DUSSELEDORF, Germany — The world’s largest medical trade fair opened here on Wednesday, with organizers claiming in excess of 4,800 exhibitors from 65 nations for the event, which runs through Saturday.

The combination of two shows — Medica and CompaMed 2007, an exhibition dedicated to upstream suppliers to the medical products manufacturing sector — is expected to surpass last year’s record attendance of 137,500.

The event fully occupies the massive Dusseldorf Messe complex, filling all 20 exhibition halls and spilling out to the parking lots with demonstrations of mobile medical products and medically focused Airstream trailers and RVs packed with specialized gear.

Over two-thirds of Medica exhibitors come from outside Germany, with the largest contingents coming from the U.S. with 362, China with 344, Italy with 320, Great Britain with 250 and France with 204.

Troubling news rippled through the packed exhibition halls as posters went up during registration announcing a combined national and regional rail strike that was timed to coincide precisely with Medica 2007, due to end exactly as the show winds down tomorrow.

Housing the massive crowds over four days means participants and exhibitors alike stay in cities as far away as Essen or even Cologne and depend on the trains to commute to the show.

Municipal transportation service unions are not participating in the strike, assuring at least local transport to and from the show. Participants telling tales of exaggerated taxi fares expect further price pressure in the coming days.

Medica and CompaMed also are bringing a windfall to the German medical technology sector, which has been moving at a sluggish 3% growth rate for years.

Forecasts from the industrial associations SPECTARIS and ZVEI are predicting a strong 8% growth for the German domestic market in 2007, finishing at €6 billion ($8.8 billion)

Foreign trade is expected to post 7% growth to €11 billion ($16.2 billion) by year-end despite a rapidly strengthening Euro. The worldwide market for the equivalent trade sectors measured by the German associations is estimated to be $278 billion.

Medica is so large it seems a wonder equal to some of the medical technology on display that it comes together at all.

Though the 20 exhibition halls of the sprawling complex are roughly organized by medical product groups to bring some sense of order, there are overlapping themes and increasing blurred lines between products groups, for example the convergence of medical imaging and information systems, or home monitoring devices and the different pathologies being monitored at home.

Add to this the grouping of companies by national origin under special pavilions, and then the special set-aside of halls dedicated to foreign delegations and the confusion of the marketplace re-emerges, leaving the visitor wandering from syringes to hip implants to advanced diagnostics in just a few dozen meters.

The opening of the show seemed to be enough news for one day at Medica.

Only one new product, a pocket-size ultrasound device that Siemens Medical Solutions (Erlangen, Germany) touts as the world’s smallest, was launched at the start of the show. None of the industry’s major manufacturers scheduled media events, apparently preferring to reserve new products for more focused events at a later date where impact in a specialized practice area is greater.

Siemens’ ultrasound device, Acuson P10, is a mini-device the size of a smartphone and weighs just one and one-half pounds. Targeted for emergency situations, the device is intended primarily for initial diagnosis and assessment of the severity of the injury, for instance in cardiology or in the case of abdominal complaints. Secondary applications include helicopters, ambulances or intensive-care wards.

The Acuson P10 complements a progressive miniaturization of the Siemens ultrasound line. Also on display at Medica is the Acuson P50, a laptop-based system that integrates echocardiography software designed for highly mobile use as well as vascular applications. Combined with an array of transducers and compatible with Microsoft Windows operating systems, the Acuson P50 aims to be a flexible anywhere/anytime tool for diagnotics image capture and display.