Intraoperative Hypotension

1
Intraoperative Hypotension

• John A. Mattoni, M.D.
• SFGH

2
Intraoperative Hypotension

• Case 39 yo female hairdresser with stab wounds
  to anterior abdomen X5
• Vital signs stable in ED 113/73 86 18 100
• GCS 12 (E4,M6,V2)
• Hct 22, ABG 7.37/33/278, -6
• CXR Right hemothorax
• PMH - unknown

3
Intraoperative Hypotension

• Preoperative
• Chest tube placed on right in ED (400cc out)
• 2units PRBC transfused in ED
• Abdominal ultrasound fluid in RUQ
• Pt remained stable. Observed in PACU 1hr while
  2 other trauma cases finished (husband)

4
Intraoperative Hypotension

• Operative
• Monitors standard, foley, radial arterial line
• Access bilateral 14 ga IV in place
• Induction Rapid Sequence with STP/SUX
• Pt remained stable after induction/intubation
• 130s/80s, 90s , 100

5
Intraoperative Hypotension

• Operative (cont.)
• Soon after incision, BP dropped to 90/40 with
  pulse 120s.
• Liver laceration to left lobe noted, actively
  bleeding
• Stab wound to stomach X2

6
Intraoperative Hypotension

• Hypotension - Differential Diagnosis
• 1. Inadequate inflow to heart
• 2. Decreased pump function
• 3. Decreased vascular resistance

7
Intraoperative Hypotension

• Inadequate inflow to heart
• 1. Many Causes
• most common inadequate intravascular volume
• blood loss, third spacing, evap loss, fever, NG
  suction, resp losses
• relative hypovolemia venous pooling, positional
  changes, surgical packs or traction
• 2. Diagnosis
• urine output, tachycardia, CVP, PCWP

8
Intraoperative Hypotension

• Decreased Cardiac function
• Myocardial depressant drugs volatile
  anesthetics, B-blockers, CA channel blockers,
  propofol, barbiturates, lidocaine
• Arrhythmias
• Myocardial ischemia or infarct
• Hypocalcemia (rare)

9
Intraoperative Hypotension

• Decreased Vascular Resistance
• Sympathetic blockade
• Neurogenic
• Drug effects
• Sepsis
• Anaphylaxis

10
Intraoperative Hypotension

• Operative (cont.)
• Pt received 2u PRBC quickly
• BP responded to 110s/50, P110, 100
• However, initial (pre incision) ABG
  7.30/30/496, -8, Hct 34

11
Intraoperative Hypotension

• Operative (cont.)
• 30 min later, BP drops to 80/40, P125, 100
• Post transfusion ABG (5 min before above )
  7.25/33/498,-12.8, Hct36
• No response to volume (crystalloid, PRBC) and
  minimal response to phenylephrine or ephedrine

12
Intraoperative Hypotension

• Operative (cont.)
• Surgeon reports some fluid had been seen in
  pericardial sac
• Anterior thoracotomy performed near parasternal
  stab wound
• Pericardium lacerated, heart normal, minimal
  fluid in sac
• CaCl given without response

13
Intraoperative Hypotension

• Operative (cont.)
• Phone call from daughter into OR
• She has a
• LATEX ALLERGY

14
Intraoperative Hypotension

• Operative (cont.)
• Epinephrine infusion started
• Benadryl 50mg given
• Hydrocortisone given
• Pts vital signs remained stable throughout the
  rest of the OR course
• Repeat ABG 7.34/33/353,-8, Hct 29

15
Latex Allergy

• What is meant by latex allergy?
• The allergy is an IgE mediated reaction to the
  soluble proteins or processing chemicals used to
  produce latex products
• Allergies to latex can be along the continuum
  from contact dermatitis to localized or
  generalized reactions, including anaphylaxis

16
Latex Allergy

• High-Risk Groups
• 1. Pts with multiple surgical procedures
• myelomeningocoele, congenital GU tract anomalies
• spina bifida incidence 30-70
• 2. Health Care Personnel - up to 17
• 3. Other Occupational Exposure
• hair dressers, greenhouse workers, latex
  manufact.
• 4. Hx of hay fever, rhinitis, asthma or eczema
• 5. Food Allergy to tropical fruits, chestnuts,
  stone fruits

17
Latex Allergy

• Three types of reactions in latex allergy
• 1. Irritant contact dermatitis
• 2. Type IV hypersensitivity
• - skin rxn similar to poison ivy
• 3. Type I hypersensitivity
• - from hives and erythema to anaphylaxis and
  cardiovascular collapse

18
Latex Allergy

• Chemistry of Latex
• Natural Rubber Latex (NRL) is a complex mixture
  of polyisoprene, lipids, phospholipids and
  proteins
• Many chemical added (preservatives, accelerators,
  antioxidants, vulcanizing)
• Protein content responsible for majority of
  allergic rxns to latex (over 240 proteins)

