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Unattended Hoist Extraction of an Intubated Patient From Mountainous Terrain
ARTICLE IN PRESS Air Medical Journal 000 (2020) 1−4
Contents lists available at ScienceDirect
Air Medical Journal journal homepage: http://www.airmedicaljournal.com/
Case Report
Unattended Hoist Extraction of an Intubated Patient From Mountainous Terrain Miles J. McDonough, BA, EMT-B 1,2,*, Richard O. Duncan, BS, EMT-P 1,3, Ronald L. Brown, MD 1,3,4, Andrew M. Luks, MD 5, Anna E. Condino, MD, MPH 6 1
Snohomish County Helicopter Rescue Team, Snohomish, WA University of Washington School of Medicine, Seattle, WA Snohomish County Fire District #26, Gold Bar, WA 4 North Sound Emergency Medicine, Everett, WA 5 Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, WA 6 Department of Emergency Medicine, University of Washington, Seattle, WA 2 3
A B S T R A C T
Airway management and maintenance of adequate ventilation during a patient’s unattended helicopter rescue hoist extraction present unique challenges to the air medical provider. We present the case of a critically injured patient requiring emergent airway management and subsequent extrication via hoist from challenging, near-vertical terrain, which illustrates the logistical challenges of providing high-quality, neuroprotective mechanical ventilation in an austere air medical scenario. © 2020 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.
Case Report A 23-year-old man was attempting a rock climbing route on a 1,000-ft tall cliff in Washington state when he fell approximately 50 ft, sustaining suspected traumatic brain injury (TBI). After a 911 call, the Washington State Emergency Operations Center dispatched a hoistequipped Bell UH-1H plus 703 helicopter with a county-based, helicopter rescue team from 70 miles away directly to the patient’s coordinates, partway up the cliff at an approximate elevation of 3,000 ft. The rescue helicopter established in a hover above the accident site, allowing the rescue technician (an emergency medical technician−basic [EMT-B]), flight paramedic (an emergency medical technician−paramedic), and rescue gear to be hoist inserted approximately 100 ft downslope of the patient, who was suspended in his harness in 70-degree, rocky terrain. Shortly after insertion, the rescue technician and advanced life support−trained flight paramedic were met by 2 members of a ground search and rescue team climbing up from below that included an additional paramedic. Together the rescuers scrambled the remaining distance to access the patient’s location. The primary assessment revealed an unconscious, unresponsive patient with upper extremity decorticate posturing and a right periorbital hematoma. Airway evaluation revealed trismus with a 1-cm *Address for correspondence: Miles J. McDonough, BA, EMT-B, 5203 38th Avenue NE, Seattle, WA 98105 E-mail address: [email protected] (M.J. McDonough). 1067-991X/$36.00 © 2020 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.amj.2020.01.006
gap between the incisors. His breathing pattern was tachypneic and irregular with low tidal volumes. His Glasgow Coma Scale score was determined to be 5 (E1 V1 M3). The flight paramedic on scene determined that immediate airway management was indicated but would require moving the patient to a flatter spot on the ledge where the patient had come to rest, a horizontal distance of approximately 6 ft away. This was accomplished by securing the patient to a new anchor and then cutting him free of his climbing rope and sliding him across the ledge. Once secured in the new position, oxygen was provided via a nonrebreather mask. The initial vital signs taken at that time included a blood pressure of 180/62 mm Hg, a heart rate of 70 beats/min, and a respiratory rate of 28 breaths/min. Intravenous access was obtained via an 18-G peripheral intravenous line in the left antecubital fossa. After the administration of etomidate 20 mg intravenously and succinylcholine 100 mg intravenously, the trachea was intubated with a 7.5-mm endotracheal tube via direct laryngoscopy on the first attempt, maintaining manual in-line cervical spine stabilization. The patient was initially ventilated using a Pocket Bag Valve Mask (Micro BVM Systems Ltd, Jerusalem, Israel) targeting an end-tidal carbon dioxide tension (PETCO2) of 35 mm Hg using the EMMA Mainstream Capnometer (Masimo, Irvine, CA). The endotracheal tube was secured at 24 cm at the teeth (Thomas Endotracheal Tube Holder; Laerdal Medical, Stavanger, Norway), and the patient was then placed on a Pneupac VR1 pneumatic ventilator (Smiths Medical, Minneapolis, MN)
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Figure 1. Demonstration of patient packaging in litter with ventilator and oxygen cylinder secured under litter straps. Figure 3. Demonstration of secured endotracheal tube and capnometer with bag valve mask and oropharyngeal airway adjunct nearby.
