By S. Rakus. Central Washington University.
It is not advisable to continue with surgery whilst she is fully anticoagulated as she is likely to bleed excessively buy genuine suhagra on line, so a method of stopping it temporarily must be found effective suhagra 100 mg. The best option is to switch to heparin 100mg suhagra, which can be stopped and restarted more easily purchase suhagra 100mg fast delivery, with the possibility of staying on heparin until the histology report is available and you know whether she is going to need major surgery such as a hysterectomy for cancer in the near future. She has had four children between the ages of 6 months and 4 years, all delivered by caesarean section using a Pfannenstiel incision. The nurses are concerned because she has abdominal pain and she is still not well enough to go home, although your consultant saw her last night after the operating list had ﬁnished and discharged her. When you examine her you notice some watery discharge from her suprapubic incision, which is soaking through the dressing. If you have assisted in theatre, you will know that a Pfannenstiel incision involves opening the peritoneum as far as the umbilicus, so it possible to have bowel stuck to the back of the scar all the way up the anterior abdominal wall, even if the skin incision is suprapubic. As a caesarean incision heals, it is not unusual for the bladder to become adherent – to the front of the uterus and to the back of the abdominal incision – so it is possible that the second port for the sterilisation has gone through the bladder. We know that bowel damage at laparoscopy is not always recognised at the time of injury and that the presentation is often delayed so that the patient has returned home by the time she develops symptoms of peritonitis. She has had an uncomplicated evacuation of uterus performed, but the clinical notes mention that she did have a coughing ﬁt as she was being anaesthetised. You are not sure at this stage whether she is having an exacerba- tion of her asthma, has a pneumothorax, or has aspirated. F Endocervical chlamydia swab Although most patients undergoing minor gynaecological procedures will have haemoglobin estimation this is not necessary unless they have heavy periods. For this patient it is more important to check that she does not have an undiagnosed chlamydia infection as dye laparoscopy may result in a further episode of acute pelvic infammatory disease. Another distracter here is pregnancy test but she is day 8 of the cycle so this is not relevant. Your consultant is trying to decide whether to remove the uterus and other ovary as well as the diseased ovary. If there is any suspicion of malignancy the correct operation is total hysterectomy, bilateral salpingo-oophorectomy, and omentectomy for staging of the disease. She has been using a copper coil for contraception but you cannot see the strings and she thinks it was extruded from the uterus during an unusually heavy period 4 weeks ago. K Pregnancy test You might want to do a haemoglobin level in view of the recent heavy period but the main worry here is that she has not had contraceptive protection for the last few weeks giving her a chance to conceive prior to being sterilised. J Urea and electrolytes As she has no bowel sounds, the diagnosis is paralytic ileus. You do not really need an abdominal x-ray to diagnose this – just use your stethoscope – but it can be associated with a low potassium level therefore the U&E is more use than an x-ray in the management of this patient because it will help you decide which intravenous fuids to prescribe. On examination you ﬁnd an inspiratory wheeze but normal air entry all over the chest. You should be able to locate it on an abdominal flm (although an ultrasound of the uterus would also be useful but we haven’t given you this option). The persistent ileus could be due to urine in the peritoneal cavity as a result of ureteric damage during surgery and the consequences of missing that diagnosis are potentially much more serious, with loss of renal function on the affected side. On readmission she is pyrexial and bimanual pelvic examination reveals a palpable tender mass at the vault with offensive brown blood in the vagina. E High vaginal swab Although a haemoglobin level would be routine here, you already know that she is anaemic and is being treated for it. You will be prescribing antibiotics for this patient anyway but the point of a high vaginal swab is to check that the treatment is correct depending on the sensitivities. A A guardian