The impact of childhood trauma on borderline personality organization in a community sample of Greek emerging adults

There is limited research on the role of childhood trauma in personality pathology according to Kernberg's psychodynamic model of internalized object relations. Because childhood trauma reflects the disruptions of these relations, it is expected to predict borderline personality organization, especially at the threshold of adulthood. Therefore, the main aim of this retrospective study was to examine the impact of childhood trauma on borderline personality organization in a community sample of emerging adults. Participants were 543 Greek individuals aged 18-29 (M = 21.45; 58.6 % females; 85.1 % university students). They completed the Greek versions of the Traumatic Antecedents Questionnaire (TAQ) and the Inventory of Personality Organization (IPO), which were tested for their factorial structure, reliability, and measurement invariance across gender, as few empirical data exist on the psychometric properties of these measures. Confirmatory factor analyses showed that the TAQ consisted of four factors, namely positive experiences, abuse, traumatic life events, and family chaos. The five-factor theoretical structure of the IPO, namely primitive defenses, identity diffusion, reality testing, aggression, and moral values, was confirmed. Low to moderate links between childhood trauma and borderline personality organization were found, with stronger links emerging for abuse and family chaos. Structural equation modeling showed that the various forms of childhood trauma across the age periods studied (i.e., 0-6, 7-12, 13-18) significantly and differentially predicted the dimensions of borderline personality organization. The finding that stronger links emerged when trauma occurred in older ages may be attributed to the retrospective method of the study. Gender differences were also found; for example, personality pathology was more likely in men when abuse and traumatic life events occurred in younger ages and abuse was a more important risk factor for personality pathology in women. This study highlights the impact of childhood adversity on personality pathology in emerging adulthood, provides empirical support for Kernberg's psychodynamic model, and has useful implications for trauma-informed early screening, prevention, and intervention regarding personality pathology in young people. Limitations of this study and suggestions for future research are outlined.

Contribution of obstructive sleep apnea to disrupted sleep in a large clinical cohort of patients with suspected obstructive sleep apnea

STUDY OBJECTIVES

The response of sleep depth to CPAP in patients with OSA is unpredictable. The odds-ratio-product (ORP) is a continuous index of sleep depth and wake propensity that distinguishes different sleep depths within sleep stages, and different levels of vigilance during stage wake. When expressed as fractions of time spent in different ORP deciles, nine distinctive patterns are found. Only three of these are associated with OSA. We sought to determine whether sleep depth improves on CPAP exclusively in patients with these three ORP patterns.

METHODS

ORP was measured during the diagnostic and therapeutic components of 576 split-night polysomnographic (PSG) studies. ORP architecture in the diagnostic section was classified into one of the nine possible ORP patterns and the changes in sleep architecture were determined on CPAP for each of these patterns. ORP architecture was similarly determined in the first half of 760 full-night diagnostic PSG studies and the changes in the second half were measured to control for differences in sleep architecture between the early and late portions of sleep time in the absence of CPAP.

RESULTS

Frequency of the three ORP patterns increased progressively with the apnea-hypopnea index. Sleep depth improved significantly on CPAP only in the three ORP patterns associated with OSA. Changes in CPAP in the other six patterns, or in full diagnostic PSG studies, were insignificant or paradoxical.

CONCLUSIONS

ORP architecture types can identify patients in whom OSA adversely affects sleep and whose sleep is expected to improve on CPAP therapy.

Transdiagnostic cognitive behavioral therapy for nightmares and parasomnias

STUDY OBJECTIVES

This pilot study determined whether transdiagnostic cognitive behavioral therapy for parasomnias (CBTp) reduces parasomnia and activity levels during sleep in a sample of adult sleep clinic outpatients. A secondary objective was to assess whether treatment produces improvements in daytime fatigue/sleepiness, perceived cognition, mood, and depression/anxiety/stress, as well as functional impairment in work and leisure activities.

