Emergency Medicine · Medical Literature
Patient Monitor Position and Operator Ability to Visualize a Desaturation Event During Intubation.
Abstract
During endotracheal intubation, equipment setup typically includes the patient monitor fixed at the head of the bed behind the back of the operator. Inability to directly visualize the patient monitor may result in delayed recognition of desaturation. Our primary aim in this study was to measure the association between patient monitor position and the time to recognition of a desaturation event during endotracheal intubation. We performed a randomized crossover trial of emergency medicine residents across two Accreditation Council for Graduate Medical Education-accredited programs. Subjects were asked to perform direct and video-assisted laryngoscopy once on a difficult airway trainer in a simulation. The sequence of laryngoscopy modality (direct vs video-assisted) and monitor position (head vs left vs right of bed) were randomized prior to each attempt. The simulated patient's peripheral capillary oxygen saturation (SpO2) was programmed to begin at 100% and decrease at a rate of 1% per second 10 seconds after the start of the subject's attempt. The primary outcome measure was time to operator recognition of hypoxia defined as the observed period during which the simulated SpO2 was < 90%. Secondary outcomes were operator failure to visualize a desaturation event. We rendered Kaplan-Meier curves illustrating the time to visualization of hypoxia and performed a Cox regression adjusting for laryngoscopy modality and total number of previous intubations performed. Using multivariable linear regression, we modeled the association between time to recognition of hypoxia in seconds and patient monitor position with similar adjustments. To assess differences in the number of observed failure events between study arms, we used chi-squared or Fisher exact tests. The threshold for statistical significance was a two-sided P < 0.05. We observed 68 attempts by 34 subjects. Twenty-two (32.5%), 22 (32.5%), and 24 (35%) intubations were performed with the monitor positioned at the head, left, and right, respectively. The median times to recognition of hypoxia were 37 seconds [sec] (95% CI, 25-86 sec) for the head, 32 sec (95% CI, 18-50 sec) for the left, and 23 sec (95% CI, 19-34 sec) for the right groups, respectively. Cox regression demonstrated hazard ratios of 2.7 and 3.2 for the left and right groups when compared to the head group, and these findings were statistically significant (P = .04 and P = 0.03, respectively). We found no statistically significant associations between time to recognition of hypoxia and laryngoscopy modality or total number of previous intubations (P = .82 and .21, respectively). Failure rates across head, left, and right groups were similar, at 36%, 59%, and 50%, respectively (P = .30). Positioning of the patient monitor at the head of the bed results in delayed visualization of desaturation events during simulated direct and video-assisted laryngoscopy across different levels of experience. Ideally, the patient monitor should be positioned on the side of the bed and within the operator's direct line of sight. Further research is warranted to assess how equipment setup may impact procedural performance, operator ergonomics, and patient safety.
Clinical relevance
Does patient monitor position (at the head vs. the left vs. the right side of the bed) affect the time for an intubating operator to recognize a simulated desaturation event during direct or video-assisted laryngoscopy? __SNAPSHOT__ {"studyDesign":"Randomized crossover trial (simulation-based)","setting":"Two ACGME-accredited emergency medicine residency programs; simulation laboratory using a difficult airway trainer","sampleSize":"Not reported in abstract (number of resident subjects not specified)","population":"Emergency medicine residents at two ACGME-accredited programs; all subjects performed both direct laryngoscopy and video-assisted laryngoscopy","intervention":"Patient monitor positioned at the left or right side of the bed (within operator's direct line of sight) during simulated endotracheal intubation","comparator":"Patient monitor positioned at the head of the bed (conventional placement, behind the operator's back) during simulated endotracheal intubation","primaryOutcome":"Time (in seconds) to operator recognition of hypoxia, defined as the observed period during which simulated SpO2 was <90%","followUp":"Single simulation session (no longitudinal follow-up); not reported beyond the procedural attempt","fundingSource":"Not reported"}
Key findings
Monitor position at the head of the bed was associated with substantially longer time to recognition of hypoxia compared with lateral monitor placement. Median times to recognition of hypoxia were 37 seconds (95% CI, 25–86 s) for the head-of-bed group, 32 seconds (95% CI, 18–50 s) for the left-of-bed group, and 23 seconds (95% CI, 19–34 s) for the right-of-bed group. Cox proportional hazards regression demonstrated hazard ratios of 2.7 (left vs. head, p=0.04) and 3.2 (right vs. head, p=0.03), indicating that operators were approximately 2.7–3.2 times more likely to detect hypoxia at any given moment when the monitor was placed laterally compared with at the head of the bed—both statistically significant. Neither laryngoscopy modality (direct vs. video-assisted, p=0.82) nor total number of prior intubations performed by the operator (p=0.21) was significantly associated with time to recognition of hypoxia. For the secondary outcome, failure rates (complete non-recognition of the desaturation event) were numerically higher in the lateral groups (left: 59%, right: 50%) compared with the head group (36%), though this difference did not reach statistical significance (p=0.30). NNT/NNH for failure to recognize desaturation were not calculable from reported data. Adverse events were not applicable in this simulation context.
