Artificial intelligence and "the Art of Kintsugi" in Anesthesiology: ten influential papers for clinical users

Artificial intelligence refers to the simulation of human intelligence in machines that are programmed to think like humans and mimic their actions. In the present review we chose ten influential papers from the last five years and through Kintsugi, shed the light on recent evolution of artificial intelligence in anesthesiology. A comprehensive search in in Medline, Embase, Web of Science and Scopus databases was conducted. Each author searched the databases independently and created a list of six articles that influenced their clinical practice during this period, with a focus on their area of competence. During a subsequent step, each researcher presented his own list and most cited papers were selected to create the final collection of ten articles. In recent years purely methodological works with a cryptic technology (black-box) represented by the intact and static vessel, translated to a "modern artificial intelligence" in clinical practice and comprehensibility (glass-box). The purposes of this review are to explore the ten most cited papers about artificial intelligence in anesthesiology and to understand how and when it should be integrated in clinical practice.

Prolonged continuous wound infusion of local anesthetic and steroid after major abdominal surgery to reduce opioid consumption: a randomized, double-blind trial

BACKGROUND

Continuous wound infusion (CWI) is effective for post-operative pain management, but the effect of prolonged infusions and the use of steroids in the infused mixture have never been addressed. We investigate the effect of prolonged CWI with ropivacaine 0.2% (R) over seven days and methylprednisolone (Mp) 1 mg/kg infused in the wound in the first 24 hours.

METHODS

This is a randomized, double blind, phase III trial (RCT) in major abdominal surgery with laparotomy. After a 24-hours pre-peritoneal CWI of R-Mp, patients were randomized to receive either R-Mp or placebo for the next 24 hours. Then, patient-controlled CWI with only ropivacaine 0.2% or placebo (according to the randomization group) was planned between 48 hours and seven days after surgery. Morphine equivalents at seven days were analyzed, together with any catheter- or drug-related side effect and PPSP at 3 months.

RESULTS

We enrolled 120 patients (63 in the CWI group, 57 in the placebo group). Prolonged CWI did not reduce opioid consumption in the first seven postoperative days (P=0.08). CWI was associated with reduced consumption of non-opioid analgesics (P=0.03). Most of the patients continued to require bolus in the surgical wound beyond 48 hours. PPSP prevalence was not different between groups.

CONCLUSIONS

Prolonged infusion with R-Mp is safe and effective but did not reduce opioid consumption in the seven days after surgery or PPSP prevalence.

A case of pneumococcal pneumonia and pelvic-peritonitis in a menstrual endovaginal cup user, which came first?

INTRODUCTION

Streptococcus pneumoniae infrequently causes genital tract infections but - in particular predisposing circumstances - it can be a transient part of vaginal flora and thus pelvic infections can occur. Possible conditions associated with pneumococcal pelvic-peritonitis include the use of intrauterine contraceptive devices, recent birth and gynecologic surgery. The underlying mechanism of these occurrences is likely to be the ascending infection from the genital tract via the fallopian tubes.

CASE PRESENTATION

We present a case of pelvic-peritonitis and pneumonia due to Streptococcus pneumoniae in a healthy young woman wearing a menstrual endovaginal cup. Following the radiological findings of a cystic formation in the right ovary and ascites effusions in all peritoneal recesses an emergency exploratory laparoscopy with right ovariectomy was performed. After resolution of abdominal sepsis, parenchymal consolidation complicated into necrotizing pneumonia, hence the patient underwent a right lower lobectomy.

DISCUSSION

The menstrual cup is a self-retaining intravaginal menstrual fluid collection device, considered as a safe alternative to tampons and pads, which use is associated with rare adverse effects. Few cases of infectious disease have been described, where the underlying mechanism may consist of bacterial replication within the blood accumulated in the uterine environment, with subsequent ascension into the genital tract.

CONCLUSION

In the rare occurrence of pneumococcal pelvic-peritonitis considering all possible infectious sources is paramount, as is assessing the possible involvement of intravaginal devices, increasingly used nowadays but of which potential complications are still poorly described.

The Clinical Researcher Journey in the Artificial Intelligence Era: The PAC-MAN’s Challenge

Artificial intelligence (AI) is a powerful tool that can assist researchers and clinicians in various settings. However, like any technology, it must be used with caution and awareness as there are numerous potential pitfalls. To provide a creative analogy, we have likened research to the PAC-MAN classic arcade video game. Just as the protagonist of the game is constantly seeking data, researchers are constantly seeking information that must be acquired and managed within the constraints of the research rules. In our analogy, the obstacles that researchers face are represented by “ghosts”, which symbolize major ethical concerns, low-quality data, legal issues, and educational challenges. In short, clinical researchers need to meticulously collect and analyze data from various sources, often navigating through intricate and nuanced challenges to ensure that the data they obtain are both precise and pertinent to their research inquiry. Reflecting on this analogy can foster a deeper comprehension of the significance of employing AI and other powerful technologies with heightened awareness and attentiveness.

Wireless Peripheral Nerve Stimulation for The Upper Limb: A Case Report

Peripheral neuro-stimulation (PNS) has been proved to be effective for the treatment of neuropathic pain as well as other painful conditions. We discuss two approaches to PNS placement in the upper extremity. The first case describes a neuropathic syndrome after the traumatic amputation of the distal phalanx of the fifth digit secondary to a work accident with lack of responsiveness to a triple conservative therapy. An upper arm region approach for the PNS was chosen. The procedure had a favorable outcome; in fact, after one month the pain symptoms were absent (VAS 0) and the pharmacological therapy was suspended. The second case presented a patient affected by progressive CRPS type II in the sensory regions of the ulnar and median nerve in the hand, unresponsive to drug therapy. For this procedure, the PNS device was implanted in the forearm. Unfortunately, in this second case the migration of the catheter affected the effectiveness of the treatment. After examining the two cases in this paper, we changed our practice and suggest the implantation of PNS for radial, median and/or ulnar nerve stimulation in the upper arm region, which has significant advantages over the forearm region.

