R on T phenomenon.  Arises when the R wave of a ventricular ectopic beat falls on the T wave of the preceding beat. At the middle of the T wave, the myocardium is partly depolarised and partly repolarised, and thus vulnerable to establishment of re-entrant and circulatory conduction, leading to VF or VT.

R wave.  First upward deflection of the QRS complex of the ECG (see Fig. 59b; Electrocardiography). Tends to increase in size from V₁ to V₆, with an accompanying reduction in size of S wave across these leads. Loss of this ‘R wave progression’, with a sudden increase in R wave size in V₅ or V₆, may indicate old anterior MI. In V_1–6, at least one normally exceeds 8 mm, but none exceeds 27 mm.

Rabeprazole sodium.  Proton pump inhibitor; actions and effects are similar to those of omeprazole.

Rabies.  Infection caused by a lyssavirus of the rhabdovirus family, eradicated from Britain in 1902; however, occasional cases thought to have originated outside the UK have occurred in animals, e.g. dogs and bats. Fewer than 5 cases occur annually in Europe and the USA. Spread mainly via domestic dogs and cats, but also by foxes, bats and other wildlife. Transmitted via infected saliva penetrating broken skin or intact mucosa; the virus replicates in local muscle then migrates proximally along peripheral nerves to dorsal root ganglia and the CNS, eventually causing lethal encephalitis. Incubation period is usually 20–90 days in humans, but may be 4 days to several years.

Malaise, fever, depression and psychosis may be followed by laryngeal spasm, and extreme anxiety on drinking fluids. Respiratory and autonomic failure occurs early and cardiac involvement, including myocarditis, is common.

Treatment of established rabies includes injection of human anti-rabies immunoglobulin, early IPPV, sedation and paralysis, with careful maintenance of acid–base and fluid balance. Almost inevitably fatal once established (death typically occurs 2–10 days after symptoms appear), it may be prevented by wound cleaning and active and passive immunisation.

Warell MJ (2008). Curr Opin Infect Dis; 21: 251–7

Radford nomogram.  Diagram showing the relationship between tidal volume, patient’s weight and respiratory frequency. Used to aid appropriate selection of ventilator settings for children and adults. Now rarely used.

[Edward P Radford (1922–2001), US physiologist]

Radial artery.  Terminal branch of the brachial artery. Arises in the antecubital fossa, level with the radial neck, and runs distally on the tendons and muscles attached to the radius (biceps tendon, supinator, pronator teres, flexor digitorum superficialis, flexor pollicis longus, pronator quadratus). Lies deep to brachioradialis muscle in the upper forearm, but subcutaneous in the lower forearm and easily palpable, especially over the distal quarter of the radius. Runs deep to abductor pollicis longus and extensor pollicis brevis tendons at the radial styloid, entering the anatomical snuffbox. Then enters the palm between the first and second metacarpals, forming the deep palmar arch. Branches include a superficial palmar branch (enters the palm superficial to the flexor retinaculum), which supplies the muscles of the thenar eminence before anastomosing with the superficial palmar arch. At the wrist, it is a common site for palpation of the pulse and for arterial cannulation.

See also, Ulnar artery

Radial nerve (C5–T1).  Terminal branch of the posterior cord of the brachial plexus. Descends in the posterior upper arm, passing laterally behind the middle of the humerus in the radial groove. Crosses the antecubital fossa anterior to the elbow joint, between brachialis and brachioradialis. Descends under brachioradialis lateral to the radial artery in the forearm, passing posteriorly proximal to the wrist to end on the dorsum of the hand as digital branches.

May be blocked at the elbow, wrist, and at mid-humerus with the elbow flexed (the nerve is palpable in the radial groove).

See also, Brachial plexus block; Elbow, nerve blocks; Wrist, nerve blocks

Radiation.  Emission of energy in the form of waves or particles. Includes emission of electromagnetic waves (e.g. light), most of which is non-ionising (does not have sufficient energy to overcome electron binding energy). Ionising radiation may result in displacement of electrons in organic material with the potential for tissue damage, and includes:

Exposure to ionising radiation is kept to a minimum with appropriate storage and handling of radioisotopes, minimal use of X-rays and appropriate use of shielding. Formal training is required for those performing or directing radiology procedures.

See also, Environmental safety of anaesthetists

Radiography in intensive care.  Increasingly used as the range and quality of techniques and equipment available increase. Consultation with radiologists aids the proper selection and interpretation of many imaging techniques. In most cases, the use of mobile equipment results in less than optimal results but may be acceptable given the difficulty of transporting critically ill patients from the ICU; subtle changes between sequential films may be misleading if this is not taken into account. Investigations include CXR, ultrasound and CT and MRI scanning; bedside CT scanners are now available but MRI requires transport to the imaging department. Radioisotope scanning usually requires transfer from the ICU.

Practical considerations include the requirement for sedation and adequate monitoring during transport or the procedure itself, the interference of the procedure with background therapy including the requirement for moving the patient (e.g. to place films underneath), and the potentially adverse effects of radiological contrast media.

See also, Imaging in intensive care

Radioisotope scanning.  Use of radioisotopes to label certain parts of the body in order to investigate organ function, either directly or attached to circulating cells. Includes the following:

The radiation contained within the body after scanning is negligible, posing no risk to staff.

Radioisotopes.  Isotopes of elements that undergo disintegration; i.e. the nucleus emits α, β or γ radiation either spontaneously or following a collision. Used clinically as labels to determine fluid compartments, blood flow, pulmonary distribution and sites of infection. Technetium-99 m and xenon-133 are often suitable because they are easy to use and their half-lives are short. Also used to label metabolically active substances which are taken up by certain tissues, allowing imaging of the tissue concerned, e.g. fibrinogen labelled with iodine-123 accumulates in a clot and may be used to detect DVT. Therapeutic use includes radiotherapy.

See also, Radioisotope scanning

Radiological contrast media.  Contain large molecules that absorb X-rays (e.g. barium [enteral] or iodine [enteral or iv]) or have paramagnetic properties (e.g. gadolinium) for MRI scanning. Adverse reactions may follow iv injection:

Thus initial hypertension may be followed by prolonged hypotension. Renal failure may result from cardiovascular changes plus direct toxicity.

Incidence of reactions and renal failure is decreased by using low osmolar, non-ionic media. Other measures to prevent renal injury include adequate hydration and administration of N-acetylcysteine. Resuscitation equipment and drugs must always be available.