Practice implications
This simulation-based crossover trial demonstrates that conventional head-of-bed monitor placement is associated with statistically significant delays in operator recognition of intraoperative desaturation during both direct and video-assisted laryngoscopy, with a 14-second median delay compared with right lateral placement. The effect was consistent across levels of operator experience and laryngoscopy modality, suggesting this is primarily an ergonomic/line-of-sight phenomenon rather than a skill-dependent one. Importantly, the study did NOT establish that lateral monitor placement reduces actual patient harm, hypoxic events, or adverse clinical outcomes—only that recognition latency is shorter in a controlled simulation. The surprisingly high failure rates in the lateral monitor groups (50–59%) compared with head position (36%), though not statistically significant, raise a hypothesis-generating concern that lateral placement may paradoxically introduce different attentional challenges; this warrants further study. Findings apply specifically to EM residents in a simulation lab and may not generalize to attending physicians, nurses, respiratory therapists, or real clinical environments where team dynamics, auditory alarms, and situational complexity differ markedly. Only abstract-level data are available; full methodological details (sample size, randomization adequacy, blinding strategy, and whether monitors displayed auditory alarms) could not be verified and represent important uncertainties. __LIMITATIONS__ Simulation-based study: findings may not translate to real clinical environments where auditory alarms, team communication, and environmental distractors differ substantially from a controlled lab.,Sample size not reported in the abstract; statistical power for the secondary failure-rate outcome (p=0.30) was likely insufficient, representing a type II error risk.,Crossover design with within-subject randomization is appropriate but susceptible to learning/fatigue effects across repeated attempts; adequacy of washout or counterbalancing not verifiable from the abstract.,Population limited to EM residents; generalizability to attending physicians, non-physician practitioners, or providers in other specialties is unknown.,The paradoxically higher (though non-significant) failure-to-recognize rates in lateral monitor groups (59% and 50% vs. 36% head) are unexplained and potentially important; this pattern is not discussed in the abstract.,No assessment of whether auditory SpO2 alarms were active or disabled, which would profoundly affect recognition latency regardless of visual monitor position.,Primary outcome (time to visual recognition of hypoxia) is a process measure; no patient-centered outcomes (e.g., rates of clinical desaturation, first-pass success, harm) were assessed.,Funding source not reported; potential conflicts of interest cannot be assessed.,Simulation fidelity limitations: a difficult airway trainer may not replicate the cognitive load, physiologic variability, or team dynamics of live patient intubation. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ In this simulation-based randomized crossover trial, positioning the patient monitor at the head of the bed—the conventional setup during intubation—was associated with significantly longer times to operator recognition of hypoxia (median 37 s vs. 23 s for right lateral placement; HR ~3.2 favoring lateral positioning, p=0.03). These findings support repositioning the patient monitor to the lateral side of the bed and within the operator's direct line of sight during intubation, a low-cost, zero-risk ergonomic change. However, confirmation in real clinical environments with actual patients, full team dynamics, and auditory alarm conditions is needed before this represents a practice standard.