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Surgical Intensive CareJUNYI LI, MD
Board certified in AnesthesiologyBoard certified in Critical Care MedicineBoard certified in Transesophageal Echocardiography
March 31, 2009
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Subspecialty ICU
• Medical Intensive Care Unit (MICU)• Coronary Care Unit (CCU)• Surgical Intensive Care Unit (SICU)• Neurological Intensive Care Unit (NICU)• Cardiovascular Intensive Care Unit (CVICU)• Pediatric Intensive Care Unit (PICU)• Neonatal Intensive Care Unit (NICU)
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SICU Admission Criteria• Preoperative status Major trauma Surgical Procedure Pt’s preexisting disease• Intraoperative event Large volume shift Unexpected surgical complication Unexpected anesthesia complication• Postoperative status Unexpected postop complication Pt’s status
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Who need to be admitted to SICU ?• 18 y/o health male presented for right inguinal hernia repair
under spinal anesthesia and uneventful intraop and postop.• 50 y/o female with controlled HTN and DM for lumbar
laminectomy under general anesthesia with EBL 500 ml.• 75 y/o male with stable angina, COPD required home oxygen
for TURP under spinal anesthesia• 60 y/o male presented for AAA repair• 54 y/o female with esophageal cancer presented for
esophagectomy • 95 y/o female presented for right hip arthroplasty
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SICU Management• Respiratory care • Hemodynamic monitoring and management Noninvasive Invasive• Infection in SICU• Acid-base disorders• Fluid and electrolyte disorders• Blood component therapy• Nutrition support
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Respiratory care – basic monitor
• Respiratory rate• Chest movement• Breath sound• Color
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Respiratory care – lung volume
• Tidal volume (VT)• Minute ventilation (Vm)• Functional residual capacity (FRC)• Vital capacity (VC)
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Respiratory care - ventilation
• Ventilation-perfusion (V/Q) ratio: normal V/Q=4L/5L=0.8
• Dead space ventilation: V/Q>1 anatomic dead space & physiologic dead space
• Intrapulmonary shunt: V/Q<0.8 true shunt (V/Q=0) and venous admixture
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V/Q relationship and associated blood gas
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Effect of shunt fraction on PAO2
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Effect of shunt fraction on PAO2 and PACO2
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Ventilation-perfusionQuantitative determinations
• Dead space (Vd/Vt) = (PACO2 – PECO2)/PACO2
• Shunt fraction (Qs/Qt) = (CCO2 – CAO2)/(CCO2 –CVO2)
• A-a gradient (PAO2 – PaO2) PAO2 = PIO2 – (Paco2/RQ) PAO2 = FIO2(PB –PH2O) – (PaCO2/RQ) PAO2 = 0.21(760 – 47) – (40 /0.8) = 100 mmHg
• PAO2/FIO2<200, Qs/Qt>20% PAO2/FIO2>200, Qs/Qt<20%
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Hypoxemia
Disorder A-a PO2 PVO2
Hypoventilation Normal Normal Pulmonary disorder Increased Normal DO2/VO2 imbalance Increased Decreased
DO2/VO2 – oxygen deliver and uptake ratio A-a PO2 – PO2 difference between alveolar gas and arterial blood PVO2 – Mixed venous PO2
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Evaluation of hypoxemia
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Hypercapnia
• Hypercapnia is PACO2>45 mm Hg, due to • Increased CO2 production• Hypoventilation• Increased dead space ventilation
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Evaluation of hypercapnia
High
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Oximetry
• Oximetry detects arterial blood HbO2 and Hb ratio
• Ear oximetry• Pulse oximetry• Co-Oximeters can detect Met Hb and CO Hb• Mixed venous oximetry measured O2 sat in PA
blood
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CO2 detector and capnometry• CO2 detector is a method for determining the
success or failure of ET intubation.• Clinical application of capnometry in ICU: - Cardiac output monitor - Ventilator-related mishap detection - Early detection of nosocomial disorders - Ventilator weaning - Controlled hyperventilation
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Acute respiratory distress syndrome (ARDS)
• A leading cause of acute respiratory failure with high mortality
• A diffuse inflammatory injury in the lung• Not an accumulation of watery edema fluid• Not a primary disease, but a complication
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Common conditions that predispose to ARDS
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ARDS microscopic changes and CXR
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Diagnostic criteria for ALI and ARDS
• Acute onset• Presence of predisposing condition• PaO2/FiO2 < 200 mm Hg for ARDS,
< 300 mm Hg for ALI• CXR – bilateral infiltrates• PAOP < 18 mm Hg or no clinical evidence of
high LA pressure
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Management of ARDS
• No real treatment for ARDS, only supportive• Mechanical ventilation:
low-volume ventilation permissive hypercapnia positive end-expiratory pressure
