Publication

• Title: A Multicenter, Randomized Trial of Ramped Position vs Sniffing Position During Endotracheal Intubation of Critically Ill Adults
• Acronym: Check-UP (Checklists and Upright Positioning in endotracheal intubation of critically ill patients)
• Year: 2017
• Journal published in: CHEST
• Citation: Semler MW, Janz DR, Russell DW, Casey JD, Lentz RJ, Zouk AN, et al. A Multicenter, Randomized Trial of Ramped Position vs Sniffing Position During Endotracheal Intubation of Critically Ill Adults. Chest. 2017;152(4):712-722.

Context & Rationale

• Background

  • Peri-intubation hypoxaemia is the most frequent complication of tracheal intubation in critically ill adults, with plausible links to peri-arrest haemodynamic collapse and death.
  • “Ramped” positioning (head-up elevation with modified head/neck alignment) improves preoxygenation and/or laryngoscopic view in elective operating theatre studies, especially in obesity, but had not been tested in ICU intubations.
  • ICU intubation differs materially from elective anaesthesia (physiological instability, urgency, variable preoxygenation, trainee operators), so translation from theatre practice was uncertain.
• Research Question/Hypothesis

  • Among critically ill adults undergoing endotracheal intubation in ICU, does ramped positioning (25° head-of-bed elevation) improve oxygenation compared with sniffing position?
  • Hypothesis: ramped positioning would increase the lowest oxygen saturation measured during and immediately after intubation.
• Why This Matters

  • If beneficial, positioning would be a low-cost, instantly scalable safety intervention.
  • If harmful (eg, poorer laryngoscopy/first-pass success), routine adoption could increase airway-related adverse events in high-risk ICU physiology.
  • The trial addressed a common “theatre-to-ICU” extrapolation with high face validity but limited critical care–specific evidence.

Design & Methods

• Research Question: In critically ill adults intubated in ICU by pulmonary/critical care medicine fellows, does a ramped position (25° head-of-bed elevation) vs a sniffing position improve lowest oxygen saturation during intubation?
• Study Type: Multicentre, pragmatic, randomised trial conducted in four ICUs; the overall Check-UP platform used a 2×2 factorial design (positioning and a pre-intubation checklist), with this index report focused on the positioning comparison.
• Population:
  • Setting: ICU intubations performed by pulmonary and critical care medicine fellows (July 2015 to July 2016).
  • Inclusion: adults (≥18 years) requiring endotracheal intubation where the intubating clinician planned induction with sedative medication and neuromuscular blockade.
  • Key pre-randomisation exclusions (operational): intubations deemed too urgent to permit enrolment procedures; clinician requirement for a specific position; awake intubation; age <18 years.
• Intervention:
  • Ramped position: bed adjusted to elevate the head-of-bed to 25° while maintaining the lower half of the bed parallel to the floor.
  • Head positioning instruction: occiput positioned at the upper edge of the bed so that the patient’s face was parallel to the ceiling.
• Comparison:
  • Sniffing position: bed kept horizontal (no torso elevation permitted).
  • Neck flexion/head extension achieved using folded blankets under the head and neck.
• Blinding: Unblinded (operators and bedside staff aware of assigned position); primary outcome based on pulse oximetry was objective but procedural outcomes included operator-reported measures.
• Statistics: A total of 260 patients were required to detect a 5% absolute increase in lowest oxygen saturation (assumed SD 14%) with 80% power at the 5% significance level; primary analysis was intention-to-treat (unadjusted), with prespecified sensitivity and subgroup analyses.
• Follow-Up Period: Primary outcome measured from induction through 2 minutes post-intubation; clinical outcomes followed through ICU stay and hospital discharge.

Key Results

This trial was not stopped early. Enrolment completed as planned (n=260; 130 per group).

• Ramped positioning did not improve oxygenation: median lowest SpO₂ 93% (IQR 84–99) vs 92% (79–98); P=0.27.
• Ramped positioning was associated with worse laryngoscopy-related outcomes (grade III/IV view 25.4% vs 11.5%; first-pass success 76.2% vs 85.4%) and greater use of rescue adjuncts (bougie 19.2% vs 6.2%).
• No statistically significant differences were observed in haemodynamic endpoints or downstream clinical outcomes (including hospital mortality), acknowledging limited power for these endpoints.

