By I. Porgan. Bluffton University. 2018.
Total gas concentration in solution = dissolved gas + bound gas + modified gas Dissolved gas: For a given partial pressure cheap viagra vigour 800mg with mastercard, the higher the solubility of gas the higher the concentration in solution order viagra vigour 800 mg. PaO2 (practical pressure of O2 is arterial system) is slightly less than 100 mmHg because of physiological shunt. Physiologic shunt refers to the fraction of pulmonary blood flow that bypasses the alveoli, therefore is not arterialized. If shunt is small, then A-a is small (normal), If abnormal, A-a difference increases. Exactly opposite events occur in the pulmonary capillaries 246 Oxygen transport in the blood: O2 is carried in the blood in two forms. Each subunit contains heme moiety which is iron-binding porphyrin and polypeptide chain (either α or β). Adult Hb (HbA) has α2 β2 (2 of subunits have α chain and 2 have β chain) Each subunit can bind one molecule of O2, a total of 4 molecules of O2 for 1 molecule of Hb. For Hb subunits to bind O2, the iron in heme moieties must 2+) be in ferrous state (Fe Variants of Hb molecule: 3+ Methemoglobin- This is when iron molecule is in ferric (Fe ) state thus doesn’t bind O2. This is a Congenital variant Fetal Hb (HbF): In fetal Hb, the two β chains are replaced by ϒ chains (ϒ2 α2) HbF has higher affinity for O2 than HbA, facilitating O2 movement from mother to fetus. This Hb is replaced with HbA within the first year of life HbS: This is abnormal Hb, where α is normal, but β is abnormal. O2-Hb dissociation curve: Each molecule of Hb binds to 4 molecules of O2, which is 100% saturation. If 3 molecules of O2 bind - 75% saturation If 2 “ “ “ “ - 50% “ if 1 “ “ “ “ - 25% “ 248 Figure 67. Binding first molecule of O2 to a heme group increases the affinity for the second O2 molecule, the second to the third. The graph shown in figure 68 corresponds to 100% saturation and (affinity of Hg for O2 highest). Due to positive coaperativity, affinity of Hb for O2 is the highest, which corresponds to flat portion of curve (figure 68). Changes in the O2-Hb dissociation curve: Shift to the right: Occur when there is decreased affinity of Hb for O2 (see figure. Increases in temperature also cause right shift, and facilitate unloading of oxygen in the tissues. This decrease in affinity causes right shift and facilitates unloading of oxygen in the tissues. This facilitates O2 delivery to the tissues as adaptive mechanism 252 Figure 69 A. By the time blood reaches the venous end of the capillaries Hb is conveniently in its deoxygenated form (i. There is a useful + reciprocal relationship between the buffering of H by deoxyhemoglobin and the Bohr + effect. Thus the H generated from the tissue Co2 causes hemoglobin to release O2 + more readily to the tissues. The frequency of normal, involuntary breathing is controlled by three groups of neurons or brainstem centers. Afferent (sensory) information reaches the medullary inspiratory center Via central and peripheral chemoreceptors and via 259 mechanoreceptor. Efferent (motor) information is sent from inspiratory center to the phrenic nerve, which innervates the diaphram. Inspiration is shortened by inhibition of inspiratory center via the pneumotaxic center (see below) • Expiratory center (see figure 68) is located in the ventral respiratory neurons and is responsible primarily for expiration. Since expiration is normally a passive process, these neurons are inactive during quite breathing. However, during exercise when expiration becomes active, this center is activated • Apneustic Center. Apneusis is an abnormal breathing pattern with prolonged inspiratory gasps, followed by brief expiratory movement. Stimulation of apneustic center in the lower pons excites the inspiratory center in the medulla, prolonging the contraction of the phrenic nerve. Normal breathing rhythm persists in the absence of these centers Cerebral cortex: Commands from the cerebral cortex can temporarily override automatic brainstem centers. The decrease in PaCo2 will produce unconsciousness and person revert to normal breathing pattern. Central chemoreceptors: They are located in the brain stem (ventral surface of medulla) and are important for minute-to-minute control of breathing. Other receptors: Lung stretch receptors: These are mechanoreceptor in smooth muscle of the airways. Joint and muscle receptors: They are located in joints and muscles and detect movement of limbs. Instruction is given to the inspiratory centers to increase breathing rate Irritant receptors: Their location is between epithelial cells lining the airway. They are stimulated by noxious chemicals and particles The response is reflex constriction of bronchial smooth muscles and increase in breathing rate J- Receptors (Juxtacapillery receptors): These receptors are found in the alveolar walls (thus near capillaries). The stimulus is engorgement of pulmonary capillaries with blood and increase in interstitial fluid volume. The response is increase in breathing rate For example, in left heart failure blood “backs up” in pulmonary circulation, and J receptors mediate change in breathing pattern including rapid shallow breathing and dyspnea (difficulty in breathing) General and Cellular nonrespiratory lung function Filtration: filter out small blood clots (small pulmonary emboli) Immunologic: bronchial secretion contains Immuno globulin ( IgA ) Alveolar macrophages are phagocytic and remove bacteria and small particles inhaled by lungs.
