Feasibility of Prone Positioning for Brain-injured Patients with Severe Acute Respiratory Distress Syndrome: A Systematic Review and Pilot Study (ProBrain).

BACKGROUND: Prone position is a key component to treat hypoxemia in patients with severe acute respiratory distress syndrome. However, most studies evaluating it exclude patients with brain injuries without any medical evidence. METHODS: This study includes a systematic review to determine whether brain-injured patients were excluded in studies evaluating prone position on acute respiratory distress syndrome; a prospective study including consecutive brain-injured patients needing prone position. The primary endpoint was the evaluation of cerebral blood flow using transcranial Doppler after prone positioning. Secondary outcomes were intracranial pressure, cerebral perfusion pressure, and tissue oxygen pressure. RESULTS: From 8,183 citations retrieved, 120 studies were included in the systematic review. Among them, 90 studies excluded brain-injured patients (75%) without any justification, 16 included brain-injured patients (4 randomized, 7 nonrandomized studies, 5 retrospective), and 14 did not retrieve brain-injured data. Eleven patients were included in the authors' pilot study. No reduction of cerebral blood flow surrogates was observed during prone positioning, with diastolic speed values (mean ± SD) ranging from 37.7 ± 16.2 cm/s to 45.2 ± 19.3 cm/s for the right side (P = 0.897) and 39.6 ± 18.2 cm/s to 46.5 ± 21.3 cm/s for the left side (P = 0.569), and pulsatility index ranging from 1.14 ± 0.31 to 1.0 ± 0.32 for the right side (P = 0.145) and 1.14 ± 0.31 to 1.02 ± 0.2 for the left side (P = 0.564) before and during prone position. CONCLUSIONS: Brain-injured patients are largely excluded from studies evaluating prone position in acute respiratory distress syndrome. However, cerebral blood flow seems not to be altered considering increasing of mean arterial pressure during the session. Systematic exclusion of brain-injured patients appears to be unfounded, and prone position, while at risk in brain-injured patients, should be evaluated on these patients to review recommendations, considering close monitoring of neurologic and hemodynamic parameters.

Prognostic value of early EEG abnormalities in severe stroke patients requiring mechanical ventilation: a pre-planned analysis of the SPICE prospective multicenter study.

INTRODUCTION: Prognostication of outcome in severe stroke patients necessitating invasive mechanical ventilation poses significant challenges. The objective of this study was to assess the prognostic significance and prevalence of early electroencephalogram (EEG) abnormalities in adult stroke patients receiving mechanical ventilation. METHODS: This study is a pre-planned ancillary investigation within the prospective multicenter SPICE cohort study (2017-2019), conducted in 33 intensive care units (ICUs) in the Paris area, France. We included adult stroke patients requiring invasive mechanical ventilation, who underwent at least one intermittent EEG examination during their ICU stay. The primary endpoint was the functional neurological outcome at one year, determined using the modified Rankin scale (mRS), and dichotomized as unfavorable (mRS 4-6, indicating severe disability or death) or favorable (mRS 0-3). Multivariable regression analyses were employed to identify EEG abnormalities associated with functional outcomes. RESULTS: Of the 364 patients enrolled in the SPICE study, 153 patients (49 ischemic strokes, 52 intracranial hemorrhages, and 52 subarachnoid hemorrhages) underwent at least one EEG at a median time of 4 (interquartile range 2-7) days post-stroke. Rates of diffuse slowing (70% vs. 63%, p = 0.37), focal slowing (38% vs. 32%, p = 0.15), periodic discharges (2.3% vs. 3.7%, p = 0.9), and electrographic seizures (4.5% vs. 3.7%, p = 0.4) were comparable between patients with unfavorable and favorable outcomes. Following adjustment for potential confounders, an unreactive EEG background to auditory and pain stimulations (OR 6.02, 95% CI 2.27-15.99) was independently associated with unfavorable outcomes. An unreactive EEG predicted unfavorable outcome with a specificity of 48% (95% CI 40-56), sensitivity of 79% (95% CI 72-85), and positive predictive value (PPV) of 74% (95% CI 67-81). Conversely, a benign EEG (defined as continuous and reactive background activity without seizure, periodic discharges, triphasic waves, or burst suppression) predicted favorable outcome with a specificity of 89% (95% CI 84-94), and a sensitivity of 37% (95% CI 30-45). CONCLUSION: The absence of EEG reactivity independently predicts unfavorable outcomes at one year in severe stroke patients requiring mechanical ventilation in the ICU, although its prognostic value remains limited. Conversely, a benign EEG pattern was associated with a favorable outcome.

