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Friday, April 21, 20231

Anesthesia and pulmonary diseases


Thoracic and upper abdominal operations are a particular risk for patients with chronic pulmonary disease.

Obstructive airway diseases


Asthma and chronic obstructive pulmonary disease (COPD), the two major categories of obstructive airway disease, affect millions of Americans and cause significant morbidity and mortality worldwide.


Asthma is a chronic inflammatory disorder of the airways characterized by variable airflow obstruction, airway inflammation, and bronchial hyperresponsiveness.


In contrast, the airflow obstruction in COPD is defined as progressive and not fully reversible. The chronic inflammation of the airways and lung parenchyma in COPD is most often secondary to cigarette smoke exposure.


Together, asthma and COPD constitute a major public health concern, and a basic understanding of these diseases is important when caring for patients who receive anesthesia.

ASTHMA


Asthma is a disease that is defined by the presence of:

(1) Chronic inflammatory changes in the submucosa of the airways

(2) Airway hyperresponsiveness

(3) Reversible expiratory airflow obstruction.


Airway hyperresponsiveness characterizes this disease, even in asymptomatic patients, and is demonstrated by the development of bronchoconstriction in response to stimuli (allergens, exercise, mechanical airway stimulation) that have little or no effect on normal airways. Airway hyper responsiveness elicited during methacholine bronchoprovocation and airway bronchodilation in response to inhaled albuterol help diagnose asthma.

Clinical Symptoms


The classic symptoms associated with asthma are cough, shortness of breath, and wheezing. However, symptoms of asthma may vary and range from cough with or without sputum production to chest pain or tightness. Chronic,

nonproductive cough may be the sole initial complaint.


Some asthmatics also experience symptoms exclusively

with exertion ("exercise-induced asthma"), and this diagnosis

is a consideration in the pediatric and young adult population.


The presence or absence of wheezing on physical examination is a poor predictor of the severity of airflow obstruction. Thus, the presence of wheezing suggests airway narrowing, which should be confirmed and quantified by spirometry.


Degrees of obstraction are defined according to the FEV1 % predicted .

Reversibility of obstruction after the administration of a

bronchodilator suggests a diagnosis of asthma.


An increase in FEV1 % predicted of more than 12% and an increase in FEVl of greater than 0.2 L suggest acute bronchodilator responsiveness and variability in airflow obstruction.

In contrast, the airways of patients with COPD do not demonstrate reversibility of airflow obstruction to the same degree as do those with asthma, a characteristic that can help distinguish these two causes of airflow obstraction.




During severe asthma exacerbations, intravenous therapy

with glucocorticoids is the mainstay of therapy. In rare

circumstances, when life-threatening status asthmaticuslife-threatening status asthmaticus

persists despite aggressive pharmacologic therapy, it may

be necessary to consider general anesthesia (isoflurane or

sevoflurane) in an attempt to produce bronchodilation.

Management of Anesthesia


Pulmonary function studies (especially FEV1) obtained

before and after bronchodilator therapy may be indicated

in a patient with asthma who is scheduled for a thoracic

or abdominal operation. Measurement of arterial blood

gases before proceeding with elective surgery is a consideration

if there are questions about the adequacy of ventilation or arterial oxygenation.


All asthmatics who have persistent symptoms should be treated with either inhaled or systemic corticosteroids (depending on the severity of their airflow obstruction), in addition to scheduled dose of inhaled beta agonists. Therapy should be continued throughout the perioperative period. Supplementation with cortisol may be indicated before major surgery for corticosteroid-dependent asthmatics because of suppression of the hypothalamic-pituitary-adrenal axishypothalamic-pituitary-adrenal axis.

REGIONAL ANESTHESIA


Regional anesthesia may be preferred when the surgery is

superficial or involves the extremities. Notably, however,

bronchospasm has been reported in asthmatics who have received spinal anesthesia, although it is generally accepted that regional anesthesia is associated with lower complication rates related to bronchospasm in the asthmatic population.