METHODS

This was a randomized controlled trial with CBTp and self-monitoring control conditions. Participants were 19 adults with a DSM 5 parasomnia disorder who received individual CBTp virtually from their homes. CBTp consisted of psychoeducation, sleep hygiene and safety instructions, relaxation training, parasomnia techniques, and relapse prevention in a 6-week manualized, structured program.

RESULTS

Using a repeated measures analysis of variance model, and relative to a self-monitoring control condition, results showed that CBTp produced statistically significant improvements in parasomnia frequency, severity, nocturnal activity, and sleep efficiency. There was a trend toward reduced sleep-onset latency and improved work and social adjustment. Of treated participants, 100% rated themselves as improved at study conclusion.

CONCLUSIONS

Implications of these findings are that cognitive behavioral interventions for parasomnias are effective in lessening parasomnias. More investigation into this type of treatment is warranted.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Impact of Cognitive Behavioral Therapy on Parasomnias; URL: https://clinicaltrials.gov/ct2/show/NCT04633668; Identifier: NCT04633668.

CITATION

Vincent N, Dirkse D, Giannouli E, McQuarrie A. Transdiagnostic cognitive behavioral therapy for nightmares and parasomnias. J Clin Sleep Med. 2023;19(3):499-509.

Patient-reported needs predict perceived psychosocial disability and quality of life beyond symptom severity in schizophrenia

PURPOSE

We examined whether patient-rated or clinician-rated needs are more strongly associated with perceived psychosocial disability (PPD) and subjective quality of life (SQOL) of schizophrenia patients, beyond symptom severity.

METHODS

Hierarchical regression analyses were computed to test patient and clinician-rated unmet and met needs (estimated by eighty-two patient-clinician pairs) as predictors of PPD and SQOL above and beyond demographics and psychopathology. Needs, symptomatology, PPD and SQOL were estimated using Camberwell Assessment of Need (CAN), PANSS, WHODAS 2.0 and WHOQOL-BREF respectively.

RESULTS

Needs were significantly associated with all WHODAS 2.0 and WHOQOL-BREF domains above and beyond demographics and PANSS variables. Clinician-rated needs were better predictors of only one WHODAS 2.0 domain, while patient-rated needs were better predictors of all other WHODAS 2.0 and WHOQOL-BREF domains. Patient-rated unmet needs were more strongly than met needs associated with the most WHODAS 2.0 and WHOQOL-BREF subscores.

CONCLUSION

This study offers the first evidence that patient-rated needs, especially unmet needs, are strongly associated, above and beyond symptomatology, with global and domain-specific PPD of schizophrenia patients. Accordingly, strong relations of patient-rated needs with SQOL emerged. Identifying and addressing patient-reported needs could facilitate PPD and SQOL improvement more effectively than interventions confined solely to symptom remission.IMPLICATIONS FOR REHABILITATIONSchizophrenia is associated with poor rehabilitation and recovery outcomes, i.e., perceived psychosocial disability (PPD) and subjective quality of life (SQOL).Assessment of patients' needs constitutes the basis of determining treatment goals and planning tailor-made interventions to achieve crucial rehabilitative outcomes.Higher levels of patient-reported unmet needs are associated with poorer SQOL and higher global and domain-specific PPD of schizophrenia patients, above and beyond symptom severity.Addressing patient-reported needs through personalized interventions can facilitate more effectively PPD and SQOL improvement, than treatment confined to symptomatic alleviation.

Fear of COVID-19 Impact on Professional Quality of Life among Mental Health Workers

Several studies have examined the impact of the COVID-19 pandemic on healthcare workers' mental health, but only a few have investigated its detrimental effect on the mental well-being of mental health workers (MHWs).

BACKGROUND

The current study aimed to explore the effect of the fear of COVID-19 (FCV-19) on professional quality of life dimensions, namely compassion satisfaction (CS), burnout (BO), and secondary traumatic stress (STS) in MHWs above and beyond sociodemographic and professional factors.

METHODS

Hierarchical linear regression models were employed to examine the relationship of extreme FCV-19 with CS, BO, and STS in MHWs (n = 224), after considering sociodemographic variables as potential confounding factors. Extreme FCV-19 was operationalized as a binary variable with a cut-off score of ≥16.5 considered as extreme fear.

