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Unsuccessful conscious sedation on patients with a learning disability and / or autism: a multi-site service evaluation

J. Li*¹
J. Joseph²
X. Yeo³
H. Hossenally^{4
1, 2}Dental Core Trainee in Special Care Dentistry at The Royal London Dental Hospital, Barts Health NHS Trust
³Specialty Registrar in Special Care Dentistry at The Royal London Dental Hospital, Barts Health NHS Trust
⁴Consultant in Special Care Dentistry at The Royal London Dental Hospital, Barts Health NHS Trust; Specialist in Special Care Dentistry, Sedation Lead at Whittington Health NHS Trust
* Correspondence to: Dr Jennifer Li
Email: Jennifer.li4@nhs.net
Li J, Joseph J, Yeo X. Unsuccessful conscious sedation on patients with a learning disability and/or autism: a multi-site service evaluation. SAAD Dig. 2024: 40(1): 37-41

Abstract 

Introduction
Dentist-led conscious sedation improves access to dental care for patients with a learning disability (LD) and autism spectrum disorder (ASD). This service evaluation investigated cases of unsuccessful sedation to study the demographic and trend.

Aims

• To evaluate the reasons for failure of intranasal, oral, and intravenous (IV) conscious sedation
• To assess if there is a correlation between patient factors and sedation failure
• To identify if there are ways to improve the success of conscious sedation for patients with LD and ASD.

Methodology
A retrospective review of clinical notes of unsuccessful sedation cases was conducted from January 2019 to July 2021 across two dental services in London. Unsuccessful sedation was defined as ‘planned treatment unable to be carried out in its entirety, not including treatment modifications’.

Results
A total of 452 patients with LD / ASD were included. Unsuccessful sedation was reported in 34 cases (7.5%). All patients lacked capacity and 62% were non-verbal. Reasons for failure included: failure to cannulate (44%); movement (38%); challenging behaviour (9%); inability to maintain satisfactory oxygen saturation (3%); and short sedation window (6%). The mean dose of IV midazolam administered was 8 mg (range 2 - 18 mg).

Conclusion
Multiple patient factors play a role in unsuccessful sedation. Improved and standardised documentation of sedation and operating conditions are needed to facilitate further evaluation.

Introduction 

The provision of dental care for patients with Learning Disabilities (LD) and / or Autism Spectrum Disorder (ASD) poses challenges to the dental team. There should be ‘reasonable adjustment’ for special care patients to access equitable dental treatment. 

Conscious sedation is a less invasive alternative to general anaesthetic (GA), to enable the diagnosis and treatment of patients with LD and / or ASD. Multiple sedation techniques may be utilised including a combination of intravenous (IV), oral or intranasal (IN) routes. Although the efficacy of conscious sedation in this patient group has been reported on,^1,2 there are few reports in the literature on factors which may preclude successful conscious sedation. The present service evaluation aims to address this gap and determine if there are common factors in unsuccessful sedation cases.

Background 

A learning disability is defined by three core criteria: lower intellectual ability (usually an IQ < 70), significant impairment of social or adaptive functioning, and onset in childhood.³ Autism is a spectrum condition and neuro-developmental disorder characterised by a triad of lifelong impairments- social interaction, social communication and imagination.⁴

Some patients with a learning disability display challenging behaviour. This is described as ‘...culturally abnormal behaviour(s) of such intensity, frequency or duration that the physical safety of the person or others is likely to be placed in serious jeopardy’.⁵ Challenging behaviour may include aggression, disruptive or destructive behaviour. It is more common in patients with more severe disability, with rates of 30 to 40% in hospital settings.³

Clinical holding is ‘...the use of physical holds’ to ‘...assist or support a patient to receive clinical dental care or treatment in situations where their behaviour may limit the ability of the dental team to effectively deliver treatment, or where the patient’s behaviour may present a safety risk to themselves, members of the dental team or other accompanying persons’.⁶

In 1971 Healy, Edmondson and Hall assessed the use of local anaesthetic and intravenous diazepam in patients with mild to moderate LD as an alternative to GA and reported that operating conditions were acceptable in 80% of cases.⁷ Due to long waiting times and the associated GA risks, there is a move towards attempting dental treatment under conscious sedation. Oral or intranasal sedation can help improve co-operation to facilitate cannulation. Hossenally and Doughty saw a 96% success rate in cannulation over a four-year period in patients given intranasal sedation prior to attempting cannulation. 92 to 95% of treatment was completed successfully in these cases.⁸

Additionally, Manley, Ransford, Lewis, Thompson and Forbes found that 90% of treatment was completed successfully when adults with learning disabilities were treated with IN and IV sedation.⁹ However, not all patients respond favourably to this treatment modality. The challenges presented by this patient group may include unpredictability of response to sedative, limited co- operation and comprehension and challenging behaviour. In some patients, conscious sedation techniques are unsuccessful and planned treatment cannot be completed necessitating a GA.