with power of attorney should sign the consent form B Consent from the patient is valid C Defer the operation until a court order can be obtained D Defer the operation until an independent interpreter is available E Defer the operation until the woman is fully recovered F Operate without consent in the patient’s best interest G The consent already given is no longer valid H The woman has a right to refuse consent 130 09:33:45. She needs a hysteroscopy to investigate the problem but cannot understand what is being proposed. A guardian with power of attorney should sign the consent form It is clearly in the best interests of this patient for her to have the investigation done especially as the bleeding has made her anaemic. In the absence of family, it is likely that she will have a legal guardian who could sign the consent form for her. In fact, the ‘consent form’ is form 4, which is a statement of why the procedure is in her best interests and ideally the legal guardian would sign in agreement to the procedure. She has a needle phobia and adamantly refuses caesarean sec- tion to deliver the baby quickly. Both the obstetric consultant and the pae- diatrician have explained the possible consequences to her. The woman has a right to refuse consent Although the consequences of this woman’s decision could have profound effects on her baby’s health, the baby has no rights in law until it is born. It is her right to refuse consent, and the responsibility of the health professionals involved is to ensure that her decision is fully informed. You might need to take into account the effects of any drugs she might have had for pain relief in labour and take care to document fully everything that is explained to her. She speciﬁcally states that she will not accept blood transfusion and signs a disclaimer form preoperatively. In the recovery room it becomes apparent that she has internal bleeding and the consultant decides to take her back to theatre. Operate without consent in the patient’s best interest The blood transfusion issue is not relevant to consent in this situation but the longer the return to theatre is delayed, the more likely she is to die. The surgeon can take her back to theatre urgently to stop the bleeding without further consent especially as she will not accept blood transfusion. Although it has not been discussed previously with the patient, the midwife mentions the possibility of the patient being asked to participate in the research project. The woman should not be asked to participate in the research It is not appropriate to take consent for participation in a research project in an emergency situation. There is no time available for the woman to consider the options and either participate or withdraw consent if she wants to and these things are best discussed earlier in pregnancy. She will not tell her parents about the pregnancy and after much discussion she is thought to be able to understand the risks of the procedure. Consent from the patient is valid If the teenager is deemed to be competent to understand the implications of her decision (so-called Fraser competence), then she can give consent for the proce- dure. It is always best if she does tell her parents (especially if she develops a com- plication) and we would always encourage her to think about doing that. She had a hysteroscopy done under local anaesthetic for irreg- ular heavy bleeding recently but the histology on the endometrium from that operation is not yet available. F Postpone the operation and arrange urgent gynaecology clinic review The original symptoms may be caused by endometrial cancer, so irregular peri- menopausal bleeding should be dealt with urgently (in the same way as post- menopausal bleeding). You need to check the histology before she has her uterus removed as hysterectomy for endometrial cancer is a different operation from that for benign disease (e. She was put on the waiting list for an ovarian cystectomy but her symptoms have now disappeared. She mentions a family history of ‘difﬁculty waking up’ after anaesthetics but is not sure of the clinical details. H Postpone the operation until you can arrange further tests This patient may have inherited suxamethonium apnoea and it is possible to test for this. Even though she wants a spinal anaesthetic, this may not give enough analgesia on the day of surgery and the anaesthetist will want to know that it is safe to give her a general anaesthetic. A Cancel the operation as it is not the correct procedure for this patient This patient is obviously unaware that