By Y. Flint. Marlboro College Graduate Center.

It is essential to ob- respiratory drive generic diovan 160mg overnight delivery prehypertension causes, not the inspired oxygen concen- tain a specimen of sputum for microbiological tration purchase 80 mg diovan blood pressure extremely low. If there are serious concerns regarding a se- examination and antibiotic-sensitivity testing, verely hypoxic patient with chronic respiratory ideally from the lower respiratory tract. Bron- disease and a suspected hypoxic ventilatory drive, chodilators may be useful in patients with bron- immediate referral to an expert is advised. Bronchodilators are >40% for a prolonged period, it is both illogical and commonly administered as a nebulized mist di- dangerous to withhold higher concentrations in rectly to the respiratory tract (e. Although it is obvious that these and upper airways is important as nearly all criti- patients would die without mechanical ventila- cally ill patients, whether sedated and paralysed or tion, in recent years it has become increasingly ap- not, are incapable of coughing effectively because parent that mechanical ventilation itself may of generalized muscle weakness. There is now good evidence that limiting inflation pressures by accepting lower tidal The rationale for vasodilator therapy is that the volumes (e. Pulmonary arterioles associated with 15cmH2O) also helps to minimize the extent of poorly ventilated alveoli remain unaffected. Intravenous amiodarone is the most effec- Prone ventilation of patients tive drug used to treat atrial fibrillation in critically The potential benefits of this technique are derived ill patients, and acts either by reducing the from the fact that prolonged adoption of the ventricular response rate or by pharmacological supine posture leads to collapse of dependent cardioversion back into sinus rhythm. Turning vasoconstricts systemic arterioles) is necessary, for patients prone is potentially hazardous and may example noradrenaline. However, majority of patients who benefit from these drugs when undertaken by teams of doctors and nurses have usually suffered a myocardial infarction. The use of inotropes and vasopressors require in- vasive monitoring of the cardiovascular system to Cardiovascular failure direct therapy. Lac- • Correcting hypovolaemia with fluid challenges tic acid is produced by anaerobic metabolism and Increasing left ventricular preload so that it is trends in serum lactate concentration can provide functioning at the peak of the Frank–Starling useful information on whether or not oxygen de- curve. This first step is the single most impor- livery to the tissues and oxygen consumption by tant prerequisite for optimal cardiovascular the tissues is adequate. On the neously when the patient is adequately fluid resus- other hand, younger patients may tolerate a lower 134 Recognition and management of the critically ill patient Chapter 5 pressure. Until relatively recently, it was quite commonplace to attempt to drive the cardiac output to the maximum attain- able using a combination of fluid loading and inotropic support. However, most intensivists now adopt a more conservative approach, following evidence that driving the cardiovascular system towards ‘supranormal goals’ did not improve mortality and could even increase it. Accordingly, when cardiac output is measured, values at the upper end of normal or moderately above it are ac- cepted as satisfactory, taken in the overall context of a stable or improving clinical situation. Acute renal failure Critically ill patients who have acute renal failure as a component of their multiple organ failure have significantly different requirements in terms of renal support from patients with isolated acute or chronic renal failure. An inherently unstable cardiovascular system, the need for continued in- fusion of large volumes of fluid to combat the ex- travasation of circulating volume through leaky capillaries and the use of potent inotropic and va- Figure 5. The vertical, central struc- sopressor drugs mean that these patients are often ture is the filter/dialysis membrane. There are four pumps: bottom right pumps blood in from a central vein into the fil- unable to tolerate the rapid fluid and ionic shifts ter; bottom left pumps fresh dialysate fluid into the filter; associated with intermittent haemodialysis tech- top left pumps out effluent from the filter (consisting of niques, which may precipitate cardiovascular col- dialysate fluid plus ultrafiltrate); and top right pump delivers lapse. Peritoneal dialysis is also of limited value in replacement fluid to the patient to maintain fluid balance. An extracorporeal circulation imum creatinine clearance obtained is much less is set up, containing a filter with an artificial semi- than that during haemodialysis. The problem is that the host response becomes amplified and uncon- week) episodes of standard haemodialysis. How- trolled, contributing to further tissue damage and ever, as alluded to above, this disadvantage is also dysfunction. This them, they describe subtly different clinical may require repeated blood cultures and analysis conditions. Such patients do not recover if surgical bacterial products that may be released into the drainage is not undertaken. However, it is possible that ad- causes include major trauma, burns and acute vances in this area may be made as further research pancreatitis. Elsewhere, severe sepsis due to both excessive consumption oxygen delivery to cells is compromised by shunt- and reduced activation, and the size of the decrease ing of blood away from capillary beds through ar- correlates with mortality. Consequently, micro- teriovenous channels that open in response to the thrombi develop throughout the circulation in inflammatory response. Oxygen consumption by sepsis syndrome and this is one of the main causes cells may also be reduced as a consequence of in- of end-organ dysfunction.

