practical prescribing. OLIVER The hands-on guide to practical prescribing / Oliver Jones, Nandan Drugs—Prescribing—Handbooks, manuals, etc. 2.
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During clinical training, this knowledge is extended into the use of drugs as applied to disease states with more explanation of mechanism of action. What this book is for This book aims to address the very hands-on practical aspects of prescribing. It is not an exhaustive list of drugs, their indications, contra-indications, side-effects and dosage. Nor is it a manual of medical care. These books already exist and could not be improved by us. More and more hospitals are developing local protocols, hospital formularies and guidance for junior doctors.
These are invaluable and should be consulted. This book aims to give general reasonable advice on how to manage many practical aspects of prescribing. Any doubts about management should trigger consultation of texts such as the BNF, discussion with colleagues and pharmacists and advice from senior colleagues. We took the problems that we had encountered, problems that our colleagues encountered and issues brought to our attention by junior members of the team and concentrated on these.
There will be omissions for some readers and too much detail for others. Practical aspects of how to prescribe As medical students, we are taught about drugs, how they work and when they should or could be prescribed. However, how do you actually write a prescription so that it is effective, safe and reliable? This is covered here. In-patient prescribing Before you start Always check that the patient in the bed corresponds to the name on the drug chart you are holding. You should not rely on the often inaccurate information either in the notes or written on the chart itself.
Practical prescribing Apart from the name of the drug itself, you will have to consider the dose, the route of administration and the frequency and maximum dosage permitted. Write quantities in grams if over a gram; if less than a gram but more than a milligram, write as milligrams; if less than a milligram, write as micrograms.
All may be mistaken for mg and so the full and unambiguous microgram should be used. If necessary, 2 always precede a decimal point with a zero i. The term units should not be abbreviated to U. However, some abbreviations are frequently and safely employed; the common ones are listed in Table 2. Their full name, hospital number and date of birth should be written in as a minimum. There are, broadly speaking, four ways to prescribe a drug and each has its own section on a drug chart. This section is usually on the front of the chart.
In addition to dose and route of administration, the time and date on which the drug is to be given should be entered. An example of such prescribing would be single-dose antibiotics as prophylaxis prior to an intervention. This section is used for prescribing medications that should be given on a regular basis, at the same dose and at the same time on every day. This section of the chart includes a column where the timing of doses should be stated. An example of a type of drug commonly prescribed in this manner would be an antihypertensive drug. The patient or the nursing staff will use their judgement on when these drugs are required.
Fluids may be prescribed on this section in some hospitals, although in others a separate form is used. Routes of administration Oral medications given by mouth These are absorbed from the gastrointestinal tract and can be affected by hepatic metabolism prior to release into the systemic circulation. Some drugs need the acid environment of the stomach and will not be absorbed if there is concurrent use of antacids or acid suppressants. Subcutaneous This route is commonly used for vaccination.
It has unpredictable absorption and is only suitable for low volumes of water-soluble agents. Insulin is probably the most common of the regularly used subcutaneous agents. Intramuscular Intramuscular drugs can be rapidly absorbed. This may lead to a highly variable plasma concentration. Also, the route can be very painful and should be restricted to low volumes only. Some antibiotics can be given intramuscularly.
Per rectum Most drugs can be formulated for rectal administration. The reason this route is not frequently used is largely social acceptance. It is invaluable in cases where oral prescriptions are not tolerated. Buccal, transdermal These are also viable methods. The transdermal route is useful for slowrelease preparations such as glyceryl trinitrate GTN or hormone replacement therapy HRT.
The buccal route is for rapid absorption and fast-acting effects. Inhalation This route is largely limited to the treatment of airways diseases including infections. In resuscitation situations, adrenaline epinephrine can be given via endotracheal ET tubes into the lungs. Topical Used where high local concentrations of drug are needed with few systemic side-effects. Drug preparations Some drugs are formulated to be slow release and the mechanisms for this vary.
Some are coated to be slowly broken down, others have a more complicated system. If any slow-release drug is chewed or crushed, the slow-release function may be destroyed and this is very important if using a nasogastric tube. The new patient Routine admissions For many junior doctors, clerking of routine or emergency admissions to hospital forms a large part of their daily workload. Patients who are routine admissions to hospital should generally continue their drugs, which should be written onto their drug charts, unless these are likely to interfere with their reason for admission beware particularly anticoagulants and interventional procedures or surgery.
It is worth remembering that, although a medication may be prescribed, this does not mean that it is taken by the patient. Furthermore, what is written on the box of tablets may not correspond to how the patient actually takes the drug. Other sources of information include computer printouts and handwritten lists. Relatives especially carers may also be reliable sources of information. Emergency admissions In general, patients admitted as an emergency should also take their regular medications as described above. However, the following additional issues should be considered.
Drugs could be given via another route, such as intravenously but, in practice, anaesthetists will often be keen that important drugs, such as antihypertensives, are still given with a sip of water. Out-patient prescribing When writing a prescription for medications for the patient to take away from the hospital, the general principles for in-patient prescribing apply.
