Apnea Duration Research Articles

Voltage Stimulation of the Anterior Ethmoidal Nerve in Rats Produces a Cardiorespiratory Response Similar to the Diving Response

The diving response, initiated when animals submerge under water, includes a decrease in heart rate, peripheral vasoconstriction, and apnea. Electrical stimulation of the anterior ethmoidal nerve (AEN), the nerve that innervates the nasal passages, can produce similar reflex responses. The purpose of the present research in Sprague‐Dawley rats was to electrically stimulate the AEN using silver coated copper wire and a voltage stimulus supplied through an iWorx TA‐220 Control Module and Labscribe software. Our hypothesis was that increasing the intensity of the AEN electrical stimulation would increase the intensity of the resultant cardiorespiratory responses. Accordingly, we isolated the AEN at the base of the orbit, hooked the electrodes around the nerve, and insulated the nerve and orbit with dental impression material. While recording heart rate, arterial blood pressure and respiration, we varied 5 s of AEN electrical stimulation between 0.1 and 1.1 volts. Stimulation threshold of 0.2 volts would elicit slight bradycardia, slight alterations in BPa, and a slight decrease in respiratory rate. With increasing voltages, the response intensified. When maximally stimulated, HR decreased from 438 ± 28 to 181 ± 37 bpm, and BPa decreased from 127 ± 5 to 121 ± 14 mmHg. The respiratory rate decreased from 93 ± 3 to 0 breaths/min with an apnea duration of 5.0 ± 0.2 s. Our studies found that the intensity of the cardiorespiratory responses and the voltage of the AEN stimulation varied somewhat linearly. This technique and these findings can be used in future research to investigate the brainstem pathways of the mammalian diving response.

Unilateral Vagotomy Blunts Cardiorespiratory Responses to Vagal Afferent Stimulation and Nucleus Tractus Solitarii (NTS) Glutamate Microinjection

The nTS of the brainstem is the initial integration site of sensory information from the cardiorespiratory system, including afferents from the vagus nerve carrying input from the heart and lungs. The nTS is an important site of neuroplasticity, which depends on factors including neuronal and astrocytic activity, with the latter regulating glutamate (Glu) signaling. We have shown that unilateral transection of the vagus nerve to decrease afferent input results in morphologic changes in nTS glia. Vagal nerve transection also decreases nTS synaptic transmission studied in vitro. The influence of vagotomy on in vivo cardiorespiratory function via afferent‐driven Glu signaling is unknown. We hypothesized that chronic vagotomy blunts cardiorespiratory responses to vagal afferent stimulation via decreased Glu signaling. Male Sprague‐Dawley rats (6‐wk, N=19) were randomly assigned to vagotomy or sham groups. Right cervical vagus nerve transection caudal to the nodose ganglion or sham surgery was performed. One week after surgery, rats were anesthetized, ventilated, and instrumented to measure mean arterial pressure (MAP), heart rate (HR), splanchnic sympathetic and phrenic nerve activity (SSNA and PhrNA, respectively). Intact vagus nerves were transected acutely to prevent efferent stimulation. Left and right vagus nerves were stimulated (20 sec, 0.2mA, 2‐10Hz, 0.5ms pulse width) and responses recorded for 3 minutes. Chronic vagotomy had no effect on baseline cardiorespiratory parameters compared to shams. Vagal nerve stimulation on either side increased MAP, HR, and SSNA and decreased PhrNA in all groups. There were no consistent group differences in MAP, HR, and SSNA responses. However, chronic vagotomy blunted the stimulation‐induced decrease in PhrNA frequency and amplitude and decreased apnea duration on the ipsilateral side compared to contralateral stimulation and to shams. To evaluate the mechanism of altered respiratory responses, Glu was nanoinjected (30nL, 1‐10mM) into the left and right nTS of chronic vagotomy and sham rats. Glu decreased MAP, HR, SSNA, and PhrNA in all groups and on both sides. Chronic vagotomy had minimal effects on MAP and SSNA responses, but blunted the decrease in HR and PhrNA frequency and amplitude during ipsilateral Glu injection compared to contralateral. The blunted responses to vagal afferent stimulation and nTS glutamate suggest that chronic vagotomy alters Glu signaling in part via postsynaptic mechanisms. Additional experiments are needed to determine the mechanisms (including the role of astrocytes) of altered nTS Glu signaling to changes in afferent input in cardiorespiratory health and disease.

