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Activation of the remainder of the right ventricle was delayed; left ventricular activation did not change discount 10mg female cialis fast delivery. These studies purchase 10mg female cialis with visa, however purchase female cialis from india, not only were limited by the small number of patients but by the fact that the authors did not consider myocardial disease and did not adequately address the effect of axis deviation discount female cialis online amex. Intervals (in milliseconds) measured from the conduction system electrograms to the onset of ventricular activation are shown. Sequential electrograms were recorded along the length of the right bundle branch before and after repair despite the presence of right bundle branch block after repair. Unfortunately, we did not record right bundle potentials or distal His potentials to localize the source of H- V prolongation (see the following discussion). We therefore defined local activation as the point on the 1-cm variable-gain electrogram at which the largest rapid deflection crossed the baseline. When a fractionated electrogram was present without a surface discrete deflection >1 mV in amplitude, we used the rapid deflection of highest amplitude as local activation time. In addition, we measured the onset and offset of local activation from the fixed-gain electrogram from the time the electrical signal reached 0. We defined transseptal conduction time as the difference between local activation time at the right ventricular septum (usually near the apex) and the earliest left ventricular activation time. We also evaluated the total left ventricular activation time, which was the difference in time from the earliest to the latest left ventricular endocardial activation. The average number of left ventricular sites mapped was 14 ± 3 per patient (range, 8 to 19). After repair, right bundle branch block appeared, and outflow tract activation was delayed. Activation of the right ventricular anterior wall with a normal epicardial breakthrough site was unchanged after repair. In nine patients, this was in the middle third of the left ventricular septum, and in three patients, it was at the apical third of the septum. In the remaining six patients, we observed simultaneous early activation at two left ventricular sites; in two patients, two sites were on the septum (one in the middle third and one at the apical septum), and in one, the apical 13 septum and superior basal free wall. In contrast to the studies of Wyndham, we found that the latest site of left ventricular activation was frequently at the base of the heart in patients with normal axis, while it was more 24 variable in those with left axis (Table 5-1). The earliest activity in local anteroseptal sites was similar in the normal and cardiomyopathic groups, at 23 ± 9 and 23 ± 19 msec. Role of catheter mapping in the preoperative evaluation of ventricular tachycardia. Using the difference from the earliest to latest activation times, total left ventricular endocardial activation was also much greater in the group with prior infarction (119 ± 32 msec) than in the other two groups (81 ± 26 and 61 ± 15, respectively) (p < 0. Total left ventricular activation time, as measured by the earliest onset to the latest offset of the fixed-gain electrograms, was also much greater than in the group with prior infarction: 219 ± 77 msec versus 126 ± 37 msec in the normal patients and 125 ± 22 msec in the patients with cardiomyopathy. Frequently, the latest site to be activated was within the site of prior infarction. The interval between local activation at the right ventricular apex and the earliest rapid deflection noted in the left ventricle (i. However, if one measured the interval between local activation at the right ventricular apex and the rapid deflection at the corresponding left ventricular site (site 2), it was longer, averaging 46 ± 50 msec; we noted no differences in any of the three groups. We believe that this represents activation within the septum, which is thinner, and probably represents the right and medial part of the intraventricular septum. Patients with cardiomyopathy and normal hearts have thicker septa and therefore do not record right and intramural septal recordings from the endocardial surface of the left ventricle. One patient had a normal heart, three had cardiomyopathy, and three had prior infarctions. Patients with prior and extensive infarction had the longer left ventricular activation times than those patients with no heart disease or cardiomyopathy. In patients with cardiomyopathy, left ventricular endocardial activation is rapid and smooth. In contrast, in patients with infarction, left ventricular endocardial activation is markedly delayed and associated with abnormal conduction, manifested by fractionated electrograms and narrowed isochrones. Higher density mapping (60 to 200 sites) using the Carto System (Biosense) has confirmed these data. The fractionated electrograms and 25 delayed activation form an arrhythmogenic substrate (see Chapters 11 and 13). In those patients with large anterior infarctions, the bulk of their distal specialized conducting system has been destroyed. As a consequence, their endocardial activation is via muscle-to-muscle conduction and thus is much slower. Note early breakthrough at apical septum (site 2, 65 msec) and basal superior free wall (site 12, 64 msec). The isochrones are widely spaced, demonstrating a normal left ventricular endocardial activation. The data again demonstrated that left ventricular endocardial activation patterns and conduction times were markedly influenced by the site and extent of prior infarction. We always observed longer endocardial activation times in patients with large anterior infarctions. Left ventricular activation times in patients with inferior infarction were intermediate between those without heart disease and those with anterior infarction. Thus, inferior infarction would have less of an effect on total endocardial activation. These include (a) phase 3 block in which the initial aberrant complex is caused by encroachment on the refractory period (phase 3 of the action potential); (b) acceleration-dependent block in which