One-Year Outcomes in Patients With Acute Stroke Requiring Mechanical Ventilation.

BACKGROUND: Long-term outcomes of patients with severe stroke remain poorly documented. We aimed to characterize one-year outcomes of patients with stroke requiring mechanical ventilation in the intensive care unit (ICU). METHODS: We conducted a prospective multicenter cohort study in 33 ICUs in France (2017-2019) on patients with consecutive strokes requiring mechanical ventilation for at least 24 hours. Outcomes were collected via telephone interviews by an independent research assistant. The primary end point was poor functional outcome, defined by a modified Rankin Scale score of 4 to 6 at 1 year. Multivariable mixed models investigated variables associated with the primary end point. Secondary end points included quality of life, activities of daily living, and anxiety and depression in 1-year survivors. RESULTS: Among the 364 patients included, 244 patients (66.5% [95% CI, 61.7%-71.3%]) had a poor functional outcome, including 190 deaths (52.2%). After adjustment for non-neurological organ failure, age ≥70 years (odds ratio [OR], 2.38 [95% CI, 1.26-4.49]), Charlson comorbidity index ≥2 (OR, 2.01 [95% CI, 1.16-3.49]), a score on the Glasgow Coma Scale <8 at ICU admission (OR, 3.43 [95% CI, 1.98-5.96]), stroke subtype (intracerebral hemorrhage: OR, 2.44 [95% CI, 1.29-4.63] versus ischemic stroke: OR, 2.06 [95% CI, 1.06-4.00] versus subarachnoid hemorrhage: reference) remained independently associated with poor functional outcome. In contrast, a time between stroke diagnosis and initiation of mechanical ventilation >1 day was protective (OR, 0.56 [95% CI, 0.33-0.94]). A sensitivity analysis conducted after exclusion of patients with early decisions of withholding/withdrawal of care yielded similar results. We observed persistent physical and psychological problems at 1 year in >50% of survivors. CONCLUSIONS: In patients with severe stroke requiring mechanical ventilation, several ICU admission variables may inform caregivers, patients, and their families on post-ICU trajectories and functional outcomes. The burden of persistent sequelae at 1 year reinforces the need for a personalized, multi-disciplinary, prolonged follow-up of these patients after ICU discharge. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03335995.

Non-ischemic cerebral enhancing lesions after thrombectomy: a multicentric retrospective French national registry.

To report the occurrence of non-ischemic cerebral enhancing (NICE) lesions following mechanical thrombectomy (MT) through the retrospective French nationwide registry of NICE lesions. All thrombectomy capable stroke centers (TSC) in France were invited to fill out a questionnaire disseminated through a trainee-led research network (JENI-RC: Jeunes en Neuroradiologie Interventionnelle-Research Collaborative). NICE lesions were defined according to previous literature as delayed onset punctate, nodular, or annular foci enhancements with peri-lesion edema and vascular distribution in the territory of the MT with no other confounding disease. All 43 TSC French centers responded. Three patients were reported by 3 different centers over a total of 34,824 MT (2015-2020). Patient no. 1 developed symptomatic NICE lesions 8 weeks after MT with combination of aspiration and stentriever for a right middle cerebral artery occlusion. Patient no. 2 developed asymptomatic NICE lesions 5 weeks after MT with direct thromboaspiration for a right middle cerebral artery occlusion. Patient no. 3 developed symptomatic NICE lesions 6 weeks after MT with direct thromboaspiration, and combination of aspiration and stentriever for a basilar artery occlusion. This study provides evidence that NICE lesions following MT are a possible rare complication with a similar presentation as previously described following endovascular aneurysm treatment. Both radiologists and neurologists should be aware of this adverse event and make use of MRI contrast agents in case of unexplained symptoms/images during follow-up after MT.

Procedural Sedation With Dexmedetomidine in Combination With Ketamine in the Emergency Department.

