Daily Anesthesiology Research Analysis
Three studies stand out today for anesthesiology and critical care: a randomized trial shows intravenous lidocaine reduces oxygen-desaturation during propofol-based endoscopy sedation; a cadaveric study in BJA demonstrates conditions favoring intrafascicular spread after intraneural injections at brachial plexus roots; and a nationwide registry analysis finds accidental hypothermia in drowning OHCA associates with worse 180-day outcomes, likely reflecting confounding by submersion time.
Summary
Three studies stand out today for anesthesiology and critical care: a randomized trial shows intravenous lidocaine reduces oxygen-desaturation during propofol-based endoscopy sedation; a cadaveric study in BJA demonstrates conditions favoring intrafascicular spread after intraneural injections at brachial plexus roots; and a nationwide registry analysis finds accidental hypothermia in drowning OHCA associates with worse 180-day outcomes, likely reflecting confounding by submersion time.
Research Themes
- Sedation safety and adjunctive analgesia
- Regional anesthesia nerve injury mechanisms
- Resuscitation outcomes in drowning and accidental hypothermia
Selected Articles
1. Risk of intrafascicular spread after deliberate ex vivo intraneural injections of brachial plexus nerve roots.
In a cadaveric, ultrasound-guided series of deliberate intraneural injections at brachial plexus roots, intrafascicular spread occurred in 8/12 injections, particularly in mono- or bifascicular roots. Risk depended on fascicle diameter being >2× the 0.9 mm needle orifice length and full needle-orifice containment within a fascicle; roots with ≥3 fascicles showed no intrafascicular spread.
Impact: This study elucidates anatomical-mechanistic conditions for intrafascicular spread at the root level, directly informing regional anesthesia safety and needle-placement strategies.
Clinical Implications: Avoid needle-orifice containment within fascicles at root level; consider real-time ultrasound swelling monitoring, low injection pressures, and avoiding intraneural injections near neuroforaminal exits to mitigate intrafascicular injury risk.
Key Findings
- Intrafascicular spread detected in 8 of 12 intraneural injections, mainly in mono- or bifascicular roots; none in roots with ≥3 fascicles.
- Risk increased when fascicle diameter was >2× the 0.9 mm needle-orifice length and the entire orifice was within a fascicle.
- Ultrasound-confirmed nerve swelling validated intraneural placement; heparinized erythrocytes served as spread markers.
Methodological Strengths
- Ultrasound-guided standardized injections with objective swelling confirmation
- Use of heparinized erythrocytes as tracers to verify spread patterns
Limitations
- Ex vivo cadaveric model with limited sample size
- No in vivo clinical outcomes; generalizability to living tissue uncertain
Future Directions: Validate findings in vivo with injection-pressure monitoring and advanced imaging; map fascicular architecture variability to refine regional anesthesia safety guidelines at the root level.
BACKGROUND: We investigated the intraneural spread of injected fluid in brachial plexus nerve roots, examining the potential for intrafascicular spread and identifying influencing factors. METHODS: Twelve deliberate ultrasound-guided intraneural injections were performed at the ventral rami of the brachial plexus nerve roots at their exits from the neuroforamina in six fresh, unembalmed, cryopreserved human cadavers. A 22-G, 30-degree bevel echogenic regional anaesthesia needle was used. Each injection contained 1 ml of heparinised erythrocytes as a marker. Nerve swelling observed on ultrasound images confirmed intraneural injection. RESULTS: Intraneural spread was observed in 12 ventral rami of the six brachial plexi: C5 (1), C6 (3), C7 (5), C8 (2), and T1 (1). Among these, intrafascicular spread was detected in eight cases, six in monofascicular roots and two in bifascicular roots, though none in roots with three or more fascicles. The fascicle diameters in these cases (2.1-3.8 mm) were at least twice the diameter of the needle orifice, measured at 0.9 mm, which was entirely inside the fascicles. In the four cases with intraneural but without intrafascicular spread, the fascicle diameters were about two times the diameter of the needle orifice in three instances, but the entire needle orifice was not always inside a fascicle. CONCLUSIONS: In contrast with multifascicular peripheral nerves, intrafascicular spread was possible after deliberate intraneural injections near the neuroforaminal canal exit of the brachial plexus nerve roots in several monofascicular or bifascicular ventral rami if the fascicle diameter was more than twice the needle opening length and the entire opening was inside the fascicle.
2. Intravenous lidocaine decreased oxygen-desaturation episodes induced by propofol-based sedation for gastrointestinal endoscopy procedures: a prospective, randomized, controlled trial.
In a randomized controlled trial of 300 patients undergoing GI endoscopy with propofol-based sedation, IV lidocaine (1.5 mg/kg bolus + 4 mg/kg/h infusion) reduced oxygen-desaturation episodes (22% vs 39%, p=0.018) and involuntary movements (14% vs 26%, p=0.013), with fewer circulatory adverse events.
Impact: Provides randomized evidence that an inexpensive, widely available adjuvant can improve respiratory safety during procedural sedation.
Clinical Implications: Consider IV lidocaine as an adjunct in propofol-based GI endoscopy sedation to decrease hypoxic events and movement, using the studied regimen; monitor for lidocaine-related adverse effects.
Key Findings
- Oxygen-desaturation episodes decreased from 39% (control) to 22% with IV lidocaine (p=0.018).
- Involuntary body movements reduced (14% vs 26%, p=0.013) and fewer circulatory adverse events occurred with lidocaine.