Artificial intelligence enhanced ultrasound (AI-US) in a severe obese parturient: a case report

Background

Neuraxial anesthesia in obese parturients can be challenging due to anatomical and physiological modifications secondary to pregnancy; this led to growing popularity of spine ultrasound in this population for easing landmark identification and procedure execution.

Integration of Artificial Intelligence with ultrasound (AI-US) for image enhancement and analysis has increased clinicians' ability to localize vertebral structures in patients with challenging anatomical conformation.

Case presentation

We present the case of a parturient with extremely severe obesity, with a Body Mass Index (BMI) = 64.5 kg/m², in which the AI-Enabled Image Recognition allowed a successful placing of an epidural catheter.

Conclusions

Benefits gained from AI-US implementation are multiple: immediate recognition of anatomical structures leads to increased first-attempt success rate, making easier the process of spinal anesthesia execution compared to traditional palpation methods, reducing needle placement time for spinal anesthesia and predicting best needle direction and target structure depth in peridural anesthesia.

Double epidural catheter technique in a patient with severe COPD undergoing major abdominal surgery: A case report

INTRODUCTION AND IMPORTANCE

Chronic Obstructive Pulmonary Disease (COPD) leads to the development of postoperative pulmonary complications (PPC), such as atelectasis, pneumonia and respiratory failure. The use of epidural anesthesia, alone or combined with general anesthesia, is known to reduce the incidence of PPC and shorten tracheal intubation time. In major procedures involving both the lower and upper abdomen, central neuraxial block at a single level may be inadequate to provide sufficient metameric extension of anesthesia. This limitation could be overcome with the use of double epidural catheter (DEC), has proved effective in diverse surgical scenarios.

CASE PRESENTATION AND CLINICAL DISCUSSION

We present the case of a woman affected by moderate-severe COPD scheduled for major abdominal cytoreductive surgery due to ovarian malignancy with planned xypho-pubic laparotomy. We developed and implemented a DEC-based strategy for perioperative pain management based on the extent of surgical incision and the high risk of difficult weaning from ventilation and PPC. We used intraoperative monitoring to guarantee adequate antinociception throughout the entire 350 min long demolitive surgical procedure. No additional top-ups of intravenous analgesia or neuromuscular blocking agent (NMBA) was needed during surgery; at the end of the procedure, the patient was extubated in the operating theatre, maintaining adequate respiratory function during the whole postoperative period.

CONCLUSIONS

The DEC technique could be beneficial for patients undergoing cytoreductive surgery. In our case, this technique granted optimal analgesic coverage and was instrumental in achieving fast weaning from mechanical ventilation and early tracheal extubation. Systematic studies on this subject are warranted.

Understanding basic principles of Artificial Intelligence: a practical guide for intensivists

BACKGROUND AND AIM

Artificial intelligence was born to allow computers to learn and control their environment, trying to imitate the human brain structure by simulating its biological evolution. Artificial intelligence makes it possible to analyze large amounts of data (big data) in real-time, providing forecasts that can support the clinician's decisions. This scenario can include diagnosis, prognosis, and treatment in anesthesiology, intensive care medicine, and pain medicine. Machine Learning is a subcategory of AI. It is based on algorithms trained for decisions making that automatically learn and recognize patterns from data. This article aims to offer an overview of the potential application of AI in anesthesiology and analyzes the operating principles of machine learning Every Machine Learning pathway starts from task definition and ends in model application.

CONCLUSIONS

High-performance characteristics and strict quality controls are needed during its progress. During this process, different measures can be identified (pre-processing, exploratory data analysis, model selection, model processing and evaluation). For inexperienced operators, the process can be facilitated by ad hoc tools for data engineering, machine learning, and analytics.

Emergently planned exclusive hub-and-spoke system in the epicenter of the first wave of COVID-19 pandemic in Italy: the experience of the largest COVID-19-free ICU hub for time-dependent diseases

BACKGROUND

Lombardy was the epicenter in Italy of the first wave of COVID-19 pandemic. To face the contagion growth, from March 8 to May 8 2020, a regional law re-designed the hub-and-spoke system for time-dependent diseases to better allocate resources for COVID-19 patients.

METHODS

We report the reorganization of the major hospital in Lombardy during COVID-19 pandemic, including the rearrangement of its ICU beds to face COVID-19 pandemic and fulfill its role as extended hub for time-dependent diseases while preserving transplant activity. To highlight the impact of the emergently planned hub-and-spoke system, all patients admitted to a COVID-19-free ICU hub for trauma, neurosurgical emergencies and stroke during the two-month period were retrospectively collected and compared to 2019 cohort. Regional data on organ procurement was retrieved. Observed-to-expected (OE) in-ICU mortality ratios were computed to test the impact of the pandemic on patients affected by time-dependent diseases.

RESULTS

Dynamic changes in ICU resource allocation occurred according to local COVID-19 epidemiology/trends of patients referred for time-dependent diseases. The absolute increase of admissions for trauma, neurosurgical emergencies and stroke was roughly two-fold. Patients referred to the hub were older and characterized by more severe conditions. An increase in crude mortality was observed, though OE ratios for in-ICU mortality were not statistically different when comparing 2020 vs. 2019. An increase in local organ procurement was observed, limiting the debacle of regional transplant activity.

CONCLUSIONS

We described the effects of a regional emergently planned hub-and-spoke system for time-dependent diseases settled in the epicenter of COVID-19 pandemic in Italy.

