By J. Yokian. Robert Morris College, Pittsburgh, PA. 2019.
Mann–Whitney Statistic and the Wilcoxon Statistic As was noted at the beginning of this section buy cheap rogaine 2 60 ml online, the Mann–Whitney test is sometimes referred to as the 13 rogaine 2 60 ml overnight delivery. Indeed buy rogaine 2 with paypal, many computer packages give the test value of both the Mann–Whitney test (U) and the Wilcoxon test (W) order rogaine 2 overnight delivery. These two tests are algebraically equivalent tests, and are related by the following equality when there are no ties in the data: mmþ 2n þ 1 U þ W ¼ (13. As we see this output provides the Mann–Whitney test, the Wilcoxon test, and large-sample z approximation. Group 1 subjects were employed by the City of Asheville, North Carolina, and group 2 subjects were employed by Mission– St. At the start of the study, the researchers performed the Mann–Whitney test to determine if a significant difference in weight existed between the two study groups. Weight (Pounds) Group 1 Group 2 252 215 240 185 195 220 240 190 302 310 210 295 205 270 312 212 190 202 200 159 126 238 172 268 170 204 268 184 190 220 170 215 215 136 140 311 320 254 183 200 280 164 148 164 287 270 264 206 214 288 210 200 270 170 270 138 225 212 210 190 265 240 258 182 192 203 217 221 225 126 Source: Data provided courtesy of Carole W. May we conclude, on the basis of these data, that patients in the two groups differ significantly with respect to weight? Prior to treatment, researchers studied the blood gas levels in the two groups of rats. May we conclude, on the basis of these data, that, in general, subjects on saline have, on average, lower pO2 levels at baseline? Smirnov, two Russian mathematicians who introduced two closely related tests in the 1930s. Smirnov’s work (7) deals with the case involving two samples in which interest centers on testing the hypothesis that the distributions of the two-parent populations are identical. The test for the first situation is frequently referred to as the Kolmogorov–Smirnov one-sample test. The test for the two-sample case, commonly referred to as the Kolmogorov–Smirnov two-sample test, will not be discussed here. The sample is a random sample from a population with unknown cumulative distribution function F(x). If, however, there is a discrepancy between the theoretical and observed cumulative distribu- tion functions too great to be attributed to chance alone, when H0 is true, the hypothesis is rejected. When values of D are based on a discrete theoretical distribution, the test is conservative. When the test is used with discrete data, then, the investigator should bear in mind that the true probability of committing a type I error is at most equal to a, the stated level of significance. The test is also conservative if one or more parameters have to be estimated from sample data. We wish to know if we may conclude that these data are not from a normally distributed population with a mean of 80 and a standard deviation of 6. The sample available is a simple random sample from a continuous population distribution. Critical values of the test statistic for selected values of a are given in Appendix Table M. The procedure, which is similar to that used to obtain expected relative frequencies in the chi-square goodness-of-fit test, is summarized in Table 13. This particular software program has a nonparametric module that contains nearly all of the commonly used nonparametric tests, and many less common, but useful, procedures as well. Note that it provides the test statistic of D ¼ 0:156 and the exact two-sided p value of. Advantages and Disadvantages The following are some important points of comparison between the Kolmogorov–Smirnov and the chi-square goodness-of-fit tests. The Kolmogorov–Smirnov test does not require that the observations be grouped as is the case with the chi-square test. The consequence of this difference is that the Kolmogorov–Smirnov test makes use of all the information present in a set of data. It will be recalled that certain minimum sample sizes are required for the use of the chi-square test. As has been noted, the Kolmogorov–Smirnov test is not applicable when parameters have to be estimated from the sample. The chi-square test may be used in these situations by reducing the degrees of freedom by 1 for each parameter estimated. The problem of the assumption of a continuous theoretical distribution has already been mentioned. When the assumptions underlying this technique are not met, that is, when the populations from which the samples are drawn are not normally distributed with equal variances, or when the data for analysis consist only of ranks, a nonparametric alternative to the one-way analysis of variance may be used to test the hypothesis of equal location parameters. A deficiency of this test, however, is the fact that it uses only a small amount of the information available. The test uses only information as to whether or not the observations are above or below a single number, the median of the combined samples. Several nonparametric analogs to analysis of variance are available that use more information by taking into account the magnitude of 13. Perhaps the best known of these procedures is the Kruskal–Wallis one-way analysis of variance by ranks (8). The Kruskal–Wallis Procedure The application of the test involves the following steps. The observations are then replaced by ranks from 1, which is assigned to the smallest observation, to n, which is assigned to the largest observation. When two or more observations have the same value, each observation is given the mean of the ranks for