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1. ANESTHESIA FOR ACUTE
INTESTINAL OBSTRUCTION

2. DEFINITION
 A mechanical/functional blockage arising
from a structural abnormality that presents a
physical barrier to the progression of gut
contents.

3. TYPES
 Partial or complete
 Simple or strangulated
 Acute or Chronic
 Dynamic or Adynamic

4.  On the basis of origin :
1) Extraluminal (e.g. Adhesions, Hernias or
carcinomatosis.)
2) Intraluminal (e.g. Gallstones or Foreign
bodies.)
3) Intramural (e.g. Crohns disease or tumors.)

5. 1. Dynamic (Mechanical) –
Peristalsis is working against a mechanical
obstruction.
2. Adynamic –
- Atony of the intestine.
- Loss of normal peristalsis.
- Absence of a mechanical cause.

6.  MC cause :
Small bowel obstruction –
Postoperative adhesions.
Large bowel obstructions –
Neoplasms.

7. • Small bowel obstruction (60%-80%)> Large
bowel obstruction.
• Large bowel obstruction more insidious.
• Systemic derangements less severe with
large bowel obstruction.

8. Preoperative Management
1. Fluid and Electrolyte Imbalance
2. Bowel and Abdominal Distention
3. Respiratory Problem
4. CVS Problem

9. 4. Vomiting, Regurgitation and Aspiration.
5. Investigation
6. Premedication

10. 1. Fluid and Electrolyte Imbalance
 Dehydration:
 Normally 7-9L fluid  secreted into upper
intestinal tract daily.
 Because of small intestinal reabsorption,
only 400 ml passes ileocecal valve.

11.  In small intestinal obstruction, fluid loss
occurs due to:
 Increased secretion
 Decreased reabsorption
 Accumulation of fluids.

12.  As intraluminal pressure  Secretory
function of bowel increases.
 Pressure above 20 cm H2O  Reabsorption
is impaired.

13.  This causes loss of isotonic salt water
resulting in isotonic contraction of ECF
volume.
 Dehydration and increased hematocrit occur.

14. 1. Fluid and Electrolyte Imbalance
6000ml of fluid accumulation in bowel.
At late stages with hypotension and tachycardia
3000ml of fluid accumulation in bowel.
At Well established cases with vomiting
1500ml of fluid accumulation in bowel.
At Early stage

15. 1. Fluid and Electrolyte Imbalance
 The degree of dehydration is evaluated by:
1. Duration of illness
2. Presence of vomiting
3. Skin elasticity
4. Sunken eye
5. Oliguria

16.  The degree of ECF loss can be monitored by
serial hematocrit determinations
 Rise in Hct is proportional to the amount
of fluid loss.
 If Hct increases to 55% this indicates that
about 40% of plasma and ECF volume
have been lost.

17.  Treatment :
 Primary goal :
1) Initial restoration of intra-vascular
volume to the state of normovolemia.
2) Correction of electrolyte disturbances
and acid base derangements.

18.  Lactated ringers solution is
appropriate to use for resuscitation.
 Guide to fluid replacement –
1) CVP
2) Hourly urine output
3) BP
4) Heart rate.
5) Skin turgor

19. I. Fluid and Electrolyte Imbalance
 Electrolyte Disturbances:
1. Hyponatremia and Hypochloremia.
 Because fluid accumulation and vomiting.
2. Hypokalemia.
 Mainly due to renal mechanisms.
 Secondary to metabolic alkalosis and
hyperaldosteronism.

20.  Acid Base Imbalance:
 Metabolic Acidosis are more common
due to:
 Dehydration and loss of alkaline
intestinal secretion.
 Starvation ketosis.

21. II. Bowel and Abdominal Distention
 Occurs due to accumulation of fluids and
gases.
 Resulting in:
a. Blockade of the venous outflow.
b. Blockade of the blood supply to the
obstructed segment.
c. Hindering of diaphragmatic movement.

22. d. Decreasing venous return.
e. Progressive distension may cause rupture
of colon.
f. Progressive distension may cause tense
abdominal wall.

23. II. Bowel and Abdominal Distention
Management ::
1. Naso-gastric tube for abdominal
decompression in preoperative management.
2. Deeper anaesthesia and muscle relaxants to
provide adequate operative conditions.

24. 3. Gradual escape of fluid  Monitor BP frequently
during incision. (sudden escape of fluids into the
peritoneal cavity may cause severe hypotension).

