Zygapophysial joint pain in selected patients

The zygapophysial joints (z-joints), together with the intervertebral disc, form a functional spine unit. The joints are typical synovial joints with an innervation from two medial branches of the dorsal rami. The joint capsule and the surrounding structures have an extensive nerve supply. The stretching of the capsule and loads being transmitted through the joint can cause pain. The importance of the z-joints as a pain generator is often underestimated because the prevalence of z-joint pain (10%-80%) is difficult to specify. Z-joint pain is a somatic referred pain. Morning stiffness and pain when moving from a sitting to a standing position are typical. No historic or physical examination variables exist to identify z-joint pain. Also, radiologic findings do not have a diagnostic value for pain from z-joints. The method with the best acceptance for diagnosing z-joint pain is controlled medial branch blocks (MBBs). They are the most validated of all spinal interventions, although false-positive and false-negative results exist and the degree of pain relief after MBBs remains contentious. The prevalence of z-joint pain increases with age, and it often comes along with other pain sources. Degenerative changes are commonly found. Z-joints are often affected by osteoarthritis and inflammatory processes. Often additional factors including synovial cysts, spondylolisthesis, spinal canal stenosis, and injuries are present. The only truly validated treatment is medial branch neurotomy. The available technique vindicates the use of radiofrequency neurotomy provided that the correct technique is used and patients are selected rigorously using controlled blocks.

Swine model in transplant research: Review of anaesthesia and perioperative management

Pigs are one of most common animal species to be used in biomedical models due to their many anatomical visceral similarities with humans, particularly with regards to transplantation. Despite this use, in many of the researches in which pigs are selected for transplantation, the anaesthesia used is an adaptation of human anaesthesia and presents some limitations such as a reduced analgesia a limited control in perioperative period. In this review we show some of the most important conditions in the preanaesthetic management and of swine as well as we review of anaesthetic protocols for the most common types of swine model of transplantation.

Sugammadex: Role in current anaesthetic practice and its safety benefits for patients

Sugammadex has revolutionized anaesthetic management of reversal of neuromuscular block (NMB) by way of its unique mechanism of action encapsulating the amino steroid neuromuscular blocking drugs rocuronium and vecuronium. The cholinesterase inhibitors have significant pharmacological and clinical limitations whereas sugammadex allows predictable, safe and rapid reversal from any depth of blockade. The financial cost of sugammadex is significant. Many hospitals in the United Kingdom use clinical guidelines to direct best use of sugammadex in their institutions. Auditing the use of sugammadex provides useful information on which patients are benefiting from sugammadex. The clinical benefits of sugammadex are well understood. No patient should now be subjected to the danger of post-operative residual curarization. Versatility in the ability to reverse NMB has brought opportunities to the anaesthetist in the management of rapid sequence induction using high dose rocuronium with the knowledge that safe reversal of NMB is now possible in the unlikely event of a “can’t intubate can’t ventilate” situation. Do we still need suxamethonium to be available? The nature of surgery continues to evolve with ever-increasing enthusiasm for minimally invasive laparoscopic techniques. There is evidence to support using a deeper level of NMB to improve the working space and operating conditions in laparoscopic surgery. It is now possible to maintain a deep level of NMB right up until the end of surgery with no concerns about the ability to effect safe reversal of NMB. Vigilance about the possibility of allergic sensitivity to sugammadex needs to be maintained. The increased usage of rocuronium has the potential for rocuronium-induced anaphylaxis. Conversely, there is a potential role for sugammadex in the treatment of rocuronium anaphylaxis. Clinicians who have used sugammadex are struck with the quality of recovery seen in their patients. It is important that the economic implications of the use of sugammadex are fully understood. This article considers the current role of sugammadex in clinical practice outside of routine reversal of NMB and discusses how the addition of sugammadex to the anaesthetic armamentarium brings safety benefits for patients.

Update in perioperative anesthetic management of pheochromocytoma

Pheochromocytoma is a tumor that originates from either chromaffincells in adrenal medulla or in other paraganglia tissues of the sympathetic nervous system. The perioperative management is quite challenging especially in view of hemodynamic fluctuations. Pheochromocytoma is challenging in view of the impact of excessive and depleted catecholamines in the perioperative period. It requires a through preoperative evaluation and optimization with meticulous intraoperative management. The postoperative period requires vigilance to prevent any untoward complication. In this review we review these concepts based on recent evidence for an optimal outcome.