There are additional considerations, which centre on the issue of length of treatment course. The out-patient script should state this clearly, e. In such cases, it is important that the GP via discharge summary or clinic letter and the patient by verbal advice or copy of the correspondence to the GP are aware that the treatment must be continued. The senior nurse will be able to locate these for you. Controlled drugs Out-patient prescriptions for controlled drugs have special requirements.
The following are legal requirements that must be included on the prescription: Brand name or generic name? It is generally better practice to use the generic non-proprietary name of a drug. It is also common practice for cheaper formulations to be substituted, when available. Some drug formulations affect the bioavailability of active agent and in such cases prescribing by brand is acceptable, e. Further considerations If in doubt, ask your colleagues or the hospital pharmacist.
Accurate prescribing and neat handwriting minimize any confusion. They also reduce the frequency of bleeps to you from pharmacists and nursing staff. These additional drugs might include analgesics, night sedation, antiemetics and nebulizers. This may prevent a phone call from a nurse able to manage a patient but powerless to give them the drug they require.
However, the indiscriminate and careless prescribing of these drugs should be discouraged. It may be found on the web at http: It is published twice a year. Both brand names and generic names are listed. While the BNF is comprehensive, inclusion of a drug does not imply that the organizations and committees behind the book endorse the drug. Indeed, drugs considered less suitable are marked with a symbol.
However, the BNF may not list those medicines promoted for purchase by the public. All drugs are listed in identical fashion as shown in the box on p. Unlicensed indications are included for some drugs e. Cautions and contra-indications for each drug may be found in the Appendixes at the end of the BNF. Appendix 1 is an alphabetical list of drug interactions, where the symbol denotes a potentially serious interaction.
Reference is also frequently made to Appendixes 2 and 3, which give further information on prescribing for patients with hepatic and renal impairment, respectively, while Appendixes 4 and 5 advise on drug prescribing in pregnancy and to patients who are breast-feeding. Background to a clinical condition and therapeutic options The heart of the BNF comprises 15 chapters, listed on the contents page, of conditions, drugs and preparations divided by organ e. Individual drugs are listed in sections, with others similar either in chemical structure or clinical indication. The pharmacist may substitute cheaper formulations if appropriate.
It is worth noting that the prices listed in the BNF do not correspond precisely to the cost to the National Health Service NHS , nor do they represent the cost of private prescriptions or of purchasing the drugs over the counter. There are a number of other pieces of information in the BNF. The general layout for drugs listed in MIMS is as shown in the box below.
Drugs which may be affected by or affect other drugs ADR: Most frequently seen adverse effects or most serious rarely seen adverse effects 4: Drug interactions Drug interactions are both common and probably under-recognized. They are listed in Appendix 1 of the BNF. Knowledge of a drug interaction should not necessarily deter you from prescribing two drugs together.
Often, all that is needed in such circumstances is closer clinical management or adjustment of dosage. Furthermore, drug interactions may even be used therapeutically, as in the treatment of poisoning. This chapter cannot be comprehensive in its tackling of such a large subject, but some of the principles are discussed. Types of drug interactions In general terms, there are two types of drug interactions: Drug interactions may be divided into 10 three main types: Pharmaceutical interaction This is the interaction of drugs on a chemical non-pharmacological level. One such example is the formation of a complex between thiopental thiopentone and suxamethonium, which cannot therefore be mixed in the same syringe.
Simple strategies should reduce the risk of this type of interaction, and include giving drugs as bolus injections where possible, avoiding the mixing of drugs prior to administration except when this is known to be safe inevitably, many drugs have to be reconstituted in dextrose or saline and making up infusions immediately prior to use. Pharmacodynamic interaction This is the increase or decrease in the effect of one drug without an effect on the drug concentration at its site of action.
This is often predictable from a knowledge of the pharmacological mechanism of action of a drug and often occurs through competition at either receptor site or by an action on similar physiological systems. An example of this type of interaction is that between loop diuretics and digoxin. The consequent increased glycoside binding enhances the risk of arrhythmias. Pharmacokinetic interaction This is the increase or decrease in effect of one drug through alteration of the drug concentration reaching its site of action by a second drug.
There are four aspects of drug pharmacokinetics that may be affected: Absorption This occurs when two drugs form an insoluble complex seen sometimes with antacids and prednisolone or because one drug alters gut motility, as seen with drugs such as loperamide or metoclopramide, and affects the time available for drug absorption to occur. This interaction is sometimes exploited usefully as when lidocaine lignocaine is combined with adrenaline for subcutaneous local anaesthesia.
The vasoconstrictor effect of adrenaline reduces absorption and hence indirectly redistribution and metabolism of lidocaine, prolonging the anaesthetic effect of the latter drug. Distribution This type of interaction frequently occurs between two drugs that are extensively protein bound in the plasma. One 11 drug may be displaced from its proteinbinding site by a second. Thus, most serious interactions are seen when displacement from plasma proteins occurs in addition to other effects such as inhibition of drug metabolism.
An example of this is sodium valproate, which not only displaces phenytoin from plasma proteins but also reduces the rate at which it is metabolized. Metabolism This most frequently occurs when one drug affects liver enzymes such that the metabolism of a second is changed; e. The resultant reduced plasma levels may result in pregnancy.
