GREATER SYDNEY AREA HEMS PREHOSPITAL EMERGENCY ANAESTHESIA MANUAL VERSION 2.2 JAN 2016 KAREL HABIG, CLIFF REID, BERNIE HANHRAHAN VERSION 2.2 EDITED BY ROB CONWAY 1 GREATER SYDNEY AREA HEMS PREHOSPITAL EMERGENCY ANAESTHESIA MANUAL FOREWORD Advanced airway management, including emergency anaesthesia, is a fundamental component of advanced prehospital care. Securing airway patency and protection is an essential skill in caring for the multiply injured patient. It maximises oxygenation of critically injured patients, enables their safe transport to hospital, facilitates neuroprotection as well as rapid in-hospital investigation and surgical care. The extra time spent on scene securing an airway (even by skilled clinicians) is one of the greatest controversies in prehospital care1. The time spent managing the airway is offset by the time saved during the transport and in-hospital phases of resuscitation as long as it is performed safely and expeditiously. Prehospital emergency anaesthesia scene times of less than 20min are achievable and should be the target during training. Prehospital, Emergency, Anaesthesia, Allows,expedited, Maximises, in>hospital, Oxygena7on, inves7ga7ons, Facilitates,safe, Neuroprotec7on, transfer, Prehospital emergency anaesthesia is potentially riskier than in-hospital general anaesthesia because of the challenges presented by the prehospital environment and therefore every effort must be made to ensure the safety of the procedure. In aviation and military settings it is well accepted, that the higher the acuity of the situation, the greater the need to remove individual procedural preference and the greater the need to adhere to a standard operating procedure. AIMS This manual describes the indications for as well as the procedures to be followed for prehospital emergency anaesthesia. The underlying philosophy is to promote a pre-planned laryngoscopy strategy for first look success. This avoids prolonged and multiple attempts and consequent complications. It aims to ensure a safe standardised technique for prehospital emergency anaesthesia while acknowledging the varied circumstances, environments and pathologies encountered in the prehospital setting. The advice given is derived from the combined experience of a large range of clinicians in prehospital trauma care and is evidence-based where possible. The manual outlines the key theoretical and practical competencies which are assessed in the Emergency Anaesthesia Clinical Currency. Note: This manual describes a system for prehospital emergency anaesthesia; however, many of the principles may be translated directly to in-hospital practice, particularly in skill- or resource-limited settings where retrieval team equipment and expertise may be required to provide the safest and most expedient advanced airway management. 2 INDICATIONS FOR EMERGENCY ANAESTHESIA As with all procedures, the decision to proceed with prehospital emergency anaesthesia must be based on an informed assessment of the risk of the procedure versus the clinical benefits. The indications for prehospital emergency anaesthesia are: Failure(of(airway(patency(, Failure(of(airway(protec1on, Failure(of(ven1la1on(or(oxygena1on, An1cipated(clinical(course(/(humanitarian(reasons, To(facilitate(safe(transporta1on, FAILURE OF AIRWAY PATENCY. Although simple airway manoeuvres and adjuncts such as ear-to-sternal notch positioning, airway suctioning, chin- lift, oropharyngeal and nasopharyngeal airways may be essential initial measures to open and maintain a non-patent airway, these should be regarded as temporising measures. All patient with non-patent airways will require a secure airway at some point in their resuscitation and ideally this should be performed as soon as possible in the prehospital phase provided it can be done safely and expeditiously. FAILURE OF AIRWAY PROTECTION. An unconscious patient with an easily maintained airway and adequate ventilation is still at significant risk of passive regurgitation and aspiration of stomach contents, secretions or blood, particularly if transport times to hospital are prolonged. A patient with an unprotected airway is best defined by their inability to prevent aspiration of secretions, blood or vomitus and is indicated by an absence of spontaneous swallowing and/or failure to spontaneously clear blood, saliva or mucous from the oropharynx. Lack of a gag reflex or GCS <9 as described by EMST/ATLS2 or even GCS motor scores (<4) CANNOT be relied upon as the sole indicator of the need for intubation. FAILURE OF VENTILATION OR OXYGENATION. Patients with acute ventilatory failure or failure to maintain adequate oxygen saturation despite supplemental oxygen should be considered for prehospital emergency anaesthesia and intubation. Such patients may have diminished respiratory drive due to head injury or critical chest injuries impairing ventilation. Early intubation is desirable in such patients. ANTICIPATED CLINICAL COURSE OR HUMANITARIAN REASONS. This indication refers to the patient who can be predicted to deteriorate (e.g. head injuries, inhalational burns or spinal injuries) or where emergency anaesthesia will be important in removing the work of breathing in the face of multiple major injuries. In the case of major trauma patients, whose management is certain to include a complex and potentially painful series of procedures and diagnostic evaluations as well as the operating theatre, early anaesthesia and intubation should be considered. 