Relationship between postpartum mood disorder and birth experience: a prospective observational study.

BACKGROUND: This study aims to investigate the relationship between the birth experience and the risk of developing postpartum depression or post-traumatic stress disorder. METHODS: In this prospective, longitudinal, observational study, women were assessed at different time points for depression and post-traumatic stress disorder. The risk of depression or post-traumatic stress disorder based on patient characteristics and specific birth events was assessed within three months postpartum. RESULTS: We enrolled 600 women; 426 were eligible for postpartum assessment. At six weeks and three months postpartum, 15.9% and 12.7% screened positive for depression respectively. Positive post-traumatic stress disorder screenings at six weeks and three months postpartum were 6.2% and 5.1% respectively. Twenty-seven women (8.3%) with a negative screening at six weeks converted to a positive depression or post-traumatic stress disorder screening at three months. A pre-existing history of anxiety or depression was associated with an increased risk of developing depression (aOR 2.12, 95% CI 1.30 to 3.47) and post-traumatic stress (aOR 3.15, 95% CI 1.42 to 7.02) within three months postpartum. The risk of developing post-traumatic stress disorder within three months postpartum was also increased among patients experiencing their first delivery (aOR 2.55, 95% CI 1.10 to 5.88) or operative management of postpartum hemorrhage (aOR 4.44, 95% CI 1.16 to 17.02). CONCLUSION: Depression and post-traumatic stress symptoms either persisted or had new onset at three months postpartum. Mental health screening and postpartum follow-up after six weeks should be considered in high-risk patients who have a history of psychopathology, nulliparity, or undergo operative management of postpartum hemorrhage.

Duration of EEG suppression does not predict recovery time or degree of cognitive impairment after general anaesthesia in human volunteers.

BACKGROUND: Burst suppression occurs in the EEG during coma and under general anaesthesia. It has been assumed that burst suppression represents a deeper state of anaesthesia from which it is more difficult to recover. This has not been directly demonstrated, however. Here, we test this hypothesis directly by assessing relationships between EEG suppression in human volunteers and recovery of consciousness. METHODS: We recorded the EEG of 27 healthy humans (nine women/18 men) anaesthetised with isoflurane 1.3 minimum alveolar concentration (MAC) for 3 h. Periods of EEG suppression and non-suppression were separated using principal component analysis of the spectrogram. After emergence, participants completed the digit symbol substitution test and the psychomotor vigilance test. RESULTS: Volunteers demonstrated marked variability in multiple features of the suppressed EEG. In order to test the hypothesis that, for an individual subject, inclusion of features of suppression would improve accuracy of a model built to predict time of emergence, two types of models were constructed: one with a suppression-related feature included and one without. Contrary to our hypothesis, Akaike information criterion demonstrated that the addition of a suppression-related feature did not improve the ability of the model to predict time to emergence. Furthermore, the amounts of EEG suppression and decrements in cognitive task performance relative to pre-anaesthesia baseline were not significantly correlated. CONCLUSIONS: These findings suggest that, in contrast to current assumptions, EEG suppression in and of itself is not an important determinant of recovery time or the degree of cognitive impairment upon emergence from anaesthesia in healthy adults.

Intraoperative ketamine for prevention of depressive symptoms after major surgery in older adults: an international, multicentre, double-blind, randomised clinical trial.

BACKGROUND: Ketamine is a general anaesthetic with anti-depressant effects at subanaesthetic doses. We hypothesised that intraoperative administration of ketamine would prevent or mitigate postoperative depressive symptoms in surgical patients. METHODS: We conducted an international, randomised clinical trial testing the effects of intraoperative administration of ketamine [0.5 mg kg-1 (Lo-K) or 1.0 mg kg-1 (Hi-K)] vs control [saline placebo (P)] in patients ≥60 yr old undergoing major surgery with general anaesthesia. We administered the Patient Health Questionnaire-8 before the operation, on postoperative day (POD) 3 (primary outcome), and on POD30 to assess depressive symptoms, a secondary outcome of the original trial. RESULTS: There was no significant difference on POD3 in the proportion of patients with symptoms suggestive of depression between the placebo [23/156 (14.7%)] and combined ketamine (Lo-K plus Hi-K) [61/349 (17.5%)] groups [difference = -2.7%; 95% confidence interval (CI), 5.0% to -9.4%; P=0.446]. Of the total cohort, 9.6% (64/670; 95% CI, 7.6-12.0%) had symptoms suggestive of depression before operation, which increased to 16.6% (84/505; 95% CI, 13.6-20.1%) on POD3, and decreased to 11.9% (47/395; 95% CI, 9.1-15.5%) on POD30. Of the patients with depressive symptoms on POD3 and POD30, 51% and 49%, respectively, had no prior history of depression or depressive symptoms. CONCLUSIONS: Major surgery is associated with new-onset symptoms suggestive of depression in patients ≥60 yr old. Intraoperative administration of subanaesthetic ketamine does not appear to prevent or improve depressive symptoms. CLINICAL TRIALS REGISTRATION: NCT01690988.