BACKGROUND: Dexmedetomidine is an alternative agent for procedural sedation in the emergency department thanks to its ability to maintain hemodynamic and respiratory stability. Dexmedetomidine must, however, be combined with a powerful analgesic. OBJECTIVE: Our aim was to evaluate the quality and safety of procedural sedation using the combination of dexmedetomidine and ketamine for patients undergoing painful procedures in the emergency department. METHODS: This prospective interventional single-center study was conducted in an academic emergency department of an urban hospital in Brussels, Belgium. Patients received a bolus injection of 1 µg/kg dexmedetomidine over 10 min and then a continuous infusion of 0.6 µg/kg/h followed by a bolus of 1 mg/kg ketamine. The painful procedure was carried out 1 min later. The level of pain was evaluated with a numerical rating scale from 0 (no pain) to 10 (maximal pain). The level of patient comfort for the procedure was measured using a comfort scale. RESULTS: Thirty patients were included. Overall, 90% of patients felt little or no pain (n = 29 of 30) or discomfort (n = 28 of 30) during the procedure. One patient experienced apnea with desaturation, which was resolved by a jaw-thrust maneuver. Although 23% of patients had significant arterial hypertension, none required drug treatment. CONCLUSIONS: The combination of dexmedetomidine and ketamine provides conscious sedation, bringing comfort and pain relief to patients in optimal conditions for respiratory and hemodynamic safety. However, sedation and recovery times are longer than with conventional drug combinations. The dexmedetomidine-ketamine combination should therefore be recommended for nonurgent procedures and fragile patients.

Improving the performance of a triage scale for chest pain patients admitted to emergency departments: combining cardiovascular risk factors and electrocardiogram.

BACKGROUND: The triage of patients presenting with chest pain on admission to the emergency department uses scales based on patient clinical presentation or an electrocardiogram (ECG). These scales have different sensitivity and specificity. Although a good sensitivity allows for the prompt identification of high-risk patients, specificity prevent ED overcrowding. Moreover, ECG at triage avoids missing ST elevation myocardial infarction, which requires urgent revascularization. Our study therefore aimed to investigate whether a scale combining ECG and cardiovascular risk factors (CVRF) improves the diagnostic performance of ED chest pain triage scale. METHODS AND RESULTS: In this prospective single-center observational study involving 505 patients, the standard ECG-based FRENCH scale was compared to a scale combining the ECG-based FRENCH scale and the patients CVRF. The new scale was called the "modified" FRENCH. The accuracy of patient CVRF collection was evaluated by comparing the results of triage nurses and ED physicians. Compared with the standard FRENCH scale, the modified FRENCH scale had an increased sensitivity (61% versus 75%) but a decrease in specificity (76% versus 64%) resulting in a similar diagnostic performance. Using CVRF collected by the ED physicians, the modified FRENCH scale had a sensitivity of 87% and a specificity of 56% with a significant improvement in his diagnostic performance compared with standard FRENCH scales. This improvement can be explained by an accurate collection of the CVRF by physicians compared with nurses, as suggested by the weak to moderate correlation between their respective data collection. CONCLUSION: In conclusion, combining ECG and accurately collected cardiovascular risks factor improves the diagnostic performance of the ECG based chest pain triage in the ED. TRIAL REGISTRATION: Trial registration number: NCT03913767 .

Impact of Proactive Nurse Participation in ICU Family Conferences: A Mixed-Method Study.

OBJECTIVES: To investigate family perceptions of having a nurse participating in family conferences and to assess the psychologic well being of the same families after ICU discharge. DESIGN: Mixed-method design with a qualitative study embedded in a single-center randomized study. SETTING: Twelve-bed medical-surgical ICU in a 460-bed tertiary hospital. SUBJECTS: One family member for each consecutive patient who received more than 48 hours of mechanical ventilation in the ICU. INTERVENTION: Planned proactive participation of a nurse in family conferences led by a physician. In the control group, conferences were led by a physician without a nurse. MEASUREMENTS AND MAIN RESULTS: Of the 172 eligible family members, 100 (60.2%) were randomized; among them, 88 underwent semistructured interviews at ICU discharge and 86 completed the Peritraumatic Dissociative Experiences Questionnaire at ICU discharge and then the Hospital Anxiety Depression Questionnaire and the Impact of Event Scale (for posttraumatic stress-related symptoms) 3 months later. The intervention and control groups were not significantly different regarding the prevalence of posttraumatic stress-related symptoms (52.3 vs 50%, respectively; p = 0.83). Anxiety and depression subscale scores were significantly lower in the intervention group. The qualitative data indicated that the families valued the principle of the conference itself. Perceptions of nurse participation clustered into four main themes: trust that ICU teamwork was effective (50/88; 56.8%), trust that care was centered on the patient (33/88; 37.5%), trust in effective dissemination of information (15/88; 17%), and trust that every effort was made to relieve anxiety in family members (12/88; 13.6%). CONCLUSIONS: Families valued the conferences themselves and valued the proactive participation of a nurse. These positive perceptions were associated with significant anxiety or depression subscale scores but not with changes in posttraumatic stress-related symptoms.

