By Z. Boss. Montana State University College of Technology, Great Falls. 2019.
Te lateral edge is is echocardiographically monitored and then extended for 4–5 cm along the intercostal space tightened the sewing ring ( buy on line cymbalta. Te internal thoracic artery and cross clamp is released and gradually increased vein are isolated and interrupted by applying two pump speed to achieve the desired fow purchase cheapest cymbalta. Te space is better exposed by using a sof Sixth step: Once suspended remifentanil and tissue retractor and rib retractor discount cymbalta 20mg otc. Te activated clotting time target is between in the chest buy cheap cymbalta 60mg line, and the best maneuver to manage it is 180 and 200 s. Te sewing ring is sutured to the to release the pericardium (medial edge) and to myocardium using 8–10 interrupted pledgeted, pull on the pericardium (distal edge) in order to double-armed 3-0 polypropylene sutures. Te cause a twisting of the great vessel axis, shifing sutures are tied to secure the sewing ring. Te cor- the pulmonary artery in a higher plane than the ing knife is inserted through a cruciate incision. In case of driveline management are diferent depending on Jarvik 2000 implantation, once inserted, it is the device. A side-biting bone behind and slightly above the right ear (see clamp is placed on the ascending aorta. Te choice of thesis is cut and anastomosed to the aorta using a positioning the pedestal on the right side is continuous 4-0 polypropylene suture and then detected by major facility of tunneling the power reinforced with BioGlue surgical adhesive. To convey the three-pin connector and tubes and a catheter for continuous fushing with power cable to the skull pedestal site, the incisions saline and antibiotic solution for each access are are made at the frst 1 cm under the clavicle bone positioned. Te patients are usually estal and is implanted frmly onto the external transferred in ward 3–5 postoperative days later. Te reason why usually we prefer a more peripheral surgical approach to the axillary artery is due to steric. Tis is due of the deltoid with the lateral margin of the to its vascular outfow 10 mm diameter. Once dissected skin and subcutaneous devices are provided of larger vascular prosthesis tissue, Beckman retractor is placed to better sizes, therefore not compatible with the size of the expose. Tis leads to exposure of the vascular- nervous structures, covered by sof tissue, which z Subclavicular incision must be thoroughly removed. Te median nerve Trough a 6–8 cm incision below and parallel to is formed in the axilla by two roots from the the lateral two thirds of the clavicle, the axillary medial and lateral cords of brachial plexus. Te incision proceeds deep Generally, the medial root joins with the lateral to the muscle pectoralis major, which is divided in root afer crossing the front of the third part of the direction of its fbers. While is incised secondly, exposing the pectoralis minor, the vein remains anteromedial, the axillary artery which may be divided or retracted laterally. By can be exposed by inferiorly displacing the ner- using a Beckman retractor, the axillary vein is vous block. Nerve structures must always be pre- identifed in its ascending course and once circled served during both artery dissection and vascular is isolated and caudally mobilized. Te artery is axillary artery is obtained with two diferent vas- thereafer dissected from the surrounding tissue. If the axillary artery is larger than 8 mm, (T-anastomosis), using the same we recommend the frst technique (a); contrary, polypropylene suture. A restrictive suture in case of axillary diameter less than 8 mm, we armed with two pledgets is then placed on recommend the second technique (b): the distal portion of the vessel to avoid (a) Afer positioning the vascular clamp axillary overfow. Te proximal portion contemporary monitoring of the arterial of the axillary artery is then anastomosed to pressure in both the radial arteries. Aferward the the axillary artery, it must be tunnelized within distal portion of the axillary artery is the chest through the frst intercostal space. A restrictive tissues, we kindly displace the muscle pectoralis anastomosis is performed with the aim to major and thus expose the frst intercostal space. In addition, in order to create a lung, a 2 cm intercostal space dissection is per- preferential centripetal fow, the selected site formed with particular attention to hemostasis. Another string these cases, we prefer to interpose a vascular guide is tied to the outfow graf prosthesis and is prosthesis of 8 mm in diameter and almost slipped from the frst intercostal space, through 2 cm long, like a Dacron bridge along the the armed vascular prosthesis, out to the ffh course of the axillary artery. Afer checking the hemostasis of Tird step: