Divers who fail to exhale periodically via the nose into their face mask during descent may develop \200\230face mask squeeze \200\231 (skin barotrauma). Erythema, bruising, and pet echial and conjunctival hemorrhages develop in the enclosed area. Skin tightly enclosed by parts of the diving suit can have similar appearances. Usually no treatment is required. Ascent barotrauma is the reverse of squeeze, and particularly affects the lungs. It may be caused by breath-holding during rapid uncontrolled ascent or by air trapping in patients wi th asthma or congenital lung bullae. Mediastinal emphysema is the commonest event and prese nts with i hoarseness, neck swelling, and retrosternal chest discomfort. Symptoms usually r esolve spontaneously with high concentrations of O 2 . Pneumothorax is a potentially life-t hreatening complication if it develops during the dive, as the intrapleural gas cannot be v ented and increasing ascent will precipitate tension. Conventional treatment by needle deco mpression, aspiration or chest drain insertion ( b p.336) is required. Dental pain may occur on ascent or descent in carious teeth or those which have had recent \201 llings. The affected tooth is tender on tapping. Treat symptomatically with analgesi cs and arrange dental referral. 261 DIVING EMERGENCIES: 1 Table 6.1 Sources of advice on diving emergencies and hyperbaric chambers England, Wales, Northern Ireland Diving Incident Telephone Advice Line, Institute of Naval Medicine Gosport, Hampshire Telephone 07831 151523 (24 hrs) Ask for Duty Diving Medical Of \201 cer Diving Diseases Research Center Telephone 01752 209999 (24 hrs) Ask for the Duty Diving Doctor Plymouth www.ddrc.org Scotland Hyperbaric Medicine Unit Aberdeen Royal In \201 rmary www.hyperchamber.com Telephone 0845 408 6008 State \200\230diving emergency \200\231. Give your name and teleph one number. Ask for the Duty Hyperbaric Doctor In the event of any dif \201 culties in contacting these agencies in the UK, telephone 999 and ask for COASTGUARD Other countries Divers Alert Network DAN Diving Emergency Hotline (USA) + 1 919 684 8111 www.diversalertnetwork.org This has links to diving emergency contact numbers throughout the world Further information Diving and Hyperbaric Medicine Division, Institute of Naval Medicine (G osport, Hampshire, England) . http://www.royalnavy.mod.uk/training-and-people/rn-life/medical-branch/institute -of- naval-medicine/diving-and-hyperbaric-medicine-division-dhmd/ Diving Diseases Research Center (Hyperbaric Medical Center, Plymouth, England) . www.ddrc.o rg British Hyperbaric Association . www.hyperbaric.org.uk/ Scottish Diving Medicine . www.s dm.scot.nhs.uk Divers Alert Network . www.diversalertnetwork.org 262 CHAPTER 6 Environmental emergencies Diving emergencies: 2 Decompression illness There are two forms of decompression illness. T he \201 rst occurs when dissolved nitrogen in blood and tissues is not expelled at a suf \201 cient rate to prevent bubble formation. The second occurs when air bubbles are releas ed into the circulation because of pulmonary barotrauma. This follows if air bubbles enter the pulmonary capillaries from ruptured alveoli. The bubbles travel via the left side of th e heart to the systemic circulation. Cerebral air embolism usually causes symptoms as the d iver surfaces, with loss of consciousness, \201 ts, cardiovascular collapse and chest pai n. Clinically, differentiation between the two forms is dif \201 cult and initial manageme nt is the same. In general, the sooner the onset of symptoms, the greater the likely severi ty. Symptoms may be attributed by the patient (and the unwary doctor) to musculoskeletal sp rains/strains or other minor injury. Decompression illness is more likely in divers who have not followed safe ascent recommenda tions, the obese, in cold water, and when excessive exercise has occurred during the dive. It may be precipitated by air travel if insuf \201 cient time is left between diving and \202 ying for residual nitrogen to leave the body in a controlled fashion. Bubbles have di rect mechanical and local in \202 ammatory effects, commonly involving joints, skin, CNS, lungs and ears. Joint pain, \200\230the bends \200\231, most often affects shoulders and elbows. A dull ac hing sensation, i by movement but without localized tenderness is common. Pruritic rashes, local swelling and a peau d \200\231orange effect may occur. Back pain, limb weakness, sens ory abnormalities or urinary retention imply spinal cord involvement. Central effects inclu de focal de \201 cits, cerebellar disturbance and mood changes. Treatment for decompression illness is recompression. If delayed, risks of permanent damage to brain and spinal cord greatly i . The diagnosis of decompression sickness may only foll ow the response to recompression. Pending this, give the highest possible