CLINICAL LAURA FEE Suitability of patients for conscious sedation Dentists have to consider carefully a wide range of health conditions before deciding on the appropriate approach for those that need to be sedated Dr Laura Fee atients suitable to undergo General health suitable for IV/inhalation conscious sedation (CS) considerations sedation in primary care P include those with ASA Physical Status Classification3 • ASA 3 – Patient with severe moderate-severe anxiety, a • ASA 1 – Heathy person – systemic condition – significant swallow/gag reflex or a mild suitable for IV/inhalation functional limitations such as learning/physical disability such sedation with COPD – may be suitable as cerebral palsy. Well-controlled • ASA 2 –Patient with mild for inhalation sedation in medical conditions such as asthma, systemic condition – mild primary care, but otherwise epilepsy, gastro-oesophageal reflux disease with minimum careful evaluation for hospital- and mild hypertension are functional limitation – generally based sedation exacerbated by stress, making • ASA 4 – severe systemic disease CS hugely beneficial. 1 constantly threatening life – Hospital-based intravenous About the author myocardial infarction or stroke (IV) CS helps patients with severe <six months ago – anaesthetist- systemic disease or disability led team to avoid unnecessary general • ASA 5 – Moribund. anaesthesia (GA). However, a small percentage of patients will Age still simply not tolerate dental Age is not an absolute treatment without being ‘knocked contraindication to sedation but out’, making GA essential to older patients are more sensitive 4 facilitate dental treatment. Dr Laura Fee graduated with an to sedatives. The incidence of An in-depth medical, dental honours degree in dentistry from delirium following treatment with and social history is mandatory Trinity College, Dublin, where she midazolam was 10 per cent higher at a visit before treatment. It is was awarded the Costello medal for in the elderly.5 Elderly patients also important to ascertain the patient’s undergraduate research on cross- tend to have poorly tethered, friable degree of dental anxiety. This helps infection control procedures. She is a veins, which may be more determine the most suitable member of the Faculty of Dentistry at susceptible to cannulation damage. the Royal College of Surgeons. She has sedation technique as some IV sedative agents in children <12 is a Certificate in Implant Dentistry from patients with severe needle phobia Northumberland Institute of Oral not recommended unless provided are unable to tolerate cannulation Medicine and has been awarded the by a paediatric specialist. making inhalation sedation the best Diploma in Implant Dentistry with the Disinhibition in adolescents is option for them.2 Royal College of Surgeons Edinburgh. common and even slight over- 37 CLINICAL LAURA FEE sedation can lead to rapidly heart rate = RPP, which is a reliable Post MI deteriorating respiratory indicator of myocardial oxygen At six months post-infarction depression.6 consumption. Ischemic changes a patient is classed as ASA 3. The were demonstrated in patients with risk of re-infarction is 16 per cent. Cardiovascular System an RPP of >12,000, increasing their Elective sedation in well-controlled (See table below). CS risk. The pressure rate quotient, patients reduces stress, helping to which is mean BP divided by heart lower risk. There should be no elective surgery rate, also assesses a patient’s if the diastolic value is >110 mmHg. suitability for CS. The results of this Post-percutaneous coronary However, when measuring blood study indicated that treatment with intervention (PCI) pressure always consider the risk midazolam and epinephrine does Patients must wait three months of “white coat hypertension”. not generate significant ischemic after stenting before elective Patients with controlled/ risk. It is important that the lowest sedation. Angina must always uncontrolled hypertension have a effective dose of local anaesthetic be successfully controlled more labile haemodynamic profile containing epinephrine is used before treatment.1 during CS making hypotensive and that intravascular injections swings more likely.7 are avoided.10 Classification of cardiac It has been shown that there functional reserve capacity is little evidence that a BP < NYHA classification of angina • Class 1: Able to climb a normal 180mmHg/110mmHg causes 0 healthy flight of stairs without stopping. perioperative complications. 