Past, Present, and Future of Informed Consent in Pain and Genomics Research: Challenges Facing Global Medical Community

In recent decades, there has been a revision of the role of institutional review boards with the intention of protecting human subjects from harm and exploitation in research. Informed consent aims to protect the subject by explaining all of the benefits and risks associated with a specific research project. To date, there has not been a review published analyzing issues of informed consent in research in the field of genetic/Omics in subjects with chronic pain, and the current review aims to fill that gap in the ethical aspects of such investigation. Despite the extensive discussion on ethical challenges unique to the field of genetic/Omics, this is the first attempt at addressing ethical challenges regarding Informed Consent Forms for pain research as the primary focus. We see this contribution as an important one, for while ethical issues are too often ignored in pain research in general, the numerous arising ethical issues that are unique to pain genetic/Omics suggest that researchers in the field need to pay even greater attention to the rights of subjects/patients. This article presents the work of the Ethic Committee of the Pain-Omics Group (www.painomics.eu), a consortium of 11 centers that is running the Pain-Omics project funded by the European Community in the 7th Framework Program theme (HEALTH.2013.2.2.1-5-Understanding and controlling pain). The Ethic Committee is composed of 1 member of each group of the consortium as well as key opinion leaders in the field of ethics and pain more generally.

Mechanisms of low back pain: a guide for diagnosis and therapy

Chronic low back pain (CLBP) is a chronic pain syndrome in the lower back region, lasting for at least 3 months. CLBP represents the second leading cause of disability worldwide being a major welfare and economic problem. The prevalence of CLBP in adults has increased more than 100% in the last decade and continues to increase dramatically in the aging population, affecting both men and women in all ethnic groups, with a significant impact on functional capacity and occupational activities. It can also be influenced by psychological factors, such as stress, depression and/or anxiety. Given this complexity, the diagnostic evaluation of patients with CLBP can be very challenging and requires complex clinical decision-making. Answering the question "what is the pain generator" among the several structures potentially involved in CLBP is a key factor in the management of these patients, since a mis-diagnosis can generate therapeutical mistakes. Traditionally, the notion that the etiology of 80% to 90% of LBP cases is unknown has been mistaken perpetuated across decades. In most cases, low back pain can be attributed to specific pain generator, with its own characteristics and with different therapeutical opportunity. Here we discuss about radicular pain, facet Joint pain, sacro-iliac pain, pain related to lumbar stenosis, discogenic pain. Our article aims to offer to the clinicians a simple guidance to identify pain generators in a safer and faster way, relying a correct diagnosis and further therapeutical approach.

Mechanisms of low back pain: a guide for diagnosis and therapy

Chronic low back pain (CLBP) is a chronic pain syndrome in the lower back region, lasting for at least 3 months. CLBP represents the second leading cause of disability worldwide being a major welfare and economic problem. The prevalence of CLBP in adults has increased more than 100% in the last decade and continues to increase dramatically in the aging population, affecting both men and women in all ethnic groups, with a significant impact on functional capacity and occupational activities. It can also be influenced by psychological factors, such as stress, depression and/or anxiety. Given this complexity, the diagnostic evaluation of patients with CLBP can be very challenging and requires complex clinical decision-making. Answering the question "what is the pain generator" among the several structures potentially involved in CLBP is a key factor in the management of these patients, since a mis-diagnosis can generate therapeutical mistakes. Traditionally, the notion that the etiology of 80% to 90% of LBP cases is unknown has been mistaken perpetuated across decades. In most cases, low back pain can be attributed to specific pain generator, with its own characteristics and with different therapeutical opportunity. Here we discuss about radicular pain, facet Joint pain, sacro-iliac pain, pain related to lumbar stenosis, discogenic pain. Our article aims to offer to the clinicians a simple guidance to identify pain generators in a safer and faster way, relying a correct diagnosis and further therapeutical approach.

Chronic pain treatment and scrambler therapy: a multicenter retrospective analysis

BACKGROUND AND AIM

Scrambler Therapy is a novel neuromodulation that works by electrocutaneous stimulation in a non-invasive manner through C fibers surface receptors. It substitutes pain information with synthetic "non pain" information. The primary aim of this study was to analyze the efficacy and safety of Scrambler Therapy after ten sessions related to different usage conditions and different learning curves that occur in a multi-center study.

METHODS

201 patients have been treated with Scrambler Therapy. All the patients were suffering from chronic pain with a mean pain NRS of 7.41 (SD 2.06) before treatment. Main causes of chronic pain: post herpetic neuralgia 18.40 %, chronic low back pain (LBP) 37.31%, polyneuropathy 10.94%, and peripheral neuropathy 14.42 %. The remaining 18.93 % included chronic pain due to other causes.

RESULTS

The difference between pre-treatment NRS 7.41 (SD 2.06) and post-treatment 1.60 (SD 2.22) was statistically significant (P< 0.0001). The mean number of sessions per patient was 10, but 39 had complete absence of pain sooner and used fewer sessions. Only 7 patients stopped treatment due to lack of results, and 2 for personal reasons not ascribable to the treatment. Stimulation pain score of 0 during treatment, and not just pain reduction, predicts long term effectiveness, so this must be pursued by optimizing electrode positioning and correct fine-tuning of stimulation intensity.

CONCLUSION

Scrambler Therapy is an efficient and safe alternative for several different types of refractory chronic neuropathic pain, with a very rare possibility of adverse events.

Continuous wound infusion of local anesthetic and steroid after major abdominal surgery: study protocol for a randomized controlled trial

Background

Inflammatory response is one of the key components of pain perception. Continuous infusion (CWI) of local anesthetics has been shown to be effective in controlling pain and reducing postoperative morphine consumption, but the effect of adding a potent anti-inflammatory drug (such as a steroid) has never been addressed. In our study, we want to investigate the effect of CWI with local anesthetic + methylprednisolone on acute and persistent pain, correlating clinical data with biomarkers of inflammation and genetic background.

Methods/Design

After approval by their institutional review board, three hospitals will enroll 120 patients undergoing major abdominal surgery in a randomized, double-blind, phase III study. After a 24-h CWI of ropivacaine 0.2 % + methylprednisolone 1 mg/kg, patients will be randomly assigned to receive either ropivacaine + steroid or placebo for the next 24 h. Then, patient-controlled CWI with only ropivacaine 0.2 % or placebo (according to the group of randomization) is planned after 48 h up to 7 days (bolus 10 ml, lock-out 1 h, maximum dose of 40 ml in 4 h). Morphine equivalent consumption up to 7 days will be analyzed, together with any catheter- or drug-related side effect. Persistent post-surgical pain (PPSP) incidence will also be investigated. Our primary endpoint is analgesic consumption in the first 7 days after surgery; we will evaluate, as secondary endpoints, any catheter- or drug-related side effect, genotype/phenotype correlations between some polymorphisms and postoperative outcome in terms of morphine consumption, development of the inflammatory response, and incidence of PPSP. Finally, we will collect, in a subgroup of patients, wound exudate samples by micro-dialysis, blood samples, and urine samples up to 72 h to investigate local and systemic inflammation and oxidative stress.

