Anesthesiology Clinics of North America
Volume 15 • Number 4 • December 1997
Copyright © 1997 W. B. Saunders Company
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Critical Care Medicine in Transition: The
Anesthesiologist's Role
DATA COLLECTION AND ANALYSIS IN THE ICU
Charles G. Durbin, Jr, MD
From the Surgical Intensive Care Unit, University of Virginia Health Sciences Center,
Charlottesville, Virginia
Address reprint requests to
C.G. Durbin, Jr, MD
Department of Anesthesiology
Box 10010
University of Virginia HCS
Charlottesville, VA 22906
ISSUES IMPORTANT TO CRITICAL CARE MEDICINE
Two important factors have influenced the development of critical care units: Patients
require rapid, specific interventions to prevent physiologic deterioration or death, and
hospitals need to effectively and efficiently provide necessary levels of service. The first
issue is patient and disease driven; the second is economic and practical.
Anesthesiologists have been important contributors to the advancement of critical care
because the profession has successfully addressed the same issues in operating rooms
(OR) and postanesthesia care units.
Among the many attributes of an anesthesiologist, two skills are especially significant for
outstanding clinical practice--(1) the ability to lead a team of professionals
inconspicuously and (2) the ability to analyze massive amounts of data efficiently and act
rapidly on the results. Those are the unique strengths that ensure anesthesiologists a role
in the future of critical care medicine (CCM). Major differences between OR and
intensive care unit (ICU) practice discourage many anesthesiologists from beginning or
continuing practice in the ICU. Long-term patient care issues; inadequate experience with
nutritional support, infectious disease, and specific organ therapies; and a lower rate of
payment for services have contributed to the lesser interest among anesthesiologists in
pursuing careers in CCM. As the balance of financial incentives and career opportunities
shifts from the OR toward
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the ICU, the number of anesthesiologists regularly caring for the critically ill will
increase.
This article describes the breadth and types of data sources that are encountered in the
critical care environment. Some are identical to those observed in the OR and some are
unique to the ICU. Mastery of all the areas is not essential for every critical care
practitioner, but, understanding the sources of data and how they impact on various
decision makers will improve the effectiveness of anyone working in CCM. Changes in
the routes of health care delivery will have a major impact on the ICU. Specific sources
of information to be considered are physiologic data and monitoring, laboratory data,
outcomes information and prediction systems, critical care research, and quality and cost
information. This discussion is not meant to be exhaustive but to give the reader an
introduction to those important areas. Similarities with OR practice are emphasized. The
belief is that anesthesiologists are particularly qualified by personality, training, and
experience to integrate multiple data sources and make appropriate decisions in the ICU.
In that way, they can uniquely contribute to the continued growth and development of
CCM and ensure the persistence of anesthesiology's influence in that vital area. The role
of the perioperative physician will include providing care to patients in ICUs,
understanding how care is integrated in the ICU, and prudently managing expensive
resources.
PHYSIOLOGIC DATA AND MONITORING
As is the case in the OR, CCM practitioners are bombarded with a huge number of
physical and physiologic measurements. Some of them are used as patient or equipment
monitors; others are used for diagnosis. In many cases, the same measurement device is
used for both monitoring and diagnosis. The distinction between data being used for
monitoring and for diagnosis is often blurred. Confusion regarding use of the same device
for monitoring and diagnosis has led to inappropriate risk-benefit analysis of particular
monitors. Several years ago, Robin [38] called for a ban on the use of the Swan-Ganz
catheter because it has never been shown to improve outcome in critically ill patients.
Insertion of a pulmonary artery catheter is associated with significant risks, including the
possibility of pulmonary artery rupture and death. The extreme position taken by Robin
demonstrates a basic misunderstanding of the function of monitors and how effectiveness
of monitoring can be assessed.
The use of monitors is routine in the OR. "To monitor" means "to observe closely," and a
"monitor" is an "advisor, informant, or counselor." Monitors are not active devices; they
do not directly provide patient care; they can only advise or inform. In evaluating the
effect of monitors on patient care, it is important to remember that fact. Monitoring is
only the first step in initiation of action. The clinician selecting and using the monitor is
the essential ingredient in quality patient care. Errors in the use of monitors can occur
because of inadequate education,
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inexperience, or inattention by the caregiver. Those sources of problems can result in an
undesired patient outcome despite appropriate monitor selection and function.
Figure 1 illustrates the process of acquiring data and performing an action in an ICU. The
output from a monitor suggests that further testing is needed to confirm a specific
diagnosis. After the results are acquired, a diagnosis is established and an action may be
taken. For example: A ventilator monitor indicates a low exhaled minute volume
(monitor output). The breathing circuit is examined (additional test) and a partial
disconnection at the endotracheal tube is identified (diagnosis). The circuit is reconnected
to the patient (action) and now the exhaled minute volume monitor shows a normal value
(monitoring output). If a caregiver had not noticed (or heard) the monitor, had not found
the disconnection, or had not reconnected the patient, harm might have occurred. In
evaluating the impact or value of a particular monitor, it is important to recognize the
additional steps necessary to affect patient outcome. A monitoring device is no better
than the person using it.
ALARMS AS MONITORS
In life-threatening situations, additional diagnostic or confirmatory tests sometimes are
bypassed and action is taken without a firm diagnosis,
Figure 1. The output of a monitor often triggers additional tests before an action is taken.
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as illustrated in Figure 2 . When a particular event is believed to cause an undesired or
lethal outcome, action should be empirical, without delaying to more firmly establish the
cause (diagnosis). Alarms are a special case of monitoring related to that type of situation.
