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Source Major monoterpenes Common name Botanical name (Family) Black pepper Piper nigrum (Piperaceae) a- and b-pinene buy betnovate 20gm without a prescription skin care home remedies, phellandrene Peppermint leaf Mentha piperita (Lamiaceae) Menthol generic 20gm betnovate with visa skin care hospital in chennai, menthone Oil of rose Rosa centifolia (Rosaceae) Geraniol cheap betnovate online amex skin care insurance, citronellol, linalool Cardamom Elettaria cardamomum a-terpineol, a-terpinene (Zingiberaceae) Rosemary Rosmarinus officinalis Borneol, cineole, camphene (Lamiaceae) Bitter orange Citrus aurantium (Rutaceae) (þ)-limonene, geranial Camphor Cinnamomum camphora (þ)-camphor (Lauraceae) Caraway Carum carvi (Apiaceae) (þ)-carvone, (þ)-limonene Thyme Thymus vulgaris (Lamiaceae) Thymol, carvacrol 6. Farnesylpyrophosphate can cyclize by various cyclase enzymes in various ways, leading to the production of a variety of sesquiterpenes. For example, (À)-a-bisabolol and its derivatives have potent anti-inflammatory and spasmolytic proper- ties, and artemisinin is an antimalarial drug. The following table lists just a few of these sources, and their major sesquiterpene components. Source Major sesquiterpenes Common name Botanical name (Family) German chamomile Matricaria recutita (Asteraceae) Àa-bisabolol and its derivatives Feverfew Tanacetum parthenium Farnesene, germacrene D, (Asteraceae) parthenolide Qinghao Artemisia annua (Asteraceae) Artemisinin and its derivatives Holy thistle Cnicus benedictus (Asteraceae) Cnicin Cinnamon Cinnamomum zeylanicum b-caryophyllene (Lauraceae) Cloves Syzygium aromaticum b-caryophyllene (Myrtaceae) Hop Humulus lupulus (Cannabaceae) Humulene Wormseed Artemisia cinia (Asteraceae) a-santonin Valerian Valeriana officinalis Valeranone (Valerianaceae) Juniper berries Juniperus communis a-cadinene (Cupressaceae) Curcuma or Cucuma longa Curcumenone, curcumabranol turmeric (Zingiberaceae) A, curcumabranol B, b-elemene, curzerenone 6. One of the simplest and most significant of the diterpenes is phytol, a reduced form of geranylgeraniol, which constitutes the lipophilic side-chain of the chlorophylls. Vitamin A is also a 20-carbon-containing compound, and can be regarded as a diterpene. Among the medicinally important diterpenes, paclitaxel, isolated from Taxus brevifolia (family Taxaceae), is one of the most successful anticancer drugs of modern time. The following table presents just a few of these sources, and their major diterpenoidal components. Two molecules of farnesyl pyrophosphate are joined tail-to-tail to yield squalene. The conformation that all-trans-squalene 2,3-epoxide adopts, when the initial cyclization takes place, determines the stereochemistry of the ring junctions in the resulting triterpenoids. The initially formed cation intermediate may undergo a series of 1,2-hydride and methyl migrations, commonly called backbone rearrangements, to provide a variety of skeletal types. For example, fusidic acid is an antimicrobial fungal metabolite, isolated from Fusidium coccineum, and cytotoxic dimeric triterpenoids, crellastatins, are isolated from marine sponges Crella species. Within these cyclic triterpe- noids distinct structural variations lead to several structural classes of triterpenoids. The following table presents just a few of these sources, and their major triterpenoidal components. Source Major diterpenes Common name Botanical name (Family) Fusidium Fusidium coccineum Fusidic acid Ganoderma Ganoderma lucidum Lanosterol Dammar resin Balanocarpus heimii Dammarenediols (Dipterocarpaceae) Ginseng Panax ginseng (Araliaceae) Dammarenediols Lupin Lupinus luteus (Fabaceae) Lupeol Quillaia Quillaja saponaria (Rosaceae) Quillaic acid 6. Chemistry of vision: role of vitamin A b-carotene is converted to vitamin A1 (retinol) in our liver. It is oxidized to an aldehyde called all-trans-retinal, and then isomerized to produce 11-cis-retinal, which is the light-sensitive pigment present in the visual systems of all living beings. Rod and cone cells are the light sensitive receptor cells in the retina of the human eye. About three million rod cells are responsible for our vision in dim light, whereas the hundred million cone cells are responsible for our vision in the bright light and for the perception of bright