Anesthesia: Thyroid and Parathyroid

Thyroid and
Parathyroid Disorders
Anesthetic
Considerations
Moderated by Dr. Omar Ababneh
Presented by Bashar Mudallal

TESTS NORMAL
VALUES
INCREASED DECREASED
T4 60-120 nmole/L
-Hyperthyroidism
-Thyroditis
-Early hepatitis
-Pregnancy
-Oestrogen therapy
-Exogenous T4
-Hypothyroidism
-Androgens
-Salicylates
-Sulphonamides
T3 0.92-3 nmole/L Hyperthyroidism
-Hypothyroidism
-Cirrhosis
-Uraemia
-Malnutrition
TSH 0.25-8micIU/L Primary
hypothyroidism
Hyperthyroidism

nActio os of maj r calcium regulatin g hormones
HORMONE BONE KIDNEY INTESTINE
PTH
Increase
resorption of
calcium and
phosphate
 Incr. reabsorption of
calcium
 Decr. reabsorption of
phosphate
 Incr. conversion of
25OHD3
 to 1,25(OH) 2 D3
No direct
effect
Calcitonin
Decr.
Resorption of
calcium &
phosphate
Decr. Reabsorption of
calcium & phosphate
No direct
effect
VtD
Maintains
calcium
transport
system
Decr. Reabsorption of
calcium
Incr. reabsorption
of calcium &
phosphate

Hyperthyroidism
and
Thyrotoxicosis

Thyroid Storm
 Thyroid (or thyrotoxic) storm is an acute,
life-threatening syndrome due to an
exacerbation of thyrotoxicosis.
 It is now an infrequent condition because of
earlier diagnosis and treatment of thyrotoxicosis
and better pre- and postoperative medical
management.
 The incidence of thyroid storm currently
may be as low as 0.2 cases/100,000
population.

Factors That May Precipitate
Thyroid Storm
 Infections
 Acute Illness such as acute myocardial infarction,
stroke, congestive heart failure, trauma, etc.
 Non-thyroid surgery in a hyperthyroid patient
 Thyroid surgery in a patient poorly prepared for
surgery
 Discontinuation of anti-thyroid medications
 Radioiodine therapy
 Recent use of iodinated contrast
 Pregnancy particularly during labor and delivery

Clinical Manifestations of
Thyroid Storm
 History of thyroid
disease
 Goiter/thyroid eye
disease
 High fever
 Marked tachycardia,
occasionally atrial
fibrillation
 Heart Failure
 Tremor
Sweating
Nausea and vomiting
Agitation/psychosis
Delirium/coma
Jaundice
Abdominal pain

 Classic features of thyroid storm include
fever, marked tachycardia, heart failure,
tremor, nausea and vomiting, diarrhea,
dehydration, restlessness, extreme
agitation, delirium or coma
 Fever is typical and may be higher than 105.8 F
(41 C).
 Patients may present with a true
psychosis or a marked deterioration of
previously abnormal behavior.
 Rarely thyroid storm takes a strikingly different
form, called apathetic storm, with extreme
weakness, emotional apathy, confusion, and
absent or low fever.

 Signs and symptoms of decompensation in organ
systems may be present. Delirium is one example.
 Congestive heart failure may also occur, with
peripheral edema, congestive hepatomegaly, and
respiratory distress.
 Marked sinus tachycardia or tachyarrhythmia, such
as atrial fibrillation, are common.
 Liver damage and jaundice may result from
congestive heart failure or the direct action of thyroid
hormone on the liver.
 Fever and vomiting may produce dehydration and
prerenal azotemia.
 Abdominal pain may be a prominent feature.
 The clinical picture may be masked by a secondary
infection such as pneumonia, a viral infection, or
infection of the upper respiratory tract.

 Death from thyroid storm is not as
common as in the past if it is promptly
recognized and aggressively treated in an
intensive care unit, but is still
approximately 10-25%
 In recent nationwide studies from Japan the
mortality rate was >10%. Death may be from
cardiac failure, shock, hyperthermia, multiple
organ failure, or other complications.
 Additionally, even when patients survive,
some have irreversible damage including
brain damage, disuse atrophy,
cerebrovascular disease, renal
insufficiency, and psychosis.

Pathophysiology
 Thyroid storm classically began a few hours after
thyroidectomy performed on a patient prepared for
surgery by potassium iodide alone.
 Many such patients were not euthyroid and would not be
considered appropriately prepared for surgery by current
standards.
 Exacerbation of thyrotoxicosis is still seen in patients
sent to surgery before adequate preparation, but it is
unusual in the anti-thyroid drug-controlled patient.
 Thyroid storm occasionally occurs in patients operated
on for some other illness while severely thyrotoxic.
 Severe exacerbation of thyrotoxicosis is rarely seen
following 131-I therapy for hyperthyroidism; but some of
these exacerbations may be defined as thyroid storm.