Because their connection to the nasal cavity is located high on their medial wall buy generic diovan 40mg on line blood pressure medication memory loss, they are difficult to drain purchase 40 mg diovan hypertension cardiovascular disease. It is located within the body of the sphenoid bone, just anterior and inferior to the sella turcica, thus making it the most posterior of the paranasal sinuses. The lateral aspects of the ethmoid bone contain multiple small spaces separated by very thin bony walls. These are located on both sides of the ethmoid bone, between the upper nasal cavity and medial orbit, just behind the superior nasal conchae. The largest are the maxillary sinuses, located in the right and left maxillary bones below the orbits. The most posterior is the sphenoid sinus, located in the body of the sphenoid bone, under the sella turcica. The ethmoid air cells are multiple small spaces located in the right and left sides of the ethmoid bone, between the medial wall of the orbit and lateral wall of the upper nasal cavity. Hyoid Bone The hyoid bone is an independent bone that does not contact any other bone and thus is not part of the skull (Figure 7. It is a small U-shaped bone located in the upper neck near the level of the inferior mandible, with the tips of the “U” pointing posteriorly. The hyoid serves as the base for the tongue above, and is attached to the larynx below and the pharynx posteriorly. The hyoid is held in position by a series of small muscles that attach to it either from above or below. Movements of the hyoid are coordinated with movements of the tongue, larynx, and pharynx during swallowing and speaking. It consists of a sequence of vertebrae (singular = vertebra), each of which is separated and united by an intervertebral disc. The vertebrae are divided into three regions: cervical C1–C7 vertebrae, thoracic T1–T12 vertebrae, and lumbar L1–L5 vertebrae. The vertebral column is curved, with two primary curvatures (thoracic and sacrococcygeal curves) and two secondary curvatures (cervical and lumbar curves). Regions of the Vertebral Column The vertebral column originally develops as a series of 33 vertebrae, but this number is eventually reduced to 24 vertebrae, plus the sacrum and coccyx. The vertebral column is subdivided into five regions, with the vertebrae in each area named for that region and numbered in descending order. In the neck, there are seven cervical vertebrae, each designated with the letter “C” followed by its number. The single sacrum, which is also part of the pelvis, is formed by the fusion of five sacral vertebrae. However, the sacral and coccygeal fusions do not start until age 20 and are not completed until middle age. An interesting anatomical fact is that almost all mammals have seven cervical vertebrae, regardless of body size. This means that there are large variations in the size of cervical vertebrae, ranging from the very small cervical vertebrae of a shrew to the greatly elongated vertebrae in the neck of a giraffe. Curvatures of the Vertebral Column The adult vertebral column does not form a straight line, but instead has four curvatures along its length (see Figure 7. When the load on the spine is increased, by carrying a heavy backpack for example, the curvatures increase in depth (become more curved) to accommodate the extra weight. Primary curves are retained from the original fetal curvature, while secondary curvatures develop after birth. In the adult, this fetal curvature is retained in two regions of the vertebral column as the thoracic curve, which involves the thoracic vertebrae, and the sacrococcygeal curve, formed by the sacrum and coccyx. Each of these is thus called a primary curve because they are retained from the original fetal curvature of the vertebral column. The cervical curve of the neck region develops as the infant begins to hold their head upright when sitting. Disorders associated with the curvature of the spine include kyphosis (an excessive posterior curvature of the thoracic region), lordosis (an excessive anterior curvature of the lumbar region), and scoliosis (an abnormal, lateral curvature, accompanied by twisting of the vertebral column).