which it is tied. The ranks assigned to observations in each of the k groups are added separately to give k rank sums. When there are three samples and five or fewer observations in each sample, the significance of the computed H is determined by consulting Appendix Table N. When there are more than five observations in one or more of the samples, H is compared with tabulated values of x2 with k À 1 degrees of freedom. One of the outcome variables examined was the count of eosinophil cells, a type of white bloodÀÁcell that can increase with allergies. Can we conclude that the three populations represented by the three samples differ with respect to eosinophil cell count? We can so conclude if we can reject the null hypothesis that the three populations do not differ in eosinophil cell count. The distributions of the values in the sampled populations are identical except for the possibility that one or more of the populations are composed of values that tend to be larger than those of the other populations. Critical values of H for various sample sizes and a levels are given in Appendix Table N. The null hypothesis will be rejected if the computed value of H is so large that the probability of obtaining a value that large or larger when H0 is true is equal to or less than the chosen significance level, a. When the three samples are combined into a single series and ranked, the table of ranks shown in Table 13. The null hypothesis implies that the observations in the three samples constitute a single sample of size 15 from a single population. If this is true, we would expect the ranks to be well distributed among the three groups. Consequently, we would expect the total sum of ranks to be divided among the three groups in proportion to group size. Table N shows that when the nj are5,5,and5,the probability of obtaining a value of H ¼ 9:14 is less than. We conclude that there is a difference in the average eosinophil cell count among the three populations. The letter t is used to designate the number of tied observations in a group of tied values. In our example there are no groups of tied values but, in general, there may be several groups of tied values resulting in several values of T. Note also that the effect of the adjustment is to increase H, so that if the unadjusted H is significant at the chosen level, there is no need to apply the adjustment. More than Three Samples/Large Samples Now let us illustrate the procedure when there are more than three samples and at least one of the nj is greater than 5. We wish to determine, by means of the Kruskal–Wallis test, if we can conclude that the average net book value of equipment capital per bed differs among the five types of hospitals.
As described in Chapter 8 rogaine 2 60 ml low cost, patients with A-V nodal reentry have rapid V-A conduction buy discount rogaine 2 60 ml on line. It is the ability to conduct rapidly up the fast pathway retrogradely that allows these tachycardias to be initiated and maintained buy 60 ml rogaine 2 visa. In such instances the H-A interval remains relatively short with little increase as the ventricular pacing rate is increased buy rogaine 2 60 ml on line. Another group of patients with enhanced A-V conduction who have rapid V-A conduction are those with antegradely concealed but retrogradely conducting bypass tracts. In this case, short and fixed V-A intervals are the rule, as they are with other bypass tracts, and retrograde conduction is often maintained at extremely short ventricular paced cycle lengths (<250 msec). The retrograde His and the A are activated in parallel, and the short H-A intervals seen are related to this phenomenon. The H-A intervals, however, tend to be slightly longer than the H-A intervals with retrograde conduction over a fast A-V nodal pathway, particularly at rather long paced cycle lengths. When ventricular cycle lengths are reduced, however, the H-A interval increases somewhat when retrograde conduction proceeds over an A-V nodal pathway. Then, the H-A interval can exceed the H-A interval in patients with retrograde conduction over concealed bypass tracts, because in the latter group the H-A does not reflect linear conduction but rather fixed conduction through both the His–Purkinje system and the bypass tract. Thus, at paced cycle lengths <300 msec, the H-A intervals in patients with concealed retrograde bypass tracts may be (but by no means universally so) shorter than the H-A intervals in those patients with conduction retrogradely through a fast A-V nodal pathway. In fact, the H-A interval in patients using fast A-V nodal pathways is typically shorter than the A-H interval at comparable paced cycle lengths. This is another characteristic typical of patients with dual A-V nodal pathways and A-V nodal reentry (see Chapter 8). In contrast, patients who manifest true atrio-His bypass tracts, as defined previously, have unpredictable V-A conduction. Even when present, V-A conduction in these patients is not as good as A-V conduction. Response to Pharmacologic and Physiologic Maneuvers Patients with enhanced A-V nodal conduction behave differently than those with atrio-His bypass tracts that appear to be physiologically similar to A-V bypass tracts in their response to pharmacologic and physiologic maneuvers. As such, drugs and physiologic maneuvers that profoundly affect A-V nodal conduction without any significant effects on atrial tissue can be used to distinguish the mechanism of enhanced A-V conduction. An increase in the A-V interval in response to drugs such as digoxin, beta-blockers, calcium-blockers, or adenosine suggests that abbreviated A-V conduction is due