Body fat levels and its negative correlation to apnea duration

Apnea ability is the main determining factor of freediving performance. Apnea relates to physiological factors that might be experienced by a free diver hence its ability is highly likely to correlate with various factors of human physiology. One of the suspected factors that affect apnea duration is body fat level. The fact that fat is distributed in almost all parts of the body, including respiratory organs and tracts, arises the suspicion of a possible correlation between fat accumulation and apnea ability. This research studies the correlation between body fat level and apnea duration. 30 males, aged 18-22 were the research participant. Body fat levels were measured using Bioelectrical Impedance Analyzer, while apnea duration was measured by the length of which the participants hold their breath while sitting silently in the pool. The obtained data were then analyzed using a series of tests: normality, correlation, and linear regression tests. Pearson Correlation test shows negative result (p0,05) with the value of correlation coefficient -0.611 which means negative correlation with medium strength. The result of the linear regression test also shows a similar value of 0.611. Meanwhile, the value of the determinant coefficient (R square) is 0.374 (37.4%). Based on the value obtained, it can be inferred that body fat levels have 37.4% influence on the duration of apnea, while the other 62.2% are influenced by a variety of other factors

Association of insomnia and short sleep duration, alone or with comorbid obstructive sleep apnea, and the risk of chronic kidney disease.

Obstructive sleep apnea (OSA), sleep fragmentation, and short sleep duration (SD) have been associated with chronic kidney disease (CKD). However, these potential mechanisms for CKD have not been compared in the same cohort. This study investigated the independent and combined impact of OSA and insomnia with short sleep duration on the risk of CKD progression in a sleep clinic population. In a cross-sectional study design, adults with suspected OSA completed an overnight sleep study and a questionnaire that included the Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI). They also provided blood and urine samples for measurement of the glomerular filtration rate and urine albumin:creatinine ratio, from which the risk of CKD progression was determined. Participants (n = 732, 41% female, 55 ± 13 years) were categorized into four groups: no/mild OSA without insomnia (NM-OSA, n = 203), insomnia with SD without OSA (Insomnia-SD, n = 104), moderate-to-severe OSA without insomnia (MS-OSA, n = 242), and comorbid insomnia and OSA with SD (COMISA-SD, n = 183). After stratification, 12.8% of NM-OSA, 15.4% of Insomnia-SD, 28.9% of MS-OSA, and 31.7% of the COMISA-SD participants had an increased risk of CKD progression. Compared to NM-OSA, the odds ratio (OR) for an increased risk of CKD progression was not increased in Insomnia-SD (OR 0.95, confidence interval [CI]: 0.45-1.99) and was increased to the same degree in MS-OSA (OR 2.79, CI: 1.60-4.85) and COMISA-SD (OR 3.04, CI: 1.69-5.47). However, the ORs were similar between the MS-OSA and COMISA-SD groups across all statistical models (p ≥ .883). In a sleep clinic population, insomnia with short sleep duration does not increase the risk of CKD progression; nor does it further increase the risk of CKD progression associated with moderate-to-severe OSA.

Relationships between quality of life, sleep problems, and sleep quality in patients with chronic idiopathic urticaria.