Figure 2. Demonstration of patient fully packaged in Bauman Bag prior to hoist extraction.
using a fraction of inspired oxygen (FiO2I) of 1.0, a tidal volume of 500 mL, and a respiratory rate of 10 breaths/min; 70 mg rocuronium was administered to ensure continued neuromuscular blockade during hoist extraction to the aircraft. After the initial care discussed previously, the patient was subsequently secured in a litter and then placed into a Baumann Bag (CMC Rescue, Goleta, CA) for hoist extraction. The oxygen cylinder (DD Lite Carbon Fiber; Ferno International, Wilmington, OH) was placed between the patient’s legs, and the ventilator was positioned on the patient’s torso, both of which were secured with litter straps inside the Bauman Bag (Fig. 1). Before hoisting, the ventilator was confirmed to be functional with the intended FiO2 and a PETCO2 of 31 mm Hg. After packaging, the rescuers radioed the helicopter, which had left to refuel, and requested they return to extract the patient and rescuers (Fig. 2). The positioning of the endotracheal tube was verified immediately before the flight paramedic leaving the patient’s side to be hoisted into the aircraft and then again immediately once the patient was received in the aircraft. The risk of the endotracheal tube being dislodged during this time was addressed by having the patient fully packaged and secured in both the litter and the Bauman Bag. Cervical spine stabilization was achieved with a rigid cervical collar. During this time, the rescue technician/EMT-B on the ground with the patient was alert for the alarm from the EMMA Mainstream Capnometer indicating apnea. Should the alarm sound the EMT-B was directed to recall the paramedic to the ground and was prepared to attempt ventilation with the bag valve mask in place of the ventilator. Should the alarm persist, the EMT-B was prepared to extubate the patient and begin ventilation with an oropharyngeal airway and a bag valve mask (Fig. 3). In this particular rescue, a second paramedic who had hiked to the patient’s location was available on the ground to mitigate any airway issues until the patient was hoisted to the aircraft.
Figure 4. Hoist extraction of flight paramedic.
Figure 5. Hoist extraction of Bauman Bag with tag line attached to limit rotation.
The extraction was completed in 4 successive hoist iterations over a 10-minute period. The flight paramedic and then the remaining gear were hoist extracted during the first 2 iterations (Fig. 4). With the gear stowed and the flight paramedic positioned in the helicopter, the patient was transferred from the rock anchor to the helicopter hoist cable. The rescue technician, still anchored to the rock wall, provided tension through a tag line attached at the foot of the Bauman Bag to limit patient rotation during the 120-ft hoist extraction (Fig. 5). Once the patient was on board the aircraft (Fig. 6), endotracheal tube positioning was verified, and the PETCO2 measured 30 mm Hg. The rescue technician was then hoisted into the helicopter to assist with patient care during the 36-minute flight (Fig. 7). During flight, midazolam, 5 mg intravenously, was administered twice, proximal humeral head intraosseous vascular access was obtained, and the oropharynx was suctioned of approximately 20 mL blood. The patient remained hemodynamically stable
ARTICLE IN PRESS M.J. McDonough et al. / Air Medical Journal 00 (2020) 1−4
Figure 6. Crew chief sliding Bauman Bag to flight paramedic positioned inside the helicopter.
Figure 7. Hoist extraction of rescue technician.
