In December 2015, an Irish Coast Guard rescue helicopter crew located two casualties in cold waters off County Wexford. In heavy swells and close to rocks, a 15-year-old boy was fighting to keep an unconscious 14-year-old girl above the waves. Needing to get them out of danger quickly, the winchman placed strops on both casualties (a ‘hypothermic’ double-loop strop on the girl) so they could be hoisted into the S-92A helicopter hovering overhead. As the pair reached the open door of the aircraft, the unconscious girl fell from the strop back into the sea. A second attempt was quickly made, and this time she was brought onboard and flown with the boy to hospital, arriving less than 20 minutes after the initial call-out.

Aoife Winterlich had been swept into the sea with the boy and two others during a Venture Scout expedition. Two of the four victims managed to clamber out onto rocks. The boy who was plucked from the sea survived, but Winterlich later died in hospital in Dublin. An Irish Coast Guard investigation found the crew had no option but to attempt the simultaneous winch due to the immediate danger of both victims being washed onto the rocks.

the crew had no option but to attempt the simultaneous winch due to the immediate danger of both victims being washed onto the rocks

Ireland’s Air Accident Investigation Unit (AAIU) issued a report on 8 March stating that CHC Ireland, operator of the country’s coast guard helicopters, did not give its crews specific guidelines to use different procedures or equipment for unconscious patients than they would use for conscious casualties. It urged the provider to address this: “CHC Ireland should provide documented guidance to their SAR crews that can be used to assess and address the operational and medical risks associated with winching casualties, whether conscious or unconscious, by use of a helicopter rescue strop.” (AMR 83, April/May 2017, Call for guidance on winching unconscious casualties). The AAIU did not find any evidence of wear, damage or failure of either strop used during the mission.

What might such guidance cover? AMR spoke to providers from around the world, including CHC, to ask what they consider general best practice for winching unconscious casualties.

Physical risks

The simplest rescue sling or strop comprises a loop which passes under a person’s arms and around their back, suspending them from a point above and in front of their head. If the casualty raises their arms, either by choice or involuntarily, they can fall through the loop. Versions are available with features such as non-slip material or the ability to cinch the loop tight on the patient. So-called ‘hypothermic’ strops have two loops – one passes under the arms while the second goes under the legs so the patient can be lifted in a more horizontal position (more on that later). Nonetheless, an uncompliant or unconscious patient can still fall through.

Peter McDonnell, chief crewman for CHC Helicopters’ Australian SAR operations, told AMR that the main issues associated with the recovery of unconscious patients is their inability to maintain their own airway/breathing and the loss of muscle tone. The latter inhibits the casualty’s ability to maintain a constant body position and this can lead to a casualty ‘slipping’ from rescue devices if not restrained appropriately.

hypothermic strops … still allow the patient to fall out if their arms slip out of the strop placed around the torso

Dr Matthias Ruppert is medical director at ADAC Luftrettung of Germany. Of the organisation’s 37 bases, four conduct hoist operations, tallying some 250 to 300 hoist missions per year. He told AMR about some of the risks posed by winching unconscious patients: “The lack of actively holding down the upper extremities makes a sliding of the (wet) body out from any sling very likely if the rescuer does not hold down the patient’s arms. But if the rescuer needs one of his/her arms to do something else (i.e. when approaching the helicopter), he or she may have difficulties securing the patient at the same time.”

Thomas Knudstrup, senior product manager at Lite Flite, Denmark, which manufactures air rescue equipment, commented: “All it takes is a split-second of unawareness from the rescuer (the winchman) – the victim’s arms may raise to a level where there is nothing to keep the victim in the sling. From what we know, such accidents happen a few times each year.”

Brad Matheson, president of search and rescue training specialist Priority 1 Air Rescue (P1AR), added that not only are unconscious patients at greater risk of slipping, but there’s the added problem that they can’t speak up to alert the rescuer if they begin to do so. He mentioned that hypothermic strops provide some additional security, but will still allow the patient to fall out if their arms slip out of the strop placed around the torso. Slipping can be a risk even in compliant, conscious patients, he said, for example if they unwittingly reach up to make a grab for a helicopter skid as they near the aircraft.

Medical risks

Aside from the risks of unconscious casualties slipping out of rescue devices, there are also particular medical risks associated with a patient being unconscious, explained Ruppert, such as further deterioration of airway patency, respiratory function and/or circulatory status, especially in an upright position with an unsecured airway.

Knudstrup explained in layman’s terms why hypothermic victims require particular care: “The blood of a hypothermia victim that is hoisted for just a short time in an upright position may pool up in the victim’s legs, causing lack of blood and oxygen to the brain. When the victim is saved, that is, hoisted into and laid down in the helicopter, all the blood ‘flushes’ through the arteries and veins. This initial drop of blood pressure, followed by a sudden increase of blood pressure, may simply cause the death of the victim. We do not know how often it happens, but foreign studies suggest that this type of death can happen instantly, after a short while or even days after being rescued.”

Double-loop strops have uses beyond hypothermic patients, Peter McDonnell of CHC Australia told AMR: “Personnel on land who may be suffering from minor lower leg injuries … can also be recovered using the hypothermia strop technique.”