Dickinson MC, Kam PCA (2008). Anaesthesia; 63: 626–34

See also, Adverse drug reactions

Radiology, anaesthesia for.  Most radiological procedures require neither general anaesthesia nor sedation. Anaesthesia may be required for the very young, confused or agitated patients and those with movement disorders. Procedures include CT scanning, MRI, angiography and invasive procedures, e.g. embolisation of vascular lesions in neuroradiology.

Preoperative assessment and preparation should be as for any anaesthetic procedure.

Radiotherapy.  Use of ionising radiation to treat neoplasms. May involve:

Techniques used include sedation or general anaesthesia using TIVA with propofol, or intermittent boluses of ketamine (especially in children).

Patients formerly treated by radiotherapy may have inflammatory or fibrotic changes in the irradiated area. Pulmonary, cardiac, neuroendocrine, renal and hepatic involvement may be present. Tissue fibrosis around the airway may make tracheal intubation difficult.

McFadyen JG, Pelly N, Orr RJ (2011). Curr Opin Anaesthesiol; 24: 433–8

Randomisation.  Technique for allocating subjects (e.g. patients to treatment groups in clinical trials) that reduces allocation bias when samples are compared. Ensures that factors such as age, sex and weight are randomly distributed amongst the groups; i.e. any difference in these factors is due to chance alone.

Computer-generated random numbers are usually employed. Use of coins or dice is tedious and presents the temptation to repeat an allocation if the result is not liked. Other methods have also been used, e.g. allocation of alternate patients, or according to patients’ birthdays or record numbers. However, these methods cannot always be guaranteed free of hidden bias.

Ranitidine hydrochloride.  H₂ receptor antagonist; better absorbed and more potent than cimetidine, with fewer side effects. Does not inhibit hepatic enzymes or interfere with metabolism of other drugs. Oral bioavailability is about 50%. Plasma levels peak within 15 min of im injection and 2–3 h after oral administration; effect lasts about 8 h. Half-life is about 2 h. Undergoes hepatic metabolism and is excreted via urine, hence the dose is reduced in renal failure.

Ranking,  see Statistical tests

Raoult’s law.  The addition of a solute to an ideal solution reduces the vapour pressure of the solvent in proportion to the molar concentration of the solute.

[François M Raoult (1830–1901), French scientist]

See also, Colligative properties of solutions

RAP.  Right atrial pressure, see Cardiac catheterisation; Central venous pressure

Rapacuronium bromide.  Non-depolarising neuromuscular blocking drug, introduced in the USA in 1999 and withdrawn in 2001 just before its introduction in the UK, because of reports of fatal bronchospasm. Chemically related to vecuronium, it causes rapid onset of neuromuscular blockade (tracheal intubation possible within 60 s) with fast recovery (6–30 min depending on dosage) and was thus suggested as an alternative to suxamethonium.

Rapid opioid detoxification.  Technique for treating opioid addiction by precipitating withdrawal using opioid receptor antagonists, e.g. naloxone or naltrexone, supposedly reducing relapse rates compared with conventional management. Ultra-rapid opioid detoxification refers to administration of general anaesthesia or heavy sedation for prolonged periods to reduce awareness or recall of unpleasant withdrawal symptoms whilst the opioid antagonists are given. The technique is controversial (especially the ultra-rapid form) since deaths have occurred and supportive evidence for its efficacy is poor.

Singh J, Basu D (2004). J Postgrad Med; 50: 227–32

Rapid sequence induction,  see Induction, rapid sequence

Rate–pressure product (RPP).  Product of heart rate and systolic BP, used as an indicator of myocardial workload and O₂ consumption. It has been suggested that RPP should be maintained below 15 000 in patients with ischaemic heart disease during anaesthesia. Its usefulness has been questioned, since a proportional increase in rate may increase myocardial O₂ demand more than the same increase in BP. A pressure–rate quotient (MAP/rate) of < 1 has been suggested as being a better predictor of myocardial ischaemia.

RBBB.  Right bundle branch block, see Bundle branch block

RDS,  see Respiratory distress syndrome

Reactance.  Portion of impedance to flow of an alternating current not due to resistance; e.g. due to capacitance or inductance. Given the symbol X, and measured in ohms.

[Georg S Ohm (1787–1854), German physicist]

Rebreathing techniques,  see Carbon dioxide measurement

Receiver operating characteristic (ROC) curves.  Curves drawn to indicate the usefulness of a predictive test, originally derived from analysis of radar signals between the World Wars (i.e. did a deflection represent a real signal or just random noise; and if the former, with what degree of certainty?). For the test to be analysed (e.g. the usefulness of ASA physical status to predict mortality after anaesthesia), each cut-off level is examined in turn, and sensitivity and specificity calculated for it. Thus, for example, an ASA grade of 1 has high sensitivity (all deaths have an ASA grade of 1 or above) but low specificity (most patients with a grade of 1 or above do not die). For an ASA grade of 2, sensitivity is a little lower (some patients who die have a grade of 1, and will not be predicted by a grade of 2) whilst specificity is higher, although still poor (a grade of 2 is better at predicting death than a grade of 1, although most patients achieving 2 or above still do not die). The process continues until grade 5, which has low sensitivity (few of the deaths have a grade of 5) but high specificity (most patients who are graded 5 do, by definition, die). Sensitivity is plotted against (1 – specificity) and a curve obtained (Fig. 133); the area under the curve (AUC) represents the usefulness of the test: a perfect test includes 100% of the available area and one where prediction is no better than chance, 50%.

ROC curves may be drawn using continuous (e.g. C-reactive protein to predict infection), ordinal (e.g. ASA system) or nominal (e.g. presence of different features on the ECG to diagnose MI) scales. They may also be drawn for different tests in the same plot, allowing comparison between the tests. They also allow selection of the best cut-off to use clinically, usually the uppermost and most left-hand part of the curve, being the best compromise between sensitivity and specificity. They are increasingly used to analyse the usefulness of tests or scoring systems in anaesthesia and intensive care, including difficult tracheal intubation and other outcomes.

Galley HF (2004). Br J Anaesth; 93: 623–6

Receptor theory.  States that receptors are specific proteins or lipoproteins located on cell membranes or within cells that interact selectively with extracellular compounds (agonists) to initiate biochemical events within cells. The structures of the agonist and receptor determine the selectivity and quantitative response. Drugs that interact with the receptor and inhibit the effect of an agonist are antagonists. Degree of binding to receptors is affinity; ability to produce a response is intrinsic activity.

Initial assumptions that the degree of response is proportional to the number of receptors occupied are not universally accepted. Other suggestions include:

Interaction of drug and receptor may resemble Michaelis–Menten kinetics. Covalent, ionic and hydrogen bonding, and van der Waals forces may be involved.