concentration of O 2 . Analgesics and sedatives can mask recompression responses and should only be used on specialist advice. Entonox is absolutely contraindicated. If intubation is required, in \202 ate the ET tube cuff with sterile water, since during r ecompression an air- \201 lled cuff will de \202 ate. IV \202 uids (0.9 % saline or a p lasma expander) assist oxygenation of ischaemic tissues and facilitate discharge of excess tissue nitrogen load into the venous system by ensuring adequate circulating volume. Some c enters may recommend aspirin and/or dextran solutions to d capillary sludging which accompa nies severe decompression sickness. Despite dry or wet suits, hypothermia is common. Treat with appropriate passive or active r ewarming ( b p.256). 263 DIVING EMERGENCIES: 2 Air evacuation If, after consultation with the diving medical center, air evacuation is nec essary, unpressurized aircraft should not \202 y above 300m. The diver should breathe 100 % O 2 . On reaching the diving center, recompression to a simulated depth of 18m with 100 % O 2 occurs, interspersed with periods of air breathing to d O 2 toxicity risk. Slow decom pression then follows standard treatment protocols. Divers usually dive in pairs. If a diver has symptoms of decompression sickness or pulmonar y barotrauma, his \200\230buddy \200\231 will be at risk also. Although recompression may not be required in the buddy, transfer him/her along with the affected diver and their divi ng equipment to the recompression facility. Obtain the following information before referral, if possible: \200 The patient \200\231s current condition, progression since onset, and response to treatment. Time of onset of symptoms related to the dive. \200 Dive pro \201 le and history (depth, duration, activity during the dive, speed of ascent including details of any stoppages, en vironmental conditions (water temperature, currents, etc.), pre-dive exercise, alcohol, dru gs and food, type and condition of diving equipment used, clothing worn, other recent dives ). Many divers store much of this information in a dive computer. Previous medical history, previous diving-related episodes, drug history. 264 CHAPTER 6 Environmental emergencies Heat illness Body T is normally kept at 36 \200\22338 C by homeostatic mechanisms whi ch are controlled by the hypothalamus. Hyperthermia occurs when these mechanisms are overwh elmed by factors acting individually, or (commonly) together. These conditions can occur ev en in temperate climates. At-risk groups include the young and the elderly in conditions of i temperature and humidity, and patients with unaccustomed or prolonged muscular activity (eg at \200\230raves \200\231, associated with ecstasy or other drugs), grand mal \201 t ting, athletes, marathon runners and armed forces recruits. Predisposing medical factors include \200 Alcohol use or withdrawal (including delirium t remens). \200 Cardiac disease. \200 Any condition which may cause or aggravate Na + /H 2 O loss (eg gastroenteritis, cystic \201 brosis). Drugs, including: alcohol, diuretics, salicylates, anticholinergics (antihis- tamines, tric yclic antidepressants), sympathomimetics (amphetamines, ecstasy, LSD, cocaine, phencyclidin e, appetite suppressants), phenothi- azines, antipsychotics, MAOI, SSRI. Heat illness has a spectrum of severity: Heat cramps \207\224 Heat exhaustion \207\224 He at stroke In heat cramps/exhaustion , homeostatic mechanisms still function, but are overwh elmed. In heat stroke , all thermoregulatory control is lost, body temperature i rapidly to very high levels ( > 41 C) causing widespread severe tissue and organ damage. Mortality may exceed 10 % . Heat cramps Core T of 37 \200\22339 C. Mental function is normal. Sweating during exe rcise and replacement with hypotonic \202 uid leads to Na + de \201 ciency. Brief cramps occur in muscles used in heavy work, usually after exertion. Heat exhaustion Core T <40 C. Mental function is normal. Characterized by mixed Na + /H 2 O depletion. Sweating and tachycardia are usually present. Symptoms of weakness, fatig ue, headache, vertigo, nausea and vomiting, postural dizziness, syncope. Patients will reco ver with rest and \202 uids. In mild cases , remove from heat and use simple cooling tech niques. Rehydrate with oral electrolyte solutions. More severe cases require IV 0.9 % salin e or 0.45 % saline/5 % dextrose. Use clinical assessment, U&E and haematocrit to guide infu sion rate. Up to 4L of \202 uid may be required over 6 \200\22312hr. Avoid over-rapid inf usion which may cause pulmonary and/or cerebral oedema. Measurement of core temperature Tympanic or rectal T measurement is appropriate in the E D, but may underestimate core T and respond slowly as this changes. Oesophageal and intr avascular probes give the most accurate readings of core T but require special equipment . 