Te driveline is tunneled subcuta- these two sutures through the release of the neously to the exit point at the lef lower abdomi- clamps, we proceed, afer vessel re-clamp, nal quadrant and thereafer re-tunneled to exit its with an incision of the vascular prosthesis tip contralaterally at the right lower abdominal just interposed, along the long axis of the quadrant. Te rhyme of the incision on the Fourth step: (See the Fourth step of the previous vascular prosthesis is enlarged by removing procedure. Two drainage surgery may compromise the postoperative 24 tubes and a catheter for continuous fushing with course [41, 42]. Performing the procedure using an of-pump Eighth step: (See the Eighth step of the previous technique might reduce the release of infamma- procedure. Additionally, the reduced need for heparin infusion favors a limited intraoperative and postoperative bleeding 24. Given the shortage of valid organs available, an As far as the mini-surgical access concerns, increasing number of patients refractory to max- there is a growing trend toward the use of non- imum medical therapy are treated with mechani- sternotomy incisions and/or mini-thoracotomy cal circulatory assistance, frequently requiring in all felds of cardiac surgery. Additionally, these median sternotomy provides the best access to the patients ofen present very poor general condi- heart and the adjacent structures, it could be tion that frequently leads to a challenging emer- replaced by smaller incisions in most cases. Te gent heart transplant, when an organ is available, choice of our approaches is directed by the possi- because of high risk of acute graf failure or to bility of a good exposure of the great vessels while waiting list exclusion. On the other arrhythmias and hemodynamic instability related hand, given the frailty of these patients, an to the heart manipulation, mandatory when in impairment of hemodynamic, pulmonary, and full sternotomy. Additionally, the surgical risk of a renal function is frequently observed [35–37]. Finally, less extensive medias- achieve a patient with the best possible condi- tinal dissection reduces the risk and the degree of tions when scheduled to receive a new organ. As a matter of fact, the when prolonged mechanical ventilation is entrapment to bed would lead to inevitable con- required, the cerebral perfusion and oxygenation sequent loss of muscle mass, which compromises are compromised. In order to improve the patient respiratory mechanics and prolonged wound management, paravertebral analgesia has been healing. Additionally, several factors related to used in addition to a mild general anesthesia. Casarotto D, Bottio T, Gambino A, Testolin L, Gerosa G rate (pulmonary, renal, gastrointestinal, and (2003) The last to die is hope: prolonged mechanical hemodynamic). Tis analgesia does not infuence circulatory support with a Novacor left ventricular the hemodynamic stability and permits a mild assist device as a bridge to transplantation. Krabatsch T, Potapov E, Stepanenko A et al (2011) Tese maneuvers allow an entire low blood Biventricular circulatory support with two miniatur- transfusion entity procedure, an important issue ized implantable assist devices. Circulation considering patients’ bridge to transplantation, 124:S179–S186 and therefore an eventual immunization should 11. Furthermore, the optimal altered three months and one year following cardiac thoracotomy pain control ofered by the continu- surgery. Toda K, Fujita T, Kobayashi J, Shimahara Y, Kitamura S, Bottio T (2013) Less invasive surgical and perfusion Seguchi O et al (2012) Impact of preoperative percuta- technique for implantation of the Jarvik 2000 left ven- neous cardiopulmonary support on outcome following tricular assist device. Bortolussi G, Lika A, Bejko J, Gallo M, Tarzia V, Gerosa G, 76:88–95 Bottio T (2015) Left ventricular assist device end-to- 4. Ann Thorac Surg 100:e93–e95 use of a left ventricular assist device for end-stage 19. Int J Artif Organs 38:468–470 tality after short-term ventricular assist device place- 20. Ann Thorac Surg 92:1608–1612 Bottio T (2015) Minimally invasive surgical Jarvik 2000 of- 6. Multimed Man Cardiothorac Surg of long-term implantable ventricular assist devices 25;2015. Bottio T, Bejko J, Guariento A, Tarzia V, Pittarello D, Gerosa Lung Transplant 27:718–721 G (2016) Bilateral mini-thoracotomy of-pump Jarvik 7. J Cardiovasc Med (Hagerstown) 17:160–164 publicity campaign to increase commitment to organ 22. Bottio T, Bejko J, Tarzia V, Gerosa G (2014) HeartWare donation on the driver’s license in New South Wales. Clin J Am Soc Nephrol assist device implantation in regional paravertebral 8:484–496 analgesia. Ragnarsdóttir M, KristjAnsdóttir A, Ingvarsdóttir I, Sunami H et al (2013) A heart transplant candidate Hannesson P, Torfason B, Cahalin L (2004) Short-term with severe pulmonary hypertension and extremely changes in pulmonary function and respiratory move- high pulmonary vascular resistance. Int J Cardiol vertebral block for fast-track anesthesia after cardiac 13:S0167–S5273 surgery via thoracotomy. Fülster S, Tacke M, Sandek A, Ebner N, Tschöpe C, 25:205–206 Doehner W et al (2013) Muscle wasting in patients 29. Bottio T, Bisleri G, Piccoli P, Negri A, Manzato A, ment of neurocognitive function after coronary-artery Muneretto C (2007) Heart valve surgery in a very high- bypass surgery.