Expression of receptors varies. Chronic stimulation (e.g. asthmatics taking β₂-adrenergic receptor agonists) results in a decreased number of receptors (downregulation) whereas understimulation (e.g. following spinal cord injury) leads to an increased number of receptors (upregulation).

See also, Dose–response curves; Pharmacodynamics

Recommended International Non-proprietary Names (rINNs),  see Explanatory Notes at the beginning of this book

Record-keeping.  The first anaesthetic chart was devised by Codman and Cushing in 1894 at the Massachusetts General Hospital, for recording of respiration and pulse rate. BP charting was included in 1901 at Cushing’s insistence. F_IO₂ was included by McKesson in 1911.

Careful record-keeping is now recognised as essential to chart preoperative risk factors, the perioperative course of anaesthesia and postoperative events/instructions. It is particularly useful when taking over another anaesthetist’s anaesthetic, and for providing information to those administering anaesthesia subsequently. Similarly, ICU records should chart physiological data, therapy and instructions relating to the stay of any patient in an ICU. Record-keeping is also important for teaching, research and audit, and is extremely important in medicolegal aspects of anaesthesia. Although tending to include similar information, anaesthetic and intensive care charts are not standardised nationally, although this has been suggested.

Automated anaesthetic record systems are increasingly used, sometimes incorporated into anaesthetic machines or ICU monitoring systems. They provide accurate, legible and complete documents for data acquisition and subsequent scrutiny. Data from monitoring devices are incorporated with information provided by the anaesthetist/intensive care staff (e.g. drug or other interventions), although lack of familiarity with keyboards or computers may be a hindrance.

Postoperative recovery and progress may be recorded on separate charts, or on the anaesthetic chart.

[Ernest A Codman (1869–1940), US surgeon]

Recovery from anaesthesia.  Period from the end of surgery to when the patient is alert and physiologically stable. Definition is difficult because some drowsiness may persist for many hours. Recovery testing is used for more precise investigation. Time to recovery depends on the patient’s condition, drugs given, their doses, and the patient’s ability to eliminate them. For inhalational anaesthetic agents, similar considerations as for uptake are involved, plus length of operation and degree of redistribution to fat. Thus blood gas solubility is the most important factor initially, but more potent agents (e.g. isoflurane) are more extensively bound to fat after prolonged anaesthesia than less potent ones, e.g. desflurane. For iv anaesthetic agents, initial recovery is due to drug redistribution from vessel-rich to vessel-intermediate tissues; subsequent course is related to the rate of clearance from the body. Thus propofol characteristically results in rapid clear-headed emergence, whereas thiopental is more likely to produce drowsiness lasting several hours, especially after repeated dosage. Recommendations for provision of recovery care (Association of Anaesthetists):

The speed and quality of recovery from anaesthesia have been proposed as a possible measure of quality of anaesthesia.

See also, Anaesthetic morbidity and mortality

Recovery position.  Position recommended for unconscious but spontaneously breathing subjects, assuming no contraindication, e.g. cervical spine injury. Encourages a clear airway and drainage of vomitus, secretions and blood away from the airway. Often used during recovery from anaesthesia.

Any recovery position is a compromise between the full prone position (better airway and drainage but more diaphragmatic splinting) and the full lateral position (less diaphragmatic splinting but less effective for the airway and less stable; also may be harmful in neck injury). Classically includes flexion of both arms with the upper hand placed under the jaw to support the airway (Fig. 134). The actual position adopted should reflect the particular circumstances of the case and the need to protect the airway, stabilise the neck and allow unhindered ventilation. It should be possible to observe the patient at all times and to turn him/her supine easily when required.

Recovery room.  An area reserved for postoperative care was described by Florence Nightingale in 1863, but the first dedicated recovery room was opened in the USA in 1923. Many more were introduced there after experiences in World War II and the Korean War. First introduced in the UK in 1955.

[Florence Nightingale (1820–1910), English nurse]

See also, Recovery

Recovery testing.  Ranges from simple clinical assessment to more sophisticated methods, e.g. used for experimental comparison between anaesthetic techniques and drugs. Routine testing is usually limited to assessment of general alertness and orientation, and ability to respond, drink, dress and walk where appropriate (e.g. day-case surgery).

Problems of detailed recovery testing are related to the time taken, cumbersome equipment required, fatigue, boredom and learning if tests are repeated. Critical flicker–fusion, reaction testing, letter deletion and memory tests are most widely used and thought to be reasonably efficient, the first two especially so. General advice to patients is usually to avoid potentially dangerous activities (e.g. driving, cooking, using machinery) for 24 h following day-case anaesthesia, although subtle changes may persist beyond this period; 48 h has been suggested.

Rectal administration of anaesthetic agents.  Results in effective absorption of drugs because of a rich blood supply provided by communicating plexuses formed by the superior, middle and inferior rectal arteries and veins. Drugs undergo minimal first-pass metabolism, because the plexuses are anastomoses between portal and systemic circulations. The technique is usually restricted to children. Traditionally used more in continental Europe, e.g. France. Drugs used have included diazepam 0.4–0.5 mg/kg (widely used for treatment of convulsions in children), methohexital 15–25 mg/kg and thiopental 40–50 mg/kg as 5–10% solutions. Opioids and ketamine have also been given in this way. Diethyl ether was administered rectally by Pirogoff. Bromethol and paraldehyde were used in the 1920s to produce unconsciousness (basal narcosis).

Rectus sheath block.  Performed as part of abdominal field block or alone to reduce pain from abdominal incisions. Abdominal contents are not anaesthetised.

With the patient supine, a blunted needle is introduced 3–6 cm above and lateral to the umbilicus. A gentle ‘scratching’ motion may aid identification of the tough anterior layer of the sheath, puncture of which is accompanied by a click. The needle is advanced up to the resistance offered by the posterior layer of the sheath, and 15–20 ml local anaesthetic agent injected after negative aspiration. Deposition of solution between rectus muscle and posterior layer allows spread up and down, blocking the lower 5–6 intercostal nerves within the sheath. Spread between the muscle and anterior layer is limited by the tendinous intersections along its length. Multiple injections have been suggested between intersections, to improve spread, but the posterior layer is deficient below a point halfway between the umbilicus and pubis, and peritoneal puncture is more likely below this level.

Recurarisation.  Recurrence of non-depolarising neuromuscular blockade after apparent reversal with acetylcholinesterase inhibitors. Originally described with tubocurarine in patients with impaired renal function, where the duration of action of the neuromuscular blocking drug exceeds that of the acetylcholinesterase inhibitor. Has been described with other neuromuscular blocking drugs.