at critical increasing rates (but well below the action potential duration) block occurs; (c) phase 4 or bradycardic-dependent block, which is due to a loss of resting membrane potential owing to disease and/or phase 4 depolarization; and (d) retrograde concealment in which retrograde penetration of a bundle branch renders it refractory to subsequent beats. Both acceleration- dependent and bradycardic-dependent block are manifestations of a diseased His–Purkinje system and should be thought of as abnormal. Unlike chronic bundle branch block, the site of block during aberration can shift. The figure is displayed similarly to the electroanatomic map shown in Figure 5-14. Thus, there appears to be some cycle length dependency of the site of block, and shifts can occur. Left ventricular endocardial activation during right ventricular pacing: Effect of underlying heart disease. Left ventricular local activation times (in milliseconds) are indicated with 10-msec isochrones. Left ventricular endocardial activation during right ventricular pacing: effect of underlying heart disease. A shifting site of block should ultimately lead to resumption of normal conduction unless persistence of retrograde concealment is also present. Left ventricular endocardial activation during right ventricular pacing: effect of underlying heart disease. Longitudinal dissociation in His bundle may cause individual fascicular block, which has been suggested by the observation that catheter manipulation in the His bundle region can produce left anterior hemiblock. In this figure, a leftward shift in axis is accompanied by H-V prolongation, which is caused by a 70-msec increment between proximal and distal His bundle recordings. The basic atrial cycle length is constant at 700 msec, and progressively shorter atrial coupling intervals (A1- A2) are shown. Although not labeled, H1-V1 and H2-V2 values measure the same in all panels, and the H1-H2 therefore equals V1-V2. Pertinent deflections and intervals are labeled and for the most part self-explanatory. Site of conduction delay during functional block in the His-Purkinje system in man. Distinguishing between the intra-His site and the truncal site just proximal to the division of the right and left bundle is impossible; however, I believe that in the majority of cases block at a very proximal site is responsible for both transient and permanent bundle branch block. In fact, when bifascicular block involving both bundle branches is observed, I believe it is only when the site of conduction delay and/or block is proximal that the risk of developing spontaneous heart block is increased. This is an important concept when one uses intracardiac recordings to predict risk of A-V conduction disturbances (see following discussion).

Obese children who Overgrowth by 1–3 cm buy on line female cialis, especially in femur discount 10 mg female cialis free shipping, in children require to lose weight should be monitored 10mg female cialis mastercard. Angular To teach the importance of regular physical activity deformities cheap 10 mg female cialis visa, shortening or both occur because of closure of (moderate to vigorous) as a means of safeguarding physes. Fracture healing is more rapid owing to high growth against illness during adulthood. To encourage parents to serve as role models by participating in regular physical activity along with the Patterns child. Tese may be complete (most common), greenstick, buckle To work with community schools, to support daily (torus), plastic deformation (bend), and epiphyseal which physical education in these schools and to promote are further subdivided into fve groups for prognostic moderate to vigorous activity tasks in physical educa- predictions. A close reduction may be warranted in humerus, phalangeal, lateral malleolar, metatarsal, toe phalanges and toddler fractures. Indications for operative stabilization include: Displaced epiphyseal fractures Special Features Displaced intra-articular fractures Teir distinct peculiarities compared to adult fractures on Unstable fractures account of major anatomic, physiologic and biochemical Fractures in the multiply injured child diferences. Contact/collision sports include hockey, football, wrestling, boxing, judo, karate, etc B. Every child needs to have a good pediatric checkup before takes up a regular sport 5. B 841 Clinical Problem-solving Review 1 A 12-year-old girl, an average student of class 7, presents with excessive tallness (height 162 cm), abnormally long fngers and toes, hyperextensible joints and deteriorating vision. Review 2 A 2-month-old infant being treated for staphylococcal lobar pneumonia with ampicillin plus cloxacillin develops high fever with infammatory swelling of the metaphysis of the right femur. Why did this child develop this complication in spite of being treated with ampicillin and cloxacin which are known to effective in staphylococcal pneumonia? Homocystinuria which is excluded by demonstrating a negative sodium pruside specifc amino acid studies. The offspring of an affected individual run 50% risk of inheriting the number 15 chromosome with Marfan mutation and thus getting affected. The problem of multidrug resistant strains of Staphylococcal aureus seems to be responsible for poor response to ampicillin and cloxacillin. Metaphysis is the most vulnerable site for acute osteomyelitis as a result of hematogenous spread from a distant focus on account of a sluggish circulation and lack of phagocytic cells. In respect of the adopting parent T e most common reason for adoption is a viable z A Hindu cannot adopt more than one male or a female child. Most children that are available for adoption come z The mother of an illegitimate child is entitled to give the child for from young unwed mothers who fail to keep such children adoption. Remaining reasons for giving the child The guardian is entitled to give the child in adoption under special circumstances such as when the parentage is not known, e. T ough most often adoption is restricted to the couple’s T e adoption laws have been criticized for some relatives, this is, by no means the recommended means of glaring defciencies which leave a room for violation of adoption. Neither taking resort to private