Standards of care Although the aim should always be to maintain high stand- ards of care, t he need for pragmatism must be recognized. As the number of patients requiring mechanical v entilatory support rises and staf \201 ng ratios become more dif \201 cult, it is inevita ble that the risks of adverse events will increase. When resources are signi \201 cantly o verstretched, inter- ventions normally considered appropriate may not be achievable because of availability of staff, equipment or consumables. Staff who undertake responsibility for care of patients or procedures that are outside of their normal working practice need to h ave strong reassurance that they will not be vulnerable to professional criticism or litiga tion for doing the best that they can under dif \201 cult circumstances. Until this concep t is formally supported nationally, the responsibility for providing adequate reassurance a nd support for staff must lie with local trust management and SHAs. Pediatrics Dealing with a signi \201 cant number of infants and children who require criti cal care support will pose a major challenge. Pediatric ICUs already run at high levels of capacity and, even if escalation plans are enacted, will have limited ability to cope with increased demand. A local major incident could also produce the requirement for a number of children to receive critical care stabilization procedures prior to transfer to other cent ers. This reinforces the importance of preserving pediatric stabilization expertise in all hospitals where children may be admitted. Further reading Christian MD, Hawryluck, L, Wax RS, et al. Development of a triage protocol for critical care during an in \202 uenza pandemic. CMAJ 2006; 175: 1377 \200\22381. http://www.aic.cuhk.edu.hk/web8/BASIC.htm http://www.dh.gov.uk/en/Publicationsandstatist ic s/Publications/PublicationsPolicyAndGuidanc e/DH_073179 Supplies and disposables Pandemic in \202 uenza planning has led to recognition that most NHS institutions depend on a \200\230just in time \200\231 supply system, and that mechani sms have to be re \201 ned to ensure that supply chains can be maintained during a major i nci- dent. Although a considerable amount of work has been put into this, it remains far fr om certain that supply systems will be suf \201 ciently robust to maintain essential servi ces, particularly as demand for some items may signi \201 cantly exceed normal requirement s. Cooperative networking arrangements will help units to cope with a local or even a regio nal major incident, but an event which results in simul- taneous increased demand for suppl ies will pose a major challenge. Menon DK, Taylor BL, Ridley SA. The Intensive Care Society, UK. Modeling the impact of an i n \202 uenza pandemic on critical care services in England. Anesthesia 2005; 60: 952 \200 \2234. Qureshi K, Gershon RRM, Sherman MF et al. Health care workers \200\231 ability and willingn ess to report to duty during catastrophic d isasters. Bull NY Acad Med 2005; 82: 378 \200 \22388. Suntharalingam G, Perry MR, Ward S, et al. Cytokine storm in a Phase 1 trial of the anti-CD 28 monoclonal antibody TGN1412. N Engl J Med 2006; 355: 1018 \200\22328. UK Department of Health. UK Health Department \200\231s in \202 uenza pandemic contingency plan. London: DoH, 2005. www.dh.gov.uk/prod_consum_dh/groups/dh_digita- lasets/@dh/@en/documents/digitalasset/ dh_41 37619.pdf (2006) Critical Care Contingency Planning. Triaging and ethics These are the most complex problems that critical care staff may face, and many issues remain unresolved. In smaller incidents where local/regional expansion and 574 M JONAS & CS WALDMANN Health technology assessment De \201 nition \200\230Health technologies \200\231 are broadly de \201 ned to include a ll interventions used to promote health, prevent and treat disease, and improve rehabilitat ion and long-term care. This may include drugs, devices, procedures (surgical tech- niques, screening and counseling) and even the settings of care, such as general practice, hospita ls and care homes. process will be of bene \201 t or be safe in clinical use. In the USA, the FDA ful \201 l s a similar role but, in addition, before granting approval for sale in the USA, has a remi t beyond the technical quali \201 cations of the CE mark and mandates some assessment of c linical operation. The FDA uses clini- cal experts to review investigational studies relati ng to the device to ascertain whether the product does what is claimed by the manufacturer and/or presents unreasonable risks to the patient. The FDA classify devices into three clas ses according to the risk of potential harm to the user, ranging from Class 1 devices that present minimal risk to the user, e.g. home blood pressure kits, to Class 3, e.g. dialysis machines or ICU ventilators Background The NHS Technology Assessment Program was set up in 1993, and the \201 ndings and output from this