Phenomenologic analysis of healthcare worker perceptions of intensive care unit diaries.

INTRODUCTION: Studies have reported associations between diaries kept for intensive care unit (ICU) patients and long-term quality-of-life and psychological outcomes in patients and their relatives. Little was known about perceptions of healthcare workers reading and writing in the diaries. We investigated healthcare worker perceptions the better to understand their opinions and responses to reading and writing in the diaries. METHODS: We used a phenomenologic approach to conduct a qualitative study of 36 semistructured interviews in a medical-surgical ICU in a 460-bed tertiary hospital. RESULTS: Two domains of perception were assessed: reading and writing in the diaries. These two domains led to four main themes in the ICU workers' perceptions: suffering of the families; using the diary as a source of information for families but also as generating difficulties in writing bad news; determining the optimal interpersonal distance with the patient and relatives; and using the diary as a tool for constructing a narrative of the patient's ICU stay. CONCLUSIONS: The ICU workers thought that the diary was beneficial in communicating the suffering of families while providing comfort and helping to build the patient's ICU narrative. They reported strong emotions related to the diaries and a perception of intruding into the patients' and families' privacy when reading the diaries. Fear of strong emotional investment may adversely affect the ability of ICU workers to perform their duties optimally. ICU workers are in favor of ICU diaries, but activation by the diaries of emotions among younger ICU workers may require specific support.

Relevance of early management by proton-pump inhibitor in acute upper gastro-intestinal tract disorder: A scoping review.

BACKGROUND: Proton-pump inhibitors (PPI) are frequently used in the emergency and general practice settings in several clinical presentations linked to acute upper gastro-intestinal tract disorders as abdominal or chest pain without recommendations. OBJECTIVE: The aim of this scoping review was to assess pain reduction, diagnostic performance, and safety in the first 24 h-management in primary care or emergency medicine. METHODS: Search was realized by 2 independent reviewers in PubMed, Embase, and Web of Science following PRISMA-ScR guidelines. Only original articles or systematic reviews in English were included. Studies about chronic and/or bleeding conditions, therapeutic cocktails and studies without pain evaluation were excluded. Two methodologies were used for bias estimation. RESULTS: From 4442 titles, 79 full-text articles were assessed, and 9 were included. There is no strong evidence supporting the use of PPI as a first line analgesic or diagnostic test in acute syndromes linked to acute upper gastro-intestinal tract disorder. A small effect in pain reduction was retrieved in patients with low pain scores. A poor additional value in patients with gastric reflux, and a low specificity compared to other diagnostic tests were observed. A short-term PPI administration appears to be safe with low risk of serious allergic reactions, and poor adverse effects (moderate evidence). CONCLUSION: Although PPIs may contribute to the multimodal analgesia in acute settings, with few and/or minor side effects, no recommendation can be drawn for their use as a primary analgesic. Data regarding the relevance of the PPI test are much less clear, no data regarding care pathways are available.

Comparison between pupillometry and numeric pain rating scale for pain assessments in communicating adult patients in the emergency department.

OBJECTIVE: The adequate assessment of pain in the emergency department (ED) can be challenging. Two dynamic pupillary measures used in conscious subjects after a surgical procedure were previously shown to correlate to the magnitude of ongoing pain. The objective of this study was to test the ability of dynamic measures derived from pupillometry to evaluate pain intensity in conscious adult patients admitted to the ED. METHODS: This prospective, interventional, single-centre study was performed between August 2021 and January 2022 (NCT05019898). An assessment of self-reported pain intensity was performed on ED admission by the triage nurse using a numeric rating scale (NRS). This was followed by two dynamic measures derived from pupillometry that were previously correlated with pain perception: the pupillary unrest under ambient light (PUAL) and the pupillary light reflex (PLR). RESULTS: Among the 313 analysed patients, the median age was 41 years, and 52% were women. No correlation was found between self-reported pain ratings and PUAL (r = 0.007) or PLR (baseline diameter r = -0.048; decrease r = 0.024; latency r = 0.019; slope = -0.051). Similarly, the pupillometry measures could not discriminate patients with moderate to severe pain (defined as NRS ≥4). CONCLUSIONS: Pupillometry does not appear to be an effective tool to evaluate pain in the ED environment. Indeed, too many factors influencing the sympathetic system-and thus the dynamic pupillary measures-are not controllable in the ED. SIGNIFICANCE: Pupillometry does not appear to be an effective tool to evaluate pain in the ED environment. There are several possible explanations for these negative results. The factors influencing the sympathetic system-and thus the PD fluctuations-are controllable in the postoperative period but not in the ED (e.g. full bladder, hypothermia). In addition, numerous psychological phenomena can impact pupillometry measurements such as emotional reactions or cognitive tasks. These phenomena are particularly difficult to control in the ED environment.

