A comparison of pulse oximeters during helicopter flight

Noninvasive Monitoring during Interhospital Transport of Newborn Infants

The main indications for interhospital neonatal transports are radiographic studies (e.g., magnet resonance imaging) and surgical interventions. Specialized neonatal transport teams need to be skilled in patient care, communication, and equipment management and extensively trained in resuscitation, stabilization, and transport of critically ill infants. However, there is increasing evidence that clinical assessment of heart rate, color, or chest wall movements is imprecise and can be misleading even in experienced hands. The aim of the paper was to review the current evidence on clinical monitoring equipment during interhospital neonatal transport.

The provision of sophisticated critical care beyond the hospital: Lessons from physiology and military experiences that apply to civil disaster medical response

OBJECTIVE

The provision of sophisticated medical care in an austere environment is challenging. During and after a mass casualty event, it is likely that critical care services will be needed beyond an intensive care unit (ICU) setting. The objective of this article is to explore existing ICU care systems such as military aeromedical transport that may be applicable to disaster medicine and to providing critical care outside of an ICU setting.

RESULTS

The U.S. Air Force Critical Care Aeromedical Transport (CCAT) Teams were developed in 1994 in response to an unmet military need for long-range air transport of critically ill and injured patients. This system has transported several thousand ICU patients and is an applicable model for the future development of extrahospital critical care capabilities needed during a disaster. We also discuss civilian aeromedical critical care systems, the types of medical devices used, and their applicability to disaster medical response.

CONCLUSION

The U.S. Air Force CCAT Team program, as well as many civilian critical care air ambulance services, provides a workable starting point for the development of disaster medical critical care response capabilities for disaster medical systems.

Pulse oximetry: principles and limitations

The pulse oximeter has become an essential tool in the modern practice of emergency medicine. However, despite the reliance placed on the information this monitor offers, the underlying principles and associated limitations of pulse oximetry are poorly understood by medical practitioners. This article reviews the principles of pulse oximetry, with an eye toward recognizing the limitations of this tool. Among these are performance limitations in the settings of carboxyhemoglobinemia, methemoglobinemia, motion artifact, hypotension, vasoconstriction, and anemia. The accuracy of pulse oximetry is discussed in light of these factors, with further discussion of applications for pulse oximetry in emergency medicine, including both oximetric and plethysmographic operation. The pulse oximeter is an invaluable instrument for emergency medicine practice, but as with any test the data it offers must be critically appraised for proper interpretation and utilization.

Can prehospital personnel detect hypoxemia without the aid of pulse oximeters?

Although pulse oximeters have been proven accurate in the prehospital environment, they have not been proven to be necessary. This study was undertaken to determine if emergency medical services (EMS) providers can identify hypoxemia without pulse oximetry. An oximeter was placed at the ambulance entrance to the emergency department (ED), and EMS personnel obtained saturation levels on all patients on arrival. Hypoxemia was defined as a saturation level of 95% or less. The hypoxemia was classified as "recognized" if the patient received aggressive intervention and "unrecognized" if the patient did not. One hundred eighty patients were enrolled in the study; 30 had a saturation level of 95% or less. Twenty-seven (90%) of those patients had "unrecognized" hypoxemia. Twenty-three (85.2%) of the 27 patients with "unrecognized" hypoxemia did not complain of respiratory distress. Thus, there are patients whose hypoxemia is unrecognized by EMS providers, and this occurs most frequently in patients who do not complain of respiratory distress.

Influence of the helicopter environment on patient care capabilities: flight crew perceptions

INTRODUCTION

Flight crew perceptions of the effect of the rotary-wing environment on patient-care capabilities have not been subject to statistical analysis. We hypothesized that flight crew members perceived significant difficulties in performing patient-care tasks during air medical transport.

METHODS

A survey was distributed to a convenience sample of flight crew members from 20 flight programs. Respondents were asked to compare the difficulty of performing patient-care tasks in rotary-wing and standard (emergency department or intensive care unit) settings. Demographic data collected on respondents included years of flight experience, flights per month, crew duty position and primary aircraft in which the respondent worked. Statistical analysis was performed as appropriate using Student's t-test, type III sum of squares, and analysis of variance. Alpha was defined as p < 0.05.

RESULTS

Fifty-five percent of programs (90 individuals) responded. All tasks were significantly rated more difficult in the rotary-wing environment. Ratings were not significantly correlated with flight experience, duty position, flights per month or aircraft used.

CONCLUSIONS

We conclude that the performance of patient-care tasks are perceived by air medical flight crew to be significantly more difficult during rotary-wing air medical transport than in hospital settings.