It is believed that formation of antibodies against myelin starts the process of the weakening of the nerves purchase viagra vigour 800mg. The causes of the above mentioned reactions are not clear 800mg viagra vigour overnight delivery, although in 50% to 60% patients, viral infections of the throat, stomach or intestines precede the occurrence of A. In some patients the disease is seen occurring after taking the vaccine for rabies, tetanus and polio. Not only this, research shows that a relation of this disease can also be established with particular seasons. In the initial stage of the disease the patient experiences tingling in the feet, cramps, pain, or in many cases the patient may lose balance while walking. Both the legs get affected almost at the same time and as the weakness increases gradually both the legs and hands become completely paralyzed. While drinking water, the water may come out through the nose and there may be difficulty in respiration. The other symptoms of this disease include irregularity of the heartbeats and sometimes there may be low B. The patient remains completely conscious and a few may lose bowel and bladder control, but this happens rarely. Diagnosis of the disease : The primary neurological examination of the patient with the above mentioned symptoms could give important clues indicative of the diagnosis, in which mainly “Tendon Jerk” (the involuntary contraction of a muscle produced by striking the tendon) is destroyed in this disease. Since there is a difference of opinion regarding the indication of steroids like Methyl Prednisolone and A. In the Plasmapheresis therapy, 1500 to 3000 ml blood is taken from the patient’s body at a time and purified. The cells are separated with the help of a cell separator, purified, harmful antibodies are removed and the purified blood is transfused again in the body. This treatment can arrest the progress of the disease, prevent respiratory difficulties and speed up recovery. This medicine is given for S days in a daily dose of approximately 20 to 30 grams (400mg/kg body weight). It can also be given to children as well as heart patients, but the treatment being very expensive ,makes it difficult for many patients to take advantage of this drug. Besides, physiotherapy has been found to be extremely beneficial in this disease and is an important aspect of treatment. In the initial fifteen days if the disease is not progressing and especially there are no respiratory problems, the possibility of complete recovery is greater, though it may take months to get completely cured. Treatment : l If there is any other disease mentioned earlier, it is detected and treated and especially steroids, plasma exchange, azathioprine are used. If required, braces, splints, boots and other such instruments can be used to make life as easy as possible for the patient. In this disease there is an inflammation on the seventh cranial nerve, which largely occurs due to wind, infection or damage in the ears. Sometimes there can be pain behind the ear, extra sounds in the ears and there may be loss of taste in the tongue. If the treatment is commenced immediately, 90% to 95 % patients get completely cured in one to two months. Sometimes the 7th cranial nerves of both sides get affected at the same time, but usually only one side is affected. In some cases the disease persists for a long time or keeps recurring frequently causing facial paralysis again and again. The mainstay of treatment is use of steroids, optimum physiotherapy, proper eye care and use of antiviral agents (like acyclovir in herpes virus infection) and supportive measures. Many types of neuropathies occur in diabetes, the symptoms of which are mentioned below: l Weakening of the nerves causes difficulty in walking, climbing stairs etc. Due to the loss of sensation, even if the footwear comes out of the feet, the patient doesn’t know it, severe pain occurs in the feet or thighs. While having a bath one is unable to tell the difference between hot and cold water, sensation of the palms and soles is decreased. Ulcers on sole develop and if proper foot care and dressings are not done, this can lead to an unfortunate steps of amputation of the foot; which is a common Cx. There are suitable medicines to control the symptoms of neuropathy, which may provide