adoptions through the laws by various quarters including the Apex Court. Today, moreover, biologic Secondly, an adult orphan cannot be adopted because he parents can anytime contest the adoptive parents’ right to has no guardian. T irdly, an adopted child has got to break continue with the custody of the child. T ese agencies make Adoption and the Pediatrician available to the adopting couple the requisite details about the exact procedure for adoption. T e agencies make T e role of the pediatrician both before and after adoption sure that the adopted child is smoothly placed with the remains important. Secondly, he Adoption Laws should provide adequate safeguard to the adopting couple T e well-known Hindu Adoptions and Maintenance Act by providing correct information about the health status of 1956 governs adoption among the majority community the child to be adopted. In case of minority communities whose personal to the family beneft of his advice for the emotional prob- laws fail to permit adoption, the parents can only be lems of the adopted child as a consequence of overindul- guardians to the adopted children. A few cases were found reduced magnesium in chronic fatigue syndrome seen among Bangladesh refugees during 1971–72. Tremors and rigid- “Infantile meningoencephalitis”, “tremor syndrome”, ity, among other neurologic manifestations, are known “nutritional tremor syndrome”, “syndrome of tremors, to result from such defciency. In view of presence of anemia, Epidemiologic Considerations pigmentation, hair changes, tremors and mental leth- argy, role of zinc defciency in its etiology appears quite Incidence: It accounts for 1–2% of pediatric admissions probable. Acute onset of admissions to the pediatric inpatient department of tremors and their occurrence following intravenous the Snowdon Hospital, Shimla, during 1971–74. At drip or blood transfusion in certain instances are often Jammu, recently, at one time, 6 of our 200 hospitalized cited in support of this hypothesis. A few children may be up to 2 years encephalographic studies have revealed cortical atrophy of age. Te Patiala workers have found patchy fbrosis 5 years with characteristic features of this syndrome. Similar brain, muscle and nerve Nutritional background: Tese infants come from alterations have been seen by us on autopsy material. Most of them are breastfeed and have concomitant malnutrition, especially anemia, though Clinical Features they look plump. Tis is more remarkable over dorsal aspect of hands (especially over terminal phalanges), Phenobarbital 3–5 mg/kg/day (O) in one or two doses feet, knees, ankles, axillae, buttocks, lower abdomen and Chlorpromazine 2–3 mg/kg/day (O) in three divided doses medial aspect of thighs. Tere is history of regression of Carbamazepine 10–20 mg/kg/day (O) in two divided doses motor and mental milestones in the recent past. Te onset Sodium Valproate 20 mg/kg/day (O) in two to three divided doses of tremors is preceded or accompanied by some stress Propranolol 0. Tese tremors usually disappear during sleep in most cases; in others their intensity remarkably form of high voltage sharp waves and spikes with a slow diminishes. Even to ascertain if these show disappearance during a longer trunk may be involved. Tey keep tossing their head from side to side with the saliva drooling from mouth and have Treatment dull, expressionless look. Mental and motor development Since anemia and malnutrition are always present (though is impaired in all. Zinc 12 megaloblastic, normocytic-normochromic, iron-defciency in therapeutic doses is strongly recommended. Incidence of variable nutritional def- Administration of phenobarbital orally in the initial ciencies and superadded infestations/infections, including stage is advantageous. Incomplete forms, say the so-called may even control these, protects the child from continued pretremor state, with all the features of the syndrome exhaustion and provides much needed psychologic relief to minus tremors are also known. Furthermore, it may well help in cutting ment of tremors in such untreated infants in due course. Some workers Course have reported encouraging response to chlorpromazine, propranolol, carbamazepine, valproate, etc. Pretremor (prodromal) phase is characterized by these measures, the child should receive adequate treatment regression of attained milestones, motor and/or mental for his other associated problems like intestinal parasites, slowness with vacant expressionless facies, anemia, respiratory infection or tuberculosis. Tremor or classical phase is characterized by appear- With the above measures, response is encouraging. As the ance of tremors on top of clinical features of pretremor nutritional status (including hemoglobin) improves, trem- state. Posttremor or recovery phase is characterized by regres- Electroencephalographic changes seen in advanced sion of tremors and other features of the syndrome. Te cases perhaps take much longer time to regress even mental dullness continues for several months. Investigations should be aimed at fnding the Tis term refers to the sudden, unexpected death of an extent and morphologic type of anemia, determining the apparently healthy infant, usually 2–3 months of age, who nutritional status and detecting coexisting infections and had been put to the bed without any suspicion of such an infestations. Allergy to cow milk, enlargement of thymus, sufocation, defciency of parathyroids or adrenals, hypernatremia and fulminant respiratory infection causing laryngeal obstruction and/or spasm fgure among the large number of conditions/factors that are incriminated in its etiology. Such states as prolonged sleep, apnea, (associated with central nervous system Fig. Te characteristic features include infantilism, respiration, heart rate and temperature, and postnatal remarkable absence or diminution of subcutaneous fat, growth retardation. Te parents must be questioned about generalized alopecia (including missing eyebrows) and other the infant’s feeding, medications, etc. Physical examination should concentrate on infant’s Physical development in infancy is not signifcantly afected. Te infant needs to be observed Manifestations such as scleroderma, midfacial while he is being fed.