colours. This cis–trans isomerization is accompanied by an alteration in molecular geometry, which generates a nerve impulse to be sent to the brain, resulting in the perception of vision. Well, all these drugs and many other important drugs belong to the class of compounds called steroids. They are synthesized in glands and delivered by the bloodstream to target tissues to stimulate or inhibit some process. Their nonpolar character allows them to cross cell membranes, so they can leave the cells in which they are synthesized and enter their target cells. Hundreds of distinct steroids have been identified in plants, animals and fungi, and most of them have interesting biological activity. They have a common basic ring structures, three-fused cyclohexane rings, together the phenanthrene part, fused to a cyclopentane ring system, known as cyclopentaphenanthrene. The four rings are lettered A, B, C and D, and the carbon atoms are numbered beginning in the A ring as shown in gonane. Androstane Pregnane Cholane A C19 steroid A C21 steroid A C steroid 24 Many steroids have an alcoholic hydroxyl attached to the ring system, and are known as sterols. There are many different steroid hormones, and cholesterol is the precursor for all of them. Barton of Great Britain received the Nobel Prize in 1969 for recognizing that functional groups could vary in reactivity depending on whether they occupied an axial or an equatorial position on a ring (see Chapter 3). All three of the six- membered rings can adopt strain-free chair conformations as shown below. Unlike simple cyclohexane rings, which can undergo chair–chair interconver- sions, steroids, being the large rigid molecules cannot undergo ring-flips. Steroids can have either cis or trans fusion of the A and B rings; both kind of steroid are relatively long, flat molecules but the A, B trans-fused steroids are by far the more common, though cis-fused steroids are found in bile. Furthermore, the presence of two angular methyl groups at C-10 and C-13 positions is characteristic in cholesterol. Substituents on the steroid ring system may be either axial or equatorial, and as usual equatorial substitution is more favourable than axial substitution for steric reasons. Thus, the hydroxyl group at C-3 of cholesterol has the more stable equatorial orientation. The lower side of the steroid is denoted a, the upper side of the steroid is denoted b, usually drawn as projected below the plane of the paper, which is shown as broken lines, and above the plane of the paper, which is drawn as solid lines. Cholesterol has eight chiral centres, therefore 256 stereoisomers are theoretically possible, but only one exists in nature! Stereogenic centres in steroid side chains are denoted preferentially with the R and S nomenclature. However, with the increase in number of hydroxyl or other polar functional groups on the steroid skeleton, the solubility in polar solvents increases. Glucocorti- coids are a class of steroid hormones characterized by an ability to bind with the cortisol receptor and trigger similar effects. Glucocorticoids regulate many aspects of metabolism and immune functions, and are 6. Rather than a head-to-tail arrangement of six units of isoprene, there appear to be farnesyl units that have been connected tail to tail. Cholesterol is biosynthesized from squalene, which is first converted to lanosterol. The conversion of squalene to the steroid skeleton is an oxirane, squalene-2,3-oxide, which is trans- formed by enzymes into lanosterol, a steroid alcohol naturally found in wool fat. Squalene is an important biological precursor of many triterpenoids, one of which is cholesterol. The first step in the conversion of squalene to lanosterol is epoxidation of the 2,3-double bond of squalene. Acid-catalysed ring opening of the epoxide initiates a series of cyclizations, resulting in the formation of protesterol cation. Elimination of a C-9 proton leads to the 1,2- hydride and 1,2-methyl shifts, resulting in the formation of lanosterol, which in turn converted to cholesterol by enzymes in a series of 19 steps. The pill is an oral contraceptive containing synthetic derivatives of the female sex hormones, progesterone and oestrogen. The two most important birth-control pills are norethindrone and ethynyloestradiol. Many synthetic steroids have been found to be much more potent than natural steroids.
