What peripheral nerve block can be performed for surgery of the lower extremity

The first step in deciding what block is indicated for anesthesia or analgesia is appreciating the innervation of the lower extremity and the requirements of the proposed procedure. The lumbar plexus (L1-L4) gives origin to the ilioinguinal, genitofemoral, obturator, femoral, and lateral femorocutaneous nerves and mainly innervates the inguinal region and the anterior aspect of the thigh. The rest of the lower extremity is innervated by the sacral plexus. This includes the posterior aspect of...

Describe the pulmonary artery waveform

Perhaps the most noticeable change as the catheter tip enters the PA is the upstroke in diastolic pressure (Figure 26-2). Other features include a rapid upstroke, a progressive diastolic runoff, and a dicrotic notch secondary to pulmonic valve closure (Figure 26-3). Peak systole is found after the QRS complex but before the peak of the T wave. End diastole is found near the end of the QRS complex. Figure 26-2. Diastolic pressure increases as the pulmonary artery (PA) catheter tip crosses from...

What is diastolic dysfunction

Diastolic dysfunction can occur with normal LV EF in many patients. Impaired LV relaxation or compliance or both are the major characteristic features of LV diastolic dysfunction. Early diastolic filling depends on the rapidity of ventricular relaxation, characterized by an Figure 34-1. Left ventricular (LV) pressure-volume loops illustrating normal performance (loop 1), diastolic (loop 2), and systolic dysfunction (loop 3). AB, Diastolic filling BC, isovolumic contraction CD, ejection DA,...

Degenerative neurologic diseases and neuropathies

What is amyotrophic lateral sclerosis and its anesthetic considerations Also known as Lou Gehrig's disease, amyotrophic lateral sclerosis (ALS) is a disease of both upper and lower motor neurons. It usually affects men in the fourth or fifth decade of life. Patients with ALS develop progressive weakness and eventually die (from pneumonia and pulmonary failure), often in a 3- to 5-year period. Although extremities are involved first, eventually bulbar muscles become affected, increasing the risk...

Describe the functionally distinct compartments of body water using a 70kg patient for illustration

Accurate estimations are difficult because ordinarily ideal body weight (IBW) is used as a basis for calculation. Obesity is rampant in our society, making accurate estimations difficult. Figure 4-1 estimates body water compartments in a patient with an IBW of 70 kg. Compartment percent of total body weight Figure 4-1. Body water compartments in a patient with an ideal body weight of 70 kg. BV, Blood volume ECF, extracellular fluid ICF, intracellular fluid ISF, interstitial fluid.

How often does the preoperative evaluation alter care plans

It has been found that care plans were altered in 20 of all patients (including 15 of American Society of Anesthesiologists ASA class 1 and 2 patients) because of conditions identified at the preoperative evaluation. The most common conditions resulting in changes were gastric reflux, insulin-dependent diabetes mellitus, asthma, and suspected difficult airway. These findings indicate that, whenever possible, it is preferable in all patients to do the preoperative evaluation before the day of...

How does prone ventilation improve oxygenation

The primary pulmonary defect based on computed tomographic scans of supine patients with ARDS is the opacification of the gravity-dependent areas of the lung as a result of atelectasis and consolidation. Clearly alveolar flooding from formation of edema fluid is partially responsible for the atelectasis, but mechanical imbalances caused by cephalic displacement of Sustained inflation CPAP a CPAP of 30-40 cm H2O High-frequency ventilation High-frequency oscillation Use reverse Trendelenburg...

Key Points Perioperative Hepatic Dysfunction

Patients with end-stage liver disease have a hyperdynamic circulation with increased cardiac output and decreased systemic vascular resistance. 2. Although the portal vein supplies up to 75 of total hepatic blood flow, only 45 to 55 of the oxygen requirements are provided by this part of the circulation. 3. Because of the large reserve of the liver, significant impairment of physiologic function must occur before clinical signs and symptoms of hepatic failure become evident. 4. Because of...

Of Elevated

Hypotonic or glucose-containing intravascular fluid 4. High concentrations of inhalation agents 20. What are the mechanisms behind traumatic brain injury The damage to the brain after traumatic injury can be divided into two categories 1. Damage from the primary mechanism of injury 2. Damage from secondary insults (hypotension, hypoxia) The primary mechanism (e.g., motor vehicle crash, gunshot) can result in focal or global damage to the brain tissue. Focal injuries are primarily caused by...

Other Motor Diseases

MH is a hypermetabolic disorder that presents in the perioperative period after exposure to inhalational agents or succinylcholine. 2. Early recognition is critical and treatment is complex and multifaceted, requiring the assistance of other experienced personnel. 3. The sine qua non of MH is an unexplained rise in end-tidal carbon dioxide in a patient with unexplained tachycardia. A temperature rise is a late feature. 4. Patients with a history of MH or who are MH susceptible must receive...

