Page 50 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 3: Intensive Care Unit Staffing 19

employment of nonphysician providers can be financially burdensome. database in Maryland. 114-116 These assessed whether LOS was longer
The salary of an NP or PA is nearly twice that of a resident. 95,96 Some of for patients when PNR >2 versus ≤2, separately during daytime and
this increased cost, however, may be offset by cost savings associated nighttime nursing shifts. While hospital LOS was significantly associ-
with nonphysician provider-based care. 77 ated with PNR >2 at night for abdominal aortic surgery and esopha-
The nonphysician provider is an often untapped resource, which gectomy, it was not for hepatectomy. Harder to explain mechanistically
should be considered for use in the care of adult ICU patients. While is that longer hospital LOS after abdominal aortic surgery patients was
data are limited, care provided by NP/PA-based teams appears to be associated with PNR >2 on night but not day shifts, while ICU LOS
safe and, in many instances, comparable to that provided using other was associated with PNR >2 on day but not night shifts. 114
staffing models. A handful of studies reported that higher PNR was associated
with higher hospital costs, higher reintubation rates, and adverse
events. 109,115,116,126-128 Curiously, one study of adverse events among all
BEDSIDE NURSES
patients in 205 European ICUs on a single day found that the relation-
Nurses are the lynchpin of ICU care. Unlike other ICU HCWs, they are ship had an inverted U-shape, that is, lower risk of such events for both
with the patients most of the time. They perform most of the numerous high and low ratios. 128
97
interventions conducted daily on ICU patients. 98 In addition to the data from adult ICUs, six studies of nursing
In this section, we review the existing knowledge about ICU staffing workload in pediatric or neonatal ICUs addressed a similar range of
by nurses, and nurse extenders. We will limit our review to ICU-specific outcomes as in the adult studies. 129-134 Half of these reported significant
data; wards differ from ICUs in many ways (eg, patient types, struc- associations. Higher PNR was associated with more infections in two of
tures, nursing tasks, prevalent patient:nurse ratios), making it unwise to these, 130,133 and with fewer unplanned extubations in another. 131
assume that findings in one area will apply in the other. Taken together, this literature is difficult and inconsistent, providing
Although the purpose of this section is to review the literature on no clear conclusions about whether ICUs would succeed in improving
issues related to ICU nurse staffing, the overarching nurse staffing issue outcomes if they added nurses to reduce their PNRs. Indeed, interpre-
is the nursing shortage. This shortage is substantial and worldwide. 99,100 tation is complicated by at least five factors. First, nursing workload
ICUs are not immune to this shortage 101,102 ; indeed, they may be particu- encompasses considerations other than gross ratios of patients to
135
larly affected. 103 nurses, but such considerations were included in few of the studies.
■ PATIENT:NURSE RATIOS Second, with the exception of three pediatric investigations, all
130,131,134
existing studies used measures of average nursing workload. Though
Numerous studies have tried to measure the association between the one might expect to observe an effect using such global measures, if it
workload of ICU nurses and clinical outcomes (Table 3-3). Most of these existed, it would be better to relate outcomes of individual patients to
analyzed patient:nurse ratios (PNRs), though a few used the related patient-specific measures of nursing workload. Third, in many ICUs
measure of nurse hours per patient-day. there are other HCWs who do some of the work historically performed
37,102
ICU PNRs vary substantially by country and ICU type. A 1:1 ratio by registered nurses (RNs). However, most studies excluded the
37
is the historical standard in many countries, and remains so in some. work done by nursing assistants, and even licensed nurses other than
7
104
In the United States in the early 1990s, even before the nursing shortage RNs. Fourth, the inconsistent findings could reflect the fact that this is a
was severe, the most common ratio was two patients per nurse. In diverse group of investigations that varied greatly by study design, work-
102
Germany the average ICU nurse cares for 2.7 patients, and this number load measures, adjustment for confounding variables, types of patients,
is higher during nighttime hours. California mandates that on all shifts and the existing standards for nursing workload. It seems quite possible
8
there be at least one licensed nurse for each two ICU patients, and that the effect on outcomes of adding additional nurses could be limited
105
the British Association of Critical Care Nurses believes that patients on to specific types of patients, and to ICUs with relatively high PNRs.
mechanical ventilation require a 1:1 ratio. While we should seek to Improving PNRs may show no benefit because those ratios are already
104
identify the optimal ratio, an inevitable result of the growing nursing so low in many ICUs. The final limitation relates to how the design of
shortage in conjunction with increased demand for ICU care 106,107 is that these studies mandates extreme caution in inferring that there is a causal
PNRs will rise regardless of what the data show. relationship between PNR and outcomes. Most studies in Table 3-3 were
Of 10 studies that assessed mortality, four reported that a higher multicenter and cross-sectional, comparing outcomes between ICUs
PNR was significantly associated with death, 108-111 while six did not. 112-117 with differing average nurse workloads. However, hospitals whose ICUs
The largest of these studies included 83,000 patients admitted to 40 have more nurses per patient may also be more likely to have superior
Austrian ICUs where the average PNR was 1.5 ; in an adjusted analysis administrative structures, more or better medical or information tech-
108
hospital death was associated with a higher PNR (OR = 1.3, p <0.05). nologies, and a better climate of patient-centered safety, variables that
The second largest study included over 33,000 patients in 171 Veterans have not been included in any existing study. Thus, it could be those
Administration ICUs where the average nursing hours/patient-day was other confounding factors, not the number of nurses, that are causally
17 (approximately equivalent to a PNR of 1.4) ; in a complex adjusted related to superior outcomes. It requires longitudinal analysis of nurs-
112
analysis hospital death was not associated with more nurse hours/ ing supply and outcomes to move beyond the associations suggested by
patient-day (OR = 1.01, p = 0.45). A large study from Korea found cross-sectional studies in order to understand causal relationships. This
higher mortality with higher PNR in community hospital ICUs, but has been demonstrated in studies of nursing supply in hospitals, not
136-138
not those in tertiary referral hospitals. An attempt at meta-analysis of ICUs. For example, using data over time from 414 hospitals, Mark
111
137
studies assessing mortality concluded that the data are inconclusive. 118 et al found that a cross-sectional analysis associated higher mortality
Eight studies evaluated ICU-acquired infections or bacterial coloniza- with a lower nursing supply. However, applying appropriate statistical
tion. 109,119-125 Five of these reported at least some significant association techniques to the longitudinal data, this benefit was restricted to hospi-
of higher rates of nosocomial infection with higher PNR, and two with tals with a low nursing supply at baseline. In addition, the lower infec-
nonsignificant findings had point estimates in the same direction. 119,124 tion rates seen in the cross-sectional analysis completely disappeared in
These studies differed greatly by size and analytic methods, and some longitudinal analysis.
mechanistically support the concept that a higher PNR has a causal rela- ■ NURSE TYPE, TRAINING, CERTIFICATION,
significant findings lacked monotonic dose-response relationships that
tionship with infection rates. 109 AND USE OF NURSE EXTENDERS
Three studies from a single research group that assessed LOS evalu- There are little data addressing these issues. While the majority of ICU
ated distinct types of complex postsurgical patients from a statewide nurses in developed countries are RNs, licensed practical nurses (LPN), and

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