endometrial ablation is not a suitable oper- ation if pregnancy is desired in the future. The operation is designed to remove the endometrial layers right down to the basal layer that regenerates each cycle. Pregnancy has been reported after this operation but it is not usually successful and we often recommend that patients considering this are sterilised concurrently. You look up the results before signing her consent form for a laparoscopy and dye test only to discover that the chlamydia swab is positive. D Postpone the operation and arrange review in genito-urinary medicine clinic It is inadvisable to proceed with her surgery until the chlamydia infection has been adequately treated and contact tracing has been done – which is the main reason for involving the genito-urinary medicine clinic. She has gradually become more breathless over the previous 24 hours and now seems a little con- fused. She is hypoxic and expresses discomfort when you ask for deep breaths to auscultate her chest but there is normal air entry. Her tempera- ture is normal and you do not see any abnormality on her chest x-ray. G Pulmonary embolus The hypoxia and chest pain on inspiration suggest either a chest infection, pulmonary embolism, or pneumothorax. There is a moderate amount of old blood coming from the vagina and her haemoglo- bin has dropped from 127 g/l preoperatively to 82 g/l now.
By blocking muscarinic receptors in the eyes purchase suhagra on line amex, atropine can cause mydriasis and paralysis of the ciliary muscle order suhagra canada. The ophthalmic uses of atropine and other muscarinic antagonists are discussed in Chapter 84 suhagra 100 mg online. Heart rate is increased because blockade of cardiac muscarinic receptors reverses parasympathetic slowing of the heart cheap suhagra 100mg mastercard. By blocking muscarinic receptors in the intestine, atropine can decrease both the tone and motility of intestinal smooth muscle. This can be beneficial in conditions characterized by excessive intestinal motility, such as mild dysentery and diverticulitis. When taken for these disorders, atropine can reduce both the frequency of bowel movements and associated abdominal cramps. Atropine is a specific antidote to poisoning by agents that activate muscarinic receptors. By blocking muscarinic receptors, atropine can reverse all signs of muscarinic poisoning. An atropine autoinjector (Atropen) is approved for use in people exposed to the irreversible cholinesterase inhibitor nerve agents or insecticides discussed previously. The AtroPen should be used immediately on exposure or if exposure is strongly suspected. Injections are administered into the lateral thigh, directly through clothing if necessary. If symptoms are mild, one dose should be given; if severe symptoms develop afterward, additional doses can be given up to a maximum of three doses. Because it can suppress secretion of gastric acid, atropine has been used to treat peptic ulcer disease. Unfortunately, when administered in doses that are strong enough to block the muscarinic receptors that regulate secretion of gastric acid, atropine also blocks most other muscarinic receptors. Therefore use of atropine in treatment of ulcers is associated with a broad range of antimuscarinic side effects (dry mouth, blurred vision, urinary retention, constipation, and so on). Because of these side effects, atropine is not a first-choice drug for ulcer therapy. Rather, atropine is reserved for rare cases in which symptoms cannot be relieved with preferred medications (e. By blocking bronchial muscarinic receptors, atropine can promote bronchial dilation, thereby improving respiration in patients with asthma. Unfortunately, in addition to dilating the bronchi, atropine also causes drying and thickening of bronchial secretions, effects that can be harmful to patients with asthma. Furthermore, when given in the doses needed to dilate the bronchi, atropine causes a variety of antimuscarinic side effects. Because of the potential for harm, and because superior medicines are available, atropine is rarely used for asthma. Biliary colic is characterized by intense abdominal pain brought on by passage of a gallstone through the bile duct. In some cases, atropine may be combined with analgesics such as morphine to relax biliary tract smooth muscle, thereby helping alleviate discomfort. Adverse Effects Most adverse effects of atropine and other anticholinergic drugs are the direct result of muscarinic receptor blockade. Accordingly, these effects can be predicted from your knowledge