to enhanced A-V nodal conduction, or if a bypass tract exists, it inserts into the A-V node (Figs. An increase in P-R and A-H intervals in response to atrial extrastimuli suggests the same thing. Carotid sinus pressure and other vagal maneuvers may be used in an analogous fashion to demonstrate that conduction through the A-V node is responsible for the genesis of a short 142 P-R. The change differs markedly from that of the prolongation of A-H and H-V intervals that occurs with these agents in patients with enhanced A-V nodal conduction. With atrio-His bypass tracts, both the A-H and H-V intervals prolong suddenly and markedly, because the measured A-H interval during sinus rhythm actually reflects retrograde conduction to the recorded His bundle from the site of insertion of the bypass tract and does not reflect a linear measurement of either A-V nodal or His–Purkinje conduction. Data from studies performed at a basic cycle length of 600 msec are shown in circles, and those from studies performed at 500 msec are shown in triangles. At every A1-A2 interval, the A2-H2 interval is longer at the shorter drive cycle length. Supraventricular tachycardia in Lown-Ganong-Levine syndrome: intranodal versus antinodal reentry. The A-H interval also prolonged somewhat, and the shortest cycle length with 1:1 A-V conduction increased. In patients without enhanced A-V nodal conduction, the opposite effects occurred: The functional refractory period of the A-V node shortened, the cycle length of the Wenckebach shortened, and there was a slight shortening of the A-H interval. These findings suggest that in patients with enhanced A-V nodal conduction, sympathetic tone predominates, whereas in those patients without enhanced A-V nodal conduction, parasympathetic tone predominates. It is of note, however, that regardless of the differential effects of autonomic blockade in the two patient groups, patients with enhanced A-V nodal conduction still had shorter A-H intervals, shorter cycle lengths with 1:1 A-V conduction maintained, and shorter functional refractory periods of the A-V node. The effective refractory periods of the A-V node overlapped before and after autonomic blockade. Supraventricular tachycardia in Lown-Ganong-Levine syndrome: intranodal versus antinodal reentry. As discussed, there are two predominant groups of patients, based on mechanism of the short P-R interval. Details of studies that can demonstrate “upper and lower final common pathways” are given in Chapter 8. Heterogeneous retrograde 92 93 atrial activation patterns are seen in these patients as in those with normal A-V nodal conduction. This is not surprising because the major determinant of cycle length of A-V nodal reentry is conduction down the slow pathway. In our experience, the slow-pathway conduction times and refractoriness in patients with normal and short P-R intervals are indistinguishable. On the other hand, the fast pathway in such patients is faster than in patients with normal P-R intervals; the A-Hs are shorter in sinus rhythm, 143 and capability for retrograde conduction over the fast pathway is greater. Thus, the Lown–Ganong–Levine syndrome may merely reflect a bias caused by the characteristics of the fast pathway. The bulk of evidence suggests that the fast pathway is composed of A-V nodal tissue but has more rapid 14 136 conduction and shorter refractory periods. Thus, these patients appear to represent just one part of the spectrum of patients with A-V nodal reentry and normal P-R intervals. In contrast, the cycle length of tachycardias using concealed bypass tracts tends to be much shorter in patients with short P-R intervals than in patients with normal P-R intervals. This is not surprising because in patients with concealed bypass tracts antegrade conduction proceeds over the rapidly conducting A-V node, thereby abbreviating that limb of the reentrant circuit. In fact, enhanced A-V nodal conduction and reciprocating tachycardia using concealed bypass tracts should be considered in any individual with paroxysmal reciprocating tachycardias having cycle lengths ≤250 msec. Patients with short P-R intervals that are due to either enhanced A-V nodal conduction or atrio-His bypass tracts may exhibit atrial flutter or fibrillation with a rapid ventricular response. These patients primarily present with atrial fibrillation or flutter and a rapid ventricular response, which may, in fact, induce ventricular fibrillation (Fig. They found the ventricular response to be directly related to the refractory period. Thus, the functional characteristics of the tissue responsible for A-V conduction is the main determinant of the ventricular response P. Of note, in the group of patients with enhanced A-V nodal conduction who demonstrate dual A-V nodal pathways, the ventricular response is slower. This is a result of the fact that block in the fast pathway frequently occurs with conduction over the slow pathway and repetitive concealment into the fast pathway once conduction proceeds over the slow pathway. A: Atrial flutter with 1:1 A-V conduction is present in a patient with an atrio-His bypass tract. B: 200 mg of lidocaine produced block in the bypass tract, resulting in 2:1 conduction down the normal pathway. Because most of the reciprocating tachycardias are due to A-V nodal reentry or reentry using a concealed A-V bypass tract, treatment should be the same as that for patients with normal P-R intervals with these arrhythmias. With the development of deflectable catheters and increased experience, radiofrequency ablation is the therapy of choice for most patients (see Chapter 14). Patients with atrio-His bypass