 Thyroid storm appears most commonly following
infection, which seems to induce an escape
from control of thyrotoxicosis. Pneumonia, upper
respiratory tract infections, enteric infections, or
any other infection can cause this condition.
 Interestingly, serum free T4 concentrations were
higher in patients with thyroid storm than in
those with uncomplicated thyrotoxicosis, while
serum total T4 levels did not differ in the two
groups, suggesting that events like infections
may decrease serum binding of T4 and cause a
greater increase in free T4 responsible for storm
occurrence.
 Another common cause of thyroid storm is a
hyperthyroid patient suddenly stopping their anti-
thyroid drugs.

Diagnosis and Differential
 Diagnosis of thyroid storm is made on
clinical grounds and involves the usual
diagnostic measures for thyrotoxicosis.
 A history of hyperthyroidism or physical
findings of an enlarged thyroid or
hyperthyroid eye findings is helpful in
suggesting the diagnosis.
 The central features are thyrotoxicosis,
abnormal CNS function, fever, tachycardia
(usually above 130bpm), GI tract symptoms,
and evidence of impending or present CHF.

 There are no distinctive laboratory
abnormalities.
 Free T4 and, if possible, free T3 should be
measured. Note that T3 levels may be
markedly reduced in relation to the
severity of the illness, as part of the
associated “non-thyroidal illness
syndrome”.
 As expected, TSH levels are
suppressed. Electrolytes, blood urea
nitrogen (BUN), blood sugar, liver
function tests, and plasma cortisol
should be monitored.

 While the diagnosis of thyroid storm remains
largely a matter of clinical judgment, there are
two scales for assessing the severity of
hyperthyroidism and determining the
likelihood of thyroid storm.
 Recognize that these scoring systems are
just guidelines and clinical judgement is still
crucial.
 Data comparing these two diagnostic
systems suggest an overall agreement, but a
tendency toward under-diagnosis using the
Japanese criteria.
 Unfortunately, there are no unique laboratory
abnormalities that facilitate the diagnosis of
thyroid storm.

Burch-Wartofsky
Point Scale for the
Diagnosis of
Thyroid Storm

Japanese Thyroid
Association
Criteria for Thyroid
Storm

Therapy
 Thyroid storm is a medical emergency that has
to be recognized and treated immediately.
 Admission to an intensive care unit is usually
required.
 Besides treatment for thyroid storm it is essential
to treat precipitating factors such as
infections.
 As would be expected given the rare occurrence of
thyroid storm there are very few randomized
controlled treatment trials and therefore much of
what is recommended is based on expert opinion.

Follow-up
 Antithyroid treatment should be continued until
euthyroidism is achieved, when a decision
regarding definitive treatment of the hyperthyroidism
with antithyroid drugs, surgery, or 131-I therapy can
be made. Rarely urgent thyroidectomy is performed
with antithyroid drugs, iodide, and beta blocker
preparation.
 Prevention of thyroid storm is key and involves
recognizing and actively avoiding common
precipitants, educating patients about avoiding
abrupt discontinuation of anti-thyroid drugs, and
ensuring that patients are euthyroid prior to elective
surgery and labor and delivery.

Myxedema
 Myxedema coma is a severe and life-
threatening form of decompensated
hypothyroidism with an underlying
precipitating factor.
 The mortality rates may be as high as 25–
60% even with best possible treatment
 At present there are over 300 cases
reported in literature

Pathophysiology
 Usually a precipitating event disrupts
homeostasis which is maintained in
hypothyroid patients by a number of
neurovascular adaptations.
 These adaptations include chronic
peripheral vasoconstriction, diastolic
hypertension, and diminished blood
volume, in an attempt to preserve a
normal body core temperature.

Pathophysiology
 Homeostasis might no longer be
maintained in severely hypothyroid
patients if blood volume is reduced any
further (e.g. by gastrointestinal bleeding or
the use of diuretics),
 if respiration already compromised by a
reduced ventilatory drive is further
hampered by intercurrent pulmonary
infection, of if CNS regulatory mechanisms
are impaired by stroke, the use of
sedatives, or hyponatremia.

Diagnosis and Differentials
The three key features of myxedema coma are:
 Altered mental status. Usually somnolence and lethargy have
been present for months. Lethargy may develop via stupor into a comatose
state. There may have been transient episodes of reduced consciousness
before a more complete variety develops.
 Defective thermoregulation: hypothermia.The lower the
temperature, the worse the prognosis. Please check the ability of the
thermometer to accurately measure decreased temperatures (automatic
thermometers may not register frank hypothermia). Fever may be absent
despite infectious disease. With cold weather the body temperature may
drop sharply. Myxedema coma mostly develops during winter months.
 Precipitating event. Look for cold exposure, infection, drugs
(diuretics, tranquillizers, sedatives, analgesics), trauma, stroke, heart failure,
gastrointestinal bleeding.The typical patient is an older woman with altered
consciousness, presenting in wintertime. There is often a historyof
hypothyroidism, neck surgery or radioactive iodine treatment.

 Physical examination may reveal
hypothermia, hypoventilation, hypotension,
bradycardia, dry coarse skin, macroglossia,
and delayed deep-tendon reflexes. Absence
of mild diastolic hypertension in severely
hypothyroid patients is a warning sign of
impending myxedema coma.
 Laboratory examination may reveal
anemia, hyponatremia, hypoglycaemia,
hypercholesterolemia, and high serum
creatine kinase concentrations. Most patients
have low serum FT4 and high serum TSH.
Serum TSH can be low or normal, however,
due to the presence of central hypothyroidism
or the nonthyroidal illness syndrome.

