By Y. Aschnu. Lynchburg College.
If a systemic hypersensitivity reaction occurs discount 160 mg kamagra super overnight delivery, enfuvirtide should be discontinued and never used again purchase 160mg kamagra super. Identifying High-Risk Patients Patients with elevated liver function and cardiovascular disease must be monitored carefully cheap kamagra super 160mg overnight delivery. P a t i e n t E d u c a t i o n Maraviroc Advise patients that discount kamagra super 160 mg without a prescription, if they forget to take a dose, they should take the missed dose as soon as possible and take the next scheduled dose at its regular time. If the time to the next dose is less than 6 hours, the patient should skip the missed dose and take the next dose as scheduled. Inform patients about signs of an evolving reaction (itchy rash, yellow skin, dark urine, and vomiting and/or abdominal pain) and instruct them to stop maraviroc and seek medical attention. Liver injury has been seen in some patients and may be preceded by evidence of an allergic reaction. During clinical trials, a few patients experienced cardiovascular events, including myocardial ischemia and myocardial infarction. P a t i e n t E d u c a t i o n Raltegravir Inform patients about signs of a hypersensitivity reaction (e. Raltegravir can cause potentially fatal hypersensitivity reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. The treatment recommendations presented in this chapter reflect those guidelines, which are available at http://www. Infection is frequently asymptomatic in women and may also be asymptomatic in men. Treatment Adults and Adolescents For uncomplicated urethral, cervical, or rectal infections in adults or adolescents, treatment with either azithromycin [Zithromax] or doxycycline [Vibramycin, others] is recommended. Patients who are unable to take these medications may take erythromycin, levofloxacin [Levaquin], or ofloxacin [generic]. If the patient cannot take azithromycin, the approved alternatives are amoxicillin, erythromycin base, or erythromycin ethylsuccinate. Conjunctivitis does not result in blindness and spontaneously resolves in 6 months. The preferred treatment for both infections is oral erythromycin base or erythromycin ethylsuccinate. Although topical erythromycin, tetracycline, or silver nitrate may be given to prevent conjunctivitis, these drugs are not completely effective—and they have no effect on pneumonia. Preadolescent Children Although infection in preadolescent children can result from perinatal transmission, sexual abuse is the more likely cause, especially in children older than 2 years. For children who weigh less than 45 kg, the preferred treatment is oral erythromycin base or erythromycin ethylsuccinate. For children who weigh 45 kg or more, but are younger than 8 years, the preferred treatment is azithromycin. For children at least 8 years old, the preferred treatments are azithromycin or doxycycline. From this site, the organism migrates to regional lymph nodes, causing swelling, tenderness, and blockage of lymphatic flow. Erythromycin base serves as an alternative for those who cannot take tetracycline antibiotics. Gonococcal Infections Characteristics Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative diplococcus, often referred to as the gonococcus. In men, the main symptoms are a burning sensation during urination and a pus-like discharge from the penis. In contrast, gonorrhea in women is often asymptomatic or may present as mild cervicitis. However, serious infection of female reproductive structures (vagina, urethra, cervix, ovaries, fallopian tubes) can occur, ultimately resulting in sterility. Among people who engage in oral sex, the mouth and throat can become infected, causing sore throat and tonsillitis. Among people who engage in receptive anal sex, the rectum can become infected, causing a purulent discharge and constant urge to move the bowels (tenesmus). Bacteremia can develop in males and females, causing cutaneous lesions, arthritis, and, rarely, meningitis and endocarditis. Treatment Owing to antibiotic resistance, treatment of gonorrhea has changed over the years—and undoubtedly will continue to evolve. In the 1930s, virtually all strains of the gonococcus were sensitive to sulfonamides. Fortunately, by that time penicillin had become available, and the drug was active against all gonococcal strains. This recommendation was changed yet again in 2012, also triggered by antimicrobial resistance—this