Prehospital pulse oximetry: useful or misused?

STUDY OBJECTIVE

This study evaluated the ability of emergency medical technicians (EMT-As) and emergency medical technicians-paramedics (EMT-Ps) to use pulse oximetry measurements in determining patient oxygen requirements.

DESIGN

Prospective case series.

SETTING

Cleveland emergency medical services (EMS) system.

TYPE OF PARTICIPANTS

Five hundred thirty-two consecutive patients transported to Cleveland area hospitals by the Cleveland EMS system; no exclusions.

INTERVENTIONS

EMT-Ps and EMT-As predicted patients' supplemental oxygen requirements based on clinical assessment. Pulse oximetry was performed while patients were breathing room air (RA SpO2). Treatment intervention, including oxygen supplementation and medication given, oxygen saturation after intervention, and oxygen saturation on arrival at the hospital, was also recorded. Therapy guided by the patient's initial RA SpO2 was reviewed to determine the appropriateness of oxygen therapy.

RESULTS

Data were analyzed using the chi 2 test and correlation analysis. Eleven percent (59) of patients transported by Cleveland EMS had an initial RA SpO2 of less than 91%. Advanced life support units increased oxygen supplementation on all desaturated patients, whereas basic life support units failed to make appropriate increases in FIO2 in 20% (two) of desaturated patients (P less than .0001). Sixty percent (164) of patients transported by EMT-Ps and 62% (162) of patients transported by EMT-As had an initial RA SpO2 of 97% or greater. EMT-Ps gave supplemental oxygen therapy to all but 7% (11) of these already well-saturated patients, and EMT-As gave supplemental oxygen to all but 6% (nine) of these patients. EMT-Ps administered a higher FIO2 than they had predicted clinically necessary to 2% (four) of patients with an initial RA SpO2 of 97% of greater, whereas EMT-As gave a higher FIO2 than initially predicted to 16% (25) of such patients (P less than .0001).

CONCLUSION

EMT-Ps were more likely to appropriately base oxygen therapy on oximetry measurements than were EMT-As. Both groups failed to decrease supplemental oxygen in patients with high explicit protocols for EMS systems contemplating the use of oximetry to guide oxygen therapy. Our results further suggest that pulse oximetry could be used to avoid unnecessary oxygen therapy on a significant number of patients transported by EMS systems because they are already well saturated on room air.

An evaluation of pulse oximetry in prehospital care

STUDY OBJECTIVES

We performed this study to evaluate the accuracy of pulse oximetry oxygen saturation (SpO2) against direct measurements of arterial oxygen saturation (SaO2) in the field.

DESIGN

Prospective, cross-sectional, paired measurements of SpO2 against SaO2.

SETTING

This evaluation was done in the prehospital setting.

INTERVENTIONS

A pulse oximeter with digital probe was used to measure SpO2 in 30 patients. Arterial blood gases were drawn in the field while the pulse oximeter was in use, and oxygen saturation (HbO2) was measured by CO-oximetry.

MAIN RESULTS

There was no significant difference between SpO2 (94.6 +/- 5.4%) and HbO2 (94.9 +/- 5.1%) (P = .495, beta less than .2). There was a strong correlation between SpO2 and HbO2 (r = .898). The bias between SpO2 and HbO2 was -0.3, with a precision of 2.4. When SpO2 was 88% or more, HbO2 was 90% or more in every case. Mean carboxyhemoglobin was 1.3 +/- 0.9%, and mean methemoglobin was 0.9 +/- 0.3%. There was no significant difference between the pulse oximeter heart rate and the ECG heart rate (P = .223, beta less than .2).

CONCLUSION

We conclude that pulse oximetry is sufficiently accurate to be useful in the field when SpO2 is more than 88%. It is potentially useful in patients with clinical signs of acute hypoxemia and in patients receiving interventions that may produce acute hypoxemia. Further work is needed to evaluate the accuracy of pulse oximetry in the settings of elevated carboxyhemoglobin, methemoglobin, and very low saturations.

Biomedical technology: using it during patient transport

The purpose of this article has been to discuss and present some of the current biomedical technology available for patient transport. Recommendations were offered concerning the evaluation of these products, so that they can be effectively used in the air medical environment. There is one step yet that needs to be taken. This step involves identifying the most appropriate application of this technology to the care of the patient. As asked at the beginning of this article, how many pumps and monitors are needed for safe and high-quality patient transport? The answer to that question is not within the scope of this article, but pieces to the answer are. Through research, those of us who provide care during transport should be able to answer this question and develop guidelines for the use of biomedical technology when caring for the patient during air medical transport.