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[ Home ](https://mdster.com) 2. [ Blog ](https://mdster.com/blog) 3. [ Case Discussion ](https://mdster.com/blog?category=case-discussion) 4. Failed RSI in Obesity: Rapid Desaturation, Rescue Oxygenation, and Human Factors [ Case Discussion ](https://mdster.com/blog?category=case-discussion) Failed RSI in Obesity: Rapid Desaturation, Rescue Oxygenation, and Human Factors ================================================================================== A case discussion on unanticipated difficult intubation during urgent laparoscopy—why SpO₂ collapses fast, how to get oxygen back now, and how to coach the team afterward. [ MDster Editorial Team ](https://mdster.com/about) · Feb 07, 2026 · 9 min read · 103 [ Reviewed by Dr. Ali Ragab, MBBCH, MSc, MCAI ](https://mdster.com/medical-reviewers/dr-ali-ragab) [Editorial Policy](https://mdster.com/editorial-policy) | [Corrections Policy](https://mdster.com/corrections) [ Anesthesiology ](https://mdster.com/blog?tag=anesthesiology) [ Difficult Airway ](https://mdster.com/blog?tag=difficult-airway) [ Rapid Sequence Induction ](https://mdster.com/blog?tag=rapid-sequence-induction) [ Obesity & OSA ](https://mdster.com/blog?tag=obesity-osa) [ Airway Emergencies ](https://mdster.com/blog?tag=airway-emergencies) [ Human Factors ](https://mdster.com/blog?tag=human-factors) Share this article Share this post SpO₂ is 88% and falling, the laryngoscope is still in the mouth, and your CA-3 is narrating the epiglottis instead of the monitor. In obese, untreated OSA physiology, you don’t get the luxury of time—prolonged “one more look” becomes the critical error, not the Grade 3b view. Case vignette (compressed to the decision points) ------------------------------------------------- A 35-year-old man (105 kg, BMI 35) needs an urgent laparoscopic appendectomy. Mild asthma, untreated OSA, Mallampati III, thick neck, limited extension. RSI with propofol and succinylcholine. First attempt: Grade 3b, tube won’t pass. Second attempt happens immediately—no change in blade, position, or plan. At ~3 minutes of apnea, SpO₂ is 85% and the resident is visibly fixated. In real time, you should be thinking in parallel: (1) oxygenation, (2) limiting trauma/edema that will make rescue harder, (3) getting a team back on a shared mental model. Immediate management: oxygenation is the procedure -------------------------------------------------- The DAS unanticipated difficult intubation guideline is explicit about prioritizing oxygenation, limiting attempts, and forcing a “stop and think” moment before the situation becomes CICO.[\[1\]](#cite-1 "Reference [1]") The fastest way to change the trajectory is to **declare failure out loud** and **change the task from intubation to oxygenation**. I would take the laryngoscope away (gently, without a final “peek”), and run a stepwise approach that is *algorithmic but not rigid*: ### Re-establish team function while you re-establish ventilation - **Declare**: “Failed intubation, desaturating—oxygenation plan now.” (This is a cognitive off-ramp for task fixation.) - **Call for help early**: second anesthesiologist + airway cart; ask someone to open the cric kit. - **Assign roles**: one person on drugs/hemodynamics, one on equipment, one on time/SpO₂ callouts. ASA’s 2022 guidance repeatedly emphasizes situational awareness (attempts, time, saturation) and limiting repeated attempts—this is where an attending’s running commentary matters.[\[2\]](#cite-2 "Reference [2]") ### Plan B now (not later): rescue oxygenation with a second-generation SGA If SpO₂ is already 85% in an obese apneic patient, I’m not “optimizing for the perfect view”; I’m **optimizing for the first effective breath**. - Insert a **second-generation SGA** (e.g., i-gel/LMA Supreme-class device) as the default rescue pathway after failed intubation. DAS specifically recommends second-generation SADs in failed intubation/RSI scenarios.[\[1\]](#cite-1 "Reference [1]") - If cricoid pressure is being applied and it’s impeding ventilation/SGA insertion, **release it under control**; DAS acknowledges this trade-off and advises removal when difficulty is encountered.