Internal Validity

• Randomisation and allocation: Computer-generated permuted blocks with stratification by ICU; concealed allocation via sequentially numbered opaque envelopes opened after the decision to intubate.
• Post-randomisation exclusions / missingness: No post-randomisation exclusions reported; primary outcome missing for 3/130 in each arm (analysed n=127 per group).
• Blinding and bias risk: Unblinded intervention; primary outcome (SpO₂) objective, but procedural outcomes (eg, Cormack–Lehane grade, “difficulty”) were operator-reported and susceptible to expectation/measurement bias.
• Protocol adherence: Crossovers were rare (1 assigned sniffing received ramped; 2 assigned ramped received sniffing).
• Separation of the variable of interest: In a measured convenience sample (n=35), head-of-bed angle was 25° (IQR 23–25) in the ramped group vs 0° (IQR 0–0) in the sniffing group (P<0.001).
• Baseline balance and illness severity: Groups were well matched (eg, age median 56 years in both; APACHE II median 22 vs 21; baseline SpO₂ at induction 99% [93–100] vs 99% [95–100]).
• Heterogeneity and operator effects: Thirty fellows performed intubations (median 6 intubations each); self-reported experience suggested substantially greater familiarity with sniffing than ramped positioning (median prior intubations 37 vs 10 among those reporting), a plausible influence on first-pass outcomes.
• Timing and selection: A large proportion of potentially eligible intubations were not randomised because they were too urgent for enrolment procedures (selection away from the most time-critical airways).
• Statistical rigour: Sample size target met; intention-to-treat analysis with prespecified sensitivity analyses; the study was powered for a difference in lowest SpO₂, not for mortality or ICU outcomes.

Conclusion on Internal Validity: Overall, internal validity appears moderate-to-strong given concealed randomisation, minimal crossover, and an objective primary outcome; key limitations are lack of blinding, operator-reported procedural endpoints, and potential performance effects related to differential operator familiarity with the assigned positions.

External Validity

• Population representativeness: Typical ICU adult cohort (high illness severity; common indications included hypoxaemic respiratory failure), but restricted to intubations performed by pulmonary/critical care fellows with planned sedative + neuromuscular blockade.
• Exclusions affecting generalisability: Most urgent intubations were frequently excluded (too urgent to enrol), and cases where clinicians required a specific position were excluded.
• Setting and technique dependence: “Ramped” positioning was delivered via ICU bed head-of-bed elevation to 25° with specified head placement; results may not translate to other ramping techniques (eg, blanket “ramp” to align external auditory meatus with sternal notch).
• Applicability across systems/operators: Findings are most applicable to academic ICUs with trainee intubators; transferability to anaesthesia-led teams, emergency departments, prehospital care, and resource-limited settings is uncertain.

Conclusion on External Validity: Generalisability is moderate for routine ICU intubations in similar academic contexts, but is limited for highly emergent airways, non-ICU settings, and different “ramped” implementations or operator skill-mix.

Strengths & Limitations

• Strengths:
  • Randomised, multicentre ICU trial addressing a common practice extrapolated from theatre to critical care.
  • Objective, clinically relevant primary endpoint with prespecified power calculation and intention-to-treat analysis.
  • Clear, protocolised definitions for the two positioning strategies and low crossover.
  • Independent observers collected physiologic data during the procedure.
• Limitations:
  • Unblinded intervention; important procedural outcomes were operator-reported.
  • Restricted to fellow-performed intubations; differential familiarity with sniffing vs ramped may have influenced procedural success.
  • Many urgent intubations were not enrolled, potentially limiting applicability to the highest-risk scenarios.
  • Single “dose” of ramping (25° head-of-bed elevation) may not reproduce theatre-style ramping geometry in obesity; the degree of head/neck alignment achieved was not routinely measured.
  • Trial not powered for downstream clinical outcomes (eg, mortality), so neutral findings there are imprecise.