GENERAL ANESTHESIA


The goal during induction and maintenance of general anesthesia in patients with asthma is to depress airway reflexes in order to avoid bronchoconstriction in response to mechanical stimulation of the airway. Before tracheal intubation, a sufficient depth of anesthesia should be

established to minimize bronchoconstriction with subsequent

stimulation of the airway. Rapid intravenous induction of anesthesia is most often accomplished with the administration of propofol or thiopental. Propofol

may blunt tracheal intubation-induced bronchospasm in

patients with asthma.


ketamine (1 to 2 mg/kg IV) is an alternative selection for rapid induction of anesthesia because its sympathomimetic effects on bronchial smooth muscle may decrease airway resistance. The increased secretions associated with the administration of ketamine, however, may limit the use of this drug in patients with asthma.

Sevoflurane and isoflurane are potent volatile anesthetics that depress airway reflexes and do not sensitize the heart to the cardiac effects of the sympathetic nervous system stimulation produced by beta-agonists and aminophylline.


Bronchodilation with sevoflurane and isoflurane depends on the ability of the normal airway epithelium to produce nitric oxide and prostanoids. Halothane is also an effective bronchodilator but may be associated with cardiac dysrhythmias in the presence of sympathetic nervous system stimulation.

Desflurane may be accompanied by increased secretions,

coughing, laryngospasm, and bronchospasm as a result of

in vivo airway irritation.


Although case reports suggest that bronchodilation follows the intravenous administration of lidocaine, the clinical significance of this response is unclear and the data are equivocal.


In asthmatic patients undergoing tracheal intubation, premedication with inhaled albuterol inhaled albuterol should be the first choice of therapy to prevent intubation-induced bronchoconstriction.

Neuromuscular blocking drugs that are not associated with endogenous histamine release may also be used in patients with asthma .


Although histamine release has been attributed to succinylcholine,there is no evidence that this drug is associated with increased airway resistance in patients with asthma.


Intraoperatively, Pao2 and Paco2 can be maintained at

normal levels by mechanical ventilation of the lungs at

a slow breathing rate (6 to 10 breaths/min) to allow

adequate time for exhalation, an important maneuver

in patients with increased airway resistance. This slow

breathing rate can usually be facilitated by the use of a

high inspiratory flow rate to allow the longest possible

time for exhalation. Positive end-expiratory pressure

(PEEP) should be used cautiously because of the inherent,

impaired exhalation in the presence of narrowed airways.


At the conclusion of elective surgery, the trachea may be extubated while the depth of anesthesia is still sufficient to suppress airway reflexes. After the administration of anticholinesterase drugs to reverse the effects of nondepolarizing neuromuscular blocking drugs, bronchospasm may occur but is not usual, which may reflect the protective effects (decreased airway resistance) of simultaneously administered anticholinergics. When extubation is delayed for reasons of safety until the patient is awake (possible presence of gastric contents), intravenous administration of lidocaine may decrease the likelihood of airway stimulation as a result of the endotracheal tube in an awake patient.

Intraoperative Bronchospasm


Airway instmmentation can cause severe reflex bronchoconstriction and bronchospasm, especially in asthmatic patients with hyperactive airways. The bronchospasm that occurs intraoperatively is usually due to factors other than acute exacerbation of asthma. The frequency of perioperative bronchospasm in patients with asthma is low, especially if their asthma is asymptomatic at the time of surgery.


It is important to first consider mechanical causes of obstruction and inadequate levels of anesthesia before initiating treatment of intraoperative bronchospasm.

Fiberoptic bronchoscopy may be useful to rule out mechanical obstraction in the tracheal tube. Asthma related

bronchospasm may respond to deepening of anesthesia with a volatile anesthetic.


If the bronchospasm is due to asthma and persists despite an increase in the concentration of delivered anesthetic drug, albuterol should be administered by attaching a metered-dose inhaler to the anesthetic delivery system. When bronchospasm persists despite B2- agonist therapy, it may be necessary to add intravenous corticosteroids.

CHRONIC OBSTRUCTIVE PULMONARY

DISEASE: EMPHYSEMA AND CHRONIC BRONCHITIS


COPD consists of two entities, emphysema and chronic

bronchitis. The Global Initiative for Chronic Obstructive

Lung Disease (GOLD) guidelines provide criteria

for diagnosis and classification of severity in patients with

symptoms of chronic cough, sputum production, or exposure

to cigarette smoke .



Emphysema is characterized by loss of elastic recoil of the lungs, which results in collapse of the airways during exhalation and increased airway resistance.