Red cell concentrates,  see Blood products

Reducing valve,  see Pressure regulators

Refeeding syndrome.  Clinical syndrome seen after reintroduction of nutrition to previously starved patients, often seen on ICU. First noted after World War II, when malnourished prisoners of war inexplicably died of cardiac failure after receiving a normal diet. Associated with any condition leading to malnutrition (e.g. anorexia nervosa, alcoholism, intra-abdominal sepsis).

Byrnes MC, Stangenes J (2011). Curr Opin Clin Nutr Metab Care; 14:186–92

Referred pain.  Pain felt in a somatic site remote to the source of pain, usually visceral; e.g. diaphragmatic pain is felt in the shoulder tip. The aetiology is obscure, but is thought to be related to the embryological segment from which the organ arose, e.g. diaphragm from the neck region, and heart from the same region as the arm.

Effects of local anaesthetic injected at referred areas are inconsistent, supporting both theories (should ease the pain if facilitation is responsible, but not if convergence is responsible).

Reflex arc.  Involves predictable, repetitive stereotypic responses to a particular sensory stimulus. Consists of sense organ, afferent neurone, one or more synapses, efferent neurone and effector. The afferent neurones enter the spinal cord via dorsal roots or brain via cranial nerves; the efferent neurones leave via ventral nerve roots or corresponding motor cranial nerves. Also involved in autonomic functions. The simplest reflex arc is monosynaptic, e.g. knee jerk and other stretch reflexes involving muscle spindles. Polysynaptic reflex arcs (two or more synapses) include the withdrawal reflex. Widespread effects may result from activation of a single reflex arc because of ascending, descending, excitatory and inhibitory interneurones.

Reflex sympathetic dystrophy,  see Complex regional pain syndrome

Reflux,  see Gastro-oesophageal reflux

Refractometer,  see Interferometer

Refractory period.  Period during and following the action potential during which the neurone is insensitive to further stimulation. Subdivided thus:

Refrigeration anaesthesia.  Use of cold to reduce pain sensation. Used by Larrey in 1807, although the effect of cold on pain has been recognised for centuries. Up to 3 h packing in ice was recommended for operations through the thigh. The principle is still used today, e.g. ethyl chloride spray.

Regional anaesthesia.  Term originally coined by Cushing to describe techniques of abolishing pain using local anaesthetic agents as opposed to general anaesthesia. Pioneers included Halstead, Corning and Labat in the USA and Bier, Braun and Lawen in Europe.

See also, specific blocks; Nerve injury during anaesthesia

Regional tissue oxygenation.  Important because shock and hypoxaemia cause redistribution of blood flow and alter the metabolic properties of cells; global measurements thus fail to detect areas of local ischaemia. Measurement of regional tissue oxygenation may be useful in critically ill patients because deficiencies may be involved in the development and continuation of MODS. Lack of evidence of benefit and technical difficulties have hindered the more intricate techniques from becoming routine practice. Methods of assessment include:

Dyson A, Singer M (2011). Curr Opin Crit Care; 17: 281–9

Regression,  see Statistical tests

Regurgitation.  Term usually describing passive passage of gastric contents into the pharynx. Silent, thus aspiration of gastric contents may occur unnoticed. Normally prevented by the lower oesophageal sphincter; however, swallowed dyes have been found to stain areas of the pharynx and larynx during/after anaesthesia in normal patients.

Relative analgesia.  Technique used in dental surgery involving nasal administration of subanaesthetic concentrations of N₂O, e.g. 10% in O₂, slowly increased to 30–50%. Verbal contact is maintained at all times, and the concentration of N₂O reduced if excessive drowsiness occurs. Performed by the dentist, it depends partly on suggestion.

Relative risk reduction.  Indicator of treatment effect in clinical trials. For a reduction in incidence of events from a% to b%, it equals ( [a − b] ÷ a)%. Gives an overestimated impression of treatment effect if events are rare, and an underestimate if events are common.

See also, Absolute risk reduction; Meta-analysis; Number needed to treat; Odds ratio

Relatives of critically ill patients.  Present particular challenges to ICU staff because of the serious nature of the patient’s condition, unfamiliarity with the ICU environment and the natural behavioural responses to extreme stress, including fear, anger and guilt. The suddenness of many severe conditions may exacerbate relatives’ distress. Relatives must be kept informed about the patient’s progress, preferably by a consistent single senior doctor accompanied by a member of the nursing staff; they should also feel included in discussions about treatment (including its withdrawal).

Honest and clear explanations, using lay language, may need repeating several times and the potential frustration felt by the medical team must not be transmitted to the relatives. Most ICUs have a separate room for interviews with patients’ families and friends, which is preferable to the open ward or corridor. In general, few restrictions are placed on visiting times, and most relatives appreciate and respect the need for staff to perform basic care and procedures during which they may be asked to leave the unit. However, some may choose to stay and participate in some aspects of their relative’s care, e.g. washing or shaving. Counselling and religious support may be required and is often best arranged via the ICU staff.

Whether relatives should witness attempts at resuscitation (e.g. in casualty departments) has attracted recent debate, with some welcoming the opportunity for relatives to see that appropriate attempts to save the patient are being made, whilst others argue that their presence may be stressful for medical and nursing staff.

Curtis JR, White DB (2008). Chest; 134: 835–43

Remifentanil.  Ultra-short-acting synthetic opioid analgesic drug, 2000 times more potent than morphine, introduced in the UK in 1997. Available as a white powder for reconstitution to a 0.1% solution which is stable for 24 h at room temperature. Further diluted for administration; in adults a 50 µg/ml solution is recommended by the manufacturer. Approximately 70% protein-bound. Rapidly metabolised by non-specific plasma and tissue esterases to remifentanil acid (very low potency) and excreted renally. Its context-sensitive half-life is about 3 min regardless of the duration of infusion; thus provides a rapid recovery when stopped.

Because it is cleared so rapidly and completely, patients very soon experience pain postoperatively unless longer-acting analgesics are given before discontinuation. In addition, it has been suggested that the hyperalgesia that can occur following remifentanil infusions may be due to upregulation of NMDA receptors. Has been used via patient-controlled analgesia during labour (see Obstetric analgesia and anaesthesia). Not recommended for epidural or spinal use since the formulation contains glycine. Postoperative respiratory depression may occur if any drug is left in the dead space of iv lines and subsequently flushed with other drugs or fluids.

Remote ischaemic preconditioning,  see Ischaemic preconditioning

Renal blood flow (RBF).  Normally 1200 ml/min (400 ml/100 g/min); i.e. 22% of cardiac output.