Outline the hemodynamic goals of induction and maintenance of general anesthesia in patients with IHD

The anesthesiologist's goal must be to maintain the balance between myocardial oxygen demand and supply throughout the perioperative period. During induction wide swings in heart rate and blood pressure should be avoided. Ketamine should be avoided because of the resultant tachycardia and hypertension. Prolonged laryngoscopy should be avoided, and the anesthesiologist may wish to blunt the stimulation of laryngoscopy and intubation by the addition of opiates, p-blockers, or laryngotracheal or...

Relate the advantages and disadvantages of spinal anesthesia for cesarean section Which drugs are frequently used in

Spinal anesthesia produces a dense neural blockade it is relatively easy to perform, has a rapid onset, and carries no risk of local anesthetic toxicity. The development of small-gauge, noncutting needles has significantly reduced the incidence of postdural-puncture headache (PDPH) to 1 or less. Hypotension can be treated by rapid hydration (1 L colloid or 1 to 2 L crystalloid), positioning to avoid aortocaval compression, and use of phenylephrine (50 to 100 mcg) or ephedrine (5 to 10 mg IV) if...

Relative contraindications

Advanced chronic renal failure Age > 60 years Portal vein thrombosis Cholangiocarcinoma Hypoxemia with intrapulmonary right-to-left shunts Hepatitis HBsAg and HBeAg positivity HIV positivity without clinical AIDS Modified from Maddrey WC, Van Thiel DH Liver transplantation an overview, Hepatology 8 948,1988. AIDS, Acquired immunodeficiency syndrome HIV, human immunodeficiency virus. syndrome), hepatic disease may be overshadowed by the severity of the comorbid conditions. Prior abdominal...

Renal function and anesthesia

The kidneys are paired organs lying retroperitoneally against the posterior abdominal wall. Although their combined weight is only 300 g (about 0.5 of total body weight), they receive 20 to 25 of the total cardiac output. The renal arteries are branches of the aorta, originating below the superior mesenteric artery. The renal veins drain into the inferior vena cava. Nerve supply is abundant sympathetic constrictor fibers are distributed via celiac and renal...

Review hypokalemia and its causes

A serum level of less than 3.5 mEq L defines hypokalemia. Hypokalemia may be the result of total body loss of potassium (gastrointestinal and renal), transcellular shifts in potassium, or inadequate intake. Diuretics frequently cause hypokalemia, as do gastrointestinal losses and renal tubular acidosis. p-Adrenergic agonists, insulin, and alkalosis (respiratory and metabolic) shift potassium to the intracellular space. Hypokalemia is not uncommon in pregnant women receiving tocolytic therapy or...

Review restrictive lung disorders and their associated pulmonary function test abnormalities

Disorders that result in decreased lung volumes include abnormal chest cage configuration, respiratory muscle weakness, loss of alveolar air space (e.g., pulmonary fibrosis, pneumonia), and encroachment of the lung space by disorders of the pleural cavity (e.g., effusion, tumor). The characteristic restrictive pattern is a reduction in lung volumes, particularly TLC and VC. Airflow rates can be normal or increased. ALTERATIONS IN MEASURES OF LUNG FUNCTION IN OBSTRUCTIVE Adapted from Taylor AE...

Review shivering and nonshivering thermogenesis

Shivering is the spontaneous, asynchronous, random contraction of skeletal muscles in an effort to increase the basal metabolic rate. Shivering is modulated through the hypothalamus and can increase the body's production of heat by up to 300 in young, muscular individuals. It increases oxygen consumption and carbon dioxide production. This effect may be undesirable in the patient with coronary artery disease or pulmonary insufficiency. Infants younger than 3 months of age cannot shiver and...

Review the alleged benefits and risks of garlic

Garlic decreases blood pressure and reduces plasma lipids. It may produce smooth muscle relaxation and vasodilation by activation of endothelium-derived relaxation factor. It has been shown to have antithrombotic properties by increasing thrombolytic activity secondary to plasminogen activation and decreasing platelet aggregation through inhibition of thromboxane B2 formation. Garlic may potentiate the effects of warfarin, heparin, nonsteroidal antiinflammatory drugs (NSAIDs), and aspirin. A...

Review the effects of St Johns wort

John's wort is used for the treatment of mild to moderate depression through impaired reuptake of serotonin, norepinephrine, and dopamine. As such, when taken in conjunction with selective serotonin reuptake inhibitors (SSRIs) prescribed by a physician, serotonin excess may be an undesired effect. Like SSRIs, St. John's wort should also not be administered to patients on monoamine oxidase inhibitors and p-sympathomimetic amines such as pseudoephedrine). It may alter the metabolism of...

