1. Anesthesia In Patient with Respiratory
Diseases
Dr. Radhwan H. AL-Khashab
Consultant anaesthesia & ICU
2021
2. Introduction
Patients with respiratory diseases account for most common
challenges for the anesthesiologist during daily works.
Preoperative pulmonary impairment are associated with more
marked intraoperative alterations in respiratory function and
higher rates of postoperative pulmonary complications.
3. COPD is currently the 4th leading cause of death in the world
COPD is projected to be the 3rd leading cause of death by 2020
More than 3 million people died of COPD in 2012 accounting
for 6% of all deaths globally.
4. Preoperative risk factors
Patients related:
1. Age > 60 years.
2. ASA > II.
3. CHF.
4. Preexisting pulmonary dis.
5. Cigarette smoking.
Procedures related:
1) Emergency surgery.
2) Abdominal or thoracic surgery.
3) Prolonged duration of anaesthesia > 2.5 hr.
4) GA.
6. Preoperative investigations
There are many investigations used at preoperative time to assess the
tolerability for surgery & anaesthesia. Other than routine one we may
do :
Pulmonary function test (PFT) .
Blood gases.
Chest radiographs .
7. Can we do anything to reduce a
perioperative respiratory complications?
Smoking cessation
Cigarette smoke can acutely reduce airway ciliary function and
increase carbon monoxide levels.
* It may take weeks to months to find an objective improvement in
respiratory function after smoking cessation.
* The best evidence would suggest that at least two months is
required before smoking abstinence reduces the risk of pulmonary
complications .
8. Anesthetic technique :
The duration of anesthesia can impact the risk of respiratory
complications , significant reduction in mortality in those patients who
received neuraxial blockade or neuraxial blockade combined with
general anesthesia versus those who received general anesthesia
alone.
Pain control
Adequate postoperative pain control can reduce respiratory
complications in those incisions that are particularly painful (upper
abdominal and thorax). For patients undergoing laparotomy or major
thoracic surgery, a well-placed and functioning epidural catheter
provides superior pain relief when compared to intravenous narcotics .
9. Postoperative lung expansion
A variety of techniques are available for postoperative lung
expansion. This includes incentive spirometry, assisted
cough, percussion and vibration, deep suctioning and
ambulation.
10. Definition of COPD
Chronic obstructive pulmonary disease (COPD) is a spectrum of
diseases that includes emphysema, chronic bronchitis, and
asthmatic bronchitis. It is characterized by progressive increased
resistance to breathing. Airflow limitation may be caused by loss of
elastic recoil or obstruction of small or large (or both) conducting
airways.
The increased resistance may have some degree of reversibility.
Cardinal symptoms are cough, dyspnea, and wheezing
11. FEF is the flow of air coming out of lung during the middle portion
of a forced expiration.
The forced mid-expiratory flow (FEF 25-75%)value is a potentially
sensitive marker of obstructive peripheral air flow & it`s a useful
predictor for the development of COPD.
As the disease progresses, both forced expiratory volume in 1 s
(FEV1) and the FEV1/FVC (forced vital capacity) ratio are less than
70% of the predicted values.
Elevated airway resistance increase the work of breathing;
respiratory gas exchange is impaired because of
ventilation/perfusion imbalance.
Wheezing is a common finding and represents turbulent airflow.
12. Asthma
Asthma is a common disorder, affecting 5% to 7% of the population.
Manifested by episodic attacks of dyspnea, cough, and wheezing
which is the result of bronchial smooth muscle constriction, edema,
and increased secretions
The pathophysiology of asthma involves the local release of various
chemical mediators in the airway and, possibly, overactivity of the
parasympathetic nervous system.
Bronchoconstriction is the result of the subsequent release of
histamine; bradykinin; leukotrienes ; platelet-activating factor;
prostaglandins (PG) PGE2, PGF2, and PGD2; and neutrophil and
eosinophil chemotactic factors.
