Keywords
oxytocin - nurse staffing - patient safety
Oxytocin is used for labor induction or augmentation in approximately one-half of
all deliveries in the United States.[1]
[2] Because of the potential for uterine tachysystole and its adverse effects on the
fetus, careful monitoring of such women by nursing staff is essential.[3]
[4] Proposed approaches to improve such monitoring have included uniform training of
nursing staff in the interpretation of electronic fetal heart rate and uterine contraction
monitor tracings, the use of checklists, and the implementation of protocols that
standardize the administered oxytocin infusion rate.[1]
[2]
[3]
[4]
[5]
[6] In others areas of medicine, fixed staffing ratios have been investigated and occasionally
linked to improved patient outcomes, although most studies have not shown such a relationship.[7]
[8]
[9]
[10] Our purpose was to evaluate the effects of 1:1 nursing care for women receiving
oxytocin in labor, both from the perspective of patient safety and cost.
Materials and Methods
This study was performed in Hospital Corporation of America affiliated facilities,
which account for the largest number of inpatient obstetric services in the United
States, with over 200,000 deliveries annually in 110 affiliated hospitals in 21 states.
Approximately 6% of U.S. deliveries occur in these hospitals, and prior publications
have suggested that this system is fairly representative of the U.S. population as
a whole.[11]
[12] We analyzed data from January 1, 2010, to December 31, 2010. During this time, there
was no single, uniform staffing policy in Hospital Corporation of America (HCA)-affiliated
hospitals for women receiving oxytocin during labor. Instead, on-site nursing and
medical personnel were encouraged to use their judgment regarding appropriate staffing
ratios for all women in labor, with and without oxytocin infusion, depending on the
level of acuity demonstrated by individual patients.
Our study design included three parts. First, staffing ratios for women receiving
oxytocin were surveyed, and facilities divided into four groups based on the frequency
(0 to 25%, 26 to 50%, 51 to 75%, or > 75%) with which each facility provided 1:1 staffing
for such patients during 2010. These analyses were performed independently by the
labor and delivery nursing directors at each facility.
Second, we obtained coding-based data on pertinent perinatal outcomes for all women
receiving oxytocin for either induction or augmentation of labor at each facility
during 2010 ([Table 1]). The category of multiple complications includes women with more than one of the listed adverse outcomes. An additional neonatal
outcome, birth asphyxia (Diagnosis Related Groups (DRGs) 7685, 7686, 7689), was analyzed
from newborn records for the entire population of women delivering at each facility
during 2010. The data for each hospital were stratified into the four frequency categories
previously described.
Table 1
Relationship between nurse staffing ratio and intrapartum complications: oxytocin
induction/augmentation
|
1:1
|
n
|
Primary cesarean
|
OR[a] (95% CI)
|
Fetal distress
|
OR[a] (95% CI)
|
Amnionitis
|
OR (95% CI)
|
Endometritis
|
OR (95% CI)
|
Multiple complications
|
OR[b] (95% CI)
|
|
76–100
|
14,644
|
4,530 (30.9%)
|
1
|
2,544 (17.4%)
|
1
|
434 (3.0%)
|
1
|
59 (0.40%)
|
1
|
2,086 (14.3%)
|
1
|
|
51–75
|
24,704
|
7,382 (29.9%)
|
0.95 (0.91–0.99)
|
4,459 (18.1%)
|
1.05 (0.99–1.11)
|
587 (2.4%)
|
0.80 (0.70–0.91)
|
91 (0.40%)
|
0.91 (0.65–1.29)
|
2,446 (9.9%)
|
0.66 (0.62–0.70)
|
|
26–50
|
13,753
|
3,928 (28.6%)
|
0.89 (0.85–0.94)
|
2,541 (18.4%)
|
1.08 (1.01–1.15)
|
268 (2.0%)
|
0.65 (0.56–0.76)
|
40 (0.30%)
|
0.72 (0.47–1.10)
|
1,763 (12.8%)
|
0.88 (0.83–0.95)
|
|
0–25
|
48,676
|
15,649 (32.1%)
|
1.06 (1.02–1.10)
|
9,668 (19.9%)
|
1.18 (1.12–1.24)
|
1,245 (2.6%)
|
0.86 (0.77–0.96)
|
184 (0.38%)
|
0.94 (0.69–1.27)
|
5,637 (11.6%)
|
0.79 (0.75–0.83)
|
|
Total
|
101,777
|
31,489 (30.9%)
|
|
19,212 (18.9%)
|
|
2,834 (2.8%)
|
|
374 (0.37%)
|
|
11,932 (11.7%)
|
|
Abbreviations: CI, confidence interval; OR, odds ratio.
a
p < 0.0001.
b
p = 0.002.
Finally, we performed a gap analysis, comparing actual staffing levels with a hypothetical
model in which each patient receiving oxytocin during labor also received 1:1 nursing
care during oxytocin infusion. We analyzed this model both in terms of additional
full-time equivalents needed and the total cost of providing this hypothetical type
of care. We utilized previously published data from our system documenting a mean
duration of oxytocin infusion of approximately 8.5 hours for women receiving labor
induction or augmentation.[3] We then extrapolated our results to a second model in which 1:1 nursing care would
be provided to all women receiving oxytocin during labor in the United States ([Table 3]).