Program directly in \202 uence key decision-making bodies such as the NICE. Although the de \201 nition of health technology assess- ment (HTA) presents a wide spectrum of interventions, with the exception of drug based technologies, most of the prin ciples involved can be considered with reference to medical devices. The drug-based technol ogies and pharmaceutical industry are tightly legislated and require assessments ranging fr om animal studies to large interventional clinical trials. In contrast, medical devices hav e relatively little legislature surrounding clinical introduction, and there frequently may not be a consensus as to what constitutes adequate assessment. There is as a result a need for further develop- ments of the science relating to HTA. This is especially pertinent wh en consideration of the escalating numbers of devices for which manufacturers make claims r elating to patient care. The ensuing HTA exercises stipulate study design and assessment of these new technologies in an attempt to judge and evaluate short- and long-term bene \201 ts. In effect, there are two questions to answer: does the device have a positive clinical impact and are the resultant economics affordable in the context of local/national healthc are funding? The requirement for a balanced approach of science vs economics ensures that t he assessment design will draw on expertise from clinicians, engineers, statisticians, econ omists, ethicists and of course lawyers. Device performance Ef \201 cacy and effectiveness are used to assess device per- formance. The ef \201 cacy relates to the device performance under ideal conditions, and the effect iveness is the per- formance under normal clinical working conditions. This is an important distinction as ef \201 cacy ratings may indicate the necessity for \200\230experts \200 \231 to operate the device, whereas effectiveness relates to the performance limitations un der average clinical conditions. Overall, when reviewing tech- nology, the new approach sho uld offer improvement over current technologies. This may be because the device can obtain measurements with less risk to the patient, i.e. is less invasive, or has some other aspect which is advanta- geous. Ef \201 cacy Assessing ef \201 cacy usually means comparison of the device against a know n \200\230gold \200\231 standard. When the measurement is well de \201 ned, e.g. cardiac output, the ef \201 cacy becomes the mathematical correlate of accuracy. Accuracy is the c loseness of the device measurement to the actual value and can be described by: \200 \200 \200 Correlation (degree of association between readings) Precision (the closeness of repeated m easurements) Bias (the difference between the means of the measurements) The repeatability and inaccuracy of the gold standard is important as if it has a varying a ccuracy then the limits of agreement between it and the technology under scrutiny become wi der and less meaningful, and this makes de \201 ni- tive comparisons difficult, e.g. therm odilution cardiac output vs other technologies Where a gold standard reference does not exi st, then it is necessary to show that the technology has a clinical utility, usually in rel ation to patient outcomes. This suggests that the monitor has to be able to detect a variab le which when targeted will affect outcome. The ef \201 cacy assessment here, where there is not a gold standard, is the determination of the sensitivity, speci \201 city and predi ctive values: The assessment process The HTA process has three core areas: \200 \200 \200 device safety, device performance device cost. Device safety This is a complex area where there may be safety aspects related to using a d evice as well as the clinical process and context in which the device is used. Safety also encom- passes accuracy of the device, as inappropriate clinical decisions can result from i naccurate measurements. Frequently overlooked is the obverse component of the assessment pr ocess which should scrutinize the impact of not using the device. Assessing the safety of t he device or box itself is a statu- tory requirement and includes elements of electrical sa fety, detailed multi-lingual instructions, packaging, conformation to environmental speci \201 cations and disposal instructions. All of these issues are dealed with using a Europea n Standard, referred to as the CE mark (La Conformitee Europeenne), which certi \201 es th at technical manufacturing standards have been met. It is not a functional guarantee that t he device or Outcome improved Outcome not improved Positive Negative A C B D Sensitivity = A/A+C Positive predictive value = A/A + B Speci \201 city = D/B + D Negative predictive value = D/C + D 575 CHAPTER 33.13 Health technology assessment Effectiveness Assessment of effectiveness requires clinical trials in which the technology is used as it would be under average conditions. Standard rules of engagement