Thai Cave Rescue: Details for Preventing Hypothermia, Panic

Tara Haelle

April 03, 2019

The harrowing details of the rescue operation that saved 12 adolescent Thai soccer players and their coach from Thailand's monsoon-flooded Tham Luang cave were reported shortly after the effort ended, but the specifics of their medical care before, during, and after the rescue have been hazy. Now, a research letter published online today in the New England Journal of Medicine details how the medical team prepared each boy for the approximately 6-hour journey from their ledge to the cave mouth.

Initially, officials expected that the boys would need to remain in the cave for several months until the monsoon season ended, but "with impending monsoon rains and concerns about falling oxygen levels in the cave, a plan to urgently extricate the patients was developed," write Maj. Chanrit Lawthaweesawat, MD, of the Medical Association of Thailand and Bumrungrad International Hospital, both in Bangkok, and three colleagues on the medical team.

The team, led by coauthor Maj. Gen. Wutichai Isara, MD, included 50 to 60 physicians and more than 100 medical personnel who were on duty each day, plus a backup team standing by around the clock, Lawthaweesawat told Medscape Medical News.

Among the biggest concerns was hypothermia, the authors explain, because the boys spent approximately 2 hours submerged in water that was near 20° Celsius as a certified cave diver transported them toward the exit. Throughout the rescue, two patients developed mild hypothermia, one on the first day and one on the second day of the rescue.

Initially, the greatest concern was with regard to the third day, because the last group of boys were younger and smaller than the others. However, "the transfer process was very fast" and none of the boys developed hypothermia because the group knew the protocols well by that point, Lawthaweesawat told Medscape Medical News.

Because of the length of each one-way journey to the cave mouth, much of it underwater and through narrow, flooded passages, the team also worried about the boys panicking. Each boy therefore received alprazolam 0.5 mg orally and an intramuscular injection of atropine 20 μg/kg, followed by an intramuscular loading dose of ketamine 5 mg/kg.

Sedation was atypical for such a rescue operation, but "it was one of the those on-site decisions that was certainly reasonable to proceed with," Col. Will Smith, MD, of the US Army Reserve, who is medical director of Teton County Search and Rescue, Grand Teton National Park, and other national parks teams, told Medscape Medical News.

The boys had never dived, and after spending a week alone in the cave without food and with little water before being found, "their state of mind was certainly a concern," Smith said. Although not involved with this particular rescue, Smith, who is also a clinical assistant professor at the University of Washington School of Medicine, Seattle, consults in search and rescue operations as owner of Wilderness and Emergency Medicine Consulting.

Ketamine was an ideal choice of sedation because it can be given intramuscularly — and therefore underwater through a wet suit, while the person is unconscious if necessary. Ketamine was able to anesthetize the boys adequately to ensure that their muscles were relaxed during the trip. This enabled the diver to carry them without the boys being aware of the dangerous, potentially frightening conditions, Lawthaweesawat told Medscape Medical News.

In addition, "ketamine is the only medicine that can still maintain respiration and blood pressure throughout the journey," coauthor Krit Pongpirul, MD, PhD, of Chulalongkorn University in Bangkok, Thailand, told Medscape Medical News.

Because ketamine is a vasoconstrictor that impairs shivering, the authors write, it is also "associated with smaller drops in core temperature and is a good choice for patients at risk for hypothermia."

On-site anesthesiologist Richard Harris, BM, BS, FANZCA, from South Australia Health in Adelaide, who is a coauthor of the letter, explained to the rescue divers how to determine whether each child needed more ketamine, how to determine the dose, and how to administer the injection. Most children received a rescue ketamine dose of 2.5 mg/kg in cave chamber 8 after a 350-meter dive, Harris told Medscape Medical News.

The boys' wet suits fit poorly because they had lost weight from being a week without food. In addition, the dive team did not have child-sized face masks. The masks thus had to be tightened as much as possible, and the divers had to regularly check for air bubbles during transit.

Given their sedation, "if the full-face mask fails, then they would drown," Smith said.

Each positive-pressure full-face mask delivered 80% oxygen during transit. Each mask was replaced with a nonrebreather oxygen mask upon arrival at the field hospital. Also, because of how poorly the wet suits fit, "US Air Force and Thai Navy SEAL [personnel] facilitated the wet suit removal to maintain the airway, avoid arrhythmia, as well as to protect cervical spine," Lawthaweesawat said.

The second boy who was rescued developed mild hypothermia, with a body temperature of 34.8° Celsius (94.6° Fahrenheit) on the first day, partly because of inefficient team coordination, lack of adequate preventive measures, and "confusion over the process," Lawthaweesawat said.

The team therefore developed the Thailand Cave Rescue Protocol: airway, breathing, circulation, and hypothermia (ABC+H). An anesthesiologist managed airway and hypothermia while a respirologist and pediatric cardiologist managed breathing and circulation.

During the rescue and en route to the hospital, the team used a cloth blanket, a heater blanket, whole-body foil wrap, and a hair dryer to keep the boys warm. In addition, each patient received "a bolus of 100 ml of warmed 0.9% normal saline, followed by an infusion of 150 to 200 ml per hour until they were hemodynamically stable," the authors write. Personnel checked the boys' temperature every 5 minutes until each boy's temperature was at least 35° Celsius for four consecutive readings.

Smith wondered how the team managed to keep the saline warm enough without the specialized equipment that keeps IV tubing warm, but Lawthaweesawat said the bags were changed quickly enough that little heat was lost during saline administration.

The research letter focuses primarily on hypothermia, although that was just one of many medical concerns the team faced during their impressive rescue effort, Smith told Medscape Medical News. "It was a very technical rescue — the ropes, the rigging, the diving, and then the medical sedation of the patients in their [cocoons]. This was something extraordinary that had never really been done as far as I know," Smith said. "I think this was a good multifactorial approach for patients who aren't able to care for themselves."

Lawthaweesawat told Medscape Medical News that there were several things that he would do differently from the start or would advise other medical teams to do in similar situations in the future.

First, he would set up critical and noncritical processes from the start, including the hypothermia protocol and body temperature monitoring every 5 minutes and daily orientation for all staff members regarding the processes and protocols.

He would also set up an efficient, effective communication process within the rescue effort. During this rescue, for example, the hospital did not have ongoing communication with the on-site staff.

Lawthaweesawat also emphasized the importance of establishing a public communications strategy early on for communicating updates to the press and the public at large. At the time of the rescue, the team withheld the fact that the boys were sedated with ketamine, because they were advised it would be difficult to explain the reasoning to the public. Having strategies in place ahead of time would have been helpful.

Despite the unique, extreme challenges of the rescue, the team was ultimately successful: all the boys and their coach are in good health today and have received mental health counseling.

"Everybody at the field did a great job for their specific expertise with minimal confusing overlaps," Isara told Medscape Medical News. "All doctors tried hard to use their ability, capability, and their specialization in various fields to overcome all obstacles under the limits of time and information."

The authors have disclosed no relevant financial relationships. Smith is president and medical director of Wilderness and Emergency Medicine Consulting, LLC.

N Engl J Med. Published online April 3, 2019. Abstract

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