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Biochemical examination shows increase in proteins Although there may be short periods of wakefulness order female cialis 20 mg line. If treatment is delayed or Supportive investigations include chest X-rays discount 20 mg female cialis mastercard, inadequate generic female cialis 20 mg free shipping, hydrocephalus invariably develops in infants and small children generic 10 mg female cialis visa. Controlling Seizures Te child should receive an anticonvulsant like diazepam, phenobarbital, and phenytoin to control convulsions. Supportive Measures Good nursing care Maintenance of fuid and electrolyte balance and nutrition Treatment of evolving complications like decerebra- tion, hydrocephalus. Clinical Features Corticosteroids Onset may be acute, subacute or vaguely chronic In order to reduce cerebral edema and risk of such Te manifestations are mild, moderate or severe, complications as arachnoiditis, fbrosis, adhesions and depending upon the severity of pathologic lesions of spinal block, steroids are strongly recommended. But they keep forming granulomatous tissue which is infratentorial in majority of the cases. Granulomata may, however, be supratentorial as well as scattered over multiple sites. Clinical Features Unlike other forms of tuberculosis, children sufering from tuberculoma may appear adequately built and well-nourished. Onset is usually gradual with vomiting, headache, cerebellar ataxia and diminished vision. It usually is seen as Pathology a discrete lesion with a signifcant amount of surrounding Histopathologically, the most important and consistent edema (Fig. Tis change is must be distinguished from that of neurocysticerosis predominant in white matter though gray matter may also (described later in this chapter). Tere is, however, no signifcant involvement of the Antituberculous chemotherapy should be started as meninges though a few tiny tubercles in meninges or brain soon as the diagnosis has been made. Poor response is an indication for surgical excision rather than Diagnosis mere burr holes. Te presence of miliary, disseminated or intrathoracic tuberculosis helps in recognizing this entity. Even in the absence of clinical evidence of tuberculosis, the diagnosis may be suggested by exclusion of other conditions and, at times, only by brain biopsy on autopsy. About one-half of the intracranial space-occupying lesions are accounted by tuberculoma in tropical infants and children. Tuberculoma is always secondary to a primary tuberculous Most often, pediatric tuberculoma is solitary and infratentorial, located at lesion elsewhere in the body. Tere is, however, z Metabolic:Hyperbilirubinemia of newborn, diabetic ketoacidosis, considerable overlap and the two groups should uremia, hypoglycemia, Reye syndrome, electrolyte imbalance not be considered as absolutely distinct and airtight z Toxic: Poisoning by lead, insecticides, carbon monoxide z Physical and Environmental: Hyperpyrexia, heat stroke. Etiologic Considerations Te occurrence of viral encephalitis as a complication of Clinical picture shows rapid variation from hour to hour. Confusing neurologic involvements, including measles, chickenpox, mumps, herpes simplex and rabies tremors and sensory changes, may be observed. In addition, there is a relatively commoner Hemiparesis is common; so, are respiratory irregularities. Occasionally, myocarditis and hypotension vast majority of these cases are of viral etiology though complicate the picture. In all In a number of conditions that could fall under the probability, enteroviruses are responsible in most. Certain title progressive encephalopathy, the child exhibits some bacterial infections like shigellosis, salmonellosis and degree of mental retardation (Box 28. Besides, pertussis, enteric fever or tuberculosis may Diagnosis cause an encephalopathy that clinically resembles viral Diagnosis is essentially clinical and is by exclusion of encephalitis. Sugar is either normal or little viral encephalitis, the etiologic agent appears to be non- raised. Manifestations include change in z Galactosemia sensorium, varying from lethargy to coma, fever, vomiting z Hurler syndrome z Tay-Sach disease and convulsions. Some children demonstrate peculiar z Leukodystrophy behavior, hyperactivity, altered speech