E-Book, Englisch, Band 15, 144 Seiten
E-Book, Englisch, Band 15, 144 Seiten
Reihe: QuintEssentials of Dental Practice
ISBN: 978-3-86867-369-2
Verlag: Quintessenz
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)
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Weitere Infos & Material
Chapter 01. Historical Development of Conscious Sedation
Chapter 02. Basic Physiology and Anatomy: A Whistle-stop Tour
Chapter 03. Pharmacology
Chapter 04. Initial Assessment and Treatment Planning
Chapter 05. Equipment for Conscious Sedation
Chapter 06. Clinical Techniques
Chapter 07. Complications: Avoidance and Management
Chapter 08. Sedation in Special Circumstances
Chapter 09. General Anaesthesia
Chapter 10. Standards of Good Practice and Medicolegal Considerations
Chapter 1
Historical Development of Conscious Sedation
Aim
The aim of this chapter is to describe the historical development of conscious sedation techniques for dentistry. Outcome
After reading this chapter you should have an understanding of the way conscious sedation techniques have evolved. You will also understand the close historical links between conscious sedation and general anaesthesia. Introduction
The ability of 21st century dentists to provide comfortable treatment for their patients has its origin in the discovery and development of general anaesthetic drugs in the 19th century. Before the advent of these drugs, the dental patient was expected to endure considerable pain and distress. The most commonly performed surgical procedure was the extraction of teeth. Grim stoicism and occasional self-medication with alcohol were the only ways of coping. Dentists contributed in no small measure to the early development of general anaesthesia and, later, to the introduction of local anaesthesia and conscious sedation techniques. In the USA, Horace Wells used nitrous oxide for the first time in 1844 and William Morton administered ether for dental extractions in October 1846. Both these men were dental surgeons. In England, another dentist, James Robinson, was the first to administer ether to a patient in London only two months after Morton. Carl Koller pioneered the use of topical and injected cocaine for local anaesthesia in ophthalmology in 1884. Twenty years later, procaine was available for use in dental patients. This was superseded by lidocaine (lignocaine) in the late 1940s. Reports of dentists using nitrous oxide to provide inhalational conscious sedation, rather than general anaesthesia, started to appear in the early 1900s. By the 1930s, an intravenous barbiturate, hexobarbitone, was in use in UK dental practices for sedation. Table 1-1 Chronological development of dental conscious sedation. Year Developments 1940s “Relative Analgesia” (nitrous oxide/oxygen) 1945 The Jorgensen Technique 1960s IV methohexitone (Brietal®) 1966 IV diazepam (Valium®) 1970s IV diazepam (Diazemuls®) 1983 IV midazolam (Hypnovel®) 1988 IV flumazenil (Anexate®) 1990s IV propofol (Diprivan®) Over the course of the second half of the 20th century, there were further developments in the drugs and techniques used for dental conscious sedation. These are shown in Table 1-1. Relative Analgesia
Joseph Priestley discovered oxygen in 1771 and nitrous oxide in 1772. The analgesic properties of nitrous oxide were discovered by Humphry Davy in 1798. It appears that Davy inhaled nitrous oxide in order to determine its effects, while suffering pain from a partially erupted wisdom tooth. He noticed that his painful pericoronitis was relieved. In 1800, Davy published a treatise on nitrous oxide in which he suggested that the gas “may probably be used with advantage during surgical operations”. No further progress was made until 1844, when Horace Wells had one of his own teeth extracted under nitrous oxide anaesthesia. Edmund Andrews, a Chicago surgeon, reasoned that the asphyxia often seen during nitrous oxide anaesthesia was due to the oxygen in nitrous oxide not being available to oxygenate the blood. In 1868 he demonstrated that a mixture of 20% oxygen and 80% nitrous oxide was satisfactory for safe and effective anaesthesia. In 1881, nitrous oxide was first used as an analgesic during childbirth in St Petersburg. In 1889 nitrous oxide was used to provide analgesia for a dental procedure in Liverpool. By current standards, the machines used to deliver nitrous oxide and oxygen were crude and the gases far from pure. Many dentists manufactured their own nitrous oxide. During the first half of the 20th century interest in nitrous oxide sedation came and went. Success was variable, partly