The most reactive dienophiles usually have a carbonyl group generic betnovate 20gm online acne 9 weeks pregnant, but it may also have another electron- withdrawing group purchase 20gm betnovate visa acne qui se deplace et candidose, e betnovate 20gm on line skin care di jakarta. For example, 1,3-butadiene reacts with maleic anhydride to produce tetrahy- drophthalic anhydride on heating. O H O 1 Benzene + O O 4 Heat O H O 1, 3-Butadiene Maleic anhydride Tetrahydrophthalic anhydride A conjugated diene A dienophile 95% 5. Compounds contain- ing carbon–carbon triple bonds can be utilized as dienophiles to produce compounds with two bonds as shown below. A bridged bicyclic compound contains two rings that share two nonadjacent carbons. Essential structural features for dienes and dienophiles In the Diels–Alder reaction, the conjugated diene can be cyclic or acyclic, and it may contain different types of substituent. A conjugated diene can exist in two different conformations, an s-cis and an s-trans. In the Diels–Alder reaction, the conjugated diene has to be in an s-cis conformation. A conjugated diene that is perma- nently in an s-trans conformation cannot undergo this reaction. This s-cis feature must also be present in conjugated cyclic dienes for Diels– Alder reaction. In fact, cyclopentadiene is reactive both as a diene and as a dienophile, and forms dicyclopentadiene at room temperature. When dicyclopentadiene is heated to 170 C, a reverse Diels–Alder reaction takes place and reforms the cyclopentadiene. Room H temperature + = 170 oC Diene Dienophile H Dicyclopentadiene Stereochemistry of Diels–Alder reaction The Diels–Alder reaction is stereospecific. For example, freshly distilled cyclopentadiene, having s-cis configuration, reacts with maleic anhydride to give cis-norbornene-5,6-endo-dicarboxylic anhydride. O o H 0 C + O O Few minutes H O O O Cyclopentadiene Maleic anhydride cis-norbornene-5,6- endo-dicarboxylic anhydride There are two possible configurations, endo and exo, for bridged bicyclic compounds resulting from the reaction of a cyclic diene and cyclic dienophile. A substituent on a bridge is endo if it is closer to the longer of the two other bridges, and it is exo if it is closer to the shorter bridge. However, if this reaction is reversible, and thermodynamically controlled, the exo pro- duct is formed. In this rearrangement reaction, a s bond is broken in the reactant and a new s bond is formed in the product, and the p bonds rearrange. Sigmatropic reactions are usually uncatalysed, although Lewis acid catalysts are sometimes used. Sigmatropic rearrangement plays an important role in the biosynthesis of vitamin D in our bodies. O Heat O Bond broken New bond formed This reaction can occur through hydrogen shift, alkyl shift (Cope rearrange- ment) or Claisen rearrangement. Hydrogen shift A sigmatropic rearrangement involves the migration of a s bond from one position to another with a simultaneous shift of the p bonds. Antarafacial means that opposite faces are involved, whereas it is suprafacial when both changes occur at the same face. Many sigmatropic rearrangements and Diels–Alder reactions can be either suprafacial or antarafacial and this dictates the stereo- chemistry. Antarafacial hydrogen shifts are observed in the conversion of lumisterol to vitamin D. H H H H H H H 200 oC H H H (Z)-1,3-pentadiene (Z)-1,3-pentadiene Alkyl shift: Cope rearrangement In addition to the migration of hydrogen atoms in sigmatropic rearrange- ments, alkyl shifts also take place. More specifically, these reactions involve methyl shifts at 4n+3 positions in a suprafacial fashion with inversion of stereochemistry. As [3,3] sigmatropic rearrangements involve three pairs of electrons, they take place by a suprafacial pathway under thermal conditions. Ph Ph Heat Claisen rearrangement Sigmatropic rearrangements involving the cleavage of a s bond at an oxygen atom are called Claisen rearrangement. A Claisen rearrangement is a [3,3] sigmatropic rearrangement of an allyl vinyl ether to produce a g, d-unsaturated carbonyl compound. Like Cope rearrangement, this reaction also forms a six-membered ring transition state. This reaction is exothermic and occurs by a suprafacial pathway under thermal conditions. Ph Ph O Heat O Claisen rearrangement plays an important part