What are some good pulse oximeters (pulse oxygen meters) for daily use in wards?

Pulse Oximeter Selection for Ward Use

For daily ward use, avoid cheap internet finger oximeters due to lack of validated accuracy, and instead procure hospital-grade devices from established manufacturers (Masimo, Nellcor, Philips, or Nihon Kohden) that have demonstrated reliable hypoxemia detection even during motion and low perfusion states.

Key Selection Criteria

Prioritize Validated Hospital-Grade Devices

• The BTS guidelines explicitly warn that many cheap, small finger oximeters available on the internet have not undergone thorough evaluation for accuracy and reliability 1.
• Despite this warning, these devices are being widely used by medical staff in many settings, but their performance remains unvalidated 1.
• Independent testing of four hospital-grade pulse oximeters (Masimo Radical-7, Nihon Kohden OxyPal Neo, Nellcor N-600, and Philips Intellivue MP5) demonstrated that all could detect clinically relevant hypoxemia during motion and low perfusion, though with varying degrees of accuracy 2.

Performance Under Real-World Ward Conditions

• Motion artifacts significantly degrade pulse oximeter performance: tapping, rubbing, and patient movement during activities like drinking or turning pages all increase measurement error (RMSE >4%) 2, 3.
• Three of four tested hospital-grade devices (Masimo, Nellcor, Philips) had root mean square error >3% during any motion, compared to 1.8% when stationary 2.
• The Nihon Kohden device showed better performance during low perfusion states compared to other manufacturers 2.
• All tested devices maintained ability to detect hypoxemia (SaO2 <90%) with sensitivity ≥0.87 and specificity ≥0.80 even during motion 3.

Specific Device Considerations

Finger-worn devices:

• Clip-on finger probes are easy to displace, producing artifactual data (under- or overestimation of oxygen saturation) 1.
• Proper probe positioning is critical for accurate readings 1.
• Newer pulse oximeters with motion-resistant algorithms are less susceptible to motion artifacts and may be more useful than older models 1.

Alternative monitoring sites:

• Ear lobe probes can serve as alternative sites when finger measurements are unreliable 4.
• Remove any jewelry and gently rub the lobe to improve local perfusion before measurement 4.

Essential Features for Ward Devices

Signal Quality Verification

• Always verify that the heart rate displayed on the pulse oximeter matches the ECG or palpated pulse rate—if these don't match closely, the reading is unreliable 4.
• Pulse oximeters have inherent accuracy limitations of ±4-5% even under optimal conditions 4.
• Accuracy is less reliable at saturations below 88%, particularly in patients with darker skin pigmentation 4.

Clinical Integration Requirements

• Pulse oximetry must be available in all locations where emergency oxygen is being used by healthcare professionals 1.
• The oximeter reading is now established as an essential part of the National Early Warning Score (NEWS) 1.
• Oxygen saturations should be considered the "fifth vital sign" 1.

Common Pitfalls and How to Avoid Them

Device Limitations to Recognize

• Standard two-wavelength pulse oximeters cannot distinguish carboxyhemoglobin (COHb) or methemoglobin (MetHb) because they use only two wavelengths of light 4.
• Dark skin pigmentation can interfere with signal detection and systematically overestimate oxygen saturation 4.
• Poor peripheral perfusion yields falsely low readings because adequate pulsatile flow is required for accurate measurement 4.
• Intravenously administered dyes (particularly methylene blue and indocyanine green) cause errors due to their absorbance properties 5.

When Pulse Oximetry is Insufficient

• Never rely solely on pulse oximetry when clinical assessment suggests respiratory compromise, especially in patients with known perfusion issues 4.
• If adequate signal cannot be obtained despite repositioning and alternative sites, obtain arterial blood gas analysis 4.
• Pulse oximetry does not provide information about adequacy of ventilation or precise arterial oxygenation when levels are very high or very low 6.
• Despite a fall in arterial PaO2 to 70 mmHg, saturation would still remain above 93% due to the oxygen dissociation curve characteristics 4.

Procurement Recommendations

Select devices from these validated manufacturers:

• Masimo (e.g., Radical-7 series) 2
• Nellcor (e.g., N-600 series) 2
• Philips (e.g., Intellivue series) 2
• Nihon Kohden (e.g., OxyPal Neo)—particularly for patients with anticipated low perfusion 2

Avoid:

• Unbranded internet finger oximeters without validation data 1
• Devices without motion-artifact reduction algorithms 1
• Single-use disposable devices for continuous ward monitoring (reserve these for infection control situations) 1