tracts and atrial flutter and fibrillation with rapid ventricular responses require treatment with drugs that can suppress these bypass tracts and/or prevent the arrhythmia. In the case of atrial flutter (either as a primary arrhythmia or one created from atrial fibrillation by drugs) catheter ablation of flutter is possible and is highly successful (see Chapters 9 and 14). Catheter-delivered radiofrequency energy is the current method of choice to create A-V block (see Chapter 14). Accessory Pathways with Anterograde Decremental Conduction and Fasciculoventricular Pathways At the beginning of this chapter, we assigned all the variants of preexcitation syndromes pathophysiologic names as opposed to the eponyms formerly applied. Thus, fibers initially considered under the rubric “Mahaim” fibers are now recognized as atriofascicular, nodofascicular, nodoventricular, and fasciculoventricular bypass tracts. Nodoventricular bypass tracts were initially described by Mahaim and Benatt in 1937 as conducting tissue 148 extending from the A-V node to the ventricular myocardium. Pathologically, fibers have been described from the node to the ventricle and from the fascicle to the ventricle, usually in or adjacent to the septum.
The spacer material is then sewn along the arms should correct lid laxity and maintain a lower lid posi- posterior lamella to physically elevate the lid margin generic rogaine 2 60 ml with visa. If tied too tightly discount rogaine 2 60 ml on line, Materials used can include Enduragen generic rogaine 2 60 ml without prescription, Alloderm cheap 60 ml rogaine 2 mastercard, or autog- clotheslining of the lid below the globe can occur; this is enous ear cartilage. The spacer material is cut to the desired corrected by loosening the suture and stretching the lid supe- height needed for support of the cut lid margin. The freed lid margin is held against the lateral lateral vector to smooth the infraorbital skin. Straight excess at the lateral extent is conservatively marked as a tri- sharp scissors are used to perform a full thickness excision of angle (Fig. The area of redundancy is deepithelialized to the redundant lid, usually measuring 2–4 mm. The same create a lateral pennant of orbicularis muscle that can be double-armed 4-0 Mersilene or Prolene is passed inferiorly anchored to the lateral orbital rim and provide solid suture to superiorly along the cut edge of the tarsal plate. Once ﬁxation of the lower lid during the postoperative healing again, each arm of the suture is passed from deep to superﬁ- phase (Fig. A suture is placed through the muscle and cial along the lateral orbital rim periosteum at the level of the then tacked to the periosteum along the anterior aspect of the midpupillary line and tied to reestablish lid ﬁxation. Any excess muscle is fast absorbing plain is then used to tack the anterior aspect of trimmed. This recreates the natural concavity in the lateral the lower lid gray line to the posterior aspect of the upper lid lid region and acts as an additional means to counteract the gray line in an effort to recreate a sharp lateral canthal angle. Any skin muscle excess along the lid margin itself is of the anterior globe to the inferior orbital rim should be taken also excised with curved sharp scissors, taking care to avoid 770 K. A running 5-0 Prolene is used to close the subciliary and lateral canthotomy incisions. Typically this includes artiﬁcial tears during the day, and a steroid/antibiotic ophthalmic combination ointment at night. Oral steroids, cool compresses, and head elevation are useful to minimize swelling. In addition to the aes- and conservative skin excision minimize complication risk, thetic deformity, these positional changes can lead to dry several other factors alone or in combination can predispose eyes and exposure keratitis. These factors include failure Lower Eyelid Blepharoplasty 771 of the lateral canthal suture ﬁxation, excessive edema or contribute to postoperative lid malposition. A drill hole cantho- proptosis or midface hypoplasia predisposes a patient to this plasty may be necessary. Drill holes are created along the lateral problem due to the inherent imbalance of lower lid support orbital rim and the tarsal plate suture needles may be passed mechanisms. The combination of globe prominence coupled through these for ﬁxation to the bony orbit. With the exception of an expanding hematoma, In cases of lid malposition, a majority of patients will these do not usually require reoperation and can be managed respond to conservative treatment initiated in the early postop- with warm compresses to promote liquefaction and resorp- erative period. Stretching the lower lid hemorrhage is rare with an incidence less than 1 %, but early superiorly against the curve of the globe can also be helpful. Immediate operative inter- quate lid support is essential when performing transcutaneous vention is necessary. Both canthopexy and canthoplasty techniques removal, lateral canthotomy and cantholysis, and control of ﬁx the lateral lid to the periosteum along the inner aspect of active hemorrhage. Orbital bony decompression is a last the lateral orbital rim in an attempt to stabilize lid position. Lateral canthal ﬁxation has proven useful to not only prevent Chemosis refers to a condition in which the conjunctiva lower lid problems but to also correct them when they occur. The edematous conjunctiva prevents Therefore, in cases where lateral canthal ﬁxation was not ini- adequate tear dispersion and a dellen, or corneal dry spot, tially performed or technical failure of the suture is suspected, occurs. The etiology is likely lymphatic