of muscarinic receptor function. Blockade of muscarinic receptors on salivary glands can inhibit salivation, thereby causing dry mouth. Not only is this uncomfortable, it also can impede swallowing and can promote tooth decay, gum problems, and oral infections. Patients should be informed that dryness can be alleviated by sipping fluids, chewing specially formulated sugar-free gum (e. Owing to increased risk for tooth decay, patients should avoid sugary gum and hard candy. Blockade of muscarinic receptors on the ciliary muscle and the sphincter of the iris can paralyze these muscles. Paralysis of the ciliary muscle focuses the eye for far vision, causing nearby objects to appear blurred. Patients should be forewarned about this effect and advised to avoid hazardous activities if vision is impaired. Additionally, paralysis of the iris sphincter prevents constriction of the pupil, thereby rendering the eye unable to adapt to bright light. In addition, these drugs should be used with caution in patients who may not have glaucoma per se but for whom a predisposition to glaucoma may be present. Blockade of muscarinic receptors in the urinary tract reduces pressure within the bladder and increases the tone of the urinary sphincter and trigone. In the event of severe urinary retention, catheterization or treatment with a muscarinic agonist (e. Patients should be advised that urinary retention can be minimized by voiding just before taking their medication. Patients should be informed that constipation can be minimized by increasing dietary fiber, fluids, and physical activity. Because of their ability to decrease smooth muscle tone, muscarinic antagonists are contraindicated for patients with intestinal atony, a condition in which intestinal tone is already low. Blockade of muscarinic receptors on sweat glands can produce anhidrosis (a deficiency or absence of sweat). Because sweating is necessary for cooling, people who cannot sweat are at risk for hyperthermia. Patients should be warned of this possibility and advised to avoid activities that might lead to overheating (e. Blockade of cardiac muscarinic receptors eliminates parasympathetic influence on the heart. By removing the “braking” influence of parasympathetic nerves, anticholinergic agents can cause tachycardia. In patients with asthma, antimuscarinic drugs can cause thickening and drying of bronchial secretions and can thereby cause bronchial plugging. Consequently, although muscarinic antagonists can be used to treat asthma, they can also do harm. A number of drugs that are not classified as muscarinic antagonists can nonetheless produce significant muscarinic blockade. Among these are antihistamines, phenothiazine antipsychotics, and tricyclic antidepressants. Because of their prominent anticholinergic actions, these drugs can greatly enhance the antimuscarinic effects of atropine and related agents. Accordingly, it is wise to avoid combined use of atropine with other drugs that can cause muscarinic blockade. In most cases, urge incontinence results from involuntary contractions of the bladder detrusor (the smooth muscle component of the bladder wall). These contractions are often referred to as detrusor instability or detrusor overactivity. Urge incontinence should not be confused with stress incontinence, defined as involuntary urine leakage caused by activities (e. Among people ages 40 to 44 years, symptoms are reported by 3% of men and 9% of women. In comparison, among those 75 years and older, symptoms are reported by 42% of men and 31% of women. Behavioral therapy, which is at least as effective as drug therapy and lacks side effects, should be tried first. Behavioral interventions include scheduled voiding, timing fluid intake, doing Kegel exercises (to strengthen pelvic floor muscles), and avoiding caffeine, a diuretic that may also increase detrusor activity. If behavioral therapy and drugs are inadequate, a provider may offer specialized treatments (e. These drugs block muscarinic receptors on the bladder detrusor and thereby inhibit bladder contractions and the urge to void. Unfortunately, drugs that block muscarinic receptors in the bladder can also block muscarinic receptors elsewhere and cause the typical anticholinergic side effects previously described.