Equipment

It’s worth noting that although there are drawbacks, the single-loop strop and double-loop hypothermic strop designs have major plus points – they are simple to store, to deploy and to get onto the casualty. However, Knudstrup warned against overuse of strops: “Every SAR operator will probably look at the traditional rescue sling as a simple-to-use-product, but it really should be the last resort. Modern rescue slings can have as many features [as you can imagine], like self-securing systems, anti-slip rubber … support handles and crotch straps. But whenever possible, try to utilise a rescue device that does not include the risk of slipping.”

If strops have been seen as a go-to option up until now, that’s down to the history of air/sea rescue, said TRS Canada project manager Derek Rogers: “These are legacy items that were initially designed to recover aircrew in ditching or crash situations, not as a medical evacuation devices. Research and court rulings are starting to recognise the limitations of the rescue sling/strop.”

the best case scenario is a land-based open area hoist, with the casualty strapped in a rescue stretcher

Bob Cockell, vice-president at Air Rescue Systems, concurred that collar-type devices are overused, adding: “I’m not saying these devices don’t have their place. They are well made, well thought out and work well for a number of mission/victim profiles. However, the misapplication of these have led to disastrous outcomes for the victims we work so hard to save.” Problems are not limited to unconscious patients – the ‘difficult victim list’ includes the obtunded, hypothermic, wet, elderly, young or obese, said Cockell. He continued: “Add any number of injuries and the use of these devices increase the odds of a potentially negative outcome of the rescue.”

For air rescue crews looking for something more secure, there is a whole range of options available. Commenting on the gold standard where conditions allow, Rogers said: “For recovering an unconscious casualty, the best case scenario is a land-based open area hoist, with the casualty strapped in a rescue stretcher, airway secured and tag-lined during the hoist to limit turbulence and oscillation.”

NSW Ambulance and Toll Helicopters told AMR of the creature comforts that patients on stretchers enjoy: “The aeromedical stretcher has been designed specifically for helicopter winching operations. A tag line (anti-spin line) is used to ensure that the stretcher does not spin under the aircraft whilst being winching up. The tag line is fitted with a release system that can be activated by the NSW Ambulance doctor or paramedic once at aircraft height … head, ear and face protection is provided for the patient as well as a patient thermal winch bag. The custom-designed sleeping bag protects the patient from the elements during the winch.”

However, such stretchers can be difficult to load in the water, said Rogers, and it can be hard to control oscillations if there is no tagline or guideline being used. CHC’s McDonnell commented: “If conditions are such that a stretcher winching extraction is not achievable, other alternates available to crews are ‘fully body harness’ or similar device and the rescue strop.”

Ruppert commented that the majority of unconscious patients hoisted by ADAC are winched in a supine position, not on a stretcher, but on a vacuum mattress in a ‘rescue bag’, while patients with minor injury/sickness are hoisted in a ‘rescue triangle’. However, the organisation’s crews are permitted to use strops in extreme situations such as water rescues or patients in acute danger.

all other possible means of extraction will be considered prior to winching an unconscious patient

Matheson said the primary device P1AR uses for minimising the risk when conducting double-up extractions, or even single-up extractions on the smaller-capacity hoists on light helicopters, is the Ambulatory Victim Extrication Device (AVED). Lite Flite offers a similar solution known as a ‘rescue wrap’, as Knudstrup explained: “A victim who is going to be rescued or evacuated from ship, ground, mountain or another hard surface can, with a lot of benefits, be winched by means of a rescue wrap. Not the triangular shaped model that has been made by several manufacturers for years, but a modern type that is carrying the victim’s weight by the back, giving support to the head and having large supporting wraps around the thighs. Such wraps have been around for a while, but most of them are actually more like soft stretchers, with multiple suspension points and complicated mechanisms.” A carefully designed rescue wrap can be folded and rolled up into a very small package, he added, and is easy to use. Knudstrup continued: “It will keep the victim in the same semi-sitting position as the dual [hypothermic] sling, while the risk of slipping is reduced to almost zero.”

Rogers warned that a rescue vest or jacket used in the water must have been designed for this purpose, or it can effectively become a sea anchor.

Returning to the simple strop design, these can be improved with a crotch strap, said Matheson: “When we employ a strop (for water rescue), we only use the LSC Quick Strop that has an integrated crotch strap to prevent the survivor from slipping out in the event they go unconscious or reach for the skid. Along with this specialised strop, our rescue specialists use a leg scissor and/or modified physical grip to the survivor depending on the type of lift.”

Crotch straps have their own drawbacks, though, said Knudstrup: “The problem with this solution is that a crotch strap may harm the victim, for obvious reasons. This is true, whether the crotch strap is made of narrow webbing or a piece of wide fabric. Anything designed to support the victim between the legs should be designed in a way that does not harm their vital parts.” Other than the additional security, he said, the advantage of a rescue sling equipped with a crotch strap is its suitability for use in water.

