physiological changes in various position.pptx

DR.PRAVIN KALSARIYA
U/G/O DR.DHAVAL PATEL
PHYSIOLOGICAL CHANGES IN DIFFERENT
POSITION AND ITS SIDE EFFECTS DURING
ANAESTHESIA

Patient positioning is a major responsibility that is
shared by the entire operating room team. A
balance between optimal surgical positioning and
patient well-being is required.
Patient’s position during anesthesia care should
be natural- one that would be well tolerated if the
patient is awake and sedated.

PURPOSE OF DIFFERENT POSITION
►To provide optimal exposure to surgery.
►To promote comfort to the patient.
►To relive pressure on various part.
►To stimulate circulation.
►To provide proper body alignment.
►To perform surgical and medical intervention.

PHYSIOLOGICAL CHANGES RELATED TO CHANGE
IN BODY POSITION
Most changes are related to gravitational
effects on cardiovascular system and
respiratory system.
Changes in position redistribute blood within the
venous, arterial, and pulmonar y vasculature.

Most common with the least amount of harm.
Placed on back with legs extended and
uncrossed at the ankles.
Spinal column should be in alignment with
legs parallel to the bed and Head in line with
the spine and the face is upward.

 Arms either on arm boards
abducted <90 degrees to
minimize the likelihood of brachial
plexus injury.
 When arms are adducted, they
are usually held alongside the
body.
Associated arm position

WHEN TO USE SUPINE POSITIONING
 supine patient positioning is used for intracranial procedures
as well as procedures on the anterior surface of the body.
Also known as Dorsal Decubitus, procedures that typically
use the supine position include:
• Cardiac
• Colorectal
• Thoracic
• Abdominal
• Abdominothoracic
• Endovascular surgeries
• Laparoscopic surgeries
• Upper extremity surgeries including hand and wrist
• Lower extremity surgeries including hip, knee, foot, and ankle

CONCERNS IN SUPINE POSITION
 Greatest concerns are circulation and pressure
points
 Most Common Nerve Damage:
 Brachial Plexus: positioning the arm >90*.
 Radial and Ulnar: compression against the OR
bed, metal attachments.
 Peroneal and Tibial:Crossing of feet and
plantar flexion of ankles and feet.
 Vulnerable Bony Prominences:
(due to rubbing and sustained pressure)
 Occiput, spine, scapula, Olecranon,
Sacrum, Calcaneous

CARDIOVASCULAR CONCERNS
Cardiac output ↑ on assuming
supine position.
Venous blood from lower body
flows back To heart
↓
Stretches atrial wall
↓
Stroke volume ↑
↓
↑ blood pressure

Baroreceptor in arota via vagus
nerve
Baroreceptor in carotid sinus
via glossopharyngeal nerve
Little change in BP noted
(clinically normal BP observed
Increase para sympathomimetics activity
decrease HR and BP

In General anesthesia, induction agent, muscle
relaxation, positive pressure ventilation, and
neuraxial blockade all interfere with venous return
to the heart, arterial tone, and autoregulatory
mechanism.
Therefore, arterial blood pressure is often labile
immediately after the start of
anesthesia and during positioning.

• Positive-pressure ventilation
– ↑ mean intrathoracic pressure,
– ↓ venous return
– ↓ cardiac output
• Positive end-expiratory pressure increases
mean intrathoracic pressure further, as do
conditions associated with low lung compliance,
such as
– Airways disease
– Obesity
– Ascites

• As such , arterial blood pressure is often
particularly labile at induction and during patient
positioning. (It is crucial for the anesthesiologist to anticipate,
monitor, and treat these effects, and
to assess the safety of positional changes for each patient.)
• Interruptions in monitoring to facilitate positioning or turning of
the operating room table must be minimized during this
dynamic period.
• Patient positioning is always secondary to patient
safety.

Pulmonary Concerns
In an erect position.
-Abdominal contents & diaphragm move
caudally.
-FRC ↑ , TLC ↑.