In this study, we aimed to evaluate the sleep quality among chronic urticaria patients using the Chronic Urticaria Quality-of-Life Questionnaire (CU-Q2oL), sleep quality assessment tools, and polysomnography and to investigate any relationships between the obtained results. The study included 21 patients diagnosed with chronic spontaneous urticaria and 19 healthy controls. We recorded the patients' sleep quality data, including CU-Q2 oL, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and polysomnography results. Patients in the chronic urticaria group were more likely to have an ESS score of ≥10 (52.4% vs. 5.3%, p=0.004) and an apnea-hypopnea index of ≥5 (44.4% vs. 5.3%, p=0.017) compared to the control group. In the patient group, the CU-Q2 oL total score was positively correlated with sleep latency (r=0.713, p=0.004) and PSQI-C1 score (r=0.726, p=0.005), while it was negatively correlated with urticaria duration (r=-0.579, p=0.015), apnea-hypopnea index (r=-0.607, p=0.021), longest apnea duration (r=-0.583, p=0.029), total number of respiratory events (r=-0.618, p=0.018), and apnea count (r=-0.686, p=0.007). We conclude that sleep-related problems exist among a considerably large proportion of patients with chronic spontaneous urticaria.

Gamma Power of Electroencephalogram Arousal Is Modulated by Respiratory Event Type and Severity in Obstructive Sleep Apnea.

We aimed to investigate the differences in electroencephalogram (EEG) gamma power (30-40 Hz) of respiratory arousals between varying types and severities of respiratory events, and in different sleep stages. Power spectral densities of EEG signals from diagnostic Type I polysomnograms of 869 patients with clinically suspected obstructive sleep apnea were investigated. Arousal gamma powers were compared between sleep stages, and between the type (obstructive apnea and hypopnea) and duration (10-20 s, 20-30 s, and >30 s) of the related respiratory event. Moreover, we investigated whether the presence of a ≥3% blood oxygen desaturation influenced the arousal gamma power. Gamma power of respiratory arousals was the lowest in Stage R sleep and increased from Stage N1 towards Stage N3. Gamma power was higher when the arousals were caused by obstructive apneas compared to hypopneas. Moreover, arousal gamma power increased when the duration of the related apnea increased, whereas an increase in the hypopnea duration did not have a similar effect. Furthermore, respiratory events associated with desaturations increased the arousal gamma power more than respiratory events not associated with desaturations. Gamma power of respiratory arousals increased towards deeper sleep and as the severity of the related respiratory event increased in terms of type and duration of obstruction, and presence of desaturation. As increased gamma power might indicate a greater shift towards wakefulness, the present findings demonstrate that the respiratory arousal intensity and the magnitude of sleep disruption may vary depending on the event type and severity.

Effect of Opium Versus Methadone on Polysomnographic Characteristics of Patients With Obesity Hypoventilation Syndrome.

There are studies about polysomnographic (PSG) characteristics of patients with either obesity hypoventilation syndrome (OHS) or addiction. We aimed to investigate the PSG characteristics of obstructive sleep apnea (OSA) patients with opium addiction, those on methadone maintenance treatment (MMT), and non-addicts for the treatment of addiction. In this cross-sectional study, we enrolled 75 patients with OHS in the Bamdad Respiratory and Sleep Research Center affiliated with the Isfahan University of Medical Sciences between January 2020 and February 2021. The patients were categorized into three groups: Opium addicts (OA), MMT, and non-addicts (NA). All patients completed screening questionnaires for OSA. This included the Epworth sleepiness scale (ESS), stop-bang questionnaire, and Berlin questionnaire and the data analyzed by SPSS software, version 24. A total of 75 OHS patients (54 men [72%] and 21 women [28%]) were studied in three groups, including OA (n=30), MMT (n=15), and NA (n=30). The apnea hypopnea index was not significantly different between the three groups. The longest apnea duration was higher in the OA than in other groups (P=0.001). Central apnea index (P=0.01), longest hypopnea duration (P=0.04), PaCO2 (P=0.04), and time with SpO2<90% (T90) (P=0.009) were higher in the MMT than in other groups. Furthermore, the minimum SpO2 was lower in the MMT than in other groups (P=0.03). Some of the sleep disturbances were worse in the MMT than in the OA group. This suggests the need for further studies to compare the effects of opium and methadone on sleep in OHS patients.