in the biosynthesis of several natural products. For example, the chorismate ion is rearranged to the prephenate ion by the Claisen rearrangement, which is catalysed by the enzyme chorismate mutase. This prephenate ion is a key intermediate in the shikimic acid pathway for the biosynthesis of phenylalanine, tyrosine and many other biologically important natural products. However, in practice, the term natural product refers to secondary metabolites, small molecules (molecular weight < 1500 amu), produced by an organism, but not strictly necessary for the survival of the organism. Chemistry for Pharmacy Students Satyajit D Sarker and Lutfun Nahar # 2007 John Wiley & Sons, Ltd. Natural products have been an integral part of the ancient traditional medicine systems, e. Even now, continuous traditions of natural product therapy exist throughout the third world, especially in the orient, where numerous minerals, animal substances and plants are still in common use. This represents about 88 per cent of the world’s inhabitants, who rely mainly on traditional medicine for their primary health care. Over the last century, a number of top selling drugs have been developed from natural products. Anticancer drug vincristine from Vinca rosea, narcotic analgesic morphine from Papaver somniferum, antimalarial drug artemisinin 1 from Artemisia annua, anticancer drug Taxol from Taxus brevifolia and antibiotic penicillins from Penicillium ssp. Time and time again, humans have turned to Mother Nature for cures, and discovered unique drug molecules. Thus, the term natural product has become almost synonymous with the concept of drug discovery. In modern drug discovery and development processes, natural products play an important role at the early stage of ‘lead’ discovery, i. It is estimated that 61 per cent of the 877 small molecule new chemical entities introduced as drugs worldwide during 1981–2002 can be traced back to or were developed from natural products. These include natural products (6 per cent), natural product derivatives (27 per cent), synthetic compounds with natural-product-derived pharmacophores (5 per cent) and synthetic com- pounds designed on the basis of knowledge gained from a natural product, i. In some therapeutic areas, the contribution of natural products is even greater, e. In 2000, approximately 60 per cent of all drugs in clinical trials for the multiplicity of cancers were of natural origins. Despite the outstanding record and statistics regarding the success of natural products in drug discovery, ‘natural product drug discovery’ has been neglected by many big pharmaceutical companies in the recent past. The declining popularity of natural products as a source of new drugs began in the 1990s, because of some practical factors, e. Complexity in the chemistry of natural products, especially in the case of novel structural types, also became the rate-limiting step in drug discovery programmes.
Providing this information in a nonthreatening manner may help to eliminate these undesirable behaviors cost of betnovate acne jeans men. Help client identify situations that provoke defensiveness and practice through role-play more appropriate responses order betnovate 20gm acne fulminans. Role-playing provides confidence to deal with difficult situ- ations when they actually occur buy cheap betnovate 20 gm skin care laser clinic birmingham. Positive feedback enhances self-esteem and encourages repetition of desirable behaviors. Help client set realistic, concrete goals and determine appropriate actions to meet those goals. With client, evaluate the effectiveness of the new behaviors and discuss any modifications for improvement. Because of limited problem-solving ability, assistance may be required to reassess and develop new strategies in the event that some new coping methods prove ineffective. Client verbalizes correlation between feelings of inadequacy and the need to defend the ego through rationalization and grandiosity. Client interacts with others in group situations without taking a defensive stance. Long-term Goal Client will be able to interact with staff and peers, by the time of discharge from treatment, with no indication of discomfort. Be honest; keep all promises; convey acceptance of the person, separate from Disorders Usually First Diagnosed in Infancy, Childhood, or Adolescence ● 35 unacceptable behaviors (“It is not you, but your behavior, that is unacceptable. Positive feedback enhances self-esteem and encourages repetition of desirable behaviors. Confront client and withdraw attention when interactions with others are manipulative or exploitative. Act as a role model for client through appropriate interac- tions with other clients and staff members. It is through these group interactions that client will learn socially acceptable behavior, with positive and negative feedback from his or her peers. Client has formed and satisfactorily maintained one inter- personal relationship with another client. Client verbalizes reasons for past inability to form close interpersonal relationships. Long-term Goal By discharge from treatment, client will develop, and use, age- appropriate, socially acceptable coping skills. If client is hyperactive, make environment safe for continuous large-muscle movement. Nurse may join in some of these activities to facilitate relationship development. Provide frequent, nutritious snacks that client may “eat on the run,” to ensure adequate calories to offset client’s exces- sive use of energy. Say, “I understand why you are saying these things (or doing these things) and I will not tolerate these behaviors from you. Client may try to play one staff member against another, so consistency is vital if intervention is to be successful. Caution should be taken to avoid reinforcing manipulative behaviors by providing desired attention. Attention provides positive reinforcement and encourages repetition of the undesirable behavior. Confront client’s use of manipulative behaviors and explore their damaging effects on interpersonal relationships. Dealing with the feelings honestly and directly will discourage displacement of the anger onto others. Explore with client alternative ways of handling frustration that would be most suited to his or her lifestyle. Provide sup- port and positive feedback to client as new coping strategies are tried. Client is able to delay gratification, without resorting to ma- nipulation of others. Client is able to verbalize alternative, socially acceptable, and lifestyle-appropriate coping skills he or she plans to use in response to frustration. Long-term Goal By time of discharge from treatment, client will exhibit increased feelings of self-worth as evidenced by verbal expression of positive aspects about self, past accomplishments, and future prospects. It is important for client to achieve something, so plan for activities in which the pos- sibility for success is likely. Commu- nication of your acceptance of him or her as a worthwhile human being increases self-esteem. Assist client in identifying positive aspects of self and in developing plans for changing the characteristics he or she views as negative. Give positive reinforcement for problem identification and development of more adaptive coping behaviors. Positive reinforcement enhances self-esteem and increases client’s use of acceptable behaviors. Encourage and support client in confronting the fear of fail- ure by having client attend therapy activities and undertake new tasks. Offer recognition of successful endeavors and positive reinforcement for attempts made. It is an alerting signal that warns of im- pending danger and enables the individual to take measures to deal with threat. Possible Etiologies (“related to”) Situational and maturational crises Threat to self-concept [perceived or real] Threat of death Unmet needs [Fear of failure] [Dysfunctional family system] [Unsatisfactory parent–child relationship] [Innately, easily agitated temperament since birth] Defining Characteristics (“evidenced by”) Overexcited Fearful Feelings of inadequacy Fear of unspecified consequences Restlessness Insomnia Poor eye contact Focus on self [Continuous attention-seeking behaviors] Difficulty concentrating Impaired attention Increased respiration and pulse Goals/Objectives Short-term Goals 1. Within 7 days, client will be able to verbalize behaviors that become evident as anxiety starts to rise. Within 7 days, client will be able to verbalize strategies to interrupt escalation of anxiety. Long-term Goal By time of discharge from treatment, client will be able to main- tain anxiety below the moderate level as evidenced by absence of disabling behaviors in response