3 TO FACILITATE SAFE TRANSPORTATION. A sub-group of patients will require emergency anaesthesia to ensure safe transportation particularly in rotary- winged or fixed-wing aircraft and/or where transport times are prolonged. These patients include agitated or uncooperative head injured patients or those with severe psychiatric disturbance. DECISION TO INTUBATE The decision to induce anaesthesia and perform intubation is a medical team decision taking the following factors into consideration3: Factors(in(favour(of(on<scene( emergency(anaesthesia, • Impaired,airway,maintenance,and/or,protec7on, • Hypoxaemia,or,hypoven7la7on,,or,hyperven7la7on, in,pa7ents,requiring,neuroprotec7on, • Fluctua7ng,or,deteriora7ng,level,of,consciousness, • Thermal,injury,to,airway, • Penetra7ng,neck,injury, • Long,road,or,air,transfer,with,risk,of,deteriora7on, • Polytrauma,with,requirement,for,mul7ple, interven7ons,and/or,opera7ve,procedures, • Comba7veness, • High,cervical,lesion,with,diaphragma7c,breathing, Factors(against(on<scene(emergency( anaesthesia, • Morphology,or,pathology,that,may,hinder,successful, intuba7on,(e.g.,laryngeal,fracture,,morbid,obesity), • Time,cri7cal,surgical,lesion,(e.g.,penetra7ng,trauma, with,shock), • Short,distance,from,most,appropriate,hospital, • Hos7le,environment, • Unconducive,team,dynamics, URGENT COLD INTUBATION In certain circumstances it will NOT be appropriate to proceed with full preparation and induction of anaesthesia. Patients who are in respiratory or cardiac arrest or who have agonal respiration do not need a full equipment set-up or checklist run-through (see below) and should be intubated without drugs. The abreviated “Cold Intubation Checklist” should be used in these cases. If there is residual muscle tone and clear signs of life but the patient is in extremis consideration should be given to intubation using paralysis only. 4 STANDARD PREHOSPITAL EMERGENCY ANAESTHESIA Tracheal intubation following induction/paralysis is the central component of prehospital emergency anaesthesia. It is divided into ten conceptual and practical stages (adapted from Ron Walls – Manual of Emergency Airway Management)4. Preparation! Patient positioning! Pre-oxygenation! Pre-treatment! Paralysis with induction! Protection and positioning! Placement with proof! Plan for failed intubation! Post-intubation management! Packaging and transfer! 1. PREPARATION All patients should have an assessment made as to the likelihood of successful intubation and of successful bag- valve-mask ventilation in the event of failure to intubate. It should be noted that many of the features predictive of a difficult airway, which may be useful in other settings, lack sensitivity and specificity in the prehospital environment and many aspects of a routine pre-anaesthetic assessment are obviously impossible or contra-indicated in our practice5,6. It is beyond the scope of this document to describe all aspects of airway assessment (although in practice difficult airways are most commonly encountered in severe burns, morbid obesity, dysmorphic syndromes and massive facial or airway injuries.) Notwithstanding, a predicted difficult airway should be considered in the decision-making process prior to emergency anaesthesia. In the prehospital phase it may be possible to maintain a patent airway and transport the patient but in MOST patients emergency anaesthesia will need to proceed with full preparation for a surgical airway in the event of inability to intubate and ventilate. Assessment for a difficult airway forms part of the “Emergency Anaesthesia Pre-Intubation Checklist”. Communication is key. The plan for a difficult airway MUST be discussed prior to induction and a specific “Plan B” verbalised during the preparation phase. Equipment Set-Up • The equipment set-up should be standard and automatic for all prehospital emergency anaesthetics. The set- up must be drilled and practiced by the medical team in scenario training. • The standard position for the equipment set-up should be adjacent to the right side of the patient’s head as shown in the picture. The site needs careful consideration to avoid having to move equipment once laid out. Avoid intubating in direct bright sunlight as this can adversely affect visualisation of glottic structures – use shade or an assistant to shield the intubator with a blanket during the procedure. • Monitoring is best positioned on the right side of the patient with the monitor screen easily visible to the doctor and paramedic. The retrieval service Zoll X-Series multimodality monitor should be applied as soon as practicable after arrival on scene to avoid delays in changing over later in the resuscitation. Monitoring should be attached as early as possible (preferably during the doctor’s primary assessment - see 'Prehospital Mission Workflow' Operating Procedure.) 