Chronic bronchitis is defined by the presence of cough and sputum production for 3 months in each of 2 successive years in a patient with risk factors, most commonly cigarette smoking. It has been estimated that 25% of surgical patients smoke and a further 25% are ex-smokers, thus making COPD an important diagnosis to consider in any patient undergoing anesthesia.

Prediction of Postoperative Outcome


The need for preoperative pulmonary function studies

in patients with COPD is controversial because of the

questionable correlation of these tests with postoperative

outcome. Although the FEV! % predicted has been used

to grade the severity of airflow obstraction, data have

shown that using a multidimensional grading system to

assess the respiratory and systemic extent of COPD is a

better predictor of mortality than using FEV, % alone.

BODE index.


This grading system is based on four variables-

1=Body mass index (B)

2=Severity of airflow obstraction (0)

3=Functional dyspnea (D)

4=Exercise capacity as assessed by the 6-minute walk test (E)



Patients with higher BODE scores were at higher risk for death. Hypercapnia and hypoxemia, as detected by arterial blood gas analysis, may also characterize patients with moderate to severe airflow obstmction. Chronic hypoxemia may lead to

pulmonary hypertension and cor pulmonalepulmonary hypertension and cor pulmonale. Preoperative

detection plus treatment of hypoxemia-induced cor

pulmonale with supplemental oxygen is an important

part of preoperative management.



The presence of COPD does not dictate the use of specific

management of anesthesia. If general anesthesia is selected, a volatile anesthetic with humidified inhaled gases and mechanical ventilation of the lungs is useful. drugs or techniques (regional or general) for the management of anesthesia.


Nitrous oxide may be used, but potential disadvantages include

limitation of the inhaled concentrations of oxygen and passage of nitrous oxide into emphysematous bullae.

Nitrous oxide could lead to enlargement and rupture of these bullae and result in the development of tension pneumothorax.


Opioids are acceptable but are less ideal for maintenance of anesthesia because of the frequent need for high inhaled concentrations of nitrous oxide to ensure amnesia and associated decreases in inhaled concentrations of oxygen. To avoid this problem, administration of a volatile anesthetic at a low concentration may be substituted for nitrous oxide. Postoperative depression of ventilation may also reflect the residual effects of opioids administered intraoperatively.

MANAGEMENTOF VENTILATION


Patients with COPD are ventilated in a manner similar to

those with asthma. Small tidal volumes may be delivered

to decrease the likelihood of gas trapping and barotrauma.

Slow breathing rates are used to permit maximal time for

exhalation. Continued tracheal intubation and mechanical

ventilation of the lungs in the postoperative period are

often necessary after major surgery in patients with severe

emphysema. Postoperative depression of ventilation may

also reflect the residual effects of opioids administered.


Hypercapnia secondary to chronic hypoventilation should not be corrected intraoperatively because it may then be difficult to wean the patient from mechanical ventilation as a result of the decreased respiratory drive in patients who chronically hypoventilate.

Pulmonary HYPERTENSION


Pulmonary hypertension is defined as an elevation in

mean pulmonary artery pressure to levels higher than

25 mm Hg at rest or higher than 30 mm Hg with exercise.

Most cases of pulmonary hypertension are secondary to

cardiac or pulmonary disease; in a minority of cases, the

etiology is unknown and the pulmonary hypertension is

considered primary.

Classification


The World Health Organization has proposed a classification

of pulmonary hypertension that includes pulmonary

hypertension secondary to left heart disease, pulmonary

disease, vascular disease, and primary pulmonary hypertension.

Indicators of disease severity include dyspnea at rest, hypoxemia, syncope, metabolic acidosis indicating

low cardiac output, and signs of right heart failure on

physical examination (elevated jugular venous pressure,

hepatomegaly, and peripheral edema).

Diagnostic Evaluation


Diagnostic evaluation for pulmonary hypertension includes

the electrocardiogram; echocardiogram; chest roentgenogram;

assessment for secondary causes such as pulmonary

embolism (computed tomographic angiography or

ventilation/perfusion scanning), underlying pulmonary

disease (pulmonary function testing), collagen vascular

disease, or liver failure; and right heart catheterization.


Right heart catheterization is the gold standard for diagnosis

because it provides data on the severity of pulmonary

artery hypertension, as well as pulmonary venous pressure

and cardiac output, which have prognostic significance.