Dental sedation success rates are reported in the literature, however, there is a lack of studies which assess the reasons for unsuccessful sedation. A study by Malamed, Gottschalk, Mulligan and Quinn reviewed 96 adults with impairments treated using a combination of intravenous drugs and reported that four of the patients were unable to be treated under sedation and were referred for GA.¹⁰ Manley, Skelly and Hamilton cited challenges such as poor cooperation with venepuncture and lack of verbal communication.¹ Other reasons cited included: refusal to accept intranasal administration, resistance to cannulation and/or treatment following intravenous administration.⁹ However, neither the behaviour of the patient nor the evolution of their psychological state over the session, were reported.²

Aims

• To evaluate the reasons for unsuccessful intranasal, oral, and intravenous conscious sedation
• To assess if there is a correlation between patient factors and sedation failure
• To identify if there are ways to improve success of conscious sedation for patients with LD and ASD.

Methodology

The clinical records of patients were retrospectively reviewed across two NHS Trusts providing dental treatment for patients with LD and ASD under sedation. Sedation cases over a 30-month period (January 2019 to July 2021) were reviewed. The inclusion criteria included patients with a LD and / or ASD for whom conscious sedation was not successful. Exclusion criteria included patients with successful sedation and those that did not have a LD or ASD. Unsuccessful sedation was defined as ‘planned treatment unable to be carried out in its entirety, not including treatment modifications’.

The following outcomes were identified for the cases where sedation was unsuccessful: diagnosis of learning disability and / or autism; history of challenging behaviour; communication; capacity to consent; medical history; ASA grade; mobility; Ellis sedation score; sedation modality; drugs and dosage used; use of clinical holding; dental treatment attempted; separate operator and sedationist; reason for sedation failure; stage at which sedation failed; and eventual outcome.

Results

A total of 452 patients with LD / ASD were treated with sedation across two Trusts (272 in Trust A and 180 in Trust B). A total of 7.5% (n = 34 patients) who fell into the above criteria, received treatment under sedation which was unsuccessful during this period. The patients were aged 14 to 55 years old, with the mean age being 25 years old. Table 1 outlines the patient demographic for those included in the failed sedation group.

The pie chart in Figure 1 outlines the documented use of clinical holding in 41% (n = 14) of patient cases, 50% of whom had a history of challenging behaviour. However, clinical holding use was not documented in 47% of cases (n = 16). In 65% of cases (n = 22) there was a separate sedationist and operator treating the patients, 50% of whom displayed challenging behaviour. In 23% of cases (n = 8) there was a single dentist working as the sedationist and operator and in 12% of cases (n = 4) this was not recorded.

The reasons for unsuccessful sedation are outlined in Figure 2. In 44% of cases (n = 15) there was insufficient co-operation for successful venepuncture, despite administration of oral or intranasal midazolam. In 38% (n = 13), excessive movements following administration of sedation meant dental treatment was unsafe and therefore abandoned. Furthermore, in one case, iatrogenic damage due to excessive patient movement necessitated additional treatment under GA. In two cases the patients were restless and pulled out the cannula. In addition to excessive movements, 9% of patients (n = 3) presented with challenging behaviour which made dental treatment impossible. Two cases were abandoned because the patient had a very short sedation window and in one case the patient’s oxygen saturation levels were unstable throughout sedation meaning that treatment was unsafe to proceed.

Figure 3 illustrates the sedation modalities utilised: 37% oral + IV midazolam; 26% IN + IV midazolam; 16% IV midazolam; 11% IV midazolam + fentanyl; 10% oral + IN + IV midazolam. The dose of IV midazolam administered ranged from 2 to 18mg, with the mean dose being 8 mg. Table 2 shows the Ellis grade recorded for the patients who underwent IV sedation.

Discussion 

According to The National Institute for Health and Care Excellence (NICE) guidelines on challenging behaviour and learning disabilities, when considering interventions clinicians should, ‘…adjust the nature, content and delivery of the interventions to consider the impact of the person's learning disability and behaviour that challenges’.³

Only 7.5% of cases evaluated were unsuccessful, which demonstrates that conscious sedation can be used to successfully manage and treat the majority of patients with LD and ASD. However, this service evaluation highlights that conscious sedation does have its limitations and outcomes can be difficult to predict.

The results demonstrate a trend in that most unsuccessful cases were male (68%), fully mobile (74%) and non-verbal (62%). Therefore, individuals with those traits could be seen as having a higher chance of their sedation being unsuccessful. A higher rate of failure was seen in males, however this may be due to more males being sedated in total. Unfortunately, we were not able to confirm this, as the sex distribution of all sedated cases was not reviewed. Therefore, further analysis and research is required to validate these findings.

