Suppose the mermaids share similar intelligent and technology with us, they also practise performing surgical operation like we do in hospital. Negate the issue of negligent during the operation the most critical problem is contamination that often reduce the chances of success, how can the mermaids negate or reduce the chances of infection during operation underwater? Don't tell me they do it inside dead sea! even so at least touch on how to stabilize their internal blood pressure which is similar to us!
Mermaids perform surgery like this:
- The patient is laid out on a table with the body part to be operated on at the highest point.
- A transparent sea shell is then lowered over the target area.
- Clean air, brought from the surface in shells, is released under the shell until the entire area is "dry". This prevents the blood from clouding the water above the wound.
- The skin is cut with scalpels made from razor-sharp Barracuda teeth.
- The patient is told to "stop screaming, as fish don't feel any pain".
- If that doesn't help, a paralyzing sea snail poison is used to keep the patient still. Note: still, not unconscious
- Blood vessels are clamped shut with tiny fiddler crabs to keep the area clear of blood as much as possible.
- The intended surgery itself is performed with the same tools. Often it consists only of sewing shut tears in organs from battle/shark bite wounds or only exposing any infected tissue.
- The shell is raised slightly to flood the wound.
- Cleaner fish and shrimp are released into the wound to remove any dead or diseased tissue.
- After the cleaners lose interest, and the wound is inspected, the surgeon squeezes antibiotics out of a sea sponge into the wound, then quickly sews it shut with fine fish bone needle and thread made of processed shark cartilage.
- The wound is monitored for a few days by regularly holding cleaner shrimp close to it. If they get excited, anti-infection measures are taken.
- The patient is declared healthy or dead.
As you can see, the mermaids have domesticated and bred a host of small creatures to assist with surgery and medicine. All of these have strong anti-bacterial properties, so that they don't infect patients.
Note: If the mermaids employ technology much closer to ours but somehow don't fancy having airlocks and air-filled surgery rooms in their hospital, they would probably have transparent plastic bubbles that fit over the patients body and have built-in arm gloves. The bubble is then inflated, pumping all the water out and allowing the surgeon to work in clean air.
A clean room makes just as much sense underwater as on dry land. Just fill a room with purified and oxygenated saline/water. Mount some pumps outside with a reserve of additional purified and oxygenated saline/water and pump it in as needed to wash away the stale and blood contaminated water.
As for maintaining vascular blood pressure,... clamps and shunts, just like on dry land.
They actually do not use similar technology as we do. Their technology is based on energy and frequencies. Instead of removing a cancerous growth with a scalpel, they harness the resonant frequency of the aether and transduce it to the resonant frequency of the particular cancer virus/fungus (cancer is polymorphic) and destroy the cells in vitro. They also cure headaches in similar ways. They use the same technology to help heal damaged tissue.
Part of the reason they are not able to use technology as we understand it is because saltwater is the arch-enemy of electricity and electronics.