In addition, right heart catheterization is a necessary part

of testing for vasodilator response, the first step in the

algorithm to determine appropriate therapy for pulmonary

artery hypertension.

Pathophysiology


Chronic elevation of pulmonary artery pressure leads to

elevated right ventricular systolic pressure, hypertrophy

and dilatation of the right ventricle, and resultant right

ventricular failure. Right ventricular preload and pulmonary

blood flow are dependent on venous return in this setting.



Intraoperative considerations for a patient with severe pulmonary hypertension include maintaining adequate preload, minimizing tachycardia and cardiac dysrhythmias that may decrease cardiac output, and avoiding arterial hypoxemia and hypercapnia, which can increase pulmonary vascular resistance (PVR). Cardiac output from a failing right ventricle is critically dependent on filling pressure from venous return and pulmonary pressure.


Options for treatment of pulmonary hypertension during surgery include inhaled nitric oxide (10 ppm), inhaled prostacyclin (either intermittent or continuous), and phosphodiesterase inhibitors such as milrinone. Pulmonary artery catheters have been used for intraoperative monitoring.

PARTURIENTS


Mortality in pregnant patients undergoing vaginal delivery

is near 50% and may be even higher when cesarean delivery

is performed. Most often, vaginal deliveries are preferred,

although regional anesthesia may be used successfully during

cesarean sections. The danger of decreased venous return

secondary to the sympathetic nervous system blockade

produced by regional anesthesia should be considered.

POSTOPERATIVE PERIOD


In the postoperative period, care must be taken to avoid

large-volume fluid shifts, arterial hypoxemia, systemic

hypotension, and hypovolemia in patients with pulmonary

hypertension. Morbidity and mortality in the postoperative

period are significant concerns, with possible causes

including pulmonary vasospasm, increases in pulmonary

artery pressure, fluid shifts, cardiac dysrhythmias, and

heightened sympathetic nervous system tone.

OBSTRUCTIVE SLEEP APNEA


Patients with obstructive sleep apnea (OSA) are at high risk for postoperative complications when undergoing general anesthesia. OSA is reported to occur in 2% of middle-aged women and 4% of middle-aged men. It is suspected, however, that up to 80% of cases of OSA are undiagnosed, thus suggesting that those with this disorder may be a significant portion of the surgical population.


Obesity is the most significant risk factor for the development

of OSA, with a body mass index greater than 30 and a large neck circumference (>44 cm) being positively correlated with severe OSA. Obese patients with OSA or suspected OSA are at risk for complications during tracheal intubation and extubation, as well as during the postoperative period.,


Comorbid medical illnesses such as hypertension cardiovascular disease, and congestive heart failure are also more prevalent in patients with OSA than in the general population, a fact that contributes to their postoperative morbidity. Systemic hypertension has been reported in up to 50% of patients with OSA and is independent of obesity, age, and gender.


Treatment of OSA by noninvasive ventilation results in better control of systemic hypertension. In addition to systemic hypertension, pulmonary hypertension is more prevalent in these patients than in the general population, One common

mechanism that may explain both the systemic and pulmonary

hypertension in patients with OSA is the chronic decrease

in Pa02 during apneic episodes.



Evaluation of the oral cavity in patients with OSA may not reveal the true nature of their pharyngeal space because increased fat deposition in the lateral pharyngeal walls has been demonstrated in these patients and shown to correlate with the severity of OSA. Neck circumference reflects pharyngeal fat deposition and correlates more strongly with the incidence and severity of OSA than general obesity dose.

IMPACT OF SEDATIVE DRUGS


Relaxation of the upper airway musculature in response to benzodiazepines may significantly reduce the pharyngeal

space and result in longer periods of hypopnea, arterial hypoxemia, and hypercapnia in patients with OSA than in the general population.


Any medications that depress the central nervous system must be administered carefully because airway patency and skeletal muscle tone, maintained in the awake state, may be lost at the

onset of sleep. In addition, opioid analgesics may decrease

the central respiratory drive and thus further add to the

possible complications of sedation.

ANTICIPATION OF DIFFICULT AIRWAY MANAGEMENT


Full preparation for difficult airway management, including

the availability of orotracheal tubes of various size, a

Fastrach laryngeal mask, and a fiberoptic bronchoscope,

should be made before initiating direct laryngoscopy for

tracheal intubation.