Lars rections buy on line cymbalta, beam weights order 20mg cymbalta with mastercard, wedges buy cheap cymbalta 30 mg, blocks cheap 60mg cymbalta mastercard, and margins, and Leksell,9 neurosurgeon at the Karolinska Institute in Stock- then computing and displaying dose distributions to assess holm, Sweden, conceived the concept of stereotactic radio- whether the treatment plan will lead to an acceptable out- surgery in 1951. His goal was to develop a method for the come, they do the opposite or “inverse” treatment planning. Sophisti- sell10 coupled stereotactic localization with the delivery of a cated algorithms of the inverse treatment planning system large, single-fraction dose of ionizing radiation. Hundreds to thou- tance and has become an integral part of both neurosurgery sands of small, modulated radiation beams strike a tumor and radiation oncology. Advances in neuroimaging and im- site with varying intensities, and from many angles, to at- proved computer software have made radiosurgery safer tack the target in a complete 3D manner. A comparison of and more efective in the management of a wide range of linear accelerator–based radiosurgery, fxed noncoplanar disorders afecting the nervous system. In contrast to conven- Typically, the patient receives fve treatments a week, one tional fractionated radiation therapy, radiosurgery does not a day, Monday through Friday. Along with these daily treat- rely on the increased radiation sensitivity of the target com- ments, most centers utilizing stereotactic radiotherapy also pared with the normal brain. During this Most conventional fractionation schedules are delivered process gamma photons are released with energies of 1. The emitted photons are precisely directed 25 Stereotactic Radiosurgery and Fractionated Radiation for Pituitary Tumors 265 Fig. The tumor mar- through circular channels drilled into a high-density metal to control movements of the patient’s head and the ter- helmet. Secondary collimation is accomplished through tiary collimators (5 to 35 mm diameter) independent of eight sectors containing 4-, 8-, and 16-mm openings, as potential variations in gantry or treatment couch align- well as a closed position. The majority of targets are treated at the 70 to 80% arranging the size of the diferent sector openings; one or isodose line. Isocenter coordinates, beam openings, CyberKnife and relative weighting of each isocenter are entered into the treatment-planning computer. The Cyber- robotically controlled, repositioning the patient at each iso- Knife has a compact, lightweight linear accelerator mounted center by digitally transferred information from the opera- on a robotic arm. The system has dynamic ented irradiation arcs are delivered using a wide range of tracking software that can follow lesions in six dimensions circular collimators. Detection of mechanical inaccuracy is (three translational and three rotational axes) to account performed by a phantom-target flm technique for every and compensate for any patient movement. The majority of 266 Endoscopic Pituitary Surgery targets are treated at the 70 to 80% isodose line. A complete patient evaluation is essential before initiating Group 1 patients (n = 76) underwent immediate postopera- radiation therapy or stereotactic radiosurgery for patients tive radiotherapy, whereas group 2 (n = 28) patients were with pituitary adenomas. Critical in the decision-making tancy for the two groups did not difer from each other or process are the size and location of the tumor, especially in from that for the general population. In our practice, patients with a clearly marked improvement in tumor control without additional defned tumor that does not directly involve the optic ap- negative efect on pituitary function. In the absence of class paratus typically undergo radiosurgery, whereas patients 1 data, either approach can be supported based on the avail- with poorly defned tumors, or those with compression of able information. Nonetheless, it is reasonable to state that the optic structures, are generally considered better suited patients who have a clearly defnable tumor mass follow- to stereotactic radiotherapy. Moreover, patients with new or ing surgery and who have a life expectancy greater than 10 progressive visual feld defcits in the setting of an enlarging