Enzyme inhibitors also exist. The most common drugs in this category are those with an action that includes inhibition of isoenzymes of cytochrome p, e. Excretion This is most commonly seen in those drugs sharing a common transporter mechanism in the kidney. An example of this is the lithium accumulation seen in patients treated with concomitant diuretics. Identifying possible drug interactions Drug interactions may manifest in a number of different ways, including lack of effect of a newly introduced drug or clinical deterioration in the patient.
They are more likely in those patients taking many drugs simultaneously especially, therefore, the elderly and seriously ill. Patients with hepatic or renal impairment are also at increased risk as metabolism and excretion are likely to be compromised. Certain types of drugs are more likely to trigger clinically important interactions, particularly those drugs with a narrow therapeutic index a small change in drug concentration resulting in a substantial change in clinical effect.
There are three types of drugs that should alert you to the possibility of drug interactions: This may occur through a number of different mechanisms but commonly involves a drug increasing or decreasing enzyme activity with resultant effects on the plasma levels of a second drug. Important potential drug interactions There are a number of drugs that are used for treating the same disease or condition which interact.
Some of these are listed in Table 4. Monitoring of drugs, overdose and toxicity What is therapeutic drug monitoring? Therapeutic drug monitoring is a process by which the blood concentration of a drug is maintained at a therapeutic level. It involves assaying for the drug or its metabolites at various points on the dosing schedule. Certain drugs or their clinical effect require close monitoring. If the clinical effect can be readily measured e.
This is not the case for drugs that are used to suppress overt symptoms such as seizures, depression and transplant rejection. Measurement of the concentration may be needed for any drug that has: If loading doses have been given, steady state will be achieved faster. Sampling at one point the same every time in the dosing schedule is usually enough; the time at which there is least variability is the pre-dose or trough concentration. For drugs with short halflives in relation to the dosing interval, samples should be collected pre-dose. For drugs with long half-lives e.
For some drugs, both peak and trough levels are useful e. Values obtained can only be interpreted in the context of the individual situation. The laboratory will help to establish or revise the dosing schedule with these in mind. Has steady state been achieved? Pharmacodynamics will be affected and interactions accounted for, such as protein binding, metabolism and clearance.
Renal or liver dysfunction will affect dosage. Dose forecasting is a system by which future plasma concentrations can be extrapolated from current values. For gentamicin, it has become increasingly common to have a once daily regimen followed by daily checks of plasma levels before further doses are given. Local policy regarding antimicrobial protocols should be sought.
Management of drug overdose and toxicity The treatment of drug overdose and attempts at deliberate self-harm forms an important part of emergency medical therapy. There are a number of principles of treatment common to any episode of drug toxicity or overdose.
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Antidotes, where available, may be used. The emergency treatment of poisoning in the BNF gives treatment algorithms for common toxins. The National Poisons Information Service gives upto-date advice on any toxicology-related subject. It is good practice to consult with this service in all but the most common cases Table 5. They will provide verbal or faxed, if requested advice from their database regarding therapy. This service is linked to drug surveillance systems see Chapter 6.
The telephone number for the National Poisons Information Service is Minimum toxic dose Special considerations Antidote therapy Lower toxic dose in liver damage or high alcohol intake or recent previous overdoses. Watch INR for at least 3 days after overdose and continue therapy until consistently below 1. Beware of hypoglycaemia Activated charcoal is useful but patient will be nauseated. Fluids, correction of acid—base disturbances and haemodialysis are mainstay. Alkaline diuresis is no longer advised but may be needed if facilities for dialysis not available Cardiogenic shock probable so HDU-type environment needed 3 mg atropine i.
May mask true cerebral irritation or evidence of encephalitis Full supportive therapy needed. Benzodiazepines can help in early stages. Activated charcoal can be used acutely. Arrhythmias can be fatal Activated charcoal is useful. No antidote but very close monitoring and supportive therapy. Airway may become compromised with a high risk of aspiration Benzodiazepines Tricyclic antidepressants HDU, high dependency unit; i. Treat high-risk patients immediately. Do not wait for levels. Activated charcoal is only really useful if taken within 1 h for most drugs. It is also used in cases of active elimination such as carbamazepine, theo- phylline and quinine.
Gastric lavage is no longer recommended in most cases but, if used, the airway should be formally secured or the patient fully alert. ADRs may be divided into a number of different categories, listed in Table 6. These effects occur in many patients and are a manifestation of the mechanism of action of the drug.
By contrast, type B reactions occur only in susceptible individuals and are not dose-related. Frequency of drug reaction ADRs are common. In a recent single practice study, GPs estimated that the presenting symptom of 1. Assessing likelihood that an adverse drug reaction has occurred An ADR should be considered in any patient taking prescribed or overthe-counter medications; however, they are more common in young and middleaged women.
Assessing the likelihood of an ADR involves taking a careful and detailed history about clinical symptoms and their timing in relation to drug exposure. ADRs may occur immediately, and typically these types of reactions are anaphylaxis, bronchospasm and angiooedema. Later reactions are also seen, although these are more commonly rashes and haematological changes e.
Further clues about the relation of an adverse event to a particular drug may be obtained when the timing of peak plasma drug concentration is considered. There may be a history of previous exposure to the drug. Finally, there is also the option of the reintroduction of the suspected drug. Management of a suspected adverse drug reaction For type A reactions, the management is simply reduction in dosage or withdrawal of the medication altogether.