time to oral cephalosporins. If a patient is allergic to azithromycin, a 7-day course of doxycycline may be substituted. Spectinomycin, an aminoglycoside, has also been suggested; however, it is not currently available in the United States. Pharyngeal Infection Gonococcal infection of the pharynx is more difficult to treat than infection of the urethra, cervix, or rectum; therefore, parenteral therapy is recommended for all patients. Azithromycin is preferred over doxycycline because patients are more likely to adhere to a single-dose regimen of azithromycin than the full-week regimen of doxycycline taken twice a day. Conjunctivitis Gonococcal conjunctivitis can be reliably eradicated with ceftriaxone plus azithromycin. Symptoms include petechial or pustular skin lesions, arthritis, arthralgia, and tenosynovitis. Neonatal Infection Neonatal gonococcal infection is acquired through contact with infected cervical exudates during delivery. To protect against neonatal ophthalmia, a topical antibiotic should be instilled into both eyes immediately postpartum—as required by law in most states. If this antimicrobial is not available, parenteral therapy with ceftriaxone is to be used. Possible manifestations include sepsis, arthritis, meningitis, and scalp abscesses. Preadolescent Children Among preadolescent children, the most common cause of gonococcal infection is sexual abuse. For children with localized infection who weigh more than 45 kg, treatment is the same as for adults. Other likely agents are Ureaplasma urealyticum, Trichomonas vaginalis, and Mycoplasma genitalium. The recommended treatment is either azithromycin [Zithromax] or doxycycline [Vibramycin]. Alternative regimens are erythromycin base, erythromycin ethylsuccinate, levofloxacin, or ofloxacin. Azithromycin should be added to the regimen if it had not been used during initial therapy. Unfortunately, we have no easy tests for this bacterium, and hence definitive diagnosis may not be possible. However, Mycoplasma hominis, as well as assorted anaerobic and facultative bacteria, may also be present. This may be attributable to intensified patient education efforts, increased and improved screening practices, or improved adherence to single- dose treatment. Because multiple organisms are likely to be involved, drug therapy must provide broad coverage. For the hospitalized patient, treatment can be initiated with either cefoxitin or cefotetan, combined with doxycycline. The syndrome occurs primarily in young adults (under 35 years old) and may be associated with urethritis. Primary symptoms are fever accompanied by pain in the back of the testicles that develops over the course of several hours. For patients with gonococcal or chlamydial infection, the recommended treatment is ceftriaxone [Rocephin] plus doxycycline [Vibramycin, others]. For patients who engage in insertive anal sex, the addition of levofloxacin or ofloxacin is recommended to target enteric bacteria. Non–sexually transmitted epididymitis generally occurs in older men and in men who have had urinary tract instrumentation. Characteristics Syphilis develops in three stages, termed primary, secondary, and tertiary. After an incubation period of 1 to 4 weeks, a primary lesion, called a chancre, develops at the site of entry. Skin lesions and flu-like symptoms (fever, headache, reduced appetite, general malaise) are typical. The symptoms of secondary syphilis resolve in 4 to 8 weeks—but may recur episodically over the next 3 to 4 years. Infection of the brain—neurosyphilis—is common and can cause senility, paralysis, and severe psychiatric symptoms. Early signs of congenital syphilis include sores, rhinitis, and severe tenderness over bones. However, instead of receiving a single dose, adults and children receive three doses 1 week apart. Syphilis in pregnancy should be treated with penicillin G, using a dosage appropriate to the stage of the disease. For nonpregnant patients with early or late syphilis, either doxycycline or tetracycline may be used. For patients with neurosyphilis, ceftriaxone can be effective, but possible cross-reactivity with penicillin is a concern. Bacterial Vaginosis Bacterial vaginosis is a common vaginal infection in women of childbearing age. Organisms responsible for the syndrome include Gardnerella vaginalis (also known as Haemophilus vaginalis), Mycoplasma hominis, and various anaerobes. The syndrome occurs most commonly in sexually active women, although it may be transmitted