years will likely require additional tumor-directed therapy. Two patients (3%) developed radiation-related well as the remaining functioning pituitary gland. Improved optic neuropathy and four patients (6%) had new pituitary surgical techniques utilizing endoscopy and intraoperative defcits. At a median follow-up of 32 possible for patients with tumors extending into the cavern- months, one patient (1%) sufered a unilateral quadrantopia ous sinuses with acceptable morbidity. Intensity modulated radiotherapy is also tumor after initial surgery remains controversial. Observa- being increasingly used to treat patients with pituitary ad- tion after subtotal resection is frequently recommended enomas. With a median ing exposed to the risks, primarily hypopituitarism, as- follow-up of 43 months, new hormonal supplementation sociated with radiotherapy. The actuarial tumor progression rate at 10 techniques on preserving cognitive function has yet to be years was 2. Two radiation-induced tumors had tumor growth outside the prescribed treatment volume were noted (meningioma and glioblastoma multiforme); and required additional treatment. The risk of de- assessed the risk of secondary brain tumor formation on veloping new anterior pituitary defcits at 5 years was 32%. Overall, 11 patients developed radiation- Other centers have also reported high tumor control rates induced brain tumors in 5749 patient-years of follow-up. The wide range noted in new anterior pituitary def- Radiosurgery of Nonfunctioning Pituitary cits likely relates to length of follow-up and completeness Adenomas 28 of the patients’ endocrine evaluation. Notably, 27% of patients central nervous system malignancies in their patient popu- followed for less than 6 years were considered in remission lation with the national incidence in the United Kingdom compared with 69% of patients who were followed for inter- over the same time frame. Minniti and colleagues32 recently and over 30,000 patient-years of follow-up, they did not fnd reviewed the outcomes of 40 patients with Cushing’s dis- an increased incidence in their radiosurgical patients com- ease who underwent radiation therapy with doses of 45 to pared with the age- and sex-adjusted national cohort. Normalization of cortisol production was seen in 28% primary weakness of this study is the relative short mean of patients at 1 year, 73% at 3 years, and 84% at 10 years. Hypopituitarism the life expectancy of patients having radiosurgery for be- was detected in 62% of patients 5 years after radiotherapy nign conditions. The endocrine results available for radiation therapy of patients with prolactin- secreting tumors are limited. This is no doubt directly related Radiation Therapy of Hormone-Secreting to the success of dopamine agonist therapy in treating these Pituitary Adenomas patients. Consequently, patients undergoing either surgical The goals of treatment for patients with hormone-secret- resection or radiotherapy commonly have large tumors that ing pituitary adenomas are tumor control, endocrine nor- often extend into either one or both cavernous sinuses. For malization, preservation of anterior pituitary function, and such patients, tumor control, rather than biochemical re- minimizing the risk of damage to the optic apparatus and mission, is the most important consideration. Medical therapy and surgical resection had a 10-year tumor control rate of 83% for patients with are the primary methods to normalize hormonal overpro- prolactin-secreting tumors. For these patients, radiation is gener- Radiosurgery of Hormone-Secreting Pituitary ally considered as a salvage technique to stop tumor growth Adenomas and produce biochemical remission. Conventional dose-fractionation schedules and maxi- Stereotactic radiosurgery has emerged as a safe and efective mum radiation doses from 45 to 50 Gy are most commonly treatment for patients with hormone-secreting pituitary used to manage patients with hormone-secreting pituitary adenomas (Fig. Landolt and colleagues38,39 originally adjacent optic apparatus and functioning pituitary tissue. In general, the dose required for tumor control is ers have confrmed that pituitary suppressive medications far less than the dose required for hormonal normalization adversely afect endocrine outcomes. The groups were similar with two studies failed to fnd any association between biochem- regard to irradiated volume, radiation dose, and follow-up. Despite the conficting results, most authors recom- than four times more likely to achieve remission after radio- mend that patients be of pituitary suppressive medications surgery compared with patients with prolactinomas. Such a for several months to maximize the chance of biochemical diferential sensitivity suggests that higher doses should be remission after radiosurgery. Despite early con- Despite the number of