Should neuromuscular blockade be used to facilitate mechanical ventilation

Neuromuscular blocking agents (NMBAs) are commonly used to facilitate MV during ARDS but, despite wide acceptance, there are few data and as yet no consensus available for when these agents should be used. Gainnier and associates (2004) were the first to report the effects of a 48-hour NMBA infusion on gas exchange in patients with early ARDS. All patients were ventilated according to the ARDSNet protocol. Significant improvements in oxygenation and ability to lower PEEP occurred in the NMBA...

Should parents be allowed to accompany their children to the operating room

Young children may become anxious and frightened when they are separated from their parents. Allowing parents to accompany children to the operating room (OR) may facilitate anesthetic induction in some cases. Parents and children should be educated and prepared for what to expect, and parents should be prepared to leave when the anesthesiologist believes it to be appropriate. Anxious, reluctant, or hysterical parents are a hindrance. An anesthesiologist who is not comfortable with parental...

Summarize the usual presentation major risk factors and management ol pulmonary artery rupture

Pulmonary artery rupture usually manifests as rapid hypotension with hemoptysis. Major risk factors for pulmonary artery rupture include pulmonary hypertension cardiopulmonary bypass hypothermia and aggressive or excessively prolonged balloon inflation, tip migration, and catheter manipulation. Management includes fluid resuscitation, leaving the PA catheter in place, placing a double-lumen endotracheal tube to isolate the affected lung, reversing anticoagulation if any, and preparing the...

Under what circumstances is a patient slow to awaken

A reasonable initial assumption is that such patients are displaying residual drug effects. Should decreased awareness persist beyond a reasonable period of observation, ventilatory, metabolic, and central nervous system (CNS) etiologies must be considered. Does the patient have a seizure history and is the patient currently postictal CNS ischemia caused by decreased perfusion or embolic phenomena should be considered. Has the patient had documented CNS ischemic events or strokes Laboratory...

What agents can be used for induction and maintenance of general anesthesia

The standard induction agents can all be used safely. Ketamine produces bronchodilation secondary to its sympathomimetic effects by direct antagonism of bronchoconstricting mediators, but secretions increase remarkably. Anecdotal evidence exists of bronchodilating properties from propofol. Intravenous lidocaine given before intubation can help blunt airway reflexes. All volatile anesthetics produce bronchodilation. Desflurane is an airway irritant, although once the patient is intubated this is...

What are predictors of difficult mask ventilation Why is this important

There is much focus on intubation and predictors of difficult intubation. It should be recognized that the ability to mask-ventilate a patient is equally and perhaps more important. For instance, if it is determined at the time of intubation that perhaps a patient is impossible to intubate by conventional laryngoscopy, if the patient's oxygen saturations can be maintained through mask ventilation, the situation remains under a degree of control while help and additional airway management tools...

What are some anesthetic concerns that arise during stage 2 the anhepatic phase

Once the dissection is finished, blood loss is usually minimal, but blood volume may be decreased from hemorrhage during the preanhepatic phase. Because the inferior vena cava is typically cross-clamped, half of the patient's blood volume is confined to the lower body. Therefore central filling pressures are a poor representation of total body blood volume. Most therapy in this phase is directed toward achieving hemodynamic stability and preparing for reperfusion by correcting potassium and pH....

What are some of the adverse effects of electroconvulsive therapy

An induced seizure lasting longer than 2 or 3 minutes is considered prolonged and can result in increased cognitive deficits. Prolonged apnea is said to occur if it takes longer than 5 minutes to regain spontaneous ventilations after ECT treatment and may be caused by a pseudocholinesterase deficiency, resulting in prolonged succinylcholine activity. Emergence delirium is characterized by restless agitation, aimless repetitive movements, grasping objects in view, or restless attempts to remove...

What are the advantages and disadvantages of cesarean section with epidural anesthesia vs spinal anesthesia What are

If epidural analgesia is used for pain relief during labor and delivery, higher concentrations of local anesthetics can provide surgical anesthesia. The local anesthetic should be given in increments, titrating to the desired sensory level. Titration of local anesthetic results in more controlled sympathetic blockade thus the risk of hypotension and reduced uteroplacental flow may be decreased. Typically epidural anesthesia produces less intense motor and sensory blockade than spinal...

What are the anesthetic considerations in patients with preeclampsia

Before initiation of neuraxial anesthesia, evaluation of coagulation status is recommended. Because thrombocytopenia is the most common coagulopathy in preeclampsia, a screening platelet count is recommended. Although an arbitrary platelet count of 100,000 is often suggested, the actual platelet count safe for spinal or epidural placement is unknown. Spinal anesthesia has been controversial in patients with severe preeclampsia because of the potential risk of sudden hypotension with rapid onset...

