Hypercapnia impaired cognitive and memory functions in obese patients with obstructive sleep apnoea

Trace of delirium after robotic lower abdominal tumor resection at different end-tidal carbon dioxide: a RCT trial

BACKGROUND

Postoperative delirium (POD) often occurs in oncology patients, further increasing the medical and financial burden. Robotic technology in lower abdominal tumors resection reduces surgical trauma but increases risks such as carbon dioxide (CO2) absorption. This study aimed to investigate the differences in their occurrence of POD at different end-tidal CO2 levels.

METHOD

This study was approved by the Ethics Committee of Affiliated Hospital of He Bei University (HDFY-LL-2022-169). The study was registered with the Chinese Clinical Trials Registry on URL: http://www.chictr.org.cn , Registry Number: ChiCTR2200056019 (Registry Date: 27/08/2022). In patients scheduled robotic lower abdominal tumor resection from September 1, 2022 to December 31, 2022, a comprehensive delirium assessment was performed three days postoperatively using the CAM scale with clinical review records. Intraoperative administration of different etCO2 was performed depending on the randomized grouping after intubation. Group L received lower level etCO2 management (31-40mmHg), and Group H maintained the higher level(41-50mmHg) during pneumoperitoneum. Data were analyzed using Pearson Chi-Square or Wilcoxon Rank Sum tests and multiple logistic regression. Preoperative mental status score, alcohol impairment score, nicotine dependence score, history of hypertension and diabetes, duration of surgery and worst pain score were included in the regression model along with basic patient information for covariate correction analysis.

RESULTS

Among the 103 enrolled patients, 19 (18.4%) developed postoperative delirium. The incidence of delirium in different etCO2 groups was 21.6% in Group L and 15.4% in Group H, respectively, with no statistical differences. In adjusted multivariate analysis, age and during of surgery were statistically significant predictors of postoperative delirium. The breath-hold test was significantly lower postoperatively, but no statistical differences were found between two groups.

CONCLUSION

With robotic assistant, the incidence of postoperative delirium in patients undergoing lower abdominal tumor resection was not modified by different end-tidal carbon dioxide management, however, age and duration of surgery were positively associated risk factors.

The duration-dependent and sex-specific effects of neonatal sevoflurane exposure on cognitive function in rats

Clinical studies have found that neonatal sevoflurane exposure can increase the risk of cognitive dysfunction. However, recent studies have found that it can exhibit neuroprotective effects in some situations. In this study, we aimed to explore the effects of sevoflurane neonatal exposure in rats. A total of 144 rat pups (72 males and 72 females) were assigned to six groups and separately according to sevoflurane exposure of different times on the seventh day after birth. Blood gas analysis and western blot detection in the hippocampus were conducted after exposure. The Morris water maze test was conducted on the 32nd to 38th days after birth. The expression of PSD95 and synaptophysin in the hippocampus was detected after the Morris water maze test. We found that neonatal exposure to sevoflurane promoted apoptosis in the hippocampus, and Bax and caspase-3 were increased in a dose-dependent manner. The 2-h exposure had the greatest effects on cognitive dysfunction. However, with the extension of exposure time to 6 h, the effects on cognitive function were partly compensated. In addition, sevoflurane exposure decreased synaptogenesis in the hippocampus. However, as the exposure time was extended, the suppression of synaptogenesis was attenuated. In conclusion, neonatal sevoflurane exposure exhibited duration-dependent effects on cognitive function via Bax-caspase-3-dependent apoptosis and bidirectional effects on synaptogenesis in rats.

General low alertness in people with obstructive sleep apnea

STUDY OBJECTIVES

In patients with obstructive sleep apnea (OSA), a previous study using a Go/No-Go task reported an average attention deficit. However, the temporal dynamics of such a deficit are unknown. Here, we investigated whether attention deficits in different subdomains increased as the test progressed. We also investigated the effect of target frequency and speed of stimulus presentation on performance.

METHODS

Twenty-seven untreated people with OSA and 27 age- and sex-matched controls underwent a 15-minute Go/No-Go task, divided into 6 blocks. Each block was subdivided into 3 different interstimulus intervals (1, 2, and 4 seconds). Three blocks had a low and three had a high target probability (20% and 80%, respectively). Reaction time (alertness), variability of reaction time (sustained attention), commission errors (response inhibition), and omission errors (focused attention) were measured.