Therapy
 Myxedema coma is a medical
emergency. Early diagnosis, rapid
administration of thyroid hormones
and adequate supportive measures
(Table) are essential for a successful
outcome.
 The prognosis, however, remains
poor with a reported mortality
between 20% and 50%.

Follow-up
 In case treatment was initiated with
intravenous T4 but after 24 hours the
patient is still comatose or vital functions
have not improved, iv administration of T3
should be considered.
 T3 should be discontinued and replaced
by T4 once circulation and respiration
have been stabilized.
 Intravenous administration of thyroid
hormones is replaced by oral
administration when the patient is fully
awake.

Introduction
 Thyroidectomy is the commonest endocrine
surgical procedure being carried out
throughout the globe.
 Majority of these patients have deranged thyroid
functions and sometimes may have even malignant
changes in the thyroid gland.
 The commonest implications during such
procedures involve the management of a
potential difficult airway, especially in cases of
retrosternal goiter, and an enlarged thyroid gland
compressing over the trachea for a prolonged
duration

Introduction
 Cardiac complications are equally challenging as
also the presence of various co-morbidities which
make the task of anesthesiologist extremely difficult.
 The complexity of surgical intervention also adds to
these existing challenges as the procedure may vary
from simple excision of a thyroid nodule to removal of a
large gland which may have a retrosternal extension
 Moreover, there always exists a potential risk of
uncontrolled hemorrhage from a vascular injury as
the major vessels lie in the vicinity of thyroid gland
and sometimes from the injury to the thyroid vessels
itself.

PRE-OP ASSESSMENT
 The primary goal, in patients presenting
for thyroid surgery, is to ensure a
euthyroid state.
 Besides thyroid hormonal levels, huge
emphasis is given to the assessment of
any potential difficult airway
management.

History
 Elicitation of history should include symptoms
related to hyperthyroidism, hypothyroidism
and co-morbid medical diseases.
 A large-sized goiter present for a prolong
duration makes the patient a potential candidate
for developing tracheomalacia.
 History should also include any difficulties
encountered during normal breathing and
respiration such as dyspnea, orthopnea,
dysphagia, stridor or breathlessness on
assuming supine position.

History
 Specifically, such patients should be
enquired about any endocrine disorder or
symptoms related to autonomic nervous
system dysfunction as there is a potential
probability of having associated multiple
endocrine neoplasia (MEN) syndrome.
 A rapid increase in the size of the goiter may be
due to either hemorrhage or in rare cases due to
rapidly enlarging malignancy that can cause
airway management difficulty.

Clinical and Physical
Examination
 It involves a multidisciplinary approach as thyroid
disease can be associated with various
complexities.
 The active role of endocrinologist, surgeon,
cardiologist, radiologist and anesthesiologist
during pre-op examination warrants a closely
coordinated team effort for precise diagnosis of
the degree of thyroid derangement and other co-
morbidities.

Signs of Deranged Thyroid
Function
 The main focus during this period is on
the presence or absence of signs
related to thyroid dysfunction,
namely hyperthyroidism and
hypothyroidism.
 Equally significant is the presence of
other co-morbid diseases such as
cardio-respiratory and other
associated endocrine disorders

Signs of Tracheal Compression
and Vocal Cords Palsy
 Examination of goiter should include the size,
consistency, duration and extent of enlargement.
 Fixed and hardness of the gland points toward
malignancy, while inability to feel the lower
border of thyroid gland indicates retrosternal
extension.
 The retrosternal extension of a large thyroid gland
may cause superior venocaval obstruction
syndrome, pleural and pericardial effusion and
Horner's syndrome due to compression effect on
the surrounding vital structures

Airway evaluation
 Airway examination should include
assessment of neck movements
in all planes (especially atlanto-
axial flexion and extension),
estimation of thyro-mental
distance, any protruding incisors,
protruding or retrognathic
mandible and Mallampatti
grading.

Investigations and lab findings
 Routine investigations should
include hemoglobin (Hb), white
blood cell count, platelet count,
serum electrolytes including serum
calcium, thyroid function tests,
renal function tests, chest X-ray, X-
ray antero-posterior and lateral
view of neck and ECG

ENT examination
 Indirect laryngoscopy should
preferably be carried out by an ENT
specialist as 3-5% of population
invariably has unilateral paralysis of
vocal cords.
 The presence of an ENT surgeon in
the Operation Theater is also essential
as there can be need for establishing a
definite surgical airway during the
induction period.

Radiological investigations
 In case of a very large-sized thyroid
gland and retrosternal extension,
computed tomography (CT) scan or
magnetic resonance imaging (MRI) is
preferable to delineate the exact
location and extension.
 The diagnosis of tracheal stenosis is
possible with spiral CT scan.