Anesthetized person who are spontaneously breathing—
↓Tidal Volume
↓Functional residual capacity.
Positive pressure ventilation with muscle relaxation may ameliorate
ventilation perfusion mismatches under GA by maintaining
adequate minute ventilation.
Perfusion appears to follow a central-to-peripheral spectrum in
each lobe that is maintained with changes in cardiac output.
Also, gravity affects the preferential perfusion of the dependent
portions of the lungs.

Pressure alopecia:
Lumps, such as those caused by monitoring cable
connectors, etc, should not be placed under head padding
because they may create focal areas of pressure.
Backache :
as the normal lumbar lordotic curvature, particularly the tone
of the paraspinous musculature, is lost during general
anesthesia with muscle relaxation or a neuraxial block.
Bony ischemia:
Tissues overlying all bony prominences, such as the heels
and sacrum, must be padded to prevent soft tissue ischemia
owing to pressure, especially during prolonged surgery.
SIDE EFFECT’S

Peripheral nerve injury :(Ulnar neuropathy is the
most common lesion.)
Regardless of the position of the upper extremities,
maintaining the head in a relatively midline
position can help minimize the risk of stretch injury
to the brachial plexus.
limiting arm abduction in supine patient to less
than 90 degrees at the shoulder with the hand
and forearm either supinated or kept in neutral
position.

• Variations of the Supine Position
*Lawn chair position*
– It better tolerated by patients who are awake or
undergoing monitored anaesthesia care.
-- In addition, because the legs are slightly above
the heart, venous drainage from the lower
extremity is facilitated.
-- Also, the xyphoid to pubic distance is decreased,
reducing the tension on the ventral abdominal
musculature and easing closure of laparotomy
incisions.

Frog leg position
 A variation of supine in which the hips and knees
are flexed, and the hips are externally rotated and
sole of both foot near to middline each other.
 facilitates access to the perineum, groin, rectum,
and inner thigh.
► but the knees must be supported to avoid
stress and dislocation of the hips.

* Trendelenburg position *
* Reverse Trendelenburg position*
AND

• The Trendelenburg position has significant cardiovascular and respiratory
consequences.
– The head-down position
– Increases central venous, intracranial, and intraocular pressures.
• Prolonged head-down position also can lead to swelling of the face,
conjunctiva, larynx, and tongue with an increased potential for postoperative
upper airway obstruction.
• The cephalic movement of abdominal viscera against the diaphragm also
decreases functional residual capacity and pulmonary compliance.
(In spontaneously ventilating patients, the work of breathing increases.)

• In mechanically ventilated patients, airway pressures must be higher to
ensure adequate ventilation.
• The level of stomach also lies above the level of glottis. So,
Endotracheal intubation is often preferred to protect the airway from
pulmonary aspiration related to reflux and to reduce atelectasis.
• Because of the risk of oedema to the trachea and mucosa surrounding
the airway during surgeries in which patients have been in the
Trendelenburg position for prolonged periods, it may be prudent to
verify an air leak around the endotracheal tube or visualize the larynx
before extubation

 Reverse Trendelenburg position (head-up tilt) is often employed to facilitate
upper abdominal surgery by shifting the abdominal contents caudad.
 This position is increasingly popular because of the growing number of
laparoscopic surgeries.
 Caution is advised to prevent patients from slipping on the table, and more
frequent monitoring of arterial blood pressure m a y be prudent to detect
hypotension owing to decreased venous return.
 In addition, the position of the head above the heart reduces perfusion
pressure to the brain and should be taken into consideration w h e n
determining optimal blood pressure.
 In all positions in which the head is at a different level than the heart, the
effect of the hydrostatic gradient on cerebral arterial and venous pressures
should be carefully considered in terms of cerebral perfusion pressure.

Lithotomy position
The classic lithotomy position is
frequently used during
gynecologic, rectal, and urologic
surgeries.
The hips are flexed 80 to 100
degrees from the trunk, and the
legs are abducted 30 to 45
degrees from the midline

Initiation of the lithotomy position requires
coordinated positioning of the lower extremities by
two assistants to avoid torsion of the lumbar
spine.
Both legs should be raised together, flexing the
hips and knees simultaneously.
After the surgery, the patient must be returned to
the supine position in a coordinated manner. The
legs should be removed from the holders
simultaneously, knees brought together in the
midline, and the legs slowly straightened and
lowered onto the operating room table.