RESULTS

Alertness was lower in the group with OSA compared with controls, as evidenced by a significantly higher average reaction time. This effect was seen from the start of the task and continued until the end but did not increase in test progression. The temporal pattern of intrinsic alertness deficits in patients with OSA was found to be independent of target frequency or interstimulus interval.

CONCLUSIONS

The primary attention problem in OSA is on the alertness subdomain irrespective of the number of required responses or speed of stimulus presentation. The present results support the notion that OSA is distinct from other neurological and psychiatric conditions, such as depression or chronic pain. The results also suggest significant concerns regarding daily life activities (eg, driving).

CITATION

de Souza Bezerra ML, van Duinkerken E, Simões E, Schmidt SL. General low alertness in people with obstructive sleep apnea. J Clin Sleep Med. 2024;20(5):689-698.

Obstructive sleep apnea and cognitive functioning in the older general population: The moderating effect of age, sex, ApoE4, and obesity

Research on the relationship between obstructive sleep apnea and cognitive functioning has yielded conflicting results, particularly in the older population, and moderators of this association have rarely been studied. Here we investigated the cross-sectional association between obstructive sleep apnea and cognitive functioning as well as the moderating effect of age, sex, apolipoprotein E4, and obesity on this association among community-dwelling older people. We analysed data from 496 participants (71.4 ± 4.4 years; 45.6% men) of the HypnoLaus study who underwent polysomnography and a battery of neuropsychological tests. The sample was categorised as no-to-mild obstructive sleep apnea (apnea-hypopnea index 0-14.9/h; reference), moderate obstructive sleep apnea (apnea-hypopnea index 15.0-29.9/h), or severe obstructive sleep apnea (apnea-hypopnea index ≥30/h). Regression and moderation analyses were performed with adjustment for confounders. Apolipoprotein E4 and obesity moderated the association between severe obstructive sleep apnea and processing speed, whereas no moderating effects were found for age and sex. In apolipoprotein E4 carriers only, severe obstructive sleep apnea was associated with lower performance in Stroop condition 1 (B = 3.13, p = 0.024). In obese participants only, severe obstructive sleep apnea was associated with lower performance in Stroop condition 1 (B = 3.02, p = 0.025) and Stroop condition 2 (B = 3.30, p = 0.034). Severe obstructive sleep apnea was also associated with lower executive function in the whole sample according to Stroop condition 3 (B = 3.44, p = 0.020) and Stroop interference score (B = 0.24, p = 0.006). Our findings support associations of severe obstructive sleep apnea (but not moderate obstructive sleep apnea) with lower performance in processing speed and executive function in the older general population. Apolipoprotein E4 and obesity appear to be vulnerability factors that strengthen the association between severe obstructive sleep apnea and lower performance in processing speed.

Cognitive Functions in Patients with Moderate-to-Severe Obstructive Sleep Apnea Syndrome with Emphasis on Executive Functions and Decision-Making

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) have cognitive dysfunction in many aspects, however, these patients' decision-making function remains unclear. In this study, the Game of Dice Task (GDT) was used to investigate the function of decision making in patients with OSAS.

METHODS

30 participants with moderate to severe OSAS and 27 participants with no or mild OSAS diagnosed by sleep breathing monitor were selected from June 2021 to March 2022. Risky decision making was tested through the GDT with known risk probability. General demographic information and background cognitive functions, such as the overall cognitive functioning and executive functioning, were tested to establish baseline data.

RESULTS

There were no significant differences in gender, age, and years of education between the two groups. During the GDT, the moderate to severe OSAS group opted for the safety option at a statistically significant lower rate when compared to the no or mild OSAS group (7.53 ± 4.43 vs. 10.26 ± 4.26, p = 0.022). The moderate to severe OSAS group utilized the higher risk option than the group with no or mild OSAS (10.47 ± 4.43 vs. 7.74 ± 4.26, p = 0.022). The utilization rate of negative feedback in the moderate and severe OSAS group was lower than that in the no or mild OSAS group (7.50, 52.50 vs. 28.57, 100.00, p = 0.001). At the end of the GDT, the moderate and severe OSAS group was more likely to have negative total assets than the patients with no or mild OSAS (-1846.67 ± 2587.20 vs. 300.00 ± 1509.97, p < 0.001). Multiple linear regression analysis shows that there is a negative correlation between the selection of risk options and negative feedback utilization in the GDT.