Table 2
Relationship between nurse staffing and birth asphyxia: all deliveries
|
1:1
|
n
|
Birth asphyxia
|
OR (95% CI)
|
|
76–100
|
28,605
|
104 (0.36%)
|
1
|
|
51–75
|
55,365
|
158 (0.29%)
|
0.78 (0.61–1.01)
|
|
26–50
|
27,503
|
105 (0.38%)
|
1.05 (0.79–1.39)
|
|
0–25
|
96,560
|
354 (0.37%)
|
1.01 (0.81–1.26)
|
Abbreviations: CI, confidence interval; OR, odds ratio.
Table 3
Oxytocin staffing cost analysis
|
n
|
% 1:1
|
Mean
|
Pts if 1:1
|
Additional pts if 1:1
|
h/pt
|
Excess FTE
|
$/h
|
Excess cost
|
|
14,644
|
76–100
|
86.5
|
16,930
|
2,286
|
8.5
|
9.7
|
30
|
582,930
|
|
24,704
|
51–75
|
62.5
|
39,526
|
14,822
|
8.5
|
63
|
30
|
3,779,610
|
|
13,753
|
26–50
|
37.5
|
36,674
|
22,922
|
8.5
|
97
|
30
|
5,845,110
|
|
48,676
|
0–25
|
12.5
|
389,408
|
340,732
|
8.5
|
1,448
|
30
|
86,886,660
|
|
101,377
|
Total
|
|
|
|
|
1,618
|
|
97,094,310
|
Abbreviations: CI, confidence interval; FTE, full-time equivalent; OR, odds ratio;
pt, patient.
Note: Calculation example, first row: These facilities were staffed to provide one-on-one
care for 14,644 women an average of 86.5% of the time. The provision of one-on-one
care to 14,644 women 100% of the time would be the functional equivalent of caring
for 16,930 patients 86.5% of the time, or an additional 2,286 patients. Given a mean
duration of oxytocin infusion of 8.5 h in our system, a 40-h work week for a registered
nurse full-time equivalent at 50 wk/y, and a mean hourly pay rate of $30 (chosen for
illustrative purposes only), such staffing would require an additional 9.7 full-time
equivalents and an additional salary cost of $582.930 annually.
Hospitals were categorized into quartiles according to frequency of 1:1 nursing (0–25%,
26–50%, 51–75%, > 75% of the time), and outcomes were compared between quartiles using
chi-square test for trends. A p < 0.05 was used to denote statistical significance. Because this study used only
deidentified aggregate data for quality improvement purposes, institutional review
board approval was not necessary.
Results
During 2010, 208,033 women delivered at an HCA-affiliated facility. Of these women
101,777 (49%) received oxytocin for labor induction or augmentation. [Table 1] demonstrates perinatal outcomes for each 1:1 nursing frequency quartile. [Table 2] demonstrates rates of birth asphyxia for each quartile. Primary cesarean delivery
rates and rates of overall complications increased significantly as the frequency
of 1:1 nurse staffing ratios increased. Lower rates of coded fetal distress were seen
with more consistent 1:1 staffing ratios ([Table 1]). There was no significant trend between staffing ratio and the rates of birth asphyxia
([Table 2]). Cost and staffing calculations for the model of universal 1:1 staffing are detailed
in [Table 3]. Compliance with a hypothetical model of universal 1:1 staffing for women undergoing
induction or augmentation of labor would necessitate an additional 1,618 full-time
labor and delivery nurse equivalents in the system of HCA affiliates, at an additional
cost of $97 million annually, using the assumptions outlined in [Table 3]. Extrapolation of these data to staffing throughout the United State would result
in the need for an additional 27,000 labor nurses at an additional cost of approximately
$1.6 billion annually.
Discussion
Careful nursing care is a vital component of modern obstetric management, not only
for women receiving oxytocin during labor, but for all women giving birth. Patient
safety may, in some cases, be enhanced by decreasing nurse-to-patient staffing ratios.
In fact, in a sufficiently large series we would expect to be able to identify some
statistical benefit to any cohort of laboring women receiving consistent 1:1 nurse-to-patient
staffing, as compared with a lower staffing ratio. Critical to such an analysis, however,
is the realization that in an era of limited medical resources and increasing demand
for services, medical expenditures of this type must be seen as a “zero sum” in which
a dollar spent in any one area of care is a dollar taken from another.[13]
[14] In a similar manner, the number of nurses in the United States cannot be readily
expanded indefinitely.[15]
[16] Under these circumstances, any new recommendation for care requiring significant
additional resources must be evidence-based, with the strength of evidence for benefit
directly proportional to the magnitude of proposed additional resource allocation.