in flight and was delivered to a level I trauma center in Seattle, 78 miles from the accident site, 3.5 hours after the helicopter was initially dispatched. Hospital Course On arrival to the emergency department, the patient was intubated and sedated with a blood pressure of 109/52 mm Hg, heart rate of 56 beats/min, respiratory rate of 17 breaths/min, and SpO2 of 100% on FiO2 of 50%. The initial head computed tomographic scan of the brain revealed subarachnoid hemorrhage and trace pneumocephalus without herniation or mass effect. Additional imaging revealed multiple craniofacial fractures and a left medial malleolus fracture. There were no intrathoracic, abdominal, or pelvic solid organ or additional orthopedic injuries. The patient was admitted to the neurosciences intensive care unit. A subarachnoid bolt and Licox monitor (Integra Life Sciences, Saint Priest, France) were placed on the right side of his head for continuous monitoring of intracranial pressure and brain tissue partial pressure of oxygen, which were removed after 4 days. He did not require operative intervention for any of his injuries. Magnetic resonance imaging of the brain was obtained on the fourth hospital day and revealed diffuse axonal injury with multiple foci of microhemorrhage in the bilateral cerebral hemispheres, corpus callosum, and brainstem. His subsequent hospital course was complicated by recurrent pneumonia and persistent respiratory failure requiring a tracheotomy and percutaneous endoscopic gastrostomy tube. He was eventually liberated from the ventilator; his tracheostomy was decannulated; and after 36 days in the hospital, he was discharged to an acute inpatient rehabilitation facility. Discussion Although helicopters provide expedited access to remote emergency sites, mountainous terrain often lacks suitable landing zones for traditional helicopter emergency medical services (HEMS) resources.
3
Helicopters equipped with human external cargo (HEC) equipment, such as rescue hoists or short-haul fixed lines, provide rescuers and emergency medical personnel a means to access patients stranded in such situations. The alternative to HEC in remote, wilderness settings involves the time- and labor-intensive process of carrying the subject over rugged terrain, often with the assistance of technical rope rescue, to either a landing zone accessible to HEMS resources or a location accessible by ground-based emergency medical services. Helicopter evacuation is often a considerably faster method of extrication according to a retrospective study of rescues in the United Kingdom. This study showed that for patients who required transport greater than 400 m through remote terrain to a landing zone, HEC-equipped HEMS would have reduced prehospital time in 34% of cases.1 The extrication of an intubated patient from technical terrain using HEC is an infrequent scenario. For example, in a retrospective analysis of 125 rescues requiring HEC between 2010 and 2014 in Australia, none of the extricated patients required intubation.2 A comprehensive review of advanced airway management preceding HEC evacuations identified 34 patients documented over 17 years in 5 articles and 1 case study.3 Given this small cohort of patients, those authors concluded that more data were needed before generating evidence-based recommendations for the management of such situations. The Snohomish County Helicopter Rescue Team developed and refined a protocol that uses a lightweight ventilator (Pneupac VR1), which is battery free, powered by compressed oxygen, and equipped with capnography (EMMA Mainstream Capnometer). Together the ventilator and capnometer weigh approximately 17 oz. Both the ventilator and oxygen cylinder are secured inside the Bauman Bag with the littered patient. Automated ventilation systems have been shown to be superior in providing controlled, consistent, and reliable ventilation during hoist operations compared with manual ventilation.4 Because many helicopter rescue teams limit the hoist cable load to a single individual (patient or rescuer) per hoist extraction, the maintenance of adequate oxygenation and ventilation is a critical task because a rescuer is not available during the extraction to monitor the ventilator or provide ventilations with a bag valve mask. Even if hoist systems are capable of multiperson hoists, the medical provider’s ability to assess and/or modify treatments while connected to the hoist is negligible because of rotor wash, patient packaging, and his or her attachment point in relation to the patient’s airway. Between the time the paramedic left the ground en route to the aircraft and the arrival of the patient after the subsequent hoist iteration, the patient was separated from the advanced life support −trained flight paramedic for just under 6 minutes. Although basic life support−trained rescue technicians can provide bag valve mask ventilation, they are not trained to manage the airway of an intubated patient should a complication arise. The likelihood of such complications over the short period of time required for hoist extraction may be low, but if the helicopter was forced to abort during the extraction sequence because of a change in visibility, mechanical issue, hoist cable malfunction, or other problems, the basic life support technician would be stranded with an intubated patient. In this scenario, another ground paramedic was available, but this may not always be the case. The ability to maintain a patent airway, oxygenation, and ventilation is critically important in TBI because outcomes reflect not only the effects of the original injury but also the effects of secondary injury caused by hypotension, hypoxemia, and hypercarbia.5 Although prior research has not shown a survival advantage for patients with moderate to severe TBI intubated in the prehospital setting versus the emergency department,6 prehospital advanced airway management on outcomes in TBI remains controversial, particularly in remote field settings. The alternative to endotracheal intubation in the field is bag valve mask or supraglottic airway management, with the assumption that the provider is positioned to
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observe and assist in maintaining the patient’s airway at all times. However, with HEMS hoist extraction, the ability to provide patient care, including bag valve mask ventilation, is fundamentally limited by rotor wash7 and restricted patient access. As a result, when helicopter-based extraction is required, invasive mechanical ventilation may be superior to manual ventilation4,8 because it greatly increases the odds of maintaining airway patency as well as adequate oxygenation and ventilation during the entire extraction process. Conclusions Airway management of critically injured patients in steep mountainous terrain is a high-risk endeavor that nonetheless can be accomplished successfully with thoughtful protocols and expert execution. All search and rescue teams, HEMS and ground, must be prepared to secure an advanced airway and maintain oxygenation and ventilation after intubation, especially if a helicopter hoist or short haul will render the patient unattended for any significant amount of time.