What are the characteristics of a left bundlebranch block

In V1 there is a broad, deep S wave (or QS wave), with ST segment elevation, that may be preceded by a very narrow R wave (Figure 22-2). In lead I there is a broad R wave (sometimes notched) without a Q or S wave. Figure 22-2. Typical appearance of a left bundle-branch block in V1. In some cases a narrow R wave precedes the large monomorphic S wave. Figure 22-2. Typical appearance of a left bundle-branch block in V1. In some cases a narrow R wave precedes the large monomorphic S wave. The left...

What are the clinical risk factors for a major perioperative cardiac event

The Revised Cardiac Risk Index (Table 17-4) has six components history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, surgical risk, and elevated preoperative serum creatinine. The patient is assigned one point for each of these risk factors, which are then translated into percentage risks of perioperative major cardiac events such as myocardial infarction, pulmonary edema, ventricular fibrillation,...

What are the features of informed consent

Informed consent involves the communication of the anesthetic plan in terms the patient understands and covers everything from premedication and preoperative procedures to intraoperative management and postprocedural care (e.g., management of pain, nausea, and vomiting). The alternatives, potential complications, and risks vs. benefits are discussed, and the patient's questions are answered. Preoperative evaluation and informed consent establish a trusting doctor-patient relationship that...

What are the hemodynamic goals in the anesthetic management of patients with aortic insufficiency

In acute AI the goal is to achieve the lowest tolerable systemic blood pressure to increase the stroke volume and CO. Appropriate preload is necessary for maintenance of forward flow. Modest tachycardia reduces ventricular volumes and limits the time available for regurgitation. Contractility must be maintained p-adrenergic agonists may be used if necessary. Dobutamine can be ideal because it does not increase the afterload. Afterload reduction augments forward flow, but additional...

What are the indications and contraindications for epidural analgesia during labor and delivery

Relief of labor-induced pain is sufficient reason for placing an epidural catheter. Analgesia can be readily converted to anesthesia by increasing the local anesthetic concentration, thus facilitating forceps or cesarean delivery. Labor analgesia benefits patients with hypertension and some types of cardiac disease (e.g., mitral stenosis) because it blunts the hemodynamic effects that accompany uterine contractions (increased preload, tachycardia, increased systemic vascular resistance,...

What are the indications for using succinylcholine

SCH provides the most rapid onset and termination of effect of any neuromuscular blocker (NMB) currently available. Its onset is 60 to 90 seconds, and the duration of effect is only 5 to 10 minutes. When the patient has a full stomach and is at risk for pulmonary aspiration of gastric contents, rapid paralysis and airway control are priorities, and SCH is often the drug indicated. (Rocuronium when given in large doses also has a SCH-like onset of action, although a prolonged duration of effect...

What are the initial ventilator settings in acute respiratory failure

Commonly one begins with theVC-A-C mode, which ensures delivery of a preset VT. Pressure-cycled modes are acceptable but probably offer only theoretic advantage. The FiO2 begins at 1 and is titrated downward as tolerated. High FiO2 in the face of acute lung injury results in worsening of intrapulmonary shunting, probably as a result of absorption atelectasis. VT is based on ideal body weight (IBW) and the pathophysiology of lung injury. Volumes of 6 to 10 ml kg IBWare acceptable as long as the...

What are the major causes and presentations of spontaneous subarachnoid hemorrhage

Intracranial aneurysm rupture is the most common cause of subarachnoid hemorrhage (SAH) (75 to 80 ). Risk factors are smoking and systemic hypertension. Rupture depends on the size, with a 6 chance per year if the aneurysm is 25 mm or larger. Arteriovenous malformation (AVM, 5 ), idiopathic ( 14 ), hemorrhagic tumors, and vasculitides are other causes. SAH often presents as a severe frontal or occipital headache, often with associated neurologic deficits, photophobia, stiff neck, and nausea...

What are the most commonly used parenteral opioids for labor analgesia Which side effects are of special concern to the

Table 60-1 summarizes commonly used parenteral opioids and their side effects. In general, intravenous medications help the parturient tolerate labor pain but do not provide complete analgesia. The incidence of side effects and efficacy of analgesia are dose dependent. Maternal sedation and nausea are common. Opioids easily cross the placenta and may cause a decrease in fetal heart rate variability. In addition, intravenous opioids may cause neonatal respiratory depression and neurobehavioral...

What are the most important physiologic changes during labor

During active labor cardiac output increases by 40 above prelabor values. Immediately after delivery cardiac output sharply increases, reaching 75 of prelabor values. This is mainly caused by autotransfusion during uterine contractions, particularly after delivery of the placenta. Hyperventilation is common during active labor and may contribute to the preexisting respiratory alkalosis leading to uterine vasoconstriction and decreased placental perfusion, hypoxemia, and fetal distress. Regional...