5 • Monitoring will include SpO , NIBP (set cycling interval to 3min), ECG and ETCO 7. Automated NIBP readings are 2 2 preferable to manual ones as they avoid prolonged periods without blood pressure readings and result in earlier detection of hypotension. They also facilitate safe post-intubation sedation particularly in head injured patients. The EMMA capnometer is a backup in case of main monitor ETCO2 failure. ETCO2 monitoring must be used whenever a BVM is applied to a patient whether by face-mask, SGA or tracheal tube. It is the most important monitor of ventilation and airway patency. Loss of ETCO2 trace indicates a loss of airway patency until proven otherwise (equipment failure/circuit disconnection etc). • Oxygen – sufficient oxygen MUST be secured for the pre-oxygenation, extrication and transport phases. A minimum of two full C-size cylinders must be made available. It is essential to prepare this EARLY in the procedure particularly if remote from vehicles. • Suction – the standard prehospital suction device is the Laerdal LCSU-3 compact portable suction unit. Additional sources of suction include a venturi device (from an oxygen cylinder) or vehicle powered suction. Inadequate or failure of suction is a COMMON REASON for intubation failure particularly in facial injuries where bleeding can be torrential and in these cases you can never have too much suction on hand. • Intravenous access - two secure IV (or IO) lines are ideally required for all emergency anaesthetics. Experience has shown that failure or partial failure of induction due to tissued cannulae is much more common in prehospital emergency anaesthesia and is particularly common when IV lines are placed by staff other than the retrieval team. BE AWARE of this problem. A bag of crystalloid on a pump set should be attached and checked to be running well prior to drug administration, but stopped in between. If a second IV line cannot be placed easily an IO should be inserted. • Equipment bags are best placed around the equipment set-up site as a cordon to prevent interference with the procedure. Team positioning needs to be planned and practiced during training. 6 PERSONNEL • Allocate tasks: 2 or 3 person technique depending on setting. o Airway Assistant/ELM assistant o Laryngoscopist o In-line cervical spine immobilisation operator • The delegation of roles and appropriate briefing of staff is an essential task. The doctor is responsible for delegation of staff and their briefing but both members of the team must be aware of this procedure. • The retrieval paramedic is responsible for establishing monitoring and for the equipment set-up. • If there are no features (apart from C-Spine immobilisation) to predict a difficult airway and full pre-oxygenation can be achieved the first attempt at laryngoscopy may be taken by the retrieval paramedic with the doctor becoming the airway assistant and available as second operator if laryngoscopy proves to be difficult. This enables the doctor to maintain the clinical overview of the procedure. All registrars should take a turn at performing laryngoscopy in the prehospital setting during their term and this should be discussed prior to arrival at the scene. • Paramedics must be up to date for the Prehospital Emergency Anaesthesia Currency to perform laryngoscopy. • If a difficult airway is anticipated or adequate pre-oxygenation is difficult then the physician should perform the laryngoscopy. • Non-retrieval service staff should not perform laryngoscopy for emergency anaesthesia regardless of experience unless they have previously practiced or drilled our procedure and remain current for the procedure. • Staff positioning is shown in the picture with in-line cervical immobilisation on the left of the patient keeping the right side clear for the equipment set-up, airway assistant and monitoring. • It is important for ancillary staff to be appropriately briefed on their expected role and actions. The in-line cervical immobilisation operator should be briefed to keep their hands away from the mandible and their arms in line with the long axis of the patient out of the way of the laryngoscopist. CREW RESOURCE MANAGEMENT ISSUES • The key to minimizing scene times is ensuring SIMULTANEOUS ACTIVITY AT ALL TIMES during resuscitation and nowhere is this more important than during emergency anaesthesia. • Always introduce yourselves on arrival and if you can, try to remember the names and designations of staff as you listen to their handover. Most staff are happy to have us there but the service (and the likelihood of our being requested in the future) depends on maintaining good working relationships with on-scene crews. • It is vital that the on-scene paramedics be involved in the resuscitation. This may well be their only serious trauma case for the year and it is essential to involve them as active participants; always being mindful of their skills. • Always consider whether other on-scene staff can be utilised for tasks such as splintage, cannulation, setting up fluids or fetching equipment to free up the clinical team to perform tasks only we can perform (such as the equipment set-up or surgical procedures). • The team need to think several steps ahead and anticipate the need for equipment such as oxygen, suction, a stretcher and the means and route of transport which all of which will be time-consuming if done in a serial fashion. • There should NEVER be on-scene staff standing around quietly watching – there are MANY things to do at once. Even non-medical staff such as fire crew and police can be utilised to create a cordon, remove curious onlookers or act as a drip stand! 