Trends in Vital Signs in Relation to Patient Outcomes during Induction Phase in Treatment of Acute Leukemia

Introduction

Windsor Regional Hospital (WRH) treats approximately 17 patients per year with acute myeloid leukemia (AML). During the induction phase, patients remain at WRH for about four weeks. While hospitalized, patients are monitored and vitals are taken every 4-12 hours. Despite this, mortality in patients treated for acute leukemia is as high as 60% depending on patient factors and diagnosis (Garcia et al., 2013).

Hypothesis and Rationale

Studies have shown that patients with AML who are admitted to the intensive care unit (ICU) earlier have better outcomes than those admitted later (Lengliné et al., 2012). The correlation between patient's vitals and ICU admission would show if better patient outcomes could result from more frequent monitoring. Data and results will be used in a pilot project testing wireless outpatient monitoring technology for patients with acute leukemia.

Methods

A retrospective chart review was conducted of patients diagnosed with AML during 2015 - 2017. Patients were included in the ICU group if they were admitted to the ICU during induction chemotherapy and excluded if they were admitted to the ICU prior to induction. The control group consisted of patients who had undergone induction and were not admitted to the ICU.

Data Analysis

Vital signs were analyzed over the 24 hours prior to ICU admission for the ICU group, and over the 24 hour period 5 days post-induction chemotherapy for the control group. This time period was chosen as it was the average number of days post-chemotherapy that patients were admitted to the ICU. An unpaired T-test was done to compare the number of vitals recorded in the 24 hour period between both groups, and a one-way ANOVA was done to compare the proportion of missed vitals within the ICU group.

Results

Sample size of ICU group, n=7. Mean age at diagnosis = 51. Sample size of Control group, n=30. Mean age at diagnosis = 63. Statistically there was no difference in age between the two groups.

During the 24 hours prior to ICU admission, respiratory rate (RR) and fraction of inspired oxygen (FiO₂) demonstrated the greatest changes in patients compared to temperature (T), blood pressure (BP), heart rate (HR) and oxygen saturation (O₂Sat).

The average number of vitals taken in the 24 hours prior to ICU admission was 8.86. The average number of vitals taken in a 24 hour period five days post-induction chemotherapy in control patients was 2.67. No significant differences in number of vital signs were observed between the groups during these periods when compared using a two-tailed T-test assuming unequal variances (p=0.07).

Isolated missed vital signs were recorded as a percentage of total vital signs taken in the 24 hours prior to ICU admission. Average percentage of missed vital signs are as follows: T, 43.6%, BP, 16.8%, RR, 30%, HR, 19.3%, O₂Sat, 15.2%.

Reasons for ICU admission were recorded and the results were as follows: 85.71% respiratory issues, 57.14% infection, 14.29% cardiac issues and 14.29% nephrology issues.

Discussion

In the 24 hours prior to ICU admission, T, HR and BP did not significantly change in patients. Therefore, changes in these vital signs may not accurately predict if an AML patient will be admitted to the ICU. In the same patients, an increase in RR and, particularly, FiO₂, often occurred in the 24 hours prior to admission. This suggests an increase in RR or FiO₂ may be predictive of ICU admission during induction chemotherapy.

The average number of vital signs taken was not significantly different between the ICU and control groups. However, this could have been due to small sample size of the ICU group resulting in a large variance between the patients.

Although the difference was not statistically significant, RR was recorded the least in the 24 hours prior to ICU admission when compared to HR, BP and O₂Sat. T was excluded as it is not recorded on ICU consults. Recording RR more often may be able to better help health teams recognize which patients need to be admitted to the ICU and admit them promptly which will lead to improved survival.

Reason for ICU admission was predominantly related to respiratory failure, highlighting the need for increased measurement of related vital signs such as RR and O₂Sat.

Conclusion

RR and FiO₂ demonstrated the greatest changes in the 24 hours prior to a patient with acute leukemia being admitted to the ICU. Therefore, greater attention needs to be taken to monitor this parameter both in the inpatient setting and the outpatient setting.

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