Submillisievert CT chest for COVID-19 patients in a rural hospital with limited resources

BackgroundThis is a secondary analysis of prospectively acquired data approved by the hospital institutional board committee. We performed a retrospective chart review of 463 patients who underwent a CT Chest for suspected COVID-19 infection between April 1st, 2020, and March 31st, 2021. Patients were grouped based on the CT chest obtained protocol: ultra-low dose or full dose. The likelihood of suspicion of COVID-19 infection was classified on a Likert scale based on the probability of pulmonary involvement. For each group, the sensitivity and specificity of CT were compared to nasopharyngeal swab as standard of reference. The median dose length product and duration of apnea were compared between both groups using two-tailed Mann–Whitney U test. The aim of this study is to share our experience of reducing radiation dose in COVID-19 patients by using an ultra-low dose CT chest protocol on a 16 row multidetector CT scan in a hospital with limited resources.ResultsTwo hundred sixty-nine patients underwent a full dose CT and 194 patients an ultra-low dose CT. In the former group, the median dose length product was 341.11 mGy*cm [Interquartile range (IQR), 239.1–443.2] and the median duration of apnea was 13.29 s [IQR, 10.85–15.73]. In the latter group, the median dose length product was 30.8 mGy*cm [IQR, 28.9–32.7] and median duration of apnea was 8.27 s [IQR, 7.69–8.85]. The sensitivity of the ultra-low dose CT was 91.2% and that of the full dose was 94%.ConclusionA 90% reduction in estimated dose and 38% reduction in apnea duration could be achieved using an ultra-low dose CT chest protocol on a 16-row MDCT without significant loss in the sensitivity of CT to detect COVID-related parenchymal involvement.

Pitfalls of AHI system of severity grading in obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is the major underlying co-morbidity in many of the non-communicable diseases (NCD) due to obesity as a common risk factor. Incidence and prevalence of OSA is on the constant rise ever since this entity came to forefront three decades ago. Precise treatment of underlying OSA is extremely important in major NCDs like diabetes mellitus, hypertension, endocrine disorders and vascular diseases. OSA is subcategorized in to mild, moderate and severe based of apnoea-hypopnea index (AHI). Based on the severity grading, treatment of OSA ranges from life style modifications to oral appliances, continuous positive airway pressure (CPAP) and surgeries. AHI system of severity grading in OSA has several inherent shortcomings and using AHI system for severity grading as the holy grail is likely to be counter-productive. AHI system equates apnoea and hypopnea as equal events, whereas physiological effects vary significantly. AHI system does not account duration of apnoea or body position during apnoeic events. We discuss at length the pitfalls of AHI system of severity grading in OSA.

Brain Injury Effects on Neuronal Activation and Synaptic Transmission in the Basolateral Amygdala of Adult Male and Female Wistar Rats.

Traumatic brain injury (TBI) is defined as brain damage produced by an external mechanical force that leads to behavioral, cognitive, and psychiatric sequelae. The basolateral amygdala (BLA) is involved in emotional regulation, and its function and morphology are altered following TBI. Little is known about potential sex-specific effects of TBI on BLA neuronal function, but it is critical for the field to identify potential sex differences in TBI effects on brain and behavior. Here, we hypothesized that TBI would produce sex-specific acute (1 h) effects on BLA neuronal activation, excitability, and synaptic transmission in adult male and female rats. Forty-nine Wistar rats (n = 23 males and 26 females) were randomized to TBI (using lateral fluid percussion) or Sham groups in two separate studies. Study 1 used in situ hybridization (i.e., RNAscope) to measure BLA expression of c-fos (a marker of cell activation), vGlut, and vGat (markers of glutamatergic and GABAergic neurons, respectively) messenger RNA (mRNA). Study 2 used slice electrophysiology to measure intrinsic excitability and excitatory/inhibitory synaptic transmission in putative pyramidal neurons in the BLA. Physiological measures of injury severity were collected from all animals. Our results show that females exhibit increased apnea duration and reduced respiratory rate post-TBI relative to males. In male and female rats, TBI increased c-fos expression in BLA glutamatergic cells but not in BLA GABAergic cells, and TBI increased firing rate in BLA pyramidal neurons. Further, TBI increased spontaneous excitatory and inhibitory postsynaptic current (sEPSC and sIPSC) amplitude in BLA neurons of females relative to all other groups. TBI increased sEPSC frequency in BLA neurons of females relative to males but did not alter sIPSC frequency. In summary, lateral fluid percussion produced different physiological responses in male and female rats, as well as sex-specific alterations in BLA neuronal activation, excitability, and synaptic transmission 1 h after injury.