• Fluid management – reducing extravascular lung water
• Pharmacotherapy – uncertain effect
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Respiratory therapy
• Oxygen inhalation therapy• Chest physical therapy• Respiratory pharmacotherapy• Mechanical ventilation
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Oxygen inhalation therapy
• Arterial hypoxemia: PaO2 < 60 mm Hg (SaO2 < 90 %)
• Tissue hypoxia: blood lactate > 4 mmHg
• Endpoint of O2 therapy is tissue oxygenation• Tissue hypoxia may not consistent with
arterial hypoxemia
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Effect of Oxygen on blood flow
• Oxygen tends to reduce systemic blood flow due to: 1. vasoconstrction in all vascular bed except
the pulmonary circulation 2. decrease in cardiac output 3. negative inotropic effect
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Method of oxygen inhalation
• Low-flow oxygen delivery system with variable FiO2
• High-flow oxygen delivery system with constant FiO2
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Device Reservoir Oxygen flow FiO2 capacity (L/min) Nasal cannula 50 ml 1 0.21-0.24 2 0.24-0.28 3 0.28-0.34 4 0.34-0.38 5 0.38-0.42 6 0.42-0.46Oxygen face mask 150-250 ml 5-10 0.40-0.60Mask-reservoir bag 750-1250 ml Partial rebreather 5-7 0.35-0.75 Nonrebreather 5-10 0.40-1.0
Low-flow oxygen delivery systems
FiO2 = 20 + 4 X oxygen flow (L/ml)
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Respiratory pharmacotherapy
• Bronchodilators
• Corticosteroids
• Mucokinetic therapy
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Mechanical Ventilation
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Mechanical ventilation
• Mechanical ventilation is positive pressure ventilation
• Indications of mechanical ventilation Rate ABG: hypoxia and hypercapnia Mechanical parameter: MV, VC and NIP Dead space and shunt
• Contraindication of mechanical ventilation
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Normal lung Noncompliant lung
Effect of positive pressure ventilation
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Effect of positive pressure ventilation
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Respiratory parameter
• Rate: 10 – 20/min• VT: 6 – 10/kg• FiO2: 40 – 100%• PEEP: 5 – 10 cm H2O• PS: 5 – 10 cm H2O• I:E ratio: 1:2
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Patterns of mechanical ventilation
• Control mode ventilation
• Assist-control ventilation
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Pattern of mechanical ventilation
• Volume-controlled ventilation ACV (assist control ventilation) IMV (intermittent mandatory ventilation) SIMV (synchronized IMV)
• Pressure-controlled ventilation• Pressure support ventilation• Special pattern:
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Functional mode of ventilator
• PEEP (positive end expiratory pressure)
• PS (pressure support)
• I:E reversal ratio
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Ventilatory mode of mechanical ventilation
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Volume-controlled ventilation
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Pressure-controlled & Pressure support
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PEEP and CPAP
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Effect of PEEP on arterial oxygenation and CI
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Discontinuing mechanical ventilation
• Ventilator required for brainstem respiratory depression (e.g.,GA in OR or drug overdose) is easy to discontinue
• Ventilator required for cardiopulmonary insufficiency is weaning in gradual process
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Discontinuing mechanical ventilation
Clinical evaluation: Awake Spontaneous breathing Ability of airway protection Stable hemodynamics
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Discontinuing mechanical ventilation
Sequence of weaning: FiO2 to 50% or less PEEP to 5 cm H2O or less PS to 10 cm H2O or less
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Discontinuing mechanical ventilation Bedside weaning parameters:Parameter Normal range Threshold for weaningPaO2/FiO2 >400 200 VT 5-7 ml/kg 5 ml/kg Rate 10-20/min <40/min VC 65-75 ml/kg 10 ml/kg VE 5-7 L/min <10 L/min
Pi max >-90 cm H2O (F) -24 cm H2O >-120 cm H2O (M) Rate/VT <50/min/L <100/min/L
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Predictive value of selected weaning parameters
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Discontinuing mechanical ventilation
Methods of weaning: T-piece weaning IMV weaning CPAP weaning
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Diagram of T-shaped circuit
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Hemodynamic monitoring Noninvasive
• ECG: heart rate, rhythm, ischemia (ST-T)• Noninvasive BP• Echocardiography: TTE, TEE, color-doppler Contractility Volume status EF Ischemia (RWMA) • Noninvasive cardiac output (through A-line)
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Hemodynamic monitoringInvasive
• Arterial blood pressure• Central venous pressure• Pulmonary artery catheter and wedge pressure• Cardiac output