patients cured being similar after ra- cerns that 8 Gy was the radiation tolerance of the anterior diosurgery or radiotherapy, the mean interval to remission optic pathways, more recent studies have shown that doses was signifcantly shorter for the radiosurgery group (1. Vladyka et al50 performed outcomes: complete remission was documented in 44% of detailed dosimetric analysis of pituitary adenoma patients patients having radiosurgery and 36% of patients having having radiosurgery at the Hospital Na Homolce, Prague, radiotherapy. Using dose-volume determinations, they signifcantly shorter in the radiosurgery group (26 months) concluded that the primary factor associated with new an- compared with the radiotherapy group (63 months). The terior pituitary defcits was the mean radiation dose to the ability to normalize hormone levels more rapidly makes ra- pituitary gland. In their study, the safe mean pituitary dose diosurgery the preferred radiation management for patients was 15 Gy to maintain gonadotropic and thyrotropic func- with either acromegaly or Cushing’s disease to minimize the tion, and 18 Gy to maintain adrenocorticotropic function. Leenstra et al51 analyzed the dose plans of the 82 patients (secreting tumors, n = 53; nonsecreting tumors, n = 29) and created dose-volume histograms of the identifable pitu- Dose Selection in Radiosurgery of Pituitary itary tissue. The risk of developing new anterior pituitary Adenomas defcits was 16% and 45% at 2 and 5 years, respectively.
Avoiding gastric insufflation requires that peak inspiratory airway pressures stay below esophageal opening pressure purchase cymbalta 40 mg otc. Recommended tidal volumes to cause a noticeable rise in the chest wall in most adults is 0 buy generic cymbalta on line. Each rescue breath should be given over 1 second during a pause in chest compressions cheap generic cymbalta uk. Techniques of Rescue Breathing While maintaining an open airway with the head tilt–jaw lift technique buy 40mg cymbalta overnight delivery, the hand on the forehead pinches the nose, the rescuer takes a normal breath and seals the victim’s mouth with the lips and exhales, watching for the chest to rise, indicating effective ventilation. For exhalation, the rescuer’s mouth is removed from the victim, and the rescuer listens for escaping air while taking a breath. When both hands are being used in the jaw thrust maneuver of opening the airway, the cheek is used to seal the nose. For mouth-to-nose ventilation, the rescuer’s lips surround the nose and the victim’s lips are held closed. In some patients, the mouth must be allowed to open for exhalation with this technique. Give one breath over 1 second, take a normal breath, and give a second breath over 1 second. When there are two rescuers with a child victim, a pause for two breaths should be made after each 15 compressions. Perhaps the most useful adjunct is a common mask, such as that used for anesthesia. The mask can be applied to the face and held in place with the thumbs and index fingers while the other fingers are used to apply jaw thrust. Mouth-to-mask ventilation may be more aesthetic than mouth-to-mouth ventilation and can be just as effective in trained hands. Masks are also available with one-way valves that direct the victim’s exhaled gas away from the rescuer. The self-inflating resuscitation bag and mask are the most common adjuncts used in rescue vehicles and hospitals. Although these devices have the advantages of noncontact and ability to use supplemental oxygen, they have been shown to be difficult for a single rescuer to apply properly to prevent substantial gas leak while maintaining a patent airway. Tidal33 volumes with mouth-to-mouth and mouth-to-mask ventilation are often greater than those with the resuscitation bag. It is now recommended that if this device is to be used, two individuals manage the airway: one to hold the mask and maintain head position and one to squeeze the bag, using both hands. The self-inflating resuscitation bag can also be used with supraglottic34 airways and endotracheal tubes. Tracheal intubation provides the best control of ventilation without concern for gastric distention. With a supraglottic airway or an endotracheal tube in place, breathing can proceed without synchronizing ventilation with chest compressions. Consequently, advanced airway placement should be accomplished without stopping chest compressions, if possible. Following placement, no pause should be made for ventilation, and one ventilation should be delivered every 6 seconds. Studies have not clearly demonstrated that any type of advanced airway management during resuscitation improves outcome over the self- inflating resuscitation bag and mask. Cardiac Pump Mechanism The cardiac pump mechanism was originally proposed by Kouwenhoven et al. According to this theory, pressure on