Asignaciones e incentivos:

When a person phones 999 they have traditionally received an ambulance response and, since 1996, this has invariably been a paramedic response.

The United Kingdom ambulance services use priority dispatch systems to determine which calls are potentially life threatening and hence determine who has a faster response because of life threatening

conditions, but also it allows downgrading of some calls such that lights and sirens may not be needed in some cases, therefore increasing the safety. Research evidence about safety and accuracy of call

prioritisation is limited and there is some conflict in the results. Two British studies (Cooke et al., 1999; Nicholl et al., 1996) have shown marked variances with up to 30% error rate in one study A systematic review of ambulance dispatch and prioritisation systems, by Wilson et

© NCCSDO 2005 41 al. (2002), showed there was poor evidence for their safety and clinical effectiveness. The number of emergency calls received by ambulance services in the UK has risen consistently over recent years. The vast majority of patients are usually taken to emergency departments. In a review of the literature Snooks et al. (1998), have shown that in nine out of ten studies 30% to 52% of ambulance calls did not warrant an emergency ambulance response. It is recognised that the lay person lacks the knowledge and ability to assess the seriousness of the call and that communication difficulties may impede the ability to assess this (Higgins et al., 2001). It has therefore been suggested that it is more appropriate to modify the response from the ambulance service in order to increase the appropriateness of care.

The changes suggested are also likely to reduce attendances at emergency departments and are:

• diversion of non serious 999 calls to a system of nurse advice • ability of ambulance crew to treat people at the scene and then

discharge them

• use of alternative destinations to emergency department. The alternatives for 999 cases that are neither life-threatening nor serious have been summarised by Snooks et al. (2002). They conclude that the evidence supports the need for alternatives to be developed. In 2001, the US National Association of EMS (emergency medical system) Physicians issued a concept paper discussing the new models of care as discussed below.

4.1.2 Divert 999 calls to nurse advice

In the only UK study, a study by Dale et al. (2000; 2003) investigated the potential impact of telephone assessment and triage for callers who present with non-serious problems (category C calls) as classified by ambulance service call-takers in a pragmatic controlled trial. During intervention sessions, nurses or paramedics within the control room used a computerised decision-support system to provide telephone assessment, triage and, if appropriate, advice to permit estimation of the potential impact on ambulance dispatch. Of 635 in the intervention group, 330 (52.0%) were triaged as not requiring an emergency

ambulance, and 119 (36.6%) of these did not attend an emergency department. This compares with 55 (18.1%) of those triaged by a nurse or paramedic as requiring an ambulance (odds ratio 2.62; 95% confidence interval 1.78 to 3.85). Patients triaged as not requiring an emergency ambulance were less likely to be admitted to an inpatient bed (odds ratio 0.55; 95% confidence interval 0.33 to 0.93), but even so 30 (9.2%) were admitted. Nurses were more likely than paramedics to assess calls as requiring an alternative response to emergency ambulance dispatch (odds ratio 1.28; 95% confidence interval 1.12 to 1.47), but the extent to which this relates to aspects of training and

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professional perspective is unclear. The authors did advise that the acceptability, reliability, and cost consequences need to be considered further.

In a prospective cohort study (Schmidt et al., 2003), callers to an urban EMS dispatch system were studied. It was possible to predict a population of callers who could be described as being low risk of having need to attend emergency departments. However negative predicted value only reached 98%. Transfer of non-urgent 911 calls to a nurse adviser have resulted in no adverse patient outcomes while maintaining patient satisfaction (Smith et al., 2001b).

The NHS Service Delivery and Organisation (SDO) Programme has commissioned research to assess the costs and benefits of managing low priority 999 ambulance calls by NHS Direct nurse advisors (see www.sdo.lshtm.ac.uk for more information).

4.1.3 Not taking patients to emergency department

A postal questionnaire study showed that ten of 36 replying UK

ambulance services had investigated non-conveyance of some groups of 999 callers and 13 reported looking at other models of care for category C patients. Only three services had evaluated such work (Snooks et al., 2000). Before such systems can be instituted they need to be assessed for feasibility, safety and effectiveness.

The US Emergency Medical Services Committee has issued guidance (2001) on the non-transport of patients, stating it should only occur in the presence of on-line physician direction or detailed off-line protocols supported by appropriate educational programmes.

One UK study (Cooke, 2001) suggested that as many as 28% of cases were not transported by the ambulance service. An American study suggested that it was 26% of 911 callers (Selden et al., 1991). However, concerns have been expressed about the risk of litigation associated with non-transportation (Goldberg et al., 1990).

Use of standard emergency department triage is not sufficiently accurate for use as a tool to help paramedics determine whether a patient needs to be transported to hospital (Asplin, 2001). A retrospective study of 500 consecutive patients who were not transported following a 999 call in the East Midlands area of the UK showed that 26% of these had been assigned an ‘advanced medical priority dispatch’ (AMPDS) Delta code (the most urgent category) at dispatch prioritisation stage. This study therefore demonstrates that use of prioritisation codes is not a reliable way of determining disposal of the patient. It also illustrated that the high number of falls in the elderly which do not require a 999 response can be dealt with by alternative means (Marks et al., 2002).

A cluster RCT in London involved 409 cases and 425 controls (London Ambulance Service, 2002). The study group were attended to by

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ambulance crews who had had training and extra protocols to enable transport to a minor injuries unit rather than the main emergency department. The study group had no increase in the use of the minor injuries unit and made no more discharges from the scene. Factors found to influence destination were distance from emergency

department and minor injuries unit, time of day, presence of head injury and sex of patient. Those taken to the minor injuries had shorter

ambulance turnaround times. The study therefore did not confirm that the intervention would decrease number of attendances at the

emergency department.