Discussion

This is a phase III trial to evaluate the safety and efficacy of wound infusion with steroid and local anesthetic. The study is aimed also to evaluate how long this infusion has to be maintained in order to maximize effectiveness. Our data are intended to quantify the amount of ropivacaine and methylprednisolone needed by patients undergoing major abdominal surgery, to be stored in a new nanotechnology device for sustained pain treatment after surgery. We also aim to clarify the roles of inflammatory response, oxidative stress, and genetic background on postoperative and persistent pain after major abdominal surgery.

Trial registration

The trial was registered on ClinicalTrials.gov (NCT02002663) on 24 Oct. 2013.

Opioid use for Chronic Pain Management in Italy: Results from the Orthopedic Instant Pain Survey Project

Pain is a common symptom in orthopedic patients, but is managed sub-optimally, partly due to scarce opioid use in severe cases. The aim of the Orthopedic Instant Pain Survey (POIS) was to evaluate changes in pain management in Italian orthopedic practice 2 years after a legislative change (Law 38/2010) simplifying opioid access for pain control. A web-based survey on the knowledge of this law and trends observed in clinical practice for severe pain treatment was administered to 143 Italian orthopedic specialists. In total, 101 (70%) respondents showed a high level of knowledge. Nevertheless, 54.5% stated that they do not use opioids for severe osteo-articular pain management. Main barriers to opioid use are fear of adverse events (61.4%), especially nausea/vomiting and constipation, and patient resistance (29.7%). A modest knowledge of pain classification was also demonstrated. Opioid use remains very limited in Italian orthopedic practice. Physicians’ fear of side effects showed poor knowledge of strategies for effective management of opioid-related adverse events, such as combined oral prolonged-release oxycodone/naloxone. Continuing educational programs could improve delivery of evidence-based pain management.

Pain assessment in animal models: do we need further studies?

In the last two decades, animal models have become important tools in understanding and treating pain, and in predicting analgesic efficacy. Although rodent models retain a dominant role in the study of pain mechanisms, large animal models may predict human biology and pharmacology in certain pain conditions more accurately. Taking into consideration the anatomical and physiological characteristics common to man and pigs (median body size, digestive apparatus, number, size, distribution and communication of vessels in dermal skin, epidermal-dermal junctions, the immunoreactivity of peptide nerve fibers, distribution of nociceptive and non-nociceptive fiber classes, and changes in axonal excitability), swines seem to provide the most suitable animal model for pain assessment. Locomotor function, clinical signs, and measurements (respiratory rate, heart rate, blood pressure, temperature, electromyography), behavior (bright/quiet, alert, responsive, depressed, unresponsive), plasma concentration of substance P and cortisol, vocalization, lameness, and axon reflex vasodilatation by laser Doppler imaging have been used to assess pain, but none of these evaluations have proved entirely satisfactory. It is necessary to identify new methods for evaluating pain in large animals (particularly pigs), because of their similarities to humans. This could lead to improved assessment of pain and improved analgesic treatment for both humans and laboratory animals.

Paravertebral block for patients older than 80 years in one day surgery elective mastectomy

Paravertebral block (PVB) has been proposed as an alternative to General anaesthesia (GA) for breast surgery. It provides good operative anaesthesia, good pain control with little adverse effects. Six women older than 80 year were selected. All patients were post-operatively interviewed about the presence of pain, nausea and vomiting. All patients declared absence of pain and nausea and that they were satisfied with the procedure. The use of PVB allows elderly patients to undergo ambulatory surgery for the treatment of breast cancer with satisfaction. This technique allows a short recovery and adequate postoperative pain relief with reduced hospital costs.

The management of patients with intradural post-traumatic mass lesions: a multicenter survey of current approaches to surgical management in 729 patients coordinated by the European Brain Injury Consortium

OBJECTIVE

Controversy exists about the indications and timing for surgery in head injured patients with an intradural mass lesion. The aim of this study was to survey contemporary approaches to the treatment of head injured patients with an intradural lesion, placing a particular focus on the utilization of decompressive craniectomy.

METHODS

A prospective international survey was conducted over a 3-month period in 67 centers from 24 countries on the neurosurgical management of head injured patients with an intradural mass lesion and/or radiological signs of raised intracranial pressure. Information was obtained about demographic, clinical, and radiological features; surgical management, and mortality at discharge.

RESULTS

Over the period of the study, data were collected about 729 patients consecutively admitted to one of the participating centers. The survey included 397 patients with a severe head injury (Glasgow Coma Scale [GCS] 3-8), 155 with a moderate head injury (GCS 9-12) and 143 patients with a mild head injury (GCS 13-15). An operation was performed on 502 patients (69%). Emergency surgery (<24 h) was most frequently performed for patients with an extracerebral mass lesions (subdural hematomas) whereas delayed surgery was most frequently performed for an intracerebral hematoma or contusion. Decompressive craniectomy was performed in a substantial number of patients, either during an emergency procedure (n = 134, 33%) or a delayed procedure (n = 47, 31%). The decompressive procedure was nearly always combined with evacuation of a mass lesion. The size of the decompression was however considered too small in 25% of cases.

CONCLUSION

The results provide a contemporary picture of neurosurgical surgical approaches to the management of head injured patients with an intradural mass lesion and/or signs of raised intracranial pressure in some Neurosurgical Units across the world. The relative benefits of early versus delayed surgery in patients with intraparenchymal lesions and on the indications, technique and benefits of decompressive craniectomy could be topics for future head injury research.