The onset of menses (menarche) is the final event of puberty order suhagra with amex, occur- ring approximately 2 cheap suhagra 100 mg with mastercard. N ormal puberty takes place between the ages of 8 and 14 years buy suhagra 100mg without a prescription, with an average duration of 4 discount 100mg suhagra free shipping. Delayed puberty is the absence of secondary sexual characteristics by the age of 14 years. Thelarche → Adrenarche→ Growth spurt → Menarche Breast bud → Axillary and pubic hair → Menses Delayed puberty can be subdivided on the basis of two factors: the gonado- tropic and the gonadal state. T hese individuals have an abnormalit y in, or t he absence of one of t he X chromosomes leading to gonadal dysgenesis and a 45,X karyotype. T hus, they lack ovarian est rogen product ion and, as a result, secondary sexual characterist ics. The internal and external genit alia are t hat of a normal woman, but remain infant ile even int o adult life. O t h er ch aract erist ic physical fin d in gs are sh or t st at u r e, webbed n eck, low set ear s an d p ost er ior h air lin e, wid ely spaced nipples or “sh ield chest,” and increased carrying angle at t he elbow. Turner syndrome should be suspect ed in an individual who present s wit h primary amen- orrhea, prepubescent secondary sexual characteristics, and sexually infantile ext ernal genit alia. Other causes of hypergonado- tropic hypogonadism are ovarian damage due to exposure to ionizing radiation, chemot herapy, inflammat ion, or t orsion. H ypothalamic dysfunction may occur due to poor nutri- tion or eating disorders (anorexia nervosa and bulimia), extremes in exercise, and ch r on ic illn ess or st r ess. O t h er cau ses are pr imar y h yp ot h yr oid ism, Cu sh in g syn - drome, pituitary adenomas, and craniopharyngiomas (the most commonly associ- ated neoplasm). The diagnostic approach to delayed puberty begins with a meticulous history and physical examinat ion. The history should query chronic illnesses, exercise and eat ing habit s, and age of menarche of t he pat ient ’s sist ers and mot her. The physical examinat ion should search for signs of chronic illness, such as a goit er, or neu- rologic deficits, such as visual field defects indicative of cranial neoplasms. The management goals for those with delayed puberty are to initiate and sus- tain sexual maturation, prevent osteoporosis from hypoestrogenemia, and promote the full height potential. Hormonal therapy and human growth hormone can be used to achieve these objectives. Patients with hypergonadotropic hypogonad- ism presenting with delayed puberty should be started on unopposed est rogen for 2 to 3 years before a progestin is added. They are started on low-dose estrogen and then gradually increased every 3 months. Exposure to progestins during the fir st 2 t o 3 year s of est rogen t h er apy would lead t o abn or mal d evelopment of the breasts (tubular breast format ion). O nce the breast s are formed and are at Tanner st age 3 or 4, a progest in is added. Combinat ion of oral cont racept ives provides t he adequate amount of est rogen needed to prevent osteoporosis, and t he progest in protects against endometrial cancer. Patients with hypogonadotropic hypogonadism with no apparent cause need imaging of t he brain to rule out a brain tumor. In n on -t r eat able con dit ion s su ch as gon ad al dysgen esis, est r ogen r eplace- ment is started then followed with combination estrogen/ progestin therapy. Pre co cio u s Pu b e r t y O n the other end of the spectrum, girls who develop secondary sexual character- ist ics t oo early are said t o have precocious pubert y. In general, t he definit ion is breast development prior to age 7, and in African-American women, prior to age 6. Cent ral causes can in clu d e br ain t u mor s, men in git is, h ydr oceph alu s, or h ead t r au ma. Per iph er al cau ses can in clu d e gr anu losa cell t u mor s of the ovar y, M cCu n e-Albr igh t syn d r om e, or adrenal tumors. If precocious puberty is untreated, the girl will be taller than her peers init ially, but due t o early long bone epiphyseal closure, t he eventual height will be short er. The patient’s mother notes that both of patient’s sisters had onset of breast development at age 10, and also all of her friends have already begun menstruating. Examination reveals Tanner stage I breast and pubic/ axillary hair, and is otherwise unremarkable. D evelo p m en t is wit h in n o r m al lim it s an d sh o u ld b e o b ser ved C. Which of the following laborat or y findings is likely t o be elevat ed in this pat ient? Breast tissue usually is infantile (Tanner stage I) with gonadal dysgenesis because no estrogen is produced; these patients are at risk for osteoporo- sis. Delayed puberty is defined as no secondary sexual characteristics by the age of 14 years. Primary