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Gaps are important in permitting spread of electrical signals from one cell to the next in cardiac and smooth muscle buy diovan 40 mg low price blood pressure monitor. The presence of signaling molecules on the surface membrane of some cells gives them ability to directly link up and interact with certain other cells in a special way cheap diovan 80mg with mastercard arteria faciei. Thus phagocytic cells recognize and selectively destroy only undesirable cell, such as invading microbes while sparing the body’s own cell. Intercellular chemical messenger is the commonest means by which cells communicate with each other. These chemicals messengers are paracrines, neurotransmitters, hormones, and neurohormones. Various ways of cell-to-cell communicaton 34 Signal Transduction Binding on chemical messenger to membrane receptors brings about a wide range of responses in different cells through only a few similar pathways used. Dispersed within the outer surface on the plasma membrane of cell (muscle/ nerve/ gland) are specialized protein receptors that bind with the selected chemical messenger - neurotransmitter, hormone, or neuro-hormone, that are delivered by the blood or a neurotransmitter released from the neuron. The chemical messenger binds with receptor triggering a sequence of intracellular events that ultimately influence/control a particular cellular activity important in the maintenance of homeostasis, such as membrane transport, secretion, metabolism, or contraction. There are wide ranging responses, but there are mainly two ways by which binding of the receptor with extracellular chemical messenger bring about the desired effects. By opening or closing of specific channels in the membrane regulating a particular ion to move in or move out of the cell, or 2. By transferring the signal to an intracellular chemical messenger (the second messenger), which is turn triggers a preprogrammed series of biochemical events within the cell. Neural transmission or communication at synaptic junction using neuro- transmitters. The first chemical messenger binds with receptor on the surface membrane and then issue their orders - “pass it on “process. The first messenger binds to a membrane receptor, that combination serves as a signal for activation of an intracellular second messenger that ultimately relays the order through a series of biochemical intermediaries to specific intracellular proteins that carry out the dictated response, such as changes in cellular metabolism or secretary activities. This mechanism utilized is similar the variability in response depends on the specialization of the cell. Biological control systems have their own complexities and the enormous range and time scale over which they operate. The physiology of the various body systems is inseparable from homeostatic control mechanisms. Many step intracellular chemical events that amplifies a single irritating event is amplified thousands of times. In nervous system, millions of neurons may be involved in as simple act as walking up stairs. Some intracellular regulatory processes operate at the size scale of individual molecules or ions. On the other hand, of the time and size, the development plan of the human body by the endocrine system involves billions of cells, fulfilled on a time scale of decades. Shows consistency of internal environment of the cell Some terms Used in Control System A “System” is a set of components related in such a way as to work as a unit. A “control System” is so arranged as to regulate itself or another system Some terms used in control systems A”system” is a set of components related is such a way as to work as a unit. A “control system” is so arranged as to regulate itself or another system 42 An “input” is the stimulus applied to a control system from a source outside the system so a to produce a specified response from the control system. An “open loop” control system is one in which the control action depends on (is a function of) output. A “negative feedback” system is one in which the control action is a function of output in such a way that the output inhibits the control system A “positive feedback system” is a closed loop control system in which the output accelerates the control system. All negative feedback system has a controlled variable that is the factor (in the case of homeostasis functions) that the system is designed to maintain. All feedback systems, negative or positive, have a sensor element capable of detecting the concentration of the controlled variable; information gained by the sensor is used to determine the output of the controlling system. Therefore, in a feedback system, there is a sensor element, which detects the concentration of the controlled variable; there is a reference input, which defines the proper control level; and there is an error signal, which is a function of the difference between what the sensor senses the controlled variable and what the reference input determines it should be. The magnitude of the error signal and the direction of its deviations (negative or positive) determine the output of the system. Feedback Mechanisms General Properties of Negative Feedback: Homeostasis demands that important physiological parameters, such as pH, body temperature, body fluids volume and composition, and blood pressure must be maintained with an appropriate limits/range.

