Page 34 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 1: An Approach to Critical Care 3

illustrates a decreasing benefit as the intensity of the intervention and
the shock it masks continues. Armed with this rationale, the intensivist
should progressively reduce the intensity of norepinephrine infusion
over a relatively short period to determine whether the volume resusci-
tation is adequate.
Benefit treatment of pulmonary edema. In Figure 1-1 the intensity of the inter-
A second example is the use of fluid restriction and diuresis in the
vention is the achievement of negative fluid balance while the benefit
would be the reduction of pulmonary edema. Considerable data suggest
a monotonic relationship between the intensity of these therapeutic
11
Intensity interventions and the benefit of reduced pulmonary edema. Yet, if
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intravascular volume is reduced too much, there is a consequent reduc-
FIGURE 1-1. A schematic diagram relating therapeutic intensity (abscissa) to the benefit tion in the cardiac output, so the benefit to the patient is more than
of therapy (ordinate). For many interventions in critical illness, there is a monotonic increase offset by the attendant hypoperfusion state. The thoughtful intensiv-
in benefit as treatment intensity increases (solid line), but concomitant adverse effects of the ist recognizes that the goal of reducing pulmonary edema should not
intervention cause harm at higher intensity (interrupted line) (for examples, see text). This induce a hypoperfusion state, so the targeted intensity is the lowest
leads to an approach to critical care that defines the overall goal of each intervention and seeks intravascular volume associated with an adequate cardiac output and
the least intense means of achieving it.
oxygen delivery to the peripheral tissues.
the patient with hemorrhagic shock treated with volume resuscitation ■ FIRST DO NO HARM
and blood products also acutely receives intravenous vasoconstricting Beyond enhancing the clinical scholarship of critical care, this approach
agents to maintain perfusion pressure while hemostasis and volume maximizes another hallowed principle of patient care—“First do no harm.”
resuscitation are achieved. Once a stable blood pressure and hemostasis Despite excited opinions to the contrary, effective critical care is rarely
are achieved, what is the time course for discontinuing catecholamines? based on brilliant, incisive, dramatic, and innovative interventions, but
One answer is to wean the vasoconstrictor slowly (eg, decrease the most often derives from meticulously identifying and titrating each of the
norepinephrine infusion rate from 30 by 5 µg/min each hour). Another patient’s multiple problems toward improvements at an urgent but continu-
approach is to liberate the patient from the vasoconstrictor by reducing ous pace. This conservative approach breeds skepticism toward innovative
the norepinephrine infusion rate by half every 15 minutes. The dif- strategies: Novel treatments require objective clinical trials before they
ference between these two approaches is more than the time taken to are implemented, and traditional therapies require clarification of goals
discontinue the agent, for if in the second approach the blood pressure and adverse effects in each patient before their use can be optimized. 12-14
were to fall after reducing the norepinephrine to 15 µg/min, the critical Accordingly, intensivists should carefully consider the experimental sup-
care physician learns that the patient remains hypovolemic and needs port for each diagnostic and therapeutic approach to critical illness and
more volume infusion; the first approach would mask the hypovolemic acknowledge that each approach has adverse effects in order to define the
hypoperfused state by the prolonged use of vasoconstrictor agents, least intensive intervention required to achieve its stated therapeutic goal.
leading to the adverse consequences of multiple organ hypoperfusion.
Words convey meaning, and to wean connotes the removal of a nur- ■ ORGANIZE THE CRITICAL CARE TEAM
turing, even friendly life-support system from a dependent, deprived
infant, a process that should proceed slowly; by contrast, liberation is The ICU has long evolved beyond a room in which ventilators are used.
the removal of an unnecessary and potentially toxic intervention from Instead, in a well-functioning ICU, the physical plant and technology are
8
an otherwise independent adult, a process that should proceed urgently. planned to facilitate the delivery of care, while also responding to new
Similarly, other aspects of critical care management as simple as bed opportunities in this rapidly evolving field. The physician director, the
rest and sedative administration are best approached as treatments from nurse manager, and the team of respiratory therapists, pharmacists, and
which the patient should be liberated at the earliest opportunity. 9,10 physiotherapists must build a mutually supportive environment condu-
■ DEFINE THERAPEUTIC GOALS AND SEEK THE LEAST Intensivists must be aware of the economic and legal concerns as ICUs
cive to teaching, learning, and care.
INTENSIVE INTERVENTION THAT ACHIEVES EACH capture the interest of politicians, ethicists, and the courts. Furthermore,
the managers of ICUs should build on experience. Quality assurance,
Thus the principle that “less is more” applies to many critical care thera- triage and severity scoring, and infection surveillance are essential to
pies including bed rest, fluid therapy, vasoactive drug use, mechanical the continued smooth running of ICUs and indeed to their improve-
ventilation, and administration of sedative and muscle-relaxing agents. ment over time.
Of course, the difficulty in all these examples is that the therapeutic
intervention is initially necessary and/or lifesaving, but how long
the intervention needs to continue for the patient’s benefit versus the MANAGING DEATH AND DYING IN
patient’s harm depends on a critical evaluation of the goal of therapy. THE INTENSIVE CARE UNIT
Figure 1-1 indicates the intensity-benefit relationship of many of these
interventions (eg, the continued use of high-dose norepinephrine in the Perhaps no critical care issue is more emotionally charged and time-
hypotensive patient with hemorrhagic shock discussed earlier). During consuming than the decision to withhold and/or withdraw life-sustaining
the initial resuscitation, the benefit of increasing the norepinephrine therapy. Practitioners and students of critical care are frequently called
dose along the x-axis (intensity) was demonstrated by the rising blood on to guide patients and their families through this complex decision-
pressure during hemostasis, volume resuscitation, and norepinephrine making process. Accordingly, we discuss an approach to managing death
infusion. Yet blood pressure is not the appropriate benefit sought in the and dying in the ICU meant to minimize one current adverse outcome of
hypoperfused patient, but rather adequate perfusion of all organs. Even modern critical care—our patients die alone in pain and distress because
without measuring cardiac output, an adequate perfusion state could maximal care aimed at cure proceeds despite little chance of success.
agent is diminished. However, with continued infusion of the vasocon- ■ DECIDE WHETHER THE PATIENT IS DYING
be inferred from an adequate blood pressure when the vasoconstrictor
strictor, the adverse effect of a prolonged hypoperfusion state, even with In an analysis of 6110 deaths in 126 ICUs between January and July of
an adequate blood pressure, is indicated by the interrupted line, which 1996, approximately half were associated with the decision to withhold

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