265 HEAT ILLNESS Heat stroke Suspect in collapse during or after exercise and in high risk groups. Core T is > 41 C (but signi \201 cant cooling can occur before arrival in the ED). There is m ulti-system damage especially to the CNS. Outcome depends upon the height and duration of i T . Mortality is 8 10 % . \200 CNS : oedema + petechial hemorrhages cause focal/gener alized damage. \200 Muscle injury releases enzymes, myoglobin, urate, K + , PO 4 3 \200 \223 . \200 Liver : damaged cells release enzymes. Jaundice commonly develops after 24hr. Kidneys : ARF from hypovolaemia, muscle breakdown products, acidosis, DIC. Blood : DIC, thrombocytopenia, leucocytosis. \200 Metabolic : i or d K + , metabolic acid osis, respiratory alkalosis, hypoglycaemia. Features Sweating may be present. The skin surf ace may feel deceptively cool due to peripheral vasoconstriction. \200 CNS : confusion, d elirium, \201 tting, coma, oculogyric crisis, dilated pupils, tremor, muscle rigidity, de cerebrate posturing, cerebellar dysfunction. CVS : tachycardia, hypotension, arrhythmias. \200 Coagulopathy : purpura, conjunctival he morrhages, melaena, haematuria. Investigations ABG, U&E, BMG, CK, clotting screen, LFTs, ur ate, Ca 2 + , PO 4 3 \200\223 Treatment \200 Rapid therapy is vital. Do not wait for the results of investigations. \200 Remove the patient from the hot environment and remove a ll clothing. \200 Secure the airway (intubation and IPPV if needed). Give high FiO 2 . \200 Cooling techniques depend upon facilities available and the clinical state of the pat ient. Do not give \200\230antipyretics \200\231 such as aspirin/paracetamol. Evaporative c ooling is the most ef \201 cient and applicable treatment. Spray the naked patient with te pid tap water and blow air over the body with fans. Ice-packs can be applied to the axillae , groins, neck, and scalp (but avoid prolonged contact). Consider cold gastric or peritonea l lavage, or cardiopul- monary bypass if these techniques fail. Aim for cooling rate of at least 0.1 C/ min. When core T <39 C stop active cooling as hypothermia may develop . \200 IV \202 uids: give 50mL 50 % dextrose IV if BMG <3mmol/liter. Severe hypo- volae mia is uncommon. If hypotension persists despite d T , give IV 0.9 % saline (1 \200\2231 .5L over 1 \200\2232hr). Avoid overloading circulation with risk of pulmonary/cerebral oede ma. CVP monitoring may be needed. CVP may be initially i due to peripheral vasoconstriction . , ECG, CXR. Insert a urinary catheter. If myoglobinuria is present, aim for i urine output, and consider giving IV bicarbonate and/or mannitol. If \201 ts occur, give IV lorazepam \200\224 but beware of respiratory depression. Neuro leptic malignant syndrome is an idiosyncratic reaction in patients on antipsychotics (espec ially haloperidol, thioridazine, chlorpromazine). Features are muscle rigidity, extrapyrami dal signs, autonomic dysfunction, severe dyskinesia. Stop the antipsychotic, cool the patie nt, and give dantrolene. Malignant hyperpyrexia is a rare autosomal dominant condition rela ted to use of suxamethonium and volatile anesthetics. Dantrolene prevents Ca 2 + release fr om skeletal muscle and is very effective: initial dose is 2 \200\2233mg/kg IV, then 1 mg/kg as needed, max total dose 10 mg/kg. See guidelines: www. aagbi.org/publications/guidelines /docs/malignanthyp07amended.pdf 266 CHAPTER 6 Environmental emergencies Electrical injuries An electric shock can cause cardiac and respiratory arrest. The heart o ften restarts spontaneously, but the respiratory arrest may be prolonged, causing fatal hyp oxia. Thermal injury from the electric current produces burns and muscle damage. Muscle spa sms from a shock may result in dislocations or fractures or precipitate a fall causing majo r trauma. Fatal electrocution can occur from domestic electricity (in the UK 230 volts, alt ernating current at 50cycles/sec), but severe injury is more common with high voltage shock s ( > 1000V). Lightning causes a direct current (DC) shock at a very high voltage (up to 100,000,000V), b ut short duration (0.1 \200\2231msec). Electrical \202 ash and arc burns An electrical short-circuit near to a person may cause sudden vaporization of metal and deposition of a thin layer of hot metal on the skin, witho ut any electricity passing through the casualty. Electrical \202 ash burns may look drama tic because of discolouration of the skin, but are often super \201 cial and heal uneventf ully. In contrast, electrical arcing produces high temperatures, and may cause deep dermal or full thickness burns, especially if clothing is set alight. Contact burns If electricity has passed through the patient there are usually two or more e ntry or exit wounds, which are full thickness burns with white or charred edges. Tissue dam age is more extensive than the visible burns, especially