When the parameter being monitored falls outside of the safe range, a visual or auditory
"alarm" is issued by the monitoring device. Once again, no change in patient treatment is
instituted by the monitoring device; a caregiver must make the decision to act. Caregivers
often have control over the limits that trigger the monitor alarm.
Given the total system, it is not reasonable to expect that monitors, by themselves, will
impact patient care in a positive way. Any time a monitor is evaluated for its impact on
patient care, the action scheme discussed here must be taken into account. Because
invasive monitors always involve direct patient risks, they can easily be shown to
increase morbidity. It is more difficult (if not impossible) to show they improve patient
outcome because it is the caregiver using the device who has the major impact on
outcome.
Several monitors reflecting different, but related, aspects of patient physiology often are
used concurrently, and often is difficult to identify the most important monitor in a given
situation. Furthermore, an experienced, watchful clinician can often respond
appropriately to a critical situation without use of complicated monitors. This further
confuses the objective analysis of the impact of specific monitors on patient care.
Besides aiding the caregiver in deciding to initiate active interventions, monitors reduce
caregivers' anxiety by confirming that the functions being monitored are proceeding
appropriately. That allows attention to be directed to other areas or other patients.
Monitors are extensions of the caregiver's senses. More than one variable can be watched
simultaneously. In a busy ICU, unlike the usual OR, one caregiver often manages two or
more patients. Monitors help accomplish that task efficiently. Table 1 lists some of the
many purposes for using monitors.
The reduction in uncertainty provided by monitoring has affected the frequency of
medical malpractice actions. The widespread use of
Figure 2. Alarms are a special case of monitoring in which an action may take place before a specific
diagnosis is made.
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TABLE 1 -- PURPOSES OF MONITORING IN INTENSIVE CARE UNIT PATIENTS
1. Reduce uncertainty
a. Reduce caregiver anxiety
b. Reduce medico-legal risk
c. Reduce unnecessary treatments
d. Allow attention to be focused elsewhere
2. Identify the need for additional therapy
a. Identify and modify undesirable trends
b. Identify need for additional diagnostic
studies
3. Avoid lethal outcome
a. Initiate action without diagnosis
b. "Extremes" monitoring
c. Alarm functions
4. Guide ongoing therapy
a. Titrate therapy
b. Discontinue therapy as soon as appropriate
5. Direct the use of intermittent diagnostic studies
a. Confirm suspected diagnosis
b. Identify false-positive findings
c. Reduce additional intermittent tests
respiratory monitoring (pulse oximetry and capnography) during surgery and anesthesia
has resulted in fewer lawsuits for poor outcome caused by inadequate ventilation and
hypoxemia. Lower malpractice insurance rates have been awarded to anesthesiologists
routinely using those techniques. [6] [44] Many believe it is not that the number or kind of
adverse outcomes from anesthesia has changed greatly because of devices, [22] [24] but their
use is strong defense against undetected hypoxia being the cause of an adverse outcome.
[23] [41] Anesthesiologists believe that monitoring with pulse oximetry is useful even though
no study has shown an improved patient outcome attributable to its use. [34] [35] The clinical
detection of hypoxemia (cyanosis) is difficult and inexact. Because irreversible harm
from hypoxia occurs rapidly and laboratory evaluation of arterial oxygenation is invasive,
delayed, and expensive, oximetry, with its many faults, has been accepted as an advance
in monitoring for hypoxia by those practicing in the OR environment. [11] Pulse oximetry's
appropriate place in the ICU has not been established, but it is widely used.
MONITORING'S EFFECTS ON COST OF CARE
The aforementioned purposes for monitoring parameters could improve the quality of
ICU care. Some of them may also reduce costs. Titration of expensive drugs to minimum
effective levels and discontinuation of unnecessary treatments as early as possible
generate obvious cost savings. Avoiding organ system complications such as renal failure
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by minimizing toxic drug effects would save money and improve outcome. Monitoring's
effects on costs are listed in Table 2 .
Some monitor use may result in increased costs. Besides the cost of the monitor itself,
monitoring may lead to further testing to confirm specific diagnoses. Those tests add
costs. Invasive monitors involve patient risks. Treatment costs of complications caused
by monitors must be assessed when calculating costs of monitoring. Risks of monitors are
related to the user's technical skills and experience. [20]
There are several other problems with the collection and interpretation of physiologic
data. The accuracy of the measurement is the first concern. Vascular waveforms undergo
various alterations in traveling through the patient's vascular tree and the monitoring
systems. The problems with damping and resonance are well known. The need to
maintain a constant zero reference point and internal or external calibration is understood
by most anesthesiologists. Most problems with inaccurate data acquisition relate to those
areas. Proper selection and use of the electronic or physical display device are another
source of problems. When different monitoring equipment is in use in the OR and ICU,
the infrequent visitor may experience difficulty in obtaining the desired display or piece
of data. In a critical situation, that may result in fatal delay. This concern leads to the
recommendation that equipment and procedures be standardized between locations. In
addition, as part of a care team, the occasional visitor will need to depend upon and trust
other caregivers to provide technical help. The ICU team, unlike the OR team, is made up
of a large number of "interchangeable parts" that must provide a similar level of care and
expertise around the clock. ICU
TABLE 2 -- THE EFFECTS OF MONITORING ON COSTS AND BENEFITS OF
INTENSIVE CARE UNIT CARE
Direct costs of monitoring
Capital
Labor
Materials
Indirect costs and savings
Tests added
Tests avoided
Treatment costs added
Treatment costs avoided
Bedside-caregiver impact
Time lost to maintain monitor
Attention lost to false alarms
Time for additional tasks (telephone calls, time to perform additional tests)
Tasks reduced
Outcome benefits
Decrease in morbidity
Improved safety
Possibility other patients may receive more attention
Fewer caregivers needed
Side effects and risks specific to device
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care is much more of a team effort because of the need for constant caregiver presence
over a period of days.