drainage obstruction, lateral canthoplasty should be performed. If recognized intraoperatively, leads to skin shortage which can overcome even solid tarso- the conjunctiva can be snipped to decompress the edema. Anterior lamellar postoperative treatment regimen focuses on ocular lubrication deﬁciency from aggressive skin resection can be identiﬁed with a combination of artiﬁcial tears and ointment. If severe or cases respond to stretching exercises, but those that do not persistent, the globe can be anesthetized with topical anesthetic will usually require skin grafting. The presentation of erythema and malposition is not limited to the lateral canthal region and tenderness in the initial weeks following blepharoplasty will includes the central portion of the lower lid. Treatment the scarred structures need to be completely released and the lid with a 7–10 day course of oral antibiotics is appropriate. To maintain adequate support to the lower lid and cor- usually the result of more atypical organisms, namely myco- rect vertical lamellar deﬁciency, a spacer graft must be inserted bacteria. Use of material such as a human be initiated, though clinical resolution can be rather protracted. The presence of redness with will ultimately translate into 1 mm of corrected vertical height. Quality Medical distinction to those cases attributable to an infectious etiology. As is often the case in plastic surgery, the best surgical out- Quality Medical Publishing, St. Plast Reconstr Surg 121(1):241–250 show, and ectropion bear both functional and aesthetic con- 9. Plast Reconstr Surg 92: lize lid position in the setting of lower lid blepharoplasty are 1068–1072 essential to minimizing postoperative complication risk. Plast Reconstr Surg 125(1): 384–392 Blepharoplasty: Minimally Invasive Approach Nicolò Scuderi and Luca A. Dessy 1 Introduction 2 Preoperative Evaluation The orbit and the surrounding tissues constitute the emo- It is always necessary that patients undergo ophthalmic eval- tional and expressive part of the human face. During the ophthalmology visit, it is impor- erative evaluation allows to safely obtain satisfying results. Afterwards, tear secretion is evalu- development of less invasive techniques that offer the advan- ated through the Shirmer’s test and ﬁnally the presence of tage of being easier and faster and that allow to reduce the local infections (blepharitis, chalazion) is ruled out. These minimally invasive techniques allow to to choose the most appropriate technique, the surgeon should obtain natural, effective, long-lasting results with a decrease then evaluate the following characteristics: in risk of complications [1, 2]. This chapter presents the minimally invasive techniques • Quantity and characteristics of palpebral skin: It is of lower blepharoplasty that, when appropriately selected, important to evaluate the skin excess when the patients produce signiﬁcant and effective results reducing the risk of look upwards. The following approaches are described: the the surgeon an idea of how much skin excess is present. If preseptal and retroseptal transconjunctival approach to the the evaluation of the skin excess is performed only with lower eyelid, the treatment of lower eyelid skin excess by the patient looking frontally or downwards, after the skin pinch technique or other ancillary treatments. In this kind of surgical procedure, indeed, the pretarsal presence of pseudoherniation. This evaluation is also bet- portion of the orbicularis oculi muscle is not touched so as to ter performed with the patient looking upwards. In order preserve the shape and function of the eyelid and reduce the to distinguish the fat herniation from the oedema, a light onset of lower eyelid malposition. The herniated fat becomes more promi- nent with pressure, whereas in case of palpebral oedema no change is noticed. Dessy between the lower eyelid and the inferior limbus while the fat protruding in the palpebral bags is eliminated or reposi- patient is looking forward. In normal conditions, there tioned through a direct access route that must not pierce the should be no scleral show below the limbus. The distance between the corneal light subjects: young patients with periorbital fat herniation reﬂex and the lower eyelid is normally 5. In case of slight skin excess, skin rejuvenation indication on how much skin is needed to correct the should be performed by chemical peeling or laser resur- ectropion caused by the deﬁcit of the anterior lamella. In case of heavy skin excess, it is necessary to • Presence of a hypertrophic orbicularis oculi muscle: A associate its removal with a cutaneous ﬂap by the ‘pinch hypertrophic muscle can appear as an evident strip in the blepharoplasty’ or the traditional transcutaneous lower eyelid. This access can also be indicated in patients come back to the normal position is measured. Less than with a high risk of dischromic, hypertrophic or keloid one second (without blinking) is normal. Usually, transconjunctival inferior blepharoplasty is per- • Negative vector: The relationship between the cornea and formed under local anaesthesia.
