Procedure Quick Cards

Quick-reference cards for common bedside procedures. See Resources by Technique for NEJM Videos and other multimedia guides.

Central Line (CVC)

Site Selection

Site	Depth	Key Advantages	Key Risks
Right IJ	~13 cm (or height / 10)	Best for ultrasound, compressible, lowest pneumothorax	Higher infection than subclavian per 3SITES
Left IJ	~15 cm	Same advantages as right IJ	Pleural dome higher on left
Subclavian	~15 cm right, ~17 cm left	Lowest infection rate (3SITES trial)	Highest pneumothorax risk; contraindicated with ipsilateral clavicle fracture
Femoral	~20-24 cm	Compressible, preferred in coagulopathy	Higher infection historically (3SITES showed similar to IJ); avoid if groin infection

Catheter Sizes

Catheter	French Size	Lumens	Typical Flow	Notes
Triple-lumen	7 Fr	3 (16 ga, 18 ga, 18 ga)	Standard	Most common CVC
Sheath introducer (Cordis)	8.5 Fr	1 (plus sideport)	~7.6 L/hr (20 L/hr with pressure bag)	Fastest non-HD option; for rapid transfusion or PA catheter
Dialysis catheter	11.5-12 Fr	2	High-flow	For CRRT or HD

Sterile Bundle Checklist

• Cap, mask, sterile gown, sterile gloves
• Chlorhexidine skin prep (allow to dry fully)
• Full-body sterile drape
• Ultrasound probe cover (sterile)
• 1% lidocaine for local anesthesia
• Guidewire, dilator, catheter, suture
• Saline-flush all ports
• Verify guidewire exits distal port before dilating
• Confirm venous placement (manometry, waveform, or blood gas) before dilating

Contraindications

• Absolute: Infection over site, anatomic obstruction (thrombosis)
• Relative: Coagulopathy — use compressible site (femoral greater than IJ greater than subclavian). No evidence for prophylactic FFP unless hemophilia or frank arterial puncture

Complications

Complication	Highest Risk Site	Mitigation
Pneumothorax	Subclavian	Ultrasound guidance; use IJ in ventilated patients
Arterial puncture	Femoral	Ultrasound guidance; confirm with manometry
Catheter-related bloodstream infection	Femoral (historical)	Maximal sterile barrier; remove when no longer needed
Air embolism	Any	Trendelenburg position during insertion; occlude catheter hub
Arrhythmia	Any (guidewire)	Advance wire no more than needed; monitor ECG
DVT	Femoral	Minimize dwell time

WikEM CVC | Merck Manual

Lumbar Puncture

Opening Pressure

• Normal: 10-20 cm H2O
• Measure with: Patient in lateral decubitus, legs extended
• Bacterial meningitis: Often greater than 25 cm H2O

CT Before LP Criteria

Safe to proceed without CT if all of the following are met (NEJM 2001 criteria):

• Age below 60
• Not immunocompromised
• No known CNS disease
• No seizure within 1 week
• Alert and following commands
• Normal neurologic exam

CT findings that prohibit LP: Midline shift, obstructive hydrocephalus, compressed basilar cisterns, posterior fossa mass

Platelet and INR Thresholds

Parameter	Threshold	Action
Platelets	below 25,000	Transfuse before LP
INR	greater than 1.5	Correct before LP
Hemophilia	Any	Replace factor pre-procedure

Tube Order

Tube	Study	Notes
Tube 1	Cell count and differential	Most likely to have traumatic blood
Tube 2	Gram stain, culture (bacterial + viral)	Sterile tube for microbiology
Tube 3	Glucose, protein	Least affected by traumatic tap
Tube 4	Second cell count or hold	For special tests: crypto Ag, AFB, VDRL, PCR

Bloody tap correction: Subtract 1 WBC per 750 RBC; subtract 1 mg/dL protein per 1000 RBC

CSF Interpretation

Pattern	WBC	Differential	Glucose	Protein
Bacterial	greater than 100	PMN 80-90%	Low (below 40)	High (greater than 100)
Viral	5-500	Lymphocytes	Normal	Normal to mildly elevated
Fungal / TB	10-500	Lymphocytes	Low	High
Subarachnoid hemorrhage	RBCs present	PMN early	Normal	Elevated

Pearls

• Atraumatic 22-ga needle reduces post-LP headache (2018 Lancet meta-analysis). Needle larger than 20 ga doubles headache risk
• CSF cultures may be negative 2 hr after parenteral antibiotics (meningococcal) or 6 hr (pneumococcal)
• Needle gauge: use 22 ga atraumatic when available; reserve 20 ga for obese patients or when opening pressure is critical