RESULTS

We found that extreme FCV-19 in MHWs is linked with increased compassion fatigue (BO and STS), and this relationship is exacerbated by younger age in regard to BO and by female gender concerning STS. CS remains unaffected by severe FCV-19, and it is higher in older participants.

CONCLUSION

Organizational support is required to protect MHWs' mental well-being and ensure the quality of care they provide during prolonged crises, such as the COVID-19 pandemic. Measures that intensify a sense of safety, protection, and control against COVID-19 infections in mental health services should be included in the recommendations that may reduce BO and STS among MHWs.

Acoustic characterization of upper airway variations from wakefulness to sleep with respect to obstructive sleep apnea

The upper airway (UA) is in general thicker and narrower in obstructive sleep apnea (OSA) population than in normal. Additionally, the UA changes during sleep are much more in the OSA population. The UA changes can alter the tracheal breathing sound (TBS) characteristics. Therefore, we hypothesize the TBS changes from wakefulness to sleep are significantly correlated to the OSA severity; thus, they may represent the physiological characteristics of the UA. To investigate our hypothesis, we recorded TBS of 18 mild-OSA (AHI < 15) and 22 moderate/severe-OSA (AHI > 15) during daytime (wakefulness) and then during sleep. The power spectral density (PSD) of the TBS was calculated and compared within the two OSA groups and between wakefulness and sleep. The average PSD of the mild-OSA group in the low-frequency range (< 280 Hz) was found to be decreased significantly from wakefulness to sleep (p-value < 10^-4). On the other hand, the average PSD of the moderate/severe-OSA group in the high-frequency range (> 900 Hz) increased marginally significantly from wakefulness to sleep (p-value < 9 × 10^-3). Our findings show that the changes in spectral characteristics of TBS from wakefulness to sleep correlate with the severity of OSA and can represent physiological variations of UA. Therefore, TBS analysis has the potentials to assist with diagnosis and clinical management decisions in OSA patients based on their OSA severity stratification; thus, obviating the need for more expensive and time-consuming sleep studies. Graphical abstract Tracheal breathing sound (TBS) changes from wakefulness to sleep and their correlation with Obstructive sleep apnea (OSA) were investigated in individuals with different levels of OSA severity. We also assessed the classification power of the spectral characteristics of these TBS for screening purposes. Consequently, we analyzed and compared spectral characteristics of TBS recorded during wakefulness (a combination of mouth and nasal TBS) to those during sleep for mild and moderate/severe OSA groups.

Metacognitive factors in a sample of Greek alcohol dependent patients

Introduction

The harmful use of alcohol causes a large disease, social and economic burden in societies. Metacognition is a complex concept referring to the cognitive control and regulation of many types of cognitive processes.

Objectives

Metacognitions are considered to be an important factor in the development and continuance of psychological disorders.

Aims

The purpose of this study is to examine the probable relations between alcohol abuse and Metacognitions with the Metacognitions Questionaire – 30 (MCQ-30).

Method

Twenty-three men and 16 women, aged between 22 and 64 years, inpatients in Eginition Hospital, due to alcohol dependence, completed the Greek-Version of the MCQ-30.

Results

The mean total scores of alcoholics were higher than the ones of the healthy subjects. Namely, the group of the alcohol abused patients presented a higher score in comparison with the normal group in three of the five metacognitive dimensions. Additionally, alcoholic men outscored alcoholic women in two of the five factors. Specifically, alcoholic men appeared to be less confident about their memory and attention than alcoholic women. Furthermore, alcoholic men, compared to alcoholic women claimed in a significant greater level that worrying helped them to function.

