Transcript Monitoring and Management of the Patient in the ICU

Chapter 46
Monitoring the Patient in the
Intensive Care Unit
Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.
Learning Objectives
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Discuss the principles of monitoring the
respiratory system, cardiovascular system,
neurological status, renal function, liver function,
and nutritional status of patients in intensive
care.
Discuss the risks and benefits of intensive care
unit (ICU) monitoring techniques.
Discuss why the caregiver is the most important
monitor in the ICU.
Describe how to evaluate measures of patient
oxygenation in the ICU.
Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.
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Learning Objectives (cont.)
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Define why Paco2 is the single best index of ventilation for
critically ill patients.
Describe the approach used to evaluate changes in
respiratory rate, tidal volume, minute ventilation, Paco2,
and end-tidal Pco2 values for monitoring purposes.
Discuss monitoring techniques used in the ICU to evaluate
lung and chest wall mechanics and work of breathing.
Discuss the importance of monitoring peak and plateau
pressures in patients receiving mechanical ventilatory
support.
Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.
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Learning Objectives (cont.)
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Introduce monitoring techniques that have
become available recently such as stress,
strain, FRC, stress index, Electrical
Impedance Tomography and Acoustic
Respiratory Monitoring.
Describe the approach used to interpret the
results of ventilator graphics monitoring.
Describe the cardiovascular monitoring
techniques used in the care of critically ill
patients and how to interpret the results of
hemodynamic monitoring.
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Learning Objectives (cont.)
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Discuss the importance of neurological status
monitoring in the ICU and the variables that
should be monitored.
Discuss evaluation of renal function, liver
function, and nutritional status in intensive care.
Describe and discuss the use of composite and
global scores to measure patient status in the
ICU, such as the Murray lung injury score and
the APACHE severity of illness scoring system.
Discuss monitoring and troubleshooting of the
patientventilator system in the ICU.
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Introduction to Monitoring
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Continuous monitoring or periodic checks
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Gray area between diagnostic and monitoring
procedures
• Risk/benefit ratio
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Monitored Values
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All data must be evaluated in context of overall
clinical presentation
Instrument inaccuracyrecalibrate
Artifacts
Factitious events: true but temporary (cough)
Treat pathology, not errant number
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All values monitored must be considered in relation to
what pathology has altered them and how best to
treat the pathology
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Respiratory Monitoring
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Gas Exchange
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Arterial Blood Gas
• pH
• PaCO2
• PaO2
• Calculated HCO2
• Estimated base excess or deficit
• SaO2
Oxygenation
Ventilation
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Monitoring
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Monitoring Oxygenation
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Tissue oxygenation depends on CaO2 (PaO2
and SaO2), cardiac output, and oxygen
uptake
Pulse oximetry (“fifth vital sign”)
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Provides noninvasive measurement of SaO2,
referred to as SpO2
Monitors only oxygen, not ventilation
Significant limitations
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All of the following are true about pulse oximetry
monitoring, except:
A.
B.
C.
D.
Provides an SpO2 reading
Provides invasive measurement of SaO2
Monitors only oxygen, not ventilation
Significant limitations
Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.
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Monitoring Oxygenation (cont.)
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All of the following values affect pulse oximetry,
except:
A.
B.
C.
D.
Nail polish
Deeply pigmented skin
Anemia
CO2 buildup
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Other Oxygen Indices
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Oxygen consumption
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Difficult to measure, so seldom used
Normal 250 ml/min, 25% of oxygen delivery
P(A  a)O2
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Healthy patient
• 21% O2, gradient is 5 to 15 mm Hg
• 100% O2, gradient is 100 to 150 mm Hg
Abnormal increase associated with gas exchange
problems
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Other Oxygen Indices (cont.)
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PaO2/FIO2 ratio (P/F ratio)
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Normal P/F ratio is 400 to 500.
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In Acute Lung Injury - ALI, this falls below 300.
In Acute Respiratory Distress Syndrome - ARDS, will
be < 200.
Most reliable index of gas exchange if FIO2 > 0.50 and
PaO2 < 100 mm Hg
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QS/QT (physiologic shunt)
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Increased if pulmonary venous admixture occurs
(mixed venous blood exits A/C membrane unchanged)
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Which of the following PaO2/FIO2 ratio identifies
a patient with ARDS?
A.
B.
C.
D.
500-600
300-500
>200
<200
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Monitoring Ventilation
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Routine monitoring includes
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PaCO2, which defines adequacy of ventilation
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 VT, f, and V
VE
• Low VT and high f often indicate distress
 VD/VT
• Normal 0.20 to 0.40
• Higher ratio indicates more wasted ventilation
• ICU common to be > 0.60
• >0.60, patient is unlikely to sustain spontaneous ventilation
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Monitoring Ventilation (cont.)
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Inspired vs. Expired Tidal Volume
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Normal Inspired – (VTI) and expired tidal volume
(VTE) should be nearly equal.
• Air leak will result in higher VTI than VTE.
Capnography
Capnometry
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Monitoring Ventilation (cont.)
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All of the following are true regarding VD/VT
ratio, except:
A.
B.
C.
D.
Normal 0.40 to 0.60
Higher ratio indicates more wasted ventilation
ICU common to be >0.60
If >0.60, patient is unlikely to sustain
spontaneous ventilation
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Compliance
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Compliance is ΔV/ΔP or effective VT/(Pplat  PEEP) .
