physiological changes in various position.pptx

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

2. 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.

3. 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.

4. 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 pulmonary vasculature.

5. SUPINE

6. 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.

7. 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

8. 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

9. 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

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

11. 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

12. 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 posit ioning.

13. • 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

14. • 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.

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

16. 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 .

17. 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

18. 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.

19. • 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.

20. 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.

21. * Trendelenburg position * * Reverse Trendelenburg position* AND

22. • 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.)

23. • 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

24. 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 may 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 when 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.

25. 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

26. 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.

27. 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 mass is present (tumor, gravid uterus), abdominal pressure may 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.

28. Problem related to lithotomy position Common peroneal nerve injury.(most common)branch of sciatic nerve. Femoral nerve injury. Oburator nerve injury. 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

29. 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.

30. Position

31. Lateral decubitus position

32. 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.

33. 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.

34. 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.

35. T he 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.

36. PRONE POSITION

37. 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 may 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 may be supported face- down with its weight borne by the bony structures or turned to the side.

38. Both arms may be positioned to the patient’s sides and 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 and active compression devices are needed for the lower extremities to minimize pooling of the blood, especially with any 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 when 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.

39. ●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.

40. 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.

41. PROBLEM RELATED PRONE POSITION A i rway. 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 may be further exacerbated during positioning

42. sitting position /beach chair position

43. 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)

44. 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.

45. Excessive cervical flexion has numerous adverse consequences . It can impede arterial and venous blood flow, causing hypoperfusion or venous congestion of the brain. It may 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 may occur .

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

47. Fowler’s position

48. ► Fowler's position, is typically used for neurosurgery and shoulder surgeries. ► I n 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 oxygenation For patients who are incapable of moving . .

49. 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.

50. 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.

51. 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

52. 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  ano rectal and gluteal surgeries.

53. 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 .

54. 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.

55. COMMON SIDE EFFECTS

56. 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

57. 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).

58. 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 .

59. 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.

60. PREVENTION OF PERIOPERATIVE NEUROPATHY.

61. 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.

62. 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.

63. 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.

64. 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.

65. 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.

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

67. Thank you