and ataxia. Symptomatic: General supportive measures form the Etiopathogenesis 529 cornerstone of management. It is advisable that such a Infections and vaccines are responsible for this rare dis- patient is treated in a hospital. Pathological changes are periventricular in location, care, involving attention to skin, bowel, bladder, etc. This is especially so in the initial (which enhance with contrast) in white matter. Magnetic resonance imaging: White matter lesions; z Anticonvulsants:Convulsions should be controlled with phenobarbital, paraldehyde, chloral hydrate, spinal cord and basal ganglia lesions. Most cases need anticonvulsant therapy Treatment, aimed at suppressing the infammation round the clock. Tree to fve z Reduction of hyperpyrexia: High fever should be days course of methylprednisolone given by drip fol- controlled by tepid sponging and/or antipyretics. Additionally, physiotherapy and occupational therapy z Maintenance of airway: Frequent suctioning help improve strength, balance and function. Tis is a generalized mitochondrial disorder in which z Corticosteroids: Most authorities feel that the encephalopathy occurs secondary to liver dysfunction, benefit of steroid therapy should be given. The true usually following administration of salicylates in a child value of such a therapy is not established. For details, See Chapter 30 (Pediatric with sequelae like mental retardation, epilepsy, behavioral Hepatology and Pancreatology). Trough foramina of Luschka and Magendie in the roof of the fourth ventricle, it enters into the subarachnoid spaces. Te overwhelming amount goes to the subarachnoid villi near the sagittal sinus where it gets absorbed. Etiology It may be because of: Increased production (communicating hydrocephalus), e. Note the “sunset” sign in the Obstruction to the fow (noncommunicating hydro- eyes in addition to enlarged head (43 cm) in this neonate. Acquired hydrocephalus develops later, in association Interference with absorption, e. Te cracked-pot (Macewen) sign may be Clinically, the causes are: elicited by percussing the head. A resonant note as a result Congenital hydrocephalus: It may be associated with: of separation of sutures is present. Mental through foramen magnum, into upper cervical part faculty and other neurologic manifestations vary with the of the spine. Arrested hydrocephalus is z Dandy-Walker anomaly in which congenital the term applied when there is no more progression in the septa or membranes block the outlet of the fourth head size. Hydrocephalus occurring late in childhood is z Malformations or stenotic lesions of aqueduct not accompanied by big head. Diagnosis z Traumatic birth trauma, head injury, intracranial It is easy to diagnose hydrocephalus. Tis may need extensive tuberculoma, subdural hematoma or abscess, radiologic studies of the skull, including ventriculography gliomas, etc. Diferential diagnosis is primarily from megaloencephaly or hydraencephaly, chronic subdural Clinical Features efusion or hematoma, cerebral atrophy, and thickened Congenital hydrocephalus is present right at birth or cranium due to rickets, chronic anemia, osteogenesis becomes apparent in the frst few month of life. Prognosis after shunt is, organisms include anaerobic bacteria, Streptococcus however, not uniformly good (Box 28. Infrequently, fungus and amebic Complications infections may also be responsible for the disease. Te most common location of the abscess is the cere- Intrauterine surgical intervention in fetal hydroce- bellum. When it is in the cerebrum, the site is usually in the phalus that is frequently accompanied by cerebral temporal or frontal lobe. Pathologically, the abscess Prognosis is a layer of vascularized granulation tissue encapsulating Following appropriate medical and neurosurgical treat- pus and other glial cell proliferation. A long-term follow-up in a multidisciplinary setting Manifestations of toxemia may include high or low is warranted. Without treatment, mortality is as high as irregular fever, chills, rigors and leukocytosis 50–60%. Sepsis of the shunt, usually with Staphylococcus epidermidis Obstruction of shunt Treatment Bacterial colonization. Once the existence of subdural efusion is suspected, a subdural tap should immediately be done See Chapter 48 (Miscellaneous and Unclassifed Issues).