References 1. Ellerton J, Gilbert H. Should helicopters have a hoist or ‘long-line’ capability to perform mountain rescue in the UK? Emerg Med J. 2012;29:56. 2. Meadley B, Heschl S, Andrew E, de Wit A, Bernard SA, Smith K. A paramedic-staffed helicopter emergency medical service’s response to winch missions in Victoria, Australia. Prehosp Emerg Care. 2016;20:106–110. 3. Pietsch U, Knapp J, Kreuzer O, et al. Advanced airway management in hoist and longline operations in mountain HEMS−considerations in austere environments: a narrative review This review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand J Trauma Resusc Emerg Med. 2018;26:23. 4. Hollott J. Ventilatory choices for intubated patients during helicopter stretcher winching: ventilation during intubated stretcher winching. Emerg Med Australas. 2017;29:692–696. 5. Chesnut RM, Marshall LF, Klauber MR, Blunt BA. The role of secondary brain injury in determining outcome from severe head injury. J Trauma. 1993;34:216–222. 6. Lansom JD, Curtis K, Goldsmith H, Tzannes A. The effect of prehospital intubation on treatment times in patients with suspected traumatic brain injury. Air Med J. 2016; 35:295–300. 7. Burns BJ, Edwards K, House T. Bag valve mask failure during HEMS intubated stretcher winch. Air Med J. 2012;31:84–86. 8. Lavon O, Hershko D, Barenboim E. The utility of flow-limited automated mechanical ventilation during airborne hoist rescue missions. Am J Emerg Med. 2010;28:523– 526.
Contents lists available at ScienceDirect
Air Medical Journal journal homepage: http://www.airmedicaljournal.com/
Case Report
Unattended Hoist Extraction of an Intubated Patient From Mountainous Terrain Miles J. McDonough, BA, EMT-B 1,2,*, Richard O. Duncan, BS, EMT-P 1,3, Ronald L. Brown, MD 1,3,4, Andrew M. Luks, MD 5, Anna E. Condino, MD, MPH 6 1
Snohomish County Helicopter Rescue Team, Snohomish, WA University of Washington School of Medicine, Seattle, WA Snohomish County Fire District #26, Gold Bar, WA 4 North Sound Emergency Medicine, Everett, WA 5 Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, WA 6 Department of Emergency Medicine, University of Washington, Seattle, WA 2 3
A B S T R A C T
Airway management and maintenance of adequate ventilation during a patient’s unattended helicopter rescue hoist extraction present unique challenges to the air medical provider. We present the case of a critically injured patient requiring emergent airway management and subsequent extrication via hoist from challenging, near-vertical terrain, which illustrates the logistical challenges of providing high-quality, neuroprotective mechanical ventilation in an austere air medical scenario. © 2020 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.
