Blood Gas Analyzer Setup: QC, Sample Mode & Bedside ABG Workflow

Blood gas analyzer setup is the nursing and point-of-care workflow that makes a bedside or unit-based analyser ready to accept a specimen: power-up and self-test, electrode or cartridge checks, calibration and quality control (QC), correct patient demographics, appropriate sample-type selection, and safe handling of the syringe arriving from arterial blood gas (ABG) sampling or an arterial line draw.

The analyser measures values such as pH, PaCO₂, and PaO₂ (when arterial) that guide oxygen therapy, ventilation changes, and escalation in COPD, asthma, pneumonia, diabetic ketoacidosis, and sepsis. Nurses use it when clinicians need objective gas exchange and acid–base data beyond pulse oximetry or capnography—for example when shortness of breath, hypoxia symptoms, or central cyanosis do not match the monitor. Formal interpretation of results is described on the arterial blood gas test page; this guide focuses on safe setup and specimen handling.

Point-of-care analysers fail quietly when QC is skipped. Treat startup prompts as mandatory—not optional—before patient specimens.

• Power-on self-test: Allow warm-up per manufacturer instructions for use (IFU); note error codes on the display and resolve before patient testing.
• Calibration: Run automatic or manual calibration when the device requests it; do not analyse patient samples during a failed calibration cycle.
• QC solutions: Complete required control levels (e.g. normal and abnormal ranges) per laboratory policy and log lot numbers, expiry, and operator ID.
• Cartridges / electrodes: Check expiry dates, installation integrity, and remaining test counts; replace when the analyser flags depletion or date expiry.
• Between patients: Wipe external surfaces and sample ports per IFU; perform hand hygiene before and after contact with blood specimens.

Selecting the wrong sample type on the analyser is a common source of misleading PaO₂ values. Match the mode to the order and specimen source.

When the clinical question is hypoxaemia or CO₂ retention, ensure sampling was arterial and that respiratory assessment and oxygen therapy documentation align with the gas result.

Most “unexpected ABG” calls trace to the syringe, not the patient. Inspect every specimen at the analyser.

• Ordered arterial blood gas after acute respiratory deterioration or peri-arrest care
• Monitoring response to oxygen or ventilator changes when SpO₂ alone is insufficient
• Acid–base assessment in metabolic emergencies such as DKA alongside electrolyte panels when the device provides them
• Post-procedure or post-extubation checks per critical care protocol
• Serial gases during non-invasive or invasive ventilation weaning when prescribed

• Failed QC or calibration lockout on the analyser
• Expired cartridge, electrode, or control solution
• Unidentified or mismatched patient/specimen label
• Specimen with visible clots, large bubbles, or obvious haemolysis when policy requires recollection
• Operator without documented competency on that device model

Deferring analysis is safer than publishing a result that cannot be traced or trusted. Obtain medical review when collateral circulation was abnormal before radial sampling and a repeat draw is being considered.

1. Verify order and indication — confirm the test is still required if the patient’s status changed after sampling.
2. Identify patient — use two identifiers and match the syringe label to the analyser screen.
3. Record oxygen therapy — device, flow rate, FiO₂, or ventilator settings; these must travel with the result.
4. Inspect specimen — bubble-free, adequate volume, correct cap, no leaks.
5. Complete QC if due — before patient specimen, not after a questionable result.
6. Hand hygiene and PPE — gloves when handling blood; follow hand hygiene standards after removal.

1. Power on and review status — confirm no outstanding errors; complete calibration/QC prompts.
2. Enter patient demographics — scan wristband; verify date of birth and hospital number match the syringe.
3. Select sample type — arterial vs venous/mixed per order; enter specimen source (radial, line, etc.) when the device allows.
4. Mix gently — roll syringe between palms to homogenize heparin; avoid vigorous shaking that introduces bubbles.
5. Expel air bubbles — per IFU, waste minimal volume if required to clear air from the sample path.
6. Aspirate or dock sample — follow device-specific technique until the analyser confirms adequate volume.
7. Wait for analysis — remain with the device until completion; do not leave an unattended open specimen.
8. Review flags — note hemolysis, clot, or temperature correction icons on the printout.
9. Print or upload results — attach to the chart per EHR policy; retain labels for audit if required.