A diagnostic flowchart, including TCD, Xe-CT and angiography, to improve the diagnosis of vasospasm critically affecting cerebral blood flow in patients with subarachnoid haemorrhage, sedated and ventilated

The aim of this study was to prospectively evaluate a clinical protocol including transcranial doppler (TCD), Xenon-CT (Xe-CT) and angiography, for the detection of vasospasm leading to critical reductions of regional cerebral blood flow (rCBF) in both ventilated and sedated SAH patients, i.e. patients in whom clinical evaluation was not possible. Seventy-six patients were prospectively included in a surveillance protocol for daily TCD vasospasm monitoring. When TCD showed a V(mean) above 120 cm/sec in the middle cerebral artery (MCA), patients underwent Xe-CT study. If rCBF in the MCA was reduced to below 20 ml/100 g/min or if there was a reduction in the rCBF with significant asymmetry between the two MCAs, angiography was performed. Conversely, further Xe-CT and angiography were not obtained unless the TCD V(mean) values reached values above 160 cm/sec. In 35 patients, V(mean) attained values above 120 cm/sec, but only in five of them, rCBF was suggestive of vasospasm, and angiography confirmed the diagnosis in four. The protocol suggests that in sedated and ventilated patients, detection of a critical rCBF reduction due to vasospasm is possible to allow for more specific treatment and to reduce undue medical complications.

The role of surgery in traumatic brain injury

PURPOSE OF REVIEW

To identify the surgical indications in the treatment of posttraumatic intracranial hematomas and to evaluate the role of external decompression in severe posttraumatic intracranial hypertension.

RECENT FINDINGS

An evidence-based review resulted recently in the publication of Guidelines for Surgical Management of Traumatic Brain Injury. Unfortunately all published surgical studies are at the level of simple options with no standards. We know that a number of patients harbouring small epidural/subdural hematomas can be managed conservatively when the lesions are less than 10 mm of thickness and with a midline shift of less than 5 mm. With exception of these few cases, the current practice is that a large number of patients with posttraumatic hematomas are operated either within 24 h from injury (with acute subdural hematomas as the prevailing lesion) or later (with parenchymal hematomas as the prevailing lesion). According to a recent European study, about one third of these patients are also decompressed.

SUMMARY

A surgical approach is frequent in posttraumatic intracranial hematomas in spite of a low level of evidence. One of the surgical options either in association with hematoma evacuation or in isolation is the technique of bone flap decompression.

Global cerebral blood flow and CPP after severe head injury: a xenon-CT study

OBJECTIVE

To evaluate the association between global cerebral blood flow and different cerebral perfusion pressure ranges in severe head injury.

DESIGN

A retrospective study

SETTING

Neurosurgical and trauma patients in an intensive care unit in a regional hospital.

PATIENTS AND PARTICIPANTS

Out of a series of 237 consecutive patients with severe head injuries (GCS<or=8), 162 were submitted to ICP monitoring and 89 of them underwent 180 xenon-CT studies and cerebral perfusion pressure (CPP) measurement. The xenon-CT studies did not include any unsalvageable patients nor any mistakenly diagnosed as severe on entry.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Most (95.6%) of xenon-CT studies were obtained with CPP values within the 50-90 mmHg range. Perfusion data were grouped according to CPP values: (1) below 50 mmHg, (2) 50-60 mmHg, (3) 60-70 mmHg, (4) above 70 mmHg. Global cerebral blood flow did not differ among the groups (p=0.49). No differences in physiological variables were found among the CPP groups, except for intracranial pressure, higher in the group with CPP below 50 mmHg, and mean arterial pressure, higher in the CPP above 70 mmHg group (p<0.0001). No differences were found for cerebral metabolic rate of oxygen and lactate.

CONCLUSIONS

There was little correlation between CPP values and global cerebral blood flow levels in our selected patients, probably because pressure autoregulation was preserved. Global metabolism measurements were constant within the groups, suggesting that in patients with controlled physiological variables an interplay between cerebral blood flow and metabolism might be more relevant than the relationship between CPP and cerebral blood flow.

Cerebral blood flow in traumatic contusions is predominantly reduced after an induced acute elevation of cerebral perfusion pressure

OBJECTIVE

To evaluate the response to an acute elevation of cerebral perfusion pressure (CPP) of the regional cerebral blood flow (rCBF) measured in the edematous area of traumatic contusions.

METHODS

rCBF was measured in the intracontusional low-density area, in the pericontusional healthy-appearing brain tissue surrounding the contusion, in a healthy-appearing area in the contralateral hemisphere, in 16 head-injured patients with 16 traumatic contusions larger than 2 cm at baseline, and after 20 minutes of norepinephrine-induced 20-mmHg elevation of CPP levels.

RESULTS

After an induced acute elevation of CPP from baseline values of 65.8 ml/100 g/min (standard deviation, 8.6) to final values of 88.7 ml/100 g/min (standard deviation, 8.9; P < or = 0.0001), we found that rCBF mean levels decreased in the intracontusional low-density area (P = 0.0278), and change in rCBF was inversely associated to the baseline values. After grouping contusions according to the rCBF response to induced acute CPP elevation, rCBF mean values recorded at baseline were significantly lower in lesions with "rCBF improvement" than in those with "rCBF reduction" in the intracontusional low-density area (P = 0.0435).

CONCLUSION

Our findings suggest that CPP elevation induced by norepinephrine is effective in improving contusional rCBF only in selected cases, which are represented by a subset of contusions with critical perfusion, which can be identified by rCBF measurements. Conversely, in contusions with rCBF higher than critical low values, the CPP elevation could probably induce a temporary breakdown of the blood brain barrier, and the norepinephrine leads to a vasoconstriction with a worsening of regional perfusion.