Ethical Management of COVID-19 Pandemic at a Neurological Hospital: The Ethicovid Report.

BACKGROUND: During the first wave of the coronavirus disease-2019 (COVID-19) pandemic, it was necessary to prepare for the possibility of triaging patients who could benefit from access to an intensive care unit (ICU). In our neuroscience institution, the challenge was to continue to manage usual neurological emergencies as well as the influx of COVID-19 patients. METHODS: We report the experience of an ethical consulting unit to support care clinical decisions during the first wave of the pandemic (March 16 to April 30, 2020). Three objective evaluation criteria were defined: 2 of these criteria, patient's factors and general disease severity (Simplified Acute Physiology Score II), were common to all patients, and the third was the specific severity of the disease (neurological for brain injury, respiratory for COVID-19). Given our scarce resources, we used a high probability of a 3-month modified Rankin Scale ≤3 as the criterion for further resuscitation and management. RESULTS: A total of 295 patients were admitted during the first pandemic wave; 111 with COVID-19 and 184 with neurological emergencies. The ethical unit's expertise was sought for 75 clinical situations in 56 patients (35 COVID-19 and 21 neurological). Decisions were as follows: 11% no limitation on care, 5% expectant care with reassessment (maximum therapy to assess possible progress pending decision), 67% partial limitation (no intensification of care or no transfer to ICU), and 17% limitation of curative care. At no time did a lack of availability of ICU beds require the ethical unit to advise against admission to the ICU. CONCLUSIONS: Our ethical consulting unit allowed for collegial ethical decision-making in line with international recommendations. This model could be easily transferred to other triage situations, provided it is adapted to the local context.

A case of daptomycin-induced immune thrombocytopenia.

We report a case of severe daptomycin-induced immune thrombocytopenia in a patient treated for methicillin-resistant Staphylococcus epidermidis and ampicillin-resistant Enterococcus faecalis bacteremia acquired in an intensive care unit. Serum antibodies bound to platelets in the presence of daptomycin on flow cytometry. There was no evidence of other causes of thrombocytopenia. The patient died of brain herniation complicating extensive cerebral hemorrhage. To our knowledge, this is the first described case of daptomycin-induced thrombocytopenia.

Herpes simplex encephalitis: A new type of "ICU-acquired infection"?

PURPOSE: Although it is a well-known disease, the occurrence of Herpes simplex encephalitis (HSE) during a hospital stay may render the diagnosis particularly challenging. The objective of this report is to alert clinicians about the diagnostic pitfalls arising from hospital-developed HSE. MATERIALS AND METHODS: Clinical observation of one patient. CASE REPORT: An 87-year-old male was admitted to the Intensive Care Unit (ICU) because of respiratory failure due to an exacerbation of myasthenia gravis. After corticoids and azathioprine treatment, his clinical condition improved, allowing weaning from mechanical ventilation. One month after admission, while still hospitalized in the ICU, the patient developed fever and confusion. In the context of confounding factors, HSE was not suspected before a convulsive status epilepticus occurred, resulting in a significant delay in treatment. Diagnosis was confirmed by PCR-analysis in the cerebrospinal fluid. Serological status confirmed reactivation of prior herpes simplex infection. The patient died one week after the onset of confusion. CONCLUSIONS: Hospital-"acquired" HSE must be suspected in case of new neurologic symptoms associated with fever, even in ICU-hospitalized patients. The diagnosis is made even more difficult by nonspecific symptoms due to previous diseases, leading to an even more severe prognosis in those vulnerable patients.

Treatment intensity and outcome of nonagenarians selected for admission in ICUs: a multicenter study of the Outcomerea Research Group.