The usefulness of physiologic data is enhanced by following a trend or change after an
intervention. Unlike many specialists, anesthesiologists rarely need a precise diagnosis to
proceed with treatment. We titrate depth of anesthesia by following changes in multiple
physical signs and physiologic variables. We don't even know what anesthesia actually is,
yet we empirically, successfully anesthetize patients daily. That empiric approach is also
important in critical care. When a cardiologist suggests "keeping the wedge at 10" he is
really saying that the preload should be on the low side of normal. That will reduce
myocardial oxygen demand but may compromise stroke volume. To know what the
actual wedge pressure number really means requires a fluid challenge to determine the
compliance or dose-response curve of the heart (Starling curve). A wedge pressure of 10
mm Hg could mean hypovolemia, euvolemia, or even hypervolemia; only the response to
fluid can determine which is the case. Once the significance of a specific pressure
number is determined, it may change over time. Measurements of response to repeated
infusions are often needed to assess the cardiovascular system.
Another important data analysis skill is the ability to evaluate several data sources. If the
wedge pressure recording is elevated but the neck veins are flat and the chest examination
does not detect rales, the determination that the patient is in pulmonary edema and needs
additional diuretic agents is in doubt. Weighing multiple data sources, often with
conflicting information, requires taking action despite diagnostic uncertainty.
LABORATORY DATA
Anesthesiologists generally use a limited number of laboratory examinations that are
rapidly available in the operating suite. In recent years, requests for a large number of
routine preoperative screening tests have been sharply curtailed. They contribute little to
care but increase cost. Symptom- or condition-directed testing has been the most costeffective approach. The ICU is different in several important ways. More tests can be
obtained but many take a longer time to perform. Specific diagnoses are sought over that
longer period of time. Standard and repeated laboratory test ordering is easy do in an ICU.
The clinician often has simply to enter the order and someone else will collect the sample,
send it off to the laboratory, and record the result. Standing, repeated laboratory orders
are easy to create. With indwelling lines, there is little patient discomfort and the
tendency is to "reduce uncertainty" by doing another test, even though the result will not
change therapy.
Too many laboratory tests are performed routinely on ICU patients, which results in the
need for additional blood transfusions, the chance
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of an erroneous result, and inappropriate care decisions. Optimum laboratory use can be
achieved by the use of explicit clinical indicators based on the patient's disease process
and therapeutic plans. Routine laboratory evaluations for monitoring should be used
infrequently. Civetta and Hudson-Civetta [7] and others identified excessive test ordering
as an ICU issue; 61% of all laboratory charges were generated during the ICU portion of
the patients' stay whereas only 15% of the total stay was in the ICU. They were able to
reduce laboratory use by 45% by altering physician test ordering behavior through
education, removal of standing orders, development of structured decision trees for
common clinical problems, raising acceptance of pulse oximetry, and decreasing
"routines" and arbitrary approaches to care. We introduced an arterial blood gas sampling
protocol that reduced the number of blood gas samples from 7.5 to 2.5 per patient per day.
[2] [4]
Making routine blood sampling more difficult has been suggested as a way to reduce
unnecessary laboratory use. The presence of an arterial line correlates with an increased
frequency of sampling. [33] This approach is draconian and subjects patients to painful
procedures. Better physician and nurse education, patient care algorithms, and guidelines
can achieve more rational use of laboratory analyses.
Point-of-care testing is becoming more common in the OR and ICU. Modular, reliable,
low-maintenance laboratory testing equipment is available for dedicated use in the
clinical environment. The touted advantage is that the time between sample acquisition
and analysis is reduced markedly and clinical decisions are hastened. Patient duration of
stay and laboratory personnel costs may be reduced. The downside is that additional
testing probably will be performed because of the convenience of the equipment; the
equipment is expensive; and the quality of the results is not validated by a professional
laboratory specialist. The cost-benefit analysis of this new approach to ICU testing
remains to be performed.
ROUTINE CHEST RADIOGRAPHY
Is a daily routine chest radiograph justifiable in all critically ill patients? How many
unexpected changes will be found? Several studies have attempted to address those
questions. Brunel and colleagues [5] compared the ability of clinical examination versus
radiographs to correctly identify endotracheal tube position in 219 critically ill adult
patients. Fourteen percent required repositioning after reviewing the radiograph despite a
normal detailed physical examination; 5% of the intubations resulted in a right mainstem
location. The authors concluded that chest radiography was required to confirm
endotracheal tube location, especially after an emergency intubation.
In pediatric patients, Hauser et al [19] found an even higher percentage of abnormal
endotracheal tube location. In reviewing 1003 chest films in a surgical ICU, Fong et al [13]
found significant abnormalities in 17% of
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films obtained with no clinical indication (routine), 26% of which were done for
verification of device location, and in 30% of cases in which there was a specific clinical
concern. The radiographic findings resulted in many interventions and suggest that chest
radiographs are a useful adjunct to the clinical examination. The films in stable patients
without invasive devices rarely led to a change in therapy, so "routine" films can be
avoided safely in this group.
Similar results have been shown in medical ICU (MICU) patients. Greenbaum and
Marschall [17] determined the value of 200 daily, morning radiographs in the MICU.
