The effects of jaw thrust and the lateral position on heart rate variability in anesthetized children with obstructive sleep apnea syndrome

Left Head Rotation as an Alternative to Difficult Tracheal Intubation: Randomized Open Label Clinical Trial

BACKGROUND

Tracheal intubation is a life-saving intervention, and optimizing the patient's head and neck position for the best glottic view is a crucial step that accelerates the procedure. The left head rotation maneuver has been recently described as an innovative alternative to the traditional sniffing position used for tracheal intubation with marked improvement in glottic visualization.

OBJECTIVE

This study compared the glottic view and intubating conditions in the sniffing position versus left head rotation during direct laryngoscopy.

METHODS

This randomized, open-label clinical trial enrolled 52 adult patients admitted to Baguio General Hospital and Medical Center from September 2020 to January 2021 for an elective surgical procedure requiring tracheal intubation under general anesthesia. Intubation was done using a 45° left head rotation in the experimental group (n=26), while the control group (n=26) was intubated using the conventional sniffing position. Glottic visualization and intubation difficulty with the two procedures were assessed using the Cormack-Lehane grade and Intubation Difficulty Scale, respectively. Successful intubation is measured by observing a capnographic waveform in the end-tidal CO2 monitor after placement of the endotracheal tube.

RESULTS

There was no statistically significant difference in the Cormack-Lehane grade, with 85% (n=44) of patients classified under grades 1 (n=11 and n=15) and 2 (n=11 and n=7) in the left head rotation and sniffing position groups, respectively. In addition, there were no statistically significant differences in the Intubation Difficulty Scale scores of patients intubated with left head rotation or sniffing position; 30.7% (n=8) of patients in both groups were easily intubated, while 53.8% (n=14) in left head rotation and 57.6% (n=15) in sniffing position groups were intubated with slight difficulty. Similarly, there were no significant differences between the 2 techniques in any of the 7 parameters of the Intubation Difficulty Scale, although numerically fewer patients required the application of additional lifting force (n=7, 26.9% vs n=11, 42.3%) or laryngeal pressure (n=3, 11.5% vs n=7, 26.9%) when intubated with left head rotation. The intubation success rate with left head rotation was 92.3% versus 100% in the sniffing position, but this difference was not statistically significant.

CONCLUSIONS

Left head rotation produces comparable laryngeal exposure and intubation ease to the conventional sniffing position. Therefore, left head rotation may be an alternative for patients who cannot be intubated in the sniffing position, especially in hospitals where advanced techniques such as video laryngoscopes and flexible bronchoscopes are unavailable, as is the case in this study. However, since our sample size was small, studies with a larger study population are warranted to establish the generalizability of our findings. In addition, we observed inadequate familiarity among anesthesiologists with the left head rotation technique, and the intubation success rate may improve as practitioners attain greater technical familiarization.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number (ISRCTN)ISRCTN23442026; https://www.isrctn.com/ISRCTN23442026.

Analysis of nasal resistance regulation mechanism during postural changes in patients with obstructive sleep apnea by measuring heart rate variability

STUDY OBJECTIVES

Changes in nasal resistance (NR) during postural changes are influenced by venous filling pressure and autonomic nervous system mediation, and heart rate variability (HRV) can reflect changes in the autonomic nervous system. This study aimed to explore the regulatory mechanisms of NR in patients with obstructive sleep apnea (OSA) during postural changes.

METHODS

Healthy controls (apnea-hypopnea index < 5 events/h) and patients with OSA were recruited. NR and electrocardiogram data were collected in sitting, supine, left-lateral, and right-lateral postures. HRV parameters were obtained by analyzing the electrocardiogram data from each posture. Subgroups were divided according to sitting-supine NR changes, and HRV parameters were compared between different postures and groups/subgroups.

RESULTS

In total, 34 healthy controls and 39 patients with OSA (mean apnea-hypopnea index 34.34 ± 22.44 events/h) were recruited. During sitting-supine postural changes, the NR increased in the control group but did not change significantly in the OSA group. None of the autonomic nervous system-related HRV parameters changed significantly. After the groups were divided into NR-elevated and NR-unchanged subgroups, sympathetic activity-related HRV parameters were higher in the NR-unchanged subgroup but only statistically significant in the OSA group. When comparing the left and right postures, there was no significant change in NR; however, the OSA group had lower parasympathetic activity-related HRV parameters when in the right posture.