more or less relief. Mycobacterium leprae is the organism that causes leprosy and it mainly damages the sensory nerves causing loss of sensation in the fingers. One is not able to sense injury, the fingers of the hands and feet gradually fall off and the disease starts spreading. This is mainly of two types: (1) Lepromatus leprosy (2) Tuberculoid leprosy in which there is a comparatively less damage to the skin but neurological damage is high. Medicines like dapsone, rifampicin, clofazimine, etc as well as appropriate dressing can control the disease but treatment can continue from 1. Due to lack of complete scientific knowledge, even doctors may not be able to recognize the disease and the diagnosis is delayed. Entrapment Neuropathy : The most common entrapment neuropathy is the carpal tunnel syndrome, in which the median nerve is compressed by the ligament situated below the palm, causing pain and tingling in the palm, which sometimes extends up to the shoulders. If there is no benefit after splinting the wrist or taking steroids for some time, steroids can be injected locally in the wrist at a particular point. Apart from this, compression of various nerves on various locations in their pathway can cause as many as 30 different types of entrapment syndrome. It occurs when the radial nerve is compressed while sleeping which is also known as “Saturday night palsy”.
Unusual clinical forms mothorax cheap viagra vigour 800mg overnight delivery, lung contusion order viagra vigour 800 mg mastercard, and pneumothorax might provide of extrapleural (epipleural) hematoma on the chest x-ray [in the surgeon with a reliable clinical clue that the patient is at German]. Extrapleural hematoma: a discomfort and a transient rise in temperature but has less recognizable complication of central venous pressure monitoring. Extrapleural hematoma following implying greater blood loss, can produce dyspnea or become 13 infraclavicular subclavian vein catheterization [letter]. Left extrapleural of intrathoracic lesions such as neurofibroma if it is found in hemothorax from rupture of the subclavian artery. Pleural complications Primary hemangiopericytoma of the chest wall: a case report [in in lung transplant recipients. Subjects: 418 patients with blunt chest trauma of whom 29 had a fractured sternum (11 with retrosternal haematoma and 18 without) and 389 did not (7 with widened mediastinum and 382 without). Results: Retrosternal haematomas were found adjacent to many fractures and ranged in size from a few mm to 2 cm. There was no signi cant difference in the number of associated lesions between patients with sternal fractures with or without a retrosternal haematoma. Conversely, patients with a widened mediastinum had a higher injury severity score, longer hospital stay (p < 0. Six patients still had pain 1 month after injury of whom two had injury-related long-term disability because of pain. The early mortality in our study was 2/29 in patients with sternal fractures and 1/7 in patients with widened mediastinum. An aggressive approach including early operative reduction is recommended even for a stable fracture to reduce the overhelming pain. Sternal fracture with or without retrosternal heamatoma is not a reliable indicator of cardiac and aortic injuries, while mediastinal widening is still a fairly reliable clue that should indicate further investigation. Key words: sternal fractures, retrosternal hematoma, mediastinal widening, diagnosis, management, morbidity and mortality, cardiac and aortic injuries. One of our main aims Most chest injuries involve soft tissue, the bone cage, was to nd out if the presence of a sternal fracture and the underlying pleura and lung, and chest wall indicates cardiac and aortic injuries and to clarify the injuries make up a half to two thirds of all thoracic difference between a retrosternal haematoma and injuries that require admission to hospital. The age, sex, should suspect and assess any underlying injuries to the mechanism of injury, comorbidity, clinical diagnosis, heart, bronchus, and great vessels. Reports about radiological diagnosis, associated injuries, complica- sternal fractures are almost always contradictory tions, treatment, length of hospital stay, and follow-up (3, 5, 7, 9, 12, 15). Because most of them are chest trauma of whom 29 