Trench Collapse with Two Buried Workers and No Gas Detector
14:20: the sides of a 3.5 m deep excavation for a sewer connection in a densely built neighbourhood shear off. The trench is vertical, unshored, cut through sandy loam, and a broken 2-inch water line is spraying into it. Worker 1 is buried to mid-thigh, conscious, complaining of severe pain in both legs and back; worker 2 is buried to the chest, head slumped forward, not responding and not visibly breathing; a third worker got out and is shouting that you must just pull them out now. The spoil heap sits 1 m back from the edge and a 3-tonne concrete mixer is parked 2 m from the lip. A crowd of about 40 people has gathered. Your rescue tender carries aluminium shoring panels, a tripod, ropes and a basket stretcher; the four-gas detector was left charging at the station; the fire service is 18 minutes away and the nearest hospital 20 minutes. It is 41 °C.
1. It is 14:22. State your first five actions in order and explain why the crew does not simply pull worker 1 out by the arms.
Read the worked answer
- Remove the inputs to the collapse: shut down and move the 3-tonne mixer back, and pull the spoil heap back from the lip. A machine 2 m from an unshored edge is a live surcharge load, and its vibration alone can trigger a second shear. 2) Stop or divert the water: ask the third worker or a bystander to close the 2-inch valve upstream; if that cannot be done within a minute, divert the flow away from the trench rather than sending anyone in. 3) Establish an exclusion zone of 10 m, push the crowd back to about 30 m, and appoint one person whose only job is watching the trench walls and calling evacuation. 4) Radio for the fire service, the water utility, a second rescue team and an excavator with a lifting plan. 5) Shore before entry: panels or trench sheets, a top brace, and a ladder within reach of each worker.
Pulling worker 1 out by the arms fails for two reasons. Traction against soil gripping both legs tears tissue and can release a crush load abruptly, producing a fatal arrhythmia at the moment of release; and the trench is still failing, so the rescuer becomes the third casualty and the operation stops entirely while he is recovered.
2. Worker 2 is buried to the chest and not breathing. Describe what you can and cannot do, and state when you would stop.
Read the worked answer
Soil compressing the chest means you cannot ventilate: the lungs cannot expand, and bag-valve-mask or mouth-to-mask against a fixed chest only inflates the stomach and delays the real intervention. Removing soil down to chest level is therefore the airway manoeuvre, and it must be done by people working from outside the trench with long-handled tools, or by a shored, harnessed rescuer with an attendant and a tripod line. Until the chest is free, everything else is futile.
Sequence: shoring at the level above the casualty, a harnessed rescuer on the line, spoil removed in buckets, then clear the airway, look-listen-feel, and ventilate. Stop criteria: if, once the chest is free, there is no breathing and no pulse, and burial time exceeded roughly 15 minutes with asphyxial signs, survival is effectively nil. With a second live casualty and a small crew, that time should transfer to worker 1. Record the times, cover the casualty, and hand over to police. Note also that even 30 cm of muddy water in the trench bottom is a drowning risk for a non-responsive casualty, which is another reason to divert the water early.
3. Worker 1's extrication will take about 40 minutes. Set out the clinical care and the specific risk that releasing his legs creates.
Read the worked answer
He has had both legs compressed and a back injury for over 40 minutes, so think crush syndrome before release, not after. Within EMT scope: high-flow oxygen, keep him warm and shaded, continuous monitoring of pulse, blood pressure, respiratory rate and ECG, analgesia, and spinal precautions based on mechanism and pain. Do not apply traction to the spine, and splint the legs after release rather than before.
The dangerous moment is release: reperfusion causes hypotension and a potassium surge, with peaked T waves, a widening QRS and bradycardia within minutes. So release deliberately and in stages, with a rescuer whose only job is watching the monitor, and pre-alert the receiving hospital that a crush patient is coming who may need fluid resuscitation, calcium and renal support. If intravenous crystalloid is within local protocol, start it before release.
Crew safety matters here too: at 41 °C, with PPE and physical work, heat illness is a real risk. Rotate roles, enforce drinking, and shade the working area, because a collapsed rescuer ends the operation for worker 1.