14. The parasympathetic nervous system plays a major role in
maintaining normal bronchial tone
Normal diurnal variation in tone is recognized in most
individuals with peak airway resistance early in the morning at
about 6:00 AM.
Vagal afferents in the bronchi are sensitive to histamine and
multiple noxious stimuli, including cold air, inhaled irritants, and
instrumentation (e.g. tracheal intubation).
Reflex vagal activation results in bronchoconstriction, which is
mediated by an increase in intracellular cyclic guanosine
monophosphate (cGMP).
15. Anesthetic Preoperative
Management
Preoperative Evaluation. Disease severity, effectiveness of current
therapy, and the potential need for additional therapy should be
assessed before surgery. Preoperative evaluation begins with a
clinical history to elicit the severity and characteristics of the patient’s
asthma. Auscultation of the chest to detect wheezing or crepitation is
important. Pulmonary function tests (especially FEV1) before and after
bronchodilator therapy may be indicated in patients scheduled for
major elective surgery. Measurement of arterial blood gases is
indicated if there is any question about the adequacy of ventilation or
oxygenation.
16. Asthmatic patients with active bronchospasm presenting for emergency
surgery should be treated aggressively whenever possible.
Supplemental oxygen, aerosolized B2 -agonists, and intravenous
glucocorticoids can dramatically improve lung function in a few hours.
In general, benzodiazepines are the most satisfactory agents for
premedication. Anticholinergic agents are not customarily given unless
very copious secretions are present or if ketamine is to be used for
induction of anesthesia.
17. The use of an H2- blocking agent (such as cimetidine, ranitidine, or
famotidine) is theoretically detrimental, since H2-receptor activation
normally produces bronchodilation.
Bronchodilators should be continued up to the time of surgery.
inhaled glucocorticoids, leukotriene blockers, mast-cell stabilizers,
theophyllines, and anticholinergics.
18. Intraoperative Management
Anesthetic
Induction and Maintenance of Anesthesia. A goal of induction and
maintenance of anesthesia is to suppress airway reflexes to
avoid bronchoconstriction in response to mechanical stimulation
of the airways.
a. Regional Anesthesia. The use of regional anesthesia when
the operative site is suitable for this may avoid instrumentation of
the airway and tracheal intubation.
b. General Anesthesia. Induction of anesthesia with propofol is
preferable to induction with thiopental, which is associated with a
higher incidence of wheezing. Ketamine may produce smooth
muscle relaxation and contribute to decreased airway resistance.
19. i. After unconsciousness is produced, the lungs are ventilated
with a volatile anesthetic agent to establish a depth of anesthesia
sufficient to permit tracheal intubation without precipitating
bronchospasm. Intravenous or intratracheal injection of lidocaine 1
to 1.5 mg/kg 1 to 3 minutes before tracheal intubation can be
helpful. Opioids may suppress the cough reflex and deepen
anesthesia. It may be preferable to use short acting opioids that
have limited risk of causing postoperative respiratory depression,
such as remifentanil (continuous infusion of 0.05 to 0.1
mcg/kg/min).
20. ii. LMA insertion is less likely than endotracheal intubation to result in
bronchoconstriction and may be a better method of airway management.
21. iii. Drugs with limited ability to evoke the release of histamine should be
selected.
Although all opioids have some histamine-releasing effects, fentanyl and
analogous agents have been used safely in asthma patients.
iv. Theoretically, antagonism of neuromuscular blockade with
anticholinesterase drugs could precipitate bronchospasm secondary to
stimulation of postganglionic cholinergic receptors in airway smooth
muscle. Bronchospasm does not predictably occur
after administration of anticholinesterase drugs, probably because of the
protective bronchodilating effects provided by the simultaneous
administration of anticholinergic drugs.
22. v. During mechanical ventilation in asthmatic patients, a slow
inspiratory flow rate provides optimal distribution of ventilation
relative to perfusion. Sufficient time for exhalation is necessary
to prevent air trapping. Humidification and warming of inspired
gases may be especially helpful.
vi. Maintenance of adequate hydration ensures less viscous
secretions in the airway.
