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By P. Hjalte. Meharry Medical College. 2018.

The early popularity of tracheostomies for initial airway management in burn-injured patients gave way to reports of unacceptably high rates of complications purchase 10mg glucotrol xl. In the most often quoted study regarding the risks of tracheostomy in burn patients order glucotrol xl 10mg with visa, Eckhauser et al. Moreover, a 100% correlation was found between cultures of the burn wound and cultures of the endotracheal aspirate. Presence of a tracheostomy stoma, especially through a burn injury, was assumed to facilitate contamination of the respiratory tract with microorganisms from the burn wound. Tracheosto- mies were considered an increased risk in burn patients and a more conservative approach was recommended, with tracheostomies reserved for specific indications rather than for so-called prophylactic airway control [6,7]. More recently many clinicians have published comparisons of clinical out- comes for burn patients managed with translaryngeal endotracheal tubes and tracheostomy tubes. These studies indicate that the risk of pneumonia for patients with tracheostomies is the same as the risk for patients with translaryngeal endo- tracheal tubes [8,9]. The general consensus now is that with current methods of supportive care, the risk of pneumonia appears similar in patients with tracheostomies and those with translaryngeal endotracheal tubes. Tracheostomy offers several advantages over a translaryngeal endotracheal tube in certain patients. For those requiring prolonged mechanical ventilation, the tracheostomy tube has been reported to reduce dead space, improve compli- ance, lower peak inspiratory pressures, and facilitate airway suctioning. Tracheos- tomy also offers protection from laryngeal and tracheal injury. Prolonged transla- ryngeal intubation is associated with laryngeal injury. Tracheostomy is especially beneficial for patients who have sustained inhalation injury to the larynx. Mechan- ical irritation to the larynx by an endotracheal tube exacerbates inhalation injury to the larynx caused by heat or chemical irritants. Several recent studies have described very low rates of morbidity associated with tracheostomy in small study groups of burn patients, especially young pa- tients. Some of these authors have recommended earlier and more aggressive use of tracheostomy in burn patients. A conservative reluctance to use tracheos- tomy in burn patients is now frequently replaced with a broader application of Inhalation Injury 75 this technique, often in patients with normal airways and without need for long- term mechanical ventilation. Reluctance to perform tracheostomy in burn patients may increase risk of laryngeal injury in these patients, especially in those who have also sustained an inhalation injury to the larynx. At the same time, burn patients may experience an increased risk of morbidity when tracheostomy is performed in patients who will not benefit from the procedure (risk without benefit). Many patients who have sustained major burn injury require intubation and mechanical ventilation soon after their injury. For most of these patients, intuba- tion is only required for a short duration, often only until upper airway obstruction due to edema resolves. Even when inhalation injury is diagnosed endoscopically and pulmonary gas exchange is impaired, intubation and mechanical ventilation are not necessary unless there is profound respiratory failure. Under theses cir- cumstances, tracheostomy offers little advantage over a translaryngeal endotra- cheal tube. In fact, in some burn patients initial management with tracheostomy presents an additional serious risk. A specific concern about the use of tracheos- tomy in burn patients is that, soon after burn, pronounced edema from cutaneous neck burns may cause dislodgment of the tracheostomy tube. Under these circum- stances, loss of the airway may be life-threatening. Even in the presence of facial burns, an oral endotracheal tube may be more secure than a tracheostomy when thermal injury to the neck results in extensive edema. One factor contributing to the controversy regarding the timing of conver- sion from translaryngeal intubation to tracheostomy in patients with inhalation injury is that it is very difficult to evaluate accurately the severity of an inhalation injury. This makes it difficult to predict which patients will require prolonged ventilation. The factors that they identified (percentage of body surface area with full-thickness burns, age, presence of inhalation injury, and worst PO2/FiO2 on postburn day 3) were used to develop an equation to predict the probability of prolonged ventilator dependence. Although this equation was found to be sensitive and specific for what they considered for prolonged ventilator dependence, many institutions will not perform tracheostomy at 2 weeks if there is no laryngeal injury and pulmonary function is improving.