[\[1\]](#cite-1 "Reference [1]") - Ventilate with 100% O₂, add **PEEP**, and confirm efficacy with chest rise and **ETCO₂**. If ventilation via SGA is effective and SpO₂ returns, you’ve bought time. That time should not be spent “trying again because the sat looks good now”; it should be spent choosing the least-bad definitive plan. ### If SGA isn’t immediately working: two-person mask ventilation done like you mean it Before declaring CICO, earnestly attempt best-practice mask ventilation: - **Ramped/head-up** repositioning (obesity + limited extension makes this therapeutic, not cosmetic). - OPA (and NPA if appropriate), two-handed seal with jaw thrust, high flows, PEEP. - Ensure full paralysis (incomplete relaxation is a common, fixable contributor to “can’t ventilate” in the early phase). DAS explicitly incorporates paralysis into the pathway when mask ventilation is failing.[\[1\]](#cite-1 "Reference [1]") ### CICO threshold and Plan D: prepare early, act decisively If you cannot oxygenate by mask or SGA, declare **CICO** and move to **front-of-neck access**—not after “one more” SGA attempt that’s indistinguishable from panic. DAS Plan D standardizes a scalpel technique with a cuffed tube to restore conventional ventilation.[\[1\]](#cite-1 "Reference [1]") In practice, the key is that **FONA preparation starts while you are still attempting oxygenation**—landmarks palpated, kit opened, someone gowned/gloved—so that the *decision* to cut is not delayed by the *logistics* of cutting. > **Clinical pearl:** In a desaturating obese patient, your most important airway skill is not “getting the tube”; it’s recognizing when intubation has become the wrong problem and switching the team to oxygenation before hypoxia makes every plan worse. ### A simple trigger table that keeps you honest TriggerWhat I do next (and say out loud)Failed first attempt with poor view“Stop—change something.” Reposition/ramp, different device (VL), external laryngeal manipulation, bougie-ready.SpO₂ trending down / time passing“Oxygenation takes priority.” Mask/SGA now, not after another look.Can’t oxygenate with mask/SGA“This is CICO.” Move to DAS Plan D (FONA) while continuing best-effort oxygenation.[\[1\]](#cite-1 "Reference [1]") Why desaturation was so fast in this patient -------------------------------------------- When boards ask “why does the obese patient desaturate faster,” they usually want the **reduced oxygen reserve from decreased FRC** (often compounded by atelectasis after induction). In day-to-day practice, I also remind trainees that increased O₂ consumption and V/Q mismatch add slope to the curve—but the dominant lever is **less reservoir**. That physiology should change your pre-induction behavior: head-up preoxygenation, PEEP/CPAP during preoxygenation in high-risk patients, and apneic oxygenation when feasible—consistent with DAS emphasis on positioning and apneic oxygenation in high-risk patients.[\[1\]](#cite-1 "Reference [1]") After rescue oxygenation: proceed, intubate-through-SGA, or wake? ----------------------------------------------------------------- Once the SGA is ventilating well and SpO₂ is stable (98%), you must avoid a new bias: “We’re fine now, so we can just keep going.” DAS explicitly frames this as the moment to stop and think: wake the patient, proceed with SGA, or intubate through the device using guided techniques.[\[1\]](#cite-1 "Reference [1]") For urgent lap appendectomy, pneumoperitoneum and aspiration risk usually make an ETT preferable. If the case can tolerate delay, **waking the patient** is often the safest default (DAS Plan C).[\[1\]](#cite-1 "Reference [1]") If surgery truly cannot wait, an **SGA as a conduit** with flexible bronchoscopic guidance (and a team experienced in the technique) is a reasonable escalation; the point is that this should be an *intentional plan*, not an impulsive return to direct laryngoscopy. Airway injury: what you look for (and what actually happens most) ----------------------------------------------------------------- After multiple laryngoscopy attempts, I look for dental injury, mucosal bleeding, lip/tongue trauma, and voice changes. The **most frequent patient-reported complication** after routine direct laryngoscopy/intubation is still sore throat/hoarseness; meanwhile, dental trauma remains disproportionately important medicolegally. If you wake the patient, document what happened, why you stopped, and what follow-up you advised. ASA’s 2022 guideline stresses documentation and providing the patient with information about the difficult airway encounter.[\[2\]](#cite-2 "Reference [2]") Human factors: naming the bias is not the same as fixing it ----------------------------------------------------------- The resident’s “paralysis” is usually a blend of **plan-continuation bias** and **attentional tunneling** under stress. The cure is partly culture (it must be acceptable to say “failed” early), and partly system design: cognitive aids, role assignment, and explicit time/SpO₂ callouts. NAP4’s legacy is that catastrophic airway harm is often a human-factors story with a technical epilogue; it also drove system-level recommendations (e.g., airway leads, equipment readiness, and universal capnography in relevant locations).