I don't suggest avoiding medical treatment however my little one never has an asthma attack when we are close to home, the doctor, or the hospital. These are a few tips that will help buy you time or bring them back down when they are worked up. This way you can continue with their normal treatments when you are able.
A quick favorite of my daughter is the cold coffee trick. She hates the taste but knows that it will do the trick quickly. Coffee contains high doses of caffeine and is a bronchial stimulator. It will open the throat and the coldness reduces swelling if they have been coughing up to that point.
Ice packs under the arm can help reduce the inflamed lungs and bring breathing back to a normal pace. Be sure not to apply them directly to the skin. Wrap the packs around under the arm and across the chest. My daughter hates this one but if they are really worked up this brings breathing down quickly.
Throwing up is normal. They cough and hack and can't get a breath. When you vomit it clears your throat of mucus. Don't try to stop them it will help and can buy you up to an hour to get them to the hospital. The only concern is making sure they are upright and tipped over so that they don't choke or aspirate. Aspirating vomit occurs when they inhale the substance and can cause pneumonia. I avoided this by teaching my daughter to spit like a boy before she tries to take a breath. Not only does spitting clear their mouth but my daughter loves the idea that even for a few minutes she can be a tom boy. To date she has most boys beat for how far they can spit.
Hot and moist can help. If you have a humidifier, crank it up to the highest setting in a small room with the child. Back before wonder drugs people would turn the hot shower on and put their kid in the bathroom as a treatment. This one is great for when you are on vacation. A sink running hot water with a towel over their head also works well. I have been there....you do what you can at a rest stop with 50 miles to the nearest town.
If you find yourself without an extended chamber for smaller kids and you need to get them to take their inhaler a bag or other small container can work as a quick fix. I once bought a plastic cup from a gas station and cut a hole only big enough for the inhaler on one end. The kiddie cups are the perfect size for this and fit over their mouths the best. The real chamber had rolled to the bad of the car under the seats but you don't have time to pull everything out when an attack is full blown. My daughter and her doctor liked the chamber so much I gave the original to the doctor and made her a new one. He keeps it for those first time education classes for parents for his short segment on how to get creative when it is needed. You can't get a chamber with random cartoons on it any where.
Most of all keep your head. If you freek out your kid will see it and know that all control is lost. This is the exact opposite and will escalate their attack.