with high voltage injuries. Deeper layers of skeletal muscle may be involved and muscle damage can cause myoglobinuria and re nal failure. Myonecrosis and oedema of muscles may produce a compartment syndrome ( b p.398 ). If current passes through the torso, cardiac arrhythmias are more likely than if only a single limb is involved. Myocardial damage may occur, often in association with vascular in juries. Neurological effects of electric shocks include coma, \201 ts, headaches, transient paral ysis, peripheral neuropathy, and mood disturbances. Ophthalmic injuries are common after electrical burns of the head. Cataracts and glaucoma m ay develop later. Electrocution in pregnancy has major risks for the fetus (spontaneous abortion has been rep orted). Obtain obstetric advice. Lightning The sudden vaporization of sweat and rain water caused by lightning may explode c lothes and shoes off the victim and rupture ear drums. Lightning burns are super \201 cial , often with a characteristic feathered or fern-like appearance. The limbs are often cold a nd mottled due to arterial spasm, which usually resolves over a few hours. Deep muscle dama ge and myoglob- inuria are rare. Coma may result from direct brain injury, head injury due to a fall, or cardiac arrest. CPR, if indicated, may be successful even if required for pro longed periods. Survivors may be confused and amnesic for several days and may have \201 ts and temporary paralysis. Cataracts are common. 267 ELECTRICAL INJURIES Management \200 At the scene, make sure that the current is turned off before anyone appr oaches or touches the casualty. Remember that high voltage elec- tricity can arc through th e air or pass through the ground. Check the airway, breathing and circulation. Electrical burns of the mouth and throat may cause oedema and airway obstruction. Perform CPR if necessary, but minimize movement of the spine in case of trauma. Examine thoroughly for head, chest, abdominal and skeletal injuries. \200 Examine all ove r for skin entry/exit burns, and check pulses and sensation. Check the ECG: there may be arrhythmias (eg atrial \201 brillation), conduction defects, ST elevation and T wave changes. Check FBC, U&E and creatine kinase (except in minor low-voltage burns). Test the urine for blood. If the stick test is + ve for blood, but there are no red blood c ells on microscopy, treat for myoglobinuria to prevent renal failure: obtain specialist adv ice, maintain a high urine output, and consider using mannitol isotonic sodium bicarbona te. Fluid loss into muscles results in hypovolaemia: IV \202 uids are often required. After h igh voltage injuries, widespread fasciotomies may be needed, with excision or amputation of non-viable tissues and inspec- tion and further debridement after 48 hours. Admission It is reasonable to allow home asymptomatic patients with domestic and minor low voltage burns, a normal ECG, no history suggestive of arrhythmia (eg palpitations) and no m yoglobinuria, but advise review if any problem develops. Admit children who bite electric \202 exes for observation, because of the risk of delaye d bleeding from labial blood vessels. Many patients with electrical injuries will need admission for observation and monitoring. Admit all patients with high voltage conduction injuries, cardiac arrhythmias, chest pain o r ECG abnormalities, vascular injury or myoglobinuria. 268 CHAPTER 6 Environmental emergencies Radiation incidents In the UK, 24 hour advice and assistance is available via NAIR (Nationa l Arrangements for Incidents involving Radioactivity) on telephone 0800 834153 or via the p olice. Try to distinguish between external irradia- tion of a person and contamination with radioactive material. Someone exposed to X-rays or to gamma rays in a radiation sterilizin g unit receives no further radiation after removal from the source, and there is no risk of contaminating anyone else. However, a person contaminated with radioactive material is sti ll exposed to radiation and needs urgent, careful decontamination to minimize the risks to himself and to other people. Some hospitals are of \201 cially designated for the care of casualties contami- nated with radioactive substances, but in an emergency a patient may be taken to any ED, where a plan for such events should exist. Anticipation of a radiation accident \200 Inform the ED consultant on duty immediately if a patient from a radiation incident arrives or is expected. Get advice and help from a radiation physicist (from Medical Physics or radiotherapy department). Implement the appropriate Radiation Incident Plan to deal with the patient. \200 Expect m edia enquiries. Treatment of contaminated casualties Where possible, in a designated decontamination room. This room should have a separate entrance, ventilation arrangements, decontamination facili ties with