amenorrhea is defined as no menarche by the age of 16 years in the presence of secondary sexual characteristics, or age 14 in the absence of secondary sexual characterist ics. This dist in guish es ovarian failure from a central nervous system dysfunction (central defect). Estrogen and progesterone levels are low; the prolactin, and thyroxin levels remain unchanged. H ad the patient had a karyotype similar to that in Turner syn- drome (45,X), another gonadal dysgenesis disorder, a gonadectomy on the st reak ovaries, would not be indicat ed. Interest ingly, only hypothyroidism causes precocious puberty with delayed bone age. All other et iologies of precocious pubert y are associat ed wit h accelerated bone age (bone age“older”than chronological age). The patient’s mother recalls a doctor mentioning that her daughter had a missing right kidney on an abdominal x-ray film. Most likely finding on pelvic examination: Blin d vagin al p ou ch or vagin al d imple. Know the definition of primary amenorrhea, that is, no menses by the age of 16 years. Know that the two most common causes of primary amenorrhea when there is normal breast development are müllerian agenesis and androgen insensitivity. Understand that a serum testosterone level or karyotype would differentiate the two conditions. Co n s i d e r a t i o n s This 18-year-old adolescent woman has never had a menstrual period; therefore, she has primary amenorrhea. Breast development con n ot es the pres- ence of est rogen, and axillary and pubic hair suggest s t he presence of androgens. The most likely diagnosis is müllerian agenesis because a significant fract ion of such pat ient s will have a urinary t ract abnormalit y. Also, wit h androgen insensit ivit y, t h ere is t ypically scant axillary and pubic hair since there is a defective androgen receptor. The diagnosis can be con- fir m ed wit h a ser u m t est ost er on e, wh ich would be n or mal in mü ller ian agen esis, and elevated (in t he normal male range) in androgen insensit ivit y. In both condi- tions, there is no uterus, tubes, or cervix, and a blind vaginal pouch or vaginal dimple. N otably, absence of breast development would point to a hypoestrogenic state such as gonadal dys- genesis ( Turner syndrome). After pregnancy is excluded, t he t wo most common etiologies that cause primary amenorrhea associated with normal breast development and an absent uterus are androgen insensitivity syndrome and müllerian agenesis (Table 55– 1). H owever, due to a defect in the andro- gen receptor synthesis or action, there is no formation of male internal or external gen it alia. T h e ext er n al gen it alia r em ain fem ale, as it occu r s in the absen ce of sex st eroids. T h ere are no int ernal female reproduct ive organs, and t he vagina is short or absent. W ithout androgenic opposition to the small circulating levels of estro- gen secr et ed by the gon ad s an d ad r en als, an d pr odu ced by p er iph er al conver sion of androstenedione, breast development is normal or enhanced. The abnormal int ra-abdominal gonads are at increased risk for malig- nancy, but this rarely occurs before puberty. After these events take place, usually around the age of 16 to 18 years, the gonads should be removed. The diagnosis of androgen insensitivity syndrome should be suspected when a pat ient has primary amenorrhea, an absent uterus, nor- mal breast development, an d scant or absent pubic and axillary hair. T h e diagn osis can be con fir m ed wit h a kar yot yp e evalu at ion an d/ or elevat ed t est ost er on e levels (male normal range).
In patients having mechanical ventilation order suhagra 100 mg with visa, the rate of induction or depth of anesthesia can be adjusted by changing the respi- Thalamus ratory rate or tidal volume purchase suhagra 100 mg free shipping. A history reveals that he was backpacking in the country and was fed some wild replaced older buy cheap suhagra on line, volatile liquid anesthetics (e buy 100mg suhagra with mastercard. The halogenated drugs have ness and pain in the lower abdomen, which is worse after a more rapid rate of induction and recovery, cause a much the physician presses down and quickly removes his hand. After the surgery, he respiratory and cardiovascular functions are monitored develops a fever, severe muscle rigidity and contractions, during the use of halogenated anesthetics, and artifcial ven- and tachycardia. The anesthesiologist recognizes that he tilation and circulatory support are often required. The halo- has a case of malignant hyperthermia and