By contrast, type E reactions require reintroduction of the drug and more gradual withdrawal.
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Type of reaction Mnemonic Features A: Addisonian crisis after steroid withdrawal irreversible or at best only partially reversible on drug withdrawal. Type B reactions are uncommon, unpredictable and show high morbidity and mortality. If the reaction is mild, no further intervention may be necessary. Urticarial rashes and, to a lesser extent, non-urticarial rashes may be treated with antihistamines, such as chlorphenamine chlorpheniramine , and an adrenocortical steroid. In more severe cases, these drugs may be given intravenously or intramuscularly. If angio-oedema develops with threatened laryngeal oedema, adrenaline should be considered see below.
Oxygen should be administered via a face mask. Chlorphenamine 10—20 mg should also be administered by slow intravenous injection, and hydrocortisone — mg , although the onset of action of the latter may not occur for several hours. Anaphylaxis Subsequent management Anaphylaxis is a medical emergency. Senior help should be summoned, including an anaesthetist. Avoidance of subsequent exposure to the drug is clearly important and patient education is very important in this regard.
In rare cases, desensitization should be considered. This is particularly appropriate for patients who have had immunoglobulin E IgE -mediated reactions to penicillin and require the drug for treatment of serious infections such as meningitis or endocarditis. This may, in theory, be carried out orally or intravenously, although the former is probably preferred as it less commonly results in serious life-threatening reactions.
Reporting of an adverse drug reaction Although all drugs are evaluated prior to marketing Phase I—III trials , ADRs either of low frequency or found only in subgroups of patients may not be detected until post-marketing surveillance Phase IV. Part of that surveillance system in the UK requires doctors to report any suspected adverse effects to the Medicines Control Agency by using the yellow cards at the back of the BNF.
It is important therefore that all doctors take an active role in submitting such data. Further post-marketing surveillance is carried out by various agencies who contact doctors directly for information. Every unexpected adverse reaction should be investigated and usually reported by the yellow card system. Consultations owing to adverse drug reactions in a single practice. Br J Gen Pract ; Br Med J ; The differences are both in the function of their body systems and their constituents.
If in doubt, it is reasonable to check with your ward pharmacist, but for more specialist prescribing close liaison with a paediatrician may be necessary. Many drugs used in children, however, are not licensed for paediatric usage. Scaling down of the dosage to paediatric levels tends to be based on body surface area rather than body weight. Routes of administration Whenever possible, medications should be given orally, either in liquid or soluble form, and many older children are capable of taking tablets. In surgical patients, who are nominally nil by mouth, it is almost always acceptable for them to take oral medications with just a sip of liquid.
If a child is prescribed a liquid medication, it is important always to 20 state the strength of solution and the amount to be taken. Many of these liquid preparations contain large amounts of sugar, which may be an issue in diabetics and may promote dental decay in patients on long-term treatment. Neonates and infants have relatively little skeletal muscle and fat and therefore intramuscular and subcutaneous administration tends to result in unpredictable plasma drug levels.
These routes are therefore generally avoided, with intravenous or rectal administration being preferred when the child is unable or unwilling to take oral medications. Pharmacokinetics Absorption Oral absorption in children is broadly similar to that seen in adults. Transdermal absorption may be further increased in children with excoriated or burnt skin, but with occasional reports of toxicity.
Distribution Young children, infants and neonates have a higher percentage of total body water, although in reality this has little overall effect on drug levels as it is cancelled out by other differences such as rate of elimination. In neonates, the blood—brain barrier is more permeable to drugs than in adults, which explains why children are more susceptible to many centrally acting drugs.
Metabolism and excretion The enzyme systems in the liver responsible for drug inactivation are present in the neonatal liver but are less effective. Therefore, drugs and their metabolites eliminated by renal excretion tend to accumulate in this group. Aminoglycosides, penicillins and diuretics are examples of drugs that fall into this group. This is in part related to high tissue drug levels, polypharmacy and inappropriate timing of doses. Compliance may also be an issue in some cases.
Drugs that are excreted by the kidneys, such as gentamicin or lithium, may need to be prescribed in lower doses. Pharmacokinetics General issues Absorption This is not substantially different in elderly people. Distribution Elderly people may have very low body weights and are thus susceptible to overdose. Furthermore, they tend to have a lower percentage of total body water but a higher proportion of fat compared to young adults. There is therefore a risk of accumulation of lipid-soluble drugs in more elderly patients. Metabolism and excretion The metabolism of some drugs is variable in older people relative to younger people.
The metabolism of other drugs appears to be relatively unaffected by age e. Mild confusion, weakness and an altered bowel and bladder habit are common. The morbidity and mortality of such bleeds are greater in this group. A proton-pump inhibitor is then the best treatment. In elderly patients who are likely to require long-term NSAID treatment, prophylactic use of a proton-pump inhibitor should be considered.
Diuretics and a resultant low volume state may manifest as postural hypotension which may lead to falls and reduced mobility. Electrolyte disturbances are also more frequent. Sedatives and anxiolytics can induce confusional states. Consider that the patient may prefer liquid or syrup forms of the medication you are prescribing. Consider also that the elderly patient may need assistance in the physical act of taking medications, either because of poor vision or arthritis. Long-acting agents that can accumulate such as glibenclamide should be avoided.
