POSTOPERATIVE HYPOXIA
Dr S. Parthasarathy.
MD., DA., DNB., PhD(physiology) FICA,
Dip software based statistics.
CUGRA,IDRA.
Professor , Mahatma Gandhi medical college and research institute – Pondicherry
Associate editor - IJA
WHAT IS HYPOXIA ?
OXYGEN FLUX
• Oxygen flux = CARDIAC OUTPUT × 1.34 × Hb × SATURATION
• Saturation is important
• 90 % IS great
• Definition of hypoxia is
• PaO2 < 60 mmHg -SaO2 < 90 %
WHY WE ARE BOTHERED
• A healthy fellow comes
• We give narcotics
• Anaesthetics
• Agents
• Relaxants
• What is common ---- Hypoxia
INCIDENCE
• Gordh in 1958 and by Nunn and Payne in 1962
• Hypoxia can occur in the postoperative period even if
• Preop CVS and RS are normal
• PaCO2 is normal Probably 30 %
• Normal tidal volumes !! after surgery –
abdominal
Transport
Danger !!
TYPES OF HYPOXIA
• Hypoxic hypoxia
• Anaemic hypoxia
• Stagnant hypoxia
• Cytotoxic hypoxia
WHICH FACTORS DECIDE ??
• Patent airway
• Effective ventilation
• Effective gas interchange
• Arterial oxygen saturation (SaO2) and pressure (PaO2)
• Effective systemic and capillary circulation
• Haemoglobin concentration and integrity
• Effective oxygen release from Hb
• Unhindered extracellular diffusion
• Normal oxygen use by cells.
SEE IT AS AN IMAGE
WHAT FACTORS CAN PRECIPITATE RED
ALERT
• Site of operation – chest Vs upper abdominal Vs lower abdominal – 10 %pao2 less in chest -
subcostal
• Duration of surgery – more than 70 minutes
• Position – kidney position and decreased cardiac output
• Forced expiration against a tube – collapse
• Higher age group
• Bronchospasm – unnoticed – Lap or
• Is there a sigh ? open
WHEN DO YOU NEED TO BE ON RED ALERT !
• Smokers
• Hypothermia
• Fluid overload
• Elderly
• and obesity
• Preop SaO2 < 95 %
WHAT SYMPTOMS AND SIGNS
• Tachypnea,
• Dyspnea
• Irregular breathing
• Tachycardia
• Early hypertension – late hypotension
• Not needed – can be agitation , disorientation
FINK HYPOXIA
• Bernard fink in 1955 –
• When a patient is recovering from N2O anaesthesia, large quantities of this gas cross
from the blood into the alveolus (down its concentration gradient) and so for a short
period of time, the O2 and CO2 in the alveolus are diluted by this gas
• A sufficiently large decrease in the partial pressure of oxygen leads to hypoxia. The
decrease in CO2 pressure can also potentiate this effect when ventilation is suppressed,
leading to potential hypoxemia.
• Occurs only for a few minutes
• Usually corrected with oxygen supplementation
do a few minutes
• Mechanism ??
UPPER AIRWAY
• Tongue fall
• Oro or nasopharyngeal airways
• Laryngospasm
• Laryngeal muscle weakness
• Thyroid surgeries
• Airway edema expected
• Tube trauma
• Anaphylaxis
• Throat packs
AGENTS OR NARCOTICS OR
NM BLOCKERS
Unconscious ?
Not always the agent --- it can be respiratory depression and CO2 narcosis
Pinpoint pupils
TOF ?
BRONCHOSPASM
• Pharyngeal and tracheal stimulation from secretions, aspiration, or suctioning can trigger
constriction of bronchial smooth muscle.
• Neostigmine
• Disinfectant spray
• Anaphylaxis
• Latest wheezing attack Breathing type wheezing
• Thoracoabdominal surgeries and desaturation
• inhalation Prophylaxis decreases
What precipitates ?