What are the ramifications of awareness

Intraoperative awareness has a powerful association with patient dissatisfaction. Untreated pain is one such disturbing possibility. Other possibilities include the ability to hear operating personnel, sensations of weakness or paralysis, anxiety, helplessness, and fear of death. Subsequent effects can range from sleep disturbances, anxiety, and depression to posttraumatic stress disorder (PTSD). One study indicated late psychological symptoms occurred in 33 of patients with awareness. Symptoms...

What are the risks involved in consuming ephedra

Ephedra alkaloids have been marketed as a way to boost energy and lose weight. These compounds are powerful cardiovascular and central nervous system stimulants, and severe hypertension, dysrhythmias, myocardial infarction, acute psychosis, seizures, cerebrovascular accidents, and death have been associated with their use. It may be particularly toxic when combined with caffeine. Many hundreds of people have been hospitalized after their use and, as mentioned previously, the FDA has prevented...

What blood pressure value is considered hypertensive

Blood pressure (BP) changes throughout the day and can be affected by posture, exercise, medications, smoking, caffeine ingestion, and mood. HTN cannot be diagnosed on the basis of one abnormal BP reading but requires sustained elevations over multiple measurements on different days. Systemic hypertension is usually considered sustained elevations of diastolic BP greater than 90 to 95 mm Hg or a systolic BP greater than 140 to 160 mm Hg. Borderline HTN is...

What endotracheal tubes are available

Endotracheal tubes come in a multitude of sizes and shapes. They are commonly manufactured from polyvinyl chloride, with a radiopaque line from top to bottom standard-size connectors for anesthesia circuits or resuscitation bags a high-volume, low-pressure cuff and pilot balloon and a hole in the beveled, distal end (the Murphy eye). Internal diameter Figure 8-2. Schematic diagram demonstrating the head position for endotracheal intubation. A, Successful direct laryngoscopy for exposure of the...

What historical information might be useful in assessing a patients airway

Patients should be questioned about adverse events related to previous airway management episodes. For instance, have they ever been informed by an anesthesiologist thatthey had an airway management problem (e.g., difficult to ventilate, difficult to intubate) Have they had a tracheostomy or other surgery or radiation about the face and neck Have they sustained significant burns to these areas Do they have obstructive sleep apnea, snoring, or temporomandibular joint (TMJ) dysfunction Review of...

What is a pheochromocytoma and what are its associated symptoms How is pheochromocytoma diagnosed

Pheochromocytoma is a catecholamine-secreting tumor of chromaffin tissue, producing either norepinephrine or epinephrine. Most are intra-adrenal, but some are extra-adrenal (within the bladder wall is common), and about 10 are malignant. Signs and symptoms include paroxysms of hypertension, syncope, headache, palpitations, flushing, and sweating. Pheochromocytoma is confirmed by detecting elevated levels of plasma and urinary catecholamines and their metabolites, including vanillylmandelic...

What is closing capacity What factors affect the closing capacity What is the relationship between closing capacity and

Closing capacity is the point during expiration when small airways begin to close. In young individuals with average body mass index, closing capacity is approximately half the FRC when upright and approximately two thirds of the FRC when supine. Closing capacity increases with age and is equal to FRC in the supine individual at approximately 44 years and in the upright individual at approximately 66 years. The FRC depends on position the closing capacity is independent of position. Closing...

What is HELLP syndrome

HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count) is a complication of preeclampsia. Patients develop a microangiopathic hemolytic anemia associated with thrombocytopenia and elevated liver enzymes. Ten to twenty percent of these patients will have normal blood pressure, making the diagnosis sometimes difficult. Although HELLP syndrome is not an indication itself for immediate cesarean delivery, delivery is the only definite treatment for preeclampsia. Patients who...

What is meant by psychologic premedication

Most patients are very anxious before surgery. An informative and comforting visit by an anesthesiologist may replace many milligrams of depressant medication and acts as psychologic premedication. During this visit a full description of the planned anesthetic events to anticipate in the perioperative period should be provided to the patient and family members, and all questions the patient or family may have should be answered. However, psychologic preparation cannot accomplish everything and...

What is normal perfusion pressure breakthrough

This phenomenon of cerebral edema is also called autoregulation breakthrough. It is commonly seen following AVM resection or embolization. With large AVMs the high-flow, low-resistance shunt can lead to underperfusion of adjacent brain tissue so the vessels supplying the underperfused region of brain lose the ability to autoregulate. Once the shunt is excised, all of the blood flow is diverted to the previously marginally perfused tissues, and the maximally dilated vessels are unable to...

What is rapidsequence induction Which patients are best managed in this fashion

It is easiest to appreciate the distinctions of rapid-sequence induction (RSI) if an induction under nonrapid-sequence conditions is understood. Ordinarily the patient has fasted for at least 6 to 8 hours and is not at risk for pulmonary aspiration of gastric contents. The patient is preoxygenated, and an anesthetic induction agent is administered. Once it is established that the patient can be mask-ventilated satisfactorily, a muscle relaxant is given. The patient is then mask-ventilated until...