for conduct o f comparative studies are important to produce valid results, and it must be appreciated th at there may be issues related to study design. The two obvious trials are a technology vs a control, or the technology with its measurement guiding subsequent ther- apeutic manageme nt. For the former type of trial, the data are usually comparative, whereas for the latter the results tend to be clinical outcome based. For outcome data, the ideal measurement is c onsidered to be mortality but, because of the resource implications of numbers needed to po wer studies for mortality, the use of surrogates such as length of hospital stay or number of complications is common. If using a device to guide therapy, it is important to consider the relative contributions of the device being assessed as opposed to the therapeutic inte rventions of the protocol which may be the important determinant of the results. is wide enough to encourage innovation and a statement of business need to which the market can make a meaning- ful response; it must also specify achievable timeframes within the EU Procurement rules. The rules prescribe how the tenders are advertised and awarded. Current ly contracts over the following values are subject to these rules: Type of contract OJEU threshold Supplies Contracts Service Contracts \200\224Part A Service Contracts \200\224Part B Works Contracts 93 738 93 738 144 371 3 611 319 The tender is advertised in the Supplement to the Of \201 cial Journal of the European Uni on (OJEU) and under the EU regulations there are three types of tender procedure available to buyers: The open procedure This is available in all circumstances and involves a single- stage appr oach, where all candidates may respond to the OJEU advertisement and all offers received mu st be considered. Device cost The economics related to health technologies is a key driver for HTA. These pri nciples provide a safeguard for a \201 nite and shrinking health budget and represent an attempt to ensure that resources and bene \201 ts are spread and do not favor one particul ar group. The area of cost con- tainment is complex, as in many situations the only costs c onsidered are \200\230direct \200\231 costs relating to the technology and disposables. Fr equently the indirect costs such as training and storage are ignored, and these may represe nt a consid- erable \201 nancial load, e.g. a Clinical Information System may have a mone tary cost per bed, but staff training, education and maintenance personnel may generate con siderable additional add-on costs. The restricted procedure This is available in all circumstances and involves a two- stage a pproach where candidates who respond to the OJEU advertisement will be considered to have e xpressed an interest. The buyer will shortlist a number of these, who will then be invited to submit offers. Where the restricted procedure is used, the buyer must allow a minimum of 37 days from the date the OJEU notice was despatched to the closing date for receipt of ex pres- sions of interest. Once shortlisting has taken place, a minimum of 40 days must be al lowed for offers to be returned Practical use of HTA principles In the hospital arena, the principles of HTA are used to en able decisions for device procurement. When purchas- ing a device, the functionality, i.e. safety and performance, has to be considered in relation to the cost. The selection criteri a for the purchase and replacement of medical devices depends on cost and numbers being pur chased. The selection process should also include an evaluation of the manufacturer/supplie r in terms of track record, pro \201 le in the local and national healthcare market, compa ny \201 nan- cial stability/survival, and service capability and response times. The even tual procurement of technologies usually follows a de \201 ned process dependent on the si ze and cost of the intended purchase. High value public sector tenders are covered by speci al European Competition rules (OJEU). These rules are designed to guarantee open and fair c ompetition across all EU states. The negotiated procedure This is only available in a very limited number of circum- stances and is subject to strict conditions. The most common tender used is the restricted proce- dure, as the open procedure is expensive and time consuming, and there is limited applicabi lity surrounding the negotiated procedure. Further reading Critchley LAH, Critchley JAJH A meta-analysis of studies using bias and pre cision statistics to compare cardiac output measurement technologies J Clin Monit 1999; 15: 85 \200\22391. Guyatt GH, Tugwell PX, Feeny DH, et al. A framework for clinical evaluation of diagnostic t echnologies CMAJ 1986;134: 587 \200\22394. OJEU www.ted.europa.eu Procurement Policies and standards http://www.ogc.gov. uk/procurement Sibbald WJ,Inman KJ. Problems in assessing the technology of critical care medicine. Int J Technol