 When the legs are elevated, preload increases, causing a
transient increase in cardiac output and, to a lesser extent,
cerebral venous and intracranial pressure in otherwise healthy
patients.
 In addition, the lithotomy position causes the abdominal
viscera to displace the diaphragm cephalad, reducing lung
compliance and potentially resulting in a decreased tidal
volume.
 If obesity or a large abdominal m a s s is present (tumor, gravid uterus),
abdominal pressure m a y increase significantly enough to obstruct
venous return to the heart.
 the normal lordotic curvature of the lumbar spine is lost in the lithotomy
position, potentially aggravating any previous lower back pain.
 Lower extremity compartment syndrome may rarely occur.

Problem related to lithotomy position
1. Common peroneal nerve injury.(most common)branch of sciatic nerve.
2. Femoral nerve injury.
3. Oburator nerve injury.
4. Ischemic compartment syndrome.
The following characteristics of the lithotomy position are risk
factors for the development of compartment syndrome:
• Pressure on the lower legs due to fixation of the legs on a support
• Legs elevated above the level of the heart
• Venous obstruction in the inguinal region due to hip flexion

 The fixation of the legs produces increased external pressure, which subsequently
causes intracompartmental edema, thereby raising intracompartmental pressure
which may ultimately lead to compartment syndrome.
 Elevation of the legs above the level of the heart, lowers local tissue perfusion,
inducing hypoxia and producing edema or even tissue necrosis.In extreme cases,
rhabdomyolysis and compartment syndrome result.
 Oftentimes, the lithotomy position requires hip flexion of at least 90°. Venous
obstruction in the inguinal region may result, thereby lowering venous return,
which allows interstitial fluid to accumulate, causing edema and increased
compartment pressure.

The lateral decubitus position is used most
frequently for surgery involving the thorax,
retroperitoneal structures, or hip.
The patient’s head must be kept in a neutral position
to prevent excessive lateral rotation of the neck and
stretch injuries to the brachial plexus.
The dependent ear should be checked to avoid
folding and undue pressure.
It is advised to verify that the eyes are securely
taped before repositioning if the patient is asleep.

The dependent eye must be checked frequently for
 external compression.
Watch for compression of the dependent axillary
structures.
( the volume of pulse should be monitored in the
dependent arm for early detection of compression to
axillary neurovascular structures.)
Vascular compression and venous engorgement in
the dependent arm may affect the pulse oximetry
reading specially PI index and a low saturation
reading may be a late warning sign of compromised
circulation.

When a kidney rest is used, it must be properly
placed under the dependent iliac crest to
prevent inadvertent compression of the inferior
vena cava.
a pillow or other padding is generally placed
between the knees with the dependent leg
flexed to minimize excessive pressure on
bony prominences and stretch of low
extremity nerves.

The lateral decubitus position also is associated
with pulmonary compromise. In a patient who is
mechanically ventilated,
lateral weight of the mediastinum
disproportionate cephalad pressure of abdominal
contents on the dependent lung favors
overventilation of the nondependent lung
pulmonary blood flow to the under-ventilated
(dependent lung) increases owing to the
effect of gravity.
So it lead to ventilation-perfusion mismatch.

Used primarily for surgical access to the posterior fossa of the
skull, the posterior spine, the buttocks and perirectal area,
and the lower extremities.
As with the supine position, if the legs are in plane with the
torso, hemodynamic reserve is maintained.
Pulmonary function m a y be superior to the supine or lateral
decubitus positions if there is no significant abdominal
pressure and the patient is properly positioned.
The legs should be padded and flexed slightly at the knees
and hips. The head m a y be supported face- down with its
weight borne b y the bony structures or turned to the side.