CONCLUSION

Patients with moderate and severe OSAS displayed impaired decision-making throughout the study. Impaired decision-making is related to executive processes and may be caused by diminished prefrontal cortex functioning. However, the functions of memory, attention, language, abstraction, and orientation are relatively retained.

Neuropsychiatric Outcomes and Sleep Dysfunction in COVID-19 Patients: Risk Factors and Mechanisms

The ongoing global health crisis due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has significantly impacted all aspects of life. While the majority of early research following the coronavirus disease caused by SARS-CoV-2 (COVID-19) has focused on the physiological effects of the virus, a substantial body of subsequent studies has shown that the psychological burden of the infection is also considerable. Patients, even without mental illness history, were at increased susceptibility to developing mental health and sleep disturbances during or after the COVID-19 infection. Viral neurotropism and inflammatory storm damaging the blood-brain barrier have been proposed as possible mechanisms for mental health manifestations, along with stressful psychological factors and indirect consequences such as thrombosis and hypoxia. The virus has been found to infect peripheral olfactory neurons and exploit axonal migration pathways, exhibiting metabolic changes in astrocytes that are detrimental to fueling neurons and building neurotransmitters. Patients with COVID-19 present dysregulated and overactive immune responses, resulting in impaired neuronal function and viability, adversely affecting sleep and emotion regulation. Additionally, several risk factors have been associated with the neuropsychiatric sequelae of the infection, such as female sex, age, preexisting neuropathologies, severity of initial disease and sociological status. This review aimed to provide an overview of mental health symptoms and sleep disturbances developed during COVID-19 and to analyze the underlying mechanisms and risk factors of psychological distress and sleep dysfunction.

The effect of intraoperative transnasal humidified rapid-insufflation ventilatory exchange on emergence from general anesthesia in patients undergoing microlaryngeal surgery: a randomized controlled trial

BACKGROUND

Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) has received extensive attention for its utility in tubeless anesthesia. Still, the effects of its carbon dioxide accumulation on emergence from anesthesia have not been reported. This randomized controlled trial aimed at exploring the impact of THRIVE combined with laryngeal mask (LM) on the quality of emergence in patients undergoing microlaryngeal surgery.

METHODS

After research ethics board approval, 40 eligible patients receiving elective microlaryngeal vocal cord polypectomy were randomly allocated 1:1 to two groups, THRIVE + LM group: intraoperative apneic oxygenation using THRIVE followed by mechanical ventilation through a laryngeal mask in the post-anesthesia care unit (PACU), or MV + ETT group: mechanically ventilated through an endotracheal tube for both intraoperative and post-anesthesia periods. The primary outcome was duration of PACU stay. Other parameters reflecting quality of emergence and carbon dioxide accumulation were also recorded.

RESULTS

Duration of PACU stay (22.4 ± 6.4 vs. 28.9 ± 8.8 min, p = 0.011) was shorter in the THRIVE + LM group. The incidence of cough (2/20, 10% vs. 19/20, 95%, P < 0.001) was significantly lower in the THRIVE + LM group. Peripheral arterial oxygen saturation and mean arterial pressure during intraoperative and PACU stay, Quality of Recovery Item 40 total score at one day after surgery and Voice Handicap Index-10 score at seven days after surgery were of no difference between two groups.

CONCLUSIONS

The THRIVE + LM strategy could accelerate emergence from anesthesia and reduce the incidence of cough without compromising oxygenation. However, these benefits did not convert to the QoR-40 and VHI-10 scores improvement.

TRIAL REGISTRATION

ChiCTR2000038652.