Follow-up Follow-up should also be considered: A Dosette box, district nurse supervision or even day hospital care may all be needed. Conception, pregnancy and breast-feeding Prescribing for women of childbearing age should be done with care. Many otherwise safe drugs can have effects on the fetus, while others affect fertility in men and women. The BNF Appendix 4 has a comprehensive list of medicines and advice on prescribing during pregnancy, while Appendix 5 covers breastfeeding.
In order to clarify your intentions when prescribing, it is useful to consider the following points. The drug, conception and the fetus: Treatment of the pregnant patient In an emergency, the clinical priority is the woman but it is vital that adverse 24 effects to the fetus be stated immediately to the patient and family if unavoidable. Drugs at term may affect the process of delivery, the neonate, or both.
If they are needed, the patient must be advised to take measures to avoid conception. If pregnancy does occur, specialist opinion should be sought immediately and the risks evaluated as above. Neural tube defects are possible but the incidence can be reduced by using smaller doses of single drugs and by prophylactic use of folate supplements. The risks of a seizure during labour are serious. This list is not comprehensive. A woman with a recent history of thromboembolism or deep vein thrombosis is at risk of a further event during pregnancy, which may be fatal.
On balance, the risk of bleeding is acceptable as it is small and, with good surveillance and immediate therapy, dangers can be minimized. In general, patients needing anticoagulation who are or who are at risk of becoming pregnant should be offered heparin therapy. Low molecular weight heparin can be used see Chapter Methotrexate This is an example of a drug that may cause fetal abnormalities even after cessation.
Contraception should be used by couples if either partner has been on the drug during the preceding 3 months.
The Hands-on Guide to Practical Prescribing
This is a complex area and counselling by a specialist clinician is essential. Breast-feeding For breast-feeding, the situation is less critical as alternative methods of feeding exist. Here the effects may be on maternal lactation dopamine agonists or, more often, passage of the drug or its active metabolites into breast milk with resultant effects on the child.
A list of common drugs at standard doses that may have effects when given to breast-feeding women is shown in Table 9. Finally, local anaesthetics are considered. It is becoming increasingly common that patients for elective procedures will have been assessed at a pre-admission clinic. These are designed to ensure that the patient is in the best condition for any operation.
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It is also good practice to inform the GP of the likely operation date and arrange for any further assessments. Cardiovascular drugs Generally, these should all be given, even if the operation is in the morning. Calcium antagonists can have additive effects on myocardial depression with induction agents, so inform the anaesthetist and observe local policy.
Respiratory drugs Maintenance levels of inhaled steroids, bronchodilators and antihistamines should be continued. The anaesthetist should be alerted to this. Concurrent medications Usually, medications that the patient is taking preoperatively should be continued until the day of surgery and even given on the morning of surgery itself. Giving these medications with a sip of water even in a patient who is nominally fasted is safe and appropriate. Antidepressants These should be taken. Lithium at high doses can impair renal function and lead to a range of problems so adequate hydration is important.
Check levels before the procedure and closely monitor renal function afterwards. This should have been addressed in the out-patient clinic when the patient was booked for theatre, possibly with transfer to another drug. The anaesthetist, GP and psychiatrist may all need to be involved in this decision. Antiplatelet agents There is an increased risk of bleeding with antiplatelet agents e. For major operations or those with a high bleeding tendency e. The risk of central nervous system CNS embolic damage or ischaemic heart disease IHD is small compared to possible poor haemostasis.
The need for antiplatelet agents with other procedures, such as cardiac surgery or coronary artery stenting, may be higher. Anticoagulation This is a very important aspect of perioperative care. It is covered in detail in Chapter Steroids A history of steroid intake within the previous 6 months should lead to the consideration of steroid supplementation in the perioperative period. Although patients may have been steroid independent for a number of weeks, they may have an impaired stress response to surgery and need to be covered for this see Chapter Diabetic medications See Chapter Oral contraceptive pill and hormone replacement therapy Oestrogens increase the risk of thromboembolism and so patients on the oestrogen-only pill, combined pill or HRT should discontinue this 1 month preoperatively.
They should be counselled about the need to use alternative forms of contraception. Patients taking the progesterone-only pill do not need to stop this. In patients undergoing emergency surgery, adequate thromboembolism prophylaxis, employing both mechanical methods and heparin, should be used see Chapter Anaesthesia and premedications Although anaesthesia is a speciality in its own right, there are a number of aspects of which every doctor should be aware. Anaesthetics Anaesthesia may be general, regional, local, or a mixture of these. Muscle relaxants used are depolarizing e. If a patient has had a depolarizing drug will have experienced generalized muscle contractions at the point of induction and may complain of aches and pains on waking.
If the muscle relaxants have not worn off adequately or been fully reversed with a cholinesterase inhibitor e. Low tidal volumes and poor oxygenation may be seen. This should have been looked for and excluded before return to the ward. Induction of anaesthesia can be through any route but is almost universally intravenous or by inhalation. Etomidate has a less cardiac depressant effect and is used in elderly or unstable patients. Thiopental thiopentone is a potent barbiturate which is also used as an induction agent. The exact drug used is decided by the anaesthetist on an individual basis.
