The dispatcher’s voice crackled over the radio at 3:33 p.m. on a recent afternoon in the Oak Bluffs emergency medical services headquarters. The dispatcher quickly relayed information. The patient is unresponsive, not breathing. Substance abuse is the suspected medical issue. Within a minute, Oscar 90, the call sign for the town’s main ambulance, was on the way with a crew of three medics. Two others followed in Oscar 93, a response vehicle.

The medics in the ambulance know in the case of an overdose, seconds count. On their way to the scene, they prepare equipment and medications to shave seconds and maybe minutes off their response time. An intravenous bag is readied. A battery-powered heart monitor is positioned, and near the monitor a medic secures the “in bag,” stocked with first line drugs which they can administer in emergency. Among the drugs is naloxone. Medics and police officers know the medication by the brand name Narcan.

Capt. John Rose, Oak Bluffs fire chief, stresses importance of calling for medical help as soon as possible. — Mark Lovewell

At 3:39 p.m., six minutes after the radio dispatch, the ambulance arrives. Medics sprint into the home. The patient is lying flat on his back, unconscious, face turning blue, near death. Medics administer a dose of naloxone in the form of a nasal spray. Within seconds the drug is absorbed through the patient’s nasal membranes. A few seconds later it enters the bloodstream. A couple of heartbeats later, it courses through the capillaries of the brain, where opioid molecules have a death grip on neuron receptors. Opioids from injected heroin have overwhelmed the brain cells, shutting down involuntary body function, including breathing.

The nasal spray buys a little time for the medics. Now they have a naloxone IV drip delivering the drug directly to the patient’s bloodstream. The naloxone molecules flood the brain and begin a war for control of the neurons. Across the brain’s 86 billion neurons, the stronger naloxone molecules begin knocking opioid molecules off the receptors. The overdose is quickly reversed. In less than two minutes, the patient sits up, breathing normally, and asks the medics what happened.

Time is still critical. The nalaxone molecules can only cling to the neurons for a short time. Just 19 minutes after the ambulance arrived, the patient is loaded into Oscar 90. Ten minutes of summer traffic later, the ambulance arrives at the Martha’s Vineyard Hospital emergency room, and doctors take over.

A quick response and a miraculous drug have pried loose the debilitating grasp of heroin addiction, if only for a little while. The insidious grip is so strong that even after overdosing and coming within seconds of death, the addict often succumbs to the habit once again. In at least one case, Island first responders saved a life, only to return the next day to treat the same person for another near-fatal overdose.

Though reliable statistics are difficult to obtain, police officers and medics describe a clear and dramatic increase in opioid overdoses on Martha’s Vineyard over the past six months. Law enforcement officers believe one of the reasons for the sudden increase is the relatively recent practice of drug sellers cutting heroin with fentanyl, a synthetic narcotic that is many times more powerful than morphine. Unsuspecting addicts, injecting what looks like their usual dose of heroin, can easily get a fatal dose if the heroin is mixed with fentanyl. It happens quickly; first responders say often when they respond to an overdose, evidence makes it clear the user has just injected the drug. In one recent case, EMS responded to an overdose victim with a syringe still in his arm.

“It definitely appears to be on the rise,” said Lieut. Eerik Meisner of the Tisbury police department. Tisbury and Edgartown police already carry naloxone on every patrol.

“There’s absolutely a spike in overdoses,” said Oak Bluffs police Lieut. Tim Williamson. His department is close to completing the necessary training and certification to allow officers to carry and administer nalaxone. He estimates within the next two weeks, all officers on duty will be equipped with the nasal form of the drug. “It’s pretty miraculous how it snaps people out of respiratory arrest.”

Naloxone is expensive, costing $40 to $50 per dose. The state budget approved by Massachusetts lawmakers last week includes a provision that will allow the Department of Health to make bulk purchases and stockpile the drug. The savings will be passed on to local ambulance and police departments, who can buy the drug from the DPH.

In June, Gov. Charlie Baker announced a $27 million dollar initiative to combat opioid abuse across the state. The plan calls for more treatment options for addicts, including 100 new treatment facility beds over the next year. The plan will improve the monitoring of prescription pain medications which are often a gateway to heroin use. Public health agencies also plan a statewide education campaign, including state funding for opioid abuse prevention in schools.

Leaders at DPH estimate there were more than 1,000 fatal opioid overdoses in 2014. For every fatality, the agency estimates four more people overdose but are saved with emergency treatment.

Whenever the subject of heroin overdoses comes up, Oak Bluffs ambulance chief John Rose stresses the importance of calling for medical help as soon as possible.

Massachusetts law provides a degree of immunity from prosecution for anyone who calls for medical help to treat an overdose. A person who seeks medical help for themselves or someone else cannot be prosecuted for possession of drugs, if the drugs are found as a result of the call for help. In practice, that means if someone calls 911 and police respond and find a small amount of drugs, the drug evidence cannot be used to prosecute the caller. The exception does not apply for drug trafficking or possession with intent to distribute drugs.

“If somebody happens to overdose, don’t hesitate to call 911,” Mr. Rose said. “The faster we can get there, the better chance they have of surviving. Don’t panic and worry about anything that might happen afterward.”