administers genated anesthetics cause uterine relaxation, which usually dantrolene. Because halogenated anesthetics produce relatively Appendicitis is infammation of the appendix, a small pocket little analgesia or skeletal muscle relaxation, they are often off the large intestine that is commonly thought of as a given in combination with nitrous oxide, opioids, muscle vestigial organ but recently has been suggested to play a relaxants, and other adjunct drugs in what is called balanced role as a reservoir for intestinal fora and to serve an immune anesthesia. When treated promptly by appendectomy, most Halothane is the prototypical halogenated anesthetic, patients with acute appendicitis recover without diffculty, and desfurane, enfurane, isofurane, and sevofurane are but if treatment is delayed, the appendix can burst, causing newer halogenated anesthetics. Many cases of appendicitis are linked inhalational agent, but it has several disadvantages. Because to a blockage in the lumen of the organ and can be caused by impacted feces or even a fruit pit. Malignant hyperther- of its relatively high blood : gas partition coeffcient, its rate mia is associated with over 80 genetic defects and appears of induction and recovery is slower than that of other halo- to be inherited with an autosomal dominant inheritance genated anesthetics. Most defects are related to mutations of the ryano- cholamines more than other anesthetics do, it places patients dine receptor located on intracellular organelles, such as the at greater risk for cardiac dysrhythmias. Hence, the use sarcoplasmic reticulum, which mediate the release of Ca2+ of epinephrine for hemostasis must be strictly limited in from these intracellular stores. Halothane undergoes appre- intravenous route, binds to the ryanodine receptor, and ciable hepatic metabolism and is converted to reactive inter- blocks the release of Ca2+ and the resultant sequelae that mediate metabolites that can produce a hypersensitivity characterize malignant hyperthermia. For this reason, a patient who is anesthetized with halothane should not be reexposed has occurred; as a result, methoxyfurane was recently with- to it for 6 to 12 months. They undergo less Nonhalogenated Drugs metabolic degradation and produce little cardiac arrhyth- Nitrous oxide is the only nonhalogenated anesthetic gas mia. It is the least potent of the inhalational anesthet- ation, so this reduces the need for muscle relaxants during ics, and it does not reduce consciousness to the extent surgery. They cause more respiratory depression, however, required for major surgical procedures. Desfurane and sevofurane have a more rapid rate of Nitrous oxide is frequently used as a component of balanced induction and recovery than other halogenated anesthetics anesthesia in combination with another anesthetic agent do, but desfurane is irritating to the respiratory tract, so this and other drugs (see later). The nitrous oxide in balanced limits the concentrations of this agent that can be adminis- anesthesia provides greater analgesia and enables the use of tered during induction. Sevofurane is close to an ideal anes- a lower concentration of the other anesthetic agent. It exhibits a rapid and smooth induction and recovery, Because nitrous oxide has a low blood : gas partition coef- and it causes little cardiovascular or other organ system fcient, induction and recovery are rapid when it is used. Although diazepines, opioids, and other compounds such as pro- these effects are minimal during acute exposure, chronic pofol. These drugs are used for a variety of purposes, exposure to nitrous oxide can cause megaloblastic anemia. The properties of parenteral and sedation during surgery while maintaining a suffcient anesthetics are given in Table 21-4. Fospropofol is a phosphory- of neuroleptanesthesia include chest wall rigidity, which is lated prodrug of propofol. Fentanyl has a much shorter half-life than does they are primarily used for induction of anesthesia. Their use droperidol, and supplemental doses of fentanyl may be is followed by the administration of an inhalational anes- needed during long surgical procedures. Both drugs have a rapid onset Fentanyl and sufentanil, a closely related opioid, are also of action, causing unconsciousness in about 20 seconds. Thiopental is accumulated anil is unique, because it is metabolized extremely rapidly in fat and muscle. It is more slowly eliminated from the body, by esterases in the blood and tissues (see Chapter 23). Either drug can depress car- Ketamine is chemically