6% of sedation failure was due to a short sedation window which may render extensive dental treatments unfeasible. Patients with high or complex treatment needs, such as those involving multiple restorations and extractions, surgical extractions, or root canal treatments on anterior teeth, may not always be practical under sedation due to multiple visits required, length of time required for treatment and possible deterioration of cooperation over time. This should be discussed during initial treatment planning and often a pragmatic approach with a single visit general anaesthetic should be considered in the patient’s best interest when there is a high or complex treatment need.

The outcomes of this service evaluation highlight the importance of conducting a comprehensive sedation assessment and good treatment planning for this patient group. The whole team should be briefed in the planning of these cases. This should include a safety brief, discussion of any reasonable adjustments and rehearsal of clinical holding techniques for cannulation and during treatment. A simple reasonable adjustment could be to record this patient group as high priority to avoid any delay in the scheduled appointment time, as delaying treatment can result in an escalation of challenging behaviour.

Analysis of previous sedation experience is valuable to ascertain how sedation was completed in the past, including any reasonable adjustments or adjuncts required to facilitate successful treatment. Patient factors such as benzodiazepine tolerance, challenging behaviour, anxiety level, and patient resistance to the effect of sedation, are all useful predictors of difficult sedation cases which can be obtained through a thorough behavioural and sedation history.

The Scottish Dental Clinical Effectiveness Programme guidelines for conscious sedation recommend completing a sedation assessment at a separate appointment to the sedation visit. At the assessment a ‘...thorough medical, dental, social, anxiety and sedation history’ must be undertaken ‘...to ensure that the conscious sedation technique chosen is the most suitable’.¹² This will help maximise success and anticipate any challenges. It may be helpful to consider the factors identified in this service evaluation as potential predictors of unsuccessful sedation in the sedation preassessment. However, additional studies and research are required to further evaluate and validate the findings in this service evaluation.

The reasons cited most frequently for failure in this patient group were failure to cannulate (44%), followed by movements (38%). This highlights the importance of assessment of ease of cannulation at the preassessment, as difficult venous access in combination with movement pose challenges for cannulation. The clinician may choose to ask how the patient co-operates with blood tests to determine the degree of difficulty. They may also seek the patient’s family or carer’s view on the use of clinical holding to minimise movement during cannulation.

41% of unsuccessful sedation cases had a history of challenging behaviour documented in the clinical records and 9% of unsuccessful sedation was due to patients’ challenging behaviour. Therefore, patients with a history of challenging behaviour have a higher chance of having unsuccessful sedation. Separate operator / sedationist should be advocated for cases of known challenging behaviour for safety and clinical holding reasons.^8,13 41% of unsuccessful cases required clinical holding, however, this may be under-reported as neither site included record of clinical holding in the sedation proforma. This evaluation highlights the value of training the whole sedation team in clinical holding to successfully manage patient movements to safely obtain intravenous access. The level of clinical holding and the technique used should be recorded. This will facilitate future treatment planning and is a recommendation for good practice following this service evaluation. Potential triggers for challenging behaviours and more details on the behaviours and how to help de-escalate should be part of the sedation assessment, and this should be discussed in the team safety briefing before treatment is started. Patients with LD / ASD may often present with other co- morbidities including psychiatric disorders, such as schizophrenia or bipolar disorder, and neurological conditions such as epilepsy.^14,15 Subsequent polypharmacy may mean there are multiple compounding factors affecting the outcome of sedation.

The sedation modalities used are attributed to preferences for oral and intranasal sedation which vary among clinicians and settings. There was no protocol for choice of modality used, with choice dependent on availability, training and patient / family / clinician preference. Training in the delivery of different sedation modalities, may standardise the delivery of conscious sedation in this group leading to improved success.

Conclusion 

Conscious sedation for patients with learning disabilities and autism is a safe and useful treatment modality. Multiple factors play a role in reducing the success of the sedation. Aiming to identify and minimise their effects can help improve the chances of success. Compounding factors such as high or complex treatment needs, competency of clinical team in sedation techniques, and training in clinical holding should be considered before deciding on whether conscious sedation is suitable or whether treatment should be conducted under GA. Larger scale multi-centre studies can be useful to study and establish generalised trends of sedation outcomes in patients with LD. Improved documentation of patient-related factors such as severity of learning disability and any challenging behaviour, coupled with standardised sedation outcome reporting such as Ellis grade or Ramsay score, will facilitate comparison of results across sites.

Acknowledgements 

Evidence search: QI ‘Unsuccessful Conscious Sedation in dental patients with a Learning disability and/or Autism’. Ms Assad Lahlou. (11th April, 2022). LONDON, UK: Barts Health Knowledge and Library Services.

Declarations of Interest

 The authors declare no conflicts of interest.

Author contribution statements

Service evaluation conception: JL, JJ, XY, HH. Data collection: JL, JJ, XY, HH. Paper drafting: JL, JJ, XY, HH. All authors contributed to the critical review and final approval of the paper.

References 

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