Case Report A 23-year-old man was attempting a rock climbing route on a 1,000-ft tall cliff in Washington state when he fell approximately 50 ft, sustaining suspected traumatic brain injury (TBI). After a 911 call, the Washington State Emergency Operations Center dispatched a hoistequipped Bell UH-1H plus 703 helicopter with a county-based, helicopter rescue team from 70 miles away directly to the patient’s coordinates, partway up the cliff at an approximate elevation of 3,000 ft. The rescue helicopter established in a hover above the accident site, allowing the rescue technician (an emergency medical technician−basic [EMT-B]), flight paramedic (an emergency medical technician−paramedic), and rescue gear to be hoist inserted approximately 100 ft downslope of the patient, who was suspended in his harness in 70-degree, rocky terrain. Shortly after insertion, the rescue technician and advanced life support−trained flight paramedic were met by 2 members of a ground search and rescue team climbing up from below that included an additional paramedic. Together the rescuers scrambled the remaining distance to access the patient’s location. The primary assessment revealed an unconscious, unresponsive patient with upper extremity decorticate posturing and a right periorbital hematoma. Airway evaluation revealed trismus with a 1-cm *Address for correspondence: Miles J. McDonough, BA, EMT-B, 5203 38th Avenue NE, Seattle, WA 98105 E-mail address: [email protected] (M.J. McDonough). 1067-991X/$36.00 © 2020 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.amj.2020.01.006
gap between the incisors. His breathing pattern was tachypneic and irregular with low tidal volumes. His Glasgow Coma Scale score was determined to be 5 (E1 V1 M3). The flight paramedic on scene determined that immediate airway management was indicated but would require moving the patient to a flatter spot on the ledge where the patient had come to rest, a horizontal distance of approximately 6 ft away. This was accomplished by securing the patient to a new anchor and then cutting him free of his climbing rope and sliding him across the ledge. Once secured in the new position, oxygen was provided via a nonrebreather mask. The initial vital signs taken at that time included a blood pressure of 180/62 mm Hg, a heart rate of 70 beats/min, and a respiratory rate of 28 breaths/min. Intravenous access was obtained via an 18-G peripheral intravenous line in the left antecubital fossa. After the administration of etomidate 20 mg intravenously and succinylcholine 100 mg intravenously, the trachea was intubated with a 7.5-mm endotracheal tube via direct laryngoscopy on the first attempt, maintaining manual in-line cervical spine stabilization. The patient was initially ventilated using a Pocket Bag Valve Mask (Micro BVM Systems Ltd, Jerusalem, Israel) targeting an end-tidal carbon dioxide tension (PETCO2) of 35 mm Hg using the EMMA Mainstream Capnometer (Masimo, Irvine, CA). The endotracheal tube was secured at 24 cm at the teeth (Thomas Endotracheal Tube Holder; Laerdal Medical, Stavanger, Norway), and the patient was then placed on a Pneupac VR1 pneumatic ventilator (Smiths Medical, Minneapolis, MN)
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Figure 1. Demonstration of patient packaging in litter with ventilator and oxygen cylinder secured under litter straps. Figure 3. Demonstration of secured endotracheal tube and capnometer with bag valve mask and oropharyngeal airway adjunct nearby.
Figure 2. Demonstration of patient fully packaged in Bauman Bag prior to hoist extraction.
using a fraction of inspired oxygen (FiO2I) of 1.0, a tidal volume of 500 mL, and a respiratory rate of 10 breaths/min; 70 mg rocuronium was administered to ensure continued neuromuscular blockade during hoist extraction to the aircraft. After the initial care discussed previously, the patient was subsequently secured in a litter and then placed into a Baumann Bag (CMC Rescue, Goleta, CA) for hoist extraction. The oxygen cylinder (DD Lite Carbon Fiber; Ferno International, Wilmington, OH) was placed between the patient’s legs, and the ventilator was positioned on the patient’s torso, both of which were secured with litter straps inside the Bauman Bag (Fig. 1). Before hoisting, the ventilator was confirmed to be functional with the intended FiO2 and a PETCO2 of 31 mm Hg. After packaging, the rescuers radioed the helicopter, which had left to refuel, and requested they return to extract the patient and rescuers (Fig. 2). The positioning of the endotracheal tube was verified immediately before the flight paramedic leaving the patient’s side to be hoisted into the aircraft and then again immediately once the patient was received in the aircraft. The risk of the endotracheal tube being dislodged during this time was addressed by having the patient fully packaged and secured in both the litter and the Bauman Bag. Cervical spine stabilization was achieved with a rigid cervical collar. During this time, the rescue technician/EMT-B on the ground with the patient was alert for the alarm from the EMMA Mainstream Capnometer indicating apnea. Should the alarm sound the EMT-B was directed to recall the paramedic to the ground and was prepared to attempt ventilation with the bag valve mask in place of the ventilator. Should the alarm persist, the EMT-B was prepared to extubate the patient and begin ventilation with an oropharyngeal airway and a bag valve mask (Fig. 3). In this particular rescue, a second paramedic who had hiked to the patient’s location was available on the ground to mitigate any airway issues until the patient was hoisted to the aircraft.
Figure 4. Hoist extraction of flight paramedic.