Adequate preoxygenation is necessary in obese patients with OSA because of their reduced functional residual capacity and risk for arterial hypoxemia with induction of anesthesia. Tracheal extubation should be performed only when the patient is breathing spontaneously with adequate tidal volumes, oxygenation, and ventilation.

MANAGEMENTIN THE POSTOPERATIVE PERIOD


Respiratory depression and repetitive apnea in the postoperative period can occur in patients with OSA,

especially in the setting of opioid administration for pain

control. It should also be noted that in patients with OSAwho hypoventilate (obesity-hypoventilation syndrome),

careful documentation of preoperative arterial blood gases is necessary to establish the baselinc set point for ventilation, an important factor whcn considering the patient's respiratory drive after extubation.


Relativc hyperventilation intraoperatively to maintain a norma] Paco2 in subjects who chronically hypoventilate may result in prolonged apnea when attempting extubation.

Smoking Cessation


The risk for postoperative pulmonary complications among smokers as opposed to nonsmokers is greatly increased.The length of preoperative smoking cessation necessary to decrease this risk is not clear. It is generally accepted that the increased incidence of postoperative pulmonary complications in smokers can be reduced significantly by persuading the patient to stop smoking before surgery, although there is no consensus on the minimal or optimal duration of preoperative abstinence.

DISCONTINUATION OF SMOKING


Smoking increases airway irritability and secretions, decreases mucociliary transport, and increases the incidence of postoperative pulmonary complications. Cessation of smoking for 12 to 24 hours before surgery decreases the level of carboxyhemoglobin, shifts the oxyhemoglobin

dissociation curve to the right, and increases the oxygen available to tissues.


In contrast to these short-term effects, improvement in mucociliary transport and small airway function and decreases in sputum production require prolonged abstinence (8 to 12 weeks) from smoking. The incidence of postoperative pulmonary complications decreases with abstinence from cigarette smoking for


Nevertheless, it is useful to encourage smoking abstinence in the perioperative

period, especially because smoking shortly before surgery may be associated with an increased incidence of ST-segment depression on the electrocardiogram.


Tuberculosis


Tuberculosis


Mycobacterium tuberculosis is an obligate aerobe responsible for TB. This organism survives most successfully in tissues with high oxygen concentrations, which is consistent with the increased presentation of TB in the apices of the lungs.


Almost all M. tuberculosis infections result from aerosol (droplet) inhalation. It has been estimated that up to 600,000 droplet nuclei are expelled with each cough and remain viable for several days. Although a single infectious unit is capable of causing infection in susceptible individuals, prolonged exposure in closed environments is optimal for transmission of infection.


It is estimated that 90% of patients infected with M. tuberculosis never become symptomatic and are identified only by conversion of the tuberculin skin test. Often patients who acquire the infection early in life do not become symptomatic until much later. Patients who are HIV seropositive or immunocompromised are at much higher risk of becoming symptomatic


Sputum smears and cultures are also used to diagnose TB. Smears are examined for the presence of acid-fast bacilli. This test is based on the ability of mycobacteria to take up and retain neutral red stains after an acid wash. It is estimated that 50% to 80% of individuals with active TB have positive sputum smears. Although the absence of acid-fast bacilli does not rule out TB, a positive sputum culture containing M. tuberculosis provides a definitive diagnosis.


Health care workers are at increased risk of occupational acquisition of TB. For example, TB is twice as prevalent in physicians as in the general population. Persons involved with autopsies are uniquely at risk.

Diagnosis


The diagnosis of TB is based on the presence of clinical symptoms, the epidemiologic likelihood of infection, and the results of diagnostic tests. Symptoms of pulmonary TB often include persistent nonproductive cough, anorexia, weight loss, chest pain, hemoptysis, and night sweats. The most common test for TB is the tuberculin skin (Mantoux) test. The skin reaction is read in 48 to 72 hours, and a positive reading is generally defined as an induration of more than 10 mm.


For patients with AIDS, a reaction of 5 mm or more is considered positive. The skin test is limited, and alternative screening and diagnostic tests are undergoing evaluation. The skin test is nonspecific and may be positive if people have received a bacille Calmette-Guérin vaccine or if they have been exposed to TB, or perhaps even other mycobacteria, even if there are no viable mycobacteria present at the time of the skin test.