and pharmacologically related to diovascular and respiratory function. It has a rapid onset of action with low fore is more suitable for use as an anesthetic. This type of anes- gesic properties, it is also administered intravenously or epi- thesia is characterized by analgesia, reduced sensory percep- durally in combination with other drugs for surgical or tion, immobility, and amnesia. For example, it is used to anesthetics, ketamine usually increases blood pressure, but it provide anesthesia during cardiac surgery (e. The main artery bypass grafting), because it does not cause cardiovas- drawback of ketamine is its tendency to cause unpleasant cular toxicity. Fentanyl does not produce amnesia or com- effects during recovery, including delirium, hallucinations, plete loss of consciousness, so it is often combined with a and irrational behavior. Droperidol is a preoperative sedation as well as for endoscopy and other butyrophenone compound whose properties are similar to diagnostic procedures that do not require a high level those of haloperidol (see Chapter 22). Although its onset of action is slower than that Chapter 21 y Local and General Anesthetics 219 of thiopental or propofol, it has the advantage of causing 2. Epinephrine is sometimes added to commercial local little cardiovascular or respiratory depression. Which of the following characteristics is used to quanti- with surgical and diagnostic procedures. Autonomic tate and compare the potency of gaseous general and sensory nerves are blocked more easily than are anesthetics? The nonionized form (C) blood : brain partition coeffcient permeates neuronal membranes, and the ionized form (D) rate of uptake and elimination binds to the internal surface of sodium channels. Muscle rigidity can be a side effect of which intravenous nitrous oxide and enfurane) and parenteral agents anesthetic? Nitrous oxide has a low coeffcient and a rapid Answers And explAnAtions rate of induction. The unprotonated form of the local • Parenteral anesthetics are used to induce anesthesia anesthetic molecule passes through the neuronal mem- and to provide anesthesia during minor surgical and brane and is changed to the protonated form in the cyto- diagnostic procedures. Answer A, increasing K+ conductance tion with other anesthetics during major surgical procedures. Local anesthetics exert their effects by which one of the receptors, is the action of a receptor antagonist. E, blocking by a direct action only at the synapse, again, (A) increasing K+ conductance and hyperpolarizing is not the action of an local anesthetic, which can block nerves all along the nerve fber. The answer is A: to decrease the rate of absorption of (C) inactivating the Na+,K+-adenosine triphosphatase the local anesthetic. Although nitrous oxide anesthetic at the nerve ion channel, are wrong because no has the fastest rate of induction and is safe to use, the evidence exists for epinephrine having this effect. Answer potency is such that one would have to administer the D, to enhance the distribution of local anesthetic, is gas under hyperbaric conditions for it to be the sole incorrect because epinephrine affects the pharmacoki- inhalational agent. Fentanyl is a potent opioid inhalational agents to determine potency, is defned as the agonist given as part of balanced anesthesia. It can cause percent concentration in the administered air that pro- chest wall (truncal) rigidity because of interactions in the duces no response to surgical incision in 50% of the striatum. Answers A, C, and D are measures of the azolam, C, ketamine, D, propofol, or E, thiopental. In contrast, affective disorders are emotional distur- about 1% of the world’s population. Its hallmarks are delu- bances in which the mood is excessively low (depression) or sions, hallucinations, disorganized thinking, and emotional high (mania). Several forms of the disease, including para- have been made in the treatment of these disorders. The noid, disorganized, and catatonic forms, are differentiated newer antipsychotic drugs used to treat schizophrenia and on the basis of symptoms. Delusions Affective fattening Disorganized speech Lack of motivation Dopamine Hypothesis Disorganized thinking Lack of pleasure (anhedonia) Many hypotheses exist regarding the biologic basis of Hallucinations Poverty of speech (alogia) schizophrenia. According to the dopamine hypothesis, schizophrenia results from abnormalities in dopamine neu- Insomnia Social isolation rotransmission in mesolimbic and mesocortical neuronal pathways (Box 22-2).Share this