Figure 5. Hoist extraction of Bauman Bag with tag line attached to limit rotation.
The extraction was completed in 4 successive hoist iterations over a 10-minute period. The flight paramedic and then the remaining gear were hoist extracted during the first 2 iterations (Fig. 4). With the gear stowed and the flight paramedic positioned in the helicopter, the patient was transferred from the rock anchor to the helicopter hoist cable. The rescue technician, still anchored to the rock wall, provided tension through a tag line attached at the foot of the Bauman Bag to limit patient rotation during the 120-ft hoist extraction (Fig. 5). Once the patient was on board the aircraft (Fig. 6), endotracheal tube positioning was verified, and the PETCO2 measured 30 mm Hg. The rescue technician was then hoisted into the helicopter to assist with patient care during the 36-minute flight (Fig. 7). During flight, midazolam, 5 mg intravenously, was administered twice, proximal humeral head intraosseous vascular access was obtained, and the oropharynx was suctioned of approximately 20 mL blood. The patient remained hemodynamically stable
ARTICLE IN PRESS M.J. McDonough et al. / Air Medical Journal 00 (2020) 1−4
Figure 6. Crew chief sliding Bauman Bag to flight paramedic positioned inside the helicopter.
Figure 7. Hoist extraction of rescue technician.
in flight and was delivered to a level I trauma center in Seattle, 78 miles from the accident site, 3.5 hours after the helicopter was initially dispatched. Hospital Course On arrival to the emergency department, the patient was intubated and sedated with a blood pressure of 109/52 mm Hg, heart rate of 56 beats/min, respiratory rate of 17 breaths/min, and SpO2 of 100% on FiO2 of 50%. The initial head computed tomographic scan of the brain revealed subarachnoid hemorrhage and trace pneumocephalus without herniation or mass effect. Additional imaging revealed multiple craniofacial fractures and a left medial malleolus fracture. There were no intrathoracic, abdominal, or pelvic solid organ or additional orthopedic injuries. The patient was admitted to the neurosciences intensive care unit. A subarachnoid bolt and Licox monitor (Integra Life Sciences, Saint Priest, France) were placed on the right side of his head for continuous monitoring of intracranial pressure and brain tissue partial pressure of oxygen, which were removed after 4 days. He did not require operative intervention for any of his injuries. Magnetic resonance imaging of the brain was obtained on the fourth hospital day and revealed diffuse axonal injury with multiple foci of microhemorrhage in the bilateral cerebral hemispheres, corpus callosum, and brainstem. His subsequent hospital course was complicated by recurrent pneumonia and persistent respiratory failure requiring a tracheotomy and percutaneous endoscopic gastrostomy tube. He was eventually liberated from the ventilator; his tracheostomy was decannulated; and after 36 days in the hospital, he was discharged to an acute inpatient rehabilitation facility. Discussion Although helicopters provide expedited access to remote emergency sites, mountainous terrain often lacks suitable landing zones for traditional helicopter emergency medical services (HEMS) resources.
3
Helicopters equipped with human external cargo (HEC) equipment, such as rescue hoists or short-haul fixed lines, provide rescuers and emergency medical personnel a means to access patients stranded in such situations. The alternative to HEC in remote, wilderness settings involves the time- and labor-intensive process of carrying the subject over rugged terrain, often with the assistance of technical rope rescue, to either a landing zone accessible to HEMS resources or a location accessible by ground-based emergency medical services. Helicopter evacuation is often a considerably faster method of extrication according to a retrospective study of rescues in the United Kingdom. This study showed that for patients who required transport greater than 400 m through remote terrain to a landing zone, HEC-equipped HEMS would have reduced prehospital time in 34% of cases.1 The extrication of an intubated patient from technical terrain using HEC is an infrequent scenario. For example, in a retrospective analysis of 125 rescues requiring HEC between 2010 and 2014 in Australia, none of the extricated patients required intubation.2 A comprehensive review of advanced airway management preceding HEC evacuations identified 34 patients documented over 17 years in 5 articles and 1 case study.3 Given this small cohort of patients, those authors concluded that more data were needed before generating evidence-based recommendations for the management of such situations. The Snohomish County Helicopter Rescue Team developed and refined a protocol that uses a lightweight ventilator (Pneupac VR1), which is battery free, powered by compressed oxygen, and equipped with capnography (EMMA Mainstream Capnometer). Together the ventilator and capnometer weigh approximately 17 