Perioperative hypothermia: Causes, consequences and treatment

Perioperative hypothermia, core temperature below 36.0 °C, transpires due to disruption of thermoregulation by anesthesia coupled with cold exposure to procedural surroundings and cleansing agents. Although most publications have focused on thermoregulation disruption with general anesthesia, neuraxial anesthesia may also cause significant hypothermia. The clinical consequences of perioperative hypothermia are multiple and include patient discomfort, shivering, platelet dysfunction, coagulopathy, and increased vasoconstriction associated with a higher risk of wound infection. Furthermore, postoperative cardiac events occur at a higher rate; although it is unclear whether this is due to increased oxygen consumption or norepinephrine levels. Hypothermia may also affect pharmacokinetics and prolong postoperative recovery times and hospital length of stay. In order to combat perioperative hypothermia, many prevention strategies have been examined. Active and passive cutaneous warming are likely the most common and aim to both warm and prevent heat loss; many consider active warming a standard of care for surgeries over one hour. Intravenous nutrients have also been examined to boost metabolic heat production. Additionally, pharmacologic agents that induce vasoconstriction have been studied with the goal of minimizing heat loss. Despite these multiple strategies for prevention and treatment, hypothermia continues to be a problem and a common consequence of the perioperative period. This literature review presents the most recent evidence on the disruption of temperature regulation by anesthesia and perioperative environment, the consequences of hypothermia, and the methods for hypothermia prevention and treatment.

Pharmacokinetics and pharmacodynamics of lignocaine: A review

Lignocaine is an essential drug on World Health Organisation essential drug list, considered efficacious, safe and cost-effective for any health-care system. Despite its ubiquitous use in medicine and surgery, there are few detailed reviews of its pharmacokinetics and pharmacodynamics. Being an amide-type local anesthetic and Class 1b antiarrhythmic, lignocaine is most frequently used clinically for its anesthetic and antiarrhythmic benefits. However, lignocaine has important antinociceptive, immuno-modulating, and anti-inflammatory properties. Information pertaining to the pharmacokinetics and pharmacodynamics of lignocaine was examined by performing a literature search of PubMed, Embase and MEDLINE (via Ovid), pharmacology textbooks and online sources. We present a focused synopsis of lignocaine’s pharmacological composition, indications for use and mechanisms of action, focusing on its anti-inflammatory, immuno-modulating and analgesia effects. In addition we review the dosing regimes and infusion kinetics of lignocaine in the clinical setting. Finally, we review the evidence for ligocaine’s modulation of the inflammatory response during major surgery and its specific effects on cancer recurrence. These indirect effects of local anesthetics in tumor development may stem from the reduction of neuroendocrine responses to the stress response elicited by major surgery and tissue damage, enhanced preservation of immune-competence, in addition to opioid-sparing effects of modulating tumor growth.

Anesthesia for bronchoscopic amniotic membrane grafting to treat non-healing bronchial dehiscence

Airway complications after lung transplantation remain a significant cause of morbidity and mortality. Many of these occur at the anastomotic sites, which are susceptible due to poor collateral circulation. Of the possible complications, bronchial dehiscence is particularly formidable. These cases have been successfully treated bronchoscopically with metallic stents, which likely promote healing through granulation tissue formation. However, limited options exist in cases where the dehiscence fails to heal following stent placement. Here, we present the case report of a 65-year-old male who developed bronchial dehiscence status post bilateral lung transplantation for idiopathic pulmonary fibrosis that failed to heal with simple stent placement. Eventually, the patient underwent amniotic membrane grafting with stenting as a novel therapy for non-healing bronchial dehiscence, for which we describe the anesthetic management. His anesthetic plan included inhalational induction with sevoflurane, propofol infusion for total intravenous anesthesia, rocuronium for muscle relaxation, and closed-circuit assisted ventilation. His existing tracheostomy was used as the airway for oxygenation and induction. In summary, our anesthetic plan for the lung transplant patient was effective; future amniotic membrane grafting for bronchial dehiscence through bronchoscopy may follow a similar technique. Ultimately, the choice of anesthesia in this patient population requires judicious consideration of the requirements of the procedure as well as the pathophysiology of the transplanted lung.

Critical importance of tracheal tube cuff pressure management

The ideal range for tracheal tube cuff pressures is usually taken to be between 20 to 30 cm H₂O. This is easily measured with a cuff pressure manometer and should be measured in each instance. The importance of tracheal tube cuff pressures is highlighted by the spectrum of airway complications that can occur with incorrect cuff pressures. High cuff pressures can result in complications ranging from sore throat and hoarseness to tracheal stenosis, necrosis, and even rupture. In such cases, the postulated causative factor is diminished blood flow to tracheal mucosa due to excessive cuff pressure on the tracheal wall. This hypothesized ischemic injury then produces healing fibrosis months or even years later. On the other hand, cuff pressures that are too low place the patient at risk for aspiration of gastric contents and consequently, aspiration pneumonitis and pneumonia. This is why the authors recommend that cuff pressures be measured following all intubations.