Component therapy is indicated when specific factor deficiencies are demonstrated buy diovan 40mg without prescription arrhythmia death. Compatibility tests If administrated blood is incompatible with the patients own blood safe 40mg diovan hypertension 30s, life threatening reactions may result. Group-A contains anti-B antibodies, Group-B contains anti-A antibodies, Group-O contains anti-A and anti B antibodies. In some instances when fully cross- matched compatible blood is depleted or unavailable; type specific or O negative blood should be given. Irregular recipient antibodies cannot be detected and extra vascular hemolysis can also occur. Overall, O negative blood, if randomly transfused, has a serologic safety of about 99. Component therapy Treatment of specific hematologic abnormality often requires only a single component of whole blood. Blood banks reduce the whole blood received from donors to a variety of components. The available products include whole blood, red blood cells, white blood cells, platelet concentrates and plasma in several forms. When it is used within 24 hours it is considered fresh, whole blood and after this time it is referred to as stored. In acute massive hemorrhage transfusion with one unit of whole blood raises the recipient’s hematocrite by 3%. Platelet concentrate Platelets are separated from one unit of blood and suspended in a small volume of the original plasma. Cryoprecipitate 0 This is a protein fraction removed from a unit of fresh frozen plasma that is thawed at 4 c. Plasma protein fraction Similar to albumin but contains additional protein molecules. Complications and risks of blood transfusion Hemolytic transfusion reactions Intravascular hemolytic transfusion reactions; are potentially life threatening reactions that can occur by blood transfusion. Pathophysiology During hemolytic transfusion reaction all donor cells hemolyze, leading to hemoglobinemia, hemoglobinuria and renal failure. These reactions also activate the complement system with subsequent release of vasoacative amines causing hypotension. Treatment ƒ Stop transfusion immediately ƒ Administration of fluids and diuresis with mannitol or frusemide ƒ Transfused blood with patients blood sample should be sent for analysis ƒ Sodium bicarbonate may prevent precipitation of hemoglobin in the renal tubules ƒ Steroids may ameliorate the immunologic consequences. Transfusion reactions from mismatches involving the Rh system or minor antibodies usually induce extravascular hemolysis, since these reactions occur slowly, serious complications do not often develop. Non-hemolytic transfusion reaction Non-hemolytic reaction may occur after transfusions. Allergic reaction: occurs in 2-3% of all transfusion and manifests by urticaria and rashes. Other complications: Complications that can occur with massive transfusion include • Citrate toxicity • Acidosis • Hyperkalemia N. B:- As blood transfusion is accompanied by various complications mentioned above, the decision to transfuse should only be made when it is believed to be life saving. What factors determine the need for blood transfusion in patients with chronic blood loss or chronic anemia? But in addition to this, the patient’s pre-operative situation should be well evaluated so as to make the patient able to withstand the stress of surgery. Factors which make the patient high risk for surgery should be controlled as much as possible. Also, the patients’ postoperative course highly depends on the postoperative care given, and anticipation with early diagnosis and management of postoperative complications. General consideration Preoperative evaluation should include a general medical and surgical history, a complete physical examination and laboratory tests. The most important laboratory tests are: • Complete blood count • Blood typing and Rh-factor determination • Urinalysis • Chest x-ray Further laboratory tests should be performed only when indicated by the patients’ medical condition or by the type of surgery to be performed. Patients with heart disease should be considered high-risk surgical candidates and must be fully evaluated. The perioperative monitoring, induction, and maintenance techniques of anesthesia, and post – operative care can be tailored to the specific cardiovascular diseases.

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