in other ways. Bacterial vaginosis is characterized by a malodorous vaginal discharge, elevation of vaginal pH (above 4. Clue cells (epithelial cells whose borders are obscured by bacteria) are typically found on microscopic examination of vaginal secretions. The recommended therapy for bacterial vaginosis is either oral or vaginal metronidazole [Flagyl] or vaginal clindamycin cream. Clindamycin cream is available as a short-acting 2% clindamycin cream [Cleocin] and a long-acting 2% clindamycin cream [Clindesse]. Clindesse cream is formulated to adhere to the vaginal mucosa for several days and hence can clear bacterial vaginosis with just one application. Approved alternative regimens are tinidazole [Tindamax], oral clindamycin, or clindamycin ovules (intravaginal suppositories). Unlike the other drugs approved for bacterial vaginosis, tinidazole should not be prescribed for pregnant women. In women, infection may be asymptomatic or may cause a diffuse, malodorous, yellow-green vaginal discharge, along with burning and itching.
Diabetic ketoacidosis can also occur • Insulin increases glucose uptake by muscle and fat buy discount kamagra super 160mg online, in individuals with type 2 diabetes generic 160mg kamagra super overnight delivery, particularly those who decreases hepatic glucose output purchase 160 mg kamagra super, and controls post- are hospitalized for other medical or surgical conditions purchase kamagra super 160mg without prescription. Therapy must be individualized, based on the clinical and • Type 1 diabetes is typically treated with a long-acting laboratory status of the patient. Intravenous fuids are given insulin to meet basal insulin requirements and a rapid- to restore fuid volume that has been depleted by osmotic acting insulin at mealtimes to control postprandial diuresis and vomiting. Alternatively, an insulin pump can be used of insulin is given to decrease the plasma glucose concentra- to provide basal and mealtime injections of insulin. Intravenous adminis- • Insulin lispro, insulin aspart, and insulin glulisine are tration of potassium chloride is usually required to rapid-acting insulin preparations. Insulin glargine and counteract hypokalemia that results from the correction of insulin detemir are used as long-acting insulins. Dextrose (glucose) should be • Other antidiabetic drugs include hypoglycemic agents added to the intravenous infusion when glucose levels fall to (sulfonylureas and meglitinides) and antihyperglycemic 250 mg/dL, because hyperglycemia is usually corrected agents (α-glucosidase inhibitors, metformin, and more rapidly than is acidosis. Insulin should be continued thiazolidinediones, incretin mimetics, and an amylin until acidosis is resolved and the plasma bicarbonate level is analogue). Hypoglyce- Treatment of type 2 diabetes rests on a foundation of a mia is the main side effect of these drugs. Dietary recommen- • Acarbose and miglitol inhibit α-glucosidase and slow dations should attempt to limit calories and saturated fat. Overweight patients should be encouraged to exercise and • Metformin, pioglitazone, and rosiglitazone decrease lose weight to improve glycemic control, reduce insulin hepatic glucose output and increase insulin sensitivity resistance, and lower plasma lipid levels. Met- trations exceeding 7%, the next step is usually to add an oral formin can be used alone or in combination with most antidiabetic medication. The meglitinide drugs such as repaglinide are taken 30 minutes before meals to control postprandial glycemia in review Questions individuals with type 2 diabetes. Meglitinide drugs increase before each meal and must eat at that time to prevent insulin secretion in the same manner as sulfonylureas by hypoglycemia. This leads to closing of potassium channels, (A) closing of potassium channels membrane depolarization, and insulin secretion. B, (B) slowed gastric emptying slowed gastric emptying, is caused by an amylin analogue (C) inhibition of α-glucosidase (pramlintide) and by incretin mimetics such as exenatide. At mealtimes, a patient with type 1 diabetes injects both produced by sitagliptin. E, insertion of glucose transport- insulin and a drug that slows gastric emptying. Which ers in cell membranes, may result from pioglitazone adverse effect may result from this drug? Pramlintide is an (B) nausea and anorexia amylin analogue that slows gastric emptying and the (C) fatulence and bloating delivery of carbohydrates to the intestines. It is used in (D) weight gain individuals with type 1 or type 2 diabetes who take (E) increased risk of heart failure insulin, and its side effects include nausea, vomiting, and 3. The answer is D: insertion of glucose transporters in (A) increased insulin secretion adipose tissue. Which structural modifcation is found in this insulin Insulin glargine is formulated as a solution that forms analogue? It con- (A) addition of a 14-carbon fatty acid chain tains a glycine substitution and the addition of two (B) transposition of proline and lysine arginine residues to the terminal amino acid of native (C) substitution of aspartate for another amino acid insulin. Metformin increases insulin acids sensitivity and, unlike many other antidiabetic drugs, it (E) addition of two arginine residues may result in loss of weight. A woman is placed on a drug that increases insulin sen- effect of metformin is diarrhea. It does not increase risk sitivity and typically results in a loss of body weight. This decreases the extracellular phosphate concentration, which in turn tends to increase the Calcium and Vitamin D extracellular calcium concentration. The physiologic signifcance of calcitonin is unclear, • Teriparatide (Forteo) because normal calcium balance is maintained in the absence • Cinacalcet (Sensipar) of calcitonin in persons who undergo thyroidectomy. Other Agents The recruitment and activation of osteoclasts are mediated • Calcitonin (Calcimar, Miacalcin) by compounds released from osteoblasts and peripheral leu- • Raloxifene (Evista) kocytes called bone cell cytokines. The cytokines include • Strontium ranelate (Protelos) interleukins, tumor necrosis factor, colony-stimulating • Sodium fuoride factors, and other factors that alter gene expression. After a the osteoclasts are activated, they adhere to the bone surface Also ergocalciferol (vitamin D2) and calcitriol (Calcijex, Rocaltrol). The destroyed bone releases growth factors that increase osteoblast production and decrease osteoclast activ- ity. The entire remodeling process takes The strength and structure of bone result from the deposition about 100 days on average. Normal bone is constantly undergoing remodeling by The balance between bone resorption and bone forma- sequential demineralization and mineralization. During tion is usually maintained until the third or fourth decade remodeling, bone calcium is in dynamic equilibrium with of life, when a slow, age-related imbalance begins and favors ionized calcium in extracellular fuid. Hormonal and nutritional def- ization increases as the extracellular calcium concentration ciencies can contribute to this imbalance. The proper extracellular calcium concentration is also required for normal Bone Disorders function of nerves and muscles, gland secretion, blood coagu- Osteoporosis, the most common bone disorder, is charac- lation, enzyme activities, and other physiologic functions. Vertebral fractures are the most fre- Control of the extracellular calcium concentration depends quent type of fracture in patients with postmenopausal on hormonal regulation of the absorption and excretion of osteoporosis, a disorder partly caused by decreased estrogen calcium, as well as on the exchange of ionized calcium with secretion in this population; hip, humerus, and pelvis frac- bone. As shown in Figure 36-1, the hormones involved in tures are also major causes of immobility, morbidity, and this regulation include vitamin D, parathyroid hormone mortality in older persons. Pregnant and nursing 1000-1300 600 *Food and Nutrition Board, Institute of Medicine of the National Academies. She recently Osteomalacia is characterized by abnormal mineraliza- entered menopause and for the past 3 months has been tion of new bone matrix. The condition has numerous taking a low dose of oral estrogen and a vaginal estrogen causes, the most common of which include vitamin D def- cream along with cyclic medroxyprogesterone to relieve menopausal symptoms. The treatment has reduced hot ciency, abnormal vitamin D metabolism, phosphate def- fashes and sleep disruption, but she still has an occasional ciency, and osteoblast dysfunction. Because her mother had osteoporosis and frac- usually results from vitamin D defciency and is called tured her hip, the woman asks about preventive therapy. This disorder is uncommon today because of vitamin She has been taking an adequate amount of calcium and D–supplemented foods and sun exposure. Based on fere with vitamin D absorption, metabolism, or