Custom made cranioplasty prostheses in porous hydroxy-apatite using 3D design techniques: 7 years experience in 25 patients

BACKGROUND

None of the materials currently used to reconstruct skull defects is fully satisfactory. Their biological and physical properties are very different to those of natural bone. Solid state, high porosity hydroxy-apatite (HA) seems to be a good support for bone regeneration within the prostheses, enabling integration of the heterologous material with low post-implant infective risk.

MATERIALS AND METHODS

A model of the cranium of each patient was made in epoxy resin by stereolithography. The prosthesis was built on this model using a ceramic sintering process. In each case, an exact copy of the missing bone flap was obtained (curvature, dimensions, margins, irregularities and thickness). The porosity obtained is the same as that of the spongy bone of the skull with interconnected macropores (>150 microm) to promote osteoblast migration into the prosthetic core. In The Neurosurgery Division of Cesena, 26 cranioplasty prostheses have been implanted with this technique in 7 years (from 1998 to 2004). No particular criteria were pre-established, but the main indications for use of ceramic prostheses were complex and/or extended (surface >25 cm(2)) post-surgery craniolacuna and/or previous unsuccessful procedures due to rejection, infection or bone flap reabsorption.

RESULTS

Twenty-five patients were included in this study. A clinical check-up and 3D CT (mean follow-up 30 months, range 12-79) always showed an excellent aesthetic result. No cases of infection, rejection or spontaneous prosthesis fragmentation were found. The surgical procedure was simpler and shorter than for other described procedures.

CONCLUSIONS

Bioceramic porous hydroxy-apatite prosthesis have been demonstrated as a valid alternative to traditional cranioplasty techniques both aesthetically and in terms of absence of infections/rejections. Principal limitations for the use of HA prostheses are the need for stereolithography process, the poor malleability of the material and the high cost.

Regional cerebral blood flow levels as measured by xenon-CT in vascular territorial low-density areas after subarachnoid hemorrhage are not always ischemic

INTRODUCTION

The aim of this study was to assess regional cerebral blood flow (rCBV) in areas of CT hypoattenuation appearing in the postoperative period in patients treated for aneurysmal subarachnoid hemorrhage (SAH) using xenon-enhanced CT scanning (Xe-CT).

METHODS

We analyzed 15 patients (5 male and 10 female; mean age 49.7+/-12.1 years) with SAH on CT performed on admission to hospital and who showed a low-density area within a well-defined vascular territory on CT scans after clipping or coiling of a saccular aneurysm. All zones of hypoattenuation were larger than 1 cm(2) and showed signs of a mass effect suggesting a subacute phase of evolution. Two aneurysms were detected in two patients. Aneurysms were located in the middle cerebral artery (n=7), in the anterior communicating artery (n=6), in the internal carotid artery (n=3), and in the posterior communicating artery (n=1). Treatments were surgical (n=8), endovascular (n=2) or both (n=1). A total of 36 Xe-CT studies were performed and rCBF values were measured in two different regions of interest (ROI): the low-density area, and an area of normal-appearing brain tissue located symmetrically in the contralateral hemisphere.

RESULTS

rCBF levels were significantly lower in the low-density area than in the contralateral normal-appearing area (P<0.01). In the low-density areas, irreversible ischemia (CBF <10 ml/100 g per minute) was present in 11/36 lesions (30.6%), ischemic penumbra (CBF 10-20 ml/100 g per minute) and oligemia (CBF 20-34 ml/100 g per minute) in 8/36 lesions (22.2%), relative hyperemia (CBF 34-55 ml/100 g per minute) in 7/36 lesions (19.4%), and absolute hyperemia (CBF >55 ml/100 g per minute) in 2/36 lesions (5.6%).

CONCLUSION

Our study confirmed that rCBF is reduced in new low-density lesions related to specific vascular territories. However, only about one-third of the lesions showed rCBF levels consistent with irreversible ischemia and in a relatively high proportion of lesions, rCBF levels indicated penumbral, oligemic and hyperemic areas.

Xenon-CT and transcranial Doppler in poor-grade or complicated aneurysmatic subarachnoid hemorrhage patients undergoing aggressive management of intracranial hypertension

OBJECTIVE

To evaluate whether elevated flow velocimetry values are associated with critically reduced cerebral blood flow values in deeply sedated patients with acute aneurysmatic subarachnoid hemorrhage and in whom the detection of clinical vasospasm is not feasible.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Neurosurgical and trauma patients in an intensive care unit in a regional hospital.

PATIENTS AND PARTICIPANTS

Twenty-nine patients in the acute phase following subarachnoid hemorrhage who were sedated and ventilated for elevated intracranial pressure, transcranial Doppler vasospasm, or respiratory failure and were studied with at least a coupled xenon-CT/transcranial Doppler study.

MEASUREMENTS AND RESULTS

Combined measurement and comparison of cerebral blood flow by means of xenon-CT and of mean velocity by means of transcranial Doppler in middle cerebral artery territories. The case mix studied was consistent with patients' predominantly poor grade and with a complicated course. The results suggest that in sedated patients flow velocity and measured cortical mixed cerebral blood flow are not correlated, and, more specifically, that flow velocities values above 120 or 160 cm/s and Lindegaard index above 3 are not associated with an ischemic regional cerebral blood flow. Conversely, as many as 55% of the xenon-CT studies were associated with hyperemia.

CONCLUSIONS

In patients with elevated intracranial pressure, mean middle cerebral artery flow velocity or Lindegaard Index does not help to detect critical cerebral blood flow nor elevated cerebral blood flow.

A systematic review of brain injury epidemiology in Europe

BACKGROUND

The world's literature on traumatic brain injury (TBI) grows annually including new reports on epidemiologic findings from many regions. With the wide variety of reports emphasizing various factors it is useful to compile these findings, hence the objective of this report. Thus, we describe epidemiological factors from European studies largely published in the last 20 years.

METHOD

The Medline was searched for TBI related articles from about 1980 to 2003 including terms such as "epidemiology", "head injury", "brain injury" and others. From the research reports identified, we checked references for additional relevant reports and from those reports we abstracted data on TBI incidence, severity, external cause, gender, mortality, prevalence, cost and related factors.