At present the most logical approach is to assess the needs of each patient individually and continually through the perioperative period buy discount glucotrol xl 10mg. If preload is opti- mized as described earlier order glucotrol xl 10mg online, then oxygen-carrying capacity can be increased as needed depending on the presence of acidosis or problems with oxygen delivery. Demonstration of acidosis, decreased mixed venous oxygen content, or evidence of myocardial ischemia despite adequate preload and blood pressure suggests a need for more oxygen-carrying capacity. During excision of extensive burn wounds, patients will require transfusion of large amounts of blood, often an exchange volume or more. Massive blood Anesthesia 129 transfusions are associated with a variety of complications, which can be mini- mized but not entirely avoided by careful practice. A variety of techniques have been utilized to decrease surgical blood loss during burn excision. Limb tourniquets or compressive dressings at sites of wound excision or skin harvest help to minimize bleeding. Some centers use epinephrine- soaked dressings or topical epinephrine spray to induce local vasoconstriction. Epinephrine solution can also be injected subcutaneously or beneath the burn eschar. The epinephrine solutions appear to be well tolerated but the effectiveness of these maneuvers is uncertain. Another method is to spray topical thrombin solution (1000 U/ml) on bleeding surfaces before application of compressive dressings. Despite all these interventions, blood loss during extensive excisions is still prodigious. Coagulopathy is one of the more prominent complications associated with massive blood transfusion. Packed red blood cell preparations (PRBCs) are essentially devoid of platelets and whole blood stored for more than 24 h does not possess significant numbers of functional platelets. Whole blood contains essentially normal levels of coagulation factors, with the exception of the volatile factors V and VIII. Because most plasma is removed from PRBCs, they provide a poor source of coagulation factors. Massive blood loss and transfusion with PRBCs or whole blood results in dilutional losses of both platelets and factors V and VIII. Thrombocytopenia is the most common cause of nonsurgical bleeding after massive blood transfusion. In general, 2–4 blood volumes of blood or PRBCs must be transfused before bleeding due to thrombocytopenia will develop. Ob- served platelet counts usually remain higher than calculated values due to release of platelets from sites of sequestration. Bleeding due to thrombocytopenia usually develops when the platelet count drops below 50,000 platelets/ l. Replacement of platelets in adults usually requires transfusion of 6 units of whole blood platelets or 1 unit of single donor platelets in adults. Development of coagulopathy due to depletion of coagulation factors is also possible during massive blood transfusion. Significant prolongation of the prothrombin (PT) and partial thromboplastin time (PTT) can result after transfu- sion of 10–12 units of packed red blood cells. In general, fresh frozen plasma should be given to correct dilutional coagulopathy if the PT and PTT exceed 1. It is also important to know the fibrinogen level in massively transfused patients, since hypofibrinogenemia can also result in prolongation of the PT and PTT. Citrate toxicity is possible with rapid infusion of large volumes of blood products. Citrate is universally used as an anticoagulant in the storage of blood because of its ability to bind calcium that is required for activation of the coagula- tion cascade. Patients with normal liver and kidney function are able to respond to a large 130 Woodson citrate load much better than patients with hepatic or renal insufficiency.