Conclusions

The above findings suggest that metacognitions could play a role in the orientation and maintenance of alcoholic abuse behavior. Moreover, these results may pose the question of whether these metacognitive beliefs could be seen as an indicator of differentiating alcoholic men from women. Overall, further research could provide additional information concerning the relation between Metacognitions and alcoholic dependence.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Mechanism of excessive wake time when associated with obstructive sleep apnea or periodic limb movements

STUDY OBJECTIVES

It is uncertain whether obstructive apnea (OSA) or periodic limb movements (PLMs) contribute to excessive wake time (EWT) when EWT and these disorders coexist. We hypothesized that such EWT is an independent disorder related to central regulation of sleep depth. Accordingly, we compared sleep depth in patients with EWT and OSA/PLMs (EWT+P) with patients with EWT and no OSA/PLMs (EWT-NP) and patients with a normal wake time.

METHODS

A total of 267 participants were divided into five groups: (1) EWT+P: n = 100 (wake time > 20% total recording time; TRT) with OSA (apnea-hypopnea index 5-110 events/h) and/or PLMs (PLM index 10-151 events/h); (2) EWT-NP: n = 49 (wake time > 20%TRT), no associated pathology; (3) normal wake time (NWT)+P: n = 54 (wake time < 20%TRT, with OSA/PLMs); (4) NWT-NP: n = 26; (5) Healthy participants: n = 38 (no sleep complaints, NWT and no OSA/PLMs). Sleep depth was evaluated by the odds ratio product (ORP; 0 = deep sleep, 2.5 = fully alert). We also measured ORP in the 9 seconds immediately following arousals (ORP-9) to distinguish between peripheral and central mechanisms of light sleep.

RESULTS

ORP during sleep was higher (lighter sleep) in both EWT groups than in the three NWT groups (P < 1E-11) with no difference between those with and those without OSA/PLMs. ORP-9 was also significantly higher in the EWT groups than in the NWT groups (P < 1E-19), also with no difference between those with and without OSA/PLMs, indicating that the lighter sleep was of central origin. There were highly significant correlations between wake time and ORP-9 across all groups (P < 1E-35).

CONCLUSIONS

EWT associated with OSA/PLMs is independent of OSA/PLMs and related to abnormal central regulation of sleep depth.

Performance of a New Portable Wireless Sleep Monitor

STUDY OBJECTIVES

To determine if signals generated by a new sleep monitor (Prodigy) are comparable to signals generated during in-laboratory polysomnography (PSG).

METHODS

Fifty-nine patients with various sleep disorders (25 with moderate/severe sleep apnea) were studied. Full PSG was performed using standard acquisition systems. Prodigy was attached to the forehead with four disposable snap electrodes. Four additional electrodes were attached to monitor eye movements and muscle activity, and to serve as reference (mastoid). One frontal EEG signal was outputted in real time from the monitor and stored in the PSG record along with the other PSG signals. PSG was scored for sleep variables manually, and monitor records were scored by a validated automatic system (MSS) (MSS-Prodigy). MSS-Prodigy was briefly edited following suggestions of an Editing Helper feature of MSS.

RESULTS

Technical failures resulted in one study being unusable and another with data for only 3 hours. Prodigy EEG signal stored in the PSG record was visually indistinguishable from the PSG-derived EEG signals. Important differences between manual scores and unedited MSS-Prodigy were seen in a few patients in some sleep variables (notably onset latencies and REM time). Editing Helper issued 2.1 ± 0.8 suggestions/file. Only these suggestions were pursued during editing. Intraclass correlation coefficients for manual vs. edited MSS-Prodigy were > 0.83 for all sleep variables except for stages N1 and N3 (0.57 and 0.58).

CONCLUSIONS

When scored with MSS, and with only very minor editing, the monitor's results show excellent agreement with manual scoring of polysomnography data, even in patients with severe sleep disorders.

Accuracy of Automatic Polysomnography Scoring Using Frontal Electrodes

STUDY OBJECTIVES

The economic cost of performing sleep monitoring at home is a major deterrent to adding sleep data during home studies for investigation of sleep apnea and to investigating non-respiratory sleep complaints. Michele Sleep Scoring System (MSS) is a validated automatic system that utilizes central electroencephalography (EEG) derivations and requires minimal editing. We wished to determine if MSS' accuracy is maintained if frontal derivations are used instead. If confirmed, home sleep monitoring would not require home setup or lengthy manual scoring by technologists.