Although 37% were technically suboptimal or delivered too late for morning rounds,
43% of the others demonstrated significant, unexpected changes. As a result, the authors
[17] recommend continuing the current practice of obtaining at least daily radiographs in
the critically ill, and improving systems to allow caregivers access to the films in a more
timely manner.
It is reasonable to obtain and examine a daily chest radiograph in all patients in the ICU
who are on mechanical ventilation, have a central vascular catheter, or are being actively
treated for cardiopulmonary disease. Immediate films should be obtained after intubation,
line placement, or following significant clinical changes. If a patient has had a film for
one of those indications within 24 hours and is stable, then no routine daily film is
obtained until the following day. At least half the films can be expected to demonstrate
significant findings and about a third, to result in alteration of care. All films must be
examined by the clinician caring for the patient.
PATIENT ACUITY AND QUALITY ASSESSMENT
Anesthesiologists are familiar with patient preoperative risk assessment. The American
Society of Anesthesiologist's (ASA) physical status assessment score, with risk classes 1
through 5, is universally used to stratify patients' chances for anesthetic complications.
Similar approaches are used to assess the risk of groups of patients admitted to the ICU.
Such predictors of outcome can be used to evaluate treatment differences (research),
identify outcome outliners, or compare a unit's effectiveness to an internal or external
standard (quality measure). Several acuity-adjusted outcome systems have been
developed and validated for predicting mortality of ICU patients. One of the best known
and most widely used ICU mortality predictive systems is the Acute Physiology and
Chronic Health Evaluation (APACHE) scoring system. The APACHE II score is based
on the patient's age, presence of chronic disease, the patient's source of referral, and a
weighted score based on the worst deviation from normal of 17 physiologic measures
during the first 24 hours in the ICU. [26] The system has been validated in many different
ICUs and among different countries. It predicts about 90% of the outcome (alive or dead
at hospital discharge) of groups of critically ill patients. Differences between predicted
and actual outcome in an individual ICU can be used as a measure of quality or potential
quality
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problems relative to the "average" ICU outcome represented in the original APACHE II
data set. The predictions are based on data that are more than 15 years old.
A newer version of the system, APACHE III, is a commercial product with a larger set of
diagnosis-specific outcome predictions with a slightly different physiologic data set. [28]
Outcomes can be compared between similar institutions, units within the same region, or
with the entire database. Periodic updating and calibrating with current data makes the
comparisons more useful over time than the original APACHE II system. Similar to
APACHE II, slightly more than 90% of the patient's outcome is determined by the status
of the patient on ICU admission during the first 24 hours of treatment. A significant
improvement in the APACHE III system is the daily prediction of the probability of death
in each individual patient, based on algorithms relating to expected physiologic
improvements over time and development of organ system failures. Patients who have
less than a 10% chance of needing ICU resources are also identified with the APACHE
III system. [29] Those patients are only being monitored and can often be cared for in a less
intensive (and expensive) hospital location, with minimal risk of a worsened outcome.
That is an important tool for managing critical care resources.
Other models predicting ICU patient mortality include the Mortality Prediction Model, [32]
the Simplified Acute Physiology Score, [31] the Trauma Score and the Injury Severity
Scale [3] the Pediatric Risk of Mortality system, [36] and Project Impact, a growing ICU
database initiated by the Society of Critical Care Medicine. These systems can also be
used to stratify patients according to risk of death and, when applied across units, identify
quality concerns. Other quality measures should be collected in all ICUs. They include
monitoring the frequency of complications of critical care treatment. The incidence of
unplanned patient extubation, invasive line removal, pneumothorax during central line
insertion, cardiac arrest, incorrect drug or drug dosage, unexpected return to the operating
room, nosocomial infection, need for reintubation after elective extubation, pressure ulcer
formation, and death or return to the ICU after discharge have been used to identify
quality issues in the ICU.
A recent change in the accreditation process is the requirement that physician-specific
quality information be used in issuing and renewing credentials. Patient outcome
information, including mortality and complications, can be used to meet those
requirements. It is essential that case-mix-severity adjustment be included to improve the
accuracy and validity of the measures. Scoring systems help provide the calibration.
ICUs with better-than-predicted acuity-adjusted outcomes have been identified. The data
suggest there are organizational and care delivery methods that may contribute to
improved outcome. From the original APACHE study of 13 ICUs, the best units (those
that had better-than-predicted outcomes) had a patient-centered culture, strong medical
and nursing leadership, effective communication and coordination, and
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an open, collaborative approach to solving problems and resolving conflict. [27] In a study
of pediatric ICUs, the presence of a certified intensivist as unit director and a senior
physician decision maker in the unit correlated with the best patient outcome. [36] Other
studies have confirmed the contribution of an intensivist as unit medical director to
improved outcome. The complexity and differences in ICU organization, missions,
resources, and patient populations make it difficult to state generalities relating to
different management strategies. The best ICUs are concerned about the quality of patient
care delivered, attempt to measure quality, and change operations when opportunities to
improve are identified.