Snooks et al. (2001) undertook a study of ‘treat and refer’ protocols which allowed London ambulance crews to leave appropriate patients at home with referral or self-care advice. Protocols were developed by a local team using published evidence where available and the system was developed with local stakeholders. A total of 719 patients

participated in the study, 260 in the intervention arm and 537 in a control group. The two groups were demographically the same but the study group were more likely to have attended during the day on a weekday. The rate of conveyance to hospital was no different in the two groups and the intervention group had a 5.9 minutes greater job cycle time (p<0.001). This equates to 1001 extra hours of ambulance time per week if applied across the whole of London. The 9% of patients who were left at home, ‘according to protocol’, were

subsequently admitted to hospital within 14 days and were judged by clinical reviewers to have been subject to inappropriate use of the protocols by the paramedics (London Ambulance Service, 2002). Use of protocols by emergency medical technicians to determine patients who did not require treatment and transport was evaluated in the US system (Schmidt et al., 2000). The 3% of patients determined as not requiring an ambulance by on scene assessment by emergency medicine (ambulance) Technicians subsequently had a critical event in the ambulance and 11% had potentially critical events according to ambulance service notes. Another study was conducted in an urban emergency medical service in the United States. Paramedics triaged patients for, study purposes only, into whether they needed to be taken to the emergency department, to see a physician within 24 hours or not need any physician evaluation. The records of all these patients were then subsequently reviewed. Paramedics rated that 85% of patients needed to be taken to an emergency department and 15% were not required to be taken there, of which 12.5% needed to see a physician at some point. On review, the review panel determined that 9.6% of patients were under-triaged, of whom 48.7% were

misclassified because the paramedics misused the guidelines. In addition, 8.4% were incorrectly classified as not needing to come to the emergency department. This represented 55% of the patients categorised as triage category 3 or 4 by the paramedics. The authors therefore conclude that the paramedics using written guidelines do not

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reach an acceptable standard of accuracy to determine disposition of patients in the field (Pointer et al., 2001).

In the Selden study (1991) 22% of non-transported cases were inappropriate and he reviews three other studies in the United States that have also described serious and occasional fatal outcomes. It is also of note that up to 65% of patients leaving the scene needed further help within a week, with up to 20% needing emergency medical care. A trial of treat and release protocol in Albuquerque was

suspended owing to safety concerns (Anon., 1999). When such protocols were introduced in California, it was found that only a very small proportion of eligible patients were taken to alternative sources of care (Plorde et al., 2001).

In an American study to look at whether paramedics could safely determine which patients did not need emergency transportation, paramedics completed a questionnaire for each patient they transported and the notes of these patients were subsequently reviewed to determine whether they needed ambulance transport (defined as needing care in an ambulance on the route to hospital) or emergency department care (defined as needing treatment according to diagnoses that was not available in local urgent care centres). A total of 236 patients were transported and 183 of these had their charts reviewed. The agreement between the paramedics and the need for emergency department attendance was low (k 0.47, 95% CI, 0.34- 0.60), as was agreement between paramedics and the emergency department care (k 0.32, 95% CI = 0.172 - 0.46). Paramedics recommended alternative treatment for 97 patients, 23 of whom needed ambulance transport and the paramedics recommended non- emergency department care for 71 patients, 32 of whom needed emergency care. Therefore, the proportion of patients who could potentially have not been transported who actually needed emergency department care was high (Hauswald, 2002).

A prospective study of consecutive patients transported by a private paramedic service required paramedics to complete a survey detailing the necessity of transport to emergency departments for each patient. The paramedics had been informed that the patients should be

designated requiring emergency department care if they were to be admitted, required surgical subspecialty obstetrical or gynaecological consultation, or required advanced radiological procedures excluding plain x-rays. A total of 313 patients were enrolled. Paramedic

assessment was 81% sensitive (95% confidence interval 72% to 80%) and 34% specific (95% confidence interval 28% to 41%,). In predicting requirement for emergency department care, in 85 cases paramedics felt transport to the emergency department was unnecessary, while 27 (32%) met the criteria for emergency department treatment, including 18% who were admitted and five who were admitted to the intensive care unit (Silvestri et al., 2002).

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An American study (Kamper et al., 2001) evaluated the feasibility of paramedics treating minor illness and injury conditions in the field. Data from 1103 ambulance report forms was analysed to determine whether there were any high volume groups of minor conditions. Of the 115 commonest conditions suitable for paramedic in-field treatment all contained 24% to 100% of complex conditions believed to be beyond the remit of pre-hospital care, requiring facilities of a hospital. It did not address whether the paramedics could identify these cases, so they could safely treat the others.

Most UK ambulance services have protocols indicating transport of patients following treatment of hypoglycaemia. A Copenhagen study (Andersson et al., 2002) shows that these patients can be safely treated and 84% left at home if they satisfy certain criteria, although 8% needed subsequent care within 72 hours, with 5% experiencing a second hypoglycaemia and one needing hospital admission, but none suffered long-term adverse outcome.

The NHS Modernisation Agency is currently looking at developing emergency care practitioners, one of whose roles is to undertake treatment and then discharge patients from the scene. This is discussed further in section 4.9.4.

A study of community paramedics for older people with minor injuries has been commenced in Sheffield and is presently being evaluated (Mason et al., 2003).