Anesthetic Complications in the Surgical Patient

Slide 1

Anesthetic Complications in the Surgical Patient

A clinical review of mortality, morbidity, airway, and cardiovascular risk in operative anesthesia.

Presented at the Karl Heusner Memorial Hospital, Belize City, Belize, C.A.

Slideshow by Dr. Nerida De Paz · published by H. De Paz, MD, FACS.

This lecture was written and delivered by my dearest sister. I publish it as her swan song. — Hec

Slide 2

ANESTHETIC MORTALITY

  • Death only if it occurred within a specific time interval after anesthesia
    • 24 hrs — Harrison 1978
    • 48 hrs — Turnbull 1980
  • Time interval is arbitrary
  • Classification facilitates data collection

Slide 3

ANESTHETIC MORBIDITY

  • Unplanned, unwanted and undesirable consequence of anesthesia
    • Causing permanent disability
    • Serious distress and/or prolongation of hospital stay but no permanent sequelae
    • Minor morbidity causing only minor distress but no sequelae

Slide 4

CAUSES OF ANESTHETIC MORTALITY

  • Airway problems
    • Esophageal intubation
    • Difficult intubation after paralysis
    • Failure to maintain airway
    • Laryngeal spasm
    • Aspiration of gastric contents

Slide 5

ANESTHETIC MORTALITY

  • Pre-existing diseases
  • In most deaths, surgical, anesthetic and patient factors are involved
  • Death due to anesthesia is rare
  • ASA 5 patients have no chance of surviving anesthesia
  • ASA 1 patients have no increased risk of mortality from anesthesia alone

Slide 6

AMERICAN SOCIETY OF ANESTHESIA (ASA) PHYSICAL SCORING SYSTEM

  • ASA 1 — no pre-existing disease
  • ASA 2 — pre-existing disease, stable
  • ASA 3 — pre-existing disease, unstable
  • ASA 4 — critical
  • ASA 5 — moribund

Slide 7

ANESTHETIC MORTALITY RISK

  • Emergencies 35× more likely to die than elective
  • Anesthetic-related deaths also occur in healthy individuals
  • 1–2 per 10,000 deaths are unexplicable

Slide 8

ANESTHETIC ISSUES

  • Did the anesthesiologist make an error?
  • Was the death the result of an unexpected reaction to an anesthetic drug?
  • Was there failure of equipment?

Slide 9

Human error

  • Use of 100% N₂O instead of 100% O₂
  • IM suxamethonium instead of ketalar
  • IV Na citrate instead of KCl
  • IV adrenaline instead of atropine
  • Wrong concentration of lidocaine during CPR

Slide 10

High-risk patients · cardiovascular

  • Avoidable risk in CV diseases
  • Myocardial O₂ imbalance (ischemic heart disease)
  • Cardiac failure (CF)
  • Arrhythmias

Slide 11

MONITORING OF ISCHEMIA

  • Heart rate
    • Tachycardia is the hemodynamic abnormality that signifies adverse outcome with IHD
  • Hemoglobin
    • Hb > 10 g/dl is required before anesthesia/surgery
  • Pulse oximetry & BP
  • EKG
    • Standard test for detecting heart abnormality and evaluating anesthetic outcome
  • ECHO

Slide 12

OXYGEN SUPPLY & DEMAND

  • Determinants of myocardial oxygen demand
    • Heart rate & contractility
  • Oxygen delivery
    • CO × CaO₂
    • CO = SV × HR
    • CaO₂ = (1.34 × Hb × SaO₂) + (0.003 × PaO₂)
    • SaO₂ = arterial O₂ saturation
    • 1 g of Hb binds 1.34 ml O₂ when fully saturated
    • NB: Hb in g/dl; Hb-bound O₂ as ml/dl

Slide 13

Predictors

  • ST changes indicate ischemic episodes associated with increased incidence of periop infarction
  • Recent MI with CF — most important predictor of periop cardiac morbidity

Slide 14

HIGH-RISK PATIENTS

  • Myocardial O₂ imbalance
    • Ischemic heart disease
    • Congestive heart failure
    • CHF is a poor outcome determinant and should be treated prior to surgery
  • Decrease in supply
    • Cardiodepressant effects of anesthetic agents

Slide 15

HIGH-RISK PATIENTS

  • Pre-op arrhythmias
    • Functional significance
    • Tachycardia
    • Hypotension
    • Prognostic significance
    • Significant arrhythmias produce little initial hemodynamic upset but severe abnormal functioning in the periop period

Slide 16

CARDIOVASCULAR DISEASES AND SAFETY OF ANESTHESIA

  • MI
    • Surgery Recent MI and concurrent cardiac failure are the most important predictors of perioperative cardiac morbidity.

Slide 19

POSTOP HYPOXEMIA

  • Cyanosis
  • Restlessness

Slide 20

COMPLICATIONS OF FLUID THERAPY

  • Fluid overload
  • Fluid deficit
    • Dehydration
    • Excessive bleeding
  • Metabolic complications
    • Hypo/hyperglycemia
    • Hypo/hypernatremia
    • Hypo/hyperkalemia
    • Hypo/hypercalcemia

Slide 21

Causes of early hypoxia

  • Obesity
  • Age
  • Smoking
  • Cardiorespiratory diseases

Slide 22

Causes of late hypoxia

  • Chest infection
  • Aspiration
  • Atelectasis
  • Pneumothorax
  • Fat embolism
  • Pulmonary embolism
  • Amniotic fluid embolism

Slide 23

Upper airway obstruction

  • Laryngeal spasm
  • Trauma
    • Oral
    • Teeth, gum, tongue
    • Oropharynx
    • Uvula, pharynx
    • Esophagus
    • Larynx
    • Trachea
    • Tracheomalacia, goitres, tumors
    • Hematoma especially after thyroid surgery

Slide 24

Other conditions causing upper airway obstruction

  • Difficult laryngoscopy
    • Edema
    • Infections
    • Retropharyngeal abscess, Ludwig’s angina, diphtheria
  • Tumors
  • Micrognathia
  • Macroglossia

Slide 25

OTHER AIRWAY HAZARDS

  • Total intubation failure
    • Laryngeal mask airway
    • Fiberoptic laryngoscopy

Slide 26

COMPLICATIONS OF INTUBATION

  • Dislocation of arytenoid cartilage
  • Over-inflation of cuff
  • Use of excessive force
  • Rupture of esophagus
  • Esophageal intubation

Slide 27

X-ray of neck

[Figure: lateral cervical-spine x-ray to be added]

Pre-anesthetic airway assessment: reduced atlanto-occipital extension, prevertebral soft-tissue swelling, and cervical kyphosis all predict difficult laryngoscopy.

Slide 28

Skull x-ray

[Figure: skull x-ray to be added]

Slide 29

Asthma

  • Deeper anesthesia is indicated to block vagal reflexes triggered by instrumentation of the airway
  • Curare and morphine should be avoided
  • Ketamine is drug of choice

Slide 30

Severe liver disease

  • Pre-op coagulation profile mandatory
  • Vit K may be indicated
  • FFP and fresh blood indicated if profile abnormal

Originally published on SurgicalInSite. Slideshow presentation by N. De Paz, MD.