Chest radiographs are important for the diagnosis of TB. Apical or subapical infiltrates are highly suggestive of infection. Bilateral upper lobe infiltration with the presence of cavitation is also common. Patients with AIDS may demonstrate a less classic picture on chest radiography, which may be further confounded by the presence of PCP. Tuberculous vertebral osteomyelitis (Pott's disease) is a common manifestation of extrapulmonary TB.


Anesthesiologists are at increased risk of nosocomial TB by virtue of events surrounding the induction and maintenance of anesthesia that may induce coughing (tracheal intubation, tracheal suctioning, mechanical ventilation).Bronchoscopy is a high-risk procedure associated with conversion of the tuberculin skin test in anesthesiologists. As a first step in preventing occupational acquisition of TB, anesthesia personnel should participate in annual tuberculin screening such that those who develop a positive skin test may be offered chemotherapy. The decision to take chemotherapy is not trivial as treatment for TB carries the serious toxicity. A baseline chest radiograph is indicated when a positive tuberculin skin test first manifests



Treatment


Anti-TB chemotherapy has decreased mortality from TB by more than 90%.With adequate treatment, more than 90% of patients who have susceptible strains of TB have bacteriologically negative sputum smears within 3 months. In the United States, vaccination with bacille Calmette-Guérin is not recommended, as it may not confer immunity and confounds the diagnosis of TB.


Some argue that, for protection of the community, people who have positive skin tests should receive chemotherapy with isoniazid. However, the flipside is that isoniazid is a toxic drug and treatment is only strictly indicated if there are radiographic features of pulmonary TB or if there are suggestive symptoms. The toxicity of isoniazid manifests in the peripheral nervous system, liver, and possibly the kidneys. Neurotoxicity may be prevented by daily administration of pyridoxine. Hepatotoxicity is most likely to be related to metabolism of isoniazid by hepatic acetylation. Depending on the genetically determined traits, patients may be characterized as slow or rapid acetylators. Hepatitis appears to be more common in rapid acetylators, consistent with the greater production of hydrazine, a potentially hepatotoxic metabolite of isoniazid. Persistent elevations of serum transaminase concentrations mandate that isoniazid be discontinued, but mild, transient increases do not.


Other drugs used to treat TB include pyrazinamide, rifampicin, and ethambutol. Adverse effects of rifampicin include thrombocytopenia, leukopenia, anemia, and renal failure. Hepatitis associated with increases in serum aminotransaminase concentrations occur in approximately 10% of patients being treated with rifampicin. In order to be curative, treatment for pulmonary TB is recommended for 6 months. Extrapulmonary TB usually requires a longer course. Noncompliance with therapy contributes to the emergence of resistant TB strains.



The preoperative assessment of patients considered to be at risk of TB includes a detailed history, including the presence of a persistent cough and the tuberculin status.Elective surgical procedures should be postponed until patients are no longer considered infectious. Patients are considered noninfectious if they have received antituberculous chemotherapy, are improving clinically, and have had three consecutive negative sputum smears.


If surgery cannot be delayed, it is important to limit the number of involved personnel, and high risk procedures (bronchoscopy, tracheal intubation, and suctioning) should be performed in a negative-pressure environment whenever possible. Patients should be transported to the operating room wearing a tight-fitting N-95 face mask to prevent casual exposure of others to airborne bacilli. Staff should also wear N-95 masks.


If patients have TB of the cervical spine, special precautions should be taken not to injure the spine during airway manipulation. A high efficiency particulate air filter should be placed in the anesthesia delivery circuit between the Y connector and the mask, laryngeal mask airway, or tracheal tube. Bacterial filters should be placed on the exhalation limb of the anesthesia delivery circuit to decrease the discharge of tubercle bacilli into the ambient air. Sterilization of anesthesia equipment (laryngoscope blades) is with standard methods using a disinfectant that destroys tubercle bacilli.


Use of a dedicated anesthesia machine and ventilator is recommended. Positive-pressure ventilation has been associated with massive hemoptysis in a patient with old pulmonary TB leading to the recommendation that maintenance of spontaneous breathing may be indicated in selected patients. Postoperative care should, if possible, take place in an isolation room, preferably with negative pressure.

lists important considerations in regard to tuberculosis.