METHODS

One hundred two polysomnograms (PSGs) previously recorded from patients with assorted sleep disorders were scored using MSS once with central and once with frontal derivations. Total sleep time, sleep/stage R sleep onset latencies, awake time, time in different sleep stages, arousal/awakening index and apnea-hypopnea index were compared. In addition, odds ratio product (ORP), a continuous index of sleep depth/quality (Sleep 2015;38:641-54), was generated for every 30-sec epoch in each PSG and epoch-by-epoch comparison of ORP was performed.

RESULTS

Intraclass correlation coefficients (ICCs) ranged from 0.89 to 1.0 for the various sleep variables (0.96 ± 0.03). For epoch-by-epoch comparisons of ORP, ICC was > 0.85 in 96 PSGs. Lower values in the other six PSGs were related to signal artifacts in either derivation. ICC for whole-record average ORP was 0.98.

CONCLUSIONS

MSS is as accurate with frontal as with central EEG derivations. The use of frontal electrodes along with MSS should make it possible to obtain high-quality sleep data without requiring home setup or lengthy scoring time by expert technologists.

The Concept of Time Perspective Within a Psychiatric Context

Introduction

According to time perspective (TP), theory behaviour is influenced by the individual's perception of his/her past, present and future. Boyd and Zimbardo postulate that a healthy balance between orientation to the past, present and future exists.

Objectives

Investigation of TP in the context of psychopathology.

Aims

To investigate and compare TP in Obsessive Compulsive (OCD) and Borderline Personality Disorder (BPD).

Method

Twenty-eight OCD and 28 BPD patients (36% of men), matched for age and education, completed the Greek version of the Zimbardo Time Perspective Inventory (ZTPI); a 56-item self-administered questionnaire measuring individuals’ orientations to the past, present, and future. ZTPI consists of five factors: Past Negative (PN), Past Positive (PP), Present Hedonistic (PH), Present Fatalistic (PF) and Future (F).

Results

BPD patients scored significantly higher in PH and PF and significantly lower in PP factors than OCD patients. No significant gender differences emerged for either group. In the BPD group, age correlated significantly negatively with PH, while education correlated positively with F.

Conclusion

The study's findings suggest that BPD patients have a hedonistic orientation towards time and life and a helpless/hopeless attitude towards the future to a significantly greater degree than OCD patients, whereas OCD patients seem to have a more positive and nostalgic attitude towards the past than BPD patients. Further research would provide additional information concerning the role of TP in OCD and BPD patients.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Enhancements to the multiple sleep latency test

INTRODUCTION

The utility of multiple sleep latency tests (MSLTs) is limited to determining sleep onset latency (SOL) and rapid eye movement sleep latency. The odds ratio product (ORP) is a continuous index of sleep depth with values of 0, 1.0, and 2.5 reflecting very deep sleep, light sleep, and full wakefulness, respectively. We determined the time course of sleep depth during MSLT naps expecting that this would enhance the test's clinical utility.

METHODS

Thirty MSLTs (150 naps) were performed for excessive somnolence. Patients indicated whether they slept (yes/no) after each nap. SOL was scored by two experienced technologists. Time course of ORP was determined with a commercial system. We determined ORP at SOL (ORPSOL), times ORP decreased <2.0, <1.5, <1.0 and <0.5 during the entire nap duration, and the integral of decrease in ORP over nap duration (ΔORPINT).

RESULTS

SOL occurred almost invariably when ORP was between 1.0 and 2.0. Of 47 naps (21 patients) with SOL <5 minutes, ORP decreased <1.0 (light sleep) in <5 minutes in only 13 naps (nine patients) and <0.5 (deep sleep) in only two naps in one patient. The relation between ORPINT and frequency of sleep perception was well defined, allowing determination of a threshold for sleep perception. This threshold ranged widely (5-50 ΔORP*epoch).