Assessment of the effect of the dual orexin receptor antagonist daridorexant on various indices of disease severity in patients with mild to moderate obstructive sleep apnea

BackgroundThe dual orexin receptor antagonist daridorexant did not impact nighttime respiratory function as assessed by the apnea/hypopnea index (AHI) and nocturnal oxygen saturation (SpO2) and improved sleep in patients with mild to moderate obstructive sleep apnea (OSA). These analyses were supplemented with further evaluations of various indices of OSA severity and sleep variables. MethodsIn this randomized, double-blind, placebo-controlled, two-period, crossover study, 50 mg daridorexant or placebo was administered every evening for 5 days to 28 patients with mild to moderate OSA. Treatment differences (daridorexant – placebo) were explored for indices of OSA severity including the number and duration of apneas and hypopneas, mean and lowest nocturnal SpO2, sleep duration during each hour of polysomnography recording, and the number and mean and longest duration of awakenings. ResultsAfter repeated-dose daridorexant, more respiratory events were observed compared to placebo, ie., treatment difference of 16.4 events (90% confidence interval: −0.4, 33.2) which is explained by a longer total sleep time. However, no treatment difference was detected for the longest duration of apneas and hypopneas (1.5 s [–8.3, 11.2] and 8.2 s [–6.6, 23.0], respectively), and lowest SpO2 (0.9% [–0.3, 2.1]). The number of awakenings was similar between daridorexant and placebo while daridorexant shortened the longest duration by 16.2 min (8.5, 23.8).Overall, results were similar after single and repeated dosing for both respiratory and sleep aspects. ConclusionThese results suggest safe use of daridorexant in patients with mild to moderate OSA. Clinical trial registrationClinicalTrials.gov NCT03765294. A study to investigate the effects of ACT-541468 on nighttime respiratory function in patients with mild to moderate obstructive sleep apnea. https://clinicaltrials.gov/ct2/show/NCT03765294.

Impact of Succinylcholine vs. Rocuronium on Apnea Duration for Rapid Sequence Induction: A Prospective Cohort Study.

ObjectiveThe present study aimed to evaluate the impact of 1.5 mg/kg succinylcholine or 1.2 mg/kg rocuronium, vs. 1.0 mg/kg succinylcholine on apnea duration in patients underwent rapid sequence induction (RSI).MethodsThis prospective cohort study was conducted in the Department of Anesthesiology in Shanghai General Hospital from July 2020 to November 2020. Apnea duration was defined as the time from apnea prompted by the PETCO2 waveform to the time the point of oxygen saturation declined to 90% (T90) and 95% (T95) after succinylcholine or rocuronium administration. The primary outcome included T90 and T95 changes in 1.5 mg/kg vs. 1.0 mg/kg succinylcholine groups and 1.5 mg/kg succinylcholine vs. 1.2 mg/kg rocuronium groups.ResultsA total of 265 participants were subjected for analysis. The succinylcholine (1.0 mg/kg) group had a significantly longer T90 (50.72, 95% confidence interval [CI, 7.60, 94.38], P = 0.015) and T95 (48.09, 95% CI [7.11, 89.07], P = 0.012) than the succinylcholine (1.5 mg/kg) group. In addition, significantly longer T90 (56.84, 95% CI [16.24, 97.44], P = 0.003) and T95 (50.57, 95% CI [12.58, 88.57], P = 0.003) were observed in the rocuronium (1.2 mg/kg) group than those in the succinylcholine (1.5 mg/kg) group. No severe side events were observed during the operation.ConclusionRocuronium and the lower dose of succinylcholine may be recommended to patients underwent RSI.