Endocrinologist's and
cardiologist's consultation
 The pre-op examination by an endocrinologist
and a cardiologist is of immense significance as
minute but important findings can be missed by
the surgeon, physician and the attending
anesthesiologist, which can have significant
impact on the surgical outcome.
 Though pulmonary function tests are not required
in majority of cases, they can be useful adjuncts
in cases of large thyroid gland or with retrosternal
extension so as to elicit any fixed upper airway
obstruction.

PRE-OP
PREPARATION AND
PREMEDICATION

Elective Surgery
 The main goal during any elective thyroid surgery is
the pre-op optimization of thyroid functions and
ensuring normal thyroid hormonal levels.
 Though propylthiouracil and methimazole have been
used extensively, carbimazole is the drug of choice in
preparing a hyperthyroid patient for the elective
surgery.
 The increased vascularity of thyroid gland by carbimazole,
however, exposes the patient to potential risks of higher
bleeding during the surgical procedure.
 Also, decreased WBC count as a result of carbimazole
therapy makes the patient vulnerable to numerous
infections during post-op period.

Elective Surgery
 Previously, potassium iodide was also used to render
the patient euthyroid, but this intervention takes a
very long time, usually 4-6 weeks.
 Currently, β-blockers are extensively used as
supplement to carbimazole to achieve cardiovascular
stability
 Failure to achieve these normal hormonal balances
can lead to over administration of anesthetic agents
as well as potential high risk of cardiovascular
complications like atrial fibrillation, exaggerated
hypertension and thyroid storm

Elective Surgery
 Patients with established hypothyroidism have
decreased metabolic rate and a decreased
capacity to metabolize the drugs which can
prolong the recovery from the effects of anesthetic
agents.
 Thyroxine is usually administered in a titrated
manner to normalize the thyroid function as the
pre-op higher levels of exogenous hormones can
cause peri-op cardiac complications like ischemia
and infarction due to imbalance between oxygen
demand and supply ratio

Elective Surgery
 The clinical manifestations of
hypothyroidism which can have
significant implications for an
anesthesiologist include depressed
myocardial function, impaired
baroreceptor reflex mechanism,
depressed ventilatory drive, decreased
plasma and RBC volume,
hypoglycemia and impaired hepatic
metabolism

Emergency Surgery
 In case of emergency surgical procedure,
rapid preparation of the patient includes
administration of β-blockers,
corticosteroids, anti-thyroid drugs and
iodine.
 The administration of β-blockers should be judicious
in lieu of potential risk of congestive cardiac failure
precipitation, bronchospasm in chronic obstructive
pulmonary disease (COPD) patients and
hypoglycemia in diabetic patients. Pre-op
administration helps in tiding over any possible
adrenal gland insufficiency.

Emergency Surgery
 Premedication is usually avoided in these
patients because of potential difficult airway
scenario and any possible respiratory obstruction.
 However, H-2 blockers like ranitidine and Oral
sodium citrate solution are safe along with
metoclopramide when administered
preoperatively.
 A difficult airway trolley should be made ready
and an ENT surgeon should be requested to
scrub before induction of anesthesia.

Administration of Anesthesia
 The practice of superficial and deep cervical
plexus blockade as well as cervical epidural
anaesthesia are not recommended anymore as
these techniques are invariably associated with
potential risk of complications such as inadequate
anesthesia or wearing of the effect of local
anesthetics and cardio respiratory arrest.
 In the present day practice of anesthesiology
bounded by medico-legal restrictions, general
anesthesia with endotracheal intubation is the
only safest approach for such delicate
procedures.

 The routine uses of glycopyrrolate and
atropine as a part of premedication during
thyroid surgery can be immensely helpful as
it can dry up the secretions and also test
the adequacy of anti-thyroid treatment.
 Pre-oxygenation with 100% oxygen
enhances the functional residual volume
and thus can provide enough time for
securing the access to difficult airway

 Shorter acting opioids such as fentanyl,
remifentanyl, sufentanyl should preferably
be used but the limited availability of these
drugs is a major drawback.
 Currently, role of dexmedetomidine is
increasingly acquiring significant
dimensions in regional and general
anaesthesia practice as it can greatly
decrease the dose of opioids and
anaesthetic agents when used as an
adjuvant

 Total intravenous anesthesia
(TIVA) has become increasingly
popular.
 Ever since its introduction into clinical
practice, propofol has become an
inseparable part of TIVA because of its
excellent clinical characteristics and
pharmacological actions such as rapid
onset, rapid recovery and anti-emetic
action.

 Propofol is the drug of choice in a dose of
2 mg/kg for induction of anesthesia.
 In a difficult airway scenario,
succinylcholine remains the drug of
choice, but ideally vecuronium is the
preferred muscle relaxant because of its
cardio-stability characteristics.
 The synergistic actions with opioids further widen
the scope of propofol and fentanyl combination
when used as a component of TIVA

 The nature of surgery warrants a free space around
the patients’ head end for a smoother procedure and
free movement of the assistants.
 As such, there are chances that a simple PVC tube can
get kinked under the drapes.
 Therefore, either an armored endotracheal tube
(ETT) or Ring, Adair and Elwyn (RAE) tube (North
Pole) is the preferred device for securing the airway
as they have minimal chances of kinking and causing
respiratory obstruction.
 Whichever ETT is used, it should be advanced beyond the
point of extrinsic compression

Airway Management
 Availability of fibreoptic bronchoscope
eases the pressure to a large extent on the
attending anesthesiologist.
 The relaxation caused by the anesthetic
agents and muscle relaxants may lead to
obstruction of the airway which can
present with marked stridor initially during
induction of anesthesia and inability to
ventilate partially or completely with face
mask after administration of general
anesthesia.

