2.3 Patient Monitoring, Accessory Devices, Medications & Infection Control

Why This Matters

Items 11 through 14 close out Patient Assessment and Preparation with the "during and after" safety net: continuous monitoring, managing whatever tubes and lines the patient already has, reviewing and administering medications, and controlling infection risk. These items show up heavily in scenario questions about sedated pediatric patients, cardiac-gated CT, trauma patients arriving with lines already in place, and CT-guided procedures — anywhere the patient is higher-acuity than a routine outpatient scan.

Patient Monitoring

Item 11 lists six specific sub-areas, and each is independently testable.

ECG pattern monitoring deserves particular attention for CT-specific reasoning: during a coronary CT angiogram or calcium-scoring study, the scanner times image acquisition to the cardiac cycle using either prospective or retrospective gating. An irregular rhythm — a premature ventricular contraction or atrial fibrillation, for example — introduces motion and misregistration into the reconstructed images. The technologist who recognizes an arrhythmia on the monitor during setup may need to switch gating strategies, alert the ordering team about possible rate-control medication, or flag the study as technically limited, rather than simply proceeding as if the rhythm were regular.

Management of Accessory Medical Devices

Item 12 covers three specific device categories, each with its own handling rule:

• Oxygen delivery systems. Nasal cannula flow is typically 1–6 L/min; a non-rebreather mask with reservoir bag runs 10–15 L/min. Before transporting a patient on a portable tank, check the gauge pressure and calculate whether the remaining supply covers the full round trip away from the wall oxygen source, including any delay in the scan room.
• Chest tubes. Never clamp a chest tube without a physician's order — clamping a functioning tube risks a tension pneumothorax. Keep the collection unit below the level of the chest and upright to preserve the water seal, and watch for kinking or tension on the tubing during every transfer.
• Indwelling catheters. A Foley catheter's drainage bag must stay below the level of the bladder at all times to prevent retrograde urine flow and the associated urinary tract infection (UTI) risk. Central lines and peripherally inserted central catheters (PICC lines) require sterile technique at every connection, secured tubing during transfers to avoid dislodgement, and patency confirmation before any use for power-injected contrast (see Chapter 3).

Medications and Dosage

Item 13 has three parts. Current medications are reconciled at intake — anticoagulants, diabetes medications such as metformin, and rate-controlling beta-blockers all matter both for safety screening and, in the case of beta-blockers, for cardiac CT image quality. Preprocedure medications include a steroid premedication regimen for patients with a documented prior contrast reaction (the full protocol is covered in Chapter 3) and anti-anxiety premedication, such as a short-acting benzodiazepine, for claustrophobic patients — administered only per order and with appropriate monitoring afterward. Postprocedure instructions include encouraging hydration after iodinated contrast and giving diabetic patients on metformin guidance aligned with current ACR (American College of Radiology) and FDA (Food and Drug Administration) recommendations: metformin is held only when renal function is impaired, not as a universal rule for every contrast patient, and instructions given must be documented in the chart.

Infection Control

Item 14 is grounded in standard precautions — hand hygiene before and after every patient contact, and personal protective equipment (PPE) selected to match the exposure risk — plus equipment-specific cleaning rules captured by the Spaulding classification system:

Patients on transmission-based precautions (contact, droplet, or airborne isolation) require workflow adjustments: scheduling the patient last when feasible, donning the correct PPE before entering the room, and performing a terminal clean of the table, gantry, and any reusable positioning aids afterward. Sharps from venipuncture (Chapter 3) must go directly into a puncture-resistant container immediately after use as part of the department's bloodborne-pathogen exposure control plan.

Realistic Exam Scenario

A patient with a Foley catheter arrives for a trauma CT and must be moved from a stretcher to the CT table. The correct handling is to keep the drainage bag below the level of the bladder throughout the transfer, secure the tubing so it cannot be pulled taut or kinked, and never clamp or disconnect the line — clamping risks bladder distension and disconnecting breaks a closed, sterile drainage system and raises UTI risk.

Common Traps

• Assuming any chest tube can be clamped for a quick transfer — it cannot, without a physician's order, because of the tension pneumothorax risk.
• Treating metformin-hold instructions as a blanket rule for every contrast patient rather than a renal-function-dependent decision.
• Confusing noncritical equipment cleaning (a low-level wipe-down between patients, used for the table and gantry) with the critical sterilization standard required for anything that penetrates sterile tissue, such as a biopsy needle.