February 1, 2012
by Michelle Wong, DDS, Peter Copp, DDS, BScD (Anaesthesia), FADSA
A 45-yr-old male presented for restorative treatment under deep intravenous sedation indicated by dental anxiety to the sound of the drill. The medical history included sleep apnea, depression, paranoid delusional disorder, insomnia, chronic pain from sciatica, and obesity (BMI 36.1 kg/m2). Current medications included daily use of morphine 240 mg, three tablets of Percocet, haloperidol 3 mg, amitryptyline 75 mg, zopiclone 7.5 mg and 8 cups of coffee. The patient rigidly followed preoperative instructions, ingesting no food after midnight, having only water or apple juice three hours prior to the afternoon appointment, in addition to his prescribed medications. Induction was achieved with midazolam, fentanyl, glycopyrrolate and a propofol bolus and infusion. The patient was spontaneously ventilating and the airway was supported throughout. Haemodynamics were stable throughout. Emergence and recovery was uneventful, except for postoperative headache which persisted in the evening despite administration of ibuprofen 400 mg po during the recovery period. Caffeine is a staple in Canadian culture. Approximately 14 billion cups of coffee are consumed in Canada every year.1 It has been touted as the most popular hot beverage and the number one food service beverage in Canada.1 The market is increasing with the growing market for caffeinated energy drinks. On average, consumers intake about 300 mg caffeine daily from various sources (Table 1).
Symptomatic caffeine withdrawal can be common perioperatively with procedural sedation or general anaesthesia when patients are requested to withhold food and drink. Onset of initial symptoms can present as early as 3 hours from abstinence.3 Caffeine withdrawal has been well-characterized by headache, fatigue, decreased energy and alertness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, fogginess or not clearheaded.3 Caffeine withdrawal is recognized, not only in adults, but also in adolescents and children.4,5 The incidence in teens and children may increase substantially with the growing market for highly caffeinated, easily accessible beverages;6 thus, caffeine withdrawal may even present in the paediatric practice.
Fennelly et al. hypothesized that caffeine withdrawal was a mechanism of postoperative headache. Their study’s logistic regression analysis noted that “for each 100 mg increase in caffeine consumption, there was a 16% increase in the odds of postoperative headache developing (p<0.0001).”7 Symptoms typically present within 12-24 hours.3,8
Instructions are routinely given to the patient at the preoperative assessment appointment. They clearly instruct the patient to not eat heavy meals at least 8 hours before, light meals at least 6 hours before, and not to drink 2-3 hours before procedural sedation or anaesthesia. Some clinicians simplify instructions to “nothing after midnight” or “clear fluids can be taken up until 3 hours before”. The aim of these instructions is to decrease the risk of possible aspiration of gastric contents during sedation when protective reflexes may be impaired. It is important to note that black coffee and tea as well as caffeinated energy beverages and colas are considered clear liquids. Regular caffeine consumers should be allowed or even encouraged to drink coffee before procedure to prevent postoperative headache from caffeine withdrawal within the parameters of fasting guidelines.9
Does caffeine administered perioperatively reduce the potential for postoperative headache? Research has been done to address this question.
Patients who drank caffeinated beverages on the day of surgery with general anaesthesia had a lower incidence of postoperative headaches in comparison to those who abstained (17% versus 28%; p<0.04).10
Perioperative administration of oral caffeine tablets in general anaesthetic cases has been studied.10,11 The incidence of postoperative headache was higher in patients who received placebo versus patients who received caffeine tablets preoperatively, same-day postoperatively, and postoperative day one.11 Prophylactic perioperative caffeine intake significantly reduced the incidence of postoperative headaches.11
Weber et al. performed a randomized controlled, double-blind trial with 300 adult ambulatory surgical patients and found that those who received prophylactic administration of 200 mg caffeine intravenously were less likely to have postoperative headache than patients who received placebo – 10% versus 2% (p<0.05).12 Moreover, the study had groups of patients who “self-treated” by allowing intake of caffeinated beverage after their surgical procedures. The group who had at least one caffeinated beverage and placebo approached statistical significance (p<0.06). Interestingly, the group that drank caffeinated beverages and received intravenous caffeine was not significantly different from the placebo group. Authors attributed this unexpected effect to multifactorial causes of postoperative headaches independent of caffeine intake.
It may be prudent to encourage patients who have high daily intakes of caffeine to drink black coffee or other clear caffeinated beverages 2-3 hours before their procedural sedation or anaesthetic to prevent the onset of postoperative headache. While concerns that patients may not follow pre-op instructions (for example, have cream or milk in their tea or coffee) may exist, patients can be encouraged to consume alternative caffeinated beverages if they do not wish to drink their coffee or tea without dairy products or other ‘creamers’.
Caffeine tablets that contain 100 mg as premedication may be an option as prophylaxis against caffeine withdrawal. Caffeine is available as 100 mg tablets in Canadian pharmacies as an over-the-counter product.
Intravenous caffeine preparations have limited availability in Canada compared to the United States. Given that caffeine base is only slightly soluble in water, various synthetic mixtures have been made to increase solubility. Commercially available caffeine sodium benzoate is one form, whereas caffeine citrate is only available in powder form. Twenty milligrams per kilogram of caffeine citrate or benzoate is equivalent to 10 mg/kg of caffeine base. Caffeine base for intravenous use can be prepared from caffeine citrate. In Canada, a parenteral formulation can be prepared by reconstituting caffeine citrate powder in sterile water but compounding requires sterile technique (including microfilter and autoclave procedures required for injectable form) which is achievable in the hospital setting.
Postoperative intake of coffee may also help alleviate withdrawal symptoms. Generally, (independent of anaesthesia), low to moderate doses of caffeine (20-200 mg) produce reports of increased well-being, happiness, energy, alertness, and sociability.3 In-office complimentary caffeinated beverages provided after the appointment may improve patient satisfaction.
The postoperative experience of deep sedation or general anaesthesia is altered by caffeine withdrawal. Clinicians who administer any form of sedation should be aware of the signs and symptoms, particularly postoperative headache. Counselling the patient on this effect prior to the appointment may minimize postoperative management and dissatisfaction with sedation. Perioperative caffeine administration can be considered for anticipated caffeine withdrawal. OH
Dr. Michelle Wong is a first-year resident in Dental Anaesthesia at the Faculty of Dentistry, University of Toronto.
Dr. Peter Copp is a certified specialist in dental anaesthesia in private practice and teaches at the Faculty of Dentistry, University of Toronto.
Oral Health welcomes this original article.
1. The Canadian Coffee Industry – Agriculture and Agri Food Canada (October 2010), Updated 2011-01-25. Accessed 2011-10-20, fr
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