Another option, said Matheson, is to use a rescue basket to extricate patients, especially larger individuals or hypothermic casualties. Baskets are routinely used by agencies such as the US Coast Guard, but come with a higher price tag and inevitably take up more space in the helicopter than a strop, even if a collapsible version is chosen.

Rogers noted that a severely hypothermic casualty in the water is one of the most challenging situations a rescuer can face: “In this case, the fastest and most effective recovery method is a simple personnel carrying device such as a rescue basket or Billy Pugh [‘rescue net’]. These devices are easy to use, very fast (limiting under-rotor exposure), can be utilised for passive rescue and offer full support to an unconscious casualty. The only drawback with these items is size and aviation certification.”

Certification of equipment is an issue, said Rogers, and there can be question marks on where the scope of a provider’s air operator certificate is deemed to end – whether it ends at the rescue hook or continues to cover equipment attached to the hook. “Often it is left to the operator to seek approval for a piece of equipment,” he explained, “citing best practices or parallel industry standards. Unfortunately, this leads to older gear (often ‘grandfathered’ into service prior to formal certification) being utilised well beyond its design intent and often redundant compared to modern equipment.”

Procedures

What of specialised procedures, as alluded to in the AAIU’s report on the 2015 incident? McDonnell recognised that clearly defined standard operating procedures are ‘critical’, adding that so too is ensuring the operating crews have the appropriate resources available to them to make informed decisions appropriate to the task at hand: “Having more tools in the tool box, so to speak, with the appropriate training to support them. This has to be balanced with the type of aircraft being operated, the stowage and payload available, along with the operating terrain and environment, but ultimately having the right tools and equipment available to appropriately trained, competent and current crews with a wider support structure of standard operating procedures will assist in minimising the risks to both the casualty and crew.”

Toll Helicopters and NSW Ambulance said they have comprehensive and advanced risk assessment procedures for all operations, particularly winching: “All other possible means of extraction will be considered prior to winching an unconscious patient. Winches only occur if a risk assessment considers that to be the safest option for the air and medical crew and the patient. In some cases, a risk mitigation measure will see the patient transported to a helicopter landing zone and not winched.” The idea that a hoist is in effect a Plan B option was also voiced by Cockell of Air Rescue Systems: “Risk mitigation and a thorough look at all alternatives to hoisting must be of the highest priority. Is a one-kilometre, overland carry-out acceptable vs hoisting? Can transport alternatives be arranged (4X4, ATV, boat etc.)? The team should always be looking for a way not to hoist and must answer the overriding question: ‘Is what we’re doing or planning to do based on convenience or necessity?’.”

Training on procedures is key, said Toll Helicopters and NSW Ambulance: “All air crew and medical crew complete regular stretcher winch rescue training. Formal procedures are in place to ensure familiarity and compliance.” An operator’s procedures should include not only ‘normal’ situations, but also cover what to do in emergencies, advised Knudstrup: “These situations are most likely to put the equipment to the limitations. So if a dual sling is used, make sure that each of the slings can carry the necessary weight.”

be deliberate and slow when bringing the patient and rescuer past the skid

Having a rescuer accompany the casualty during the winch is a widespread practice to enhance safety. Ruppert said that all hoist manoeuvres carried out by ADAC are performed as a ‘double winch’ with the medic being lifted with the patient. Matheson of P1AR concurred: “We would not recommend having a single person riding a strop, especially when they are not trained. If a person who appears OK to ride the strop becomes unconscious due to cardiac or breathing issues related to intrathoracic pressure or cardiac irritability (due to hypothermia), they will fall out of the strop.” He added: “Be deliberate and slow when bringing the patient and rescuer past the skid (as to not hit their head, and ensuring the rescuer has time to prevent the patient from reaching for the skid), and always use a safety (Orca) strap when transitioning into or out of the cabin during hoisting.”

In the case of river, lake or coastal rescues, Ruppert said that ADAC (which does not perform offshore missions) does use a rescue strop, but minimises the risk of falling by carrying the patient just a few metres above the water to the nearest bank, shore or beach, rather than attempting to bring them up to the helicopter.

Ultimately, though, it is difficult to give a definitive answer on best practice for unconscious casualty hoist procedures. Rogers of TRS Canada noted that there is a lack of established, evidence-based research in this area, a gap his organisation is trying to fill. He said: “Working with the support of HNZ Helicopters, we’ve tested a number of recovery systems in our full-effects synthetic hoist trainer at the SSTL facility in Halifax, Nova Scotia, Canada. Our informal research has confirmed that the rescue basket is the quickest and safest emergency recovery device for unconscious casualties in adverse water conditions. Unfortunately, formal research is limited on this issue and many of our procedures are opinion versus evidence-based – rest assured we are working to address this gap along with many others in the industry.”

Cockell of Air Rescue Systems added that rescuers should stay open to new methods: “Don’t base your operational mode solely on ‘it’s what we’ve always done’. There is always an alternative to every action. Seek input from other teams. Network with your peers and remain open to ideas, even those outside of your organisation’s cultural norms and experiences. Look at those missions which did not go as planned, the ones that left you feeling you could have performed better, the ones where you really couldn’t put a finger on the problem, but you knew it wasn’t 100 per cent.”.