Patients undergoing surgical procedures experience a lower acuity-adjusted mortality
than medical patients admitted to an ICU with similar physiologic derangements. That is
because of the acute, reversible physiologic abnormalities induced by anesthesia and
surgery. Surgical patients experience more pain in the ICU than medical patients and are
often inadequately treated with analgesics. The advent of novel pain relief strategies (i.e.,
epidural analgesia, patient-controlled analgesia) has positively impacted critically ill
surgical patients and probably has reduced perioperative complications and mortality. [43]
Patients are admitted to an ICU for active treatment (such as mechanical ventilation,
vasoactive drug infusions, or airway protection) or for "monitoring." Patients being
monitored have a low frequency (generally < 10% chance) of needing active treatment
and experience a relatively low mortality--usually less than 5%. Between 20% and 40%
of ICU admissions to average surgical ICUs are for monitoring. The amount of active
treatment a patient is receiving can be quantitated in several ways. The Therapeutic
Intervention Scoring System (TISS) is a commonly used method that reflects the quantity
of care being received and correlates well with ICU costs. [25] TISS points do not correlate
with severity of illness because they are determined by local physician and nursing
treatment practices. The relative cost of ICU treatment can be estimated from the TISS
points when personnel costs are attached to the coded procedures. The updated TISS
point system is shown in Table 3 . Any unit manager interested in identifying and
controlling costs will employ some system to calculate expenses gauged against severity
of illness.
CRITICAL CARE RESEARCH
Many of the widely accepted treatment approaches used in the critically ill have never
been subjected to critical, scientific proof of effectiveness. [12] The quality of information
published about critical care treatments varies. There are few randomized, prospective,
blinded, controlled trials in the literature. Most useful information comes from other
investigative techniques, including cohort studies with historic or contemporaneous
controls, case-control studies, and case series. Often, information from several studies is
combined in a meta-analysis. Much of
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TABLE 3 -- THE COMPONENTS OF THE THERAPEUTIC INTERVENTION
SCORING SYSTEM (The TISS Score is the Sum of All Points)
Modified from Keene AR, Cullen DJ: Therapeutic intervention scoring system; update
1983. Crit Care Med 11:2, 1983; with permission.
Four-point interventions
Cardiac arrest or countershock within 48 hours
Controlled mechanical ventilation
Muscle relaxants
Balloon tamponade of variceal bleeding
Arterial infusion
Pulmonary artery catheter
Cardiac pacing
Peritoneal or hemodialysis in an unstable patient
Induced hypothermia
Pressurized blood transfusion
Military anti-shock trousers
Intracranial pressure monitoring
Platelet transfusion
Intra-aortic balloon pump
Emergency operation in past 24 hours
Gastric lavage for gastrointestinal bleeding
Emergency endoscopy or bronchoscopy
More than one vasoactive drug infusion
Three-point interventions
Central hyperalimentation
Pacemaker on stand-by
Chest tubes
Intermittent mandatory ventilation
Continuous positive airway pressure
Potassium bolus
Intubation
Nasotracheal suctioning
Complex metabolic balance
Lab studies greater than four per shift
Blood products greater than five per day
Multiple (not scheduled) boli of drugs
Single vasoactive drug infusion
Arrhythmia drug infusion
Cardioversion
Hypothermia blanket
Arterial line
Digitalization within 48 hours
Active diuresis for fluid overload or cerebral edema
Active treatment for metabolic alkalosis
Active treatment for metabolic acidosis
Emergency thora-, para-, or pericardiocentesis
Active anticoagulation initiated in past 48 hours
Phlebotomy for volume overload
Administration of more than two antibiotic agents
Initial treatment of seizures or metabolic encephalopathy
Complicated orthopedic traction
Two-point interventions
Central venous pressure monitoring
Two peripheral intravenous catheters
Hemodialysis-stable patient
Tracheostomy in previous 48 hours
Spontaneous ventilation through an artificial airway
Gastrointestinal tube feedings
Replacement of excess fluid loss
Parenteral chemotherapy
Hourly neurologic checks
Multiple dressing changes
Pitressin infusion
One-point interventions
Electrocardiographic monitoring
Hourly vital signs
Single intravenous catheter
Chronic anticoagulation therapy
Intake and output recording
Emergency blood tests
Intermittent scheduled medications
Routine dressing changes
Standard orthopedic traction
Tracheostomy care
Decubitus ulcer
Urinary catheter
Supplemental oxygen by mask or cannula
Chest physiotherapy
Extensive wound care
Gastrointestinal drainage
Peripheral hyperalimentation
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what is done in critical care depends on consensus development conferences in which
acknowledged experts share opinions and develop a document that is reduced to the
common elements this can be agreed upon. There has been a trend recently to qualify and
quantitate the information supporting consensus document statements. This is helpful in
separating belief from fact and identifying areas in which additional research is needed.
Unlike the case in the OR, where a single clinician decides what is to be done and then
does it, the ICU consists of many caregivers, each of whom has his or her role in the
delivery of care. As many as 50 different individuals may see an ICU patient during a
single day. Each individual brings biases and past experiences to the care process. The
ICU care plan often is the result of negotiation. To change from the "routine" is difficult
and involves risks. If a physician wants to give a new drug or an old drug through a new
route, the system will resist the change. The education and negotiation begin at the
bedside while the
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physician is presenting his plan. After convincing those present that it is a reasonable idea,
the plan may fail later, at change of shift, because new caregivers have not heard the
arguments supporting the departure from standard procedure or may not understand
exactly what was to be done. The system tends to return care to the "usual."
True advances in critical care practice are equally difficult to establish. Information
relating to critical illness is published in more than 60 weekly and monthly journals. It is
impossible to remain current in all areas, and what works in a controlled environment
may be worthless in the real world of critical care.
Clinical utility is the ability of a device or treatment to achieve its ascribed goals under
controlled circumstances. Monitoring devices, for example, have been evaluated for
clinical utility. Evaluation of a monitor includes demonstration of accuracy and
correlation with other known effective monitors. It also includes demonstrating that the
monitor contributes to a desired outcome with a known disease process in prospective,
controlled studies performed in carefully selected clinical situations. Some physiologic
monitors have been tested in that way and regarding accuracy, predictability, and
correlation with expected outcome.
