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

German S3 Guideline: Oxygen Therapy in the Acute Care of Adult Patients

BACKGROUND

Oxygen (O2) is a drug with specific biochemical and physiological properties, a range of effective doses and may have side effects. In 2015, 14% of over 55,000 hospital patients in the UK were using oxygen. 42% of patients received this supplemental oxygen without a valid prescription. Health care professionals are frequently uncertain about the relevance of hypoxemia and have low awareness about the risks of hyperoxemia. Numerous randomized controlled trials about targets of oxygen therapy have been published in recent years. A national guideline is urgently needed.

METHODS

A national S3 guideline was developed and published within the Program for National Disease Management Guidelines (AWMF) with participation of 10 medical associations. A literature search was performed until February 1, 2021, to answer 10 key questions. The Oxford Centre for Evidence-Based Medicine (CEBM) System ("The Oxford 2011 Levels of Evidence") was used to classify types of studies in terms of validity. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of evidence and for grading guideline recommendation, and a formal consensus-building process was performed.

RESULTS

The guideline includes 34 evidence-based recommendations about indications, prescription, monitoring and discontinuation of oxygen therapy in acute care. The main indication for O2 therapy is hypoxemia. In acute care both hypoxemia and hyperoxemia should be avoided. Hyperoxemia also seems to be associated with increased mortality, especially in patients with hypercapnia. The guideline provides recommended target oxygen saturation for acute medicine without differentiating between diagnoses. Target ranges for oxygen saturation are based depending on ventilation status risk for hypercapnia. The guideline provides an overview of available oxygen delivery systems and includes recommendations for their selection based on patient safety and comfort.

CONCLUSION

This is the first national guideline on the use of oxygen in acute care. It addresses health care professionals using oxygen in acute out-of-hospital and in-hospital settings.

[German S3 Guideline - Oxygen Therapy in the Acute Care of Adult Patients]

BACKGROUND

 Oxygen (O₂) is a drug with specific biochemical and physiologic properties, a range of effective doses and may have side effects. In 2015, 14 % of over 55 000 hospital patients in the UK were using oxygen. 42 % of patients received this supplemental oxygen without a valid prescription. Healthcare professionals are frequently uncertain about the relevance of hypoxemia and have low awareness about the risks of hyperoxemia. Numerous randomized controlled trials about targets of oxygen therapy have been published in recent years. A national guideline is urgently needed.

METHODS

 A S3-guideline was developed and published within the Program for National Disease Management Guidelines (AWMF) with participation of 10 medical associations. Literature search was performed until Feb 1st 2021 to answer 10 key questions. The Oxford Centre for Evidence-Based Medicine (CEBM) System ("The Oxford 2011 Levels of Evidence") was used to classify types of studies in terms of validity. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used and for assessing the quality of evidence and for grading guideline recommendation and a formal consensus-building process was performed.

RESULTS

 The guideline includes 34 evidence-based recommendations about indications, prescription, monitoring and discontinuation of oxygen therapy in acute care. The main indication for O₂ therapy is hypoxemia. In acute care both hypoxemia and hyperoxemia should be avoided. Hyperoxemia also seems to be associated with increased mortality, especially in patients with hypercapnia. The guideline provides recommended target oxygen saturation for acute medicine without differentiating between diagnoses. Target ranges for oxygen saturation are depending on ventilation status risk for hypercapnia. The guideline provides an overview of available oxygen delivery systems and includes recommendations for their selection based on patient safety and comfort.

CONCLUSION

 This is the first national guideline on the use of oxygen in acute care. It addresses healthcare professionals using oxygen in acute out-of-hospital and in-hospital settings. The guideline will be valid for 3 years until June 30, 2024.

Monitoring the injured patient

Monitoring of the injured patient is important. It includes clinical assessment, following the ABCDE approach, and the use of instruments found from the prehospital to critical care setting.

Correctly used, these provide important information about the patient's current physiological state and response to treatment plus diagnostic and prognostic implications that are useful to the clinician involved in the care of injured patients.

Pulse oximetry in clinical forensic practice

The potential role of a hand held battery operated digital pulse oximeter was investigated on 270 consecutive patients seen by one forensic medical examiner. An oxygen saturation reading on air was obtained on 236 patients (87%). Of the patients in whom the pulse oximeter could not provide a reading, the principal reason for being unable to record a value was lack of patient cooperation (26 of the 34 patients). Of the 236 oxygen saturations recorded, 234 were 95% or higher. The two patients with lower readings (83% and 93%) required assessment and treatment at hospital: one for an opioid overdose, the other for pneumonia. The modern generation of hand held pulse oximeters can provide very useful information in a challenging environment and should occupy a definite corner of the forensic medical examiner's medical bag.