1 no hindrance to normal Can continue walking with no However, a BP>180/110mmHg is physical exertion rests – safest for IV CS linked to perioperative ischaemia, 2 slight limitation, angina with fast • Class 2: Climbs without rest. arrhythmias and cardiovascular walking, ascending Rests on top – safest for IV CS lability. There is no clear evidence stairs, excitement • Class 3: Climbs with rest during that deferring anesthesia lowers 3 significant limitation of regular ascent – outpatient CS unsuitable perioperative risk. The movement. Angina on climbing • Class 4: Unable to climb stairs. intraoperative BP should be within normal staircase 20 per cent of best BP estimate.8 4 angina with minimal activity/rest. Patients with palpitations Dentists must evaluate pre- Patients with benign palpitations operatively for the presence of target Increased stress levels exacerbate benefit from the stress reduction organ damage such as coronary angina, making sedation and good produced by CS. A patient with artery disease. Target organ damage local anaesthesia important in malignant palpitations, however, lowers the treatment thresholds for reducing heart rate. must be treated in hospital. Any raised BP.9 Unstable angina contraindicates individual with an automated A study examining the elective treatment. Patients with implantable cardioverter- cardiovascular effects of angina that affects normal daily defibrillator is unsuitable for epinephrine with IV midazolam activity such as NYHA 3 are treatment in primary care. A examined 75 patients with heart unsuitable for sedation in primary hospital setting is mandatory for disease treated in two groups. care. If the GP/cardiologist patients with a pacemaker or those The rate-pressure product (RPP) confirms stability of angina then following AV node/conduction was used to indicate myocardial NYHA patients can progress pathway ablation surgery. ischemia. This is the systolic BP x with elective sedation.11 Wolff-Parkinson-White syndrome is an absolute contraindication to sedation.1 Cardiovascular System ASA According to Blood Pressure (BP): Respiratory disease Midazolam has a greater effect on <140 systolic and <90 diastolic ASA I Primary care suitable the respiratory system compared to 140-160/90-94mmHg ASA II Primary care suitable the cardiovascular system. Healthy 160-199/95-115mmHg ASA III Specialist unit patients who present with respiratory infections on the day 200 systolic and >115 diastolic ASA IV In-patient services of treatment should be rescheduled. 38 IDM FOR MORE CLINICAL IRELANDSDENTALMAG.IE Careful assessment of the patient’s Renal system impairment phenytoin can increase or decrease disease and functional reserve will Hepatic microsomal oxidation plasma concentration of sedatives.11 indicate the most suitable setting is responsible for midazolam’s Recovered stroke victims may for CS. It must be remembered biotransformation. This is experience a re-emergence of that opioids act synergistically susceptible to factors such as old symptoms when benzodiazepines with sedation with regards age, hepatic cirrhosis and drugs are administered. Light sedation to respiratory depression.12 (cimetidine) as they reduce the can trigger a re-occurrence of oxidative capacity. A high regular symptoms such as right-sided Dyspnoea grading system12 intake of alcohol increases paralysis and dysphasia. Sedation 0 Healthy midazolam clearance. is contraindicated for one year after 1 Mild dyspnoea Renal failure causes a build- a stroke.15 2 Moderate – limited outdoor up of metabolites which prolongs movement – hospital sedation. CS is contraindicated Haematological disorders management safest in cases of advanced liver disease.1 Sedation should be avoided in 3 Marked dyspnoea on minimal Patients undergoing patients with sickle cell anaemia exertion indoors – unsuitable haemodialysis or continuous and thalassaemia. This cohort are for outpatient sedation ambulatory peritoneal dialysis are high risk for reduced oxygen tension 4 Dyspnoea while resting – unsuitable for sedation. with respiratory depression or unsuitable for outpatient Haemodialysis patients swing over-sedation. Inhalation sedation sedation. from being centrally underfilled is preferred.16 where they are at risk of Asthma hypotension to centrally overfilled. Pregnancy The dentist must ensure the Day 2 is considered the safest time The second trimester is the safest asthmatic is well controlled. A mild to treat but outpatient CS is still time to treat, but the mother’s asthmatic is considered ASA 2; best avoided. Post-renal metabolism is altered due to the however, an untreated Grade 2 transplant patients with good increased demands of the baby. is unsuitable for treatment in renal function may be suitable for This makes sedation unpredictable. primary care. Hospital hospital-based CS.11 There are also foetal teratogenic management is necessary for Methadone and midazolam are risks.12 ASA 3 patients who have frequent both metabolised by the cytochrome episodes/attacks. It must be borne P450