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Invasive arterial blood pressure
• Major CV surgery• Surgery with great hemodynamic change• Surgery with large volume shift and bleeding• Shock and other critical ill patients• Surgery requiring hemodilution and control
hypotension• Frequent ABG
Indication
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Invasive arterial blood pressure
• Contraindication: only relative contraindication except for puncture site infection
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Invasive arterial blood pressureSelection of artery for cannulation
• Radial artery• Ulnar artery• Brachial artery• Femoral artery• Dorsalis pedis and posterior tibial arteries• Axillary artery• Carotid artery – do not use
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Invasive arterial blood pressureComplication
• Bleeding and hematoma• Vasospam• Thrombosis and thrombi• Aneurysm• Infection• Nerve damage• Necrosis of skin overlying the catheter
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Invasive arterial blood pressureWaveform
SBP gradually increasesMBP remains unchanged
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Invasive arterial blood pressure Waveform distortion
Normal test
underdamped
overdamped
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Central venous pressureIndication
• Fluid administration for severe hypovolemia and shock
• Infusion of cardiac drugs• Aspiration of air emboli in craniotomy• Insertion of transcutaneous pacing leads• Total parenteral nutrition (TPN)• Venous access for patients with poor
peripheral veins
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Central venous pressureContraindication
• Renal cell Ca extension into RA, RA myxoma, or fungating tricuspid valve vegetations
• Skin infection at cannulation site• Severe coagulopathy • Ipsilateral carotid endarterectomy (IJ),
pneumothorax and hemothorax are relative contraindication
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Central venous pressureSelective sites of cannulation
• Internal jugular veins• Subclavian veins• Femoral veins• External veins• Basilic veins
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Central venous pressureMeasurement
• Catheter’s tip lies above or the junction of SVC and RA
• CVP is measured with cm H2O• CVP should be measured during end expiration
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Central venous pressureWaveform
• a wave – atrial contraction, absent in A fib and exaggearted in JR (cannon wave)
• c wave – TV elevation@early ventricular contraction• v wave – venous return against to closed TV• x descent – downward displacement of TV (systole)• y descent – TV opening during diastole
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Central venous pressureComplication
• Bleeding and hemotoma• Pneumothorax and hemothorax• Pleural effusion and chylothorax• Line-related infection• Air thrombi
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Pulmonary artery catheterization
Length 110 cmOD 2.3 mmDistal portProximal portBalloon at tipThemistor
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“It Is Time To Pull The PAC”
PAC dose not improve outcome in critically ill patients
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Background• Pulmonary artery catheter(PAC) has been used in
critical care practice for three decades• Majority of PAC are inserted to aid in
management of critically ill pts in ICU and high risk surgical pts in OR
• Observational studies & small randomized controlled trials (RCT) showed variable results:
Worse outcome No difference in outcome Some benefit
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Summary
• PAC-directed management in high risk surgical, severe sepsis, shock and RADS pts is a safe procedure
• PAC use dose not improve outcome• PAC use may not increase cost of care
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Pulmonary artery catheterizationIndication
• Cardiac disease: CAD with LV dysfunction, valvular heart disease, heart failure
• Pulmonary disease: ARDS, severe COPD, Pulmonary hypertension
• Complex fluid management: shock, acute burn ARF, MOF
• Specific surgical procedure: aortic cross clamp pheochromocytoma, liver transplants,
• Hemodynamic unstability required cardiovascular drug therapy
• High-risk obstetrics: severe toxemia
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Pulmonary artery catheterizationContraindication
• Severe TV or PV stenosis• RA or RV tumor• Endocarditis with vegetation on TV or PV• Other contraindication related to central
venous cannulation
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Pulmonary artery catheter
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Pulmonary artery catheterization Insertion of catheter
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PCWP and CVP
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Pulmonary artery catheter in chest x-ray
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Pulmonary artery catheterizationComplication
• Complication associated with CV cannulation• Bacteremia and endocarditis• Thrombogenesis and pulmonary infarction• Pulmonary artery rupture and hemorrhage• Arrhythmias and conduction abnormalities• Pulmonary valve damage