Airway Management
 Such difficult scenarios can be encountered in
malignancy of thyroid gland as it causes a lot of
fibrosis and tethering of soft tissue structures,
thereby making laryngoscopic view extremely
difficult which emphasizes the role of fibreoptic
bronchoscopy.
 In difficult situations, laryngeal mask airway (LMA)
can be used for ventilation, but for thyroid surgery,
its utility is doubtful as there can be compression
or deviation of trachea, retrosternal extension of
goiter, abnormal vocal cord movement and
suspected malignancy which can pose difficulties
in securing airway access.

Positioning
 The surgical access warrants maximum exposure of
thyroid gland which can be achieved by placing a
padded ring under the head of the patient and a rolled
sheet under the shoulders.
 The administration drugs necessitate an easy access to
intravenous line which can be made possible with the
use of extension tubing.
 All patients and especially those with
hyperthyroidism having proptosis and exopthalmos
should have their eyes covered with soft cotton
pad.
 The gravitational drainage of the blood from the surgical
site by a head-up position is a desirable feature and
should be routinely practiced.

Monitoring
 Monitoring during the perioperative period
should be intense and vigil as there are
potential chances of hemodynamic and
respiratory complications.
 Monitoring of temperature is also of
utmost significance as there are potential
risks of developing hyperthermia and
hypothermia in hyperthyroid and
hypothyroid patients, respectively, during
the peri-op and post-op periods.

Monitoring
 The prevention of stress response during
extubation is widely appreciable as it can avoid
any accidental hemorrhage from the wound site
due to bucking movements from the trachea
during reversal of anesthetic and muscle
relaxant effects.
 Dexmedetomidine has a significant role in
attenuation of stress response during these
procedures.
 The main disadvantage in carrying out
extubation in a deeper plane of anesthesia is the
possible failure of elicitation of vocal cord
movements.

Monitoring
 However, easy methods to detect such a
complication include asking the patient to speak the
letter “e” or the word “moon.”
 There is a high incidence of hyperthyroid
patients having associated myasthenia gravis,
and as such neuromuscular blockade should
be titrated and monitored with twitch monitor.
 Intra-op steroids are definitely helpful in
prevention of airway edema and reduce the
incidence of postoperative nausea and vomiting
(PONV) as well.

POST-OP PAIN AND
POSTOPERATIVE NAUSEA AND
VOMITING
 Numerous strategies can be employed for
prevention of post-op pain and include peri-op
administration of nonsteroidal anti-inflammatory
drugs, superficial cervical plexus blockade, post-op
infiltration of the wound site with local anesthetics
and/or injectable form of short acting opioids
postoperatively.
 These patients are known to have a high risk of
developing PONV.
 Different anti-emetics such as metoclopramide,
dexamethasone, ondansetron, palonosetron, and
so on can be used for prevention of PONV

POST-OP COMPLICATIONS
 Most of the dreaded events related to
thyroid surgery are manifested in the post-
op period, which include, but are not
limited to, the following:

Hemorrhage
 It is a common post-op complication and can cause
compression over the neck structures, leading to acute
airway obstruction.
 This is an acute emergency, and if it is not immediately
possible to shift the patient to Operation Theater, then
the sutures should be removed on the bedside to
relieve the airway obstruction.
 In such difficult situations, the airway can be secured by easy-
to-use devices such as LMA which can be used even by the
paramedics as well if properly trained.
 If time permits and the anesthesiologist is available, definite
airway in difficult situations can be secured even at the
bedside by endotracheal intubation.

Laryngeal Edema
 It is frequently caused by multiple
attempts at laryngoscopy during difficult
intubation or due to venous obstruction of
laryngeal vessels by an enlarging
hematoma.
 If edema leads to stridor, intubation with
ETT is mandatory

RLN Damage
 Damage to RLN can be caused by traction,
transaction, entrapment or ischemia and can
be permanent or transient.
 Manifestations of unilateral RLN palsy during
surgery include breathing difficulty,
hoarseness of voice and difficulty in
vocalization.
 Bilateral RLN palsy can lead to severe
stridor as a result of complete adduction of
vocal cords which can be treated only either
by tracheal intubation or by tracheostomy.

Superior Laryngeal Nerve
Damage
 Superior laryngeal nerve can get damaged in 3-5%
of the thyroidectomy procedures and the
commonest injury occurs to external branch of
superior laryngeal nerve, resulting in the paralysis
of cricothyroid muscle which causes alteration in
the quality of voice as the vocal folds fail to tense
during sound production.
 The injury can also occur to the internal branch of
superior laryngeal nerve which provides sensory
supply to mucosa of supraglottic region of larynx
and superior surface of vocal folds. As a result,
patient can develop dysphagia due to deranged
swallowing reflex.