shower, and contaminated water collection facilities. Cover the \202 oor of thi s room and entrance/exit corridors with disposable sheeting. All staff must themselves be d econtaminated and checked before leaving this area. \200 Turn off air conditioning. \200 Pregnant and potentially pregnant staff should not be involved. \200 Provide any necess ary life-saving treatment, but avoid spreading treatment should take place contamination. \200\230Barrier nurse \200\231, as for an infectious disease. \200 Assume patients are c ontaminated until they have been checked by the radiation physicist. Instruct patients and staff not to eat, drink, or smoke. \200 Involve the minimum number of staff, who should wear facemasks, theater clothing with impermeable gowns or plastic apr ons, two pairs of gloves, and overshoes or rubber boots. Restrict and record movements of people in and out of the room. \200 Ensure that the ambu lance crew waits for monitoring of themselves and their vehicle. Keep everything that may be contaminated for radiation testing. \200 Collect the patient \200\231s clothes, dressings, swabs, and any equipment used in plastic bags, and keep them in the decontamination room. All blood/urine samples must be specially labeled and the laboratories informed of the radiation risk. Life-threatening injuries may take precedence over all of the above, such that patients may need to be managed in the resuscitation room. 269 RADIATION INCIDENTS Decontamination of the patient The radiation physicist should determine the sites of contam ination and monitor the effectiveness of treatment. The object is to remove any contaminati ng substance and minimize absorption into the body, especially via the mouth, nose, and wou nds. \200 Cover any wounds prior to decontamination. \200 Avoid splashing. \200 Radio active material can usually be removed from intact skin by washing with soap and water. Gen tle scrubbing may be needed, but it is impor- tant to avoid damaging the skin. Carefully cl ean wounds and irrigate with water or saline. Clean the mouth using a mouthwash and a soft toothbrush, with care to avoid swallowing any \202 uid. Instruct the patient to blow their nose into paper handkerchiefs. If the nose is still contaminated irrigate it with small amounts of water. Irrigate each eye from the medial side outwards to avoid draining contaminated water into the nasolacrimal duct. Clean the hair by washing with shampoo and by clipping if contamina- tion persists, but do not shave the scalp. If monitoring shows that all contamination has been removed, treat the patient as for an ir radiated, but uncontaminated patient. However, if contamination persists, or if radioactive material has been ingested or inhaled, further treatment will be needed after discussion w ith a radia- tion specialist. Check all staff involved in treating the patient for radioactive contami- nation before they leave the treatment area. The irradiated patient A patient who has been irradiated or contaminated with radiation may be at risk of radiation sickness or other ill effects. Admit to a designated unit for asse ssment and follow-up by a radiotherapist or other specialist. Initial symptoms of radiation sickness are malaise, nausea, vomiting, and diarrhea, starting a few hours after exposure. There is then a latent period before the main effects of radiation sickness appear. Record any symptoms and the time of onset. The effects of anxiety and stress may be similar to th e early features of radiation sickness. Take blood for FBC, U&E, and blood group, recording the time on the blood tubes and in the notes. Measurement of the lymphocyte count and anal ysis of chromosomes at known times after exposure are helpful in assessing the amount of ra diation received and determining the prognosis. A low (<1.0 \227 10 9 /L) or falling lymph ocyte count indicates serious radiation exposure. Further information Radiation incidents http://www.hpa.org.uk/Topics/Radiation/Understandin gRadiation/ UnderstandingRadiationTopics/RadiationIncidents/incid_Nair/ www.hpa.org.uk (Hea lth Protection Agency). Deliberate release and CBRN incidents (see also b p.210) www.hpa.or g.uk/emergency/CBRN.htm This page intentionally left blank 271 Chapter 7 Analgesia and anesthesia Pain relief Analgesics: aspirin and paracetamol Analgesics: NSAIDs Analgesics: opioids Anal gesics: Entonox and ketamine Analgesia for trauma Analgesia in speci \201 c situations Local anesthesia Local anesthetic toxicity General principles of local anesthesia Topical a nesthesia Local anesthetic administration Bier \200\231s block Local anesthetic nerve block s Digital nerve block Nerve blocks at the wrist Nerve blocks of forehead and ear Dental ane sthesia Intercostal nerve block Femoral nerve block Nerve blocks at the ankle Sedation Gene ral anesthesia in the emergency department Emergency