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We wish to know if we may conclude that the mean function score for a population of similar women subjects with severe hip pain is less than 75 purchase 20 mg female cialis amex. The ages (years) of the subjects were: 62 62 68 48 51 60 51 57 57 41 62 50 53 34 62 61 Source: Phamornsak Thienprasiddhi buy 10mg female cialis, Vivienne C cost of female cialis. Hood purchase generic female cialis online, “Multifocal Visual Evoked Potential Responses in Glaucoma Patients with Unilateral Hemifield Defects,” American Journal of Ophthalmology, 136 (2003), 34–40. Can we conclude that the mean age of the population from which the sample may be presumed to have been drawn is less than 60 years? Can it be concluded from these data that the population mean is greater than four visits per patient? Do these data provide sufficient evidence to indicate that the population mean is greater than 25? The mean time (computed from the sample data) required for ambulances to reach their destinations was 13 minutes. A sample of 20 yielded the following values: 132, 33, 91, 108, 67, 169, 54, 203, 190, 133, 96, 30, 187, 21, 63, 166, 84, 110, 157, 138 Let a ¼ :01. A simple random sample of 64 males from the population had a mean systolic blood pressure reading of 133. Assume that weights in the population are approximately normally distributed with a variance of 49. Do the sample data provide sufficient evidence for us to conclude that the mean weight for the population is less than 70 kg? As was done in the previous section, hypothesis testing involving the difference between two population means will be discussed in three different contexts: (1) when sampling is from normally distributed populations with known population variances, (2) when sampling is from normally distributed populations with unknown population variances, and (3) when sampling is from populations that are not normally distributed. Sampling from Normally Distributed Populations: Population Variances Known When each of two independent simple random samples has been drawn from a normally distributed population with a known variance, the test statistic for testing the null hypothesis of equal population means is ð x1 À x2 m1 À m2 0 z ¼ sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi (7. The data consist of serum uric acid readings on 12 individuals with Down’s syndrome and 15 normal individuals. Solution: We will say that the sample data do provide evidence that the population means are not equal if we can reject the null hypothesis that the population means are equal. The data constitute two independent simple random samples each drawn from a normally distributed population with a variance equal to 1 for the Down’s syndrome population and 1. When the null hypothesis is true, the test statistic follows the standard normal distribution. Conclude that, on the basis of these data, there is an indication that the two population means are not equal. Since this interval does not include 0, we say that 0 is not a candidate for the difference between population means, and we conclude that the differenceisnotzero. Sampling from Normally Distributed Populations: Population Variances Unknown As we have learned, when the population variances are unknown, two possibilities exist. We consider first the case where it is known, or it is reasonable to assume, that they are equal. A test of the hypothesis that two population variances are equal is described in Section 7. Population Variances Equal When the population variances are unknown, but assumed to be equal, we recall from Chapter 6 that it is appropriate to pool the sample variances by means of the following formula: ð n À 1 s2 þ n À 1 s2 2 1 1 2 2 sp ¼ n1 þ n2 À 2 When each of two independent simple random samples has been drawn from a normally distributed population and the two populations have equal but unknown variances, the test statistic for testing H0: m1 ¼ m2 is given by ð x1 À x2 m1 À m2 0 t ¼ sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi (7. Subjects used a modified wheelchair to incorporate a rigid seat surface to facilitate the specified experimental measurements. Interface pressure measurement was recorded by using a high-resolution pressure-sensitive mat with a spatial resolution of four sensors per square centimeter taped on the rigid seat support. During static sitting conditions, average pressures were recorded under the ischial tuberosities (the bottom part of the pelvic bones). The data constitute two independent simple random samples of pressure measurements, one sample from a population of control subjects and the other sample from a population with lower-level spinal cord injury. We shall assume that the pressure measurements in both populations are approximately normally distributed. When the null hypothesis is true, the test statistic follows Student’s t distribution with n1 þ n2 À 2 degrees of freedom. Chow, “Pelvic Movement and Interface Pressure Distribution During Manual Wheelchair Propulsion,” Archives of Physical Medicine and Rehabilitation, 84 (2003), 1466–1472. We fail to reject H0, since À1:7341 < À:569; that is, À:569 falls in the nonrejection region. The critical value of t0 for a one-sided test is 1ÀðÞa=2 2 found by computing t0 by Equation 7. For a two-sided test, reject H if the computed value of t0 is either greater than or 0 equal to the critical value given by Equation 7. Fora one-sided testwiththerejectionregioninthe right tailofthesamplingdistribution, reject H if the computed t0 is equal to or greater than the critical t0. For a one-sided test with a 0 left-tail rejection region, reject H if the computed