Influence of Positive End-Expiratory Pressure Ventilation on Survival During Severe Hemorrhagic Shock

STUDY OBJECTIVE

Although a moderate positive end-expiratory pressure (PEEP) level is widely recommended, it is unknown whether moderate PEEP during mechanical ventilation has adverse effects during severe hemorrhagic shock. Therefore, the purpose of our study was to evaluate the effects of 0 cm H2O PEEP versus 5 cm H2O PEEP versus 10 cm H2O PEEP on short-term survival in a porcine model of severe hemorrhagic shock. Secondary study endpoints were hemodynamic variables and blood gases.

METHODS

Twenty-four anesthetized pigs were bled approximately 45 mL/kg, randomized into 3 groups, and then ventilated with 0, 5, or 10 cm H2O PEEP. Survival rates were compared using Kaplan-Meier methods with log rank (Mantel Cox) comparison of cumulative survival by treatment group.

RESULTS

Seven of 8 0 cm H2O PEEP animals survived the 120-minute study period, but 8 of 8 5 cm H2O PEEP animals died within 30 minutes, and 8 of 8 10 cm H2O PEEP animals were dead within 20 minutes (P<.0001). Ventilation with 0 cm H2O PEEP prevented a further reduction of mean arterial blood pressure and cardiac output. When compared with the 0 cm H2O PEEP group, end-tidal CO2 declined in the 5 cm H2O PEEP and 10 cm H2O PEEP animals. Compared with the 0 cm H2O PEEP animals, those ventilated with 5 or 10 cm H2O PEEP had higher lactate levels after 10 minutes.

CONCLUSION

When compared with pigs ventilated with either 5 or 10 cm H2O PEEP, those ventilated with 0 cm H2O PEEP during untreated, severe hemorrhagic shock had significantly improved short-term survival.

Capnography in Non-Tracheally Intubated Emergency Patients as an Additional Tool in Pulse Oximetry for Prehospital Monitoring of Respiration

Victims of minor trauma transported by paramedic-based rescue systems are usually monitored with pulse oximetry. Under the difficult surroundings of prehospital trauma care, pulse oximeters show considerable periods of malfunction. We tested the hypothesis that capnography is a good, easy to use tool for monitoring in nonintubated trauma victims. Seventy nonintubated trauma victims were included in this study. Vital variables and number and time of malfunctions were sampled for oximeter and capnometer recordings. Total number of alerts (63 versus 10), number of alerts per patient (3.3 [1.9] versus 0.3 [0.9]) (mean [SD]), total time of malfunction (191.5 [216.7] s versus 11.8 [40.2] s), time of malfunction per alarm (58.3 [71.4] s versus 5.5 [14.6] s), and the percentage of malfunction time during transport (13.2% [15.3%] versus 0.8% [2.8%]) differed significantly (P < 0.01) between oximetry and capnography. Although pulse oximetry is a standard method of monitoring in emergency care, we found capnography to be helpful as a monitoring device. We consequently recommend the use of capnography on transport as an additional monitoring tool to reduce periods lacking supervision of the vital variables.

IMPLICATIONS

Capnography is a useful tool to improve respiratory monitoring in nonintubated trauma victims on emergency transport and an easy to use supplement to pulse oximetry.

Effect of routine pulse oximetry measurements on ED triage classification

Pulse oximetry is commonly used to rapidly determine oxygen saturation and is incorporated in emergency triage as a screening for potential cardiopulmonary complications. This study examined the effect of routine pulse oximetry measurements on emergency department (ED) triage classification. Using a portable pulse oximeter, oxygen saturation of 1,235 adults presenting to a university-based, urban ED was obtained and each patient was assigned a classification of severity based on a standard 1-to-4 scale before and after the measurement. According to data obtained, a small but statistically significant group (2.8%) benefitted from the routine use of pulse oximetry in an emergency triage system and only 40% of these patients required admission or extended care. Although this group is small in number, the potential consequences of missing a hypoxic condition could be devastating for the individual patient. Since pulse oximetry is presently an inexpensive technology, it would seem to be a worthwhile screening tool for emergency triage.