1. With the acquired immunodeficiency syndrome epidemic, tuberculosis is reemerging worldwide.

2. Multidrug resistant and extensively drug-resistant strains are resistant to therapy and have increased virulence.

3. Symptoms include persistent cough, anorexia, weight loss, chest pain, hemoptysis, and night sweats.

4. Anesthesiologists are at increased risk of nosocomial tuberculosis.

5. Treatment for pulmonary tuberculosis is recommended for 6 months.


6. Noncompliance with therapy contributes to the emergence of resistant tuberculosis strains.

7. Staff and patients should wear N-95 masks.

8. A dedicated anesthesia machine and ventilator should ideally be used.

9. Postoperative care should take place in an isolation room with negative pressure.

UPPER RESPIRATORY TRACT INFECTIONS


Patients may arrive at the hospital for elective tonsillectomy and adenoidectomy with an acute upper respiratory tract infection. Surgery for these patients is usually postponed until resolution of the upper respiratory tract infection, which is typically 7 to 14 7 to 14 daysdays. LaryngospasmLaryngospasm with airway manipulation may be more likely to occur in the presence of an upper respiratory tract infection.


URI has diffuse effects on the respiratory epithelium, mucociliary function, and airway reactivity. These effects combine to provide the potential for an increased risk for anesthesia in specific clinical settings. If the planned surgical

procedure is short and airway support is restricted to the use of a facemask, the risk for an adverse respiratory event is minimal.


If an endotracheal tube is required, the risk for an adverse respiratory event is increased (up to 10- fold) over that in an infant without a URI whose trachea

is not intubated. An LMA seems to be associated with risks midway between those associated with a facemask and those with an endotracheal tube. Younger age plus a ORI seems to be associated with an increased risk from anesthesia. URIs develop recurrently in 1- to 6-year-olds, and if reactive airways accompany the infection, the effect on the airway persists for 2 to 6 weeks.


Ultimately, the preoperative evaluation must weigh the inconvenience of rescheduling

against ignoring possible risks. If the decision is to

proceed with elective surgery, the infant should be

considered to have reactive airways.


The decision to cancel surgery on a child with an uncomplicated ORI always requires assessment from the viewpoint of a specific patient and family, a specific procedure, and a specific surgeon. A strict protocol for when to

cancel surgery is impractical. The patient's age, medical and anesthetic history, current physical examination, planned surgery (placement of tympanostomy tubes versus surgery for craniofacial repair), and anticipated postoperative care (need for mechanical ventilatory support) must be analyzed.


Ultimately, the preoperative evaluation must weigh the inconvenience of rescheduling against ignoring possible risks. If the decision is to proceed with elective surgery, the infant should be considered to have reactive airways.

Epiglottitis


Acute epiglottitis is an infectious disease caused by Haernopbilus infiuenzae type B. It can progress rapidly from a sore throat, to airway obstruction, to respiratory

failure and death if proper diagnosis and treatment are delayed. Patients are usually between 2 and 7 years of age, although epiglottitis has been reported in younger

children and adults.


Characteristic signs and symptoms of acute epiglottitis include

(1) a sudden onset of fever, dysphagia, drooling, thick muffled voice, and preference for the sitting position with the head extended and leaning forward (2) retractions, labored breathing, and cyanosis when respiratory obstruction is present.

Treatment


Direct visualization of the epiglottis should not be attempted in an awake patient because it could lead to airway compromise and death. Interactions with the patient should be kept to a minimum. Stimulation of the patient or the onset

of struggling during attempted treatment procedures may result in exacerbation of the airway obstruction. Induction of anesthesia is often accomplished with the

inhalation of sevoflurane (alternatively, halothanesevoflurane (alternatively, halothane) while maintaining spontaneous ventilation.


It is important to secure the airway without stimulating the reactive airway.

An emergency airway cart and tracheostomy tray should be available and open, with appropriate personnel present should an emergency surgical airway be needed.


Postoperative management takes place in the intensive care unit and consists of continued observation and radiographic confirmation of tracheal tube placement. Tracheal extubation is usually attempted 48 to 72 hours

later when a significant leak around the endotracheal tube is present and visual inspection of the larynx by flexible fiberoptic bronchoscopy confirms a reduction in swelling of the epiglottis and surrounding tissue.
