By Z. Aschnu. University of North Carolina at Greensboro.
It usually occurs sporadically sildalist 120 mg online, but may be inherited with an autosomal dominant pattern in association with distal skeletal myopathy and occasionally a heart block sildalist 120mgmg with mastercard. Cardiac sarcoidosis can present with restrictive cardiomyopathy order sildalist 120mg overnight delivery, but much more commonly it produces a dilated cardiomyopathy phenotype buy cheap sildalist 120mgmg on-line. Associated cardiac manifestations include conduction disease and ventricular tachyarrhythmia. Direct myocardial involvement, usually in the form of diastolic dysfunction, can be underappreciated, particularly when there is concomitant valvular, coronary, and/or pericardial disease. Separating the relative contributions of multiple pathophysiologic mechanisms in a given radiation patient can be challenging. These patients are at risk for suboptimal outcomes after surgery to correct valvular, coronary, or pericardial disease because of their primary restrictive myocardial disease. Metabolic storage diseases are characterized by intracellular deposition of substances within the myocyte, resulting in increased myocardial stiffness. However, when cardiac manifestations occur, the phenotype is usually dilated cardiomyopathy. Gaucher disease is caused by a deficiency in β-glucosidase, which leads to cerebroside deposition into multiple organs (spleen, liver, brain, bone marrow, lymph nodes, and heart). Fabry disease is a lysosomal storage disease caused by a deficiency in α-galactosidase (X-linked, recessive trait). This leads to glycosphingolipid accumulation in the kidney, the skin, and the heart. Echocardiography is the primary imaging modality for evaluating a patient with a clinical syndrome of congestive heart failure. The most commonly used parameter in clinical practice is the Doppler interrogation of the transmitral flow pattern and tissue Doppler evaluation of annular velocity to determine the E/e′ ratio. There are numerous other 2D and Doppler findings that are critical to diagnosis, including chamber size and wall thickness. In sinus rhythm, using pulsed wave Doppler across the mitral inflow tract generates two waves: the early E wave, corresponding to rapid ventricular filling as the mitral valve opens, and the A wave, which reflects atrial contraction. The E-wave deceleration time is the time from peak E inflow velocity to decay to zero. With age, hypertension, or ischemia, the viscoelastic properties of the ventricle decrease, and the E wave decreases in amplitude, has a gentler slope, and has a longer deceleration time. However, multiple other factors can impact the E/A ratio, and recent guidelines have abandoned this as a sensitive measure of diastolic dysfunction. When the deceleration time is < 160 ms and the E/A ratio is > 2, the patient is considered to have grade 3 diastolic dysfunction. Although the transmitral flow pattern is one of the primary ways of evaluating diastolic function, it has several limitations. It can be difficult to differentiate normal diastolic function from the “pseudonormal” pattern of grade 2 diastolic dysfunction, as they both have E/A ratios > 1. The myocardial velocities have three main components: systolic wave (S′), early diastolic wave (e′), and late diastolic wave (a′). In the earliest stages of diastolic dysfunction, the diastolic velocities of annular motion decrease. Normally, the lateral annulus tends to have higher velocities than the septal mitral annulus. Septal e′ < 8 cm/s and/or lateral e′ < 10 cm/s suggests the presence of diastolic dysfunction. Unlike the transmitral flow pattern, there is no “pseudonormalization” pattern with annular velocity, making it easier to differentiate normal from abnormal diastolic function. Unfortunately, there are many patients that fall into the intermediate zone, where E/e′ > 8 but < 15. For these patients, the presence of elevated filling pressure cannot be determined by this method alone. In patients with predominantly exertional symptoms, it may be useful to perform exercise echocardiography to evaluate for the presence of diastolic dysfunction during exercise, particularly when this is not evident at rest. Therefore, Doppler data should be recorded for a period of time following stress to reduce the likelihood of E- and A-wave fusion, which can make the E-wave velocity difficult to interpret. Invasive hemodynamic assessment is not routinely performed but is indicated when noninvasive studies cannot adequately assess filling pressures. Other diastolic parameters, including Tau (τ), the time constant of isovolumic relaxation, are rarely measured in clinical practice. When restrictive cardiomyopathy is considered, detailed hemodynamics may be of greatest value in directing management but are often less helpful in differentiating between possible diagnoses. It can be useful to measure ventricular function, mass, and volumes when echocardiography is not diagnostic. It is also helpful in establishing or excluding specific conditions such as constrictive pericarditis, sarcoidosis, amyloidosis, or hemachromatosis. Endomyocardial biopsy is used in selected circumstances, particularly when there is a high suspicion of a disorder whose diagnosis will profoundly impact management and prognosis. The most common indication in restrictive cardiomyopathy is to evaluate for cardiac amyloidosis. Biopsy in this