to stress. Honesty, availability, and acceptance promote trust in the nurse–client relationship. Provide activities geared toward reduction of tension and decreasing anxiety (walking or jogging, volleyball, musical exercises, housekeeping chores, group games). Tension and anxiety are released safely and with benefit to client through physical activities. Encourage client to identify true feelings, and to acknowl- edge ownership of those feelings. Anxious clients often deny a relationship between emotional problems and their anxi- ety. Nurse must maintain an atmosphere of calmness; anxiety is easily transmitted from one person to another. However, nurse must be cautious with its use, because anxiety may foster suspicion in some individuals who might misinterpret touch as aggression. As anxiety diminishes, assist client to recognize specific events that preceded its onset.
Total body hydration is normally maintained with continuous low-volume crystalloid infusion (e generic betnovate 20 gm on line acne 10 dpo. Fluid charts may be divided between colloids (colloidal infusions against blood loss) and crystalloids (crystalloid infusion against urine output) purchase betnovate 20gm overnight delivery acne killer. Blood is often transfused if haemoglobin falls below 10 g/dl (haematocrit below 33 per cent) 20gm betnovate visa skin care lab. Haemodilution with colloids usually necessitates blood supplements, and so patients should already have units crossmatched. Temperature Gradual rewarming should bring central temperature within 2°C of peripheral (pedal) temperature (avoid limbs from which saphenous veins are harvested). Use of artificial warming is controversial: it can cause burns, although recently marketed warming devices are generally safe and reliable; it hastens homeostasis and may prevent shivering (which increases metabolic rate, so increasing oxygen consumption and metabolic acidosis). Acid-base balance Anaerobic metabolism from cold cardioplegia and hypoperfusion causes metabolic acidosis so that cardiovascular instability continues during rewarming. Although acidosis is closely monitored through blood gas analysis, it is not usually necessary to treat acidosis following cardiac surgery. Dysrhythmias Various dysrhythmias (often multifocal) often occur following cardiac (especially valve) surgery. Causes include: ■ chronic cardiomyopathy ■ oedema (from surgery, disrupting conduction pathways) ■ acidosis ■ electrolyte imbalance ■ hypoxia/ischaemia ■ mechanical irritation (e. Atrial fibrillation, the most common postoperative dysrhythmia (Ellis 1998), is relatively benign. Bradycardia, blocks, functional and tachydysrhymias frequently occur; persistent blocks often require pacing, hence perioperative placement of epicardial wires. Intensive care nursing 300 Epicardial wires are unipolar, a negative pole being created by inserting a subcutaneous needle. Pacing wires usually remain in place until dysrhythmias become unlikely (normally 5–10 days). Internal defibrillation avoids transthoracic bioimpedance, so uses lower voltage (e. Causes include: ■ fluid shifts from vasoactive mediators ■ hyperkalaemia from damaged cell membranes leakage ■ hypokalaemia from forced diuresis; also cell recovery returning potassium to intracellular fluid ■ hormones (e. Hyperkalaemia may necessitate insulin and dextrose infusion (which can cause later rebound hyperkalaemia). Supplementary diuretics may be used, but some patients later require haemofiltration (see Chapter 35). Prolonged peri- and postoperative hypotension can precipitate acute tubular necrosis. Renal protection with dopamine is increasingly being replaced by dobutamine or dopexamine (see Chapter 32). Pain control Pain control is central to intensive care nursing; absence of pain is desirable for both humanitarian and physiological reasons (see Chapter 7); poor pain control may prolong recovery, circulating catecholamines impairing myocardial perfusion. Early postoperative pain usually needs opiate infusion, possibly supplemented by nonsteroidal anti- inflammatories. Although Kuperberg and Grubbs (1997) found patients were satisfied with their analgesia, many studies (e. Valdix & Puntillo 1995; Cottle 1997) suggest postoperative pain control remains poor with nurses underestimating pain (Ferguson et al. Pain is individual and so should be individually