23. vii. If possible, extubation should be performed while
anesthesia is still sufficient to suppress hyper reactive airway
reflexes.
When it is unwise to extubate the trachea before the
patient is fully awake, suppressing airway reflexes and/or the
risk of bronchospasm by administration of intravenous
lidocaine or pretreatment with inhaled bronchodilators
should be considered.
24. Airflow obstruction during expiration is apparent on
capnography as a delayed rise of the end-tidal CO2
value.
28. Chronic Bronchitis
Chronic bronchitis is defined by the presence of a productive cough
on most days of 3 consecutive months for at least 2 consecutive
years.
Secretions from hypertrophied bronchial mucous glands and
mucosal edema from inflammation of the airways produce airflow
obstruction.
Intrapulmonary shunting is prominent, and hypoxemia is common.
In patients with COPD, chronic hypoxemia leads to erythrocytosis,
pulmonary hypertension, and eventually right ventricular failure (cor-
pulmonale); this combination of findings is often referred to as the
blue bloater syndrome.
In the course of disease progression, patients gradually develop
chronic CO2 retention; the normal ventilatory drive becomes less
sensitive to arterial CO2 tension and may be depressed by oxygen
administration
29. Emphysema
Pathological disorder characterized by irreversible enlargement of
the airways distal to terminal bronchioles and destruction of alveolar
septa.
Significant emphysema is nearly always related to cigarette smoking.
Less commonly, emphysema occurs at an early age and is
associated with a homozygous deficiency of alpha 1-antitrypsin.
Loss of the elastic recoil that normally supports small airways by
radial traction allows premature collapse during exhalation
Patients characteristically have increases in RV, FRC, TLC.
30. Large cystic areas, or bullae, develop in some patients.
Increased dead space is a prominent feature of emphysema.
Arterial oxygen tensions are usually normal or only slightly
reduced; CO2 tension is also typically normal.
When dyspneic, patients with emphysema often purse their lips to
delay closure of the small airways—which accounts for the term
pink puffers that is often used.
31. Treatment of COPD
Treatment for COPD is primarily supportive.
The most important intervention is cessation of smoking.
Inhaled B2-adrenergic agonists, glucocorticoids, and ipratropium are
very useful
Exacerbations are often related to bouts of bronchitis, heralded by a
change in sputum; frequent treatment with broad-spectrum antibiotics
(e.g. ampicillin, tetracycline, sulfamethoxazole-trimethoprim) may be
necessary.
Hypoxemia should be treated carefully with supplemental oxygen.
32. Oxygen therapy can dangerously elevate PaCO2 in patients with
CO2 retention; elevating PaO2 above 60 mm Hg can precipitate
respiratory failure.
When cor-pulmonale is present, diuretics are used to control
peripheral edema.
33. Anesthetic Preoperative
Management
They should be questioned about recent changes in dyspnea,
sputum, and wheezing.
PFTs, chest radiographs, and arterial blood gas measurements
should be reviewed carefully.
In contrast to asthma, only limited improvement in respiratory
function may be seen after a short period of intensive preoperative
preparation.
preoperative interventions in patients with COPD aimed at
correcting hypoxemia, relieving bronchospasm, mobilizing and
reducing secretions, and treating infections may decrease the
incidence of postoperative pulmonary complications.
34. Smoking should be discontinued for at least 6–8 weeks before the
operation to decrease secretions and to reduce pulmonary
complications.
cessation of smoking for as little as 24 h has theoretical beneficial
effects on the oxygen-carrying capacity of hemoglobin
Preoperative chest physiotherapy (chest percussion and postural
drainage) and antibiotics for patients with a change in sputum are
beneficial in reducing secretions.
Bronchospasm should be treated with bronchodilators.
Patients with moderate to severe disease may benefit from a
perioperative course of glucocorticoids.
35. Anesthetic Intrao perative Management
Pre-oxygenation prior to induction of general anesthesia prevents
the rapid oxygen desaturation often seen in these patients.