RBF and GFR are reduced by most anaesthetic agents, mainly via reduced cardiac output and BP. Volatile agents are also thought to interfere with autoregulation, although some benefit may arise from the vasodilatation they cause, maintaining blood flow. Urine output therefore often falls perioperatively.

Other factors include pre-existing renal disease or conditions predisposing to renal failure or impairment, e.g. vascular surgery, toxic drugs, trauma, jaundice, hypovolaemia.

Renal failure.  Loss of renal function causing abnormalities in electrolyte, fluid and acid–base balance with increases in plasma urea and creatinine. Divided into acute and chronic renal failure.

Dennen P, Douglas IS, Anderson R (2010). Crit Care Med; 38: 261–75

Renal failure index,  see Renal failure

Renal transplantation.  First performed in 1950, and now widespread but limited mainly by the supply of kidneys. Cadaveric graft survival is up to 80–90% at 2 years. Previously considered an emergency and performed on unprepared patients, but the importance of proper preoperative assessment and preparation is now generally accepted. Dialysis is usually performed within 24 h before surgery.

Sarinkapoor H, Kaur R, Kaur H (2007). Acta Anaesthesiol Scand; 51: 1354–67

See also, Organ donation

Renal tubular acidosis.  Group of conditions characterised by decreased ability of each nephron to excrete hydrogen ions (cf. renal failure, where the overall number of functioning nephrons is reduced, but those that remain excrete more hydrogen ions than normal). Characterised by normal GFR, metabolic acidosis, hyperchloraemia and a normal anion gap. May be associated with distal tubule dysfunction (type 1), proximal tubule dysfunction (type 2; usually associated with other abnormalities of proximal tubule function, e.g. Fanconi’s syndrome), or aldosterone deficiency or resistance (type 4). Type 3 is now considered a combination of types 1 and 2 and not a separate entity. Acidosis may be severe, and accompanied by marked hypokalaemia (hyperkalaemia in type 4). Treatment includes alkali (e.g. oral sodium bicarbonate) in types 1 and 2, thiazides in type 2 and mineralocorticoid therapy in type 4.

[Guido Fanconi (1892–1979), Swiss paediatrician]

Reddy P (2011). Int J Clin Pract; 65: 350–60

Renin/angiotensin system.  Renin, a proteolytic enzyme (mw 37 kDa), is synthesised and secreted by the juxtacapillary apparatus of the renal tubule. Formed from two precursors, prorenin and preprorenin, its half-life is about 80 min. Secretion is increased in hypovolaemia, cardiac failure, cirrhosis and renal artery stenosis. Secretion is decreased by angiotensin II and vasopressin. Renin cleaves the circulating glycoprotein angiotensinogen with subsequent production of the peptides angiotensin I, II and III, involved in arterial BP control and fluid balance (Table 38). Angiotensin I is a precursor for angiotensin II, a powerful vasoconstrictor with a half-life of a few minutes. It causes aldosterone release from the adrenal cortex, and noradrenaline release from sympathetic nerve endings. It also stimulates thirst and release of vasopressin, and acts directly on renal tubules, resulting in sodium and water retention. Some may also be produced in the tissues. Angiotensin III also causes aldosterone release and some vasoconstriction.

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists are used to treat hypertension. Aliskiren, a direct renin inhibitor, has recently been introduced.

Angiotensin II or its analogues have been used as vasopressor drugs when α-agonists are unable to correct severe hypotension, e.g. during surgery for hepatic tumours secreting vasodilator substances.

Reperfusion injury.  Tissue injury resulting from restoration of blood flow after a period of ischaemia. Mechanisms include intracellular calcium excess, cellular oedema and free radicals. Although any tissue may be affected, most work has focused on cardiac function following hypoxic insult or hypoperfusion. Arrhythmias and myocardial stunning (reversible impairment of cardiac function) may also follow reperfusion.

See also, Isoprostanes, No reflow phenomenon

Reptilase time,  see Coagulation studies

Reserpine.  Antihypertensive drug, rarely used now because of its unfavourable side-effect profile. Depletes postganglionic adrenergic neurones of noradrenaline by irreversibly preventing its reuptake from axoplasm into storage vesicles. Crosses the blood–brain barrier and depletes central amine stores. Effects may last 1–2 weeks.

Side effects include bradycardia and postural hypotension, depression, sedation and extrapyramidal signs. No longer available in the UK.

Reservoir bag.  Usually 2 litre capacity in most adult anaesthetic breathing systems and 0.5–1.0 litre for paediatric use; its volume must exceed tidal volume. Movement indicates ventilation, but estimation of tidal volume from the degree of movement is inaccurate. Made of rubber (increasingly, latex-free), distending when under pressure; maximal pressure is thus prevented from rising above about 60 cmH₂O (Laplace’s law).

Residual volume (RV).  Volume of gas remaining in the lungs after maximal expiration. About 1.5 litres in the average 70 kg male; measured as for FRC. Increased RV accounts for most cases of increased FRC.

Resistance.  In electrical terms, the ratio of the potential difference across a conductor to the current flowing through it (Ohm’s law). Measured in ohms (Ω). Resistance to flow of a fluid through a circular tube is analogous to this; it equals the ratio of the pressure gradient along the tube to the flow through it.

Resistance vessels.  Term given to those blood vessels involved in regulation of SVR. 50% of resistance to blood flow is due to arterioles, which are thus the main regulators of SVR and therefore distribution of cardiac output.

Resonance.  Situation in which an oscillating system responds with maximal amplitude to an alternating external driving force. Occurs when the driving force frequency coincides with the natural oscillatory frequency (resonant frequency) of the system. May occur in pressure transducer systems if long, compliant tubing is used. May give rise to artefacts in the arterial waveform during direct arterial BP measurement.

Resonium,  see Polystyrene sulphonate resins

Respiration,  see Breathing …; Lung …; Metabolism

Respirators,  see Ventilators

Respiratory centres,  see Breathing, control of

Respiratory depression,  see Hypoventilation

Respiratory distress syndrome (RDS; Hyaline membrane disease).  Occurs in approximately 1% of all live births, almost exclusively in premature babies. Caused by deficiency of surfactant. Surfactant is normally detectable in the fetal lung at 24 weeks’ gestation, although reversal of amniotic fluid lecithin/sphingomyelin ratio (related to fetal lung maturity) only occurs at 30 weeks. Decreased lung compliance, increased work of breathing and alveolar collapse may lead to respiratory failure, with characteristic granular appearance of the CXR.

Treatment is directed towards preventing hypoxaemia with CPAP initially, although IPPV is usually necessary, whilst trying to avoid O₂ toxicity, barotrauma and retinopathy of prematurity. Exogenous surfactant given immediately after birth decreases mortality. Extracorporeal membrane oxygenation has been used.