Assess Health Care 1992; 8: 419 \200\22343. The tender process \200\224the OJEU limits The OJEU notice re \202 ects business needs and priorities, and should achieve a realistic balance between a scope that 576 A BATCHELOR Transfer of the critically ill patient \200 Urinary catheter and NG tube on free drainage. Ensure normothermia prior to transportl it \200\231s very easy to get cold in an ambulance. Primary transfer is from the scene of an incident. Secondary transfer is between medical fa cilities or within the same facility for surgery or investigation. This chapter deals only with secondary transfer. Transfer either intra- or interhospital requires the same preparat ions. Patient trans- fers can and should be safe. Some patients should be transported without stabilization, e.g. those requiring urgent de \201 nitive surgical treatment for whom attempts at stabilization will compromise survival, such as leaking abdominal aortic aneurysm. Components of a transfer Patient Reason to move There must be a good reason to move, e.g. u pgrade care, surgery, investigation, repatriation or because of lack of ICU beds. The reaso n should be documented. Moving one patient to make way for another when that move is not in the patient \200\231s best interests requires careful consideration at consultant level an d consent from both patient and family. Surgical including burns Leaking oesophageal varices \200\224take appropriate advice on pla cement of a Sengstaken \200\223Blackmore tube if patient must be transferred to another sit e for hemorrhage control. Burns \200\224if in doubt protect the airway; swelling can be sev ere and delayed intubation may be dif \201 cult. Use a high concentration of oxygen if car bon monoxide or inhalation injury is suspected until levels are established. For respira- t ory or limb circulatory problems, perform escharotomies prior to transfer; diagrams can be faxed from a burn center to guide these. Fluid requirements can be large, and formu- lae es pecially in the presence of inhalation injury are only a guide; aim for urine output >0.5ml /kg/h. Maintain body temperature or re-warm; cold water immersion/irrigation and exposure c an result in hypothermia. Cover burn with clean dry dressings or cling \201 lm. Physiology of transportation Acceleration and deceleration in an ambulance can cause profou nd shifts of \202 uid in the circulation, particularly in patients who are vasodilated, h ypovolaemic or dysauto- nomic, with adverse effect on cardiac output and blood pressure. Th is affects both systemic and pulmonary circula- tions, worsening ventilation \200\223perfus ion matching and neces- sitating increased minute ventilation and inspired oxygen to mainta in the same ABGs. Ideally patients would be placed across the direction of travel; however, this is rarely possible as the position of the trolley is determined by the ambulance layo ut. Neurosurgical Avoid secondary injury; maintain oxygenation and blood pressure. Treat other causes of hemorrhage, e.g. splenic rupture, prior to transfer to avoid hypotension. If pati ent is otherwise stable, aim for a prompt departure; early evacuation of blood clots leads to optimal outcome. Pre-transfer stabilization The patient must be stable and well resuscitated. \200 Equipment Ensure competence with all devices before transfer. All equipment used in an ambu lance must be securely attached to the transportation trolley and able to withstand a 10g f orce. The patient should be secured to the trolley with a 5-point restraint. Endotracheal intubation is indicated if blood gasses are poor, GCS <9, or a higher but decl ining score, or if there is airway compromise, e.g. burns or facial trauma. Intubation in a moving vehicle or in a lay-by at the side of the road may not be easy and should be avoide d. The tube should be well secured. The patient should be attached and stabilized on the tr ansportation ventilator for a period prior to departure to allow blood gasses to be checked and adequacy of venti- lation established. Consider paralysis to facilitate ventila- tion and prevent unplanned self-extubation. Hand ventilation is unacceptable. Volume: full patie nts travel better than empty ones. Resuscitate using sequential \202 uid challenges accom pa- nied by appropriate use of vasoconstrictors. Insert at least two large bore peripheral lines; central venous access may also be required for infusions. All lines should be well s ecured. Identify and drain pneumothoraces prior to transfer If patient has received thrombo lysis for MI, remember reperfusion arrhythmias and consider delaying transfer. Electrolytes , if potassium <3 or >6.5mmol/l correct before transfer. Correct magnesium if low in the pr es- ence of rhythm disturbance. Fractures: splint to avoid pain and further injury. Pelvic fractures have signi \201 cant blood loss \200\224consider external \201 xation if possi ble. Monitoring It is important