The selection of anesthetic agents and general intraoperative
management are similar to those for asthmatic patients
ventilation should be controlled with small to moderate tidal
volumes and slow rates to avoid air trapping.
Humidified gases should be used if significant bronchospasm is
present and for long procedures (> 2 h).
Direct measurement of arterial oxygen tensions may be
necessary to detect more subtle changes in intrapulmonary
shunting.
36. Patients with pulmonary bullae are at high risk of developing
pneumothoraxes intraoperatively, particularly if ventilated with
positive pressure.
At the end of surgery, the timing of extubation should balance the
risk of bronchospasm with that of pulmonary insufficiency, but
evidence suggests that early extubation (in the operating room) is
beneficial.
Patients with an FEV1 below 50% are most likely to require a
period of postoperative ventilation, particularly following upper
abdominal and thoracic operations.
37. Bronchiectasis.
A chronic suppurative disease of the airways, bronchiectasis may
cause expiratory airflow obstruction similar to that seen with COPD.
1. Pathophysiology. Bacterial or mycobacterial infections are
presumed responsible for most cases of bronchiectasis.
2. Diagnosis. The history of a chronic cough productive of large
amounts of purulent sputum is highly suggestive of bronchiectasis.
Digital clubbing occurs in most patients with significant bronchiectasis.
Computed tomography (CT) provides excellent images of
bronchiectatic airways.
38. 3. Treatment. Bronchiectasis is treated with antibiotics and
postural drainage. Massive hemoptysis (>200 mL over a 24-hour
period) may require surgical resection of the involved lung.
4. Management of Anesthesia. A double-lumen endobronchial
tube may be used to prevent spillage of purulent sputum into
normal areas of the lungs. Nasal intubation should be avoided
due to high rates of chronic sinusitis.
39. Restrictive Pulmonary Disease
Restrictive pulmonary diseases are characterized by decreased
lung compliance.
Lung volumes are typically reduced, with preservation of normal
expiratory flow rates.
Both FEV1 and FVC are reduced, but the FEV1/FVC ratio is
normal.
Restrictive pulmonary diseases include many acute and chronic
intrinsic pulmonary disorders as well as extrinsic (extra
pulmonary) disorders involving the pleura, chest wall,
diaphragm, or neuromuscular function.
Reduced lung compliance increases the work of breathing,
resulting in a characteristic rapid but shallow breathing pattern.
41. Acute Intrinsic Pulmonary
Disorders
Acute intrinsic pulmonary disorders include pulmonary edema
(including the acute respiratory distress syndrome [ARDS]),
infectious pneumonia, and aspiration pneumonitis.
Reduced lung compliance in these disorders is primarily due to
an increase in extravascular lung water, from either an increase
in pulmonary capillary pressure or an increase in pulmonary
capillary permeability
Increased pressure occurs with left ventricular failure, whereas
fluid overload and increased permeability are present with
ARDS.
42. Anesthetic Preoperative
Management
In preparation for emergency procedures, oxygenation and
ventilation should be optimized preoperatively to the greatest
extent possible.
Fluid overload should be treated with diuretics; heart failure may
also require vasodilators and inotropes.
Persistent hypoxemia may require positive-pressure ventilation
and positive end-expiratory pressure (PEEP).
43. Anesthetic Intra operative Management
High inspired oxygen concentrations and PEEP may be required.
The decreased lung compliance results in high peak inspiratory
pressures during positive-pressure ventilation and increases the risk
of barotrauma and volutrauma.
Tidal volumes for these patients should be reduced to 4–8 mL/kg,
with a compensatory increase in the ventilatory rate (14–18
breaths/min), even if the result is an increase in end-tidal CO2
44. Airway pressure should generally not exceed 30 cm H2O.
a more sophisticated intensive care unit ventilator should be used in
such instances.
Aggressive hemodynamic monitoring is recommended.
45. Chronic Intrinsic Pulmonary
Disorders
also often referred to as interstitial lung diseases.
the disease process is generally characterized by an insidious
onset, chronic inflammation of alveolar walls and perialveolar
tissue, and progressive pulmonary fibrosis.