An assistant 5 mm diameter port is placed 5 cm lateral to the camera port  (Figure 87 order 60 ml rogaine 2 with visa. Technique Once the patient is placed in steep Trendelenburg purchase discount rogaine 2 on line, the robot patient side cart is positioned either between the patient’s legs to align the center of the cart with the patient’s midline (central docking) or aligned alongside the patient for parallel docking buy discount rogaine 2 60 ml on line. Identification of the uterosacral ligaments can be achieved by placing traction on the vaginal apex 1341 with a probe in the vagina when the uterus is not present or by using a uterine manipulator when the uterus is present 60 ml rogaine 2 amex. If the later method is indicated, after the uterus has been completely devitalized and prior to colpotomy, upward pressure is placed on the uterine manipulator to help with the identification of the uterosacral ligaments. The complete pelvic course of the ureter is then identified prior to placing sutures. At this level, the uterosacral ligaments are the furthest from the ureters as they are heading toward S3 and the ureters are clearing the pelvic brim. The distal end of the sutures are then passed through the pubocervical and rectovaginal fascia and then incorporated into the vaginal cuff. The vaginal cuff is then tied down after the completion of the cuff closure with polyglactin sutures. A third row of sutures can be used in the instance of elongated uterosacral ligaments. Again as stated in the laparoscopic section, an intraoperative cystoscopy should be performed prior to removal of the ports. The goal of both procedures is to restore normal anatomical support by suspending the apex of the vagina above the level of the ischial spines toward the level of the sacrum without causing any significant distortion to the vaginal axis . In most cases, removing the offending suture(s) will alleviate any obstruction without consequence as long as the surgeon finds the problem intraoperatively [14,15]. Other potential complications include bowel injury, pelvic abscess, dyspareunia, hemorrhage and in rare cases bladder injury, and exposure of permanent sutures into the vaginal lumen . Outcomes Although multiple studies and meta-analyses have been performed evaluating the long-term success of uterosacral ligament suspension when approached vaginally, there are few studies describing the long- term outcomes associated with the laparoscopic and robotic-assisted approach. However, in this study, the uterus was conserved in the laparoscopic approach . In this series, at 6 months follow-up, there was a 100% objective success rate [18,19]. Contrary to many previous studies, this further suggests that the laparoscopic approach is as effective as the traditional vaginal approach. The laparoscopic and robotic approach to performing uterosacral ligament suspension allows the surgeon to have a more global view to inspect the pelvic cavity. Other advantages include the ability to use pneumoperitoneum to access better surgical planes and the also the accuracy of suture placement to achieve an optimal result . The postoperative advantages of this approach are less blood loss, shorter hospital stays, decreased postoperative pain, and the ability to perform adhesiolysis when necessary to obtain a better anatomical result . Although the procedure has been modified through the years, the same principles of using multiple interrupted permanent sutures to attach mesh to the vagina and elevating this up to the anterior longitudinal ligament at the level of the sacrum are still important today. Lane also describes the importance of reapproximating the peritoneum over the synthetic material to avoid interaction of the graft with other pelvic structures. He further emphasized the importance of using mesh to replace the inadequately supported structures that contribute to prolapse as a disorder . Although the gold standard for treatment of apical prolapse is the abdominal sacrocolpopexy due to its effectiveness and availability around the world, many institutions have adopted the more minimally invasive approaches of laparoscopy and robotic-assisted techniques [17,23,24]. Nezhat in 1994 first introduced the laparoscopic sacrocolpopexy, showing its decrease in operative blood loss and, most importantly, patient recovery time while still producing high success rates . Although there is no strict definition of success for this procedure, we and many other authors define a successful procedure based on both the “clinical cure” and “objective anatomic cure” rates [12,29]. Laparoscopic Approach for Sacrocolpopexy Port Placement Traditionally, four laparoscopic ports are placed in the abdomen. A 10 mm suturing port is placed in the left paramedian region, and two additional 5 mm ports are placed. The first accessory port is placed suprapubically, and the second is placed in the right paramedian region  (Figures 87. Technique To assist with clearly visualizing the vaginal apex, a probe is placed in the vagina. Next, the peritoneum is dissected away from the vaginal apex anteriorly, exposing the full thickness of the vaginal wall. The dissection is continued one-third down the anterior wall and the space between the rectovaginal fascias. The dissection is continued down to the level of the rectal reflection or further down to the level of the perineal body . If an enterocele is encountered, it should be repaired in a site-specific fashion to avoid suture placement near the area of the graft. The peritoneum overlying the sacral promontory is then incised in a longitudinal fashion and extended down to the right paracolic gutter between the ureter and the colon. The presacral adipose tissue can then be carefully dissected away to reveal the anterior longitudinal ligament. The peritoneum on the sidewalls should be freed enough so that the mesh can be easily retroperitonealized at the end of 1344 the procedure . The anterior leaf of the mesh is sutured using approximately six to ten 2-0 permanent, evenly placed sutures beginning distally toward the vaginal apex. The posterior leaf is sutured in a similar fashion through the rectovaginal