WikEM LP | Merck Manual

Thoracentesis

Pre-Procedure Labs

Parameter	Threshold	Notes
Platelets	below 50,000	Relative contraindication; evidence is thin — Hibbert et al (Chest 2013) found hemorrhagic complications infrequent even with abnormal coagulation under ultrasound
INR	greater than 2x normal	Relative contraindication per WikEM (McVay 1991)
Ultrasound guidance	Strongly recommended	Reduces pneumothorax risk

Maximum Safe Removal

• Traditional limit: ~1.5 L in 24 hr to prevent re-expansion pulmonary edema (RPE)
• Evidence note: Feller-Kopman (2007) found weak correlation between volume removed and RPE; experienced operators can drain more in monitored patients
• Stop if: Chest pain, dyspnea, hypotension

Complications

Complication	Rate	Notes
Pneumothorax	4-19%	Lower with ultrasound guidance
Cough	~9%	Usually self-limited
Re-expansion pulmonary edema	Rare	Risk may not correlate with volume
Hemothorax	Rare	Consider if chest tube needed
Splenic / liver puncture	Rare	Use ultrasound to mark site

WikEM Thoracentesis | Merck Manual

Paracentesis

Pre-Procedure Labs

• No pre-procedure labs routinely needed. Bleeding risk below 0.2% even in liver failure with elevated INR
• Contraindicated only in: Active bleeding or DIC

Maximum Safe Removal

• Therapeutic: 5-6 L well tolerated; up to 8 L in some patients
• Stop if: Hypotension, abdominal pain, vasovagal symptoms

Albumin Replacement

Volume Removed	Albumin Dose	Rationale
Less than 5 L	None needed	Low risk of post-paracentesis circulatory dysfunction
5 L or more	6-8 g per liter removed, or 50 g total	Prevents post-paracentesis circulatory dysfunction
SBP or renal insufficiency	1.5 g/kg	Reduces hepatorenal syndrome risk (Kwok 2013 meta-analysis)

SBP Diagnostic Criteria

Test	SBP Threshold	Notes
PMN count	at least 250 cells/mcL	Diagnostic of SBP
Culture	Positive	May be negative if prior antibiotics
SAAG	greater than 1.1 g/dL	Confirms portal hypertension as cause of ascites

Complications

Complication	Rate	Mitigation
Hemorrhage	0-0.93%	Ultrasound guidance; avoid epigastric vessels
Ascitic leak	~5%	Z-track technique; pressure dressing
Bowel perforation	~0.6%	Use blunt-tip needle; avoid midline scars
Infection	~0.6%	Sterile technique

WikEM Paracentesis | Merck Manual

Arterial Line

Setup

• 500 mL NS in pressure bag at 300 mm Hg
• Transducer at phlebostatic axis (4th intercostal space, mid-axillary line)
• Connect to monitor, open transducer to air, zero, then close
• Flush and check for air bubbles before use

Zeroing

• Transducer must be at level of the heart
• Every 5 cm below the heart = ~3.5 mm Hg over-read
• Every 5 cm above the heart = ~3.5 mm Hg under-read
• Re-zero after any position change

Waveform Interpretation

Waveform	Characteristics	Causes	Action
Normal	Sharp upstroke, dicrotic notch, gradual diastolic decline	—	—
Damped	Blunted upstroke, loss of dicrotic notch, narrowed pulse pressure	Air bubbles, clot, kinked catheter, vasospasm	Flush and aspirate; check for kinks
Overdamped	Slow rise, no dicrotic notch, falsely low systolic	Air in line, loose connections, catheter against vessel wall	Flush system; tighten connections; reposition catheter
Underdamped	Overshoot, exaggerated dicrotic notch, “ringing” after waveform	Long tubing, resonance artifact; overestimates SBP, underestimates DBP	Use shorter tubing; add damping device

Dicrotic notch position: Low notch = low SVR; high notch = high SVR

Pearls

• Preferred site: Radial (check Allen test for collateral flow)
• Ultrasound guidance increases first-pass success (Shiver 2006)
• Contraindications: No Doppler or palpable pulse, ipsilateral dialysis fistula, inadequate ulnar collaterals, burns or infection over site
• Coagulopathy: Radial preferred over femoral; prolonged pressure (10 min) may be needed after removal
• Hand ischemia: Rare — collateral flow usually protects; thrombosis typically recanalizes after catheter removal

WikEM Arterial line | Merck Manual