A retrospective study of the role of hypercapnia in patients with acromegaly

BACKGROUND

Acromegaly is a multisystemic disease characterized by an excessive release of growth hormone (GH) and insulin-like growth factor-1. Obstructive sleep apnea (OSA) is a common consequence of acromegaly, and hypercapnia is frequently observed in patients with acromegaly, OSA, and obesity. However, the effects of hypercapnia on acromegaly remain unknown. This study was designed to investigate whether there are differences in clinical symptoms, sleep variables, and biochemical remission after surgery for acromegaly in patients with OSA with or without hypercapnia.

METHODS

A retrospective analysis was conducted involving patients with acromegaly and OSA. The pharmacotherapy history for acromegaly before surgery, anthropometric measures, blood gas, sleep monitoring data, and biochemical assays of hypercapnic and eucapnic individuals were collected 1-2 weeks before surgery. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for failed postoperative biochemical remission.

RESULTS

In this study, 94 patients with OSA and acromegaly were included. Among them, 25 (26.6%) had hypercapnia. The hypercapnic group had higher body mass index (92% vs. 62.3%; p = 0.005) and poorer nocturnal hypoxemia index. No serological differences were found between the two groups. According to the post-surgery GH level, 52 patients (55.3%) reached biochemical remission. Univariate logistic regression analysis revealed that diabetes mellitus (odds ratio [OR], 2.59; 95% confidence interval [CI], 1.02-6.55), instead of hypercapnia (OR, 0.61; 95% CI, 0.24-1.58), was associated with lower remission rates. Patients who received pharmacotherapy for acromegaly before surgery (OR, 0.21; 95% CI, 0.06-0.79) and had higher thyroid-stimulating hormone levels (OR, 0.53; 95% CI, 0.32-0.88) were more likely to have biochemical remission after surgery. Multivariate analysis further showed that only diabetes mellitus (OR, 3.29; 95% CI, 1.15-9.46) and preoperative pharmacotherapy (OR, 0.21; 95% CI, 0.06-0.83) remained significant. Hypercapnia, hormone levels, and sleep indicators had no effect on biochemical remission after surgery.

CONCLUSIONS

Single-center evidence shows that hypercapnia alone may not be a risk factor for lower biochemical remission rates. Correcting hypercapnia does not appear to be required before surgery. More evidence is needed to further support this conclusion.

Daytime Hypercapnia Impairs Working Memory in Young and Middle-Aged Patients with Obstructive Sleep Apnea Hypopnea Syndrome

Purpose

Obstructive sleep apnea hypopnea syndrome (OSAHS) can lead to cognitive impairment, though few studies have so far examined hypercapnia as its causal mechanism, due to the invasive nature of conventional arterial CO2 measurement. The study aims to investigate the effects of daytime hypercapnia on working memory in young and middle-aged patients with OSAHS.

Patients and Methods

This prospective study screened 218 patients and eventually recruited 131 patients (aged 25-60 years) with polysomnography (PSG)-diagnosed OSAHS. Using a cut-off of 45mmHg daytime transcutaneous partial pressure of carbon dioxide (PtcCO2), 86 patients were assigned into the normocapnic group and 45 patients into the hypercapnic group. Working memory was evaluated using the Digit Span Backward Test (DSB) and the Cambridge Neuropsychological Test Automated Battery.

Results

Compared with the normocapnic group, the hypercapnic group performed worse in verbal, visual, and spatial working memory tasks. PtcCO2≥45mmHg was an independent predictor for lower DSB scores (OR=4.057), lower accuracy in the immediate Pattern Recognition Memory (OR=2.600), delayed Pattern Recognition Memory (OR=2.766) and Spatial Recognition Memory (OR=2.722) tasks, lower Spatial Span scores (OR=4.795), and more between errors in the Spatial Working Memory task (OR=2.734 and 2.558, respectively). Notably, PSG indicators of hypoxia and sleep fragmentation did not predict task performance.

Conclusion

Hypercapnia may be plays an important role in working memory impairment in patients with OSAHS, perhaps more so than hypoxia and sleep fragmentation. Routine CO2 monitoring in these patients could prove of utility in clinical practices.