Clinical effectiveness, on the other hand, is the ability of the device or treatment to
achieve the same desired results under less rigorously controlled use. [21] In general, that
level of proof has not been demonstrated with any monitor and with few therapies in the
ICU.
For monitoring devices and equipment, a middle ground may be clinical usefulness. This
concept reflects the balance among accuracy, ease of use, and production of meaningful
information. A device is used only if (1) its use is mandated by policy, (2) it is believed to
be "worth the trouble" by the user (if given a choice), or (3) it is both mandated and
useful.
Cost effectiveness of a treatment or device implies that, in addition to being clinically
effective (or at least useful), it costs less or incurs less risk than other accepted treatments.
New technology and treatments should not be introduced unless they are (1) less costly
and at least as effective as the current standard, (2) more costly but more effective and the
added benefit is worth the added cost, or (3) less effective and less costly but the benefit
of standard treatment is not worth the added cost. [8] [15] [30]
Changes in CCM practice will occur in the coming years. Decisions regarding treatment
will be modulated by cost considerations. The financial survival of the health care
institution may depend upon it. Using data and analyses or cost-effectiveness, providing
appropriate care at lower cost is possible. As previously mentioned, standardized
treatment approaches under the control of guidelines or algorithms offer promise of
quality and cost improvement in the ICU.
Protocols for weaning patients from mechanical ventilation are frequently used in critical
care units. Most of them were designed to decrease hours of mechanical ventilation and
establish acceptable methods of withdrawal of support. They are often based on the
techniques
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preferred by the attending physician or the unit's physician manager, but may be
developed in conjunction with the respiratory therapy and nursing staff. They are specific
to the unit population and often reflect unit organization and coverage patterns.
Extubation after a certain hour (i.e., midnight) may be forbidden, for instance, because of
unavailability of personnel skilled in airway management at night. Whether weaning is
performed with t-piece trials or reduction in intermittent mandatory ventilation rate or
pressure support level, it should be performed in a consistent, gradual, step-wise fashion
that can be described by a flow chart or algorithm. A unit-specific, diagnosis-specific
plan can be developed and consensus developed to allow weaning to occur predictably.
Allowing independent assessments and decisions (within the framework of the algorithm)
by nonphysician caregivers (nurses and respiratory therapists) improves consistency and
efficiency. The amount of latitude given to therapists and nurses in weaning patients
depends upon their skill level, consistency of coverage, and the trust they have developed
with the physician staff.
Patient-driven protocols (PDPs) for weaning patients from mechanical ventilation may be
more efficient than traditional physician-therapist-decided weaning. Wood and others [42]
evaluated the effects of initiating a PDP for IMV weaning in a surgical ICU. They
compared the incidence of respiratory problems, duration of mechanical ventilation, and
duration of weaning when cardiac surgery patients were changed from weaning by
physicians to weaning by PDP. They found no change in complications and a slight
decrease in total duration of mechanical ventilation with PDP weaning (18.6 versus 16.8
hours). There was an insignificant decrease in weaning time, from 3 hours to 2.2 hours.
The PDP they developed was very restrictive, allowing a maximum decrease of six
breaths per hour in IMV rate and mandating arterial blood gas analysis after every
ventilator change.
After safety was demonstrated in stable cardiac patients, physicians were permitted to
order PDP weaning for other patients. Over an approximately 7-month period, the
percentage of patients weaned by PDP rose progressively to 90%. Entrance criteria were
liberalized operationally (but not changed formally) and many less stable patients were
weaned and stable patients were entered into weaning earlier. The statistically significant
shortening of total time of mechanical ventilation persisted throughout the study periods.
Interestingly, even physician-weaned patients had a shortened duration of mechanical
ventilation during the later part of the study compared with the control period. The use of
a protocol by therapists seemed to increase the efficiency and consistency of weaning by
physicians when the PDP was not in use.
Although statistically significant, the changes observed in duration of mechanical
ventilation (2.1 hours) probably had little economic impact. The significance of the
introduction of PDP weaning was the increased confidence that physicians developed in
the respiratory therapists' abilities to assess patients and make independent management
decisions. Therapists' suggestions become more consistent among
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practitioners. Only 4% of patients failed PDP weaning in the study. The expanded use of
nonphysicians in the ICU is likely to continue. Working as part of a multidisciplinary
team is a skill practiced daily by anesthesiologists. Comfort with that arrangement is
necessary for ICU survival.
Changes in payment and control of health care costs will effect changes in management
of critical care units. As integration of individual institutions into cooperative care
delivery systems becomes necessary, integration within component organizations must
also occur. ICUs no longer can be viewed in isolation from the rest of the hospital.
Hospitals must see themselves as part of a system in which groups of patients are
provided health care. Institutions are combining resources to reduce unnecessary market
competition and achieve savings of scale and reduction of redundancy. Home health care,
skilled nursing homes, outpatient clinics, and the hospital must achieve integration,
focusing on the patient's (or a population of patients') needs rather than marketing an
expensive (unnecessary?) service. The patient's disease takes center stage and care must
be provided efficiently in the most appropriate area of the system. [16] Prevention and
control of hospital admissions are implicit in the financial strategies of managed care
plans. The provision of critical care services is a very costly activity for a hospital.