target organ her T-score and family history of osteoporosis, her physician response and result in osteomalacia. All persons should be encouraged by health goes a sharp decline, and the risk of fractures increases with professionals to meet the recommendations of the Institute age. The risk factors of vitamin D3 and 1200 mg of calcium were found to have include a previous fragility fracture, a family history of frac- an increased bone density and a decreased incidence of ture, cigarette smoking, and low body weight (<127 hip and nonvertebral fractures in comparison with those pounds). In another study, administration tive treatment, and a bisphosphonate drug is usually of vitamin D3 was found to decrease the incidence of verte- selected for this purpose. Diet and vitamin supplements also provide vitamin D3, which is activated by specifc hydroxylation steps in the liver and kidneys to form 1,25-dihydroxyvitamin D3 (calcitriol). The absorption of In the United States, it is estimated that two thirds of calcium carbonate requires stomach acid, whereas the women age 18 and over have an inadequate calcium intake, absorption of calcium citrate does not. In addition to their role in the prevention high-calcium dairy product would provide about 1200 mg and treatment of osteoporosis, calcium and vitamin D are and thereby fulfll the daily requirement for all adults and also the primary treatment for hypocalcemia. Even with ingesting adequate amounts of adverse effect of calcium supplements is constipation. This vitamin D, only about 30% of calcium is absorbed from milk is best managed by ingesting adequate amounts of fruits and other dairy products, and calcium absorption from and vegetables. In the Calcitonin frst phase, growth factors induce circulating preosteo- Estrogen Plicamycin + clasts to differentiate to osteoclasts and attach to bone. For example, there is evidence is the most active form of the vitamin in the human body. D3 at the 25 position in the liver to form calcifediol Adverse Effects and Interactions. Vitamin D preparations are used for the fol- and barbiturates can induce enzymes that metabolize lowing purposes: (1) to ensure adequate vitamin D intake to vitamin D and lead to vitamin D defciency. Hence persons prevent rickets and to develop and maintain suffcient bone taking these drugs often require vitamin D supplementa- mass and strength to prevent osteoporosis, (2) to treat tion and may beneft from determination of serum vitamin vitamin D–dependent rickets, familial hypophosphatemia D levels. Patients with chronic renal failure Most of the drugs used in treating bone disorders inhibit must be treated with calcitriol because they lack the bone resorption by osteoclasts. These agents include the 1α-hydroxylase enzyme required to synthesize the active bisphosphonate drugs, calcitonin, estrogen and raloxifene, form of vitamin D (see Fig. In contrast, teriparatide stimulates bone Many vitamin D preparations are available for admini- formation by osteoblasts. Most of these prepa- mechanism, acting to inhibit bone resorption while increas- rations contain vitamin D3 (cholecalciferol), vitamin D2 ing bone formation. The bisphosphonate compounds A number of bisphosphonate compounds are available to produce varying degrees of gastrointestinal distress. The original bisphosphonate, eti- Alendronate and risedronate seldom cause gastric distress dronate, is the least potent inhibitor of bone resorption. Clinical trials have phonates, such as alendronate, pamidronate, risedronate, shown that long-term use of bisphosphonates (usually over and tiludronate, are about 100-fold more potent than eti- 5 years) increases the risk of atypical femur fractures called dronate, and third-generation drugs, such as ibandronate subtrochanteric femur fractures and diaphyseal femur frac- and zoledronic acid, are almost 1000-fold more potent than tures, which occur just below the hip joint or in the long etidronate. Most patients Chemistry and Pharmacokinetics who develop these fractures experience a dull, aching pain Bisphosphonate drugs are pyrophosphate analogues in in the thigh or groin for weeks or months before a fracture which the phosphorus-oxygen-phosphorus structure (P – O occurs. Pamidronate and zoledronic acid are given intravenously, but Finally, bisphosphonates may increase the risk of osteone- other bisphosphonates are administered orally and ibandro- crosis of the jaw, especially in persons with poor oral health nate can be given orally