It is at the time of induction of anaesthesia that cardiovascular instability will most often show itself. Anaesthesia can be maintained through a number of routes. Volatile agents are most commonly used in the UK to acheive this. There are a number of these: They have a spectrum of sideeffects. The most apparent of these is a hangover sensation and nausea. Analgesia intraoperatively is likely to be a combination of opiates, NSAIDs and regional or local blocks. Postoperative pain relief depends very much on 29 the type of procedure and the anaesthetist see Chapter Premedication These are drugs given close to the operation time, i.
You might consider use of a bronchodilator as a premedication, antibiotics or increase in steroids. Although it is still done in many areas, avoid using deep intramuscular premedications. They are painful, have unpredictable absorption and better routes are often available. Clarify the need for this with your anaesthetist. Often it takes much longer to wake up fully after the operation. This may particularly be an issue in day care patients.
Hypertension If the blood pressure is genuinely elevated, check to see how these values compare to normal for the patient. Have the normal antihypertensives been taken and time allowed for them to act? If pressure is still elevated, beta-blockers, alpha-blockers or nitrates can be used. Usually at this point it is wise to inform the anaesthetist, who can assess the anaesthetic risks of the case and postpone surgery if necessary.
In the majority of general cases an elevated blood pressure will not matter greatly, but in some operations it is vital to have low controlled systolic pressures to aid in haemostasis e. In adrenal surgery, pressure should be well controlled with both alpha- and betablockade before theatre.
Metoclopramide is ineffective in opiateinduced nausea. Cyclizine 50 mg i. For severe symptoms, ondansetron 8 mg i. Deranged clotting See Chapter Labile blood glucose This should really have been addressed much earlier. If glycaemic control has just become unstable normal range HbA1c but very high BM value , then always check if anything else has happened. Occult myocardial infarction is often a cause for such a problem. A gentle adjustment is usually enough see Chapter Sedation and hypnotics There are a number of procedures, such as endoscopy, during which sedation may be desirable.
There is a choice of different medications used for this, some of which are listed below. Midazolam This is a short-acting water-soluble benzodiazepine that provides sedation and amnesia but not anaesthesia. It has a shorter duration of action than diazepam. It can be given intravenously, usually starting with 2 mg initially then increasing after 1 min or by 1-mg increments until adequate sedation is achieved.
It may cause respiratory depression and so oxygen saturations should be measured in these patients. There is considerable interpatient variability in sensitivity to these agents. Excessive doses of midazolam or if the drug is given too fast may cause respiratory depression or arrest. Apart from causing nausea, vomiting and agitation, it may rarely cause convulsions. Opioids These drugs may aid both sedation and analgesia in patients undergoing procedures such as reduction of dislocations or fracture manipulation.
Antimuscarinics These drugs may be used in endoscopy or radiology, predominantly to reduce smooth muscle spasm. They may cause confusion, vomiting and bradycardia. Local anaesthetics Local anaesthetics cause reversible blockade of the conduction of impulses in nerves by blocking sodium channels in the nerve membrane. Most local anaesthetics are in the form of a base combined to a hydrochloride.
There are a number of considerations when choosing a local anaesthetic agent. A long duration of action is not always desirable as this may delay patient mobilization or discharge. Lidocaine has a rapid onset of action and moderate duration of effect. By contrast, bupivacaine has a slower onset but a longer duration of action. For example, lidocaine is available in 0. To increase the duration of action of local anaesthetics, vasoconstrictors, usually adrenaline 1: This reduces the rate at which the local anaesthetic is taken up into the circulation.
The maximum dose of adrenaline is micrograms 1: Topical local anaesthesia is useful for skin and mucous membranes. In general, cocaine, lidocaine and prilocaine are the most useful for this purpose. The onset of action is usually 5—10 min and lasts for up to 1 h. It should be applied 1 h in advance and is commonly used prior to taking blood or the placing of intravenous cannulae.
An occlusive dressing will stop it being rubbed off. Maximum doses and toxicity Maximum doses are given for each local anaesthetic in Table Maximum plasma levels of local anaesthetics usually occur at around 30 min. Signs of toxicity include mild sedation and circumoral paraesthesia. At higher levels, convulsions, cardiovascular collapse and rhythm disturbances may be seen. Local anaesthetics with or without opiates are used to give spinal and epidural anaesthesia Table This percentage is slightly lower for females, as they tend to have more body fat. Water moves across the cell membrane if there is a difference in osmolality between the sides.
The number of particles determines osmolality, not their size: It is useful as the basis for providing basal replacement as it has 30 mmol of sodium and chloride with the glucose being rapidly metabolized leaving water. Hyponatraemia may occur with overuse of dextrose saline. Thus, normal saline tends to distribute throughout the extracellular space without any net movement of water into the cells.
Colloids These include albumin, starches and gelatins. The capillary membrane is impermeable to colloid and so the solution remains within the intravascular compartment for longer. Most of these carry a high salt load and this must be considered when planning therapy. This is in health and takes into account losses in sweat, faeces and urine. The very presence of a patient in hospital suggests that basal replacement alone may not be adequate to keep pace with increased losses. Additional requirements One of the most common examples of a patient with additional requirements occurs in bowel obstruction, vomiting or in those with a high nasogastric output.