- Severity of hypoxia and need for interventions were lower with lidocaine (p=0.017 and p=0.028, respectively).
Methodological Strengths
- Prospective randomized controlled design with trial registration
- Clinically meaningful primary outcome (oxygen-desaturation) and adequate sample size
Limitations
- Single-center study; blinding not specified in abstract
- Concomitant midazolam and sufentanil may confound propofol and lidocaine effects
Future Directions: Multicenter, blinded RCTs to confirm generalizability; dose-response and safety profiling across procedural populations; explore mechanisms reducing hypoxia.
BACKGROUND: As a popularly used analgesic adjuvant, intravenous (IV) lidocaine could reduce the consumption of propofol in painless gastrointestinal (GI) endoscopy. However, whether IV lidocaine could affect the incidence of oxygen-desaturation episodes (ODE) during painless GI endoscopy is still unknown. Therefore, we tested the hypothesis that IV lidocaine could decrease the incidence of propofol-induced ODE and involuntary movements in patients during GI endoscopy. METHODS: Three hundred twenty-two patients scheduled for GI endoscopy were randomly divided into lidocaine group and control group. After midazolam and sufentanil injection, a bolus of 1.5 mg/kg lidocaine was given and followed by continuous infusion of 4 mg/kg/h in lidocaine group, whereas the same volumes of saline solution in control group. Then, propofol was titrated to produce unconsciousness. The primary outcome was the incidence of ODE during the procedure. The secondary outcomes were the incidence of different degree of hypoxia and corresponding treatments and the involuntary body movements. RESULTS: A total of 300 patients were finally included in the analysis, 147 patients in lidocaine group and 153 in control group. The incidence of ODE was 22% in lidocaine group and 39% in control group (OR:0.052; 95%CI: 0.284-0.889; P = 0.018). IV lidocaine also improved the occurrence of different degree of hypoxia (P = 0.017) and needed few treatments (P = 0.028). The incidence of involuntary body movements (14% vs 26%, P = 0.013) and adverse circulatory events was decreased by IV lidocaine. CONCLUSIONS: IV lidocaine adjuvant to propofol-based sedation could reduce the incidence of oxygen-desaturation episodes and involuntary body movements, with fewer adverse circulatory events. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100053818. Registered on 30 November 2021.
3. The role of accidental hypothermia in drowning patients with out-of-hospital cardiac arrest: A nationwide registry-based cohort study.
In Danish registry data of 118 drowning OHCA patients, accidental hypothermia (<35°C) was associated with markedly higher 180-day mortality (69% vs 16%) and poor neurological outcome (74% vs 18%) versus normothermia, likely reflecting confounding by longer submersion and arrest severity.
Impact: Challenges assumptions that accidental hypothermia is neuroprotective in drowning OHCA, informing prognosis, triage, and research into confounding factors.
Clinical Implications: Do not assume hypothermia confers protection in drowning OHCA; prioritize rapid rescue and high-quality resuscitation, record core temperature, and interpret prognosis with awareness of submersion time confounding.
Key Findings
- Accidental hypothermia was associated with higher 180-day mortality (69% vs 16%) and poor neurological outcome (mRS >3: 74% vs 18%).
- Hypothermic patients more often had ongoing CPR at admission (45% vs 7%), ICU admission (70% vs 41%), and mechanical ventilation (78% vs 32%).
- Authors note likely confounding by prolonged submersion and arrest severity; causality cannot be inferred.
Methodological Strengths
- Nationwide registry with standardized Utstein drowning reporting
- Clinically meaningful 180-day outcomes including mRS and mortality
Limitations
- Observational design with potential residual confounding (e.g., submersion time)
- Relatively small cohort size and limited granular data on rewarming or targeted temperature management
Future Directions: Prospective data capturing submersion time, core temperature trajectories, and targeted temperature management to disentangle causality; explore protocols for hypothermic drowning resuscitation.
AIM: This study aimed to investigate the associations between hypothermia and mortality or poor neurological outcome in a nationwide cohort of drowning patients with out-of-hospital cardiac arrest (OHCA). METHODS: This nationwide, registry-based cohort study reported in-hospital data on drowning patients with OHCA following the Utstein Style For Drowning. Drowning patients with OHCA were identified in the Danish Cardiac Arrest Registry from 2016 to 2021. The primary outcome was the rate of mortality or poor neurological outcome (corresponding to a modified Rankin Scale [mRS] score > 3) at 180 days after the drowning incident in patients with OHCA and accidental hypothermia (<35 °C) vs normothermia (≥35 °C). RESULTS: This study identified 118 drowning patients with OHCA and found an increased rate of mRS > 3 at 180 days after the drowning incident in the hypothermic group compared to the normothermic group (74% vs 18%, p < 0.001). The 180-day mortality (mRS = 6) was 69% in the hypothermic group compared to 16% in the normothermic group (p < 0.001). The hypothermic group had higher rates of ongoing CPR at hospital admission (45% vs 7%, p < 0.001), intensive care unit admission (70% vs 41%, p = 0.003), and mechanical ventilation during hospitalisation (78% vs 32%, p < 0.001) compared to the normothermic group. CONCLUSION: Hypothermic drowning patients with OHCA had a higher risk of mortality or poor neurological outcome at 180 days compared to normothermic drowning patients with OHCA. This association may likely be explained by confounding factors such as prolonged submersion and cardiac arrest. Further research is warranted.