anesthesia and rapid sequence inductio n Dif \201 cult intubation General anesthetic drugs 272 274 275 276 278 279 280 282 284 286 288 289 290 292 294 296 300 302 303 304 306 308 310 312 314 316 272 CHAPTER 7 Analgesia and anesthesia Pain relief Many patients who come to the ED are in pain. Knowledge of the site and charact eristics of the pain is often important in diagnosing the problem. Relief of pain is an ess ential and urgent part of treatment. Pain and distress may prevent patients giving useful d etails of history and symptoms and may not allow them to co-operate with investigations or treatment. Methods of pain relief Relieving pain often requires analgesic drugs, but other types of tr eat- ment are sometimes more important. If an injury is more painful than expected consider the possibility of infection (eg necrotizing fasciitis, b p.234) or vascular compromise. S evere pain despite immobilization of a fracture suggests a vascular injury, compartment syn drome ( b p.398) or a tight plaster ( b p.424). Re \202 ex sympathetic dystrophy (Sudeck \200\231s atrophy) may also cause severe pain starting a few days after relatively minor tr auma. Splintage Immobilization of a fracture helps to relieve pain and d requirement for analgesi c drugs. Inhalation analgesia with Entonox ( b p.278) is often helpful while the splint or cast is being applied. Elevation Many limb injuries produce considerable swelling, which causes pain and stiffness . Elevate the limb to d swelling, relieve the pain, and allow mobilization as soon as possi ble. Cold Cool burns as soon as possible, usually in cold water, to relieve the pain and stop an y continuing thermal injury. Chemical burns from hydro \202 uoric acid ( b p.397) are ofte n extremely painful and need prolonged cooling in iced water. Pain from recent sprains and muscle injuries may be d by cooling with ice-packs (or a pack of frozen peas) applied for 1 0 \200\22315min at a time, with a piece of toweling between the ice-pack and the skin. Heat Pain following sprains and strains of the neck, back, and limbs is often caused by mus cle spasm. It may be eased by heat from a hot bath, hot water bottle, or heat lamp. Dressings Pain from minor burns and \201 ngertip injuries often resolves after a suitable dressing is applied. Local anesthesia (LA) LA provides excellent pain relief for fractured shaft of femur ( b p. 304, 472) and for some \201 nger and hand injuries ( b p.292). Strongly consider giving a nalgesia with LA before obtaining X-rays. Check for any possible nerve injury before inject ing LA. 273 PAIN RELIEF De \201 nitive treatment Reducing a pulled elbow or trephining a subungual haematoma usual ly gives immediate relief of pain, so no analgesia is needed. Psychological aspects of pain relief Anxiety and distress accompany pain and worsen patient s \200\231 suffering. Psychological support is needed, as well as physical relief from pain . Patients are helped by caring staff who explain what is happening and provide support and reassurance. The presence of family members or a close friend is often helpful. Analgesics Many different analgesic drugs are available, but it is best to use only a few a nd become familiar with their actions, dosages, side effects, and contrain- dications. Most hospitals have analgesic policies and limit the choice of drugs which may be used. Before prescribing any drug, check what treat- ment has been given. The patient may already be tak ing analgesia or have supplies at home. Many drugs interact with others: important drug int er- actions are listed in the BNF . Ask about drug allergies and record them. Before giving aspirin or NSAIDs ask and record about indigestion, peptic ulceration and asthma. 274 CHAPTER 7 Analgesia and anesthesia Analgesics: aspirin and paracetamol Aspirin Aspirin is a good analgesic for headaches, musc uloskeletal pain and dysmenorrhea, and has antipyretic and mild anti-in \202 ammatory acti ons. It interacts with warfarin, some anticonvulsants and other drugs, and may exacerbate a sthma and cause gastric irritation. \200 Do not use aspirin in children <16 years or duri ng breast feeding. \200 Adult dose PO is 300 \200\223900mg 4 \200\2236 hourly (max 4g dai ly). Paracetamol ( \200\230acetaminophen \200\231 in USA) Paracetamol has similar analgesic and antipyretic actions to aspirin, but has no anti-in \202 ammatory effects and causes less g astric irritation. \200 The therapeutic dose range of paracetamol in children and adults is 10 \200\22315 mg/kg. In severe symptoms maximum single dose is 20 mg/kg. Adults and chil dren who are small for age should be weighed and the dose calculated. In most patients the dose can safely be based on age. The adult dose is 0.5 \200\2231g 4 \200\2236 hourly (maximum 4g in 24 hours). \200 For ch ildren aged less than 6 years use paracetamol infant suspension (120 