Continuous positive airway pressure improved daytime sleepiness and memory function in patients with obstructive sleep apnea

Objectives

Obstructive sleep apnea (OSA) is a sleep disorder which results in daytime sleepiness and impaired memory function. The aim of this study was to investigate the effect of continuous positive airway pressure (CPAP) on daytime sleepiness and memory function in OSA patients. We also investigated whether CPAP compliance impacted the effect of this treatment.

Materials and Methods

The nonrandomized, nonblinded clinical trial enrolled 66 patients with moderate-to-severe OSA subjects. All subjects completed a polysomnographic study, daytime sleepiness questionnaires (the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index), and four memory function tests (working memory; processing speed [PS]; logical memory [LM]; face memory [FM]).

Results

Before CPAP treatment, no significant differences (P < 0.05) were noted in the demographic data, daytime sleepiness, or memory function between two groups (with/without CPAP). However, OSA patients treated with CPAP for 2 months showed significant improvements in daytime sleepiness, PS, mostly of LM, and FM comparing to 2 months ago. As compared to those who did not receive CPAP treatment, CPAP can improve only parts of LM (delayed LM [DLM] and LM percentage [LMP]). In addition, compared to control group, a significant improvement of daytime sleepiness and LM (LM learning, DLM, and LMP) in good compliance with CPAP treatment group and of DLM and LMP in the low compliance with CPAP treatment group was found.

Conclusion

CPAP treatment for 2 months could improve some of LM in OSA patients, especially in patients exhibiting good CPAP compliance.

Contribution of hypercapnia to cognitive impairment in severe sleep-disordered breathing

STUDY OBJECTIVES

Although cognitive impairment in obstructive sleep apnea (OSA) is primarily attributed to intermittent hypoxemia and sleep fragmentation, hypercapnia may also play a role in patients whose OSA is complicated by hypoventilation. This study investigated the impact of hypercapnia on cognitive function in severe sleep-disordered breathing (OSA accompanied by hypoventilation).

METHODS

Patients with severe OSA (apnea-hypopnea index >30 events/h; n = 246) underwent evaluation for accompanying hypoventilation with polysomnography that included continuous transcutaneous carbon dioxide (TcCO₂) monitoring and awake arterial blood gas analysis. Patients were categorized as having no hypoventilation (n = 84), isolated sleep hypoventilation (n = 40), or awake hypoventilation (n = 122). Global cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA), memory with the Rey Auditory Verbal Learning Test (RAVLT), and processing speed with the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV), Digit Symbol Coding subtest (DSC).

RESULTS

Apnea-hypopnea index was similar across groups (P = .15), but the sleep and awake hypoventilation groups had greater nocturnal hypoxemia compared with the no-hypoventilation group (P < .01). Within all groups, mean MoCA scores were < 26, which is the validated threshold to indicate mild cognitive impairment; RAVLT scores were lower than age-matched norms only in the awake-hypoventilation group (P ≤ .01); and DSC scores were lower than age-matched norms within all groups (P < .01). In multivariable regression analyses, higher arterial partial pressure of carbon dioxide (PaCO₂) and TcCO₂ during wakefulness were associated with lower MoCA and DSC scores (P ≤ .03), independent of confounders including overlap syndrome (OSA + chronic obstructive pulmonary disease).

CONCLUSIONS

Awake hypoventilation is associated with greater deficits in cognitive function in patients with severe sleep-disordered breathing.

CITATION

Beaudin AE, Raneri JK, Ayas NT, Skomro RP, Smith EE, Hanly PJ; on behalf of Canadian Sleep and Circadian Network. Contribution of hypercapnia to cognitive impairment in severe sleep-disordered breathing. J Clin Sleep Med. 2022;18(1):245-254.