the chest12 37 compresses the heart between the sternum and the spine. Compression raises the pressure in the ventricular chambers, closing the atrioventricular valves and ejecting blood into the lungs and aorta. During the relaxation phase of closed-chest compression, expansion of the thoracic cage causes a subatmospheric intrathoracic pressure, facilitating blood return. Pressure in the 4173 aorta causes aortic valve closure and coronary artery perfusion. During the compression phase, all intrathoracic structures are compressed equally by the rise in intrathoracic pressure caused by sternal depression, forcing blood out of the chest. Backward flow through the venous system is prevented by valves in the subclavian and internal jugular veins and by dynamic compression of the veins at the thoracic outlet by the increased intrathoracic pressure. Thicker, less compressible vessel walls prevent collapse on the arterial side, although arterial collapse will occur if intrathoracic pressure is raised enough. The heart is a passive39 conduit with the atrioventricular valves remaining open during chest compression. Because there is a significant pressure difference between the carotid artery and jugular vein, blood flow to the head is favored. The lack of valves in the inferior vena cava results in less resistance to backward flow, and pressures in the arteries and veins below the diaphragm are nearly equal. This is consistent with the fact that there is little blood flow to organs below the diaphragm. Factors that influence the mechanism probably include the compliance and configuration of the chest wall, size of the heart, force of the sternal compressions, duration of cardiac arrest, and other undiscovered factors. It is likely that the predominant mechanism of blood flow varies from victim to victim and may even change from one mechanism to the the other during the resuscitation of the same victim. Distribution of Blood Flow during Cardiopulmonary Resuscitation Whatever the predominant mechanism, total body blood flow (cardiac output) is reduced from 10% to 33% of normal during experimental closed-chest cardiac massage. Epinephrine improves flow to the brain41 and heart, whereas flow to organs below the diaphragm is unchanged or further reduced. Technique of Closed-chest Compression Cardiac arrest should be assumed in an unresponsive individual with abnormal or absent breathing. The community or institution emergency response system should immediately be activated and chest compressions begun. In emergency circumstances, it is difficult to detect a pulse, even in a major artery (carotid, femoral, axillary). No more than 10 seconds should be taken to check for a pulse and, if a pulse is not definitely felt, chest compressions should be started. Witnessed sudden collapse with unresponsiveness in an adult in the absence of seizure activity is nearly always dysrhythmic cardiac arrest, and chest compressions should be started immediately. Important considerations in performing closed-chest compressions are the position of the rescuer relative to the victim, the position of the rescuer’s hands, and the rate and force of compression. The victim must be supine, the head level with the heart, for adequate brain perfusion. Compressions are performed most effectively if the rescuer’s hips are on the same level, or slightly above the level of, the victim’s chest. Standard technique consists of the rhythmic application of pressure over the lower half of the sternum. The heel of one hand is placed on the lower sternum, and the other hand is placed on top of the first one. Great care must be taken to avoid pressing the xiphoid into the abdomen, which can lacerate the liver. Applying pressure on the ribs by improper hand placement increases these complications and risks puncturing the lung. Pressure on the sternum should be applied through the heel of the hand only, keeping the fingers free of the chest wall. The direction of force must be straight down on the sternum, with the arms straight and the elbows locked into position so the entire weight of the upper body is used to apply force. Inadequate chest recoil due to leaning on the chest during the relaxation phase has been demonstrated to be both common and deleterious to effective chest compressions. During relaxation, care must be taken to remove all pressure from the chest wall, but the hands should not lose contact with the chest wall. The sternum must be depressed at least 2 to 2½ in (5 to 6 cm) in adults and teens. The duration of compression should be equal to that of relaxation, and the compression rate should be 100 to 120 times per minute. With an 4176 advanced airway in place, ventilations at a rate of 1 breath every 6 seconds should be interposed between compressions without a pause. If return of spontaneous circulation has not been achieved in that time, the outcome is dismal. Unfortunately, none of the alternatives has proved reliably superior to the standard technique.