value of t0 is equal to or smaller than the 0 negative of the critical t0 computed by the indicated adaptation of Equation 7. Measures of this variable were calculated from the aortic diameter evaluated by M-mode echocardiography and blood pressure measured by a sphygmomanometer. In the 15 patients with hypertension (group 1), the mean aortic stiffness index was 19. We wish to determine if the two populations represented by these samples differ with respect to mean aortic stiffness index. The sample sizes, means, and sample standard deviations are: n1 ¼ 15; x1 ¼ 19:16; s1 ¼ 5:29 n2 ¼ 30; x2 ¼ 9:53; s2 ¼ 2:69 2. The data constitute two independent random samples, one from a population of subjects with hypertension and the other from a control population. We assume that aortic stiffness values are approxi- mately normally distributed in both populations. Before computing t0 we calculate w ¼ 1 2 2 ð 5:29 =15 ¼ 1:8656 and w2 ¼ 2:69 =30 ¼ :2412. On the basis of these results we conclude that the two population means are different. This will allow the use of normal theory since the distribution of the difference between sample means will be approximately normal. When each of two large independent simple random samples has been drawn from a population that is not normally distributed, the test statistic for testing H0: m1 ¼ m2 is ð x1 À x2 m1 À m2 0 z ¼ sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi (7. If the population variances are known, they are used; but if they are unknown, as is the usual case, the sample variances, which are necessarily based on large samples, are used as estimates. Sample variances are not pooled, since equality of population variances is not a necessary assumption when the z statistic is used. One focus of the study was to determine if there were differing levels of the anticardiolipin antibody IgG in subjects with and without thrombosis. McNearney, “Analysis of Risk Factors and Comorbid Diseases in the Development of Thrombosis in Patients with Anticardiolipin Antibodies,” Clinical Rheumatology, 22 (2003), 24–29. The statistics were computed from two independent samples that behave as simple random samples from a population of persons with thrombosis and a population of persons who do not have thrombosis. Since the population variances are unknown, we will use the sample variances in the calculation of the test statistic. Since we have large samples, the central limit theorem allows us to use Equation 7. When the null hypothesis is true, the test statistic is distributed approximately as the standard normal. These data indicate that on the average, persons with thrombosis and persons without thrombosis may not have differing IgG levels. When testing a hypothesis about the difference between two populations means, we may use Figure 6. Alternatives to z and t Sometimes neither the z statistic nor the t statistic is an appropriate test statistic for use with the available data. When such is the case, one may wish to use a nonparametric technique for testing a hypothesis about the difference between two population measures of central tendency. The Mann-Whitney test statistic and the median test, discussed in Chapter 13, are frequently used alternatives to the z and t statistics. For each exercise, as appropriate, explain why you chose a one-sided test or a two-sided test. Discuss how you think researchers or clinicians might use the results of your hypothesis test. What clinical or research decisions or actions do you think would be appropriate in light of the results of your test?

It is then nec- essary to dissect progressively deeper into the hepatic parenchyma using the harmonic shears while separating the edges of the liver with the left handed forceps discount female cialis line. Sometimes a ffth trocar is needed for the assistant to insert a grasper to carefully move the tumor mass purchase female cialis australia. Atraumatic grasping forceps allow the minute structures to be coagulated as they pass through this groove buy discount female cialis line. All bile ducts should be clipped or tied; it is not recommended to rely on the harmonic shears to seal bile ducts purchase female cialis 20 mg without a prescription, as this can lead to postoperative bile leaks. Clips must be employed for larger vessels, and it is recommended that a double clipping technique be used to avoid inadvertent dislocation of a single clip on a vascular pedicle. The irrigation/ aspiration probe should be used in a deep groove in the liver to keep the operating feld dry. The need to maintain a bloodless feld by means of constant rinsing of the dissection area cannot be overemphasized. A 5–8 cm solid tumor can be extracted in a bag without diffculty by enlarging the fascial incision at the umbilicus so that the extracted specimen is left intact. Left Lateral Segmentectomy This approach is aimed at larger tumors on the left lobe for which a wedge resection or limited segmentectomy may prove to be incomplete and therefore inadequate treatment. Larger lesions of the left lobe may also be best dealt with by a formal resection when a wedge procedure might actually prove to be more diffcult and hazardous. Laparoscopic left lateral segmentectomy, however, should only be considered by surgeons who have extensive experience in both laparoscopy and liver surgery. This allows for simultaneous maneuvers by two surgeons operating in harmony (four hands approach) - one doing the dissection and the other concentrating on hemostatic control and the clipping of all ves- sels. The lead surgeon usually operates the ultrasonic dissector while the second surgeon applies clips and divides the isolated vessels. This