The main differences are due to their smaller overall size and the site of insertion into bone discount 10 mg glucotrol xl with mastercard. They are anisotro- structures which join two or more articular bone pic structures glucotrol xl 10 mg with visa, which means that they may appear ends. Some ligaments, such as the anterior shoul- hypoechoic when the US beam is not precisely per- der ligaments, are embedded in the joint capsule pendicular to their long axis. This is because the Ultrasonography of Tendons and Ligaments 41 incident US will not be reflected back to the probe ficult to avoid. Its effects may be minimized only by unless it is exactly at 90° to the tendon fibrils. Nevertheless, where fibres and the ossified bone decreases with increas- tendons wind around bony surfaces and joints, for ing patient age (Fig. One should not misinter- example around the ankle, anisotropy can be dif- pret the irregular shape of the ossification centre Fig. Normal US appearance of the Achilles tendon in (a) a 1-year-old infant, (b) a 5-year-old child, and (c) an adult. In the infant (a), the Achilles tendon appears as a regular hyperechoic structure (arrowheads) that inserts onto the posterior aspect of the calcaneus (C). Note that the unossified distal epiphysis of the tibia (E), the posterior tuberosity of the talus (T) and the calcaneus (C) are hypoechoic relative to adjacent soft-tissues, and contain fine-speckled echoes. In the child (b), the developing ossification centre of the calcaneus (C) can be appreciated as a hyperechoic structure covered by a layer of unossified cartilage (asterisks). In the adult (c), the Achilles tendon (arrowheads) attaches directly onto the ossified calcaneus (C). In all sonograms, the tendon has well-defined margins anteriorly and posteriorly and exhibits the same fibrillar echotexture made up of many parallel hyperechoic lines due to a series of specular reflections at the boundaries of collagen bundles and endotendineum septa 42 M. Fat-suppres- The sonographic appearance of ligaments is simi- sion techniques, such as fat-saturated fast spin echo lar to those of tendons. Ligaments appear as hyper- (SE) T2-weighted sequences (long TR/long TE) and echoic bands with internal fibrils that join unossified fast short tau inversion recovery (fast-STIR) tech- hypoechoic epiphyses of adjacent bones (Fig. Bilateral examina- sequence, fast-STIR has the advantage that it not tion and careful study of the ligament in different affected by susceptibility artefacts, thus providing scanning planes may be helpful in avoiding misdi- a more uniform fat suppression. Examination of ligaments should be per- the fat-suppressed fast SE T2-weighted sequence formed at rest and during graded application of stress gives better anatomic definition and contrast-to- to the underlying joint. As in adult imaging, con- images of the opposite limb may help confirm the trast-enhanced sequences are useful in the examina- presence of an abnormality on the symptomatic side. MR studies should be performed with the small- est coil that fits tightly around the body part being 3. In general, a flexible surface coil is better MR Imaging than an adult head or knee coil for examination of tendon and ligament lesions in the extremities of MR imaging of tendon and ligaments in children infants and small children. Immobilization of the and adolescents is performed with the same proto- limb can be achieved with a combination of tape, col of pulse sequences used in adults. Images are obtained in sequences (short TE/short TR) are used to obtain the the two orthogonal planes for the structure to be Fig. In the knee (a), the medial collateral ligament (arrow- heads) appears as a thin anisotropic band that overlies the internal aspect of the knee connecting the medial femoral condyle with the tibial epiphysis (E). Deep to the ligament the medial meniscus (arrow) appears as a hyperechoic triangular structure. In the ankle (b), the anterior talofibular ligament (arrowheads) appears as a tight hyperechoic band that joins the talus and the fibula Ultrasonography of Tendons and Ligaments 43 examined, longitudinal and axial to the tendon or 3. High-resolution matrices (512 or 1024) Overuse Injuries and thin slices (1 to 3 mm) with minimal interslice gaps are optimum. For children of 1 year of age or Overuse injuries are the consequence of exceed- younger, oral chloral hydrate (50 mg/kg) is used ing the ability of tendon insertion to recover from for sedation. When the child is older than 6 years, submaximal cyclic loading in tension, compression, sedation is unnecessary in most cases. Monitoring shear or torsion, and depend on a variety of factors, the sedated child during the examination by staff including tissue strength, joint size, and the patient’s trained in anaesthesia with equipment safe for use age and skeletal maturity. Some tendons with a curvilinear course site involved is the knee, with injury to the inser- may exhibit focal signal changes caused by tissue tions of the patellar tendon, either the anterior tibial anisotropy when their fibres run at 55° with respect apophysis (Osgood-Schlatter disease) or the lower to the magnetic field (magic-angle effect).