fascia. Braided sutures have an increased risk of bacterial colonization, biological tissue response with cellular ingrowth, high tissue reactivity, and suture and mesh erosion . Our institution uses the manual tension approach, where a probe is placed in the vagina to assist with the tensioning of the sacral arm of the mesh. The probe is then removed half way out of the vaginal canal for the placement of the sacral promontory sutures. The surgeon can then tie the free end of the mesh to the anterior longitudinal ligament using two #0 permanent sutures. An assistant then palpates the anterior and posterior wall of the vagina to insure that appropriate tension is used prior to the final sutures being placed. It is important to note that the mesh is not placed on increased tension to prevent postoperative pelvic pain and dyspareunia . The peritoneum is then reapproximated to cover the mesh to prevent adhesion or entrapment of the bowel to the mesh. At this time, an intraoperative cystoscopy should be performed to ensure no bladder or ureteral injury . Robotic-Assisted Laparoscopic Approach for Sacrocolpopexy In 2005, our institution transitioned from performing laparoscopic sacrocolpopexy to utilizing the robotic-assisted approach . We felt that the robotic-assisted approach offered better visualization of the anatomical planes, decreased operative time, and allowed us to further dissect the pubocervical and rectovaginal fascial planes to offer more optimal anatomical results [29,31]. If a concomitant hysterectomy procedure is performed, we have found that performing a supracervical hysterectomy decreases the patient’s predisposition to graft erosion at the level of the vaginal cuff . Technique When Uterus Is Present After a supracervical hysterectomy is performed, the anterior cervix may be grasped with a robotic single tooth tenaculum on the third robotic arm. This technique with the tenaculum eliminates the need to place any instrumentation in the vagina for the first part of the procedure (Figure 87. A manual grasper is introduced through the assistant port to grasp the bladder peritoneum to assist with countertraction while dissecting the anterior portion to further expose the vesicovaginal plane. The boundaries of this dissection includes the bladder neck distally and the vaginal sulcus laterally [12,29] (Figure 87. For the posterior dissection, the rectal reflection is identified along with the insertion of the uterosacral ligaments to the cervix. The posterior portion of the cervix is grasped with the tenaculum and pulled anterior toward the symphysis pubis. The peritoneum is then incised in a horizontal fashion between the uterosacral ligaments. Using a combination of sharp and blunt dissection with the monopolar scissors, the posterior vaginal wall is exposed.
This table shows the way in which the values of the variable are distributed among the specified class intervals generic 60 ml rogaine 2 with amex. By consulting it rogaine 2 60 ml discount, we can determine the frequency of occurrence of values within any one of the class intervals shown purchase rogaine 2 online. Relative Frequencies It may be useful at times to know the proportion order genuine rogaine 2, rather than the number, of values falling within a particular class interval. We obtain this information by dividing the number of values in the particular class interval by the total number of values. If, in our example, we wish to know the proportion of values between 50 and 59, inclusive, we divide 70 by 189, obtaining. We may refer to the proportion of values falling within a class interval as the relative frequency of occurrence of values in that interval. This probability of occurrence is also called the experimental probability or the empirical probability. In determining the frequency of values falling within two or more class intervals, we obtain the sum of the number of values falling within the class intervals of interest. Similarly, if we want to know the relative frequency of occurrence of values falling within two or more class intervals, we add the respective relative frequencies. We may sum, or cumulate, the frequencies and relative frequencies to facilitate obtaining information regarding the frequency or relative frequency of values within two or more contiguous class intervals. Suppose that we are interested in the relative frequency of values between 50 and 79. We may use a statistical package to obtain a table similar to that shown in Table 2. The Histogram We may display a frequency distribution (or a relative frequency distribution) graphically in the form of a histogram, which is a special type of bar graph. When we construct a histogram the values of the variable under consideration are represented by the horizontal axis, while the vertical axis has as its scale the frequency (or relative frequency if desired) of occurrence. Above each class interval on the horizontal axis a rectangular bar, or cell, as it is sometimes called, is erected so that the height corresponds to the respective frequency when the class intervals are of equal width. The cells of a histogram must be joined and, to accomplish this, we must take into account the true boundaries of the class intervals to prevent gaps from occurring between the cells of our graph. The level of precision observed in reported data that are measured on a continuous scale indicates some order of rounding. The order of rounding reflects either the reporter’s personal preference or the limitations of the measuring instrument employed. When a frequency distribution is constructed from the data, the class interval limits usually reflect the