Respiratory exchange ratio.  Estimation of respiratory quotient derived from expired CO₂/inspired O₂ measurements, thus dependent on ventilation.

Respiratory failure.  Defined as an arterial PO₂ < 8 kPa (60 mmHg) breathing air at sea level, and at rest, without intracardiac shunting.

Respiratory function tests,  see Lung function tests

Respiratory muscle fatigue.  Inability of the respiratory muscles to sustain tension with repeated activity. May be caused by:

Causes hypercapnic respiratory failure and difficulty in weaning from ventilators. Treatment is directed at the underlying cause.

Tobin MJ, Laghi F, Brochard L (2009). J Appl Physiol; 107: 962–70

Respiratory muscles.  Muscle actions during:

Respiratory quotient (RQ).  Ratio of the volume of CO₂ produced by tissues to the volume of O₂ consumed per unit time. At rest, it depends on the type of substrate being utilised: RQ of carbohydrate is 1, RQ of fat 0.7 and that of protein about 0.82. Also depends on the ratio of aerobic to anaerobic respiration that is occurring; after strenuous exercise RQ may rise transiently to up to 2 (due to excess lactic acid reacting with available bicarbonate).

Whole body RQ calculated by measurement of expired CO₂ and inspired O₂ only approximates to true RQ, since these volumes are affected by respiration. The term respiratory exchange ratio (R) is therefore becoming more commonly used for this measurement.

Respiratory sounds.  Traditionally assessed with a stethoscope, more recently analysed by digital processing using microphones or accelerometers placed on the chest wall. Sounds arise from vibration of airways and movement of fluid films within them. The nature of the sounds depends on the tissue through which they pass, e.g. quiet or absent in pleural effusion and pneumothorax, increased transmission in consolidation. The pitch is related to the size of the airway involved and the density of the gas.

Other sounds may occur (e.g. stridor), although not from the lung itself.

Gurung A, Scrafford CG, Tielsch JM, Levine OS, Checkley W (2011). Respir Med; 105: 1396–403

Respiratory stimulant drugs,  see Analeptic drugs; Opioid receptor antagonists

Respiratory symbols.  By convention, standardised thus:

e.g. F_IO₂ = inspired fractional concentration of O₂; P_aO₂ = arterial O₂ tension.

S_pO₂ has been suggested as representing haemoglobin saturation as measured by pulse oximetry.

Respirometer.  Device for measuring expiratory gas volumes. Examples:

[B Martin Wright (1912–2001), London engineer]

See also, Spirometer

Resuscitation,  see Cardiopulmonary resuscitation

Resuscitation Council (UK).  Multiprofessional group formed in 1981 to facilitate education of lay and professional members of the population in the most effective methods of resuscitation. Aims of the Council include: encouraging research and study of resuscitation techniques; the promotion of training and education in resuscitation; and the establishment and maintenance of standards. The Council has published guidelines for CPR and has set up a series of advanced courses in adult and paediatric resuscitation (i.e. ALS, ILS).

See also, European Resuscitation Council

Resuscitators,  see Self-inflating bags

Reteplase.  Recombinant plasminogen activator, used as a fibrinolytic drug in management of acute coronary syndromes. Has a longer half-life (13–16 min) than alteplase.

Reticular formation/activating system,  see Ascending reticular activating system

Retinopathy of prematurity (Retrolental fibroplasia).  Abnormal proliferation of retinal vessels in response to high arterial PO₂ for long periods. Very premature infants of low birth weight are the most susceptible, remaining so until 44 weeks’ postconceptual age. O₂ therapy should therefore be monitored closely. Precise mechanisms are unclear, as it may occur in infants who have not received additional O₂. Genetic factors appear to be important. The role of O₂ administered during anaesthesia is controversial, but F_IO₂ is generally thought to be best restricted to 0.3 unless higher concentrations are required to maintain arterial PO₂ of 8.5–11 kPa (60–80 mmHg).

Saugstad OD (2006). J Perinatol 26 (Suppl 1): S46–50

Retrobulbar block.  Performed to allow surgery to the globe of the eye, e.g. cataract extraction. Cranial nerves III and VI, and long and short ciliary nerves (branches of V₁) are blocked within the cone formed by the extraocular muscles. Now rarely used due to its relatively high frequency of complications, including retrobulbar haemorrhage, intravascular and subarachnoid injection and globe perforation. Peribulbar block and sub-Tenon’s block are safer and equally effective alternatives.

With the patient supine and looking straight ahead, a 3.0 cm needle is inserted through the conjunctiva at the lower lateral orbital rim. It is passed backward and 10° upward until its tip has passed the mid-globe, then angled medially and upward to reach a point behind the globe at the level of the iris. After aspiration, 2–4 ml lidocaine with hyaluronidase 5 U/ml is injected.

See also, Orbital cavity

Retrolental fibroplasia,  see Retinopathy of prematurity

Retzius cave block.  Used to supplement anaesthesia for prostatectomy and bladder surgery. The cave of Retzius is the space between the bladder and pubic symphysis, containing nerves of the sacral plexus and a venous plexus. After subcutaneous infiltration 2–3 cm above the pubis, an 8 cm needle is directed to the back of the symphysis. After negative aspiration for blood, 10 ml local anaesthetic agent with adrenaline is injected in the midline, with a further injection on each side.

[Anders Retzius (1796–1860), Swedish anatomist]

Reuben valve,  see Non-rebreathing valves

Revised trauma score (RTS).  Trauma scale derived from the trauma score but simplified and with greater emphasis on the presence of head injury. Uses the Glasgow coma scale, systolic BP and respiratory rate, each assigned a value of 0–4 according to deviation from normal, with 0 representing the most severe. The values are added to give a total RTS, with a normal of 12. Superior to the trauma score at predicting outcome; a RTS of < 4 suggests the need for transfer to a specialist trauma unit.

Gilpin DA, Nelson PG (1991). Injury; 22: 35–7

Reye’s syndrome.  Rare condition of unknown aetiology, characterised by vomiting, depression of consciousness and hepatic failure. Jaundice is typically absent or minimal. Usually occurs in children, typically following a viral illness; aspirin has been implicated in epidemiological studies and is thus contraindicated under 16 years of age. Thought to be due to an acquired mitochondrial abnormality. Treatment is mainly supportive, with correction of metabolic disturbances, cerebral oedema and raised ICP. Thought to be improved by administering up to a third of the fluid intake as 10% dextrose.