Exponential Relationship Between Maximal Apnea Duration and Exercise Intensity in Non-apnea Trained Individuals.

It is well known that the duration of apnea is longer in static than in dynamic conditions, but the impact of exercise intensity on the apnea duration needs to be investigated. The aim of this study was to determine the relationship between apnea duration and exercise intensity, and the associated metabolic parameters. Ten healthy active young non-apnea trained (NAT) men participated in this study. During the first visit, they carried out a maximum static apnea (SA) and a maximal progressive cycle exercise to evaluate the power output achieved at peak oxygen uptake (PVO2peak). During the second visit, they performed four randomized dynamic apneas (DAs) at 20, 30, 40, and 50% of PVO2peak (P20, P30, P40, and P50) preceded by 4 min of exercise without apnea. Duration of apnea, heart rate (HR), arterial oxygen saturation (SpO2), blood lactate concentration [La], rating of perceived exertion (RPE), and subjective feeling were recorded. Apnea duration was significantly higher during SA (68.1 ± 23.6 s) compared with DA. Apnea duration at P20 (35.6 ± 11.7 s) was higher compared with P30 (25.6 ± 6.3 s), P40 (19.2 ± 6.7 s), and P50 (16.9 ± 2.5 s). The relationship between apnea duration and exercise intensity followed an exponential function (y = 56.388e–0.025x). SA as DA performed at P20 and P30 induces a bradycardia. Apnea induces an SpO2 decrease which is higher during DA (−10%) compared with SA (−4.4%). The decreases of SPO2 recorded during DA do not differ despite the increase in exercise intensity. An increase of [La] was observed in P30 and P40 conditions. RPE and subjective feeling remained unchanged whatever the apnea conditions might be. These results suggest that the DA performed at 30% of VO2peak could be the best compromise between apnea duration and exercise intensity. Then, DA training at low intensity could be added to aerobic training since, despite the moderate hypoxia, it is sufficient to induce and increase [La] generally observed during high-intensity training.

Hypoxemia increases blood-brain barrier permeability during extreme apnea in humans

Voluntary asphyxia imposed by static apnea challenges blood-brain barrier (BBB) integrity in humans through transient extremes of hypertension, hypoxemia and hypercapnia. In the present study, ten ultra-elite breath-hold divers performed two maximal dry apneas preceded by normoxic normoventilation (NX: severe hypoxemia and hypercapnia) and hyperoxic hyperventilation (HX: absence of hypoxemia with exacerbating hypercapnia) with measurements obtained before and immediately after apnea. Transcerebral exchange of NVU proteins (ELISA, Single Molecule Array) were calculated as the product of global cerebral blood flow (gCBF, duplex ultrasound) and radial arterial to internal jugular venous concentration gradients. Apnea duration increased from 5 m 6 s in NX to 15 m 59 s in HX (P = <0.001) resulting in marked elevations in gCBF and venous S100B, glial fibrillary acidic protein, ubiquitin carboxy-terminal hydrolase-L1 and total tau (all P < 0.05 vs. baseline). This culminated in net cerebral output reflecting mildly increased BBB permeability and increased neuronal-gliovascular reactivity that was more pronounced in NX due to more severe systemic and intracranial hypertension (P < 0.05 vs. HX). These findings identify the hemodynamic stress to which the apneic brain is exposed, highlighting the critical contribution of hypoxemia and not just hypercapnia to BBB disruption.