High-output stomas can lead to losses in bicarbonate, potassium, chlorine, sodium, water and protein. Bleeding will cause a proportionate loss of everything. A spot assessment of urinary biochemistry, including pH, may help to guide replacement. It will buy you time to assess the patient further and plan therapy. Colloids stay in the vascular space for longer and may be more appropriate after the initial stage.
Further information may be obtained from blood tests and assessing renal function and haematocrit. In special cases, total urine output of electrolytes may need to be measured. However, if some other intervention is planned, it may need to be faster. One such example would be the patient who needs a laparotomy for peritonitis. Fluid replacement must be as rapid and effective as can safely be achieved before peritonitis and sepsis supervene. Alternatives to central lines include femoral lines. These can be used to measure central pressure trends but are more prone to changes in intraabdominal pressure compared to an internal jugular or subclavian line.
This may be true in health and for the walking wounded, but for a considerable number of in-patients this is not the case. It is easy to imagine a scared old lady in a busy accident and emergency department with tepid water in a plastic jug, just out of reach. She may be scared to drink as she is worried no-one will be able to take her to the toilet.
Sadly, this happens every day. Fluids should be prescribed with any additives clearly indicated and the rate to be given noted. Supplements Maintenance of plasma potassium levels is important and this can be achieved using oral or intravenous supplementation. The quantity of potassium that may be given intravenously over 24 h depends on the type of access.
These are maximum values and if there is a need to give more potassium than these amounts, then a central line is appropriate and a more thorough review of the case may be 36 CHAPTER 11 Table Calcium supplements may be given as chloride and gluconate salt. Both come as mL ampoules and calcium chloride also comes as a minijet. Magnesium replacement is dependent upon indication.
The initial dose is 8 mmol over 20 min for rhythm disturbances and 72 mmol over 12—24 h is the usual replacement rate Table Nutrition Up to half of patients in hospital may show evidence of malnutrition as a result of their underlying disease or their social situation. Malnutrition may be compounded by the process of hospital admission and treatment such as surgery.
Poor nutritional status is associated with a number of problems including poor wound healing, reduced muscle strength, unbalanced electrolyte compositions and dehydration. The dietetic services in hospitals should be considered an integral part of the team and their advice sought early. Assessment of nutrition is not simple. Some of the methods are shown in Table Therefore, it is good practice to assess all patients coming into hospital. Perhaps the single most important issue in nutrition is that patients with a normal or near-normal gastrointestinal tract should be fed via the enteral route.
In general terms, the process by which a patient is fed may be based on the following factors: Giving more than the necessary energy requirement may result in hyperlipidaemia and hyperglycaemia. Malnutrition in patients with normal gut and able to eat normally These patients should be encouraged to eat. Note that the examples may be affected by many factors other than nutrition. Method Example Anthropomorphic measurement Triceps skinfold thickness Dynamometric measurement Hand grip strength Biochemical measurement Serum albumin Immunological measurement Lymphocyte count an adequate nutritional intake.
It is useful to ask nursing staff to keep a chart of food intake both food ordered and amount of each meal eaten. Favourite meals can be brought in by the family but there are reheating rules to be followed, so seek out local policy.
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There is a large range of cartons of liquid supplements available. One of the most commonly used is Ensure, which has kcal in mL volume and contains Juices, powder supplements and milk shakes have all been formulated. It is the policy of certain units to supplement routinely the calories in a standard hospital meal. This is especially true in elderly care wards. These are individualized food packets. The exact contents vary but include a selection of fruit, biscuits, crisps, yoghurt and sandwiches.
This is designed as a snack and should not be used repeatedly in lieu of a meal. These do not need to be prescribed. Malnutrition in patients with normal gut but unable to take an oral diet Routes of access Many patients have a relatively normally functioning gut but have an impaired ability to take in food. This may be because they have swallowing problems e.
In such patients, enteral feeding via a nasogastric or nasojejunal tube, percutaneous gastrostomy or feeding jejunostomy is appropriate. Apart from simplicity and avoidance of venous line-associated morbidity, this approach has several advantages over parenteral nutrition. Fine-bore tubes are more comfortable for longer term use. Feeding is commenced at a slow rate e. Sometimes, gastric stasis may hinder enteral feeding and this manifests as abdominal distension, high-volume nasogastric aspirates or vomiting.
In such circumstances, promotility agents such as erythromycin mg b. For any surgery after which prolonged postoperative enteral feeding is anticipated, a feeding jejunostomy is often placed at the time of surgery. This has the advantage of being less irritant to the patient. Furthermore, after surgery the colon and stomach take the longest time to recover motility. The small bowel, by contrast, often recovers almost immediately.
Many upper gastrointestinal surgeons also favour jejunostomies because they allow feeding distal to the site of anastomosis. The overwhelming majority of patients can be adequately managed using a polymeric diet. In a small number of patients e. The nitrogen source in these feeds is from free amino acids or oligopeptides and carbohydrate is supplied in the form of glucose polymers of less 39 than 10 glucose molecules. If using a nasally placed tube, the position is normally checked by an X-ray prior to starting feeding. There is a trend towards early aggressive enteral feeding in patients.