25. Role of nasogastric aspiration
1. Reduce bowel distension
2. Improve pulmonary ventilation
3. Reduce risk of subsequent aspiration during
induction of anesthesia and post extubation

26. III.Respiratory Problems
 Due to:
1. Abdominal distension which hinders the
diaphragm resulting in inadequate ventilation.
 This decreases ( TV, FRC) and causes a
decrease in PaO2 and an increase in PaCO2.
2. Weakness of intercostal muscles due to
hypokalemia.

27. IV.CVS Problem
 Hypotenion and Tachycardia up to shock.
 Due to:
1. Hypovolemia
2. Decreased VR.
3. Septic shock
4. Hyponatremia

28.  Arrhythmias (ventricular).
 Due to:
1. Hypokalemia

29. V. Vomiting, Regurgitation and
Aspiration.
 Reversal of peristalsis and mechanical
obstruction pushes the intestinal juice in
addition to the gastric juice to produce a full
stomach with an increased inta-abdominal
pressure.

30. VI.Investigation
1. X-ray abdomen in supine and erect
position:
 To ensure diagnosis of intestinal
obstruction.

31. 2. To detect complications:
 Hct.
 WBCs
 Electrolytes, Acid base disturbances.
 Arterial blood gas.

32. VII.Premedication
 Avoid all oral premedication.
 Avoid drugs that may inhibit respiration.
e.g. opioids, sedative.

33.  Avoid anticholinergics e.g. If fever or
tachycardia occur.
 Avoid antiacids or H2 blockers although
there is a risk of aspiration as;
 They may stimulate vomiting.
 They are of low value if a large volume of
fluids are already sequestrated in the
bowel e.g. High intestinal obstruction.

34. Intraoperative Management
1. Choice of anesthesia.
2. Monitoring.
3. Induction and Intubation.
4. Maintenance.
5. Extubation.

35. Intraoperative management
 Choice of anesthesia
 Regional anesthesia :
avoided if significant fluid depletion is
suspected.
 General anesthesia : Should be the
method of choice.
 Monitoring:
 Standard and CVP.

36. Intraoperative management
 Induction and Intubation:
 There is a major risk of aspiration causing
very high mortality rates.
1. Awake Intubation:
 In cooperative patient.

37. Intraoperative management
2. Rapid sequence induction:
 Its done in supine or lateral position with
head down tilt (10 degree) to avoid
aspiration if vomiting occurs.
 Preoxygenation: 8-10L OF 100% O2 for
2-5 min.

38.  Precurarization (defasciculation) doses of
NDMR to avoid suxamethonium
fasciculation.

39.  Naso-gastric tube should be removed
before intubation to:
 Allow effective cricoid pressure.
 Avoid lower esophageal sphincter
dysfunction.
 Avoid hindering of laryngoscopy and
intubation.

40. Intraoperative management
 Iv agents:
1. Thiopentone is a good choice if there is NO
hypotension.
2. Ketamin or Etomidate are good choice if
there is hypotension.

41. Intraoperative management
 Maintenance :
 O2 + Potent inhalational agent + NDMR +
IPPV
 Careful titration of doses of inhalation agents is
needed to avoid severe hypotension.
 N2O should be avoided in bowel obstruction
because it increases gas distension which
increases intra-luminal gas volume and
pressure.

42. This results in:
1. More increased abdominal distension
2. Increased bowel ischemia and necrosis.
3. Difficulties with abdominal closure at the
end of surgery.

43.  Administration of high concentration
of inspired oxygen  reduced
incidence of surgical wound
infections.
 Timely use of antibiotics.
 Maintenance of normothermia.

44. Intraoperative management
 Extubation:
 Awake extubation in left lateral position.
• After returning of upper airway reflexes
• After good suctioning.

45. Postoperative management
 Continue the preoperative management
 Fluid and electrolyte correction.
 Respiratory and CVS monitoring.

46.  Postoperative ileus
 Due to hyponatremia and hypokalemia.
 Postoperative abdominal decompression
 Continued for 5-6 days

47. Postoperative management
 Postoperative respiratory problems
 Abdominal distension is present
 Abdominal pain is present
 Residual effects of inhaled and IV
anaesthetic.
 15-20% reduction of FRC more than a
week after any upper abdominal surgery.

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