Causes include hypersensitivity pneumonitis from occupational and
environmental pollutants, drug toxicity (bleomycin and
nitrofurantoin), radiation pneumonitis, idiopathic pulmonary fibrosis,
autoimmune diseases, and sarcoidosis.
Chronic pulmonary aspiration, oxygen toxicity, and severe ARDS
can also produce chronic fibrosis.
46. Patients typically present with dyspnea on exertion and sometimes
a nonproductive cough.
Symptoms of corpulmonale are present only with advanced
disease.
Physical examination may reveal fine (dry) crackles over the lung
bases and, in late stages, evidence of right ventricular failure.
The chest radiograph progresses from a "ground-glass"
appearance to prominent reticulonodular markings and, finally, to a
"honeycomb" appearance.
Arterial blood gases usually show mild hypoxemia with
normocarbia.
PFTs are typical of a restrictive ventilatory defect
47. Anesthetic Preoperative Management
Preoperative evaluation should focus on determining the degree of
pulmonary impairment as well as the underlying disease process.
A history of dyspnea on exertion (or at rest) should be evaluated
further with PFTs and arterial blood gas analysis.
A vital capacity less than 15 mL/kg is indicative of severe
dysfunction (normal is > 70 mL/kg).
A chest radiograph is helpful in assessing disease severity.
48. Anesthetic Intraoperative Management
The management of these patients is complicated by a predisposition
to hypoxemia and the need to control ventilation to ensure optimum
gas exchange; anesthetic drug selection is generally not critical.
The reduction in FRC (and oxygen stores) predisposes these patients
to rapid hypoxemia following induction of anesthesia; their uptake of
inhalation anesthetics may also be accelerated.
Because these patients may be more susceptible to oxygen-induced
toxicity, particularly patients who have received bleomycin, the inspired
fractional concentration of oxygen should be kept to the minimum
concentration compatible with acceptable oxygenation (SpO2 of > 88–
92%).
High peak inspiratory pressures during mechanical ventilation increase
the risk of pneumothorax and should prompt smaller than normal tidal
volumes with a faster rate.
49. Extrinsic Restrictive Pulmonary Disorders
Extrinsic restrictive pulmonary disorders alter gas exchange by
interfering with normal lung expansion.
They include pleural effusions, pneumothorax, mediastinal
masses, kyphoscoliosis, pectus excavatum, neuromuscular
disorders, and increased intraabdominal pressure from ascites,
pregnancy, or bleeding.
Marked obesity also produces a restrictive ventilatory defect .
Anesthetic considerations are similar to those discussed for
intrinsic restrictive disorders.
50. Pulmonary Embolism
Pulmonary embolism results from the entry of blood clots, fat,
tumor cells, air, amniotic fluid, or foreign material into the venous
system.
Clots from the lower extremities (nearly always above the knee),
pelvic veins, or, less commonly, the right side of the heart are
usually responsible.
Venous stasis or hypercoagulability is often contributory in such
cases.
Pulmonary embolism can also occur intraoperatively in normal
individuals undergoing certain procedures.
51. Clinical manifestations of pulmonary embolism include sudden
tachypnea, dyspnea, chest pain, or hemoptysis.
Wheezing may be present on auscultation. Arterial blood gas
analysis typically shows mild hypoxemia with respiratory
alkalosis (the latter due to an increase in ventilation).
Cardiac signs include tachycardia and wide fixed splitting of the
S2 heart sound; hypotension with elevated central venous
pressure is usually indicative of right ventricular failure.
The electrocardiogram frequently shows tachycardia and may
show signs of acute corpulmonale
Pulmonary angiography is the most accurate means of
diagnosing a pulmonary embolism
52. The best treatment for pulmonary embolism is prevention.
Heparin (unfractionated heparin 5000 U subcutaneously every 12
h begun preoperatively or immediately postoperatively in high-risk
patients), oral anticoagulation (warfarin), aspirin, or dextran
therapy together with early ambulation can decrease the incidence
of postoperative emboli.