Tracheomalacia
 A large-sized goiter compressing over the tracheal
structures for a long duration can cause pressure
atrophy and erosion of the cartilaginous tracheal rings.
 Post procedure, the tracheal wall loses the
surrounding support and can collapse in antero-
posterior direction leading to respiratory obstruction.
 On occasions, the conditions necessitate re-intubation
and possibly ventilatory support till the strength of
tracheal wall returns as the condition itself is self-limiting.
 Some anesthesiologists feel that a cuff leak test before
extubation can be a good indicator of possible post-op
respiratory dynamics, but it has not been fully
established in literature.

Hypoparathyroidism
 One of the operative complications of
thyroidectomy is injury to parathyroid
glands or its accidental removal which
can manifest in the form of acute
hypocalcemia in approximately 20% of the
patients.
 Features of hypocalcemia include peri-oral
tingling, mental confusion, muscular twitching,
seizures and tetany.
 Hypocalcemia can be elicited clinically by the
presence of Chvostek's and/or Trousseau's sign.

Hypoparathyroidism
 Cardiorespiratory manifestations of
hypocalcemia can occur in the form of
laryngospasm, cardiac irritability,
prolongation of QT interval and varied
arrhythmias.
 Hypocalcemia can be treated with oral supplements
if the Ca+ levels are >2 mmol/l, but has to be treated
with intravenous injection of either calcium
gluconate or calcium chloride if the levels fall below
2 mmol/l.
 Calcium chloride is more effective as it contains
three times more elemental calcium in a similar
volume of injection

Pneumothorax
 Though this complication is rare, it can occur during
the surgical resection of retrosternal goiter.
 On the operation table, any unwarranted episode of
hypoxemia, fall of pulse oxygen saturation, hypotension,
tachycardia, increased airway pressure, difficult
ventilation and absence of breath sounds on ventilation
should raise the suspicion of pneumothorax and should
be timely diagnosed and managed accordingly.
 The best treatment at the earliest detection of this
complication is either to relieve the pneumothorax by
placing a wide-bored needle into second anterior
intercostal space or to use a definite method, i.e. to go
for insertion of chest tube if tension pneumothorax
develops.

Thyroid storm
 The commonest cause for this complication is either a
severe illness or a poor preoperative preparation for
thyroid surgery.
 Though rarely seen in the era of medical advancement, it
can be fatal especially in the geriatric population if the
treatment is even slightly delayed.
 The main etiology is the hyperactive thyroid tissue
which is left as a remnant after sub-total
thyroidectomy.
 It can also occur during the intra-op period as a
result of secretion of colloid from the follicular cells,
which can be suspected from unexplained
tachycardia, hyperthermia and arrhythmias.

Thyroid storm
 The classical features of thyroid storm such as
abdominal pain, diarrhea, nervousness and
restlessness cannot be elicited and only
hyperthermia and cardiac arrhythmias can be
seen under general anesthesia.
 Treatment consists of emergency management of
tachycardia with β-blockers, cooling of the body by
decreasing the ambient room temperature, infusion of
cold fluids and draping in ice-cold packs, and
administration of steroids.
 Propylthiouracil and methimazole are used in fairly high
doses to decrease the thyroid hormone synthesis.

Introduction
 The elevation of serum calcium and inappropriate
increase in the levels of parathyroid hormones
constitute a constellation of symptoms of primary
hyperthyroidism.
 The endocrine, electrolyte and metabolic disturbances
resulting from such disorders can have a profound effect on
the normal human physiological milieu
 The classical features of hypercalcemia ‘moans,
groans and stones’ are rarely seen nowadays during
the initial clinical presentation owing to the early
diagnosis of hypercalcemia and the mainstay of
clinical presentation includes asymptomatic features
only

 The precautionary measures have to be taken
during administration of anesthesia as
thiopentone and volatile anaesthetic prolong
the QTc interval.
 Similarly few drugs like macrolides, quinolones,
antifungals like ketoconazole and fluconazole should
better be avoided during the peri-operative period as
they also have a potential to prolong QTc interval
 Renal scans and ultrasound are sometimes carried
out for diagnosis of renal stones which is very useful
for the formulation and planning for peri-operative
renal protection strategies when the patient is
administered anesthesia
Introduction

PRE-OP OPTIMIZATION
 Large number of geriatric patients that remain
undiagnosed and those who are reluctant to seek
medical advice, present invariably with advanced
stage of the disease process or sometimes
malignancy.
 The clinical symptomatology is diverse and may
include moderate to severe dehydration,
tachycardia, polyuria, anorexia, vomiting,
extreme weakness lethargy, and mental signs
and symptoms including psychosis which needs
thorough investigations
 In untreated cases the condition can deteriorate
rapidly and can progress to coma and collapse

The emergency therapeutic
interventions for optimization of
hypercalcaemia include:

Regional vs. general anesthesia
 The commonest indication for surgery in
patient with primary hyperparathyroidism
is hyperplasia of functional parathyroid
adenoma.
 Sometimes block dissection of neck is
mandatory in cases of locally advanced
malignancy of parathyroid gland.
 There is no specific technique which
can be considered absolutely superior.