Prevention of avoidable ICU admissions can save institutional resources. Because many
patients are admitted to an ICU after respiratory deterioration on a hospital floor,
improved pulmonary assessment and care outside the ICU should assume a high priority
for the ICU manager. Improvements can be achieved by prospectively identifying
patients at risk for respiratory failure and intervening with less invasive techniques,
possibly preventing the need for mechanical ventilation. For patients needing ICU care,
early identification and treatment of respiratory failure should result in a shorter duration
of ICU and hospital stay and better survival. By thinking of the continuum of care sites,
each therapist can expand his or her role to one of respiratory disease management, the
intent being to avoid preventable, higher cost care, and to improve patient outcome
through earlier intervention.
One high-risk group comprises patients discharged from an ICU. Many are recovering
from respiratory failure and may require ICU readmission, which is expensive and carries
a high risk of mortality. Franklin and Jackson [14] examined 36 readmissions to a medical
ICU and found a mortality rate of 58%, compared with 12% mortality of all medical ICU
patients. Rubins and Moskowitz [39] reported a 16% unexpected readmission rate or death
on a hospital floor after discharge from a medical ICU. The mortality rate in the patients
was 57%. Respiratory problems were responsible for most of the readmissions in their
study.
Baigelman, Katz, and Geary [1] studied readmissions to any of four ICUs in a community
hospital. They found an 11.7% overall readmission rate and believed that as many as 36%
of those patients were discharged prematurely. Included in their study were a significant
number of patients with acute myocardial infarction, perhaps accounting for the rather
low mortality rate (21%) reported in that group of readmitted
895
patients. In a report of readmissions to a surgical ICU, Snow and others [40] found a
mortality rate of 26% in a group of 57 patients readmitted, representing 9.4% of the total
ICU admissions.
We previously identified respiratory deterioration as the most frequent cause resulting in
the need for ICU readmission. In our tertiary care hospital, 54% of patients were
readmitted to medical and surgical ICUs for respiratory deterioration. [10] Forty-seven
percent of the readmitted patients expired before hospital discharge. Following our initial
study, we instituted several changes to address respiratory issues on the hospital floors,
including establishment of a dedicated floor therapist assessment team, [18] use of
respiratory treatment algorithms, [4] and continuous staff education programs, [2] in an
attempt to improve respiratory care after ICU discharge. The goals were to continue
aggressive respiratory care after ICU discharge, and, hopefully, reduce readmissions for
respiratory failure.
We recently restudied the issue. [9] Although acute respiratory deterioration remained the
most frequent cause for ICU readmission (45%), the mortality of readmitted patients
plummeted to 12% overall and 19% for those with a primary respiratory problem
resulting in ICU readmission. With active attention on the floors, definitive treatment
more frequently was started prior to arrival at the ICU. Providing frequent respiratory
monitoring and appropriate care on leaving the ICU, especially to those at high risk, has
improved the outcome in patients readmitted.
The change in acute care management strategy had no effect on ICU duration of stay or
overall ICU readmission rate. The average number of days spent in the ICU on the first
admission was 8.3 in the most recent study versus 6.3 in the previous study ( p=0.165, t
test). Readmitted patients in the previous study remained out of the ICU 5.9 days,
compared with 6.7 days in the recent study period. Prior to instituting the changes, 4.7%
of ICU discharges were readmitted; after the changes, 4.7%. Attention to the potential for
respiratory failure in this high-risk population and provision of respiratory care across
several care sites have improved quality (reduced mortality) and (probably) reduced costs.
The development of step-down care units has had similar effects in other institutions. For
cost-effective care in a competitive marketplace, the continuum of care sites must be
integrated and patients provided care in a seemless fashion. The traditional borders of the
ICU must be lowered and patients' needs met in what ever environment is most
appropriate. That requires considerable flexibility on the part of caregivers and managers.
Many sources of data are available to the individual working in an ICU. Understanding
the meaning, sorting, and weighting of each element is necessary for appropriate decision
making in the ICU. Information from laboratory studies, physiologic monitoring, and the
patient's physical examination must be integrated to make a clinical decision on care.
Information from population studies, comparison with other units, and quality data can
improve processes and the unit's functioning in general. The cost of care is everyone's
concern and making cost-effective
896
changes is a new idea for many physicians. Seeing oneself as contributing to a team effort
rather than controlling patient care is the attitude necessary to the future development of
health care delivery. By understanding the many kinds of data, anesthesiologists can be at
the forefront of these developments.
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W, Katz R, Geary G: Patient readmission to critical care units during the same hospitalization
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8. Detsky
AS, Naglie G: A clinician's guide to cost-effective analysis. Ann Intern Med 113:147-154, 1990
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TJ, Fischer EP, Leibowitz AB, et al: Physicians' knowledge of the pulmonary artery catheter.
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WA, Wagner DP, Draper EA: Identification of low-risk monitor admissions to medical-surgical
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Guest Editor's Commentary
Data in the Intensive Care Unit
Philip D. Lumb MB, BS Guest Editor
"The best ICUs are concerned about the quality of patient care delivered, attempt to
measure quality, and change operations when opportunities to improve are identified."