BACKGROUND: Outcome of very elderly patients admitted in intensive care unit (ICU) was most often reported for octogenarians. ICU admission demands for nonagenarians are increasing. The primary objective was to compare outcome and intensity of treatment of octogenarians and nonagenarians. METHODS: We performed an observational study in 12 ICUs of the Outcomerea™ network which prospectively upload data into the Outcomerea™ database. Patients >90 years old (case patients) were matched with patients 80-90 years old (control patients). Matching criteria were severity of illness at admission, center, and year of admission. RESULTS: A total of 2419 patients aged 80 or older and admitted from September 1997 to September 2013 were included. Among them, 179 (7.9 %) were >90 years old. Matching was performed for 176 nonagenarian patients. Compared with control patients, case patients were more often hospitalized for unscheduled surgery [54 (30.7 %) vs. 42 (23.9 %), p < 0.01] and had less often arterial monitoring for blood pressure [37 (21 %) vs. 53 (30.1 %), p = 0.04] and renal replacement therapy [5 (2.8 %) vs. 14 (8 %), p = 0.05] than control patients. ICU [44 (25 %) vs. 36 (20.5 %), p = 0.28] or hospital mortality [70 (39.8 %) vs. 64 (36.4 %), p = 0.46] and limitation of life-sustaining therapies were not significantly different in case versus control patients, respectively. Only 16/176 (14 %) of case patients were transferred to a geriatric unit. CONCLUSION: This multicenter study reported that nonagenarians represented a small fraction of ICU patients. When admitted, these highly selected patients received similar life-sustaining treatments, except RRT, than octogenarians. ICU and hospital mortality were similar between the two groups.

Writing in and reading ICU diaries: qualitative study of families' experience in the ICU.

PURPOSE: Keeping an ICU patient diary has been reported to benefit the patient's recovery. Here, we investigated the families' experience with reading and writing in patient ICU diaries kept by both the family and the staff. METHODS: We conducted a qualitative study involving 32 semi-structured in-depth interviews of relatives of 26 patients (34% of all family members who visited patients) who met our ICU-diary criterion, i.e., ventilation for longer than 48 hours. Grounded theory was used to conceptualise the interview data via a three-step coding process (open coding, axial coding, and selective coding). RESULTS: Communicative, emotional, and humanising experiences emerged from our data. First, family members used the diaries to access, understand, and assimilate the medical information written in the diaries by staff members, and then to share this information with other family members. Second, the diaries enabled family members to maintain a connection with the patient by documenting their presence and expressing their love and affection. Additionally, families confided in the diaries to maintain hope. Finally, family members felt the diaries humanized the medical staff and patient. CONCLUSIONS: Our findings indicate positive effects of diaries on family members. The diaries served as a powerful tool to deliver holistic patient- and family-centered care despite the potentially dehumanising ICU environment. The diaries made the family members aware of their valuable role in caring for the patient and enhanced their access to and comprehension of medical information. Diaries may play a major role in improving the well-being of ICU-patient families.

In vivo selection of biocompatible alginates for islet encapsulation and subcutaneous transplantation.

Islet encapsulation requires several properties including (1) biocompatibility, (2) immunoprotection, and (3) oxygen diffusion for islet survival and diabetes correction. New chemical alginates were tested in vivo and compared with traditional high-mannuronate and -guluronate alginates. New alginates with coupled peptide sequence (sterile lyophilized high mannuronate [SLM]-RGD3% and sterile lyophilized high guluronate [SLG]-RGD3%), to improve encapsulated cell adherence in the matrix, and alginates with a very low viscosity (VLDM7% and VLDG7%), to reduce implant size by loading a higher number of islets per volume of polymer, were implanted subcutaneously in 70 Wistar rats for comparison with alginates of high viscosity and high content of mannuronic (SLM3%) or guluronic acids (SLG3%). Permeability of alginates to 36-, 75-, and 150-kDa lectins coupled to fluorescein isothiocynate was quantified before implantation and at 2, 4, and 12 weeks after implantation. Biocompatibility (fibrosis, graft stability, immunologic infiltration by CD3/CD68 cells, and neovascularization) was assessed at each explantation time. Permeability to small molecules was found for all alginates. Impermeability to 150-kDa molecules, such as IgG, was observed only for SLM3% before implantation and was maintained up to 12 weeks after implantation. SLM3% and SLG3% demonstrated better graft stability with lower CD3/CD68 recruitment and fibrosis than the other alginates. SLM3% induced a significantly higher angiogenesis and maintained oxygen pressure at approximately 40 mm Hg for up to 4 weeks after implantation as measured by in vivo electronic paramagnetic resonance oximetry. SLM-encapsulated pig islets implanted subcutaneously in rats demonstrated no inflammatory/immunologic reactions and islets functioned for up to 60 days without immunosuppression. A traditional alginate made of high mannuronic content (SLM3%) is an adapted material to immunoprotect islets in subcutaneous tissue. No improvement was found with lower viscosity and use of GRGDSP-peptide sequence.