or intravenously. Hence patients are advised to take bisphosphonates with a Calcium supplements and antacids decrease the absorption full glass of water 30 minutes before ingesting anything else of bisphosphonates and should be taken at least 2 hours in the morning. Once absorbed, about half of the drug is before or after a bisphosphonate compound. The bisphosphonates adsorb to hydroxyapatite and Specifc Drugs become a permanent part of the bone structure. They are Alendronate was the frst bisphosphonate to be approved slowly released from bone during bone remodeling, and the for the treatment of osteoporosis, and it appears to be effec- terminal half-life appears to be greater than 10 years. Clinical trials in women with Mechanisms and Pharmacologic Effects postmenopausal osteoporosis indicate that alendronate pre- Bisphosphonates prevent bone resorption by inhibiting vents bone loss and produces a sustained increase in bone osteoclast activity. A study of women with low bone mass and preexisting ably the prevention of the attachment of osteoclasts to bone. For example, available in oral formulations for once-daily or once-weekly tiludronate decreases tyrosine phosphatase activity in osteo- administration. Tiludronate treatment also reduces activity of the prevention and treatment of osteoporosis in postmeno- proton pump by which osteoclasts secrete hydrogen ions that pausal women. Risedronate formulations are available for daily, weekly, twice-monthly, Indications and monthly administration. Bisphosphonate compounds are used in the management of Alendronate, pamidronate, risedronate, and tiludro- a variety of disorders, including osteoporosis, Paget disease nate are approved for the treatment of Paget disease of of bone, hypercalcemia, and osteolytic bone lesions of bone. As discussed later, the various com- usually show evidence of increased bone turnover (remodel- pounds have different uses.
Inspiratory to expiratory cycling—the start of expiration expiration starts when a preset value of fow purchase 160 mg kamagra super with amex, time discount kamagra super 160mg with amex, volume (or pressure) is reached quality 160mg kamagra super. Pressure cycling is now only used as a safety backup for other forms of cycling buy discount kamagra super 160mg on-line, i. Mandatory vs spontaneous and patient-ventilator synchrony Mandatory breaths are machine triggered or cycled. In an active patient, patient ventilator interaction during expiration is the same. During the second (trigger) window, patient efort will trigger a time-cycled mandatory breath. Patient eforts are allowed, and superimposed on the time-cycled inspiratory pressure. Difculties include inspiratory trigger delay, inefective triggering, double triggering, auto triggering, inspiratory time extension, early expiratory cycling, and failure of expiratory cycling. Complications encountered in mechanical ventilation Complications of endotracheal tube • Ventilator-associated pneumonia • tracheal stenosis • Vocal cord injury • tracheo-oesophageal fstula • Sinusitis. Both changes in lung volume and changes in intrathoracic pressure con- tribute to these consequences. Potential benefts of positive intrathoracic pressure • Alveolar recruitment: • Reduced shunt • i V/Q. Detrimental heart lung interactions can be minimized by preventing both hyperinfation and alveolar derecruitment, reducing work of breathing, pre- venting volume overload during weaning, and avoiding negative pressure swings in intrathoracic pressure during spontaneous breathing. It increases FrC, recruits alveoli, reduces shunt, helps prevent atelectrauma and reduces preload and afterload. A full discussion of the best way to set the level of PeeP is out with the scope of this chapter. Ventilator Induced Lung Injury this term encompasses barotrauma (injury due to excessive pressure) and volutrauma (injury due to excessive volume) – in combination these pro- duce alveolar strain (defned as the ratio between the amount of gas volume delivered compared with the amount of aerated lung receiving it). Acknowledgement this section is adapted from Anaesthesia & Intensive Care Medicine, 4, 0, Martin hughes et al. It will improve oxy- genation, increase minute ventilation, and usually reduce work of breathing. Cardiogenic pulmonary oedema i lung water secondary to interstitial and alveolar oedema increases the elastic workload of the lung and reduces compliance. Use of non-invasive ventilation to wean critically ill adults of invasive ventilation: meta-analysis and systematic review. Noninvasive ventilation in exacerbations of chronic obstructive pulmonary dis- ease: implications of diferent meta-analytic strategies. Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease. It need not be a prolonged process, and many patients are weaned immediately postoperatively. Unnecessary prolongation of ventilation is costly and associated with an i risk of ventilator-associated pneumonia, lung injury, and delirium. Titration of respiratory support A process of active weaning is diferent from the titration of respiratory support while the wean screen (see later in topic) excludes the patient from a spontaneous breathing trial. Consider both the support required for oxygenation, and the support required for work of breathing. Inspiratory pressures, on the other hand, are reduced as tidal volume improves with i compliance, and if work of breathing is reasonable. Assessment of suitability for weaning Prediction of successful weaning has been the subject of much investiga- tion. Unfortunately, the likelihood ratios are not large enough to make these measurements a real alternative to spontaneous breathing trials. If the wean screen is passed, a spontaneous breathing trial is undertaken and suitability for extubation (see b extubation, p. Wean screen • Adequate resolution of underlying disease • Pao2/Fio2 > 25kPa, PeeP ≤8cmh2o • Low-dose inotropic or vasoconstrictor support • Capable of spontaneous breaths. Spontaneous breathing trials Spontaneous breathing trials do not take account of the preconditions to extubation (see b extubation, p. After a prolonged weaning process, progressively increasing the dura- tion of the trial until the trial lasts ≥24 hours may be appropriate. Despite a reluctance to use such protocols, in trials they outperform or match more traditional methods of weaning. Management of weaning failure Identify factors which increase respiratory load or decrease respiratory capacity. It allows accurate assessment of lung parenchyma and pleural disease: • exclude infection. Cardiovascular • If echocardiography is normal, repeat during a spontaneous breathing trial. Chapter 27 287 Circulatory support Pharmacological support 288 Mechanical circulatory support: extracorporeal life support 294 288 ChaPter 27 Circulatory support Pharmacological support there is a lack of robust clinical evidence demonstrating a positive impact on survival concerning the use of vasoactive agents. Inotropic agents Catecholamines Catecholamines exert their cardiovascular efects via activity at specifc adr- energic (a, β, β2) and dopaminergic (D) receptors. Sensitive β receptor efects are evident at low plasma concentrations while α efects become more prominent at higher concentrations. Clinical indications • Pulmonary hypertension and/or rV dysfunction with potential reversibility, e. Clinical use • Initial dose: 20ppm, with subsequent reduction to achieve minimum efective dose (usually –5ppm). Where recovery or transplantation is not anticipated in a period of 28 days but is likely to occur, a long-term VaD may be used. Contraindications • Severe aortic regurgitation • Severe calcifc aorto-iliac disease and/or peripheral vascular disease • Disease of the descending aorta (aortic coarctation or aneurysm) • Sheathless insertion in severe obesity. Despite this anticoagulation with unfractionated heparin is required which must be carefully monitored by frequent activated partial thromboplastin times (aPtts). Treatment strategy • Bridge to decision • Bridge to recovery • Bridge to bridge (long-term device) • Bridge to transplantation. Indications • Dilated cardiomyopathy: • Ischaemic • Myocarditis • Peripartum • Post cardiotomy • Congenital heart disease • Primary graft failure post cardiac transplantation. Worldwide as the survival on VaDs has improved, the use of long-term VaDs for destination therapy has i. Complications were common and tended to be infection, bleeding or thromboembolic related. Risks and complications • air embolism • Bleeding • thrombotic risk • Stroke • Ischaemic limbs • haemolysis • Infection • Immobility. Cannulation is by percutaneous cannulation of a major vein (internal jugu- lar and/or femoral) with fuoroscopic (or tOe) guidance. Indications are ventilator refractory respiratory failure with predominant hypercapnia and respiratory acidosis. Some patients need it for longer and there may be an eventual need for a permanent pacemaker due to