patients (range 30–92 years, associated with the steering wheel type of injury the mean age 64, 17 women and 12 men) had a fractured mortality rate may be high because of the severity of sternum (11 with retrosternal haematoma and 18 associated cardiovascular injuries. We therefore con- without) and 389 did not (7 with widened mediastinum ducted this retrospective study to look at the incidence, and 382 without). Upper body 7 2 Three patients initially had echocardiograms and one Manubrium 6 3 Lower body 3 1 a transoesophageal echocardiogram and all were Multiple parts 2 1 inconclusive. Two patients had Adjacent to xiphoid 1 0 displacement by one anteroposterior thickness, four cases were displaced by half an anteroposterior thickness, and 22 cases had stable fractures. The retro- coexisting cardiac diseases, but neither of them had sternal haematomas were found adjacent to many of cardiac problems from the sternal fractures. Electro- fractures and ranged from a few mm to 2 cm in size; cardiographic monitoring with estimation of cardiac they were more common in fractures of the body of enzyme activities were done in nine cases. No patients were recorded There was no signi cant difference in the incidence as having aortic injuries. The incidence of suspected of associated lesions between patients with sternal aortic injury and aortography was 7/29, (3 angiograms fractures with or without a retrosternal haematoma. Differences between patients with sternal fractures and retrosternal haematomas and those with a widened mediastinum alone Sternal fracture and retrosternal Widened mediastinum alone haematoma (n = 11) (n = 18) p Value Associated thoracic lesions 1. A lateral sternal radiograph showing a wide overlapping fracture in the body in which the upper segment separation at the synchondrosis. It is worth emphasising that retrosternal haematomas were more common in fractures of the mid-body and manubrium of the sternum (Table I). The presence of such widening is an indication for urgent aortography to rule out the possibility of concurrent major vascular injury (2). The diagnosis in all cases was based on a history of trauma to the sternum in patients wearing seat belts, with pain and local tenderness. These structures are usually transverse and if displaced the upper segment lies behind the lower fragment (Fig. In the past, immersion in cold water was recommended to reduce the fracture by sudden inspiratory movements, but this is of historical interest only (12). In this series one patient developed a big organised The early mortality in our study was 2/29 in patients haematoma over the fracture. The residual symptom with sternal fractures (one patient died on the 13th day during early follow-up of these patients was usually after injury of multiple organ failure, and one patient pain, which was exaggerated by chest movement. Eur J Surg 167 Cardiovascular injuries 247 However, there are some treatments for sternal showed that pain was the major complication but those fractures: analgesics were taken by all patients and authors did not suggest radical solution such as surgical should be tried rst. A retrosternal haematoma Operative reduction and xation can be done by can be differentiated from real mediastinal widening wiring the proximal and distal fragments together with but our observations are clinical and based on only a 2 or 3 heavy wire sutures (Fig. Like others lessen the unnecessary use of angiograms in a stable (11), we advocate early surgical repair when indicated, patient with a traumatic retrosternal haematoma. Our observations themselves are usually benign if not excessively may make selection easier and avoid unnecessary displaced, they are associated with appreciable mor- angiograms. The sternal haematoma was not associated with cardiac and incidence of sternal fractures and the associated aortic injuries, while mediastinal widening is still a mortality seems to increase with age. American College of Surgeons, Committee on Trauma Sternal fracture has been reported to be associated with Advanced trauma life support manual. The a sternal fracture following discharge from the A and E associated head injuries decreased with time from 49% department. Cardiac and vascular sequale of reduced speed limits, legislation about seat belts, safer sternal fractures.