Subanaesthetic ketamine and altered states of consciousness in humans.

BACKGROUND: Despite its designation as a 'dissociative anaesthetic,' the dissociative and psychoactive effects of ketamine remain incompletely understood. The goal of this study was to characterise the subjective experiences and accompanying EEG changes with subanaesthetic doses of ketamine. METHODS: High-density EEG was recorded in 15 human volunteers before, during, and after subanaesthetic ketamine infusion (0.5 mg kg-1 over 40 min), with self-reported measures of altered states of consciousness obtained after ketamine exposure. Sensor- and source-level EEG changes were analysed with a focus on spectral power and regional changes. RESULTS: Ketamine-induced altered states were characterised predominantly by dissociative experiences such as disembodiment and ego transcendence; sensory disturbances were also common. Ketamine broadly decreased low-frequency power, with mean reductions largest at alpha (8-12 Hz) in parietal (-0.94 dB, P<0.001) and occipital (-1.8 dB, P<0.001) channel clusters. Significant decreases in alpha were identified in the precuneus and temporal-parietal junction. CONCLUSIONS: Ketamine induces altered states of consciousness during periods of reduced alpha power in the precuneus and temporal-parietal junction. Modulation of these temporal-parietal loci are candidate mechanisms of the psychoactive effects of ketamine, given that this region is involved in multisensory integration, body representation, and consciousness.

Human neural correlates of sevoflurane-induced unconsciousness.

Sevoflurane, a volatile anaesthetic agent well-tolerated for inhalation induction, provides a useful opportunity to elucidate the processes whereby halogenated ethers disrupt consciousness and cognition. Multiple molecular targets of sevoflurane have been identified, complementing imaging and electrophysiologic markers for the mechanistically obscure progression from wakefulness to unconsciousness. Recent investigations have more precisely detailed scalp EEG activity during this transition, with practical clinical implications. The relative timing of scalp potentials in frontal and parietal EEG signals suggests that sevoflurane might perturb the propagation of neural information between underlying cortical regions. Spatially distributed brain activity during general anaesthesia has been further investigated with positron emission tomography (PET) and resting-state functional magnetic resonance imaging (fMRI). Combined EEG and PET investigations have identified changes in cerebral blood flow and metabolic activity in frontal, parietal, and thalamic regions during sevoflurane-induced loss of consciousness. More recent fMRI investigations have revealed that sevoflurane weakens the signal correlations among brain regions that share functionality and specialization during wakefulness. In particular, two such resting-state networks have shown progressive breakdown in intracortical and thalamocortical connectivity with increasing anaesthetic concentrations: the Default Mode Network (introspection and episodic memory) and the Ventral Attention Network (orienting of attention to salient feature of the external world). These data support the hypotheses that perturbations in temporally correlated activity across brain regions contribute to the transition between states of sevoflurane sedation and general anaesthesia.

Patient perspectives on intraoperative awareness with explicit recall: report from a North American anaesthesia awareness registry.

BACKGROUND: Awareness during general anaesthesia is a source of concern for patients and anaesthetists, with potential for psychological and medicolegal sequelae. We used a registry to evaluate unintended awareness from the patient's perspective with an emphasis on their experiences and healthcare provider responses. METHODS: English-speaking subjects self-reported explicit recall of events during anaesthesia to the Anesthesia Awareness Registry of the ASA, completed a survey, and submitted copies of medical records. Anaesthesia awareness was defined as explicit recall of events during induction or maintenance of general anaesthesia. Patient experiences, satisfaction, and desired practitioner responses to explicit recall were based on survey responses. RESULTS: Most of the 68 respondents meeting inclusion criteria (75%) were dissatisfied with the manner in which their concerns were addressed by their healthcare providers, and many reported long-term harm. Half (51%) of respondents reported that neither the anaesthesia provider nor surgeon expressed concern about their experience. Few were offered an apology (10%) or referral for counseling (15%). Patient preferences for responses after an awareness episode included validation of their experience (37%), an explanation (28%), and discussion or follow-up to the episode (26%). CONCLUSIONS: Data from this registry confirm the serious impact of anaesthesia awareness for some patients, and suggest that patients need more systematic responses and follow-up by healthcare providers.

Electroencephalographic coherence and cortical acetylcholine during ketamine-induced unconsciousness. British Journal of Anaesthesia, 2015; 114(6): 979-89, DOI 10.1093/bja/aev095.

This article was published by mistake in the June issue of BJA due to an administrative error. It was supposed to go into this special issue on Memory and Awareness in Anaesthesia. The article can be accessed free of charge at the following link: http://bja.oxfordjournals.org/lookup/doi/10.1093/bja/aev095 The Publisher apologizes for the error.

Electroencephalographic coherence and cortical acetylcholine during ketamine-induced unconsciousness.

