Neuropsychological outcomes after pulmonary endarterectomy using moderate hypothermia and periodic circulatory arrest.

BACKGROUND: In this prospective, single-center, observational study, we investigated the association between repeated short periods of circulatory arrest with moderate hypothermia during pulmonary endarterectomy (PEA) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and different neuropsychological dimensions. METHODS: We examined 70 patients with CTEPH, >18 to 80 years of age, who had been treated with PEA. Neuropsychological testing was performed. RESULTS: Learning ability and delayed memory remained well within the normal range for patients' age. We found a statistically significant post-surgical improvement in motor speed, which was accompanied by a better quality of life and reduced symptoms of depression and anxiety. CONCLUSION: PEA with repeated short periods of circulatory arrest in CTEPH did not result in any neuropsychological complications and may even lead to post-surgical psychological improvements.

Exploring Parent Experience of Communication About Therapeutic Hypothermia in the Neonatal Intensive Care Unit.

BACKGROUND: The unique communication challenges faced by parents of infants undergoing therapeutic hypothermia have not been well characterized. PURPOSE: To develop awareness of communication challenges experienced by families of infants treated with therapeutic hypothermia. METHODS: Semistructured interviews were conducted in a group setting with parents matched into groups according to the severity of the infant's presenting encephalopathy. The interviews were transcribed and coded into principal and additional subthemes. RESULTS: Thirty adults were interviewed including 15 mothers, 12 fathers, 2 grandmothers, and 1 grandfather. The 15 infants were between 2 and 24 months of age at the time of the interviews. The principal theme of communication included the following 3 subthemes; transparency, consistency, and delivery style. Parents reported a strong desire for improved early and transparent communication about therapeutic hypothermia, particularly during transfer from an outside hospital. Parents also reported a preference for consistent communication and highlighted parental touch of the hypothermic infant, obstetrical nurse-to-neonatal intensive care unit nurse communication, and parent and visitor presence in the infant's room as areas in need of greater communication consistency. Parents valued direct and compassionate communication styles that excluded medical jargon. IMPLICATIONS FOR PRACTICE: All providers can implement recommendations for communication to parents of infants treated with therapeutic hypothermia by increasing transparency, developing greater consistency in the communication delivered, and employing a direct and compassionate style to improve the parental experience of therapeutic hypothermia. IMPLICATIONS FOR RESEARCH: Further investigation is needed into the specific challenges parents face with a lack of transparent communication prior to the transfer of an infant for therapeutic hypothermia.

Experiences of surviving a cardiac arrest after therapeutic hypothermia treatment. An interview study.

BACKGROUND: Cardiac arrest (CA) is often associated with high mortality. In Sweden, it is reported that 13-52 per 100,000 people suffer out-of-hospital CA, and survival to one month is 2-14%. OBJECTIVE: This study aimed to describe people's experiences of surviving a CA after therapeutic hypothermia treatment. METHOD: A descriptive qualitative design was used. Data were collected through individual interviews with seven CA survivors. The collected data were analyzed using qualitative content analysis. RESULTS: The analysis resulted in six subthemes and three emerging themes. The themes were "Dealing with issues of mortality", "Living a changed life", and "Being confident with health care and family members". CONCLUSION: Surviving a CA after therapeutic hypothermia treatment means having to deal with issues of mortality, and these patients face a turning point in life. The near-death event can create regression or progression in ethos among these patients. RELEVANCE TO CLINICAL PRACTICE: This study implies that persons who have survived a CA need support to cope. One way to provide support might be to initially establish an individualized health care plan, including bringing up existential issues and involving family members in such conversations.

A Comparison of 2 Practical Cooling Methods on Cycling Capacity in the Heat.

CONTEXT: Cooling the torso and neck can improve exercise performance and capacity in a hot environment; however, the proposed mechanisms for the improvements often differ. OBJECTIVE: To directly compare the effects of cooling the neck and torso region using commercially available devices on exercise capacity in a hot environment (temperature = 35°C ± 0.1°C, relative humidity = 50.1% ± 0.7%). DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Eight recreationally active, nonheat-acclimated men (age = 24 ± 4 years, height = 1.82 ± 0.10 m, mass = 80.3 ± 9.7 kg, maximal power output = 240 ± 25 W). INTERVENTION(S): Three cycling capacity tests at 60% maximal power output to volitional exhaustion: 1 with no cooling (NC), 1 with vest cooling (VC), and 1 with a neck cooling collar (CC). MAIN OUTCOME MEASURE(S): Time to volitional exhaustion, rectal temperature, mean skin temperature, torso and neck skin temperature, body mass, heart rate, rating of perceived exertion, thermal sensation, and feeling scale were measured. RESULTS: Participants cycled longer with VC (32.2 ± 9.5 minutes) than NC (27. 6 ± 7.6 minutes; P = .03; d = 0.54) or CC (30.0 ± 8.8 minutes; P = .02; d = 0.24). We observed no difference between NC and CC (P = .12; d = 0.31). Neck and torso temperature and perceived thermal sensation were reduced with the use of cooling modalities (P < .001), but no other variables were affected. CONCLUSIONS: Cycling capacity in the heat improved when participants used a commercially available cooling vest, but we observed no benefit from wearing a commercially available CC. The vest and the collar did not alter the heart rate, rectal temperature, skin temperature, or sweat-loss responses to the cycling bout.