oz. Both the ventilator and oxygen cylinder are secured inside the Bauman Bag with the littered patient. Automated ventilation systems have been shown to be superior in providing controlled, consistent, and reliable ventilation during hoist operations compared with manual ventilation.4 Because many helicopter rescue teams limit the hoist cable load to a single individual (patient or rescuer) per hoist extraction, the maintenance of adequate oxygenation and ventilation is a critical task because a rescuer is not available during the extraction to monitor the ventilator or provide ventilations with a bag valve mask. Even if hoist systems are capable of multiperson hoists, the medical provider’s ability to assess and/or modify treatments while connected to the hoist is negligible because of rotor wash, patient packaging, and his or her attachment point in relation to the patient’s airway. Between the time the paramedic left the ground en route to the aircraft and the arrival of the patient after the subsequent hoist iteration, the patient was separated from the advanced life support −trained flight paramedic for just under 6 minutes. Although basic life support−trained rescue technicians can provide bag valve mask ventilation, they are not trained to manage the airway of an intubated patient should a complication arise. The likelihood of such complications over the short period of time required for hoist extraction may be low, but if the helicopter was forced to abort during the extraction sequence because of a change in visibility, mechanical issue, hoist cable malfunction, or other problems, the basic life support technician would be stranded with an intubated patient. In this scenario, another ground paramedic was available, but this may not always be the case. The ability to maintain a patent airway, oxygenation, and ventilation is critically important in TBI because outcomes reflect not only the effects of the original injury but also the effects of secondary injury caused by hypotension, hypoxemia, and hypercarbia.5 Although prior research has not shown a survival advantage for patients with moderate to severe TBI intubated in the prehospital setting versus the emergency department,6 prehospital advanced airway management on outcomes in TBI remains controversial, particularly in remote field settings. The alternative to endotracheal intubation in the field is bag valve mask or supraglottic airway management, with the assumption that the provider is positioned to
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observe and assist in maintaining the patient’s airway at all times. However, with HEMS hoist extraction, the ability to provide patient care, including bag valve mask ventilation, is fundamentally limited by rotor wash7 and restricted patient access. As a result, when helicopter-based extraction is required, invasive mechanical ventilation may be superior to manual ventilation4,8 because it greatly increases the odds of maintaining airway patency as well as adequate oxygenation and ventilation during the entire extraction process. Conclusions Airway management of critically injured patients in steep mountainous terrain is a high-risk endeavor that nonetheless can be accomplished successfully with thoughtful protocols and expert execution. All search and rescue teams, HEMS and ground, must be prepared to secure an advanced airway and maintain oxygenation and ventilation after intubation, especially if a helicopter hoist or short haul will render the patient unattended for any significant amount of time.
References 1. Ellerton J, Gilbert H. Should helicopters have a hoist or ‘long-line’ capability to perform mountain rescue in the UK? Emerg Med J. 2012;29:56. 2. Meadley B, Heschl S, Andrew E, de Wit A, Bernard SA, Smith K. A paramedic-staffed helicopter emergency medical service’s response to winch missions in Victoria, Australia. Prehosp Emerg Care. 2016;20:106–110. 3. Pietsch U, Knapp J, Kreuzer O, et al. Advanced airway management in hoist and longline operations in mountain HEMS−considerations in austere environments: a narrative review This review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand J Trauma Resusc Emerg Med. 2018;26:23. 4. Hollott J. Ventilatory choices for intubated patients during helicopter stretcher winching: ventilation during intubated stretcher winching. Emerg Med Australas. 2017;29:692–696. 5. Chesnut RM, Marshall LF, Klauber MR, Blunt BA. The role of secondary brain injury in determining outcome from severe head injury. J Trauma. 1993;34:216–222. 6. Lansom JD, Curtis K, Goldsmith H, Tzannes A. The effect of prehospital intubation on treatment times in patients with suspected traumatic brain injury. Air Med J. 2016; 35:295–300. 7. Burns BJ, Edwards K, House T. Bag valve mask failure during HEMS intubated stretcher winch. Air Med J. 2012;31:84–86. 8. Lavon O, Hershko D, Barenboim E. The utility of flow-limited automated mechanical ventilation during airborne hoist rescue missions. Am J Emerg Med. 2010;28:523– 526.