to know your equipment and how and where it is stored. Monitors should be robust, intuitive and have an easily viewed screen, battery powered and kept char ged. Need to know type of battery and whether it is susceptible to memory problems and poor charging. Batteries must be interchangeable in use without loss of monitoring. \200 \200 5-lead ECG Preferably invasive blood pressure; non-invasive is more susceptible to movement interference and is expensive on battery power. Pulse oximetry Exhaled carbon dioxide If a pulmonary artery cather is used, the pressure must be continually monitored to avoid spont aneous wedging or it must be withdrawn into the SVC for transfer. Core temperature Airway p ressure \200 \200 \200 \200 577 CHAPTER 33.14 Transfer of the critically ill patient Ventilator Ventilators must be robust, have a wide range of settings for tidal volume, I:E ratio, rate and PEEP to accommodate most patients. Preferably battery powered and economica l with oxygen \200\224any gas used for the ventilator must be known and taken into account along with respiratory gas. It should have a disconnect alarm. Communication The referring hospital must ensure the recipient hospital is able to provide the care and treatment the patient requires before agreeing to transfer the patient. The re cipient hospital must have spare capacity before accepting the patient. Whilst negotiating the transfer, the most senior clinician involved should provide a full and detailed verbal case summary including MRSA and C. dif \201 cile status. The clinician caring for the pati ent must give a detailed hand- over to the transferring team including all investigations a nd results. The transfer team should then give a full handover to the recipient team. The t eam must have a means of communicating with their base whilst en route; mobile phones may b e used. The receiving hospital should be given an estimated time of arrival and informed wh en the patient is en route. It is not appropriate for relatives to travel in an ambulance w ith the patient unless the patient is a child. Oxygen Calculate the amount of oxygen required for the projected transfer duration and incl ude any driving gas for the venti- lator. Take double this amount and at least an hour \200 \231s supply in case of unexpected delays. If using the ambulance supply, check these cylin ders contain enough for your projected journey time. Check connections are compatible. Take an ambu bag with reservoir and face mask in case of ventilator failure or unplanned extuba tion. Volume of oxygen in standard UK cylinders in litres. D size E size F size 340 680 1360 Documentation The reason for transfer along with conversations with other teams, patient an d family should all be documented. Physiological observations should be charted during tran s- fer. Many networks have multicopy transfer forms so that copies can be kept by the refer ring team and the network for audit, as well as a copy placed in the patient notes. Take al l notes and X-rays on CD. Any critical incidents should be fully documented Infusion All \202 uids must be administered via electronically controlled devices, avoid hanging bags of \202 uid; movement and transfer may result in air in the infusion tubing. Drugs Stop all unnecessary infusions before transportation. Essential infusions should be m ade in a concentration such that syringe changes will not be required en route. If infusion concentrations are changed, allow a period of stabilization on the new concentrations prio r to departure. Take spare pre-prepared syringes in case of problems. All syringes should b e clearly labeled. Emergency drugs should prefer- ably be in pre-loaded syringes. Mode of transportation Aeromedical transportation is covered in Chapter 33.15. Ambulances a re not standard and vary considerably, so check you are happy with all the equipment before loading the patient. Many ambulances only have room for 2 rear passengers, in addition to the patient; negotiate in advance who will travel with the patient. Patient and team safety It is important to consider the safety not only of the patient but also that of the team. All members should wear seat belts. Protective re \202 ective cloth ing should be available. Each team member should be aware of his insurance status. Hospital Trusts may not arrange appropriate cover, and professional bodies may take out cover for t heir members. Transfer team Ideally all patients would be transferred by a specialized transfer team; in most cases this is not feasible for many reasons including cost, availability and the requi rement for rapid treatment in, for example, head injury. All anesthesia and critical care s taff should undergo transfer training in the necessary skills and be competent in the use o f all the equipment. It is not essential that all transfers are under- taken by doctors, bu t it is essential that the accompanying personnel are competent