setting can determine the presence of amyloid as well as differentiate between the different types of amyloid. The yield of endomyocardial biopsy for patchy diseases, such as sarcoidosis, is low. Diuretics should be used for symptomatic treatment of edema and pulmonary congestion. Chronic use of loop diuretics may lead to diuretic resistance; in this scenario, a thiazide- or potassium-sparing diuretic may be used to augment diuresis. For this indication, hydrochlorothiazide (usually 25 to 50 mg, given once or intermittently) is effective within the first day. Patients may also present with significant bowel edema, rendering diuretics with poor oral absorption ineffective. In these patients, torsemide, which has a better oral absorption profile, is a reasonable option. On occasion, the patient may only achieve symptomatic relief after aggressive diuresis, even to the point where the blood urea nitrogen and/or creatinine is at levels higher than baseline values. Candesartan therapy did, however, reduce heart failure hospitalization in comparison to control. The primary endpoint of all-cause mortality and unplanned heart failure hospitalization was not met, but after 1 year, there appeared to be a statistically significant decrease in heart failure hospitalizations in the active treatment arm. In the overall trial, the nebivolol group demonstrated a significant decrease in the primary endpoint of mortality and heart failure mortality. The trial did not show a significant difference in cardiovascular death and unplanned hospitalization between the two groups. There was a nonsignificant trend toward decreased heart failure hospitalizations but an increased trend toward unstable angina hospitalizations in those treated with digoxin. The international trial which enrolled patients from North and South America as well as Eastern Europe showed that spironolactone reduced hospitalizations, but had no effect on the primary outcome of cardiovascular death, aborted cardiac arrest, or heart failure hospitalization. Interestingly, subgroup analysis revealed a significant reduction in the primary outcome in patients enrolled in North and South America, but not those enrolled from Eastern Europe (who were younger and had less diabetes, chronic kidney disease, and atrial fibrillation than North and South American patients). Resting echocardiogram should be performed, with particular attention paid toward the presence of resting diastolic dysfunction. If this is absent, one can consider exercise echocardiography to determine exercise-induced diastolic dysfunction. Even in the presence of this diagnosis, specific treatment or change in management is uncertain. For patients presenting with overt signs of congestive heart failure, echocardiography should be used to narrow the differential diagnosis. In these patients, additional, focused testing should be performed to establish the etiologic diagnosis. Candesartan and spironolactone have been shown to reduce hospitalization in clinical trials. Loop diuretics should be used for symptomatic benefit; they can be combined with thiazide diuretics to treat diuretic-resistant patients.
The fingers (over the joint line) may feel a ‘clunk’ as a femoral condyle passes over a torn meniscus buy sildalist 120mgmg low price. When prone discount sildalist 120mgmg with amex, look and palpate for swelling in the popliteal fossa and proximal calf that may indicate a low lying popliteal cyst 120mg sildalist with mastercard. With the patient lying on their side and affected leg uppermost sildalist 120mgmg without prescription, the leg is abducted and knee flexed to 90°. Holding the hip joint in neutral with slight extension and external rotation, the leg is released. Failure of the knee to adduct/fall is a positive test—leg length inequality and foot over- pronation may be causative factors. Normally the ankle mortise faces 15° externally relative to a sagittal plane axis through the tibial tubercle (arrow) but in medial torsion it faces forward or internally. Specialized radiographic views: tomographic views; ‘skyline’ (axial with knee bent) view; or lateral view taken with at least 30° of flexion • Tomography is useful for clarifying non-peripheral osteochondral defects. Aspiration of joint and periarticular fluid collections • Early aspiration is essential if infection is suspected (see Plate 19). Address biomechanical factors Input from a physical therapist may be helpful in cases of anterior knee pain. Saline irrigation and injections with hyaluronan preparations are also used, but response is variable. Although some studies demonstrate improved pain control and function, other studies indicate that these are no better than placebo. Surgery • Arthroscopy is often used as a diagnostic tool in cases of undiagnosed monoarthritis and to confirm and trim cartilage tears. Y-90 injection can be arranged to follow arthroscopic synovectomy aiming to maximize the effect of both procedures. Knee pain and lower limb development in children and adolescents General considerations In younger children, especially, knee, foot, and ankle problems need assessment in light of developmental stage and with reference to any developmental abnormalities. There is a nighttime predominance, hence the term ‘benign nocturnal pain of childhood’. This is a variable lesion which ranges from mild dynamic imbalance with lateral patellar compression to recurrent patella dislocation and chronic