com- plications of surgery. The majority of patients never require pacing and it is difcult to predict which patients may need pacing. So, most surgeons implant ventricular wires (at least one) in all patients while some do so only when patients required pacing immediately prior to chest closure. Should a patient with a single ventricular wire require pacing a wire is placed under the skin and the pacing circuit completed by attaching the ventricular wire to the negative terminal of the pacing box. Also, when atrial wires are avoided to decrease possible complications when need for pacing is predicted to be of short duration or to suppress ectopic beats with overdrive pacing. There is a risk of ventricular tracking of atrial tachyarrhythmias which is of-set by setting a ‘maximum tracking rate’. The cardiac rate is captured by pac- ing at 20% of the intrinsic rate and then gradually reduced, establishing stable sinus rhythm. Manoeuvres which may be helpful: • Increasing pacemaker output • Correction of exacerbating factors listed earlier • reversing polarity of bipolar pacing wires • Changing to unipolar pacing with subcutaneous return pacing wire • Temporary transvenous or oesophageal pacing if threshold progressively increasing • Transcutaneous pacing in an emergency. Failure to sense This must be distinguished from normal pacemaker function with inappro- priate settings. Cross-talk This occurs in dual-chamber pacing modes when the atrial pacing spike is sensed by the ventricular wire and inhibits ventricular output. Stimulation threshold checked in all patients and sensing threshold once an intrinsic rhythm has been established. The underlying rhythm should be checked regularly by turning down the pacing rate and letting the endog- enous rhythm to emerge, thereby assessing ongoing need for pacing. Stimulation threshold This is the minimum output (mA) needed to consistently capture the heart. Sensing threshold This is the least sensitive setting (biggest mV value) at which the pacemaker can detect a heartbeat. Temporary epicardial pacing after cardiac surgery: a practical review: Part : General considerations in the management of epicardial pacing. Temporary epicardial pacing after cardiac surgery: a practical review: Part 2: Selection of epicardial pacing modes and troubleshooting. Chapter 29 313 Sedation and pain relief Introduction 34 Patient assessment 35 Pharmacology 37 Clinical protocols 39 314 ChaPter 29 Sedation and pain relief Introduction after cardiac surgery, patients require a short period of sedation or symp- tom control to minimize oxygen consumption while they re-establish their normal physiology. Patients after minimally invasive and of-pump procedures can be consid- ered for early extubation but still have to be supported with a satisfactory analgesic protocol. Principles of sedation We must diferentiate short-term sedation in the uncomplicated patient from long-term sedation in unstable patients who develop critical illness. Principles of pain relief experience of postoperative pain is often complex and multifactorial. Modern con- cepts of postoperative analgesia are based on • Multimodal approaches including local anaesthetics • Favourable pharmacokinetics and pharmacodynamics • Good ability to titrate to patient’s requirements • No or minimal adjustments in patients with organ dysfunction • Pharmaco-economics. It is based on a com- bined assessment of the mental status beyond the infuence of pharmaco- logical sedation. Normally used as an -point scale with 0=no pain and 0 (00) represent- ing the worst imaginable pain. Optimizing patient recovery this includes faster achievement of recovery goals such as extubation and mobilization, but also allows more efective physiological and functional recovery, e. Further reading haenggi M, Ypparila-Wolters h, hauser K, Caviezel C, takala J, Korhonen I, et al. Most drugs work synergistically when used together, so lower doses/concentrations of each component is advisable. Opioids Morphine Popular and efective opioid that also has sedative characteristics. Mainly used intravenously by nurse-controlled boluses or patient-controlled anal- gesia. Unsuitable for long-term exposure due to high variability in pharmaco- dynamics and metabolism. Shallow dose–response curve allows it to be used in spontaneously breathing patients. Remifentanil Ultra-short-acting fentanyl congener with context-sensitive half-time of only 3–4 minutes.
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