and have indemnity. Whilst it is not acceptable to send the most junior inexpe- rienced member of the hospital team on a transfer because they will be least missed, it is important to consider both the patient being transferred and those left behind, and distribute skills accordingly. The team membe rs have the ultimate veto on the transfer if they are unhappy that the patient, the equipme nt or they are not \201 t for the transfer. The transfer team members should be involved in patient stabilization and the decision about \201 tness for and timing of transfer. It is inappropriate for someone who does not know the patient and their problems to be involv ed in a transfer. Team members must be adequately insured and have suitable protective kit; they must have prior arranged transportation back to base. Ethics of transfer Transfer a patient because they will bene \201 t from it, e.g. transfer to burns center. Protect and stabilize the patient so they do not come to harm. If possibl e, discuss move with patient and seek their view. In exceptional circumstances, a patient m ay be moved to free up resources for another patient, i.e. for the bene \201 t of another. Medicolegal aspects Prior to transportation it may be appropriate to take advice from the r eceiving center on patient treatment; however, it remains the responsibility of the referri ng clinicians to decide if it is the correct advice. Handover of responsibility follows for mal handover; the transfer team accepts responsibility from the referring unit and then han ds over to the receiving unit. Hospitals should 578 A BATCHELOR Further reading Guidelines for the transportation of the critically ill adult. Intensive Ca re Society 2002 http://www.ics.ac.uk/icmprof/ standards.asp?menuid=7 agree lines of legal responsibility if a transfer team is used and they wish to stabilize a patient at the referring hospital where they are not employed. Checklist system Each unit or preferably network should establish a check- list which inclu des all of the above points; this should be with the patient documentation and should be fo rmally worked through prior to every transfer and signed by the team members. Recommendations for the safe transfer of patients with brain injury. Association of Anesthetists 2006 http://www.aagbi.org/publications/guidelines. htm#t This page intentionally left blank 580 S HUGHES Aeromedical evacuation Cabin heating may be poorly controlled or slow to respond to changes in temperature. Staff must be vigilant in moni- toring the patient \200\231s temperature and avoiding hypothermia , and ensure they also wear suitable \202 ight clothing. Aeromedical evacuation is used to transfer critically ill patients over large distances or where road transfer would be impractical due to terrain, road condition, traf \201 c etc. It comprises \201 xed wing aircraft or rotary wing (helicopters). Aeromedical transfer ma y be required to upgrade the level of critical care facility or to repatriate a patient fro m overseas. The principles of patient transfer by air are identical to those for road inter -hospital transfer with the same level of monitoring and treatment and attention to patient and medical team safety. The peculiarities of the aeromedical environment need additional consideration. Atmospheric pressure Oxygen Dalton \200\231s Law dictates that the partial pressure of oxyg en decreases with altitude. Except for operations in high mountainous regions, this is not usually a problem for helicopters (typical cruise altitude 2000ft). Fixed wing jet aircraft \202 y at greater altitudes for reasons of aerodynamic ef \201 ciency and thus require cabin pressurization. According to the age and ef \201 ciency of the airframe and pressuri zation system, a set \200\230cabin altitude \200\231 can be achieved. Commercial aircraft \202 y at altitudes up to 40 000ft and typically achieve cabin altitudes of 7000ft. Atmos pheric pressure at this altitude is 586mm Hg compared with 760 mm Hg at sea level. Correspo nding PaO2s are 73 and 103 mm Hg. Critically ill patients with high alveolar arterial gradi ents may become hypoxic at such cabin altitudes despite FiO2 of 1.0. Prior consideration mu st be given to anticipated increased oxygen requirements at altitude. If necessary, the air crew can be requested to provide sea level cabin pressurization. Typically this necessitate s \202 ying at altitudes of 20 000ft, which increases fuel consumption. Aside from cost i mplica- tions, this may necessitate more frequent refueling stops, which will signi \201 c antly increase journey time with roll-on implications for patient safety, battery requireme nts, total oxygen requirements, fatigue, etc. Adverse meteoro- logical conditions may on oc casion prevent \202 ying at lower altitude. Choice of aircraft Speed and distance Helicopters typically cruise at 120 \200\223150 knots (220 \200\223280km/h) with a useful radius of 50 \200\223300km. Time taken to prepare and launch the helicopter and also fuel endurance limit their advantages for very short or long distances, but the advantage over \201 xed wing aircraft is the ability to operate from a range of surfaces, e.g. dedicated helipads, parking areas, recreational parks and \201 elds. Fixed wing aircraft bene \201 t from increased cruise speed (from 300km/h for piston engine aircraft to 850km/h for jet aircraft) and are best suited for ranges of 200 \200 \2232000km. They require pre- pared runways necessitating road or helicopter ambulance tran sfer between hospital and airport at each end. Environmental factors Helicopter The internal noise levels are frequently >95dB(A) such tha t normal conversation is impossible. Auscultation is redundant, as is reliance on audible m onitor alarms. Intercom headsets are required for crew communication. Earplugs are used for all patients regardless of conscious state to reduce hearing damage. Cabin lighting may be poor due to the dangers of distracting the aircrew and adversely affecting pilot night vis ion. Blue or red lighting may be used instead of white light, which may make moni- tors, cy anosis, veins and patient movement dif \201 cult to see. Vibration is greatest at take-off and landing and may induce pain in unstable fractures, and makes accurate adjustment of \202 uid infusion rates dif \201 cult. Pressure According to Boyle \200\231s Law, as the atmospheric pressure falls, gas volume in creases. At a cabin altitude of 7000ft this represents an increase of 27% as opposed to 8% at a typical helicopter altitude of 2000ft. Travelers will be familiar with expansion of ai r in nasal sinuses, the middle ear and the GI tract, but careful consideration must be give n in disease states. Pneumothoraces, pneumocephalus, bubble emboli and trapped air in the a bdominal cavity post- laparotomy will all expand proportional to the drop in cabin pressure . Consideration should also be given to splitting orthopedic casts. Chest drains should be inserted where necessary prior to departure and left in situ for the duration of the \202 ight. All surgical drains should be unclamped and patent. ETT cuffs should either be \201 lled with saline or have their pressure rigorously checked and adjusted in- \202 ight . Ensure pulmonary artery catheter balloons are fully de \202 ated. Fixed wing \202 ights Continuous noise, vibration, changes in temperature, cramped space, ultraviolet radiation and time zone changes contribute to high levels of fatigue. Limited chance for rotation of medical personnel en route may mean extended working hours; therefor e, appropriate rest periods prior to and after \202 ights should be scheduled in staff ro sters. Staff should ensure they are physically \201 t to \202 y, not suffer- ing from t he effects of respiratory infections and be under the residual effects of neither medicatio n nor alcohol. Neither helicopters nor small \201 xed wing aircraft have toilet facilitie s. Axial tilt, acceleration and deceleration forces may be signi \201 cant during take-off , landing and extreme turbulence in \201 xed wing aircraft. Adverse effects on haemodynam ics and ICP may result. Altering patient orientation within the cabin during the \202 igh t to attenuate these forces is impractical. Equipment: key points Whilst the standard of monitoring needs to be equivalent to that in a n ICU, aeromedical equipment needs to ful \201 l additional criteria: \200 Portability and size. Each aircraft has a maximum permit- ted payload, and smaller helicopt ers are particularly limited in this regard. Trade-offs may have to be made with total fuel carried to allow additional weight, but this adversely affects \202 ight endurance. Airc raft performance is signi \201 cantly affected by ambient temperature and 581 CHAPTER 33.15 Aeromedical evacuation are essential. ABGs must be examined after the patient has been stabilized on the transport ation ventilator. For anything other than short transfers, monitoring ABGs en route is reco mmended. The importance of rigorously securing the airway cannot be overemphasized. All IV access, infusion lines, monitoring equipment, drains, etc. must be checked, rechecked and s ecured. Spare IV access is essential. Arrange infusion lines and monitoring equipment such that they are free from tangling and lie in such a fashion that they will be accessible acc ording to the particular aircraft used. Access to the patient \200\231s limbs, chest and ab domen may be restricted in \202 ight, depending on the layout of the aircraft. Always pla n for the worst case scenario, and consider how emer- gency re-intubation or CPR would be p erformed in the cabin. Prior to moving the patient, all loose equipment around the patient should be safely secured to guard against downdraft from helicopter blades or wind when mov ing the patient around exposed airport areas. The patient must be secured onto the