Feasibility of cognitive functional assessment in cardiac arrest survivors using an abbreviated laptop-based neurocognitive battery.

Cardiac arrest survivors exhibit varying degrees of neurological recovery even in the setting of targeted temperature management (TTM) use, ranging from severe impairments to making a seemingly full return to neurologic baseline function. We sought to explore the feasibility of utilizing a laptop-based neurocognitive battery to identify more subtle cognitive deficits in this population. In a convenience sample of cardiac arrest survivors discharged with a cerebral performance category (CPC) of 1, we evaluated the use of a computerized neurocognitive battery (CNB) in this group compared to a healthy control normative population. The CNB was designed to test 11 specific neurocognitive domains, including such areas as working memory and spatial processing. Testing was scored for both accuracy and speed. In a feasibility convenience sample of 29 cardiac arrest survivors, the mean age was 52.9±16.7 years; 12 patients received postarrest TTM and 17 did not receive TTM. Patients tolerated the battery well and performed at normative levels for both accuracy and speed on most of the 11 domains, but showed reduced accuracy of working memory and speed of spatial memory with large magnitudes (>1 SD), even among those receiving TTM. Across all domains, including those using speed and accuracy, 7 of the 29 subjects (24%) achieved statistically significant scores lower from the normative population in two or more domains. In this population of CPC 1 cardiac arrest survivors, a sensitive neurocognitive battery was feasible and suggests that specific cognitive deficits can be detected compared to a normative population, despite CPC 1 designation. Such testing might allow improved measurement of outcomes following TTM interventions in future trials.

The effects of neonatal cryoanaesthesia-induced hypothermia on adult emotional behaviour and stress markers in C57BL/6 mice.

Since the early 1930s, deep hypothermia (cryoanaesthesia) has been a useful anaesthetic in several types of surgery on neonatal rodents. Especially against the background of modern techniques in systems neuroscience, the method enjoys again increasing popularity. However, little is known about its effects on the subsequent adult behavioural and physiological profile. To systematically investigate the effects of neonatal cryoanaesthesia on adult basal and emotional behaviour as well as on physiological development, 59 C57BL/6 mouse pups were randomly assigned to one of three treatment groups: Pups of the first group were exposed to the hypothermia treatment (H) on postnatal day 3, while pups of the other two groups served as controls: These pups either remained in the home cage without any intervention (C), or were separated from the mother for 15 min (MS) to differentiate between effects of neonatal isolation alone versus hypothermia that inevitably goes along with neonatal isolation. Subsequent behavioural analyses were conducted during adulthood (P 84-P 130), including tests for exploratory, anxiety-like and depression-like behaviour. At the age of about 145 days mice were decapitated to record BDNF levels in the hippocampus and serum corticosterone. Altogether, H mice were found to display slightly increased anxiety levels on the O-Maze, but did not differ from the control animals in any other behavioural test. Subtle alterations in anxiety-like behaviour, however, were not accompanied by physiological changes in serum corticosterone and hippocampal BDNF levels, arguing against an overall long-lasting effect of neonatal hypothermia on the emotional profile of adult mice.

Experiences of parents whose newborns undergo hypothermia treatment following perinatal asphyxia.