mg/5 mL). \200 2 \200\2233 months (babies with weight > 4 kg, born after 37 weeks): 2.5 mL (60 mg). If necessary a second 2.5 mL dose may be given after 4 \200\2236 hours. Do not give more than two doses in 24 hours. \200 3 \200\2236 months: 2.5 mL (60 mg) \200 6 \200\22324 months: 5 mL (120 mg) \200 2 \200\2234 years: 7.5 mL (180 mg) \200 4 \200 \2236 years: 10 mL (240 mg). For children aged 6 years and over use paracetamol six plus suspension (250 mg/5 mL): \200 6 \200\2238 years: 5 mL (250 mg) \200 8 \200\22310 years: 7.5 mL (3 75 mg) \200 10 \200\22312 years: 10 mL (500 mg). Paracetamol may be repeated 4 \200\2236 hourly. Adults, and children older than 3 months, may have a maximum of four doses in 24 hours. Overdosage can cause liver and renal damage ( b p.190). Compound analgesics (paracetamol + opioid) Compound analgesic tablets containing paracetamo l and low doses of opioids are widely used, but have little bene \201 t over paracetamol a lone and cause more side effects, such as constipation and dizziness, particularly in elder ly people. These compound preparations include: \200 Co-codamol 8/500 (codeine phosphate 8mg, paracetamol 500mg). \200 Co-dydramol (dihydrocodeine tartrate 10mg, paracetamol 500m g). Compound preparations of paracetamol and full doses of opioids, eg co-codamol 30/500 (c odeine phosphate 30mg, paracetamol 500mg), are more potent than paracetamol alone, but may cause opioid side effects, including nausea, vomiting, constipation, dizziness, drowsiness and respiratory depression. Opioid dependency can occur with prolonged usage. 275 ANALGESICS: NSAIDs Analgesics: NSAIDs Non-steroidal anti-in \202 ammatory drugs NSAIDs are often used to trea t musculoskeletal pain, with or without in \202 ammation, although in many cases non-drug treatment (heat or cold, elevation) and paracetamol should be tried \201 rst. NSAIDs can cause gastric irritation, diarrhea, GI bleeding and perforation, with i risk at higher drug dosage and in patients aged > 60 years and those with a history of peptic ulcer. NSAIDs ma y exacerbate asthma and can precipitate renal failure in patients with heart failure, cirrh osis or renal insuf \201 ciency. Interactions occur with diuretics, warfarin, lithium and other drugs (see BNF ). When possible, advise that NSAIDs be taken after food to d risk of GI side effects. If NSAID treatment is essential in patients at high risk of GI prob- lems consider prophylactic treatment with misoprostol (see BNF ). Many NSAIDs are available and all can cause serious adverse effects, but ibuprofen, diclofe nac and naproxen are relatively safe and cover most requirements. Ibuprofen has the lowest incidence of side effects, is the cheapest of these drugs and may be bought without prescri ption. Ibuprofen is useful in children as an analgesic and antipyretic, especially when par acetamol is insuf \201 cient. \200 Ibuprofen dosage 1.2 \200\2231.8g daily in 3 \200\223 4 divided doses (max 2.4g daily). Child ( > 7kg): 20mg/kg daily in 3 \200\2234 divided doses. Diclofenac (oral or rectal) 75 \200\223150mg daily in 2 \200\2233 divided doses. \200 Nap roxen 500mg initially, then 250mg 6 \200\2238-hourly (max 1.25g daily). Acute gout 750mg initially, then 250mg 8-hourly until pain resolves. Injectable NSAIDs Some NSAIDs may be given by injection for musculoskeletal pain (eg acute low back pain), or for renal or biliary colic. The contra indications and side effects are the same as for oral treatment. Intramuscular (IM) injections are painful and can cause ste rile abscesses, so oral or rectal treatment is preferable. NSAIDs provide effective analges ia for renal colic, but the onset is slower than with IV opioids, which some prefer. A NSAI D is particularly useful in suspected drug addicts who claim to have renal colic. \200 Ke torolac may be given IM or slowly IV (initial dose 10mg over at least 15sec: see BNF ). It is useful as an adjunct for MUAs. Diclofenac must be given by deep IM injection (not IV, which causes venous thrombosis). Dos e: 75mg, repeated if necessary after 30min (max 150mg in 24 hours). Topical NSAIDs NSAID gels or creams applied to painful areas provide some analgesia, but ar e less effective than oral treatment. Systemic absorption may occur and cause adverse effec ts as for oral NSAIDs. 