 Regional anesthesia such as
superficial and deep cervical
plexus blockades have been used for
parathyroid surgery but such
techniques can be extremely
hazardous in light of inadequate
anesthesia and can cause numerous
complications ranging from
parasthesia to cardio-respiratory
arrest.

 There is a renewed interest in regional
anaesthesia with the advent of α-2
agonists such as clonidine and
dexmedetomidine which are being
extensively used as adjuvants with newer
local anaesthetics such as ropivacaine
and articaine in neuraxial anaesthesia.
 However, in modern day anesthesia
practice, GA with tracheal intubation
and muscle relaxants has been widely
accepted throughout the globe.

Premedication
 Routinely, combination of a benzodiazepine like
alprazolam and H2 antagonist ranitidine are
good premedication drugs when administered
orally a night before and on the morning of the
surgery.
 Sodium citrate is better alternative to H2
antagonists provided it is easily available.
Injection glycopyrrolate 0.2 mg ensures drying
of oro-pharyngeal secretions, which can be
immensely helpful during difficult airway
management.

Airway management
 Adequate pre-oxygenation with 100% oxygen
(O2) for at least 4-5 minutes is desirable to
ensure adequate pulmonary oxygen stores.
 One can use either armoured ETT or RAE
(Ring, Adair and Elwyn) tube but softness of
armoured tube makes its negotiation difficult
during airway management.
 In patients presenting for emergency surgery,
problems can be compounded by full stomach and
an altered mental status due to hypercalcemia that
makes the patient vulnerable to risk of aspiration.

Airway management
 The difficult airway can further compound the
problem and can lead to oesophageal
intubation and its associated complications.
 Patients with tendency for pathological
fractures due to prolonged hypercalcemia
should be dealt in a meticulous manner
during laryngoscopy as the chances for
quadriplegia are high due to unstable
cervical spine as a result of lytic lesions.

Airway management
 Cervical collar and manual in line
traction of the neck by an assistant is a
better option for preventing any dislocation
or possible fracture of the cervical
vertebrae.
 Availability of fibreoptic bronchoscope
eases the pressure while in difficult
situations laryngeal mask airway (LMA)
and combitube can also be used for
ventilation.

Anaesthetic techniques and
drugs
 Short acting opioids such as fentanyl,
remifentanyl, and sufentanyl are ideal
analgesics as they cause minimal respiratory
depression.
 Propofol is ideal for such procedures in a dose
of 2 mg/kg due to its rapid onset of action and
recovery due to short context-sensitive half
times, minimal side effects, prevention of post-
operative nausea and vomiting and dose
reduction in combination with opioids due to
synergism
 Etomidate can be used as an alternative if the patient
has pre-op cardiac involvement.

Anaesthetic techniques and
drugs
 Succinylcholine remains the drug of choice
especially in cases of anticipated difficult airway
management.
 Rocuronium is being increasingly used for rapid
sequence induction and intubation but the
limited availability of suggamedex for reversal
limits its utility during difficult airway
management.
 Total intravenous anesthesia (TIVA) has
become increasingly popular and propofol-
fentanyl combination has been extremely useful
for such procedures.

Positioning
 Positioning of neck should be done carefully as
there can be potential risk of accidental fractures
of cervical vertebrae.
 Extension of neck is usually done by resting the
head on a padded ring thus exposing the
parathyroid and thyroid gland to the maximum for
ease of surgery.
 Intravenous access if secured at upper limb should
have extension tubing attached as thoraco-
cephalic area is occupied by the surgeons and it will
be difficult to administer any medicine without
disturbing the surgical procedure

Positioning
 Eyes should be moistened by normal saline and
must be covered to prevent any corneal dryness
and/or abrasion especially in patients with
exopthalmos.
 A head-up position is preferable as it
enables the gravitational drainage of
blood and decrease the vascularity of
gland thus easing the surgical
conditions.

Intra-op management and
monitoring
 Peri-operative monitoring of non-invasive
blood pressure, pulse oximetry, ECG with lead II
and V5, temperature, end tidal carbon di-oxide
(EtCO2) and oesophageal stethoscope are
essential.
 Blood should be arranged or at least a cross
match should be done before the
commencement of procedure as the risk of
hemorrhage is always there due to confluence of
so many vessels.
Ambient room temperature has to be maintained
throughout the procedure to make surgical

monitoring
 Intra-op steroids are definitely helpful in
prevention of airway edema and its co-
administration with palonosetron reduces
the incidence of post-operative nausea
and vomiting (PONV).
 One big concern during parathyroid
surgery is the delay caused by frozen
section examination for which anesthesia
has to be maintained for unduly long
periods.
 Pre-op dialysis has a definite role during the surgery for

monitoring
 Platelet count and coagulation studies
should be done as dialysis and alfacalcidol
administration can cause platelet
dysfunction.
 Methylene blue should be used carefully and the
dose should not exceed 5 mg/kg as it can
significantly interfere with pulse oximetry.
 Deranged electrolyte balance especially of
calcium can interfere with cardiac conduction
disturbances and myocardial contractility
 Renal protection strategies should be employed
during peri-op period and should continue in

monitoring
 Muscle relaxant should be used in titrated
manner as the associated muscle weakness
warrants smaller dose of non-depolarizers.
 Moreover, the degree of muscle blockade should
be assured with train of four stimulations
during recovery from anesthesia so as to
prevent any potential respiratory compromise.
 However, the elevated calcium level can also
antagonize the action of non-depolarizers to
some extent.