BACKGROUND: There is limited understanding of cortical neurochemistry and cortical connectivity during ketamine anaesthesia. We conducted a systematic study to investigate the effects of ketamine on cortical acetylcholine (ACh) and electroencephalographic coherence. METHODS: Male Sprague-Dawley rats (n=11) were implanted with electrodes to record electroencephalogram (EEG) from frontal, parietal, and occipital cortices, and with a microdialysis guide cannula for simultaneous measurement of ACh concentrations in prefrontal cortex before, during, and after ketamine anaesthesia. Coherence and power spectral density computed from the EEG, and ACh concentrations, were compared between conscious and unconscious states. Loss of righting reflex was used as a surrogate for unconsciousness. RESULTS: Ketamine-induced unconsciousness was associated with a global reduction of power (P=0.02) in higher gamma bandwidths (>65 Hz), a global reduction of coherence (P≤0.01) across a broad frequency range (0.5-250 Hz), and a significant increase in ACh concentrations (P=0.01) in the prefrontal cortex. Compared with the unconscious state, recovery of righting reflex was marked by a further increase in ACh concentrations (P=0.0007), global increases in power in theta (4-10 Hz; P=0.03) and low gamma frequencies (25-55 Hz; P=0.0001), and increase in power (P≤0.01) and coherence (P≤0.002) in higher gamma frequencies (65-250 Hz). Acetylcholine concentrations, coherence, and spectral properties returned to baseline levels after a prolonged recovery period. CONCLUSIONS: Ketamine-induced unconsciousness is characterized by suppression of high-frequency gamma activity and a breakdown of cortical coherence, despite increased cholinergic tone in the cortex.

Intraoperative awareness: controversies and non-controversies.

Intraoperative awareness, with or without recall, continues to be a topic of clinical significance and neurobiological interest. In this article, we review evidence pertaining to the incidence, sequelae, and prevention of intraoperative awareness. We also assess which aspects of the complication are well understood (i.e. non-controversial) and which require further research for clarification (i.e. controversial).

Neurological complications of surgery and anaesthesia.

Injury to the central and peripheral nervous systems is often permanent. As such, adverse neurological outcomes of surgery and anaesthesia can be devastating for patients and their families. In this article, we review the incidence, risk factors, outcomes, prevention, and treatment of a number of important neurological complications in the perioperative period.

Minimum alveolar concentration: ongoing relevance and clinical utility.

Since its introduction in 1965, minimum alveolar concentration (MAC) has served as the standard measure of potency for volatile anaesthetic agents. It is defined as the minimum alveolar concentration of inhaled anaesthetic at which 50% of people do not move in response to a noxious stimulus. Within the last 20 years, it has been discovered that volatile anaesthetics inhibit mobility largely through action on the spinal cord, whereas the amnesic and hypnotic effects are mediated by the brain. Studies suggest that the concentration of volatile anaesthetic needed to prevent explicit memory from developing, and to produce unconsciousness, is usually substantially lower than the concentration required to prevent movement in response to surgery. This review highlights the contributions and limitations of MAC and its derivatives as metrics of anaesthetic potency with respect to particular behavioural outcomes. Recent evidence is presented suggesting that a protocol that alerts anaesthetists whenever MAC falls to < 0.5 or 0.7 has the potential to decrease intra-operative awareness with explicit recall, possibly to a similar extent as does a protocol based on processed electroencephalography-driven alerting.

Psychological impact of unexpected explicit recall of events occurring during surgery performed under sedation, regional anaesthesia, and general anaesthesia: data from the Anesthesia Awareness Registry.

BACKGROUND: Anaesthetic awareness is a recognized complication of general anaesthesia (GA) and is associated with post-traumatic stress disorder (PTSD). Although complete amnesia for intraprocedural events during sedation and regional anaesthesia (RA) may occur, explicit recall is expected by anaesthesia providers. Consequently, the possibility that there could be psychological consequences associated with unexpected explicit recall of events during sedation and RA has not been investigated. This study investigated the psychological sequelae of unexpected explicit recall of events during sedation/RA that was reported to the Anesthesia Awareness Registry. METHODS: The Registry recruited subjects who self-identified as having had anaesthetic awareness. Inclusion criteria were a patient-reported awareness experience in 1990 or later and availability of medical records. The sensations experienced by the subjects during their procedure and the acute and persistent psychological sequelae attributed to this explicit recall were assessed for patients receiving sedation/RA and those receiving GA. RESULTS: Among the patients fulfilling the inclusion criteria, medical record review identified 27 sedation/RA and 50 GA cases. Most patients experienced distress (78% of sedation/RA vs 94% of GA). Approximately 40% of patients with sedation/RA had persistent psychological sequelae, similar to GA patients. Some sedation/RA patients reported an adverse impact on their job performance (15%), family relationships (11%), and friendships (11%), and 15% reported being diagnosed with PTSD. CONCLUSIONS: Patients who self-reported to the Registry unexpected explicit recall of events during sedation/RA experienced distress and persistent psychological sequelae comparable with those who had reported anaesthetic awareness during GA. Further study is warranted to determine if patients reporting distress with explicit recall after sedation/RA require psychiatric follow-up.