as a consequence of the use of inappropriate equipment, but also because of a misunderstanding about the properties of the gas and the best way to use it. Hitherto, the main emphasis had been placed on the analgesic properties of nitrous oxide, but attempts to achieve total analgesia in every patient often led to failure. Many patients experienced nausea, vomiting and excitement-stage symptoms. Appreciation of the excellent sedative properties of nitrous oxide came later following the work of Harry Langa (USA), Ulla Holst (Denmark) and Paul Vonow (Switzerland) during the 1940s and 1950s. The change in use of nitrous oxide from analgesia to sedation led to alterations in technique, dosage and in the approach to the patient. Langa used the term “Relative Analgesia” to describe his sedation technique. The technique involved the administration of low to moderate concentrations of nitrous oxide in oxygen (using a specially designed machine) accompanied by a steady stream of reassuring and encouraging talk. The technique, with some minor modifications, has now been in use for over 50 years. Barbiturate-based Techniques
Barbiturates Key Dates
1912 phenobarbitone 1930s hexobarbitone and thiopentone 1940s The Jorgensen Technique 1960s IV methohexitone (Brietal®) The Jorgensen Technique
In 1945 Niels Jorgensen used a cocktail of intravenous agents as “premedication” for patients about to undergo dental procedures under local analgesia. The method, also known as the Loma Linda technique, took advantage of the hypnotic and tranquillising effects of pentobarbitone, the analgesic action of pethidine and the amnesic properties of hyoscine. It allowed prolonged treatment to be carried out, but the method was unsuitable for procedures lasting less than two hours. Recovery could be prolonged. Methohexitone
Barbituric acid was first prepared in 1864 by Adolph von Baeyer – a research assistant to Kekule in Ghent. The first hypnotic barbiturate, diethylbarbituric acid (barbitone), was introduced into medicine by Fischer and von Mering in 1903. Barbitone had excellent hypnotic properties and was used for many years. Phenobarbitone (Luminal) was introduced in 1912. Hexobarbitone, thiopentone and methohexitone were classified as ultra-short-acting drugs and, therefore, the most likely to be of use for dental sedation. In the 1930s, Stanley Drummond-Jackson, a Huddersfield dentist, used intravenous hexobarbitone (and later thiopentone) to produce “insensibility” in patients undergoing not only extractions, but also more lengthy conservative procedures. He used a single dose technique, which was calculated on the basis of the estimated length of the procedure. If the procedure took longer, the anaesthesia was maintained by the use of inhalational agents. The technique was satisfactory in the skilled hands of a fast worker, but there were few dentists who possessed sufficient knowledge and competence in the use of these drugs and, as a consequence, the technique did not gain popularity. The situation did not change until the introduction of methohexitone (Brietal). In the mid-1960s Drummond-Jackson pioneered a method to produce a controlled level of unconsciousness by administering increments of the drug via an indwelling intravenous needle. Drummond-Jackson’s technique became known as “ultra-light anaesthesia” or “minimal increment methohexitone”. The technique was widely adopted, especially in the UK and in the USA. It was, however, a subject of controversy, and over the next two decades an increasing amount of evidence was produced in an attempt to undermine the confidence of both the dental profession and patients. There was much discussion about whether the technique produced anaesthesia or sedation and whether protective laryngeal reflexes were dangerously compromised. There were discussions about the meaning of sedation and the definition of anaesthesia. There was polarisation of views, hostility between medical and dental anaesthetists and, finally, a lengthy and hugely expensive libel action in the UK. The outcome was a rapid decline in the use of ultra-light methohexitone in dentistry. Benzodiazepine-based Techniques
Benzodiazepines – Key Dates
1959 chlordiazepoxide (Librium®) 1966 diazepam (Valium®) 1970s diazepam (Diazemuls®) 1983 midazolam (Hypnovel®) 1988 flumazenil (Anexate®) Diazepam
Benzodiazepine compounds were first synthesised in 1933. Early animal tests indicated that chlordiazepoxide had interesting muscle-relaxant properties. In 1960 Randall reported that it produced “taming” of a number of species of animals in doses...