What is retinopathy of prematurity

Retinopathy of prematurity is a disorder that occurs in premature and occasionally full-term infants who have been exposed to high inspired concentrations of oxygen. Proliferation of the retinal vessels, retinal hemorrhage, fibroproliferation, scarring, and retinal detachment may occur, with decreased visual acuity and blindness. Premature and full-term infants should have limited exposure to high concentrations of inspired oxygen. Oxygen saturation should be maintained between 92 and 95 ,...

What is the best way to treat inhalation injury

Oxygen should be provided as necessary to ensure adequate oxygenation. Bronchospasm usually responds to p-agonists. Patients with smoke inhalation can require greater fluid resuscitation than other patients with burns. Pulmonary toilet may be important if there is excessive carbonaceous material in the lungs. Intubation or tracheotomy may be necessary if there is significant upper airway compromise. Patients with heat and smoke injury plus extensive face and...

What is the difference between acute lung injury and acute respiratory distress syndrome

In 1992 the North American-European Consensus Committee (NAECC) on acute respiratory distress syndrome (ARDS) convened with the goal of providing a clearer and more uniform definition of acute lung injury (ALI) ARDS. Two years later ALI was defined as an acute inflammatory condition resulting in increased lung permeability. The clinical presentation of ALI and ARDS in terms of timing, etiologies, chest film appearance, and lack of primary left atrial hypertension is comparable. ALI ARDS is the...

What is the most common perianesthetic neuropathy

The ulnar nerve is the most frequently injured peripheral nerve, although its incidence is still relatively infrequent. There is a distinct predilection for men older than 50 years of age, and it is not uncommon for there to be a few days' delay in presentation. Occasionally the neuropathy is bilateral. Of interest, the American Society of Anesthesiologists' (ASA) Closed Claims Analysis found that 15 of ulnar neuropathies occurred in patients who were sedated and received spinal or epidural...

What is the most common replacement fluid used in children

A BSS such as lactated Ringer's (LR) with glucose (D5LR) or without glucose (LR) is recommended. Hypoglycemia may occur in healthy children undergoing minimally invasive procedures if glucose-containing fluids are not used, but administration of 5 glucose-containing solutions results in hyperglycemia in the majority of children. Perhaps fluid containing 1 or 2.5 glucose is best. Others still use 5 glucose solutions for maintenance but recommend nonglucose-containing BSS for third space or blood...

What is the pathophysiology of mitral stenosis

As the orifice of the MV narrows, the left atrium experiences pressure overload. In contrast to other valvular lesions, the left ventricle shows relative volume underload because of the obstruction of forward blood flow from the atrium. The elevated atrial pressure may be transmitted to the pulmonary circuit and thus lead to pulmonary hypertension and right heart failure. The overdistended atrium is susceptible to fibrillation with resultant loss of atrial systole, leading to reduced...

What is the physiologic response to electroconvulsive therapy

During ECT a generalized seizure is induced, leading to an acute increase in cerebral blood flow and an associated increase in intracranial pressure (ICP). Immediately following the ECT stimulus, there is a marked transient parasympathetic response that may induce sinus bradycardia, other bradyarrhythmias, asystole, premature atrial or ventricular contractions. This is rapidly followed by a more prominent sympathetic response, resulting in an increase in heart rate of 20 or more and increases...

What is the role of venovenous bypass Are there any alternatives

During the anhepatic phase, after vascular clamps are placed on the inferior vena cava, venous return to the heart drops precipitously. To improve blood return, some physicians use a bypass circuit to return venous blood from the lower part of the body back to the thorax. However, some physicians control the decline in blood pressure that occurs during occlusion of the vena cava with vasopressors rather than with venovenous bypass. Another alternative is to place a cross-clamp over part of the...

What patients are at increased risk for complications after electroconvulsive therapy

ECT should be used cautiously if at all when the effects on cerebral blood flow, ICP, heart rate, and blood pressure may prove problematic to the patient because of coexisting disease. Thus patients with cerebral space-occupying lesions or cerebrovascular disease are at increased risk. Similarly patients with unstable cardiac disease, including patients with uncompensated congestive heart failure, severe valvular disease, unstable angina, recent myocardial infarction, and uncontrolled...

What physiologic effects are related to change in body position

An important consideration is the gravitational effects on the cardiovascular and respiratory systems. A change from an erect to a supine position increases cardiac output secondary to improved venous return to the heart, but there is minimal change in blood pressure secondary to reflex decreases in heart rate and contractility. Conditions that increase intra-abdominal pressure in the supine position, including abdominal tumors, ascites, obesity, pregnancy, or carbon dioxide insufflation for...