dislocation. Snapping and catching during flexion differentiate it from other biomechanical lesions. Lower limb developmental factors and variations Developmental factors • Developmental characteristics often imply that different age groups are prone to a different spectrum of conditions. Femoral anteversion • This causes internal femoral torsion leading to a medially rotated patella and in-toeing. Internal tibial torsion • This results in in-toeing and is normal in toddlers, resolving at 2–4 years. Genu varum (bow legs) • Bow legs are normal in toddlers and normal beyond 4 years if mild and symmetrical. Genu valgum (knock knees) • Knock knees is physiological between 2 and 6 years of age and does not progress after 7 years. The mechanical axis or centre of gravity (drawn from the centre of the femoral head to the centre of the ankle) should bisect the knee and lie within the intercondylar central area of the knee. Lower leg and foot disorders in adults Anatomy Anatomy of bones and joints • The leg absorbs six times the body weight during weight-bearing. Strong ligaments secure the ankle (formed by tibia above/medially and fibular malleolus laterally) and talocalcaneal (subtalar) joints and bones of the midfoot (Fig. The configuration of bones at synovial articulations allows dorsal flexion (foot pulled up), plantar flexion (to walk on toes), inversion (foot tips in), eversion (foot tips out) and small degrees of adduction and abduction. Anatomy of the long muscles and tendons • In the lower leg, a strong fascia connects the tibia and fibula. Their tendons pass in front of the ankle in synovial sheaths held down by strong retinaculae (Fig. The tibialis anterior, the bulkiest flexor, inserts into the medial midfoot (medial cuneiform). The soleus, which arises in the lower leg, merges with them in the Achilles tendon. Tibialis posterior, the bulkiest plantar flexor, inserts into the plantar surface of the navicular. Anatomy of intrinsic foot structure • Intrinsic foot structures have been greatly modified during evolution to combine provision of a flexible platform for support and a rigid lever for thrusting body weight forward when walking. The latter two muscles arise from the plantar surface of the calcaneum deep to the plantar fascia. Neuroanatomy • The sciatic nerve splits into tibial and common peroneal nerves above the knee. The common peroneal is prone to pressure neuropathy as it runs superficially around the fibular head. A superficial branch supplies the peroneal muscles and most of the skin over the dorsum of the foot. It then passes under the medial flexor retinaculum dividing into medial and lateral plantar nerves, which supply the intrinsic plantar muscles of the foot and skin of the sole. Functional anatomy • In a normal gait pattern, the foot is dorsiflexed and invertors/evertors stabilize the hindfoot for heel strike. As weight is transferred forward, the foot plantar flexes and pronates, the great toe extends (optimally between 65° and 75°), and push off occurs through the medial side of the forefoot. A fall on a pronated inverted foot without direct trauma can result in a fracture of the distal fibula. This is probably a consequence of the relative strength of the talofibular ligaments compared with bone. Conditions of the lower leg • Patients with lower leg conditions present with pain or deformity. These pains are often described by patients as ‘cramps’—suggesting a muscle problem at first. Taking a history from an adult with lower leg or foot pain Ask about site and quality of pain in the lower leg • Localized anterior pain occurs in bony lesions of the anterior tibia, e. An alternative would be vascular claudication where often pain is more overt, and critical ischaemia can give night pain eased by hanging the legs over the side of the bed (gravity effects). Escape of synovial fluid from the knee into the soft tissues of the calf can present with acute pain and swelling and be misdiagnosed as a deep vein thrombosis (pseudothrombophlebitis). Often clinically indistinguishable from Achilles tendonitis or retrocalcaneal bursitis, enthesitis is usually associated with axSpA (see Chapter 8). An os trigonum may become damaged especially in soccer players and ballerinas (see later in section). Mechanical plantar fasciitis is thought to occur more frequently in people who are on their feet for long periods of time, those who are obese, have thin heel fat pads, or poor footwear. Symptoms of arthritis and enthesopathy elsewhere, low back pain (sacroiliitis), eye inflammation (iritis), psoriasis, or previous gut or ‘urethral’ infection, might suggest SpA. Local or diffuse soft tissue inflammation is common and often misdiagnosed as cellulitis. Establish possible causes of forefoot pain • In those with forefoot pain, typically referred to as metatarsalgia, establish whether the condition is focal or due to arthropathy. Although many toes may be affected, dactylitis may be unilateral and affect just one toe. The deformity is associated with altered weight-bearing and a second toe (hammer) deformity. Ask for a description of the pain • As in the hand, neurogenic pain is common and typical. Weakness If true weakness is the major problem rather than pain, the diagnosis is usually between a myopathic process, but more likely is a spinal or peripheral nerve lesion (see ‘Examination’, p. Examination of an adult with lower leg or foot pain Observation Observe the lower legs and feet from front and back, while the patient is standing. Note any swelling, deformities, or rashes: • Lower leg deformities to note: tibia varum (or bow legs) in an older adult may be due to Paget’s disease of the tibia.
