From asking some doctors about your situation, it seems to us that you are not to blame from a technical point of view; the role of emergency medical personnel is in the vicinity of the incident, where they are to do whatever they can to treat those who are injured, and that role ends when they hand over the injured persons to the emergency ward doctor.
The work of the emergency ward doctor begins when the injured person is handed over to him and he does not have the right to base serious decisions on what the emergency worker says. The doctor has to do whatever he can for the injured person, regardless of what the emergency worker says, which may be lacking or mistaken.
Removing resuscitation equipment from the patient is not to be based on the testimony of an emergency worker; rather it is to be based on the opinion of a specialist doctor after allowing enough time to hook the patient up to the resuscitation equipment.
The patient can only have arrived at the hospital alive or dead. If he was alive upon arrival, the resuscitation equipment should not be removed except following the decision of three specialist doctors. If he was dead on arrival, there is no need for resuscitation equipment in the first place. These two scenarios have been discussed in the answer the question no. 115104.
Thus it becomes clear that the responsibility lies with the doctor and not with the ambulance worker.
Based on that, it does not seem that you are to blame for whatever happened with the patient, so there is no need for anxiety or distress. We ask Allah to have mercy on the deceased if he was a Muslim.
You have to do your job well and fear Allah with regard to patients and accident victims, and to be certain and definitive with your testimony.
You said that you were fasting and you were exhausted because of fasting. It should be noted that if fasting will lead you to fall short in your work, which may expose accident victims to danger, then you have to break the fast. This applies if your fast was obligatory. If it was a naafil fast, then the matter is even more clear.
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allah have mercy on him) said:
Whoever breaks the fast in order to save a person who is drowning or being burned in a fire and is one who has to be saved, then he should break his fast and make it up later on. For example, if you see a house that is on fire and there are Muslim people inside, and you cannot fulfil the duty of saving them except by breaking the fast and drinking water so as to have the strength to save these people, then it is permissible for you – and is indeed obligatory upon you – in this case to break the fast in order to save them. The same applies to these who work as firefighters; if a fire occurs during the day and they go to rescue someone and they cannot do that except by breaking the fast and eating food to give them physical strength, then they should break the fast and eat that which will give them physical strength. End quote.
Majmoo‘ Fataawa al-Shaykh al-‘Uthaymeen, 19/163
And Allah knows best.