What processes can change the usual configuration of the waveform

Asthma and chronic obstructive pulmonary diseases cause a delayed upslope and steep alveolar plateau (Figure 24-6). A commonly seen abnormal capnogram results when the patient makes spontaneous respiratory efforts and inhales before the next mechanical inspiration. This characteristic cleft in the alveolar plateau is a useful clinical sign indicating that the patient has started to breathe (Figure 24-7). Finally, a cuff leak may result in variable early decreases in the normal waveform...

When should a child be premedicated Which drugs are commonly used

Children may have fear and anxiety when they are separated from their parents and during anesthetic induction. Children who are 2 to 6 years old who have had previous surgery or no preoperative tour and education or who fail to interact positively with health care providers in the preoperative area should be premedicated. Children who are anxious during induction may suffer from negative postoperative behavioral changes. Children who receive premedication with midazolam have fewer negative...

When treating acute pain in a chronic pain patient how should the approach differ

When a chronic pain patient has suffered an injury or undergone surgery, the general rule is that the typical dose of oral opioids should be tripled for the first 1 to 2 days. In the preoperative preparation for a chronic pain patient, a one-time dose of gabapentin (900 to 1200 mg) or pregabalin (75 to 100 mg) coupled with a one-time dose of celecoxib (Celebrex) (200 mg) has been shown to improve pain control. After surgery gabapentin or pregabalin can be continued as a regular oral dose, and...

Is it always appropriate to treat sinus tachycardia with bblockers

Sinus tachycardia may be a response to many insults, and the best approach is to identify why the patient is tachycardic and treat the underlying cause. In some cases such as myocardial ischemia from hypertension, p-blockers may be a useful adjunct. In other cases (e.g., acute bronchospasm, pulmonary edema, tamponade, and hypovolemia) p-blockers can be harmful. Pain, fever, volume shifts, and anemia are all important causes of tachycardia to consider in a postoperative patient.

A patient has a right bundlebranch block that is new compared to the ECG from 2 years ago How should I proceed

Although a RBBB can be caused by CAD (e.g., with a large anterior infarct destroying some of the conduction system in the interventricular septum), this is only true in a minority of RBBB patients. Such patients typically have a qR in V1 instead of an rSR' prime because the initial r wave is lost as a consequence of the MI. Occasionally an RBBB may be caused by congenital heart disease (such as tetralogy of Fallot), prior cardiac surgery, a cardiomyopathy, or pulmonary hypertension. History and...

Do all patients with an accessory pathway have a delta wave WPW pattern on their baseline electrocardiogram

Many accessory pathways conduct only in a retrograde fashion (from ventricle to atrium) or have very slow antegrade (atrial to ventricular) conduction. These patients may or may not have narrow-complex SVT (AVRT). In contrast, some patients have a delta wave on the baseline ECG with no clinical symptoms. In many cases these asymptomatic patients do not need pharmacologic treatment or invasive electrophysiologic testing. 26. A 25-year-old patient presenting with palpitations is noted to have...

How can anesthesiologists protect themselves from radiation exposure

Most institutions abide by the ALARA philosophy when it comes to protecting their workers radiation exposure should be kept As Low As Reasonably Achievable. There are three basic strategies to the ALARA philosophy Maximize the distance to the source Newton's inverse square law, which applies to any point source that spreads its influence in all directions (such as light, sound, gravitational field) tells us that the intensity of the radiation at a given radius is the source strength divided by...

Top 100 Secrets

These secrets are 100 of the top board alerts. They summarize the concepts, principles, and most salient details of anesthesiology. 1. Patients should take prescribed p-blockers on the day of surgery and continue them perioperatively. Because the receptors are up-regulated, withdrawal may precipitate hypertension, tachycardia, and myocardial ischemia. Clonidine should also be continued perioperatively because of concerns for rebound hypertension. 2. Under most circumstances peri-induction...

Key Points Concerns In Patients Taking Cocaine

Myocardial ischemia is not uncommon in cocaine-abusing patients, and selective p2-blockade should be avoided because it may cause vasoconstriction and worsen the ischemia. 2. Severe hypertension and tachycardia are risks during airway management unless the patient is deeply anesthetized. 3. Cocaine sensitizes the cardiovascular system to the effects of endogenous catecholamines. Ketamine and pancuronium potentiate the cardiovascular toxicity of cocaine and should be avoided. 26. What is crystal...

What is an acceptable preoperative platelet count

A normal platelet count is 150,000 to 440,000 mm3. Thrombocytopenia is defined as a count of < 150,000 mm3. Intraoperative bleeding can be severe with counts of 40,000-to 70,000 mm3, and spontaneous bleeding usually occurs at counts < 20,000 mm3. The minimal recommended platelet count before surgery is 75,000 mm3. However, qualitative differences in platelet function make it unwise to rely solely on platelet count. Thrombocytopenic patients with accelerated destruction but active production...