RESULTS

Twenty three European reports met inclusion criteria and included findings from national studies from Denmark, Sweden, Finland, Portugal, Germany, and from regions within Norway, Sweden, Italy, Switzerland, Spain, Denmark, Ireland, the U.K. and France. An aggregate hospitalized plus fatal TBI incidence rate of about 235 per 100,000 was derived. Prevalence rate data were not reported from any European country. An average mortality rate of about 15 per 100,000 and case fatality rate of about 11 per 100 were derived. The TBI severity ratio of hospitalized patients was about 22:1.5:1 for mild vs. moderate vs. severe cases, respectively. The percentages of TBI from external causes varied considerably and several reports reported an association of alcohol use with TBI. Outcome or disability findings were mixed and inconsistent.

INTERPRETATION

It was difficult to reach a consensus on all epidemiological findings across the 23 published European studies because of critical differences in methods employed across the reports. We highly recommend the development of research guidelines to standardize definitional, case finding, and data reporting parameters to help establish a more precise description and hence utility of the epidemiology of TBI in Europe.

Diagnostic impact of the spectrum of ischemic cerebral blood flow thresholds in sedated subarachnoid hemorrhage patients

OBJECTIVE

Ischemia is the main cause of secondary damage in subarachnoid hemorrhage (SAH). Cerebral blood flow (CBF) measurement is useful to detect critical values. We analyzed the diagnostic impact of CBF ischemic thresholds to predict a new low attenuation area on computed tomography (CT) due to failure of large vessel perfusion.

METHODS

We analyzed 48 xenon CT (Xe-CT) studies from 10 patients with SAH. CBF measurements were obtained by means of Xe-CT and cortical regions of interest (ROls). The ROIs which appeared in a hypoattenuation area were recorded. Cortical CBF was tested for specificity and sensitivity as a predictor of hypoattenuation by means of a receiver operating characteristic curve.

RESULTS

Mean age was 58 (SD +/- 12.4) years. The median Fisher score and Hunt and Hess scale were 2 and 3, respectively. The area under the receiver operating characteristic curve was 0.912 (CI 0.896 to 0.926). The cut-off value for best accuracy was 6 mL/ 100 g/min, with a likelihood ratio of 37.

CONCLUSION

The present study suggests a threshold of 6 mL/100 g/ min as a predictor of a new low attenuation area. However, each clinician should choose the most useful threshold according to pre-test probability and the cost/effectiveness ratio of the applied therapies.

Reperfusion of low attenuation areas complicating subarachnoid hemorrhage

Hypoattenuation areas shown on brain CT scans after subarachnoid hemorrhage (SAH) are believed to be associated with persistent ischemia. The aim of this study was to evaluate regional cerebral blood flow (rCBF) in hypoattenuation areas and its evolution over time by means of Xenon CT (Xe-CT). We enrolled 16 patients with SAH who developed a hypoattenuation area in the middle cerebral artery territory. Patients were studied at time zero (the first Xe-CT), within 24 to 96 hours, and 96 hours after the initial Xe-CT. We analyzed 19 hypoattenuation areas caused by vascular distortion, vasospasm, or post-surgical embolization in 48 Xe-CT studies. Areas of hypoattenuation were divided in 2 groups according to initial rCBF. In the first group (n = 15), rCBF was initially above 6 mL/100 gr/min but only 2 were still ischemic (rCBF < 18 mL/ 100 gr/min) 96 hours after the first Xe-CT, while 7 (58%) were hyperemic. Conversely, in the second group with severe ischemia (rCBF < 6 mL/100 gr/min; n = 4) mean rCBF increased (p = 0.08) but still remained below the ischemic threshold. In severely ischemic lesions, rCBF reperfusion occurs but is probably marginally relevant. Conversely, in lesions not initially severely ischemic, residual CBF gradually improved and frequently became hyperemic. The functional recovery of these zones remains to be evaluated.

The Management of Patients with Intradural Post-Traumatic Mass Lesions: A Multicenter Survey of Current Approaches to Surgical Management in 729 Patients Coordinated by the European Brain Injury Consortium

OBJECTIVE:

Controversy exists about the indications and timing for surgery in head injured patients with an intradural mass lesion. The aim of this study was to survey contemporary approaches to the treatment of head injured patients with an intradural lesion, placing a particular focus on the utilization of decompressive craniectomy.

METHODS:

A prospective international survey was conducted over a 3-month period in 67 centers from 24 countries on the neurosurgical management of head injured patients with an intradural mass lesion and/or radiological signs of raised intracranial pressure. Information was obtained about demographic, clinical, and radiological features; surgical management, and mortality at discharge.

RESULTS:

Over the period of the study, data were collected about 729 patients consecutively admitted to one of the participating centers. The survey included 397 patients with a severe head injury (Glasgow Coma Scale [GCS] 3–8), 155 with a moderate head injury (GCS 9–12) and 143 patients with a mild head injury (GCS 13–15). An operation was performed on 502 patients (69%). Emergency surgery (&lt;24 h) was most frequently performed for patients with an extracerebral mass lesions (subdural hematomas) whereas delayed surgery was most frequently performed for an intracerebral hematoma or contusion. Decompressive craniectomy was performed in a substantial number of patients, either during an emergency procedure (n = 134, 33%) or a delayed procedure (n = 47, 31%). The decompressive procedure was nearly always combined with evacuation of a mass lesion. The size of the decompression was however considered too small in 25% of cases.

CONCLUSION:

The results provide a contemporary picture of neurosurgical surgical approaches to the management of head injured patients with an intradural mass lesion and/or signs of raised intracranial pressure in some Neurosurgical Units across the world. The relative benefits of early versus delayed surgery in patients with intraparenchymal lesions and on the indications, technique and benefits of decompressive craniectomy could be topics for future head injury research.