19
Latex Allergy

• Irritant Contact Dermatitis
• most freq rxn to latex
• direct action of latex and other chemicals
• not mediated by immune system, not a true allergy
• deterioration in skin integrity enhances
  absorption of latex protein allergens and is
  believed to accelerate onset of allergic rxns

20
Latex Allergy

• Type IV Delayed Hypersensitivity
• also called contact dermatitis or delayed
  hypersensitivity
• skin rxn like poison ivy
• appears 6-72 hrs after initial contact
• most anaphylactoid reactions are Type IV
• cell mediated depend on antigen reactive cells
  (rather than antibodies)

21
Latex Allergy

• Type IV Delayed Hypersensitivity
• mild dermatitis to skin blisters
• 84 of immunologic responses to gloves are Type
  IV
• Not all Type IV progress to Type I
• 79 of Type I pts had Type IV symptoms

22
Latex Allergy

• Type I Immediate Hypersensitivity
• Also called IgE mediated anaphylactic rxn
• Requires prior sensitization
• Reactions usu within minutes of exposure
• Symptoms from mild to life-threatening

23
Latex Allergy

• Type I Immediate Hypersensitivity
• Antigen induces production of an antibody of the
  IgE class. Re-exposure to antigen causes
  degranulation of mast cells and basophils through
  cross linking, which triggers a cascade of
  events, including release of histamine,
  arachidonic acid, leukotrienes and
  prostaglandins.

24
Latex Allergy

• Management of Latex-Sensitive Patients
• 1. Coordination of care between anesthesia,
  surgical, nursing, and other support teams to
  remove latex exposure
• 2. First Case of the day - aerosolized latex
  antigen lowest level in OR suite
• 3. Signs signifying Latex Allergy posted
• 4. Latex-free cart should accompany patient

25
Latex Allergy

• Management of Latex-Sensitive Patients
• 5. Medical alert bracelet should be obtained
• 6. Pharmacological prophylaxis
• controversial
• included diphenhydramine, H2 blockers, and
  steroids
• leaves anaphylaxis as the first evidence of
  allergic rxn
• not universally successful in preventing latex
  anaphylaxis

26
Latex Allergy

• Management of Latex Sensitive Patients
• 7. Medications should not be drawn up or
  administered through rubber caps or diaphragms
  and should not remain in contact with the rubber
  in the syringe plunger for long periods of time
• 8. Wash hands to remove any traces of powder or
  latex

27
Latex Allergy

• Treatment of An Allergic Reaction to Latex
• Contact Dermatitis and Type IV reactions can
  usually be treated with avoidance and topical
  corticosteroids
• Treatment of a systemic reaction to latex same as
  for other systemic allergic reactions
• mild reactions (hay fever) - respond to
  antihistamine
• hives - antihistamines and systemic steroids
• anaphylaxis - formal treatment protocol

28
Latex Allergy

• Acute Management
• 1. Call for help, notify surgical and OR staff
  of possible latex reaction
• 2. Remove all latex from surgical field
• 3. Change gloves to non-latex
• 4. Discontinue all antibiotic and blood admin.
  (to rule out other forms of allergic rxns)
• 5. Maintain airway (intubate as indicated) and
  administer 100 O2

29
Latex Allergy

• Acute Management (cont.)
• 6. Infuse 25-50 ml/kg of crystalloid or colloid
  as indicated
• 7. Administer epinephrine
• IV 0.1 mcg/kg (10 mcg in adult)
• SQ 300mcg (0.3mg)
• Endotracheal 5-10 times IV dose (50-100mcg)
• 8. Consult allergist, draw levels of mast cell
  tryptase, complement C3/C4, and histamine

30
Latex Allergy

• Secondary Therapy
• 1. Antihistamine (controversial)
  Diphenhydramine 1mg/kg IV or IM (50mg max dose)
  Ranitidine 1mg/kg IV (max dose 50 mg)
• 2. Glucocorticoids Hydrocortisone 5mg/kg
  initially, then 2.5mg/kg q 4-6 hrs.
  Methylprednisolone 1mg/kg initially and 0.8 m/kg
  q 4-6 hours
• 3. Aminophylline for bronchospasm load 5mg/kg,
  then 0.4 - 0.9 mg/kg/hr

31
Latex Allergy

• Secondary Therapy (cont.)
• 4. Inhaled Beta 2 agonist for bronchospasm
• 5. Continuous catecholamine infusion for BP
  support
• Epinephrine 0.02-0.05 mcg/kg/min (2-4 mcg/min)
• Norepinephrine 0.05 mcg/kg/min (2-4 mcg/min)
• Dopamine 5-20 mcg/kg/min