Neurological effects of respiratory dysfunction

The respiratory and the nervous systems are closely interconnected and are maintained in a fine balance. Central mechanisms maintain strict control of ventilation due to the high metabolic demands of brain which depends on a continuous supply of oxygenated blood along with glucose. Moreover, brain perfusion is highly sensitive to changes in the partial pressures of carbon dioxide and oxygen in blood, which in turn depend on respiratory function. Ventilatory control is strictly monitored and regulated by the central nervous system through central and peripheral chemoreceptors, baroreceptors, the cardiovascular system, and the autonomic nervous system. Disruption in this delicate control of respiratory function can have subtle to devastating neurological effects as a result of ensuing hypoxia or hypercapnia. In addition, pulmonary circulation receives entire cardiac output and this may act as a conduit to transmit infections and also for metastasis of malignancies to brain resulting in neurological dysfunction. Furthermore, many neurological paraneoplastic syndromes can have underlying lung malignancies resulting in respiratory dysfunction. It is essential to understand the underlying mechanisms and the resulting manifestations in order to prevent and effectively manage the many neurological effects of respiratory dysfunction. This chapter explores the various neurological effects of respiratory dysfunction with focus on their pathophysiology, etiologies, clinical features and long-term neurological sequelae.

Hypoxemia following hospital discharge after fast-track hip and knee arthroplasty - A prospective observational study subanalysis

BACKGROUND

Post-operative hypoxemia is prevalent in hospitalized patients and may adversely affect recovery. However, little data exist on the post-discharge phase or details on duration, severity and potential risk factors. Thus, we investigated the incidence and risk factors for severe desaturation during the first post-operative week after THA/TKA by continuous nocturnal oxygen saturation monitoring.

METHODS

The study was a secondary analysis of a prospective cohort study of 112 patients undergoing fast-track THA/TKA. Patients with known sleep apnoea were excluded. Oxygen saturation and heart rate were recorded by a wireless wrist-worn pulse oximeter 2 nights before and 7 nights after surgery. Data on demographics, opioid consumption and cognitive function were collected from medical charts, patient diaries and clinical testing respectively. The primary outcome was occurrence of severe desaturation defined as periods with saturation <85% lasting ≥10 minutes. Secondary outcomes included description of various saturation levels and relevant risk factors.

RESULTS

Severe oxygen desaturation occurred in 35% of the patients during the first post-operative week. Duration and severity of hypoxemic episodes increased after the first post-operative day. Pre-operative episodes of hypoxemia significantly increased the risk of post-operative hypoxemic events (OR 2.4-4.4, CI 0.4-46), while pre- and post-operative opioid use, age, gender, ASA classification, type of surgery or anaesthesia were significantly related to the development of post-operative hypoxemia.

CONCLUSIONS

One third of the patients suffered from increased and prolonged episodes of severe nocturnal hypoxemia during the first week after THA/TKA discharge. Increased risk for severe hypoxemic episodes was related to pre-operative hypoxemia.

Associations between hypoxia parameters in obstructive sleep apnea and cognition, cortical thickness, and white matter integrity in middle-aged and older adults

OBJECTIVE

This study aimed to investigate the association between each parameter of intermittent hypoxia in obstructive sleep apnea (OSA) and the cognitive profile, cortical thickness, and white matter integrity in middle-aged and older adults.

METHODOLOGY

Participants were newly diagnosed with moderate or severe OSA from the King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Respiratory parameters from polysomnography were extracted. Each participant was tested on a battery of neuropsychological tests and underwent an MRI scan of the brain. Cortical thickness analysis and diffusion tensor imaging analysis were performed. Participants were classified as having either severe or mild hypoxia based on parameters of hypoxia, i.e., oxygen desaturation index, lowest oxygen saturation, and the percentage of total sleep time spent below 90% oxygen saturation.

RESULTS

Of 17 patients with OSA, there were 8 men (47%). Median age was 57 years and median AHI was 60.6. Comparison of cortical thickness between the severe and the mild group of each hypoxic parameter revealed two clusters of cortical thinning at the right inferior frontal gyrus (p-value = 0.008) and right inferior parietal gyrus (p-value = 0.006) in the severe desaturation group and a cluster of cortical thinning at the superior parietal gyrus (p-value = 0.008) in the high oxygen desaturation index group. There was no difference in cognitive function or white matter integrity between groups.

CONCLUSIONS

The magnitude of the degree and frequency of desaturations in OSA are associated with a decrease in cortical thickness at the frontal and parietal regions.