High error rates tell a story; they are indicative of a system that either gives rise to order sildalist 120mgmg, or fails to S L E prevent sildalist 120mg line, them purchase 120mg sildalist visa. In other words order sildalist 120 mg with amex, when errors are identifed, it should be appreciated that they are the symptoms and not the disease. L The ‘Swiss Cheese analogy’ is often used to explain how a system that is full of holes (ubiquitous errors, systems failures, etc. S, software (procedures, Standard Operating Procedures adverse environmental circumstance + error + poor equip- Checklists, etc. Error management aims to reduce the total 504 Error, Man and Machine Chapter | 29 | Hazards Organizational failure Inadequate communication Time pressures Poor equipment design Tiredness–lack of vigilance Catastrophic loss Figure 29. As an example the organizational failure may be the expectation of an inadequately trained member of staff to perform a given task. It is Forty years ago, getting on board a commercial aircraft was almost never the only cause and when we focus on ‘who a more risky proposition than it is today and arriving is to blame’ we miss our opportunity to ‘fnd a system safely at your intended destination was not guaranteed. Loss of situational awareness Puerto Vallarta in Mexico for Seattle, Washington, with a 4. Sixteen minutes into the The catalyst event may immediately precede the incident fight the autopilot tripped off, indicating a malfunction or seem unrelated to it: for example a decision is made to of the autopilot or fight control system. What the crew did not know was that when alert the physician about an important drug interaction. Because have contributed to, rather than mitigated the error, the this assembly experienced heavy fight loads, the softer 505 Ward’s Anaesthetic Equipment metal wore at a greater rate than the harder metal, and so instrumentation, there is relatively little going on ‘behind’ the assembly became loose (Catalyst event). Any discrepancies, either between specifc procedures for inspection and lubrication of the instruments or between the instruments and the pilots’ jackscrew assembly. Other airlines, having complied with own mental model, immediately trigger investigation. However, because this process was highly automated fight deck is the tidiness and absence diffcult and time-consuming, the airline had received per- of dials. This construct inspect at intervals of 2300 hours, instead of the 700 hours is becoming increasingly pertinent in modern anaesthetic recommended by the manufacturer. When the airplane workstations with their integral monitoring and auto- was inspected by maintenance a few days earlier, it was mated startup checklists. This complexity is potentially found to be ‘outside of tolerances’, but was overridden by very fragile: a small problem could collapse a whole a line supervisor, and the aircraft was placed back into system and lure the pilot (or anaesthetist) down deceptive service (System faults). Equally, com- Within sight of the airport, and after recovering from a plexity can also provide safeguards that we simply never dive, the crew discussed the diffculties with maintenance. Soft- Unaware of the gravity of the situation, and ignoring the ware programmes are opaque and decision-making has advice of the frst offcer who was urging him to land changed because of it. Perhaps the irony of our relation- immediately, the captain elected to do ‘a little trouble- ship with technology is that the more advanced the shooting’ (Loss of situational awareness and human systems, the more we need the human being to solve all error). Two hours and 42 min into the fight, they lost the problems we unwittingly designed into them in the total control of the aircraft, fying it upside down for 70 s frst place. In aviation, decision-making calls information they receive, be it verbal, computerized, or in for a three-dimensional appreciation of the environment the form of checklists or procedures. If the information is (considered a hostile environment) that is travelling at wrong, or delivered late, the decision and subsequent speeds of up to 500 miles per hour. Decision-making is also depend- pressure that the consequence of error can be catastrophic. The individual can, therefore, attend to only one process The term ‘situational awareness’ describes a dynamic state at a time and, although he can change from one process of (cognitive) awareness that allows for the integration of to another extremely rapidly, the danger of preoccupation information and the use of it to anticipate changes in the is obvious. Every individual has his or her own time and emotion in the decision-making process. This mental attraction of computers to assist in collating information model is informed by culture, training and previous expe- and decision-making is, therefore, evident. But no matter how familiar the territory, an indi- Advancing technology has, in many instances, brought vidual’s perception of a situation may not be the right one increasing complexity in the machinery, whilst at the same and, if left unchallenged, could lead to faulty decisions time seductively simplifying what is seen on