to be non-urgent.

CONCLUSION

Currently, direct dialling for an ambulance without the intervention of a general practitioner imposes a high work load on emergency systems and hospitals because triage by dispatchers is not sufficiently accurate. It may be possible to increase the accuracy of triage by developing and testing decision algorithms.