degree of precision of the raw data. We know, however, that some of the values falling in the second class interval, for example, when measured precisely, would probably be a little less than 40 and some would be a little greater than 49. Considering the underlying continuity of our variable, and assuming that the data were rounded to the nearest whole number, we find it convenient to think of 39. The true limits for each of the class intervals, then, we take to be as shown in Table 2. If we construct a graph using these class limits as the base of our rectangles, no gaps will result, and we will have the histogram shown in Figure 2. We refer to the space enclosed by the boundaries of the histogram as the area of the histogram. Each cell contains a certain proportion of the total area, depending on the frequency. This, as we have learned, is the relative frequency of occurrence of values between 39. From this we see that subareas of the histogram defined by the cells correspond to the frequencies of occurrence of values between the horizontal scale boundaries of the areas. The ratio of a particular subarea to the total area of the histogram is equal to the relative frequency of occurrence of values between the corresponding points on the horizontal axis. The Frequency Polygon A frequency distribution can be portrayed graphically in yet another way by means of a frequency polygon, which is a special kind of line graph. To draw a frequency polygon we first place a dot above the midpoint of each class interval represented on the horizontal axis of a graph like the one shown in Figure 2. The height of a given dot above the horizontal axis corresponds to the frequency of the relevant class interval. Note that the polygon is brought down to the horizontal axis at the ends at points that would be the midpoints if there were an additional cell at each end of the corresponding histogram. The total area under the frequency polygon is equal to the area under the histogram. This figure allows you to see, for the same set of data, the relationship between the two graphic forms. Stem-and-Leaf Displays Another graphical device that is useful for represent- ing quantitative data sets is the stem-and-leaf display. A stem-and-leaf display bears a strong resemblance to a histogram and serves the same purpose. A properly constructed stem-and-leaf display, like a histogram, provides information regarding the range of the data set, shows the location of the highest concentration of measurements, and reveals the presence or absence of symmetry. An advantage of the stem-and-leaf display over the histogram is the fact that it preserves the information contained in the individual measurements. Such information is lost when measurements are assigned to the class intervals of a histogram. As will become apparent, another advantage of stem-and-leaf displays is the fact that they can be constructed during the tallying process, so the intermediate step of preparing an ordered array is eliminated. To construct a stem-and-leaf display we partition each measurement into two parts. The stem consists of one or more of the initial digits of the measurement, and the leaf is composed of one or more of the remaining digits. All partitioned numbers are shown together in a single display; the stems form an ordered column with the smallest stem at the top and the largest at the bottom. We include in the stem column all stems within the range of the data even when a measurement with that stem is not in the data set. The rows of the display contain the leaves, ordered and listed to the right of their respective stems. When leaves consist of more than one digit, all digits after the first may be deleted. Decimals when present in the original data are omitted in the stem-and-leaf display. As a rule they are not suitable for use in annual reports or other communications aimed at the general public. They are primarily of value in helping researchers and decision makers understand the nature of their data. Solution: Since the measurements are all two-digit numbers, we will have one-digit stems and one-digit leaves. For example, the number 57 on the second line shows that there are 57 observations (or leaves) on that line and the one above it. The number 62 on the fourth line from the top tells us that there are 62 observations on that line and all the ones below. The parentheses mark the line containing the middle observation if the total number of observations is odd or the two middle observations if the total number of observations is even. The line contains only 65 leaves, so the þ indicates that there are five more leaves, the number 9, that are not shown. This is accomplished by making the distance between lines shorter, that is, by decreasing the widths of the class intervals. For the present example, we may use class interval widths of 5, so that the distance between lines is 5. For example, they may be symmetric (the left half is at least approximately a mirror image of the right half), skewed to the left (the frequencies tend to increase as the measurements increase in size), skewed to the right (the frequencies tend to decrease as the measurements increase in size), or U-shaped (the frequencies are high at each end of the distribution and small in the center). One of the demographic variables the researchers collected for all subjects was the Body Mass Index (calculated by dividing weight in kg by the square of the patient’s height in cm). The goal of the study was to compare selenium levels in the region-raised beef to selenium levels in cooked venison, squirrel, and beef from other regions of the United States.