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Pulmonary capillary wedge pressure
CVP = RAP = RVEDPPCWP = LAP = LVEDP
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Hemodynamic parameter
• BSA = (Ht + Wt – 60)/100, nl 1.6 to 1.9 m2• CO = HR x SV• CI = CO/BSA• DO2 = CI x 13.4 x Hb x SaO2
• VO2 = CI x 13.4 x Hb x (SaO2 – SvO2) * SvO2 obtained from PAC distal port
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Hemodynamic Profiles
• Heart failure: Right heart failure Left heart failure High RAP High PCWP Low CI Low CI High PVRI High SVRI
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Hemodynamic profiles
• Hypotension: Hypovolemic Cardiogenic Vasogenic Low CVP High CVP Low CVP Low CI Low CI High CI High SVRI High SVRI Low SVRI
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Cardiac output monitoring
• Thermodilution methods Pulmonary artery catheter Peripheral artery catheter (Picco)
• Dye dilution methods• Echocardiography• Thoracic bioimpedance
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Cardiac output monitoring Fick principle
CO = Oxygen consumptiona – v O2 content difference
= VO2
CaO2 – CvO2
Fick principle is the basis of all indicatordilution methods of determining cardiac output
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Thermodilution method
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Hemodynamic management
• Preload• Afterload• Cardiac contractility
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Hemodynamic managementPreload
• Monitoring via CVP or PCWP• Increased preload by giving volume• Decreased preload by giving diuretics and/or
vasodilators (nitroglycerin)
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Hemodynamic managementAfterload
• Vascular resistance• Balance between cardiac work and organ perfusion • Vasodilators: Systemic vasodilators: nitroprusside, calcium channel blockers, a1-blockers Pulmonary vasodilators: PGE1, PGI, NO• Vasocontrictors: levophed, epinephrine, vasopresin
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Hemodynamic managementInotropic agents
• Positive inotropic agents: epinephrine, dopamine, dobutamine, PDEI (milrinone)
• Negative inotropic agents: beta blocker and calcium channel blockers
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Hemodynamic managementMechanical support (IABP)
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Hemodynamic effect of IABP
• Decrease afterload and promote SV• Increased diastolic pressure and coronary
blood flow in hypotensive patients• Indication: AMI, cardiac shock, unstable
angina, acute MR• Contraindication: AI, aortic dissection and
aortic graft in thoracic aorta• Complication: leg ischemia, septicemia
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Acute renal failure (ARF)• The hallmark of ARF is azotemia and oliguria• Lab: blood urea nitrogen(BUN), criatinine(Cr), blood
electrolytes, glumerular filtration rate• Etiology: prerenal, renal and postrenal Renal ischemia (50%), Nephrotoxines (35%), Intrinsic renal disease (15%) 50% of ARF in SICU due to major trauma or surgery
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Etiology of ARF
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Treatment of ARF
• Supportive management• Diuretics and mannitol to maintain urine
output in nonoliguric patients• Renal dose dopamine?• Glucocorticoids for ARF due to vasculitis or
glomerulonephritis• Other: restrict fluid, sodium, potassium, posph• Renal replacement therapy (dialysis)
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Renal Replacement Therapy
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Infection in SICU
• Infections are leading cause of death in ICUs• Community acquired and hospital acquired infection • Strains of bacteria resistant to commonly used
antibiotics are common• Advanced age, prolonged use of invasive devices,
respiratory failure, renal failure and head trauma are established risk factors for hospital acquired infection
• Multiple antibiotics and broad spectrum antibiotics are commonly used in SICU
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Nutrition support in SICU
• Maintaining adequate nutrition in critically ill patients improves wound healing. Restore immune competence and reduces morbidity and mortality
• Critically ill patients generally required 1.0-1.5g/kg/day instead of 0.5g/kg/day for nonstressed patients
• Enteral nutrition and parenteral nutrition
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Enteral Nutrition in SICU
• GI tract is the route of choice for nutrition support when its functional integrity is intact
• Enteral nutrition is simpler, cheaper, less complicated, and fewer complication
• Enteral nutrition can better preserve GI structure and function
• Diarrhea is most common problem related to hyperosmolarity of the solution or lactose intolerance
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Parenteral Nutrition in SICU
• Total parenteral nutrition (TPN) is indicated if the GI tract cannot be used of if absorption is inadequate
• Complications of TPN are catheter-related and metabolic
• The most common problem in TPN is hyperglycermia