Its predictable and rapid elimination is unaffected by hepatic or renal disease discount cymbalta online mastercard, making it an optimal drug for infusion techniques cheap 20 mg cymbalta visa. Abdominal and chest wall rigidity commonly occur with rapid injection of high doses of opioids and can be severe enough to render ventilation impossible cymbalta 20mg lowest price. A low dose (priming) of nondepolarizing muscle relaxant should be given prior to a high-dose opioid administration purchase cymbalta 40 mg without prescription. Induction Drugs Benzodiazepines, barbiturates, propofol, and etomidate can be used as supplements to either inhalation or opioid anesthetics, or as sole induction drugs in patients with cardiac disease depending on the adequacy of ventricular function and baseline sympathetic tone. Etomidate is favored for induction in patients with limited cardiac reserve, but rarely administered repeatedly or for prolonged periods because of the risk of adrenal dysfunction associated with prolonged use. Although they are not essential to surgical exposure of the heart, muscle paralysis facilitates intubation of the trachea and attenuates skeletal muscle contraction during defibrillation. The chief criteria for selection are the hemodynamic and pharmacokinetic properties associated with each relaxant, the patient’s myocardial function, the presence of coexisting disease, current pharmacologic regimen, and anesthetic technique. Anticipation of needs specific to each stage of the procedure and immediate availability of necessary equipment and medications prevent untoward hemodynamic aberrations and last-minute rushed decisions. Table 39-12 provides a checklist to aid in proper preoperative preparation of the operating room. Any angina should be promptly treated with supplemental oxygen, additional sedation, intravenous nitroglycerin, or, if related to anxiety-induced hypertension or tachycardia, with β-blocker and prompt induction of general anesthesia if possible. Peripheral intravenous cannulae are inserted after site infiltration with local anesthetic (additional routes for infusion are desirable in patients 2723 undergoing repeat cardiac surgery). Although some anesthesiologists induce anesthesia and insert arterial and central venous cannulas following tracheal intubation, others prefer to have one or both of these cannulae inserted prior to induction of anesthesia. Surface ultrasound for central venous access should be the standard practice, and at all times sterile barrier technique should be adhered to. Throughout the preinduction period, the anesthesiologist must never divert his or her attention from the patient. Induction and Intubation The exact choice and sequence of drugs are a subtle—sometimes not so subtle —combination of art and science. A smooth transition from consciousness to blissful sleep is desired without untoward airway difficulties (e. A “slow cardiac induction” sometimes causes, rather than alleviates, these potential problems. However, awake tracheal intubation, after proper sedation, may be appropriate in an obese patient with a wide neck if ventilation and intubation appear to be difficult. Deep planes of anesthesia, brief duration of laryngoscopy, and innumerable pharmacologic regimens have been proposed for eliminating the hypertension and tachycardia associated with intubation of the trachea. None is uniformly successful, and all drug interventions carry some degree of risk, even though they may be small. In patients with a slow heart rate prior to induction of anesthesia, the reflex response to tracheal intubation is primarily vagal, and severe bradycardia and rarely sinus arrest can occur. Identification of persistently abnormal hemodynamics or ischemia should be sought and treated. It may be necessary to reduce the anesthetic depth or alternatively support the systemic pressure with a vasoconstrictor. The potential risks of vasoconstriction in patients with poor left or right ventricular performance must be kept in mind. The anesthetic depth should be increased immediately prior to incision and sternotomy. Incision to Bypass As previously emphasized, the prebypass period is characterized by periods of intense surgical stimulation that may cause hypertension and tachycardia, or induce ischemia. Anticipating these events and deepening the anesthetic may be effective, but a vasodilator or other adjuvant is often required. This may interfere with venous return or produce episodic ectopic beats or sustained supraventricular dysrhythmias, and atrial fibrillation is not uncommon. Depending on the blood pressure and heart rate response, appropriate treatment may range from observation to vasoconstrictors, cardioversion, or rapid