CONCLUSION

As currently identified, SOL reflects transition into a highly unstable state between wakefulness and sleep. Reporting the times of attaining different sleep depths may help better identify patients at high risk of vigilance loss. Furthermore, an ORPSOL outside the range 1.0-2.0 can help identify scoring errors.

Measuring the needs of mental health patients in Greece: reliability and validity of the Greek version of the Camberwell assessment of need

BACKGROUND

Evaluation of mental health services based on patients' needs assessments has never taken place in Greece, although it is a crucial factor for the efficient use of their limited resources.

AIM

To examine the inter-rater and test-retest reliability and the concurrent/convergent validity of the Greek research version of the Camberwell Assessment of Need-Research (CAN-R).

METHOD

A total of 53 schizophrenic patient-staff pairs were interviewed twice to test the inter-rater and test-retest reliability of the Greek version of the CAN-R. The World Health Organization Quality of Life-Brief Form (WHOQOL-BREF) and World Health Organization Disability Assessment Schedule-2.0 (WHODAS-2.0) were administered to the patients to examine concurrent validity.

RESULTS

The inter-rater and test-retest reliability of patient and staff interviews for the 22 individual items and the eight summary scores of the instrument's four sections were good to excellent. Significant correlations emerged between CAN scores and the WHOQOL-BREF and WHODAS-2.0 domains for both patient and staff ratings, indicating good concurrent validity.

CONCLUSION

Our results suggest that the Greek version of the CAN-R is a reliable instrument for assessing mental health patients' needs. Moreover, it is the first CAN-R validity study with satisfactory results using WHOQOL-BREF and WHODAS-2.0 as criterion variables.

Assessment of obstructive sleep apnea and its severity during wakefulness

In this article, a novel technique for assessment of obstructive sleep apnea (OSA) during wakefulness is proposed; the technique is based on tracheal breath sound analysis of normal breathing in upright sitting and supine body positions. We recorded tracheal breath sounds of 17 non-apneic individuals and 35 people with various degrees of severity of OSA in supine and upright sitting positions during both nose and mouth breathing at medium flow rate. We calculated the power spectrum, Kurtosis, and Katz fractal dimensions of the recorded signals and used the one-way analysis of variance to select the features, which were statistically significant between the groups. Then, the maximum relevancy minimum redundancy method was used to reduce the number of characteristic features to two. Using the best two selected features, we classified the participant into severe OSA and non-OSA groups as well as non-OSA or mild vs. moderate and severe OSA groups; the results showed more than 91 and 83% accuracy; 85 and 81% specificity; 92 and 95% sensitivity, for the two types of classification, respectively. The results are encouraging for identifying people with OSA and also prediction of OSA severity. Once verified on a larger population, the proposed method offers a simple and non-invasive screening tool for prediction of OSA during wakefulness.

Security rules and banned items in psychiatric acute admission wards in Athens, Greece

Mental health nurses play a key role in maintaining the safety of patients, themselves, and others during hospitalization. The aim of the research was to evaluate the safety measures that are taken by mental health nurses to identify the security policies that exist in acute mental health wards. The Ward Safety and Security Rules Survey was used as a method of data collection. Descriptive analysis and content analysis were carried out in order to identify nurses' practices. The total sample consisted of 172 mental health nurses and nurses' assistants who worked in 14 acute inpatient psychiatric wards in three psychiatric hospitals in the greater area of Athens, Greece. The results show a minimum number of security features existing in the wards. Only one of the 14 wards had an intercom system. In only nine wards, there was a panic alarm in the office, and in eight, an emergency response telephone extension. A wide range of practices were noted concerning banned items and patient searches upon admission and return from leave. The results indicate the significant lack of protocols and specific safety rules to guide nurses' actions across psychiatric acute admission wards in Athens.