[\[3\]](#cite-3 "Reference [3]") ### Debriefing: structure and primary goal In debrief, the goal is not to “tell them what you would have done,” but to rebuild the resident’s internal model while maintaining psychological safety. - **Reaction/defuse**: “Talk me through what that felt like when the sat started falling.” - **Analysis**: focus on decision points—attempt limits, what cues were missed, what would trigger a change to oxygenation. - **Summary/application**: commit to 2–3 specific behaviors next time (e.g., “change something every attempt,” “verbalize SpO₂/time,” “SGA by X% saturation”). Clinical application (what I would change next time before induction) --------------------------------------------------------------------- - Treat this as a **physiologically difficult airway**: optimize preoxygenation (head-up, PEEP/CPAP as tolerated), consider apneic oxygenation.[\[1\]](#cite-1 "Reference [1]") - Make the first attempt count: ramping, VL-first strategy if available and you’re proficient; have a bougie and a second device open. - Brief the team on failure points: “If first attempt fails, we reposition/change device. If SpO₂ falls, we oxygenate with SGA. If can’t oxygenate, we cut.” (DAS language helps.)[\[1\]](#cite-1 "Reference [1]") - Supervision clarity matters: **direct supervision** is you in the room, watching the attempt and ready to intervene; **indirect supervision** is you immediately available but not physically present (a different risk profile when seconds matter). Key Points for Board Exams -------------------------- - In failed RSI with desaturation, **oxygenation supersedes intubation**; declare failure early and move to rescue oxygenation.[\[1\]](#cite-1 "Reference [1]") - Obesity accelerates desaturation primarily via **reduced FRC/oxygen reserve**. - DAS 2015: limit attempts (3+1 concept), use a **second-generation SGA** for rescue, and progress to **Plan D (FONA)** if CICO.[\[1\]](#cite-1 "Reference [1]") - ASA 2022: emphasize **situational awareness (time/attempts/SpO₂)**, consider awake pathways when apnea intolerance is high, and **document** the event for the patient/record.[\[2\]](#cite-2 "Reference [2]") - NAP4: catastrophic outcomes frequently involve **human factors**; system fixes (training, leadership, capnography culture) matter.[\[3\]](#cite-3 "Reference [3]") Conclusion ---------- The “airway emergency” in this case wasn’t the Grade 3b view—it was the unchecked drift into task fixation while an obese patient burned through a small oxygen reservoir. If you can train residents to verbalize failure early, switch the goal to oxygenation, and execute a rehearsed DAS-style escalation with clear roles, you prevent the spiral where every subsequent attempt becomes harder, bloodier, and later than it should have been. References (3) ------------------ 1. 1. [ academic.oup.com/bja/article/115/6/827/241440 ](https://academic.oup.com/bja/article/115/6/827/241440) [↩](#cite-ref-1-1 "Back to text") 2. 2. [ www.apsf.org/article/anesthesia-patient-safety-foundation-update-2022-american-society-of-anesthesiologists-practice-guidelines-for-management-of-the-difficult-airway ](https://www.apsf.org/article/anesthesia-patient-safety-foundation-update-2022-american-society-of-anesthesiologists-practice-guidelines-for-management-of-the-difficult-airway/) [↩](#cite-ref-2-1 "Back to text") 3. 3. [ www.rcoa.ac.uk/research/research-projects/national-audit-projects-naps/nap4-major-complications-airway-management ](https://www.rcoa.ac.uk/research/research-projects/national-audit-projects-naps/nap4-major-complications-airway-management) [↩](#cite-ref-3-1 "Back to text") Next step Build momentum in Anesthesiology with focused, exam‑style practice -------------------------------------------------------------------- - Airway, ventilation, and crisis drills - High‑yield anesthesia pharmacology made practical - Track weak topics and improve faster [ Start practicing ](https://mdster.com/user/dashboard) [ Explore Anesthesiology ](https://mdster.com/speciality/anesthesiology) [ View pricing ](https://mdster.com/pricing) [ Explore features ](https://mdster.com/features) No credit card required. Full access to all features. No commitment. Cancel anytime. 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