The use of high elastic stockings and pneumatic compression of
the legs may also decrease the incidence of venous thrombosis in
the legs but not in the pelvis or the heart.
Systemic anticoagulation prevents the formation of new blood clots
or the extension of existing clots. Heparin therapy is begun with
the goal of achieving an activated partial thromboplastin time of
1.5–2.4 times normal. Low-molecular-weight heparin (LMWH) is as
effective and is given subcutaneously at a fixed dose (based on
body weight) without laboratory monitoring.
53. LMWH is more expensive than unfractionated heparin but is
more cost-effective. In high-risk patients, LMWH is started
either 12 h before surgery, 12–24 h after surgery, or at 50%
the usual dose 4–6 h after surgery. All patients should start
warfarin therapy concurrent with starting heparin therapy, and
the two should overlap for 4–5 days. The international
normalized ratio should be within the therapeutic range on
two consecutive measurements at least 24 h apart before the
heparin is stopped. Warfarin should be continued for 3–12
months.
54. Anesthetic Preoperative
Management
Patients with acute pulmonary embolism may present in the operating
room for placement of a caval filter or, rarely, for pulmonary
embolectomy.
In most instances, the patient will have a history of pulmonary
embolism and presents for unrelated surgery; in this group of patients,
the risk of interrupting anticoagulant therapy perioperatively is
unknown.
If the acute episode is more than 1 year old, the risk of temporarily
stopping anticoagulant therapy is probably small. Moreover, except in
the case of chronic recurrent pulmonary emboli, pulmonary function
has usually returned to normal. The emphasis in the perioperative
management of these patients should be in preventing new episodes
of embolism
55. Anesthetic Intraoperative Management
Vena cava filters are usually placed percutaneously under local
anesthesia with sedation.
Patients may display enhanced sensitivity to the circulatory
effects of most anesthetic agents.
Decreased venous return during placement of the device can
precipitate hypotension.
Patients presenting for pulmonary embolectomy are critically ill.
They are usually already intubated but tolerate positive-pressure
ventilation poorly. Inotropic support is necessary until the clot is
removed.
They also tolerate all anesthetic agents very poorly. Small doses
of an opioid, etomidate, or ketamine may be used, but the latter
can theoretically increase pulmonary artery pressures.
Cardiopulmonary bypass is required.
56. Intraoperative Pulmonary
Embolism
Significant pulmonary embolism is a rare occurrence during
anesthesia.
Diagnosis requires a high index of suspicion. Air emboli are common
but are often overlooked unless large amounts are entrained.
Fat embolism can occur during orthopedic procedures; amniotic fluid
embolism is a rare, unpredictable, and often fatal, complication of
obstetrical delivery .
Thromboembolism may occur intraoperatively during prolonged
procedures.
The clot may have been present prior to surgery or may form
intraoperatively; surgical manipulations or a change in the patient's
position may then dislodge the venous thrombus. Manipulation of
tumors with intravascular extension can similarly produce pulmonary
embolism.
57. Intraoperative pulmonary embolism usually presents as
unexplained sudden hypotension, hypoxemia, or
bronchospasm.
A decrease in end-tidal CO2 concentration is also suggestive of
pulmonary embolism but not specific.
Invasive monitoring may reveal elevated central venous and
pulmonary arterial pressures.
Depending on the type and location of an embolism, a
transesophageal echocardiogram may be helpful.
If air is identified in the right atrium, or if it is suspected,
emergent central vein cannulation and aspiration of the air
may be lifesaving.
For all other emboli, treatment is supportive, with intravenous
fluids and inotropes. Placement of a vena cava filter should be
considered postoperatively.
58. Postoperative lung expansion
A variety of techniques are available for postoperative lung
expansion. This includes incentive spirometry, assisted cough,
percussion and vibration, deep suctioning and ambulation.
The use of postoperative incentive spirometry has been shown
to reduce postoperative respiratory complications