OBJECTIVE: To describe and interpret experiences of parents whose newborns are treated with induced hypothermia following perinatal asphyxia. DESIGN: A qualitative exploratory study. SETTING: Data collection in parental home environments (n = 8) and in a study room in a university library (n = 2). PARTICIPANTS: A total of 10 parents, seven mothers and three fathers, participated in the study. Their newborns were treated with induced hypothermia 4 to 12 months prior to the interviews. METHODS: Recorded open-ended interviews with the participants lasted from 60 to 90 minutes. Field notes were made after each interview. The interviews were transcribed verbatim and inductive content analysis was used in the analyzing process. RESULTS: Four main themes emerged from the data: emotional landscapes, adaptation to a new situation (with subthemes creating control, external and internal support in a difficult situation, normalizing the abnormal and reconciling oneself to uncertainty), moments of rebirth, and change in attitude toward life and existence. CONCLUSION: Term newborns are treated with induced hypothermia treatment due to perinatal asphyxia. During the hospitalization of newborns in neonatal intensive care units (NICUs), parents experience high levels of stress. Parents use several strategies for adapting to this situation, and nurses play a pivotal role in providing individual support and acting as advocates for parents in the NICU. After the infants are rewarmed, parents experience a moment of rebirth that might help them attach to their infants. Further research is warranted in this area to provide holistic care and support to families whose neonates undergo this treatment.

Cognitive dysfunction and health-related quality of life after a cardiac arrest and therapeutic hypothermia.

BACKGROUND: Evidence-based treatment protocols including therapeutic hypothermia have increased hospital survival to over 50% in unconscious out-of-hospital cardiac arrest survivors. In this study we estimated the incidence of cognitive dysfunctions in a group of cardiac arrest survivors with a high functional outcome treated with therapeutic hypothermia. Secondarily, we assessed the cardiac arrest group's level of cognitive performance in each tested cognitive domain and investigated the relationship between cognitive function and age, time since cardiac arrest and health-related quality of life (HRQOL). METHODS: We included 26 patients 13-28 months after a cardiac arrest. All patients were scored using the Cerebral Performance Category scale (CPC) and Mini-Mental State Examination (MMSE). Twenty-five of the patients were tested for cognitive function using the Cambridge Neuropsychological Test Automated Battery (CANTAB). These patients were tested using four cognitive tests: Motor Screening Test, Delayed Matching to Sample, Stockings of Cambridge and Paired Associate Learning from CANTAB. All patients filled in the Short Form-36 for the assessment of HRQOL. RESULTS: Thirteen of 25 (52%) patients were classified as having a cognitive dysfunction. Compared with the reference population, there was no difference in the performance in motor function and delayed memory but there were significant differences in executive function and episodic memory. We found no associations between cognitive function and age, time since cardiac arrest or HRQOL. CONCLUSION: Half of the patients had a cognitive dysfunction with reduced performance on executive function and episodic memory, indicating frontal and temporal lobe affection, respectively. Reduced performance did not affect HRQOL.

Spatio-temporal motifs 'remembered' in neuronal networks following profound hypothermia.

Surgical procedures using hypothermic temperatures have been linked to complications such as seizures, impaired mental development and impaired memory. Although there is some evidence that the profound hypothermia (<12 ( composite function)C) used in these procedures may be contributing to these neurological impairments, skepticism remains because of lack of evidence from experimental studies isolating the effects of hypothermia on neuronal networks. In order to attain a better understanding of profound hypothermia effects on neurons during surgical procedures, we applied cold to a cultured in-vitro neuronal network. The typical pattern of activity of such cultures is in the form of synchronized bursts, in which most of the recorded neurons fire action potentials in a short time period. In most cases, the bursting activity shows one or more repeating precise spatio-temporal patterns (motifs) that are sustained over long periods of time. In this experimental study, neuronal networks grown on microelectrode arrays (MEA) are subjected to profound hypothermia for an hour and the collective dynamics of the network as a whole are assessed. We show, by using a similarity analysis that compares changes in the time delays between neuronal activation at different burst motifs, that neuronal networks survive total inhibition by profound hypothermia and retain their intrinsic synchronized burst motifs even with substantial generalized neuronal degeneration. By applying multiple sessions of cold, we also show a marked monotonic reduction in the rate of burst firing and in the number of spikes of each neuron after each session.

Improving the quality of consent to randomised controlled trials by using continuous consent and clinician training in the consent process.

OBJECTIVE: To assess whether continuous consent, a process in which information is given to research participants at different stages in a trial, and clinician training in that process were effective when used by clinicians while gaining consent to the Total Body Hypothermia (TOBY) trial. The TOBY trial is a randomised controlled trial (RCT) investigating the use of whole-body cooling for neonates with evidence of perinatal asphyxia. Obtaining valid informed consent for the TOBY trial is difficult, but is a good test of the effectiveness of continuous consent. METHODS: Semistructured interviews were conducted with 30 sets of parents who consented to the TOBY trial and with 10 clinicians who sought it by the continuous consent process. Analysis was focused on the validity of parental consent based on the consent components of competence, information, understanding and voluntariness. RESULTS: No marked problems with consent validity at the point of signature were observed in 19 of 27 (70%) couples. Problems were found mainly to lie with the competence and understanding of the parents: mothers, particularly, had problems with competence in the early stages of consent. Problems in understanding were primarily to do with side effects. Problems in both competence and understanding were observed to reduce markedly, particularly for mothers, in the post-signature phase, when further discussion took place. Randomisation was generally understood but unpopular. Information was not always given by clinicians in stages during the short period available before parents gave consent. Most clinicians, however, were able to give follow-up information. DISCUSSION: Consent validity was found to compare favourably with similar trials examined in the Euricon study. CONCLUSION: Adopting the elements of the continuous consent process and clinician training in RCTs should be considered by researchers, particularly when they have concerns about the quality of consent they are likely to obtain by using a conventional process.