stretche r with a harness approved for aviation use. Before leaving the referring hospital, a \201 nal check of the patient, equipment and team is performed and contact made with the aircre w to ensure the aircraft is fully fueled, ready to receive the patient and there are no pro blems with the planned routing. air \201 eld altitude. Less payload can be carried when taking off from hot, high air \201 elds. Suf \201 ciently rugged to withstand knocks and falls. Reliable and extended ba ttery life, with lightweight batteries preferably changeable without interrupting monitorin g. Do not rely on being able to connect equip- ment to aircraft electrical supply. Clear ba cklit displays that can be easily read even in direct sunlight and with vibration. Ability to withstand acceleration/deceleration forces, vibration, extreme temperature changes, and not inter- fere with aircraft avionics or electrical systems (e.g. de \201 - brillators). Ventilators should be oxygen ef \201 cient and deliver con- sistent tidal volumes irrespec tive of ambient pressure. Any integral on-board oxygen systems must be rigor- ously checked and maintained. Portable cylinders should be available in the event of systems failure, an d for patient transfer at each end of the \202 ight. Dedicated oxygen cylinders need to b e carried on commercial aircraft as the integral passenger supply is for use in emergency d ecompression only. Oxygen is dangerous air cargo and needs of \201 cial clearance for its carriage. Always plan suf \201 cient oxygen in case of patient respira- tory deterioration , aircraft delay or diversion. It is imperative that medical staff familiarize themselves w ith whichever oxygen system is used, and rigorously monitor consumption rate and contents. In-line oxygen analysers are recommended. Ideally the equipment can be neatly stacked to ma ximize access and minimize space occupied. Several organi- zations use specially designed e quipment bridges to facilitate this. Drugs and consumable equipment need to be easily vis- ualized and rapidly accessible. Thomas packs are popular as they are easily carried with ru cksack straps, and have compartmentalized sections with clear pockets. Equipment should be arranged according to indication for use, e.g. airway equipment. There must be a system for regular checks to ensure all equipment is present and serviceable, and a system to restock equipment rapidly after use. Drugs must be within expiry dates and kept at the required te mperature. Controlled drugs need writ- ten authority for carriage across borders. Transform ers and adaptors will be required to ensure charging capability overseas. \200 Safety The aircraft is an unfamiliar environment for most medical staff. Safety of the pati ent and aeromedical team is para- mount. Staff must undergo training in aeromedical evacua- tion and an orientation to the equipment and aircraft, with emphasis placed on common airc raft emergencies, emer- gency evacuation procedures, emergency depressurization, communicat ion procedures and survival equipment. The tail rotor and main rotors of helicopters can be lethal, and even provide hazardous obstacles when motionless. Underwater escape training f rom a helicopter simulator is recommended where \202 ights may take place over water. Wit hout proper training, disorientation and confusion are likely, and the ability for staff to provide the best patient care will be adversely affected. A study examining the ability of medical staff to provide CPR to mannequins dur- ing helicopter \202 ight showed signi \201 cant differences between those who had undergone training in aeromedical evacua- tion and those who had not. No pressure must be put on the aircrew to alter their normal safety procedures. The captain has the \201 nal say on whether the conditions are suitable for \202 ight, no matter what the condition of the patient. Clinical governance mechanisms sho uld be in place for reporting and investigation of critical incidents. Preparing the patient for transportation As far as possible the patient must be stabilized prior to transfer. Any necessary interventions and treatments need to be done prior to leav ing the referring hospital e.g. chest drains, -rays, invasive pressure monitoring. A formal handover of the patient by medical and nursing staff is essential, as are written notes, r esults of investiga- tions and copies of imaging procedures. The referring medical staff sh ould communicate directly with the receiv- ing institution medical staff. The transfer team should speak directly with the receiving staff if further advice is required, and con \201 rm an approximate arrival time. Recent blood results including biochemistry, glucose a nd hemoglobin Further reading Everest E, Munford B. Transportation of the critically ill. In: Bersten AD, Soni N, eds. Oh \200\231s intensive care manual, Philadelphia, PA: Butterworth-Heinemann, 2003: 21 \200\22332.