[R Douglas Reye (1912–1977), Australian pathologist]

Reynolds’ number (Re).  Dimensionless number predicting when flow of a fluid becomes turbulent:

Turbulent flow occurs at Re > 2000, laminar flow at < 2000.

[Osborne Reynolds (1842–1912), Irish-born English engineer]

Rhabdomyolysis,  see Myoglobinuria

Rhesus blood groups.  System of blood group antigens first described in 1939 following work on rhesus monkeys. Includes many antigens but the terms Rhesus (Rh)-positive and -negative usually refer to the D antigen, as it is the most immunogenic. Rh-negative individuals have no D antigen, and form anti-D antibodies when injected with Rh-positive blood. 85% of Caucasians are Rh-positive, 99% of Orientals.

Rheumatic fever.  Acute systemic autoimmune disease occurring after infection by certain serotypes of group A streptococci. Most common between 5 and 15 years of age; now rare in the West but still common in developing countries. Typically occurring 2–6 weeks after a sore throat, features include fever, flitting arthritis, carditis, chorea and erythema marginatum (erythema spreading out from a central macule whilst the centre returns to normal). Subcutaneous nodules (Aschoff bodies) may occur over the extensor surfaces of the wrists, elbows and knees. Epistaxis and abdominal pain are common.

Diagnosed clinically and by evidence of recent streptococcal infection. Traditionally treated with rest, penicillin, aspirin and corticosteroids, but the effect of drugs on valve disease is controversial. 50% of patients with carditis progress to valvular heart disease, which may not present until later in life. Mitral and aortic valves are most commonly affected.

Anaesthetic management of patients previously affected is directed towards any existing valve disease and associated complications (e.g. cardiac failure, pulmonary hypertension).

[Karl Albert Ludwig Aschoff (1866–1942), German pathologist]

Carapetis JR, McDonald M, Wilson NJ (2005). Lancet; 366: 155–68

See also, individual valve lesions

Rheumatoid arthritis (Rheumatoid disease).  Systemic inflammatory disease with many features of connective tissue diseases. Characterised by symmetrical polyarthropathy, but affects other organs too. Three times more common in females; peak incidence is at ages 30–50 years. Up to 5% of females over 60 years are affected in the UK. Aetiology is unclear but may involve an immunological process triggered by infectious agents coupled with a genetic predisposition. Recent advances in treatment, including early therapy with disease-modifying antirheumatic drugs (DMARDS), including biological agents which block tumour necrosis factor, appear to improve the course and severity of the condition.

[Augustus R Felty (1895–1963), US physician; Henrik SC Sjögren (1899–1986), Swedish ophthalmologist]

Samanta R, Shoukrey K, Griffiths R (2011). Anaesthesia; 66: 1146–59

See also, Intubation, difficult

Ribavirin (Tribavirin).  Antiviral drug; a nucleoside, it inhibits DNA synthesis and is active against many RNA and DNA viruses, although usually reserved for treatment of respiratory syncytial viral infection and Lassa fever. Also used in combination with interferon alfa for the treatment of chronic hepatitis C.

Rib fractures.  Middle ribs are most commonly affected. Fracture usually occurs at the posterior axillary line, the point of maximal stress. If the first three ribs are affected, injury to the aorta and tracheobronchial tree should be considered. If the lower ribs are involved, damage to liver, spleen and kidneys may occur. Pneumothorax and haemothorax may be present.

Rib fractures cause pain on breathing, with splinting of the chest wall, inability to cough and atelectasis. Multiple fractures may cause flail chest. The mainstay of treatment is good analgesia; this may involve systemic analgesics, epidural anaesthesia or intercostal nerve block.

General management is as for chest trauma and abdominal trauma.

Ribs.  Exist in 12 (thoracic) pairs, with occasional additional cervical or lumbar ribs. Attached to thoracic vertebrae posteriorly and costal cartilage anteriorly. Ribs 2–8 are typical (Fig. 135a), consisting of:

See also, Intercostal nerve block; Intercostal space

Rifabutin.  Antituberculous drug used for prophylaxis against Mycobacterium avium in immunocompromised patients.

Rifampicin.  Antibacterial drug, used primarily as an antituberculous drug but also in brucellosis, Legionnaires’ disease, severe staphylococcal infection, leprosy and as prophylaxis against meningococcal disease (thus may be given to ICU staff after caring for an infected patient or to household contacts). Causes hepatic enzyme induction and thus decreases the efficacy of oral contraceptives, anticoagulants and phenytoin.

RIFLE criteria  Consensus staging classification of acute kidney injury described in 2004, consisting of five stages of increasingly severe impairment graded according to plasma creatinine (Cr) level, GFR and/or urine output (UO):

Limitations of the classification include: frequent disparity between Cr and UO criteria; requirement for knowledge of baseline Cr/GFR; poor sensitivity of the ‘Risk’ criteria, i.e. less severe renal impairment is also associated with worse outcome.

A modified version, the AKIN (Acute Kidney Injury Network) classification, includes the following changes:

Borthwick E, Ferguson A (2010). Br Med J; 340: 85–91

Right atrial pressure,  see Cardiac catheterisation; Central venous pressure

Right ventricular function.  The right ventricle (RV) receives blood from systemic and coronary veins, and pumps it into the left ventricle (LV) across the pulmonary vascular bed. The pulmonary bed is of low resistance, therefore RV pressures (15–25/8–12 mmHg) are lower than systemic. The low intraventricular pressure permits right coronary blood flow to be continuous throughout the cardiac cycle. The output of the right heart is influenced by its preload, contractility and afterload.

The RV is very compliant and, when afterload increases (e.g. because of pulmonary vascular resistance secondary to lung injury), the RV dilates. The end-diastolic volume may increase to a greater extent than the preload; consequently, the RV ejection fraction will decrease markedly with increasing afterload. Changes in the geometry of the RV affect the function of the LV, and vice versa (ventricular interdependence), e.g. impaired RV function (whether acute or chronic) may hinder LV function via RV distension and deviation of the interventricular septum.

Although the RV is analogous to the LV in terms of control mechanisms, it is more difficult to assess; e.g. the relationship between RV preload, RV volume and RV filling pressures is not always constant. In addition, attempts to study RV function are hindered by the greater effect of respiratory excursions on the RV because the pressures involved are less than those on the left side of the heart.

RV function may be altered in acute respiratory failure, sepsis, chest trauma, ischaemic heart disease, and after cardiac surgery. The possibility of RV ischaemia or infarction in critically ill patients as a cause of RV dysfunction is increasingly recognised. During IPPV, decreased venous return subsequent to the increased intrathoracic pressure results in decreased RV end-diastolic volume and thus cardiac output. RV impairment may result in the classic features of right-sided cardiac failure, but may present as a general poor perfusion state.