includes the left hepatic vein which must be iso- lated before the liver capsule is incised. A Pringle maneuver can then he performed using an atraumatic right-angled dis- sector, and a tourniquet is placed around the porta hepatis (Fig. Then, after full mobilization of the left triangular ligament, it is possible to retract the left lobe inferiorly using an atraumatic fan retractor allowing one to see the insertion of the left hepatic vein on the vena cava. This is an extremely dangerous maneuver and should be done only by a very skilled laparoscopic surgeon. Now a right-angled atraumatic dissector is introduced and the left hepatic vein is encircled using gentle blunt dissection and a long tie placed around it. An atraumatic clamp should always be kept handy in the vicinity in case there is bleeding that requires immediate compression and clamping. Therefore, unless this vessel is safely controlled within seconds of hemorrhaging, the surgeon should opt for an immediate safe conversion. If the left hepatic vein has a short course outside the liver parenchyma before joining the inferior vena cava, dissection should not be attempted. During parenchymal dissection one encounters the constituents of the portal pedicle. They are ideally controlled with clips, and reinforced by intracorporeal ligatures when necessary. That said, it is easier to try to secure all vascular elements with clips, as it is diffcult to apply sutures laparo- scopically in the liver as the tissue is very friable. In general, the lobectomy specimen is then placed in an extraction bag and can be withdrawn only if it undergoes some degree of morcelation. The greater omentum can be used to cover the raw surface of the liver at the end of the procedure. After left lateral segmentectomy, the procedure concludes with the placement of two suction drains near the edge of the wound to collect any minor persistent oozing of blood or bile and to prevent hematomas. Smaller resections such as limited segmentectomies are done in the same way, with the same concern for hemostasis and control of the biliary ducts. Vascular white staples can easily control the hemostasis of small pedicles but it is advisable to start the resection by scar- ring the capsule with a hook. In general, as demonstrated in gynecological series, the associated risk in laparoscopic surgery is minimal. The risk is, however, not insignifcant during surgery of solid organs such as the liver and spleen because they are linked directly to the inferior vena cava and to the heart. The effects of emboli are sometimes initially detected only by the recovery room staff, who must be made aware of this possible complication. Right Hepatectomy This is the most advanced laparoscopic liver resection, and perhaps the most complex laparoscopic procedure, that should only be performed by experienced laparoscopic liver surgeons. All instruments are used as described above, including the harmonic shears and the cutters with vascular loads. A Pringle maneuver is always performed frst, and the operation follows the rules of open liver surgery. A camera; B surgeon’s right hand for harmonic shears; C second surgeon’s left hand; D second surgeon’s right hand; E fan or suction irrigation device. Minor hemorrhage can be con- Prevention of trolled with unipolar or bipolar atraumatic forceps. With more serious arterial bleeding where there is clearly spurting of blood, it is Complications necessary to grasp the artery with the atraumatic forceps and apply a clip or ligature. The management of venous bleeding in hepatic surgery tends to be more compli- cated, as there is often constant oozing, making hemostasis extremely diffcult. Often tempo- rary compression using laparoscopic 2 × 2 gauze will stabilize the situation. It is also possible to introduce larger 4 × 4 gauze which should be attached to a suture to identify it laparoscopically, and a clip should be placed on the gauze to make it radiopaque. If the bleeding originates from a small lacerated vein, it can generally be controlled with cau- tery, clips, or the fat blade of harmonic scissors. If the venous injury is more extensive, such as to the hepatic vein or a branch of the portal vein, one should not hesitate to con- vert and perform a limited subcostal incision which will then allow precise action and enable the operation to be concluded safely. It should be stressed that conversion is not an admission of failure, but sound surgical judgment. Patient Selection 63 Control of biliary leaks by the use of clips, is generally easy because the biliary drainage can be seen clearly under the magnifcation provided by the laparoscope. Finally, division of these vessels must take place only after their proper control with elec- trocautery, clips, or ligatures. Surgery 146(4):817–823 Baldini E, Gugenheim J, Ouzan D, Katkhouda N, Mouiel J (1999) Orthotopic liver trans- plantation with or without peritoneal drainage: a comparative study. 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Br J Surg 84(3):321–322 Fabiani P, Katkhouda N, Chazal M, Gugenheim J, Mouiel J (1991b) Fenestration of biliary cysts under videocoelioscopy. La Lettre Chirurgicale 10:105 Ferzli S, David A, Kiel T (1995) Laparoscopic resection of a large hepatic tumor. World J Surg 20(5):556–561 Gugenheim J, Mazza D, Katkhouda N, Goubaux B, Mouiel J (1996) Laparoscopic resection of solid liver tumors. Br J Surg 83:334–335 Guibert L, Gayral F (1995) Laparoscopic pericystectomy of a liver hydatid cyst. Surg Endosc 9(4):442–443 Hashizume M, Takenaka K, Yanaga K et al (1995) Laparoscopic hepatic resection for hepatocellular carcinoma.

By N. Diego. Eastern Washington University.