 Both arms m a y be positioned to the patient’s sides a n d tucked in the neutral position
or placed next to the patient’s head on arm boards.
 Extra padding under the elbow is needed to prevent compression of the ulnar nerve.
 The arms should not be abducted greater than 90 degrees to prevent excessive
stretching of the brachial plexus.
 elastic stockings an d active compression devices are need ed for the lower
extremities to minimize pooling of the blood, especially with a n y flexion of the body.
 When general anesthesia is planned, the patient is first intubated on the stretcher, and
all intravascular access is obtained as needed.
 The armored endotracheal tube is well secured to prevent dislodgment and loosening
of tape owing to drainage of saliva w h en prone.
 With the coordination of the entire operating room staff(minimum of 5), the patient is
turned prone onto the operating room table, keeping the neck in line with the spine
during the move.

●The anesthesiologist is primarily responsible for coordinating the move
and for repositioning of the head.
 It is recommended to disconnect blood pressure cuffs and
arterial and venous lines that are on the side that rotates
furthest to avoid dislodgment.
 Full monitoring should be reinstituted as rapidly as
possible.
 Endotracheal tube position and adequate ventilation are
reassessed immediately after the move.

Because the abdominal wall is easily displaced, external
pressure on the abdomen may elevate intra- abdominal
pressure in the prone position.
External pressure on the abdomen may push the diaphragm
cephalad, decreasing functional residual capacity and
pulmonary compliance, and increasing peak airway pressure.
Abdominal pressure also may impede venous return through
compression of the inferior vena cava.
As such careful attention must be paid to the ability of the
abdomen to hang free and to move with respiration.
The prone position presents special risks for morbidly
obese patients, whose respiration is already compromised,
and who may be difficult to reposition quickly.

PROBLEM RELATED PRONE POSITION
Airway.
• Accidental extubation.
• Obstruction of ETT bloody secretions/ sputum plugs.
• Facial, Airway edema.
 Visual loss.
 Neck injury.
Excessive lateral torsion or hyperflexion → Post-op pain,
cervical nerve root or vascular compression.
 Accentuation of pre-existing trauma Multiple skeletal
injuries m a y be further exacerbated during positioning

sitting position /beach chair position

The sitting position ( although infrequently used because of
the perception of risk from venous and paradoxical air
embolism, offers advantages to the surgeon in approaching
the posterior cervical spine and the posterior fossa.)
The main advantages of the sitting position over the prone
position for neurosurgical and cervical spine surgeries are;
excellent surgical exposure
decreased blood in the operative field
reduced perioperative blood loss.
superior access to the airway, reduced facial swelling, and
improved ventilation, particularly in obese patients.(to the
anesthesiologist)

The head may be fixed in pins for neurosurgery or taped in
place with adequate support for other surgeries.
Arms must be supported to the point of slight elevation of
the shoulders to avoid traction on the shoulder muscles
and potential stretching of upper extremity neurovascular
structures.
The knees are usually slightly flexed for balance and to
reduce stretching of the sciatic nerve, and the feet are
supported and padded.
Because of the pooling of blood into the lower body under
general anesthesia patients are particularly prone to
hypotensive episodes.
Head and neck position has been associated with
complications during surgery to the posterior spine or skull in
the sitting position.

Excessive cervical flexion has numerous adverse consequences.
 It can impede arterial and venous blood flow, causing hypoperfusion or venous
congestion of the brain.
 It m a y impede normal respiratory excursion.
 Excessive flexion also can obstruct the endotracheal tube and place significant
pressure on the tongue.
Because of the elevation of the surgical field above the heart, and the
inability of the dural venous sinuses to collapse because of their bony
attachments, the risk of venous air embolism is a constant concern.
Arrhythmia, desaturation, pulmonary hypertension, circulatory compromise, or
cardiac arrest m a y occur.

Potential complications from sitting
position.
Venous air emboli.
Hypotension.
Brainstem manipulations resulting in hemodynamic
changes.
Risk of airway obstruction.
Pneumocephalus
Quadriplegia.