assessed rather than stereotyped by the operations performed. Since thoracic nociceptor innervation is relatively sparse, patients often experience relatively less pain from thoracic incisions than from saphenous incisions, although arterial graft spasm (e. Saphenous vein harvest necessitates a long incision, stimulating many nociceptors, thus causing considerable pain (Horvath et al. Types of pain experienced following cardiac surgery include: ■ bone pain (sharp/throbbing) ■ visceral pain ■ muscle pain (harvest site) ■ cardiac/angina pain ■ neurogenic pain ■ psychogenic pain (anxiety) Patterns may be: ■ continuous ■ sudden/spasm Continuous analgesia may alleviate underlying/continuous pain (including anxiety- related pain), but nurses should observe for breakthrough (usually spasm) pain. Sedation, a valuable adjunct to promote comfort, is usually limited to a few hours, and so rapidly cleared drugs (e. Neurological complications Potentially fatal thrombi (and emboli) may be from ■ cardiopulmonary bypass ■ air emboli ■ thrombotic vegetations (chronic preoperative atrial fibrillation). Neurological deficits can cause ■ impaired peripheral nerve function ■ cerebral/cognitive deficits ■ uncontrollable hypertension (injury to vital centres). Neurological assessment is a priority, but cerebrovascular accidents may remain undetected until patients show deficits or fail to wake normally. Postoperatively, mood is often labile, euphoria (induced by opiates and survival) being followed (day 2–4) by reactive depression. Stress provokes tachycardia, hypertension and hyperglycaemia (see Chapter 3), all impairing recovery in patients least able to tolerate such insults. Providing information, achieving optimum pain control, relieving anxieties and minimising sensory imbalance are therefore important aspects of holistic nursing care. Skin care Wound breakdown or skin ulceration may occur from (Waterlow 1996; Lewicki et al. On regaining consciousness, pain and anxiety often make patients reluctant to move. Sternal instability can cause ‘clicking’ sounds; although not painful, external stabilisation with hands or a cushion helps deep breathing and coughing. Wound dressings are usually removed within 24 hours, and then left exposed unless oozing. Perfusion of graft sites (especially radial artery grafts; also arteriovenous shunts) should be protected, and so pressure (e. Normalisation Nurses can experience considerable satisfaction from assisting rapid postoperative recovery following cardiac surgery. Normalisation should be urged, and families and friends encouraged to visit, as they would on a surgical ward. Cardiac surgery 303 Early mobilisation should be supported, musculoskeletal complications and pulmonary emboli being the main causes of delayed discharge (Johnson & McMahan 1997). Transplantation issues The severing of the sympathetic and parasympathetic pathways causes loss of vagal tone, resulting in resting rates of about 100 beats/minute (Adam & Osborne 1997). Denervation also (usually) prevents angina, increasing risk of silent infarction (12 per cent of patients do experience pain (Tsui & Large 1998)). A loss of sympathetic tone impairs cardiac response to increased metabolic demands, making atropine ineffective (Adam & Osborne 1997). Surgery preserves recipients’ right atrium, resulting in two P waves (one intrinsic, one graft) (Adam & Osborne 1997). Although not pathologically significant, the reasons for the presence of two P waves should be explained to patients, families and junior nurses. Many possible postoperative complications result from the necessities of intraoperative procedures; increasing percutaneous surgery may significantly reduce numbers of open heart operations. Clinical scenario Peter Da Silver is a 48-year-old man with a history of angina, hypertension and insulin dependent diabetes. Review causative factors for this complication and propose a plan of care to stabilise sternum, promote healing and recovery (evaluate various treatment approaches, pharmacological/surgical interventions, equipment used to stabilise sternum, appropriate nutrition). Haemostasis has four phases: ■ smooth muscle contraction (vasoconstriction; myogenic reflex) ■ formation of platelet plugs ■ formation of fibrin clot (blood clotting/coagulation), followed by retraction of fibrin clots ■ fibrinolysis.