[Security rules in acute inpatient wards in psychiatric hospitals in the greater area of Athens]

This research concerns the recording of safety measures in acute mental health wards of psychiatric hospitals in the greater area of Athens. The practices of control and testing on patients performed by nurses are also reported. The total sample consists of 14 acute inpatient psychiatric wards. The results indicated that important differences were noticed in the controls and prohibitions. Moreover, the main characteristic was the lack of protocols and measures of safety, a situation that burdened nursing practice. The lack of rules and strategies that would promote the safety of patient, professionals and therapeutic milieu, were brought into light by nurses' quotes.

Postpolio Syndrome and Anesthesia

The development of polio vaccines 50 yr ago essentially halted childhood polio epidemics in the industrialized world. During the past quarter century, a constellation of delayed neuromuscular symptoms, called postpolio syndrome, became recognized among the aging polio survivors. The prevalence of postpolio syndrome in the U.S. population is estimated to be in the hundreds of thousands. The most common symptoms are fatigue, pain, and new onset weakness thought to be related to delayed deterioration of motor neuron function. When a patient with postpolio syndrome presents for surgery, special precautions are warranted, because these patients may have respiratory impairment, sleep apnea, swallowing difficulties, and cold intolerance. This article first reviews clinical features and some pathoetiologic theories of postpolio syndrome and then focuses on anesthetic considerations including the use of common anesthetics, neuromuscular blockade, regional anesthesia, and general anesthetic management strategies.

Response of ventilator-dependent patients to different levels of pressure support and proportional assist

The ventilator's response to the patient's effort is quite different in proportional assist ventilation (PAV) and pressure support ventilation (PSV). We wished to determine whether this results in different ventilatory and breathing pattern responses to alterations in level of support and, if so, whether there are any gas exchange consequences. Fourteen patients were studied. Average elastance (E) was 22.8 (range, 14 -36) cm H2O/L and average resistance (R) was 15. 7 (range, 9-21) cm H2O/L/s. The highest PSV support (PSVmax) was that associated with a tidal volume (VT) of 10 ml/kg (20.4 +/- 3.2 cm H2O), and the highest level of PAV assist (PAVmax) was 78 +/- 7% of E and 76 +/- 7% of R. Level of assist was decreased in steps to the lowest tolerable level (PSVmin, PAVmin). Minute ventilation, VT, ventilator rate (RRvent), and arterial gas tensions were measured at each level. We also determined the patient's respiratory rate (RRpat) by adding the number of ineffective efforts (DeltaRR) to RRvent. There was no difference between PSVmin and PAVmin in any of the variables. At PSVmax, VT was significantly higher (0.90 +/- 0.30 versus 0.51 +/- 0.16 L) and RRvent was significantly lower (13.2 +/- 3.9 versus 27.6 +/- 10.5 min-1) than at PAVmax. The difference in RRvent was largely related to a progressive increase in ineffective efforts on PSV as level increased (DeltaRR 12.1 +/- 10.1 vs 1.4 +/- 2.1 with PAVmax); there was no significant difference in RRpat. The differences in breathing pattern had no consequence on arterial blood gas tensions. We conclude that substantial differences in breathing pattern may occur between PSV and PAV and that these are largely artifactual and related to different patient-ventilator interactions.

Control of breathing during sleep assessed by proportional assist ventilation

We used proportional assist ventilation (PAV) to evaluate the sources of respiratory drive during sleep. PAV increases the slope of the relation between tidal volume (VT) and respiratory muscle pressure output (Pmus). We reasoned that if respiratory drive is dominated by chemical factors, progressive increase of PAV gain should result in only a small increase in VT because Pmus would be downregulated substantially as a result of small decreases in PCO2. In the presence of substantial nonchemical sources of drive [believed to be the case in rapid-eye-movement (REM) sleep] PAV should result in a substantial increase in minute ventilation and reduction in PCO2 as the output related to the chemically insensitive drive source is amplified severalfold. Twelve normal subjects underwent polysomnography while connected to a PAV ventilator. Continuous positive air pressure (5.2 +/- 2.0 cmH2O) was administered to stabilize the upper airway. PAV was increased in 2-min steps from 0 to 20, 40, 60, 80, and 90% of the subject's elastance and resistance. VT, respiratory rate, minute ventilation, and end-tidal CO2 pressure were measured at the different levels, and Pmus was calculated. Observations were obtained in stage 2 sleep (n = 12), slow-wave sleep (n = 11), and REM sleep (n = 7). In all cases, Pmus was substantially downregulated with increase in assist so that the increase in VT, although significant (P < 0.05), was small 0.08 liter at the highest assist). There was no difference in response between REM and non-REM sleep. We conclude that respiratory drive during sleep is dominated by chemical control and that there is no fundamental difference between REM and non-REM sleep in this regard. REM sleep appears to simply add bidirectional noise to what is basically a chemically controlled respiratory output.