►Fowler's position, is typically used for neurosurgery and shoulder surgeries.
► In the standard Fowler’s position, the patient sits upright at an angle between
30 to 90 degrees. The legs of the patient are either bent at the knees or laid out
straight on the bed. When positioning a patient in Fowler's position, the surgical
staff should minimize the degree of the patient's head elevation as much as
possible and always maintain the head in a neutral position. The patient's arms
should be flexed and secured across the body, the buttocks should be padded,
and the knees flexed 30 degrees.
► The position is preferred as an option to combat respiratory distress syndrome
since it
allows for better chest expansion and improves breathing by facilitating oxygen
ation
For patients who are incapable of moving.
.

VARIANTS OF FOWLER’S POSITION
0-30 : low fowler’s position.
30-45 : semi fowler’s position.
45-60 : fowler’s position.
60- 90: high fowler’s position.

Semi-Fowler’s Position.
A semi-Fowler’s position is similar to the standard Fowler’s position, however, the head and back
rest at a lower angle. The bed is typically inclined at an angle of 30 to 45 degrees, although 30
degrees is most frequently used. This position is implemented for a number of medical reasons
including:
•Feeding;
•Lung expansion;
•To decrease cardiac or respiratory conditions;
•After shoulder, nasal, cranial, abdominal and breast reconstruction surgeries;
•For patients with a nasogastric tube.
Semi-Fowler’s is considered the most comfortable position for patients who have a nasogastric
tube fitted, as it ensures the tube remains fixed in its place. Additionally, the semi-Fowler’s
position is also used for pregnancy because it improves the mother’s comfort.
Low-Fowler’s Position.
This position is similar to the supine position, and is considered the best position for rest.
In a low-Fowler’s position, the patient’s head is inclined at a 15- or 30-degree angle. This
position is typically used:
After a procedure;
To reduce lower back pain;
To prevent aspiration during tube feeding.

High-Fowler’s Position
In this position, the patient is upright and the spine is kept straight. The
upper part of the body is angled between 60 to 90 degrees with respect
to the lower portion of the body. While allowing for easy breathing, this
is also considered the best position for:
•Defecating;
•Easy breathing;
•Eating;
•Swallowing;
•Taking x-rays.
•Better surgical exposure;
•Increased drainage of blood and cerebral spinal
fluid;
•Increased homeostasis;
•Improved breathing;
•Relaxed abdominal muscles.
BENEFITS
•A decrease in the return of blood to the heart;
•An increased risk of venous embolism;
•An increase in air or gas inside the skull;
•An increased potential for airway loss, nerve damage,
facial edema, pneumocephalus, and quadriplegia.
•A patient has an increased pressure risk in their
scapulae, sacrum, coccyx, ischium, back of knees,
and heels.
DRAWBACK

Jack - knife position
The patient is either anesthetized supine and turned
prone, or is placed in position before anesthetic is
administered. The hips are on a pillow or towel
directly over the table break and the table is flexed
90º, with the head and legs down.
The patient’s arms are on arm boards with hands
toward the head. The buttocks may be separated by
wide tape placed at the level of the anus on both sides
and secured to the table.
The patient is taken out of the position by first
flattening the table and then reversing the order of
movements into the prone position. Arms are usually
positioned over the head for turning .
Jackknife position, also known as Kraske, is similar
to Knee-Chest positions and is often used
for anorectal and gluteal surgeries.

Physiological changes
 The jack knife position has been described as the most precarious of
surgical positions. Both respiration and circulation can be most
adversely affected. Vital capacity is reduced due to restricted
diaphragmatic movement and increased blood volume in the lungs,
reducing lung compliance.
 There are mixed reports about the cardiac effects of the prone jack knife
position. If the patient is improperly positioned, transmitted pressure
on the vena cava may cause blood pooling in the lower extremities and
result in decreased venous return.
 There was no change in heart rate, mean arterial pressure, and systemic
vascular resistance with change from the supine position to the prone
jack-knife position, but there was a decrease in the left ventricular
stroke work index and a significant increase in the pulmonary capillary
wedge pressure.