Review the pros and cons of induction agents in asthmatic patients

Intravenous induction agents used in asthmatic patients include oxybarbiturates, thiobarbiturates, ketamine, and propofol. Thiobarbiturates constrict airways in laboratory investigations and may have a loose association with clinical bronchospasm. The most common cause of bronchospasm is the stimulus of intubation, and large doses of barbiturates are required to block this effect successfully. Ketamine has well-known bronchodilatory effects secondary to the release of endogenous catecholamines...

What is the significance of portal pulmonary hypertension How are these patients managed in the pretransplant period

In contrast to mosttransplant recipients, portal pulmonary hypertension (PPHTN) patients have an increased risk of death because of right ventricular failure in the peritransplantation period. Physicians are uncertain which PPHTN patients may undergo transplantation because there are no patient characteristics that clearly predict outcome. Patients with moderate to severe PPHTN should not be considered candidates until they undergo a trial of vasodilator therapy. The cause of pulmonary...

Diabetes mellitus

Slover, MD, and Robin Slover, MD 1. Describe the principal types of diabetes mellitus. Type 1 diabetes mellitus An autoimmune disorder in which destruction of the pancreatic islet cells results in the inability to produce insulin. Onset is more common in children and young adults. Type 2 diabetes mellitus A disorder in the body's ability to use insulin. Early in the course of the disease the patient may be able to make sufficient insulin, but cell-receptor impairment results in...

A 3yearold child presents for an elective tonsillectomy His mother reports that for the past 3 days he has had a runny

Viral upper respiratory infection (URI) alters the quality and quantity of airway secretions and increases airway reflexes to mechanical, chemical, or irritant stimulation. Some clinical studies have shown associated intraoperative and postoperative bronchospasm, laryngospasm, and hypoxia. There is evidence that the risk of pulmonary complications may remain high for at least 2 weeks and possibly 6 to 7 weeks after a URI. Infants have a greater risk than older children, and intubation probably...

How long before surgery must a patient quit smoking to realize any health benefits

All patients who smoke should understand that smoking cessation even immediately before surgery has profound, measurable health benefits. Nicotine is a stimulant and has a half-life of only 1 to 2 hours its adverse effects on systolic blood pressure and heart rate can be seen after only 12 hours of smoking cessation. Carbon monoxide (CO), which diminishes oxygen-carrying capacity, has a half-life of only 4 hours. Diminished levels of nicotine and CO were likely behind the outcome of a study...

What are the causes of intraoperative wheezing and the correct responses to asthmatic patients with acute bronchospasm

Causes include airway secretions, foreign body, pulmonary edema (cardiac asthma), obstructed endotracheal tube, endotracheal tube at the carina or down a main-stem bronchus, allergic or anaphylactic response to drugs, and asthma. A number of medications cause wheezing in asthmatic patients, including p-blockers, muscle relaxants, and aspirin. After carefully checking the endotracheal tube and listening for bilateral breath sounds, increase the inspired oxygen to 100 and deepen the anesthetic if...

Alcohol and substance abuse

How is alcohol absorbed and metabolized Alcohol is absorbed across the gastrointestinal mucosa, more so in the small intestine than in the stomach. The volume of distribution (Vd) of alcohol is that of body water. Alcohol easily crosses the blood-brain barrier. Arterial blood levels of alcohol correlate well with concentrations in lung alveoli, thus the basis of the breathalyzer test used by law-enforcement officers. Alcohol is metabolized primarily in the liver. Most consumed alcohol is...

How is hyponatremia classified

Hyponatremia may occur in the presence of hypotonicity, normal tonicity, or hypertonicity thus it is important to measure serum osmolality to determine the cause of hyponatremia. Assessment of volume status is also important in determining the cause. An excess of total body water is more common than a loss of sodium in excess of water. Table 5-1 summarizes causes and treatment of hyponatremia. Congestive heart failure cirrhosis SIADH, Syndrome of inappropriate antidiuretic hormone.

Describe the lithotomy position and its common complications

Common Positions For Anesthesia

The patient's hips and knees are flexed, and the patient's feet are placed in stirrups to gain ready access to the genitalia and perineum. The range of flexion may be modest low lithotomy or extreme high lithotomy . The feet may be suspended on vertical structures known as candy canes or in boots, or the knees may be supported with crutches. With elevation of the legs, pressure is taken off the lower back, and blood is translocated from the lower extremities to the central compartments....

Explain the gate theory of pain

In 1965 Melzack and Wall proposed that the substantia gelatinosa in the spinal cord was the primary gate in the transmission of noxious and nonnoxious stimulus to the central nervous system. The pain gate is opened by information coming from slow unmyelinated C fibers and closed by the impulses from faster myelinated fibers such as A-p. Since pain is transmitted by slow A-S and C fibers, they reason that, by activating faster fibers such as the ones that transmit proprioception, the gate will...