CONCLUSIONS

During postural changes from the sitting to supine positions, the total NR increases, and this increment is smaller in patients with OSA. This is likely due to overregulation of sympathetic activity, which may occur in patients with OSA.

CITATION

Shi Y, Lou H, Wang H, et al. Analysis of nasal resistance regulation mechanism during postural changes in obstructive sleep apnea patients by measuring heart rate variability. J Clin Sleep Med. 2023;19(4):643-650.

Study protocol for randomised clinical trial comparing the effectiveness of side-lying sleep positioning to back-lying at reducing oxygen desaturation resulting from obstructive sleep apnoea in infants with cleft palate (SLUMBRS2)

INTRODUCTION

The craniofacial abnormalities found in infants with cleft palate (CP) decrease their airway patency and increase their risk of obstructive sleep apnoea (OSA). We hypothesise that optimising sleep position in infants with CP may improve airway patency and offer a 'low-cost, high-impact' intervention to prevent the negative impacts of OSA. Because cleft centres give inconsistent advice about sleep position: some recommend back-lying and others side-lying, we will compare these in a randomised controlled trial.

METHODS AND ANALYSIS

The aim is to determine the clinical effectiveness of side-lying as compared with back-lying sleep positioning in terms of reducing oxygen desaturation resulting from OSA in 244 infants aged 3-5 weeks of age, diagnosed with an isolated CP in/by UK cleft centres. Primary outcome is the 4% Oxygen Desaturation Index measured using pulse oximetry during sleep.

RESEARCH PLAN

1. Multicentre randomised controlled trial of side-lying compared with back-lying sleep positioning in reducing oxygen desaturation resulting from OSA in infants with CP at one month of age. 2. Internal pilot questionnaire-based study to support parents and clinicians regarding study participation, seeking to identify and address any barriers to recruitment. Monitoring data from the internal pilot will be used in the final analysis. 3. Co-development of new UK recommendations with Cleft Lip and Palate Association (CLAPA) regarding sleep position for infants with CP.

ETHICS AND DISSEMINATION

The study protocol has received the favourable opinion of the West Midlands-South Birmingham Research Ethics Committee. Study results will be published on affiliated webpages and in peer-reviewed publications and conference contributions.

TRIAL REGISTRATION NUMBER

NCT04478201.

One-minute heart rate variability - an adjunct for airway obstruction identification

Heart rate variability (HRV) reflects cardiac and autonomic nervous system activity. It is usually measured over a relatively prolonged period and presented using multiple parameters. Here, we studied rapid HRV changes during airway obstruction using a short (1 min) sampling window. Forty healthy volunteers underwent a trial of obstructed breathing. Heart rate was recorded during three consecutive sets comprised of 1-min control followed by 1 min of obstructed breathing, with 1 min of rest between sets. Time and frequency domain analysis were used to compare HRV during control versus obstructed breathing. Compared with control, HRV intensely increased during obstructed breathing: R-R intervals (time between consecutive R waves) standard deviation increased from 65 to 108 msec (P < 0.0001), root mean square of successive R-R interval from 61 to 82 msec (P = 0.001), number of pairs of successive R-R intervals that differ by more than 50 msec (NN50) from 16.5 to 25.3 events (P < 0.0001), and proportion of NN50 divided by total number of R-R intervals from 26.6 to 35.1% (P = 0.001). Low frequency power increased by more than fourfold (P < 0.0001), allowing 90% sensitivity and 75% specificity for identifying airway obstruction (ROC area 0.88, P < 0.0001). We observed a rapid intense increase in HRV during obstructed breathing, significant enough to detect during a short 1-min sampling window. These findings suggest that HRV may be useful for rapid detection of airway obstruction, especially in situations where end-tidal CO2 monitoring is not optimal, such as during partial airway obstruction.