INCOMPLETE REVERSAL FROM
NEUROMUSCULAR AGENTS – SETTINGS ?
• Electrolyte disturbances
• Hypothermia
• Myopathies
• Drugs like magnesium
• Organ dysfunction
• Dosage
• Recurarization
ATELECTASIS
• Atelectasis refers to a partial collapse of the small airways. The majority of post-operative
patients will develop some degree of atelectasis, resulting in abnormal alterations in lung
function or compromise to the lung’s immune defences.
• Obesity, abdominal surgeries
• WHY ??
• combination of airway compression , reduction of FRC
• alveolar gas resorption intra-operatively,
• impairment of surfactant production.
ATELECTASIS
• Within 24 hours
• Cough dyspnea
• Fever ??
Xray chest PA
• Can go up to weeks HPV dampened by
agents
• PEEP – intraop
• Chest physiotherapy Endo bronchial
• Pain relief intubation
• Bronchoscopy
• CPAP
• Shift the case in head up position
PNEUMOTHORAX
• Hypotension and hypoxia
• Decreased breathing one side
Central venous
• Xray chest
cannulation
• USG chest
Supraclavicular
brachial plexus
• OXYGEN high FIO2
• ICD SOS
Any bulla in CxR
• Clinical scenarios ??
PNEUMONIA
• Chest pain
• Cough fever
• Chills Main determinants for pneumonia after
• Dyspnea surgery were hypertension, chronic renal
failure,
extubation after 6h
reintubation.
• May go for hypotension !!
• Expect when ??
CULTURE AND ANTIBIOTICS WITH
PHYSIO
Cough and deep-breathing exercises with incentive spirometer.
Twice daily oral hygiene with chlorhexidine swabs.
Ambulation with good pain control.
Head-of-bed elevation to at least 30° and sitting up for all meals.
Can use filters in selected cases
PNEUMONIA AND COLLAPSE
ARDS------LEAVE ALONE CARDIAC
VASCULAR MAJOR SURGERIES
• Any surgery --
• Higher ASA physical status,
• emergent surgery,
• chronic obstructive lung disease, Aspiration !!
• increased intraoperative airway pressures, TRALI
• high fraction of inspired oxygen,
• aggressive fluid and transfusion therapies
• When to think otherwise ?
• Type 1 respiratory failure !!
• Hypoxia but no hypercarbia
PULMONARY EDEMA
• Myocardial infarct
• Anaphylaxis ECG, CxR, USG,
• Negative pressure ECHO
• Neurogenic
• Fluid overload Oxygen,. Diuretics
and NIV
PULMONARY EMBOLISM
• Tachycardia
• Tachypnoea • ECG
• Signs of DVT
• Low grade fever • ECHO ?
• New onset arrhythmia
• CT angiography ?
• Abrupt or slower
• Supportive with heparin / thrombolysis
24 – 48 hours • Long term heparin
later
CIRCULATORY AND ANEMIC
• Causes of decreased cardiac output- intra op causes
• Anemic hypoxia - CO Hb
• Hypothermia can shift the curve to left
• All types of hypoxia are worsened by shivering !
TIMING !!- IMMEDIATE, JUST DELAYED OR DELAYED
• Come out of drugs !! Agents , narcotics and Nondepolarizers
• Fink , Spasm and stridor
Immediate
• Bronchospasm
• Pneumothorax
Just delayed
• TRALI , aspiration ARDS
• Atelectasis, pneumonia, pulmonary edema
Delayed
APPROACH
• Give oxygen
• Check pulse oximeter and the patient
• Conscious status
• Airway spasm and obstruction
• Breathing pattern
• Pulse and blood pressure
• Anaemia and pallor
• Definition
• Incidence
• Causes
• Timing
• Expect when and what ?
• Shivering
• Pulse oximeter doubts
ANESTHESIA – SLIDES IN
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