Ambient Temperature on Patients

EFFECTS OF AMBIENT TEMPERATURE ON PATIENT TEMPERATURE IN WARM WEATHER CONDITIONS DURING ROTOR WING AIR AMBULANCE TRANSPORT

Robbie Covert RN PhD
Kelly Cox MD FACEP

ABSTRACT

Aim: To evaluate the effects of ambient temperature on patient temperature during rotor wing air ambulance transport.

Methods: This retrospective observational review was conducted by Air Evac EMS, Inc in the Bell 206 rotor-wing air ambulance.7122 patient flights noted from May 2008 to September 2008 comprised this study. The ambient cabin temperature and the patient’s temperature were recorded at the time of liftoff, midpoint of the flight and again at the time of landing. The data analyzed included all data with an ambient cabin temperature less than 90 degrees Fahrenheit and an ambient cabin temperature greater than 90 degrees Fahrenheit. A comparison of means was performed with a t-test

Results: Of the 6931 cases with a cabin temperature reported less than 90 degrees Fahrenheit; there was no significant difference in patient temperature from liftoff and landing. Of the 191 cases with a cabin temperature reported as greater than 90 degrees Fahrenheit, there was no significant difference in patient temperature from liftoff and landing.

Conclusions: The review demonstrates that an ambient cabin temperature less than 90 degrees Fahrenheit and an ambient cabin temperature greater than 90 degrees Fahrenheit creates no significant difference in patient temperature during transport.

METHODS

Review and Design Setting

Data was collected from bases in the states of Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Mississippi, Missouri, Oklahoma, Tennessee and Texas.
The regional temperatures vary in the months May, June, July, August and September for each area. The mean temperature by month for each state is summarized in table 1.

Table 1 Mean temperatures by month in states services provided 1

Data collection and processing

The data was collected from 7122 patient flights whereby 6931 charts documenting an ambient cabin temperature less than 90 degrees Fahrenheit plus 191 charts documenting an ambient cabin temperature greater than 90 degrees Fahrenheit. The patient temperature and cabin temperature is reflectively noted upon liftoff, midpoint of the flight and upon landing. The institutional policy requires every effort will be made to keep the aircraft cabin temperature less than 90 degrees Fahrenheit through measures of shading, window and vent openings and altitudes that allow for temperature reduction if possible. Furthermore, the patient will be packaged in a manner consistent with maintaining normal body temperature during exposure to excessively high and low temperatures.

Primary data analysis

Statistical analysis was performed with SPSS software for Windows, version 15 (SPSS, Inc, Chicago, Illinois, USA) Frequency and distribution analysis were used to describe the associations between the beginning and end temperature. The data was evaluated as a subgroup of ambient cabin temperature less than 90 degrees Fahrenheit and cabin temperature greater than 90 degrees Fahrenheit. A t-test for paired samples compared the relationship between the beginning and end temperature in all groups. A two-tailed p-value of <0.01 was considered significant.

RESULTS

During the review period of 153 days, the descriptive statistics for the lifting and landing temperatures of the 6931 patients transported with an ambient cabin temperature less than 90 degrees Fahrenheit are summarized in table 2.

Table 2.  
                                                                 Descriptive Statistics

On paired t-test analysis, there was no significant difference between lifting and landing patient temperature. The paired samples correlation is shown in table 3.

Table 3

                                                 Paired Samples Statistics

                                           Paired Samples Correlations

In that same period of time 191 patients were transported with an ambient cabin temperature greater than 90 degrees Fahrenheit. The descriptive statistics for that subgroup are summarized in table 4.

Table 4

                                                                 Descriptive Statistics

On paired t-test analysis, there was no significant difference between lifting and landing patient temperature. The paired samples correlation is shown in table 5.

Table 5           

                                                  Paired Samples Statistics

                                           Paired Samples Correlations

DISCUSSION

This chart review demonstrates that in the sample of 6931 patients with transported with an ambient cabin temperature less than 90 degrees Fahrenheit there was no significant difference in the paired samples correlation between beginning and end patient temperature during transport. Furthermore, in the sample of 191 patients with an ambient cabin temperature greater than 90 degrees Fahrenheit there was no significant difference in the paired samples correlation between beginning and end patient temperatures during transport. 

The highest ending temperature reported was 101 degrees Fahrenheit in both groups. In the sample of 6931 patients transported with an ambient cabin temperature less than 90 degrees Fahrenheit;

• 91 patients had a documented ending temperature of 101 degrees Fahrenheit.
• Of those 91 patients, 65 presented with an initial temperature of 101 degrees Fahrenheit.
• Twelve presented with an initial temperature of 100.0 to 100.8 degrees Fahrenheit,
• Ten presented with an initial temperature of 99 to 99.8 degrees Fahrenheit.
• Four presented with an initial temperature of 99.8 degrees Fahrenheit. All four of those cases had neurological issues to include a seizure, a CVA, an overdose, and a pediatric case of seizures with a co-morbidity of Spina Bifida.
• 56 cases of patients with a lifting temperature of 101 degrees Fahrenheit experienced a drop in temperature at the time of landing.

In the 191 cases with a reported cabin temperature of greater than 90 degrees Fahrenheit;

• Five cases reported a landing temperature of 101 degrees Fahrenheit. All five cases began with an initial temperature of 101 degrees Fahrenheit.
• Six cases of patients with a lifting temperature of 101 degrees Fahrenheit experienced a drop in temperature at the time of landing.

The case report with the greatest increase in temperature was in a case with a documented cabin temperature greater than 90 degrees Fahrenheit. In this case the patient temperature increased by 2.4 degrees Fahrenheit during a 26 minute flight. The lifting temperature was documented at 97 degrees Fahrenheit, the mid-flight temperature was documented at 98.6 degrees Fahrenheit and the landing temperature was documented at 99.4 degrees Fahrenheit. The documented high temperature for the destination was 98 degrees Fahrenheit on the day of transport.2 the transport occurred between 12:51 and 13:17 hours. The patient diagnosis was cardio-pulmonary arrest.

CONCLUSIONS:

In summary, this review demonstrates there is no significant change in patient temperature during transport in relation to the aircraft cabin temperature when the ambient cabin temperature is less than 90 degrees Fahrenheit or when the cabin temperature is greater than 90 degrees Fahrenheit.

REFERENCES

http://countrystudies.us/united-states/weather; accessed September 26, 2008
http://www.wunderground.com/weatherstation, accessed September