The Addition of a Head Rotation When the Ramped Position Fails to Provide Good Laryngeal Visualization: A Preliminary Study

Although several studies have reported that the ramped position (torso and head elevated) significantly improves laryngoscopic view, in our experience, the ramped position fails to provide good laryngeal visualization in some cases. When the ramped position failed to provide good laryngeal visualization, we added a head rotation in order to improve laryngeal visualization in 62 patients. The method significantly improved laryngeal visualization and did not cause laryngeal disturbances postoperatively.

Jaw-thrust induces sympathetic responses during induction of general anesthesia

Background

Jaw-thrust is a noxious stimulus that might induce sympathetic responses. The purpose of this study, was to evaluate the effects of jaw-thrust on sympathetic responses.

Methods

We investigated seventy three patients. Patients who received general anesthesia were randomly divided into a control group (maintenance of combined airway maneuver with head tilt, open mouth by mouthpiece, and chin-lift, n = 30) and jaw-thrust group (maintenance of head tilt, open mouth and jaw-thrust, n = 30). In the jaw-thrust group, four minutes of endoscopy-guided force to the mandible to get the best laryngeal view were applied. For the control group, the combined airway maneuver was maintained during the same period. Arterial blood pressure (AP) and heart rate (HR) were recorded at predetermined time points (1 min before anesthesia induction, 2 min after fiberoptic bronchoscopy placement, and thereafter 1 min-interval during each airway maneuver) during jaw-thrust and chin-lift maneuver. The force amplitude applied for best laryngeal view during jaw-thrust was also measured.

Results

Peak systolic and diastolic AP increased 39.0 ± 17.6 and 39.9 ± 22.8 mmHg from the baseline (P < 0.001) in the jaw-thrust group. HR was also 32.5 ± 19.4 beats/min from the baseline (P < 0.001) in the jaw-thrust group. These remained high at all time points, compared with the control group (P < 0.01). The force magnitude applied for jaw-thrust was not correlated to the AP and HR changes (P > 0.05).

Conclusions

Performing the jaw-thrust maneuver induces significant sympathetic responses, irrespective of the force magnitude.

Effect of head posture on pediatric oropharyngeal structures: implications for airway management in infants and children

PURPOSE OF REVIEW

Although head and neck posture has direct effects on the upper airway in infants and children, many of these effects remain unclear or not well established. As airway patency and airway access are critical in sedated and/or unconscious children, recent developments in this area should be made known to pediatric anesthesiologists, intensive care physicians and other emergency caregivers.

RECENT FINDINGS

All recent studies observed large interindividual variability in anatomical measurements, especially in trachea length. More evidence has been gained that lateral position improves upper airway patency in sedated children. Several studies brought indirect information on head posture for laryngoscopy and intubation.

SUMMARY

The site of obstruction of the airway in sedated children in different postures is now more clear. Implications of head flexion and extension in intubated children have been extensively studied, and clinical consequences have been detailed. Due to large interindividual anatomic variability, depth marks set on the tubes by their manufacturers and guidelines regarding calculations of insertion depth should be made with caution in infants and neonates. Despite several studies, there is still little scientific evidence regarding proper head posture for laryngoscopy and intubation.

Increased heart rate variability correlation between mother and child immediately pre-operation

BACKGROUND

Maternal distress would correlate with the children's mental status, thereby influencing the activity of the autonomic nervous system (ANS) of the children and mothers. We hypothesized that pre-anesthetic maternal ANS activity, when approaching close to their children's operation time, would correlate with children's ANS activity, and that the values of heart rate variability (HRV) would correlate.

METHODS

We calculated maternal and children's HRVs and analyzed the relationship between the two. A total of 24 pairs of mother and child were analyzed. Maternal and children's HRVs were recorded from the night before the child's surgery to the arrival to the operation room.

RESULTS

The ratios of low-frequency components (LF) to high-frequency components (HF) (LF/HF ratio) of children's and maternal HRVs obtained during the immediate pre-operative period (06:00-08:00 hours) showed a significantly, positive correlation, but no correlation was found for the LF/HF ratios obtained during the pre-operative night.

CONCLUSION

The LF/HF ratios of HRV immediately before surgery in children and mothers showed a significant positive correlation.