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Normally, is 60 to 100 ml/cm H2O
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In severe ARDS, may be <25-30 ml/cm H2O
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Many pulmonary diseases alter compliance
• See Box 46-7.
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Resistance
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Resistance (Raw) = (PIP  Pplat)/flow
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Normally 1 to 2 cm H2O/L/sec
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Intubated, typically 5 to 10 cm H2O/L/sec or more
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See Box 46-7 for diseases that alter Raw
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Auto-PEEP
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If exhalation is incomplete, intrinsic or autoPEEP occurs
Causes ⇑FRC and mean alveolar pressure
Often causes patientventilator asynchrony
Ways to decrease auto-PEEP
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Decrease VE
 Increase ET
 Decrease IT
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Auto-PEEP (cont.)
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Adding extrinsic PEEP may overcome the
trigger sensitivity issue and facilitate lung
emptying
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Slowly increase in 1-2 cm H2O increments until
either:
• Patient can trigger the ventilator
• Auto-PEEP increases
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Measuring Auto-PEEP
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Presence noted by expiratory flow at end of
expiration
Measured by
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End-expiratory hold: most common method
• Allows alveolar pressure to equalize with ventilator
pressure.
 Esophageal balloon
 Increase PEEP until end-expiratory flow is zero
• PEEP applied estimates auto-PEEP
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Auto-PEEP can be measured by all of the
following, except:
A.
B.
C.
D.
Esophageal balloon
Inspiratory pause
Increase PEEP until end-expiratory flow is zero
End expiratory hold
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Monitoring Breathing Effort
& Pattern
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P0.1 assesses ventilator drive
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Occlusion pressure 100 ms after initiation of
inspiration
<6 cm H2O is indicative of patient’s ability to wean
from MV
RSBI (f/VT)
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Respiratory muscle fatigue tends toward rapid
shallow breathing
 RSBI < 105 indicates patient likely to wean from
MV
•
The lower the RSBI the better
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Monitoring Breathing Effort
& Pattern (cont.)
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Vital capacity (VC)
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Effort dependent
VC less than 10 to 15 ml/kg, need for MV
Maximal inspiratory pressure (MIP)
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Not effort dependent, as prolonged occlusion of
airway stimulates maximal effort
 More negative is better
• 20 to 30 cm H2O acceptable
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MIP
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Work of Breathing
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Monitoring During
Lung Protective Ventilation
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Commonly used for ALI/ARDS patients to avoid
ventilator-induced lung injury (VILI)
Three principles confirmed
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Limit Pplat to < 28 cm H2O
 Reduce VT to 4–8 ml/kg
 Use adequate PEEP to avoid opening/closing injury
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Permissive hypercapnia is often used as a lung
protective strategy avoid VILI
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Cardiac & Cardiovascular Monitoring
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Arterial blood pressure
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Invasive or noninvasive
Central venous pressure (CVP)
Pulmonary arterial catheter: high risk-to-return
ratio, so only used on most complicated patients
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Allows monitoring of
• Cardiac output/cardiac index
• Pulmonary arterial pressure
• Pulmonary capillary wedge pressure
• Pulmonary vascular resistance
• Systemic vascular resistance
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Cardiac & Cardiovascular Monitoring
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Cardiac & Cardiovascular Monitoring
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Pulmonary arterial catheter allows monitoring of
all of the following, except:
A.
B.
C.
D.
Cardiac output/cardiac index
Pulmonary and Systemic vascular resistance
Peripheral vascular wedge pressure
Pulmonary arterial pressure
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Hemodynamic Monitoring
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Complete hemodynamic profile from PA
catheter eases determination of cause for
altered hemodynamic status
Table 46-4 shows expected changes in
hemodynamic values associated with clinical
presentation of cardiac or cardiovascular
dysfunction
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Neurologic Monitoring
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Neurologic dysfunction is difficult to recognize in
sedated patient
Obtain history, from family if not from patient
Neurologic examination
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Mental status
 Pupillary response and eye movement
 Corneal and gag reflex
 Respiratory rate and pattern
 ICP monitoring (10 to 15 mm Hg normal)
 Glasgow Coma Scale (see Table 46-6)
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Monitoring Renal Function
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Kidney functions
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Filtering and excretion of wastes
Regulates fluid and electrolyte composition
Renal failure is noted by
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BUN increases of 10 to 15 mg/dl/day
Creatinine increases of 1 to 2.5 mg/dl/day
Urine volume reflects renal perfusion
• Oliguria <400 ml/day in average-sized adult
• Anuria occurs with <50 ml/day
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Monitoring Nutritional Status
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Adequate nutrition key for healing
Assessment for malnutrition important
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Including organ function and muscle wasting
Serum albumin concentration most common
• <2.2 g/dl reflects severe malnutrition; shows chronic, not
acute, change
• Also altered by sepsis, dehydration, trauma
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Estimating Nutritional Needs
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First step is estimating caloric need
Estimate the basal energy expenditure, or BEE
Harris-Bennedict equation estimates BEE
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Men = 66 + (13.7) (wt) + 5 (ht) – 6.8 (age)
Women = 65 + (9.6) (wt) + 1.8 (ht) – 4.7 (age)
For ill patients, often multiply the result by a stress
factor of 0.5 to 2.5.
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