Apnoeic oxygenation in morbid obesity: a randomised controlled trial comparing facemask and high-flow nasal oxygen delivery

BackgroundObesity is a risk factor for airway-related incidents during anaesthesia. High-flow nasal oxygen has been advocated to improve safety in high-risk groups, but its effectiveness in the obese population is uncertain. This study compared the effect of high-flow nasal oxygen and low-flow facemask oxygen delivery on duration of apnoea in morbidly obese patients. MethodsMorbidly obese patients undergoing bariatric surgery were randomly allocated to receive either high-flow nasal (70 L min−1) or facemask (15 L min−1) oxygen. After induction of anaesthesia, the patients were apnoeic for 18 min or until peripheral oxygen saturation decreased to 92%. ResultsEighty patients were studied (41 High-Flow Nasal Oxygen, 39 Facemask). The median apnoea time was 18 min in both the High-Flow Nasal Oxygen (IQR 18–18 min) and the Facemask (inter-quartile range [IQR], 4.1–18 min) groups. Five patients in the High-Flow Nasal Oxygen group and 14 patients in the Facemask group desaturated to 92% within 18 min. The risk of desaturation was significantly lower in the High-Flow Nasal Oxygen group (hazard ratio=0.27; 95% confidence interval [CI], 0.11–0.65; P=0.007). ConclusionsIn experienced hands, apnoeic oxygenation is possible in morbidly obese patients, and oxygen desaturation did not occur for 18 min in the majority of patients, whether oxygen delivery was high-flow nasal or low-flow facemask. High-flow nasal oxygen may reduce desaturation risk compared with facemask oxygen. Desaturation risk is a more clinically relevant outcome than duration of apnoea. Individual physiological factors are likely to be the primary determinant of risk rather than method of oxygen delivery. Clinical trial registrationNCT03428256.

Determining an optimum propofol infusion rate for induction of anaesthesia in healthy dogs: a randomized clinical trial

ObjectiveTo determine an optimum infusion rate of propofol that permitted rapid tracheal intubation while minimizing the duration of postinduction apnoea. Study designProspective, randomized, blinded clinical trial. AnimalsA total of 60 client-owned dogs presented for elective neutering and radiography. MethodsDogs were randomly allocated to one of five groups (groups A–E) to have propofol at an infusion rate of 0.5, 1, 2, 3, or 4 mg kg–1 minute–1, respectively, following intramuscular premedication with methadone 0.5 mg kg–1 and dexmedetomidine 5 μg kg–1. Propofol administration was stopped when adequate conditions for tracheal intubation were identified. Time to tracheal intubation and duration of apnoea were recorded. If oxygen haemoglobin saturation decreased to < 90%, manual ventilation was initiated. A one-way analysis of covariance was conducted to compare the effect of propofol infusion rate on duration of apnoea and intubation time whilst controlling for covariates, followed by post hoc tests. The significance level was set at p < 0.05. ResultsPropofol infusion rate had a significant effect on duration of apnoea (p = 0.004) and intubation time (p < 0.001) after controlling for bodyweight and sedation scores, respectively. The adjusted means (± standard error) of duration of apnoea were significantly shorter in groups A and B (49 ± 39 and 67 ± 37 seconds, respectively) than in groups C, D and E (207 ± 34, 192 ± 36 and 196 ± 34 seconds, respectively). Group B (115 ± 10 seconds) had a significantly shorter intubation time than group A (201 ± 10 seconds, p < 0.001). Conclusions and clinical relevanceAn infusion rate of 1.0 mg kg–1 minute–1 (group B) appears to offer the optimal compromise between speed of induction and duration of postinduction apnoea.

The Effects of Sleep Apnea and Sleep Duration on Bone Health: Findings from Densitometry and HR-pQCT in a Longitudinal Study

The Effects of Sleep Apnea and Sleep Duration on Bone Health: Findings from Densitometry and HR-pQCT in a Longitudinal Study

Association and Risk Factors for Obstructive Sleep Apnea and Cardiovascular Diseases: A Systematic Review