7 2. PATIENT POSITIONING • Ensure adequate access to the casualty. Intubation is RARELY necessary in the position in which the injured person is found. The first task after deciding to intubate is to locate the most appropriate place to perform the procedure. • Patients should be extricated to a safe environment (facilitated by analgesia, sedation and regional anaesthetic techniques) e.g. to the roadside on an ambulance stretcher. • Intubation of patients on the ground is much more difficult and only very rarely necessary. • Prehospital anaesthesia should usually only be undertaken when the casualty is in the supine position with relatively easy and full access. The ideal position for intubation is on a stretcher or raised platform with 360 o access. (for example on an ambulance or retrieval stretcher with legs retracted (fully down) at the rear of a vehicle. An alternative is on a stretcher lowered to half-height with the intubator in a kneeling position. If the team plans to depart to hospital by helicopter then ideally emergency anaesthesia will occur next to the EC145 or inside the AW 139 (with the stretcher fully extended). Experience has shown that intubation inside an ambulance vehicle or confined space is more difficult and increases the chances of failure and therefore 360o access to the patient should be obtained where possible. A temporary airway adjunct may be useful whilst repositioning. Positioning the patient just outside the rear of a vehicle has several advantages including access to powered suction, additional lighting and oxygen supplies. A second ambulance stretcher is often available and can be used as an ideal workspace for equipment for an emergency anaesthesia. A second stretcher acts as an excellent work station • Complex extrication movements after anaesthesia are often difficult and the focus for management of trapped patients should be on maintaining oxygenation with rapid extrication if the airway is compromised, under airway adjuncts, supraglottic airway (SGA) such as the i-Gel, or in-situ surgical airway. • Intubation inside an ambulance may occasionally be necessary in severe weather conditions or threatening crowds and this procedure should be practised by all staff. 8 LARYNGOSCOPIST POSITION • Direct laryngoscopy is the process of bringing the glottis into alignment with the eyes of the operator and as such the doctor or paramedic performing laryngoscopy must maximise their position for laryngoscopy. If the patient cannot be moved from the ground then some of the choices include the following. You should try them to see which suits you best: o Kneeling – most versatile rough or soiled ground but often difficult to obtain a good view. o Lying Prone – gets the eye line right but may put the laryngoscopist at a mechanical disadvantage. o Left lateral Position – provides a good eye line and mechanical advantage and comfort may be improved with padding under the left elbow (such as a SAM splint). These techniques may be best practiced in scenario training. Lying Kneeling 9 3. PRE-OXYGENATION • Pre-oxygenation is essential for safe prehospital emergency anaesthesia. It should proceed throughout the preparation phase above. Pre-oxygenation de-nitrogenates and establishes an oxygen reservoir in the lungs, blood and tissues and, if effective, will allow several minutes of apnoea without O desaturation and the need to ventilate 2 the patient. Two nasopharyngeal airways and an oropharyngeal airway with jaw thrust (“Tripod” or “supported Tripod” (with jaw thrust) technique) should be used if there is difficulty maintaining an open airway. • Head injury is NOT an absolute contra-indication to the CAREFUL placement of a nasopharyngeal airway. APNOEIC OXYGENATION • Studies have demonstrated that during apnoea (following muscle relaxant administration in emergency anaesthesia), supplying oxygen to a patent airway can significantly prolong safe apnoea time before desaturation occurs9,10,11,12. This phenomenon is well described in brainstem death testing protocols where oxygenation can be maintained for long periods without ventilation when oxygen is supplied to apnoeic patients via the tracheal tube. • The physiology is relatively straightforward; during apnoea, oxygen is continuously absorbed into the blood from the FRC at a rate of approximately 250mL/min whilst CO continues to accumulate in the blood, only slowly diffusing 2 into the aveoli at a rate of approximately 10mL/min13. This differential creates sub-atmospheric alveolar pressure and a net inflow of gas into the lungs of around 240mL/min in the average anaesthetised human, provided the airway is kept patent. If oxygen (rather than room air) is supplied then the oxygen reservoir in the lungs can be maintained for extended periods. • In our setting this is best accomplished by administration of high flow oxygen at 15L/min by nasal cannulae just prior to induction (when the Emergency Anaesthesia Pre-Intubation Checklist is completed) and left on until successful tracheal intubation is accomplished. The airway is naturally opened during laryngoscopic attempts and this can be augmented by airway adjuncts or jaw thrust. It is also worth noting that the use of nasal cannulae in addition to a non-rebreather reservoir mask (NRB) or self-inflating bag-valve-mask with reservoir (BVM) for pre-oxygenation has been shown to significantly increase FIO in spontaneously breathing patients by washing out ventilatory dead 2 space with oxygen inbetween spontaneous breaths14 and thus increases the effectiveness of pre-oxygenation. Apnoeic oxygenation set-up via nasal canula 10