Distal extremity temperature viagra vigour 800 mg free shipping, capillary refill and peripheral pulses suggest the adequacy of tissue perfusion buy 800mg viagra vigour fast delivery. A prolongation of capillary refill greater than 3 - 4 seconds indicates poor systemic perfusion. Changes in the character of murmur or attenuation of a shunt murmur may reflect significant changes in the child’s condition. The child should (frequently) be examined for changes in cardio respiratory status. Cool extremities with normal or rising rectal temperature suggests decreasing and inadequate systemic cardiac output. Before invasive monitoring is planned, the risk-benefit ratio of catheter placement should be considered. Vascular catheters are commonly placed in the operating room, and include central venous catheters, right atrial catheters, left atrial catheters, pulmonary artery catheters, and arterial catheters. Central venous or right atrial catheters provide right-sided filling pressures, as well as information about tricuspid valve function. They enable indirect assessment of cardiac output by providing systemic venous oxygen saturation119, and they provide a site for infusion of pharmacologic agents. Because of their relative safety and extraordinary utility, most cardiac surgery patients will have a central venous/right atrial line. Central venous catheterization can be obtained by percutaneous cannulation of the internal jugular vein or by placing the catheter directly into the right atrial appendage at the time of surgery. Left atrial catheterization provides measurement of pressures in the left side of the heart, information about mitral valve function, and measurement of left atrial desaturation due to right- to-left shunting in the lung. The indications for left atrial catheter placement are abnormal mitral valve function, abnormalities of left ventricular diastolic and/or systolic function, and abnormal lung parenchyma. Left atrial catheter placement carries the serious risk of introduction of air into the systemic arterial circulation. This can be kept to a minimum by careful management of these lines, the use of air filters, and appropriate education of the care team. The recent introduction of intraoperative echocardiography has resulted in a more selective use of left atrial lines. Pulmonary artery catheters should be used in children whose postoperative pulmonary artery pressure is greater than 1/2 systemic arterial pressure and in children who are at a high risk for pulmonary artery hypertension (Table 22-6). Pulmonary artery catheters are placed during surgery through the right ventricular outflow tract and advanced into the main pulmonary artery. Contraindications for pulmonary artery catheter placement are a large right ventricular outflow tract patch or any anatomic condition which will not allow placement of the catheter through a muscle bundle. This is accomplished by optimization of heart rate, preload, afterload, and entropy, and is guided by invasive, non-invasive, and laboratory monitoring. When cardiac output measurement is not available, mixed venous oxygen saturation trends can provide information regarding the adequacy of oxygen delivery. Studies have demonstrated that mixed venous saturations are a reliable and early indicator of cardiovascular dysfunction and failure to measure this may worsen outcomes in some situations. Another indicator of failing oxygen delivery is the development of lactic acidosis. The sequential evaluation of serum lactate levels provides important assessment of the adequacy of oxygen delivery. Lactate levels are usually high immediately after surgery but should decrease to < 2. Metabolic acidosis that is not accompanied by elevated lactate is usually a hyperchloremic metabolic acidosis (non anion gap metabolic acidosis) and generally resolves without treatment. Hematology, thrombosis and hemostasis Postoperative bleeding is the result of inadequate surgical hemostasis or of coagulopathy, either due to residual heparin, to dilutional effects, or to disseminated intravascular coagulation. If bleeding is not corrected after correction of coagulopathy or if the blood loss is greater than 10 cc/kg/hour, surgical bleeding should be considered and exploration strongly considered. Chest tubes and mediastinal drainage tubes must be kept clear and patent if there is ongoing bleeding in order to prevent the occurrence of cardiac tamponade. The onset is 5-10 days after first exposure to heparin and hours to 2-3 days with re-exposure. Use of alternative anticoagulation is imperative in pre-existing or new thrombosis and should be strongly considered for prophylaxis. Argatroban, a hepatically excreted, synthetic anti-thrombin with a t 1/2 of ~ 40-50 minutes, is presently our choice. Normal versus Abnormal Convalescence Convalescence after cardiac surgery may be characterized as normal or abnormal. Normal convalescence is recovery that is expected given the pre-operative state of the patient, the procedure performed, and the expected effects of cardiopulmonary bypass or other interventions. Abnormal convalescence is recovery that is prolonged or unexpected given what is known about the patient and the interventions that have been performed. It may be due to unknown or under appreciated abnormal pre-operative anatomy or physiology, to unexpected complications of bypass, to residual anatomic defects, or to abnormalities in other organ systems such as pneumonia or sepsis. It is crucial to identify abnormal convalescence and to characterize it thoroughly so that appropriate intervention can take place in a timely fashion. Most congenital heart defects are repaired on cardiopulmonary bypass and require a period of time during which the circulation to the heart is interrupted by aortic cross clamping and infusion of cardioplegia. This provides the surgeon with a still, flaccid heart on which to operate, however, the heart may be "ischemic" during this time. Ischemic injury to myocardium, produced (or unable to be prevented) by the protection used for operative repair, can present serious problems in the postoperative period. For the intensive care physician, knowledge of the aortic cross clamp time (ischemic time) and the period of total circulatory arrest is important. These times can be predictive of the degree of postoperative ventricular dysfunction and the amount of support that can be predicted.
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