In this large series of over 100,000 deliveries across a broad range of facilities
in the United States, we could demonstrate no meaningful positive clinical relationship
between staffing ratios and perinatal outcomes for women receiving oxytocin during
labor. Facilities that provided 1:1 staffing for these women < 25% of the time had
similar outcomes to those that provided such staffing > 75% of the time. The extremely
large numbers in our series did lead to a few differences that achieved statistical
significance in a trend analysis, suggesting a possible detrimental effect of higher staffing ratios. Higher staffing ratios were associated with more
cesarean deliveries and overall complications, but no difference in rates of birth
asphyxia, which along with cesarean rate would be the outcome of primary importance
with respect to oxytocin use during labor. Although from a statistical standpoint
one might conclude that a 1:1 staffing ratio was actually detrimental, because of
differences in patient acuity between facilities, we believe such clinical conclusions
are unjustified; it is also possible that those facilities with higher acuity appropriately
determined the need for more frequent 1:1 staffing ratios, and with the use of such
judgment achieved rates of birth asphyxia equivalent to those seen in facilities with
lower mean patient acuity. These data also do not suggest unwise resource utilization
for facilities that, because of typical patient acuity or nursing staff experience,
have decided to utilize universal 1:1 coverage for any class of patient. Rather, these
data support our current policy of allowing staffing decisions to be made for individual
patients by on-site clinicians, rather than mandating universal staffing ratios for
any broad group of patients.
Our interpretation of these findings involves the heterogeneity of individual patients
within the broad category of “received oxytocin during labor.” A woman with a category
I fetal heart rate tracing and a normally grown fetus beginning an induction at 41
weeks is in a risk category very different than a woman with known intrauterine growth
restriction, oligohydramnios, and variable decelerations receiving augmentation in
the active phase of labor. Yet both are receiving oxytocin. Further, a woman in the
next room with a bleeding placenta previa at 28 weeks may be in a risk category significantly
higher than either of these women. Under such circumstances, to mandate 1:1 nursing
for both of the first two patients in the face of limited nursing personnel may not
only be an inefficient use of resources, but may actually place the third patient
in significant jeopardy. Such variations and combinations are endless, yet they reflect
the realities of most labor and delivery services and will be recognized by individuals
actually providing clinical care. Under these conditions, arbitrary staffing rules
based on heterogeneous patient categories may negatively impact patient safety.
As outlined in [Table 3], we estimate that the universal national adoption of recommendations for mandatory
1:1 staffing ratios for all woman receiving oxytocin would cost the U.S. health care
system an additional $1.6 billion annually, assuming that an additional 29,000 labor
nurses could be found.
We acknowledge several limitations of the current study design. Outcomes data were
derived from an analysis of coded discharge diagnoses. Such analyses are commonly
relied upon in published series to identify various indices of neonatal and maternal
morbidity including birth asphyxia and neonatal encephalopathy.[17]
[18]
[19]
[20] Although such data have generally been found to be reasonably reliable in a variety
of clinical circumstances, the occurrence of occasional coding errors cannot be excluded.[17]
[18]
[19]
[20]
[21]
[22] However, the large sample size of our study population would tend to negate the
impact of random coding errors on our conclusions.
Given the current capabilities of our data system, several additional neonatal outcomes
of potential interest could not be analyzed on this scale and simultaneously linked
to maternal oxytocin administration. Our inability to control for differences in patient
acuity between facilities is another limitation, discussed at length previously. Finally,
our cost analysis represents only an estimate, as outlined in [Table 3].
In the past several years, HCA-affiliated facilities have broadly adopted patient
safety education and protocols directed at the safe use of oxytocin during labor.[1]
[2]
[3]
[4]
[5] Our results must be interpreted in this context—the overall commitment of these
facilities to the safe use of oxytocin may have rendered the staffing ratios for these
patients less relevant.
In conclusion, we could demonstrate no evidence of improved clinical outcomes associated
with the use of a 1:1 nursing ratio for women receiving oxytocin during labor. We
acknowledge the limitations of our data and the theoretical possibility that future
research using a more demographically detailed database might demonstrate a subgroup
of women for whom such uniform staffing ratios may be beneficial. However, the imperfections
of the current data must be viewed against a complete absence of any contradictory data demonstrating any clinical benefit of mandatory, universal
1:1 staffing ratios for women receiving oxytocin during labor. Further, our estimated
economic gap analysis clearly demonstrates the magnitude of the financial impact of
such recommendations, if implemented universally. Thus given our current state of
knowledge, evidence-based medicine suggests that it would be inappropriate and potentially
detrimental to patient safety to implement mandatory 1:1 staffing ratios for women
receiving oxytocin during labor at this time. The onus for demonstrating clinical
benefit, a favorable cost–benefit ratio, and an analysis of the impact of such recommendations
on those patients from whom vast resources would of necessity be diverted remains
with proponents of such rules.[23] Given the wide variability present in almost all categories of intrapartum patients,
we feel strongly that patient safety is best addressed by continuing to allow staffing
decisions to be made by qualified on-site nursing and medical personnel based on individual
patient acuity.