Ringer’s solution.  Developed as an in vitro medium for tissues and organisms, emphasising the importance of inorganic ions in maintaining cellular integrity. Exact constitution varies between laboratories, but approximates to sodium 137 mmol/l, potassium 4 mmol/l, calcium 3 mmol/l and chloride 142 mmol/l. Modifications include Ringer lactate (Hartmann’s solution) and Ringer’s acetate (similar to Hartmann’s solution but with acetate instead of lactate).

[Sydney Ringer (1834–1910), English physician]

Lee JA (1981). Anaesthesia; 36: 1115–21

rINNs,  Recommended International Non-proprietary Names, see Explanatory notes

Risk management.  Process for reducing the frequency and overall cost of adverse events, e.g. complications of anaesthesia. Consists of:

Audit is an integral part of a risk management programme, the costs of which may be considerable, although the avoidance of litigation is a strong incentive. Protocols may contribute to risk management by standardising care, although they are not universally viewed with approval.

Postgraduate issue (2010). Br J Anaesth; 105: 1–101

See also, Clinical governance; Quality assurance

Ritodrine hydrochloride.  β-Adrenergic receptor agonist, used as a tocolytic drug in premature labour.

Rivaroxaban.  Orally active direct factor Xa inhibitor, licensed in adults for DVT prophylaxis after elective hip or knee replacement surgery and, in the USA, CVA prophylaxis in non-valvular AF. More effective than enoxaparin at preventing DVT and PE, with comparable risks of haemorrhagic side effects.

Rapidly absorbed via the oral route (peak plasma concentration within 2–4 h) with 80–100% oral bioavailability. 70% undergoes hepatic metabolism (by the cytochrome P₄₅₀ system) to inactive products; 30% is excreted unchanged in urine. Thus, caution is required in patients with renal failure, and those taking drugs that cause hepatic enzyme induction/inhibition.

Rivastigmine,  see Acetylcholinesterase inhibitors

ROC curves,  see Receiver operating characteristic curves

Rocuronium bromide.  Non-depolarising neuromuscular blocking drug, introduced in 1994. Chemically related to vecuronium, with similar lack of cardiovascular effects, although tachycardia may accompany very large doses. Has been suggested as the drug of choice when suxamethonium is contraindicated. Good intubating conditions occur 60 s after an initial dose of 0.6 mg/kg; relaxation lasts for about 30–40 min (about 20 min after 0.45 mg/kg). During a rapid sequence induction, an intubating dose of 1–1.2 mg/kg is advocated by some; it produces better intubating conditions in a shorter time. Supplementary dose: 0.15 mg/kg; effects last for about 15 min. May be infused iv at 0.3–0.6 mg/kg/h after a loading dose. Primarily excreted by the liver. Cumulation is unlikely at recommended doses. Reversed by sugammadex.

Ropivacaine hydrochloride.  Amide local anaesthetic agent, introduced in 1997. Chemically related to bupivacaine (a propyl group replacing a butyl group) but less lipid-soluble and less toxic, being associated with less severe CNS and CVS adverse effects. pK_a is 8.1. Presented as the (S)-enantiomer (see Isomerism). Used in 0.2–1.0% concentrations; initially reported to be approximately equipotent to bupivacaine in terms of analgesia whilst producing less motor block, e.g. for epidural anaesthesia. However, this is disputed, the reduced motor block seen with ropivacaine being related to its lower potency and thus selection of non-comparable solutions in comparative studies. In addition, comparable concentrations contain slightly less ropivacaine than bupivacaine.

Has vasoconstrictor properties; thus relatively unaffected by addition of vasoconstrictor drugs. About 94% protein-bound; undergoes hepatic metabolism with 1% excreted unchanged in the urine. Has about 40% greater clearance than bupivacaine. Maximal safe dose is estimated at 3.5 mg/kg.

Rotameter.  The trade name of a type of flowmeter commonly used on anaesthetic machines; first used in the 1930s.

Rotational therapy (Kinetic therapy).  Technique in which critically ill patients are turned laterally from the horizontal to an angle of about 40°, often several times per hour on a programmable bed. Thought to reduce the incidence of nosocomial pneumonia, decubitus ulcers, DVT and PE. Also reported to shorten duration of both IPPV and ICU stay. May share mechanisms of action with prone ventilation techniques. Compared with the prone position, it has less chance of accidental displacement of tubes and catheters/cannulae, damage to eyes/face/limbs, stimulation of coughing and cardiovascular instability. Accessibility to the patient remains good.

Goldhill DR, Imhoff M, McLean B, Waldmann C (2007). Am J Crit Care; 16: 50–61

Rowbotham, Edgar Stanley (1890–1979).  English pioneer of anaesthesia. With Magill, developed tracheal intubation, including blind nasal intubation, and endotracheal anaesthesia. Also pioneered basal narcosis with rectal paraldehyde, and local and intravenous techniques. The first anaesthetist in the UK to use cyclopropane. Designed several pieces of apparatus, including a vaporiser, airway, local anaesthetic needles and other equipment. Latterly worked at Charing Cross, London. Particularly interested in anaesthesia for thyroid surgery.

Condon HA, Gilchrist E (1986). Anaesthesia; 41: 46–52

Royal College of Anaesthetists.  Arose from the granting of a Charter to the College of Anaesthetists by Queen Elizabeth II in March 1992. Regulates and promotes research, training, education and maintenance of standards in anaesthesia. Administers the FRCA examination. Has around 6500 Fellows (including overseas); together with Members (non-trainees without the Final FRCA, a membership category introduced in 2001) and registered trainees, this amounts to ~12 000 Members in total. Created the Faculty of Pain Medicine in 2007 and the Faculty of Intensive Care Medicine in 2010. The British Journal of Anaesthesia has been its official journal since 1990; it also publishes guidelines, a regular Bulletin and CEPD Reviews.

Spence AA (1992). Br J Anaesth; 68: 457–8

R–R interval.  Time between successive R waves on the ECG. Thus heart rate =

Normally varies by less than 0.16 s at rest (sinus arrhythmia). Useful in the diagnosis of autonomic neuropathy.

RT,  Reptilase time, see Coagulation studies

RTS,  see Revised trauma score

Rule of nines.  Guide to the percentage of body surface area represented by various parts of the body; used in assessment and treatment of burns:

For small areas, the patient’s palmar surface of the hand and fingers represents about 1% of surface area. For children, proportions of body parts vary with age, with the head comprising up to 18% in infants (and the lower limbs contributing proportionally less); for accurate assessment specialised charts should be used.