cannulation and institution of bypass. Maintaining adequate intravascular volume may attenuate the extent of hypotension. This is a critical period, and continuous observation of the surgical field is essential. Communication between the anesthesiologist and the surgeon is necessary to keep both apprised of the situation and to ensure the heart gets a periodic “rest during periods of manipulation. Once adequate mixing is obtained, blood pressure increases to levels determined primarily by flow rate, and secondarily by total vascular resistance (Table 39-14). There is no consensus as to what constitutes the ideal blood pressure or flow rate for adequate vital organ perfusion, especially of the brain, during bypass. Of primary importance is continuous observation of the surgical field and cannulae to exclude mechanical obstruction to flow. Attention can then be directed to other causes of hypotension or hypertension and their treatment. Anesthetic requirements are decreased during the period of hypothermia but return toward normal when the patient is rewarmed. Table 39-13 Checklist before Initiating Cardiopulmonary Bypass Arterial pH and mixed venous oxygen saturation, often measured online, 2726 are used to assess the adequacy of perfusion. Although many institutions administer diuretics routinely, they are just as assiduously avoided elsewhere. Table 39-14 Checklist during Cardiopulmonary Bypass Rewarming When surgical repair is nearly complete, gradual rewarming of the patient begins. A gradient of 4° to 6°C is maintained between the patient and the perfusate to prevent formation of gas bubbles, and blood temperature should be less than 37°C. If adequate doses of anesthetics have not been given, administration during rewarming should be considered to prevent recall of intraoperative events. On completion of the surgical repair any residual intracardiac air is removed as the anesthesiologist is vigorously ventilating the lungs to remove air from the pulmonary veins and aid in filling the cardiac chambers. If necessary, heart rate and rhythm are regulated either pharmacologically or electrically (appropriate pacing, defibrillation, cardioversion), and vasoactive infusions started. The venous cannula(e) are then occluded incrementally and sufficient pump volume is transfused into the patient, while the bypass flow is slowly decreased (Fig. The potential disparity between radial artery and aortic pressures must be kept in mind. Inadequate cardiac performance must prompt a search for possible causes (Table 39-16); structural defects require more than mere regulation of inotropes or vasodilators. An approach to patients with inadequate cardiac output is summarized in Table 39-17. It is important not to overdistend the heart by transfusing to an arbitrary level of filling pressure because this may result in further myocardial dysfunction. The ratio of systemic to pulmonary artery pressure is also helpful131; if increasing, the pulmonary artery pressure should increase at the same degree/rate as the systemic pressure (Fig. If pharmacologic support is required, an integration of cardiac physiology (see Chapter 12) and pharmacology will lead to an appropriate selection. Numerous algorithms are available to guide decision making; one is presented in Figure 39-12. This algorithm uses systemic arterial and pulmonary artery pressures and cardiac output. After integrating available data, a diagnosis is made and appropriate treatment is begun. Continual reassessment of the situation is necessary to document the efficacy of treatment or to suggest new diagnoses and therapeutic approaches. If these initial therapies are insufficient to promote adequate forward flow, various combinations of drugs may be tested. Table 39-16 Etiology of Right or Left Ventricular Dysfunction after Cardiopulmonary Bypass A therapeutic approach to right ventricular failure (Fig. When pulmonary arterial pressure is normal or decreased, the cause is usually severe right ventricular ischemia secondary to intraoperative events or air. Combination therapy with differential infusions refers to infusion of inotropes with vasoconstrictive properties into the left side of the circulation to maintain systemic perfusion, while avoiding an increase of the pulmonary circulation resistance. Table 39-18 Medications Given by Continuous Infusion Intra-aortic Balloon Pump The simplest and most readily available mechanical support device is the 2733 intra-aortic balloon pump. It is usually inserted into the femoral artery, either percutaneously or after surgical exposure, and advanced so the distal tip is below the left subclavian artery (to prevent emboli to the head vessels) and the proximal above the renal arteries. It uses synchronized counterpulsation to assist a beating, ejecting heart: blood volume is moved in a direction “counter” to normal flow.