Post-op anaesthetic
management
 It is imperative to proceed with smooth process
of extubation so as to avoid any stress
response and accidental hemorrhage from the
operative site.
 Hypercalcaemia may cause inadequate reversal
due to unpredictable augmentation of non-
depolarizing neuromuscular blockade, thus
possibly leading to post-operative hypoxemia
and respiratory obstruction

Post-op anaesthetic
management
 Use of train of four stimulations can be of
immense significance to monitor the degree of
neuromuscular blockade not only during the
extubation phase but is also helpful in titrating
the doses of muscle relaxants during the intra-
op period.
 Dexmedetomidine is commonly used in our set-
up in a dose of 1 μg/kg/hr during peri-op period
and it allows not only smooth extubation but also
decreases the dose of anesthetic and analgesic
agents during the peri-op period as well as
reduction in the incidence of shivering.

Post-op anaesthetic
management
 Dexmedetomidine is very effective agent in suppression
of stress response also before intubation when given in
infusion doses of 1 μg/kg, 15-20 minutes before
induction of anesthesia
 Though extubation in a deeper plane of
anesthesia is a more desirable feature but it will
not help in elicitation of any vocal cord
movement as perceived with indirect
laryngoscopy.
 Extubation should be carried out in a fully
awake state and after establishing a regular
breathing pattern with adequate tidal volume
and muscle strength.

 Bleeding: Post-operative episode of bleeding and
subsequent development of hematoma can cause
respiratory obstruction. Therefore, all the dressings
should be checked thoroughly before the patient is
shifted to their respective wards from the recovery area.
 Metabolic abnormalities: Hypophosphatemia,
hypomagnesemia, and hypokalemia can prove
catastrophic during post-op period and should be
rectified at the earliest. The combined picture projects a
constellation of clinical symptomatology such as cardiac
failure, dysarrhythmias, neuromuscular irritability
hemolysis, platelet dysfunction, and leucocyte
dysfunction

 Hypocalcemic tetany: It occurs due to drastic
reduction in post-operative serum calcium levels four to
five days post-operatively and is clinically manifested by
laryngeal spasms, seizures, and presence of Chvostek's
and Trousseau's sign.
 Recurrent laryngeal nerve (RLN) injury:
Unilateral RLN nerve injury is mostly asymptomatic as
there occurs compensatory over adduction of the
uninvolved cord and is typically characterized by the
development of hoarseness of voice. Unopposed
adduction of the cord can occur during bilateral RLN
injury and leads to closure of glottis. Endotracheal
intubation is a temporary relief measure and
tracheostomy is a definite long term preventive measure.

 Soft tissue trauma and edema: It
can progress to bullous glottic edema involving
the glottis and the pharynx. The onset and origin
of this complication remains controversial with
no definite preventive measures.
 Respiratory obstruction:
Respiratory obstruction can occur due to
enlarging hematoma from the wound site
bleeding, bilateral recurrent laryngeal nerve
injury, bullous glottis edema and metabolic
abnormalities.

 Renal complications: The chances of
renal dysfunction are high in patients who already
have some renal disease associated with
hypercalcemia pre-operatively.
 Post-op pain: Numerous techniques and
drugs are available nowadays to alleviate even a
high intensity pain. Pre-emptive analgesia and
patient controlled analgesia are the new dimensions
in the pain relief category which are getting very
popular at present.

Anesthetic management of
hypoparathyroidism
 Patients with hypoparathyroidism are
usually managed conservatively unless
they present with some acute surgical
emergency.
 In such situations, patients have to be
urgently optimized by laboratory
estimation of serum calcium, phosphate
and magnesium levels, which have to be
measured regularly during the post-op
period as well

hypoparathyroidism
 The symptomatic hypocalcaemia can be
treated with either intravenous
administration of calcium gluconate or
calcium chloride depending upon the
degree of hypocalcaemia.
 Though QTc interval in ECG is a good diagnostic
tool of the serum calcium levels but its
interpretation is also not a foolproof method of
either estimation or treatment of hypocalcaemia

hypoparathyroidism
 The anesthetic techniques are similar to other
parathyroid surgical procedures with an
emphasis on prevention of respiratory
alkalosis by avoiding hyperventilation and
monitoring of EtCO2, as it can precipitate
hypocalcemia by decreasing levels of ionized
calcium.
 Newer drugs have been in experimental stages, such as
calcimimetics, which enhance the sensitivity of calcium
sensing receptors.
 Such drugs can hold a future promise in the
management of parathyroid disorders and can possibly
avoid the risky surgical interventions.

Anesthesia: Thyroid and Parathyroid

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