post operative management including pain control and ICU

Postoperative pain management 

Relief of surgical pain with minimal side effect is a primary goal in PACU care In addition to improve patient comfort, relief of pain reduces sympathetic NS (SNS) response & helps control postop hypertension & tachycardia Carefully assessed prior to giving analgesics . Eliminating pain can also precipitate hypoventilation & hypoxemia by accentuating the depressant effects of previously administered opioids. Methods of providing postoperative pain relief Drug treatment Opioid Non-steriodal ant-inflammatory drugs Paracetamol & combinations Regional anesthetic techniques : Central neuraxial blocks (spinal & epidural) Peripheral nerve blocks Local infiltration . Psycological methods Relaxation Hypnosis Psychoprophylaxis .

The Intensive Care Unit (ICU)

The intensive care unit is the hospital facility within which the highest levels of continuous patient care & treatment are provided.Who should be admitted :The cost of providing ICU services is very high & the resources are finiteICU care must be directed toward patients who are most likely to benefitIt is equally important to identify patient who are not ill enough & those who will die despite ICU treatment .Indication of ICU admissionPatient requiring or likely to requiring advanced respiratory support.Patient requiring support of two or more organ systems.Patient with co-morbidity who require support for an acute reversible failure of another organ system.Advanced Respiratory Support Mechanical ventilatory or non – invasive ventilationThe possibility of sudden deterioration in respiratory function requiring immediate tracheal intubation & mechanical ventilation

Basic respiratory support

The need for an inspired oxygen concentration of more than 40% .The possibility of progressive deterioration to the point of needing advanced respiratory support .The need for physiotherapy to clear secretions at least 2 hourly .Patient in whom the tracheal tube has been removed recently after a prolong period of intubation & mechanical ventilation .The need for mask CPAP or non – invasive ventilation .Patient whose trachea intubated to protect the airway but do not need mechanical ventilation.Circulatory support The need for vasoactive drugs .Support for circulatory instability caused by hypovolaemia for any cause unresponsive to modest volume replacement .Patient resuscitated after cardiac arrest where ICU or HDU care is considered clinically appropriate .

Indications for mechanical ventilation

The main indication for mechanical ventilation is : Respiratory failure . Other clinical indications include : a prolonged postoperative recovery . Altered conscious level , Inability to protect the air way . Exhausion when the patient is likely to proceed to respiratory failure . Control of intracranial pressure in head injury . Airway protection following drug overdose . Following cardiac arrest . For recovery after prolonged major surgery or trauma . The aim of mechanical / artificial ventilation is : Is to improve gas exchange . To reduce the work of breathing . To avoid complications while maintaining optimal conditions for recovery .

Respiratory failure

This is primary indication for respiratory support . Pulmonary gas exchange is sufficiently impaired to cause hypoxaemia with or without hypercarbia . The causes of respiratory failure : Inadequate gas exchange Pneumonia Pulmonary oedema Acute respiratory distress syndrom (ARDS) Inadequate breathing Chest wall problems eg fractured ribs , flial chest Pleural wall problems eg pneumothorax ,haemothorax Respiratory muscle failure eg myasthenia gravis, poliomyelitis, tetanus CNS depression eg drugs, brain stem compression Obstructed breathing Upper airway obstruction eg epiglottitis, croup, oedema, tumor . Lower airway obstruction eg bronchospasim .

Types of mechanical ventilation

The most commonly used type of artificial ventilation is intermittent positive pressure ventilation (IPPV).The lungs are intermittently inflated by positive pressure generated by a ventilator. & gas flow is delivered through an endotracheal or tracheostomy or mask ?Tracheal intubation is usually achieved by the oral route although nasal intubation may be better tolerated by the patient during prolonged ventilation .Tracheal intubation :Allows institution of IPPV .Reduces dead space Facilitates airway suctioning .It is also possible to deliver positive pressure ventilation to cooperate patient in non-invasive manner through a tight – fitting face or nasal mask (NIPPV).


Two main types of ventilators commonly in use in ICU
Those that deliver a preset tidal volume .And those that deliver a preset inspiratory pressure during each inspiration .Modern ventilators allow different modes of ventilation & the clinician must select the safest & most appropriate mode of ventilation for the patient .Types of ventilation volume- cycled ventilationOccurs when the ventilator delivers a preset tidal volume regardless of the pressure generatedThe lung compliance (stiffness) of the lungs determines the airway pressure generatedSo this pressure may be high if the lungs are stiff, with the resultant risk of barotrauma (rupture of alveoli resulting in pneumothorax & mediastinal emphysema).Pressure – preset ventilationThe ventilator delivers a preset target pressure to the airway during inspiration The resulting tidal volume delivered is therefore determined by the lung compliance & the airway resistance

