When considering the emergency medical services, there has been much discussion regarding the utility of advanced life support and its effectiveness within the emergency medical services (Stiell et al., 2005; Stiell et al., 2003; Stiell et al., 2002; Stiell et al., 1999). One of the most basic skills that paramedics use exclusively is intravenous cannulation and the subsequent delivery of isotonic intravenous fluid. Intravenous cannulation is one of the first advanced skills that paramedics utilize within the course of treatment as it allows to correct for shock, provides a means for administering parenteral medications, and provides a means for drawing blood for testing either in the field or upon arrival at the receiving emergency department. As the body’s stress increases when dehydration is present, it is imperative to correct dehydration during the course of treating most ailments; otherwise, the body’s own compensatory mechanisms can fail despite otherwise adequate treatment (Wakefield, Mentes, Holman, & Culp, 2008). Additionally, dehydration can mask some critical tests, such as other blood values and radiological findings (Hash, Stephens, Laurens, & Vogel, 2000).

Though the research is limited, it is also important to note that judicious use, or overuse, of intravenous fluids can be detrimental in some cases (Rotstein et al., 2008). In order to test the effectiveness of paramedic treatment of co-morbid dehydration, we can observe for fluid status before and after treatment as well as between those patients transported by paramedic ambulance as compared to patients who present to the emergency department by other means (e.g. basic life support ambulance, walk-in); however, it is first important to understand if those patients who present to the emergency department are, indeed, dehydrated.

In order to study if paramedics have an impact in treating co-morbid dehydration, there has to be an assumption that a) most people are not dehydrated and b) people who present to the emergency department (the dependent variable) are more dehydrated (independent variable) than most of the population. As we can never be sure of the hydration status of the entire population at any given time or the standard deviation of the entire population, we can use the normal mean blood urea nitrogen value of 10 mmol/L and assume a normal distribution (Hash et al., 2000).

H0:μ=10: Patients who present to the emergency department are not dehydrated (BUN = 10 mmol/L)

Ha:μ>10: Patients who present to the emergency department are dehydrated (BUN > 10 mmol/L)

Once the random sample of BUN values have been obtained, I can use the t-distribution to find the value of the t-test statistic:

t = (x̄ - μ) / (s / √n)

Next, I would compute the degrees of freedom (it is important to note that the sample size [n] must be greater than 30 as the standard deviation of the population is not known):

DOF = n - 1

As this test is one-tailed (specifically, right-tailed), and I am concerned with a 95% CI, I would compare the t-value with the t-table row indicated by the DOF. If the t-value is greater than the t-value corresponding with the DOF, then I will be able to reject the null hypothesis; otherwise, if the computed t-value is less than the table value, I will not be able to reject the null hypothesis.

References

Hash, R. B., Stephens, J. L., Laurens, M. B., & Vogel, R. L. (2000). The relationship between volume status, hydration, and radiographic findings in the diagnosis of community-acquired pneumonia. Journal of Family Practice, 49(9), 833-837.

Rotstein, C., Evans, G., Born, A., Grossman, R., Light, R. B., Magder, S., … & Zhanel, G. G. (2008). Clinical practice guidelines for hospital-acquired pneumonia and ventilator-associated pneumonia in adults. Canadian Journal of Infectious Diseases & Medical Microbiology, 19(1), 19–53.

Stiell, I. G., Nesbitt, L., Pickett, W., Brisson, D., Banek, J., Field, B, … & Wells, G., for the OPALS Study Group. (2005). OPALS Major Trauma Study: impact of advanced life support on survival and morbidity. Academy of Emergency Medicine, 12(5), 7.

Stiell, I. G., Nesbitt, L., Wells, G. A., Beaudoin, T., Spaite, D. W., Brisson, D., … & Cousineau, D., for the OPALS Study Group. (2003). Multicenter controlled trial to evaluate the impact of ALS on out-of-hospital chest pain patients. Academy of Emergency Medicine, 10(5), 501.

Stiell, I. G., Wells, G. A., Spaite, D. W., Nichol, G., Nesbitt, L., De Maio, V. J., … & Cousineau, D., for the OPALS Study Group. (2002). Multicenter controlled clinical trial to evaluate the impact of advanced life support on out-of-hospital respiratory distress patients. Academy of Emergency Medicine, 9(5), 357.

Stiell, I. G., Wells, G. A., Spaite, D. W., Nichol, G., O’Brien, B., Munkley, D. P., … & Anderson, S., for the OPALS Study Group. (1999). The Ontario Prehospital Advanced Life Support (OPALS) Study Part II: Rationale and methodology for trauma and respiratory distress patients. Annals of Emergency Medicine, 34, 256-262.

Wakefield, B. J., Mentes, J., Holman, J. E., & Culp, K. (2008). Risk factors and outcomes associated with hospital admission for dehydration. Rehabilitation Nursing, 33(6), 233-241. doi:10.1002/j.2048-7940.2008.tb00234.x