screen. Crews are, therefore, taught to instance, in older aircraft, the fight crew are surrounded confer and cross-check their mental models before making by a vast number of dials, bars and indicators that provide assumptions or decisions that give rise to mistakes. They a continuous source of raw data, which they interpret and are thus enhancing their situational awareness and using formulate into a mental model of the aircraft’s position this knowledge to make predictive judgements on the and status. Errors inevitably give rise to more errors, a process that can suck its victim down a root and branch corridor of mistakes literally miles away from the original task at hand. This shows a notable decline in performance trainees) confrmed that there was a higher rate of needle 8 after about 30 min. A study of anaesthesia trainees thesia machines and monitors allow alarm parameters to at Stanford confrmed that chronic fatigue can be as be set for all measured variables; this level of vigilance harmful as acute fatigue. For any task there is In 1943, research by the Royal Air Force showed that vigi- a level of arousal at which one performs most effciently, lance, requiring continuous monitoring and detection of as shown in Fig. Surprisingly, this optimal level brief, low-intensity and infrequently occurring events over decreases as the diffculty of the task increases. However, it is critical in the operating theatre that the anaesthetist is open to receiving input from others, including trainees and others whom he may consider to Optimal be in a subordinate role. Here we will consider the personality types and behaviour patterns that may be error prone. We believe that there are four identifable steps which Drowsiness Fear humans take that lead to adverse events. These we have collectively termed the ‘Shiva factor’, named after the head Total Panic of the Hindu Trimurti, Shiva, who can be both the pre- server of life, and the destroyer. Analyzing the facts to support a decision you have performance for a particular task does not occur at already made maximum arousal. Persisting in a course of action despite a deteriorating condition due to loss of situational awareness. The postcrash investigation revealed that the fight crew had used inappropriate de-icing procedures. His tone of voice that time, although most intensive care medical staff and on the cockpit voice recorder did not convey appropriate pilots were in favour of a fat hierarchy, only 68% of sur- concern about the prevailing conditions (Shiva factor 1) geons favoured this. A fat hierarchy is not the answer to and when his frst offcer questioned him, he was quick to all of our communication diffculties in the operating silence him, attempting to appear as if he had everything room, in fact it is important that decisions are made and under control (Shiva factor 3). In attempts to push back 508 Error, Man and Machine Chapter | 29 | from the gate, the Captain used reverse thrust to aid the Green indicates an optimum situation with all systems tug. The snow, which was blown forward, arises our tendency is to want to go back to green quickly plugged the pitot tubes on the intake of the engines. An example of this in pressures from the pitot system are used to generate an practice is the unanticipated diffcult airway. The fight crew failed to turn on the to try to accomplish that task, especially if we did not engine anti-ice system, which should have prevented the expect it to be diffcult. The frst offcer repeated attempts to intubate the patient may worsen the brought this to the attention of the captain who has the situation resulting in the feared combination of cannot sole authority to reject the take off. They tion attempts and yet anaesthetists still have a tendency to continued the take off at a reduced power setting (because persist in this path (Shiva factor 4). This buys thinking issued the appropriate warnings (no failure of technology) time, so that additional technology may be brought in they failed to push the thrust levers fully up (failure of (diffcult airway equipment), additional profciency may profciency and judgement). That simple action, taken at be added (more/different personnel), guidelines can be the right time, might have averted the disaster. Every critical aspect of fight, and the condi- tions along the way, represents a potential threat that could cause the pilots to err. The details of the fight plan and the reasons behind each deci- sion are fully discussed and understood by everyone. The core purpose of the briefng is to establish a mutual mental model between crew members prior to departure and, equally importantly, to provide the opportunity for any additional information, relevant experience, or even subjective opinion, to be aired and added to the crews’ collective situational awareness. It is recognized here that a steep authority gradient stifes information fow and a ‘superior’ attitude can induce stress and provoke errors in the subordinate. The preparedness consequent to adequate and appropriate planning and briefng affords the crew more mental capacity when variances Figure 29. In aviation, checklists are used in both normal and At particularly crucial phases of fight, i. They may be done individually or landing, the briefng rate increases and the ‘challenge/ in a pair, with one pilot doing and the other confrming response’ use of checklists becomes more critical in error each step.