Modes of ventilation

Controlled Mechanical Ventilation (CMV)Ventilation with CMV is determined entirely by machine settings including the airway pressure , tidal volume, resoiratory rate , & I : E ratioThis mode of ventilation is not often used in ICU as it does not allow any synchronisation with the patients own breathing As a consequence CMV is not well toleratedPatient require heavy sedation or NM – blockade to stop them (fighting) the ventilator, thereby resulting in inefficient gas exchngeCMV is normally used in theatre when the patient is receiving a full general anesthetic to optimise surgical conditionAssisted Mechanical ventilation (AMV)There are several different modes of ventilation designed to work with the patients own respiratory effortThe patients inspiratory effort is detected & triggers the ventilator to boost the inspiratory breath These modes have two impotant advantages:They are better tolerated by the patientThey allow the patient to perform muscular work throughout the breath, therby reducing the likelihood of developing respiratory muscular atrophyThe ventilator – assisted breaths can be supported either by a preset inspiratory pressure or by a preset tidal volume

There are several variations of assisted ventilation

Intermittent Mandatory ventilation (IMV) is a combination of spontaneous & mandatory ventilation.Between the mandatory controlled breaths , the patient can breath spontaneously & unassisted.IMV ensures a minimum minute ventilation, but there will be variations in tidal volume between the mandatory breaths & the unassisted breathsSynchronised Intermittent Mandatory ventilation (SIMV)With SIMV , the mandatory breaths are synochronised with the patients own inspiratoy effort which is more comfortable for the patient Pressure- support ventilation (PSV) or assisted spontaneous breaths (ASB)A preset pressure – assisted breath is triggered by the patient own inspiratory effort This is one of the most comfortable forms of ventilationThe preset pressure level determines the level of respiratory support & can be reduced during weaningThere are no mandatory breaths delivered , & the ventilation relies on the patient making some respiratory effort.No back up ventilation, should the patient become apnoeic, unless this mode is combined with SIMV

Positive End Expiratory pressure (PEEP)

Is used with all forms of IPPVA positive pressure is maintained during expiration expanding underventilated lung, & preventing collapse of the distal airways.This results in improved arterial oxygenation.However , PEEP causes a rise in intrathoracic pressure & can reduce venous return & so precipitate hypotension , particularly in hypovolaemic patients.With low levels of PEEP (5-10 cmH2O), these effects are usually correctable by IV volume loading.Continuous Positive Airway Pressure (CPAP)Is effectively the same as PEEP, but in spontaneously breathing patients.Criteria for starting mechanical ventilationResoiratory rate >35 or < 5 breaths/min .Exhaustion , with laboured pattern of breathing ,Hypoxia ,central cyanosis , SaO2<90% on oxygen or PaO2<8 kpa.Hypercarbia – PaCO2> 8 kpa.Decreasing conscious level .Significant chest trauma .Tidal volume < 5ml/kg or vital capacity < 15 ml/kg

Initiation Mechanical ventilation

Optimizing oxygenationWhen settling a patient on the ventilator, it is good practice to initially set FiO2 at 1.0 & then wean rapidly to a FiO2 adequate to maintain SaO2 of >93%.FiO2 of greater than 0.6 for long peroids should be avoided if possible because the risk of oxygen – induced lung damage .Strategies to improve oxygenation (other than to increase FiO2) include:Increasing the mean airway pressure by either raising the PEEP to 10 cmH2O Or ,by increasing the peak inspiratory pressure .Avoiding very high inflating pressure (above 35cmH2O) as this may cause barotrauma to the lung .More complex strategies to improve oxygenation may be required in severely hypoxic patient eg. ARDS or acute lung injury from a variety of causes.In sever hypoxia , it may be possible to improve oxygenation by increasing the PEEP further to 15 cmH2O(or above) & using small (6-8ml/kg) tidal volume more frequentlyAnother strategy is to prolong the inspiratory time . Normal inspiratory to expiratory ratio 1:2 but oxygenation may be improved if this ratio is changed to 1:1 or even 2:1In sevsre ARDS the patient can be repositioned & ventilated in prone positionRe-expanding collapsed alveoli & improving the distribution of blood perfusion in the lung relative to ventilation .

Weaning from mechanical ventilation

Weaning is the process by which the patients dependence on mechanical ventilation is gradually reduced to the point where spontaneous breathing sufficient to meet metabolic needs may be sustained. Because of the adverse effect of mechanical ventilation, weaning should be undertaken at the earliest opportunity. Criteria for weaning Clear consciousness with adequate gag & cough reflex . Cardiovascular stability. Stable metabolic state Adequate pulmonary function . Tidal volume > 5 ml/kg . Vital capacity > 10 ml/kg. SaO2 > 90% on oxygen 40% or PaO2 > 10 kpa PaO2 < 6 kpa