Vasomotor influences on glymphatic-lymphatic coupling and solute trafficking in the central nervous system

Despite the recent description of meningeal lymphatic vessels draining solutes from the brain interstitium and cerebrospinal fluid (CSF), the physiological factors governing cranial lymphatic efflux remain largely unexplored. In agreement with recent findings, cervical lymphatic drainage of 70 kD and 2000 kD fluorescent tracers injected into the adult mouse cortex was significantly impaired in the anesthetized compared to waking animals (tracer distribution across 2.1 ± 4.5% and 23.7 ± 15.8% of deep cervical lymph nodes, respectively); however, free-breathing anesthetized mice were markedly hypercapnic and acidemic (paCO₂ = 64 ± 8 mmHg; pH = 7.22 ± 0.05). Mechanical ventilation normalized arterial blood gases in anesthetized animals, and rescued lymphatic efflux of interstitial solutes in anesthetized mice. Experimental hypercapnia blocked cervical lymphatic efflux of intraparenchymal tracers. When tracers were injected into the subarachnoid CSF compartment, glymphatic influx into brain tissue was virtually abolished by hypercapnia, while lymphatic drainage was not appreciably altered. These findings demonstrate that cervical lymphatic drainage of interstitial solutes is, in part, regulated by upstream changes in glymphatic CSF-interstitial fluid exchange. Further, they suggest that maintaining physiological blood gas values in studies of glymphatic exchange and meningeal lymphatic drainage may be critical to defining the physiological regulation of these processes.

The relationship between inflammation and neurocognitive dysfunction in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS), a state of sleep disorder, is characterized by repetitive apnea, chronic hypoxia, oxygen desaturation, and hypercapnia. Previous studies have revealed that intermittent hypoxia (IH) conditions in OSAS patients elicited neuron injury (especially in the hippocampus and cortex), leading to cognitive dysfunction, a significant and extraordinary complication of OSAS patients. The repeated courses of airway collapse and obstruction in OSAS patients resulted in apnea and arousal during sleep, leading to IH and excessive daytime sleepiness (EDS) and subsequently contributing to the development of inflammation. IH-mediated inflammation could further trigger various types of cognitive dysfunction. Many researchers have found that, besides continuous positive airway pressure (CPAP) treatment and surgery, anti-inflammatory substances might alleviate IH-induced neurocognitive dysfunction. Clarifying the role of inflammation in IH-mediated cognitive impairment is crucial for potentially valuable therapies and future research in the related domain. The objective of this article was to critically review the relationship between inflammation and cognitive deficits in OSAS.

Effect of Sleep Disorder on Delirium in Post-Cardiac Surgery Patients

BACKGROUND

Post-cardiac surgery patients exhibit a higher incidence of postoperative delirium (PD) compared to non-cardiac surgery patients. Patients with various cardiac diseases suffer from preoperative sleep disorder (SPD) induced by anxiety, depression, breathing disorder, or other factors.

OBJECTIVE

To examine the effect of sleep disorder on delirium in post-cardiac surgery patients.

METHODS

We prospectively selected 186 patients undergoing selective cardiac valve surgery. Preoperative sleep quality and cognitive function of all eligible participants were assessed through the Pittsburgh Sleep Quality Index (PSQI) and the Montreal Cognitive Assessment, respectively. The Confusion Assessment Method for Intensive Care Unit was used to assess PD from the first to seventh day postoperatively. Patients were divided into two groups according to the PD diagnosis: (1) No PD group and (2) the PD group.

RESULTS

Of 186 eligible patients, 29 (15.6%) were diagnosed with PD. A univariate analysis showed that gender (p = 0.040), age (p = 0.009), SPD (p = 0.008), intraoperative infusion volume (p = 0.034), postoperative intubation time (p = 0.001), and intensive care unit stay time (p = 0.009) were associated with PD. A multivariate logistic regression analysis demonstrated that age (odds ratio (OR): 1.106; p = 0.001) and SPD (OR: 3.223; p = 0.047) were independently associated with PD. A receiver operating characteristic curve demonstrated that preoperative PSQI was predictive of PD (area under curve: 0.706; 95% confidence interval: 0.595-0.816). A binomial logistic regression analysis showed that there was a significant association between preoperative 6 and 21 PSQI scores and PD incidence (p = 0.009).

CONCLUSIONS

Preoperative SPD was significantly associated with PD and a main predictor of PD.