 When patients in the sitting positing are considered to
be baseline, there is a 9% decrease in vital capacity in
the supine position, a 12.5% decrease in the jack knife
position, and an 18% decrease in the lithotomy position.
 Overall, the effects of the jack knife position were
comparable to other surgical positions and were
believed to be manageable by experienced
anesthesiologists.

13%
17%
23%
17%
6%
6%
4%
4%
11%
1st Qtr 2nd Qtr 3rd Qtr 4th Qtr 5th Qtr
6th Qtr 7th Qtr 8th QTR 9TH Qtr
NERVE INJURY CLOSED CLAIMS FOLLOWING ALL ANESTHESIA TYPE.
1.ULNAR NERVE INJURY.
2.BRACHIAL PLEXUS INJURY.
3.SPINAL CORD INJURY.
4.LS ROOT INJURY.
5. SCIATIC NERVE DAMAGE.
6. MEDIAN NERVE INJURY.
7.RADIAL NERVE INJURY.
8.FEMORAL NERVE INJURY.
9.OTHER
1990-2010 DATA

ULNAR NERVE INJURY
● most common nerve injury in
anesthetized patient.
● often injuried when compressed
between the posterior aspect of
medial epicondyle of elbow and arm
board or bed.
● more likely with elbow flexed or
forearm pronated.
● symptoms include loss of sensation of
lateral aspect of hand and inability to
abduct or oppose the fifth finger(clow
hand).

BRACHIAL PLXUS INJURY
● second most common type of injury.
● injury occours often when plexus is stretched or
compressed between the clavicle and first rib.
● seen in prone and supine position where head
rotated and laterally flexed to the opposite side
and arm is extended .

PERIOPERATIVE EYE INJURY AND VISUAL LOSS
Most common –corneal abrasion.
Postoperative visual loss.
ischemic optic neuropathy.
central retinal artery occlusion.
RISK FACTOR.
1) prolong hypotension.
2) long duration.
3)anemia and large crystalloid use.
4)increase IOP.

PREVENTION OF
PERIOPERATIVE NEUROPATHY.

Preoperative assesment
 When judged appropriate,it is helpful to
ascertain that patients can comfortably
tolerate the anticipated operative procedure.
 Body habitus,preexisting neurological
symptoms,diabetes, peripheral vascular
disease ,alcohol dependence,arthritis and sex
are the risk factor perioperative neuropathy.

Upper extremity positioning.
 Limit arm abduction to 90 degree in supine position, patient who are
positioned prone may tolerate arm abduction more than 90 degree.
 Arm should be positioned to decrease pressure on the posterior condylar
groove of humerous .when arm are tucked at the side,a neutral forearm
position is recommended.when arm are abducted on armboards either
supination or ,a neutral forearm position is acceptable.
 Flexion of the elbow may increase the risk of ulnar neuropathy ;however
there is no consensus on the degree of acceptable flexion.
 Extension of the elbow beyond a comfortable range may stretch the
median nerve.
 Periodic Perioperative assesment may ensure maintaince of the desired
position.

Lower extremity position
 Lithotomy position that stretch the hamstring muscle group
beyond a comfortable range may stretch the sciatic
nerve.
 Extension of hip and flexion of knee stretches the sciatic
and its branches . Consider the effect of both when
determining the degree of hip flexion.
 Avoid prolong pressure on the peroneal nerve at the
fibular head.
 Neither extension nor flexion of hip that increase the risk of
femoral neuropathy.

Protective padding
 The risk of neuropathy decresed by:
●padded armboards.
●the use of chest roll in laterally positioned patients.
●padding at the elbow.
●padding at the fibular head.
if to tight, however ,padding may increase the risk of
neuropathy.

Equipments
 Properly functioning and positioned automated blood pressure
cuffs on the arms do not affect the risk of upper extremity
neuropathy
 Shoulder braces in steep head down position may increase the
risk of brachial plexus neuropathy.
 Operation table is also required in good and proper condition
and it should be running properly.
 All other periphery object around operation table its deffered
from table surface and should be clean.
 Adequte amount of proper padding material are available.

Postoperative assesment
 A simple postoperative assesment of
extremity nerve function may lead to
early recognition of peripheral
neuropathy.

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