A randomized controlled study of the acute and chronic effects of cooling therapy for MS.

BACKGROUND: Cooling demyelinated nerves can reduce conduction block, potentially improving symptoms of MS. The therapeutic effects of cooling in patients with MS have not been convincingly demonstrated because prior studies were limited by uncontrolled designs, unblinded evaluations, reliance on subjective outcome measures, and small sample sizes. OBJECTIVE: To determine the effects of a single acute dose of cooling therapy using objective measures of neurologic function in a controlled, double-blinded setting, and to determine whether effects are sustained during daily cooling garment use. METHODS: Patients (n = 84) with definite MS, mild to moderate disability (Expanded Disability Status Scale score < 6.0), and self-reported heat sensitivity were randomized into a multicenter, sham-treatment controlled, double-blind crossover study. Patients had the MS Functional Composite (MSFC) and measures of visual acuity/contrast sensitivity assessed before and after high-dose or low-dose cooling for 1 hour with a liquid cooling garment. One week later, patients had identical assessments before and after the alternate treatment. Patients were then re-randomized to use the cooling garment 1 hour each day for a month or to have observation only. They completed self-rated assessments of fatigue, strength, and cognition during this time, and underwent another acute cooling session at the end of the period. After 1 week of rest, they had identical assessments during the alternate treatment. RESULTS: Body temperature declined during both high-dose and low-dose cooling, but high-dose produced a greater reduction (p < 0.0001). High-dose cooling produced a small improvement in the MSFC (0.076 +/- 0.66, p = 0.007), whereas low-dose cooling produced only a trend toward improvement (0.053 +/- 0.031, p = 0.09), but the difference between conditions was not significant. Timed gait testing and visual acuity/contrast sensitivity improved in both conditions as well. When patients underwent acute cooling following a month of daily cooling, treatment effects were similar. Patients reported less fatigue during the month of daily cooling, concurrently on the Rochester Fatigue Diary and retrospectively on the Modified Fatigue Impact Scale. CONCLUSIONS: Cooling therapy was associated with objectively measurable but modest improvements in motor and visual function as well as persistent subjective benefits.

Prospective evaluation of verbal memory performance after cardiopulmonary bypass surgery.

One hundred and four patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and a surgical control group undergoing major vascular or thoracic surgery (n = 18) were tested with the Auditory Verbal Learning Test (AVLT) at the following intervals: 1 day before, 1 week after, and 6 months after surgery. Early after surgery a significant decline in AVLT-performance was found, characterized by a smaller carry-over of learned words on subsequent acquisition trials. Six-month follow-up data revealed significant improvement in the delayed retention of words as compared to the preoperative assessment. No surgical group differences or time by group interaction effects were found. In the CPB group, deeper levels of hypothermia, reflecting longer and more extensive cardiac surgery, were associated with reduced improvement on retest.

Cognitive development of children following early repair of transposition of the great arteries using deep hypothermic circulatory arrest.

Twenty-eight children who underwent corrective cardiac surgery in early infancy had developmental evaluations to explore whether cardiopulmonary bypass perfusion variables are associated with later cognitive function. All had transposition of the great arteries repaired by the arterial switch operation using deep hypothermic circulatory arrest. The mean duration of deep hypothermic circulatory arrest was 64 +/- 10 minutes (mean +/- SD). Median age at repair was 4 days (range 1 to 125 days). Tests of development were administered at age 7 to 53 months: Bayley Scales for children younger than 30 months of age (n = 18) and McCarthy Scales for older children (n = 10). Overall cognitive development score was 101.2 +/- 11.1. Duration of deep hypothermic circulatory arrest was not associated with performance. However, for core cooling periods of less than 20 minutes' duration, shorter cooling periods were associated with lower scores (r = .85, n = 11, P less than .001). These data suggest that patients undergoing relatively long periods of deep hypothermic circulatory arrest may require some minimum time of cardiopulmonary bypass cooling to avoid central nervous system injury.