Obstructive sleep apnea (OSA) is a serious, potentially life-threatening condition. Epidemiologic studies show that sleep apnea increases cardiovascular diseases risk factors including hypertension, obesity, and diabetes mellitus. OSA is also responsible for serious illnesses such as congestive heart failure, stroke, arrhythmias, and bronchial asthma. The aim of this systematic review is to evaluate evidence for the association between OSA and cardiovascular disease morbidities and identify risk factors for the conditions. In a review of 34 studies conducted in 28 countries with a sample of 37,599 people, several comorbidities were identified in patients with severe OSA—these were: heart disease, stroke, kidney disease, asthma, COPD, acute heart failure, chronic heart failure, hyperlipidemia, thyroid disease, cerebral infarct or embolism, myocardial infarction, and psychological comorbidities including stress and depression. Important risk factors contributing to OSA included: age > 35 years; BMI ≥ 25 kg/m2; alcoholism; higher Epworth sleepiness scale (ESS); mean apnea duration; oxygen desaturation index (ODI); and nocturnal oxygen desaturation (NOD). Severe OSA (AHI ≥ 30) was significantly associated with excessive daytime sleepiness and oxygen desaturation index. The risk of OSA and associated disease morbidities can be reduced by controlling overweight/obesity, alcoholism, smoking, hypertension, diabetes mellitus, and hyperlipidemia.

Duration at high altitude influences the onset of arrhythmogenesis during apnea.

Autonomic control of the heart is balanced by sympathetic and parasympathetic inputs. Excitation of both sympathetic and parasympathetic systems occurs concurrently during certain perturbations such as hypoxia, which stimulate carotid chemoreflex to drive ventilation. It is well established that the chemoreflex becomes sensitized throughout hypoxic exposure; however, whether progressive sensitization alters cardiac autonomic activity remains unknown. We sought to determine the duration of hypoxic exposure at high altitude necessary to unmask cardiac arrhythmias during instances of voluntary apnea. Measurements of steady-state chemoreflex drive (SS-CD), continuous electrocardiogram (ECG) and SpO2 (pulse oximetry) were collected in 22 participants on 1day at low altitude (1045m) and over eight consecutive days at high-altitude (3800m). SS-CD was quantified as ventilation (L/min) over stimulus index (PETCO2/SpO2). Bradycardia during apnea was greater at high altitude compared to low altitude for all days (p < 0.001). Cardiac arrhythmias occurred during apnea each day but became most prevalent (> 50%) following Day 5 at high altitude. Changes in saturation during apnea and apnea duration did not affect the magnitude of bradycardia during apnea (ANCOVA; saturation, p = 0.15 and apnea duration, p = 0.988). Interestingly, the magnitude of bradycardia was correlated with the incidence of arrhythmia per day (r = 0.8; p = 0.004). Our findings suggest that persistent hypoxia gradually increases vagal tone with time, indicated by augmented bradycardia during apnea and progressively increased the incidence of arrhythmia at high altitude.

The frequency of obstructive sleep apnea in patients with primary Sjogren's syndrome.

IntroductionThere is a lack of information about the frequency of obstructive sleep apnea (OSA) in primary Sjogren’s syndrome (pSS). Using all-night polysomnography (PSG), this study aimed to investigate the frequency of OSA in pSS and the factors affecting the frequency of OSA in this condition. MethodsConsecutive patients with pSS who presented to the Collagen Tissue Diseases follow-up polyclinic of the Department of Chest Diseases between 1 April 2019 and 31 December, 2020, were included in the study. Demographic characteristics, chronic diseases, smoking history in pack-years, anthropometric data, Epworth Sleepiness Scale score, pulmonary function test parameters, current thorax computed tomography findings, and PSG data were recorded. The control group was created by the retrospective screening of patients admitted to the sleep polyclinic and who underwent PSG but did not have pSS.ResultsOSA was detected in 37 (84%) of 44 patients with pSS who underwent PSG. Of 37 patients with OSA, 25 (68%) had moderate or severe OSA. Snoring and witnessed apneas, REM%, snoring index, and maximum apnea and maximum hypopnea duration were statistically significantly lower in the pSS group compared with the control group (p < 0.001, p = 0.003, p = 0.025, p = 0.001, p = 0.028, and p = 0.035, respectively).ConclusionThe frequency of OSA in patients with pSS was 84%, with a decrease in REM%. Although a correlation between symptoms suggesting OSA and the presence of radiological lung involvement, spirometry, and DLCO values with OSA could not be demonstrated, physicians are recommended to be attentive for the presence of OSA in all patients with pSS and to investigate OSA using PSG.