In wellnourished patients in whom oral or enteral feeding is not anticipated within 7—10 days of surgery, consideration should be given to early parenteral nutrition see below. Malnutrition in patients with abnormal or inaccessible gut These patients require total parenteral nutrition TPN. Some of the issues associated with parenteral nutrition are considered below. Routes of access The intravenous supplements are high osmolality and should be given through a dedicated cannula in a large vein.
Some can be given peripherally but thrombophlebitis and line failure commonly occur. If prolonged use is envisaged, central access is needed. This should be clearly labelled and preferably isolated from the other lines. Lines can be tunnelled so that the exit point through the skin is remote from the site of venepuncture to reduce line infection risks. Composition of total parenteral nutrition TPN bags are normally 2.
They usually contain around kcal, provided approximately equally by carbohydrate and lipid emulsions. They also contain electrolytes, trace minerals and vitamins. The hospital pharmacist may adjust the proportions of each of these to take account of the daily electrolyte results.
The Hands-on Guide to Practical Prescribing (Hands-on Guides)
Morbidity associated with total parenteral nutrition There is considerable morbidity associated with the central lines commonly used for TPN. These are immediate complications associated with insertion, including arterial puncture, haemothorax and pneumothorax. There are also delayed complications, including linerelated sepsis and venous thrombosis. There are also metabolic complications associated with TPN, including hyper- and hypoglycaemia. Insulin regimens may be needed at the same time.
Abnormalities of plasma potassium, sodium, calcium and phosphate are also seen. Regular monitoring of electrolytes and liver function is essential. It is common to see deranged liver function predominantly cholestatic in pattern amongst patients on long-term TPN. Giving drugs via enteral feeding tube route It is not enough to just prescribe drugs to be administered via the nasogastric route or similar. Most tablet or capsule forms of drugs can be crushed and given via the tube.
Drugs that are slow- or controlledrelease preparations are unlikely to retain this quality as crushing often disrupts the delivery system. Naturally long-acting agents can be used normally. Prescribe suspensions when possible and replace slow-release drugs with short-acting agents given at increased frequency and comparable replacement doses.
This is bound to disrupt established pharmacokinetics and closer monitoring may be needed for clinical effects and therapeutic plasma levels. Absorption of drugs will be affected by the feeding regimen. Details of such drugs are beyond the scope of this book and once the treatment intentions are clear, a discussion with your local pharmacy to select the most suitable drugs in the relevant classes is advised. Once normal feeding commences, previous medicines can be reintroduced with vigilance regarding effects and levels.
Early enteral feeding, compared with parenteral, reduces postoperative septic complications: Ann Surg ; The subjective pain a patient feels may be compounded by anxiety and fear and it is important that these aspects are addressed. A regimen that on paper looks ineffective may have been providing good control of symptoms in the community.
It is often useful to ask patients to score their pain on an analogue scale of 0—10, with 0 representing no pain and 10 the worst pain they have ever felt. This is useful in assessing the response to analgesics. The basic principles of analgesia are: Acute intervention to regain control is called rescue analgesia and provision should be made for this whenever treating a painful condition. Types of analgesic drug Simple non-opiate analgesia Paracetamol This is a very good analgesic and also has antipyretic properties.
It is particularly effective when prescribed as a regular medication. It is generally safe but should be used with caution in patients with liver impairment. It is a dangerous drug in overdose. The resultant severe liver damage may not manifest itself for several days. Doses of — mg can be given with a maximum dosage of 4 g in 24 h. It also has antiplatelet activity. The hands-on consultant to sensible prescribing is a concise, easy-to-use consultant to the sensible points of pharmacology for junior medical professionals who're making the transition from learning pharmacology to prescribing medicines for the 1st time.
This new addition to 'The hands-on consultant' sequence brings jointly the middle pharmacological wisdom required by means of condo officials, dependent in how to tackle the very hands-on, useful facets of prescribing. This publication isn't designed to interchange the genuine drug info within the BNF, yet to enrich and construct upon it, in order that The hands-on consultant to sensible prescribing offers junior medical professionals with a great advisor to prescribing within the scientific setting.
Beginning with the final rules of prescribing and fundamentals of writing a prescription shape, the publication publications you thru issues corresponding to utilizing the BNF, drug interactions and tracking toxicity, prior to relocating directly to disguise either surgical and clinical themes equivalent to preoperative and postoperative sufferers, prophylaxis, organ failure and diabetes. The hands-on consultant to sensible prescribing is a problem-based e-book that covers the typical difficulties and questions a home officer may possibly come upon, and may be a useful advisor to existence at the wards.
The authors are professional registrars in medication and surgical procedure, have undertaken SHO and registrar posts within the significant specialities and in addition write and train frequently on medical pharmacology. The foreign journal for modern wonderful paintings images. Lens is a per month book that indicates the simplest and brightest images works. Lens journal follows an identical the principles laid upon by way of its predecessor, aiming to unearth and show off either top artists and rising abilities alike. Download e-book for kindle: I simply used the Microbiology half: It helped me to determine the fundamental information regarding every one computer virus and virus, getting ready me for the scientific events defined in try questions.
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