Factors Associated with Neurological Outcome and Lesion Progression in Traumatic Subarachnoid Hemorrhage Patients

OBJECTIVE:

Traumatic subarachnoid hemorrhage (tSAH) is a frequent finding after closed-head injuries, and its presence is a powerful factor associated with poor outcome. The exact mechanism linking tSAH and an adverse outcome is poorly understood. The aim of this study was to identify the factors that may predict outcomes and changes in the computed tomographic (CT) scans of lesions in a selected population of tSAH patients.

METHODS:

We evaluated 141 patients admitted consecutively from January 1, 1997, to January 31, 1999, with a CT diagnosis of tSAH. The admission and “worst” CT scans were recorded. CT scan changes were reported as “significant CT progression” (changes in the Marshall classification) or “any CT progression.” The amount of subarachnoid blood was recorded using a modified Fisher classification. Outcome was assessed at 6 months after injury with the Glasgow Outcome Scale.

RESULTS:

Twenty-eight patients (19.9%) had an unfavorable Glasgow Outcome Scale outcome. In the univariate analysis, prognosis was significantly related to age, admission Glasgow Coma Scale score, Marshall CT classification score at admission and on the worst CT scan, amount of tSAH, and volume of the associated brain contusions. From multivariate analysis, the only factors independently related to outcome were the Glasgow Coma Scale score (P &lt; 0.01) and size of the tSAH at admission (P &lt; 0.001). Thirty-four patients (24.1%) had significant CT lesion progression, and 66 patients (46.8%) had some lesion progression. Patients having significant progression of the lesion had a higher risk of an unfavorable outcome (32 versus 10%; P = 0.004). Unadjusted factors predicting CT progression were the Glasgow Coma Scale score at admission, the Marshall classification at admission, the amount of subarachnoid blood, and the presence or volume of associated brain contusions at admission. Independent factors associated with significant CT progression were the amount of tSAH (P &lt; 0.001) and the presence or volume of brain contusions at admission (P &lt; 0.001).

CONCLUSION:

The outcome of patients with tSAH at admission is related in a logistic regression analysis to the admission Glasgow Coma Scale score and to the amount of subarachnoid blood. These patients also have a significant risk of CT progression. The amount of subarachnoid blood and the presence of associated parenchymal damage are powerful independent factors associated with CT progression, thus linking poor outcomes and CT changes.

Cerebral blood flow mapping in two different subtypes of intraparenchymal hemorrhagic traumatic lesions

The pathogenesis and the viability of edematous tissue may be different in traumatic hematomas and traumatic contusions. We tested the hypothesis that mapping of regional Cerebral Blood Flow (rCBF) was different in these two subtypes of traumatic intraparenchymal lesions. We evaluated rCBF by means of Xenon-enhanced computerized tomography (Xe-CT) in 59 traumatic intracerebral lesions from 43 patients with severe head injury. One-hundred-nine intracerebral lesions/Xe-CT CBF measurements were obtained. The rCBF was measured in the hemorrhagic core, in the intralesional oedematous low density area and in a 1 cm rim of apparently normal perilesional parenchyma of both lesion subtypes. Not statistically significant lower rCBF levels were found in the edematous area of traumatic contusions. In traumatic hematomas rCBF levels were lower in the core than in the low density area, suggesting that rCBF in edematous area is marginally involved in the initial traumatic injury and that edema is probably influenced by the persistence of the hemorrhagic core. Conversely, in the traumatic contusions a difference in rCBF values was found between core, low density area and perilesional area, indicating that rCBF of the low density area is related to a concentrical distribution of the initial injury.

Cerebral blood flow in mean cerebral artery low density areas is not always ischemic in patients with aneurysmal subarachnoid hemorrhage--relationship with neurological outcome

Aneurysmal subarachnoid hemorrhage (SAH) can be complicated by reduction of regional cerebral blood flow (rCBF) from large conductance vessels leading to focal edema appearing as an area of hypoattenuation on CT. In this study we included 29 patients with SAH due to aneurysmal rupture, having 36 CT low density areas within the middle cerebral artery territory in whom a total of 56 Xenon-CT (Xe-CT) studies were performed. Collectively, we evaluated 70 hypoattenuated areas. rCBF levels were measured in two different regions of interest drawn manually on the CT scan, one in the low density area and the other in a corresponding contralateral area of normal-appearing brain tissue. In the low density area (22.6 +/- 22.7 ml/100 gr/min) rCBF levels were significantly lower than in the contralateral area (32.8 +/- 17.1 7 ml/100 gr/min) (p = 0.0007). In the injured areas deep ischemia (CBF < 6 ml/ 100 g/min) was present in only 25.7% of Xe-CT studies, suggesting that hypodense areas are not always ischemic, whereas in 43.7% of the lesions/Xe-CT studies we found hyperemic values. Patients with a better outcome had hyperemic lesions, suggesting brain tissue recovery in injured areas.

Estimated cerebral respiratory quotient and arteriovenous differences of CO2 in the ultra early detection of global ischemia in severe head injury

The specificity of jugular bulb saturation (SjO2) and arteriovenous oxygen difference (AVDO2) to detect global cerebral ischemia remains controversial. An absolute increase in the arteriovenous difference of carbon dioxide tension (AVDpCO2) and, more specifically, the estimated respiratory quotient (eRQ = AVDpCO2/AVDO2) may indicate anaerobic CO2 production. We compared these variables with SjO2 to predict global cerebral ischemia. We selected 36 patients from a cohort of 69 consecutive patients suffering from severe traumatic brain injury. All patients had jugular bulb sampling within 6 hours after injury. Brain death at 48 hours was used as a surrogate index of irreversible ischemia to build a receiver operating characteristics (ROC) curve analysis. The mean (+/- standard deviation) eRQ in the 13 patients who died early (3.7 +/- 3.2 mmHg/ml/dl) was higher than the survivors (1.78 +/- 0.45 mmHg/ml/dl, P = 0.03). There was no differences in SjO2 between groups. The area under the ROC curves for eRQ, but not that of AVDpCO2, was greater (P = 0.04) than that of SjO2. The eRQ, more than AVDpCO2, appears to be a potentially more informative index of global cerebral ischemia than SjO2.