276 CHAPTER 7 Analgesia and anesthesia Analgesics: opioids Morphine Morphine is the standard analgesic for severe pain. As well as providing analgesia, it is sometimes used for cardiogenic pulmonary oedema ( b p.101) to r elieve distress and to help increase venous capacitance. Morphine often causes nausea and vomiting in adults, so consider giving an anti-emetic (cyc lizine 50mg IV/IM or prochlorperazine 12.5mg IM). Anti- emetics are not usually necessary i n children aged < 10years. Other side-effects of opioids include drowsiness and constipation. Respiratory depression a nd hypotension may occur, especially with large doses. Pinpoint pupils can complicate neuro logical assessment. Naloxone ( b p.188) reverses the effects of opioids. In acute condition s, give morphine by slow IV injection, which provides rapid but controlled analgesia. The d ose varies with the patient and the degree of pain. Titrate the dose depending on the respo nse: 2mg may be adequate in a frail old lady, but sometimes > 20mg is needed in a young \201 t person with severe injuries. Dilute morphine with 0.9 % saline to 1mg/mL (label the syringe clearly) and give it slowly IV (1 \200\2232mg/min in adults) in 1mg increments unti l pain is relieved. Give further analgesia if pain recurs. IV morphine dose in children is 100 \200\223200micrograms/kg, given in increments, repeated as necessary. Patient-controlle d analgesia using a computerized syringe pump is very good for post-operative analgesia, bu t rarely appro- priate in the ED. IM injections provide slower and less controlled effects than IV analgesia: avoid their use , especially in shocked patients. IM morphine could be used in children needing strong anal gesia but not IV \202 uids (eg while dressing super \201 cial burns), but oral or nasal analgesia is preferable. \200 Morphine may be given orally as Oramorph oral solution: child aged 1 \200\2235 years: max dose 5mg (2.5mL); \200 child aged 6 \200\22312 years: m ax dose 5 \200\22310mg (2.5 \200\2235mL). Codeine is given orally for moderate pain (30 \200\22360mg 4hrly, max 240mg daily) and has side effects similar to morphine. Codeine may also be given IM (but not IV, because it may cause hypotension). Dihydrocodeine is very similar to codeine. \200 Diamorphine (heroin) has similar effects to morphine, but is more soluble and so can be dissolved in a very small volume of diluent. Nasal diamor- phine provides effective analgesia in children ( b p.281). Fentanyl is a short-acting opioid which is often used in anesthesia. \200 Pethidine provi des rapid but brief analgesia, but is less potent than mor- phine. It is sometimes used for renal or biliary colic in preference to morphine, which occasionally causes smooth muscle spasm ( b p.277). Pethidine is given slowly IV, titrated as necessary (usual adult dose 50m g IV), or less effectively IM (50 \200\223100mg). Give an anti-emetic with it. 277 ANALGESICS: OPIOIDS Smooth muscle spasm due to opioid analgesics In a few patients opioids such as morphine can cause severe pain due to smooth muscle spasm, especially spasm of the sphincter of Oddi. A bout 5 \200\22320 minutes after morphine has been given, severe colicky abdominal pain deve lops. This may be typical of biliary colic but can mimic renal colic, intestinal perforatio n or myocardial infarction. Pain from spasm of the sphincter of Oddi may be relieved by glucagon (1mg IV, repeated if n ecessary) although this is liable to cause vomiting. Naloxone (0.2mg IV, repeated if necess ary) is also effective, but may reverse desired analgesia. GTN can also relieve smooth musc le spasm of the sphincter of Oddi. Glucagon is probably the treatment of choice for this ra re complication of opioid analgesia. 278 CHAPTER 7 Analgesia and anesthesia Analgesics: Entonox and ketamine Entonox Entonox is a mixture of 50 % N 2 O and 50 % O 2 . It is stored as a compressed gas in blue cylinders with a blue and white shoulder. It is unsuitable for use at < \200\2236 C, since the gasses separate and a hypoxic mixt ure could be given. Entonox diffuses more rapidly than nitrogen and so is contra indicat ed with the following: undrained pneumothorax (since it may produce a tension pneumothorax) , after diving ( i risk of decompression sickness), facial injury, base of skull fracture, intestinal obstruction, d conscious level. Entonox is controlled by a demand valve and i nhaled through a mask or mouthpiece, often held by the patient. It gives rapid and effectiv e analgesia and is widely used in prehospital care. In the ED, Entonox is useful for ini tial analgesia, eg while splinting limb injuries, and for many minor proce- dures, such as reduction of a dislocated patella or \201 nger. Tell the patient to breathe deeply throug h the mask or mouthpiece, and warn that he may feel drowsy or drunk, but that this will wea r off within a few minutes. Ketamine Ketamine is a dissociative anesthetic drug which may be given IM or IV by experts, and which provides strong analgesia in sub-anesthetic dosage. It is rarely used in hospita l practice for adults, because it may cause severe hallucinations, but these are less of a problem in children. It is very useful for sedation of children for procedures such as sutu ring of minor wounds. Ketamine is particularly useful in prehospital care and is the most a ppro- priate drug in the rare cases when a GA is needed outside hospital for extrication or emergency amputation.