Interpretation & Why It Matters

• Implication for bedside positioning

  For routine ICU intubations using the study’s technique (25° head-of-bed elevation), ramped positioning did not improve peri-intubation oxygenation and was associated with worse laryngoscopic conditions and first-pass success; sniffing position appears a reasonable default when no other indication mandates head-up positioning.
• What the results do (and do not) mean

  The findings argue against assuming theatre-derived benefits of ramping automatically translate to the ICU; they do not exclude benefit from alternative ramping techniques (eg, true “ramp” alignment in severe obesity) or in subgroups under-represented by enrolment constraints.
• How it aligns with modern ICU airway practice

  Subsequent ICU intubation guidance has prioritised comprehensive preparation and mitigation of physiological collapse (preoxygenation strategy, attempt limitation, vasopressor readiness) over any single positioning manoeuvre as a universal solution.⁵

Controversies & Subsequent Evidence

• Why oxygenation benefit was not observed (mechanistic debate):
  • The accompanying editorial highlighted that preoxygenation and peri-procedural management were not standardised, and that ICU “ramping” via bed elevation may differ from theatre ramping geometry, potentially blunting physiological benefit while introducing procedural difficulty.¹
• Position definitions and the obesity question:
  • In correspondence, the investigators emphasised that the trial included a substantial obese subgroup (BMI ≥30 kg/m² in 37.1%) and that prespecified analyses did not show benefit of ramped positioning by BMI category; they also noted ongoing uncertainty about the optimal technique at BMI extremes and the practical challenge of achieving ideal head/neck alignment in the ICU environment.²
• Factorial checklist component and broader intubation safety interventions:
  • The Check-UP platform’s checklist component was subsequently published separately; the written pre-intubation checklist did not improve oxygenation or key safety outcomes in critically ill adults.³
• Meta-analytic signal since Check-UP:
  • A systematic review and meta-analysis evaluating ramped vs sniffing positioning across studies reported no consistent advantage of ramped positioning for key intubation outcomes, broadly aligning with the direction of effect observed in the ICU trial.⁴

Summary

• In 260 ICU intubations by pulmonary/critical care fellows, ramped positioning (25° head-of-bed elevation) did not increase the lowest peri-intubation oxygen saturation compared with sniffing position.
• Ramped positioning was associated with poorer laryngoscopic conditions (higher grade III/IV view) and lower first-pass success, with greater use of rescue adjuncts.
• Haemodynamic endpoints and clinical outcomes (including hospital mortality) were not significantly different, but the trial was not powered for these outcomes.
• Findings challenge routine adoption of bed-elevated ramping as an oxygenation strategy in ICU intubation and highlight the need to consider operator familiarity and the precise “dose/geometry” of ramping.
• Subsequent evidence and guidance emphasise comprehensive ICU airway preparation over any single positioning manoeuvre as a universal safety intervention.

Overall Takeaway

CHECKUP provided ICU-specific randomised evidence that a pragmatic “ramped” technique (25° head-of-bed elevation on an ICU bed) does not improve peri-intubation oxygenation compared with sniffing position, and may worsen first-pass success and laryngoscopic view when performed by trainee operators. The trial shifted practice away from assuming theatre-derived positioning benefits apply universally in critical care, and reinforced that ICU airway safety hinges on comprehensive preparation and physiology management rather than any single manoeuvre.

Bibliography

• 1. Scott J, Walz JM, Heard SO. Should the ramped position be “sniffed at” in the ICU? Chest. 2017;152(4):693-694.
• 2. Semler MW, Janz DR, Lentz RJ, et al. Response. Chest. 2017;152(6):1351.
• 3. Janz DR, Semler MW, Joffe AM, Casey JD, Lentz RJ, et al. Effect of a checklist on endotracheal intubation of critically ill adults: a randomized controlled trial. Chest. 2018;153(4):816-824.
• 4. Okada Y, Nakayama Y, Hashimoto K, Koike K, Watanabe N. Ramped versus sniffing position for tracheal intubation: a systematic review and meta-analysis. Am J Emerg Med. 2021;44:250-256.
• 5. Higgs A, McGrath BA, Goddard C, Rangasami J, Suntharalingam G, Gale R, Cook TM. Guidelines for the management of tracheal intubation in critically ill adults. Br J Anaesth. 2018;120(2):323-352.