Sterility checkpoint: If blood contacts the analyser housing, clean per IFU before the next patient and document any device contamination event per laboratory policy.

Thresholds vary by institution. Nurses do not independently reinterpret acid–base disorders, but must recognize analyzer-flagged critical results and close the communication loop.

• Read the institution’s critical ABG/pH/potassium limits posted at the analyser or in the EHR.
• Notify the responsible clinician immediately using the unit’s closed-loop process (read-back when possible).
• Document who was contacted, time, and repeat assessment plan (e.g. repeat gas, ECG, sepsis screening).
• Continue bedside monitoring: work of breathing, SpO₂, mental status, perfusion.
• Activate rapid response when the patient is deteriorating regardless of whether the full printout is yet in the chart.

• Dispose of syringe and needles in sharps container; never recap needles.
• Clean analyser sample port and work surface per IFU.
• Reassess puncture site or arterial line dressing if sampling was recent—pressure, perfusion, pain.
• Trend results with prior gases and clinical response after oxygen or ventilator changes.
• Store QC logs and operator records as required for accreditation audits.

Record objective data nurses own at the analyser:

• Date, time, operator ID, device identifier
• Specimen source (radial artery, arterial line) and sample type selected
• Oxygen/ventilator settings at time of draw
• QC performance when applicable (lot, pass/fail)
• Critical value notifications with clinician name and read-back if used
• Repeat sampling orders and patient tolerance

Example note: “22/05/2026 11:40 — ABG analysed on POC device #3 after QC pass. Arterial radial specimen; patient on 40% Venturi mask. Results uploaded; Dr. Patel notified for pH 7.18 flag at 11:42. Repeat ABG in 30 min ordered. Distal perfusion intact post-draw.”

• False hyperoxia from air bubbles or wrong sample mode
• False normoxia/hypoxia from venous sample labelled as arterial
• Shifted CO₂ from delayed analysis or improper mixing
• Altered potassium with hemolysis
• Patient harm from wrong chart when identifiers are not matched

• Critical or unexpected analyzer flags before results are filed
• Repeated QC or calibration failure on the only available device
• Cannot verify patient identity on the syringe
• Clinical deterioration despite a “normal” gas—treat the patient, not the printout alone
• Complications at the puncture site after sampling (hematoma, absent pulse, severe pain)

• Run QC at the start of the shift—not only after a questionable patient result.
• Keep the IFU QR code or quick-reference card at the analyser; models differ on mixing and waste volume.
• Phrase handoffs as data plus context: “ABG on 2 L/min NC, radial sample, analyzer flag low pH.”
• If SpO₂ and PaO₂ disagree, troubleshoot pre-analytic error before assuming the patient is fine.
• Never leave a labeled syringe on the counter—analyse or refrigerate per policy immediately.

When a syringe reaches the POC bench, pre-analytic choices decide whether ventilation changes are safe—rehearse NCLEX-style clinical judgment practice here with priority action, select-all-that-apply setup checks, delayed-specimen trend interpretation, matrix escalation, and documentation cloze focused on blood gas analyzer setup, QC, sample mode, and critical-value handoff.

About the author: Sid A. Abdala Balal, RN, writes evidence-based nursing education focused on practical bedside skills, patient safety, and clinical decision support for nurses.

Medical review: This guide is reviewed by Dr. Adam Sayedi for clinical accuracy, clarity, and alignment with current point-of-care blood gas testing, specimen-handling, and critical-value communication standards.

Policies: Medical Review Process · Editorial Policy · Correction Policy