Effects of extrinsic positive end-expiratory pressure on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

OBJECTIVE

To examine the circulatory and respiratory effects of extrinsic positive end-expiratory pressure (PEEPe) in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation during controlled mechanical ventilation.

DESIGN

Different levels of PEEPe were applied randomly in mechanically ventilated patients with COPD and dynamic hyperinflation.

SETTING

Respiratory Intensive Care Unit of a University Hospital.

PATIENTS

9 patients with acute respiratory failure and dynamic hyperinflation due to acute exacerbation of COPD.

INTERVENTIONS

PEEPe 35%, 58% and 86% of intrinsic PEEP (PEEPi) were applied.

MEASUREMENTS AND RESULTS

Using flow-directed pulmonary artery catheters hemodynamic measurements were obtained, while simultaneously lung volumes, airflows and airway pressures were recorded. In order to estimate alveolar pressures (Palv), rapid airway occlusions during passive expiration were also performed. At no level of PEEPe were significant changes in cardiac output, gas exchange variables, dead space, airways inflation resistances and respiratory system static end-inspiratory compliance observed. At high level of PEEPe central venous, mean pulmonary arterial and pulmonary capillary wedge pressures were increased significantly. All but one patient were flow-limited during passive expiration. PEEPe 86% of PEEPi caused a significant increase in end-expiratory lung volume and total PEEP. Iso-volume pressure-flow curves showed volume-dependence expiratory flow limitation in 2 patients, while in 8 patients volume-dependence of critical driving pressure (Palv-mouth pressure) that decreased flows was also observed.

CONCLUSIONS

The effects of PEEPe on iso-volume flow and hence on lung mechanics and hemodynamics, depend on many factors, such as airways resistances, lung volumes and airway characteristics, making the patient response to PEEPe unpredictable.

Respiratory short-term poststimulus potentiation (after-discharge) in patients with obstructive sleep apnea

In conscious normal humans after a brief hypoxic ventilatory stimulus, ventilation slowly decays to baseline and does not undershoot though the subjects are hyperoxic and hypocapnic. This phenomenon is attributed to short-term poststimulus potentiation (STP), which may be an important factor promoting ventilatory stability by preventing periodic breathing. It has been proposed that obstructive sleep apnea (OSA) is a variant of periodic breathing, with obstruction occurring when ventilatory drive is low. If this were the case, patients with OSA might have reduced STP. To test this, seven normal adults and 12 patients with OSA (mean apnea index, 52.4 +/- 6.9 SE events/h) were studied. Ventilation (VI) was measured in awake seated subjects during 30 to 45 s of exposure to hypoxia (end-tidal O2: 50 mm Hg) followed by hyperoxia. A total of 57 hypoxic-hyperoxic runs were analyzed (36 in the patients and 21 in the normal subjects). During hypoxia VI increased and end-tidal CO2 decreased by similar amounts in both groups. In normal subjects after hypoxia there was a gradual decay in VI to prehypoxic levels without an undershoot. In patients, there was on average a ventilatory undershoot at 35 s of hyperoxia, with a mean VI of 83% of baseline. The undershoot was due mainly to a decrease in tidal volume, which was significantly lower than that of the normal subjects for several seconds. These changes were particularly prominent in seven patients who were not different from the others in terms of baseline characteristics, hypoxic responses, and OSA severity.(ABSTRACT TRUNCATED AT 250 WORDS)