Durbin introduces two key driving forces that forced the logical development of critical
care units: "Patients required rapid, specific interventions to prevent physiologic
deterioration or death, and hospitals needed to effectively and efficiently provide
necessary levels of service." That introduction of both patient- and business-driven
requirements provides a framework on which discussion of the following topics is placed:
physiologic data and monitoring, laboratory data, outcomes information and prediction
systems, critical care research, and cost/quality information. He prefaces his remarks by
underscoring the characteristics that make anesthesiologists influential practitioners in the
difficult clinical environment of CCM: "(1) the ability to lead a team of professionals
inconspicuously and (2) the ability to analyze massive amounts of data efficiently and act
appropriately and rapidly on sometimes conflicting results." The concepts of predictive
analysis and cost-effective resource management are added to this provocative discussion
of the developing role of the anesthesiologist intensivist. Indeed, it is in that light that the
article must be analyzed. Durbin has taken a routine topic and promoted it to become the
platform from which an important new discussion of critical care practitioner
responsibility and prerogative must be initiated. That topic is suggested in the statements
pertaining to clinical utility and clinical effectiveness. It is highlighted in the discussion
regarding decreasing the cost of care with dependent protocols developed between
physician and skilled ancillary health care providers and the value of appropriate floor
care and triage in decreasing complications, ICU readmission rate, and overall patient
mortality. Durbin provides fresh insight into the clinician's responsibility to collect and
analyze data correctly; more importantly, he highlights the futility of monitoring without
appropriate, indicated intervention.
The logic of Durbin's article is inescapable, yet the current practice standard in many
ICUs and operating rooms ignores the aforementioned principles and indicates to an
observer that data collection is less patient-care driven and more regulatory responsive
than appropriate for today's difficult clinical practice environments. The reasons why that
is the case are multiple and complex, not the least important of which have to do with
tradition and the confusion of roles and prerogatives in the ICU itself. In some instances,
data are available, but appropriate action is
899
either impossible or delayed in the face of regulations that proscribe intervention by some
practitioners or threaten the therapeutic imperative of others. In addition, and perhaps
equally important, the manner in which data are acquired, displayed, and, perhaps
therefore, interpreted has not changed significantly in the past 25 years. The automated
physiologic profile described by DelGuercio in the 1970s provided the same data in a
more useable format than is available in many ICUs today. A completed profile both
provided insight into the patient's condition and reminded the clinician of the physiologic
principles underlying suggested therapeutic interventions. It was an advocate of early
nutritional support, a strangely simple initiative that continues to lack vigorous supporters,
and it provided a graphic, temporal snapshot of the patient's condition. That feature
permitted rapid evaluation of therapeutic interventions, and rapid therapeutic titration was
possible across a range of interventions. Durbin's contention that the anesthesiologist is
positioned to work in this environment is well founded. A similar condition has existed in
the operating room, in which much of the effort in automated data collection has been to
reproduce the anesthetic record electronically rather than to provide the clinician with a
more appropriate data set upon which to base therapeutic intervention.
The analogous situation does not exist in the profession to which anesthesiology is often
compared--piloting an aircraft. There is no doubt that aircraft pilots consider the job of
landing an expensive piece of hardware on an unstable platform in all weathers to be a
challenge but one for which they are well trained and electronically supported. Indeed,
the final approach can be subjected to physical and mathematical interpretation and
simulation, and a yardstick has been developed against which the pilot can judge the
effectiveness of the approach--the ball. During final approach and landing, the pilot is
required to keep alignment of a lighted ball in a heads-up display graticule. The task is
not easy, but the payoff is significant. Correct alignment is possible only if numerous
characteristics about the plane's attitude, altitude, glide path, speed, angle of descent, and
others are appropriate for the specific conditions existing on the flight deck at the time of
the expected landing. Responsive to different aircraft and in all weather conditions, the
technology has advanced to the point of making it easier for the pilot to concentrate on an
output that integrates numerous, complex data sets and translates their interactions into an
understandable, useable, and actionable signal. Indeed, with the complexity and speed of
modern aircraft, it is unlikely that the carrier-based support wings could have been
deployed effectively in the absence of advanced, integrated, and functional technology.
Unfortunately, the same care in data processing, integration, analysis, and display has not
been a priority in either the operating room or the ICU. Technology's outputs have
remained vendor-specific until recently, and integrating different signals has negative
financial implications for companies producing proprietary hardware with individual,
single-channel printers. One has only to look at the back of an ICU flowsheet to see the
individual traces taped to the
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back of the cart, indicating either a new calibration or an observed dysrhythmia. That has
worked reasonably on an individual basis, but recovery of the information for
comprehensive risk management and quality analysis is virtually impossible, promoting
the myth that we can't expect the outcome of biologic dysfunction to be as predictable as
that of a physical object with defined characteristics and a known destination. The
argument is persuasive and may be valid; the fact is that we cannot articulate an argument
either for or against because the integrated, analyzed, and appropriately displayed data
are lacking despite collection of their components. Gene Roddenberry recognized the
importance of this concept when he provided Star Trek's Enterprise capabilities that we
can but admire today; remember the monitors displaying "brain metabolism," "cellular
function," and "life force?" Modern technology may be capable of approaching those
outputs cost effectively; it will be up to clinicians to demonstrate the need and the
willingness to "fly by the ball," a new sensation for many and one that will require
empowerment of new providers on the CCM team.
Durbin explores these issues more practically and less fancifully than my comments, and
his insightful approach to the subject is to be commended. It is likely that his premise
regarding the anesthesiologist's important role in this arena can be supported if the
activities of more practitioners extend outside the operating room into the perioperative
arena, to include that of the ICU and other high-dependency units. The imperatives to
succeed are great; decreased resources, increased clinical demands from increasingly
complex diseases and procedures, and a commitment to excellent patient care require a
new and more effective clinical armamentarium. Improving data collection, analysis, and
display in the ICU is a vitally important requirement in the future paradigm and one in
which anesthesiologists provide the human template for the desired electronic outcome.