Bradycardia and hypotension during pediatric scoliosis surgery-hypovolemia or spinal shock?

We present the case of a 13-year-old boy undergoing scoliosis repair utilizing skull-femoral traction who developed sudden, sustained bradycardia and hypotension during scoliosis repair, associated with loss of somatosensory evoked potentials and motor evoked potentials to all four limbs. A diagnosis of spinal shock and hypovolemia was made after ruling out primary cardiac causes, sepsis, anaphylaxis and intra-spinal pedicle screw placement. Acute complications of surgical scoliosis repair are reviewed along with anatomy of the sympathetic nervous system. In this case spinal shock may have been due to hypovolemia as well as spinal cord manipulation during T12 vertebral column resection that was needed to effect scoliosis correction. Treatment included volume expansion and inotropic support. Anesthesiologists caring for these patients should be mindful of the possibility of spinal shock during correction of severe scoliosis, particularly when vertebral column resection is undertaken.

Translating the expression of pain in the face of uncertainty: The importance of human pain experiments for applied and clinical science

This brief commentary attempts to provide a concise synthesis of social psychology experiments that inform an interpretation of clinical pain. From a social perspective the expression of pain is a complex phenomenon that is greater than the patient’s physiology. Numerous experiments show that pain is modulated by social and contextual factors. These experiments point to the role of the listener as a social agent that can modulate the patient’s expression. Within the clinical setting the patient’s pain experience can be understood as the uncertainty of physical damage and their expression as an attempt to reduce that uncertainty. How successfully this occurs is in part dependent on the empathetic reception of the provider. Chronic pain is a state that is challenging to effectively model in humans but may persist in patients due to an inability to receive effective empathetic reception at the critical time of need (at or near onset). Rather than focusing on pain’s alleviation future avenues of pain interventions may do well by turning attention to the most effective ways to impart a message that the patient will be “okay” in a genuinely empathetic manner.

Transthoracic echocardiography assists appropriate pulmonary artery catheter placement: An observational study

AIM: To investigate the utility of transthoracic echocardiography in confirming appropriate pulmonary artery catheter (PAC) placement.

METHODS: Three commonly used transthoracic echocardiography (TTE) views were used to confirm PAC position in 103 patients undergoing elective cardiac surgery - the parasternal short axis right ventricular inflow-outflow view; the subcostal short axis right ventricular inflow-outflow view; and the parasternal short axis ascending aortic view. All PACs were inserted by the managing anesthesiologist under pressure waveform guidance alone, who was blinded to all sonographic information. A sonographer blinded to all pressure waveform information confirmed visualisation of an “empty” PA before PAC insertion, and visualisation of the PAC balloon in the main PA (MPA) or right PA (RPA) after attempts at placement were complete. Agreement, sensitivity and specificity of TTE in confirming appropriate PAC placement was compared against pressure waveform guidance as the “gold standard”. The successful view used was compared against patients’ anthropomorphic indices, presence of lung hyperinflation, and insertion of PAC during positive pressure ventilation. Agreement between TTE and pressure waveform guidance was analysed using Cohen’s Kappa statistic. The relative proportion of total RPA seen by subcostal vs parasternal TTE views was also compared with a further 20 patients’ computed tomography (CT) pulmonary angiograms (CTPA), to determine efficacy in detection of distal RPA PAC placement.

RESULTS: Appropriate positioning of the PAC balloon, and its to-and-fro movement consistent with a non-wedged state, within the MPA or RPA was confirmed by TTE in 98 of the 103 patients [sensitivity 95% (95%CI: 89%-98%)], and absence of the PAC balloon before insertion correctly established in 100 patients [specificity 97% (92%-99%)]. This was in very good agreement with pressure waveform guidance [Cohen’s Kappa 0.92, (0.87-0.98)]. The subcostal view was the best view to visualise the PAC tip when it was placed in the right pulmonary artery (OR 70, P < 0.0001), was more successful in patients with COAD (OR 9.5, P = 0.001), and visualized 61% (vs 44% by parasternal views, P < 0.001) of mean RPA lengths compared with CTPA; however the parasternal views were more successful in patients with higher body mass indexs (OR 0.78 for success with subcostal views, P < 0.001). There was a trend towards insertion during intermittent positive pressure ventilation favoring visualisation by subcostal views (OR 3.9, P = 0.08). The subcostal view visualized a greater length of the RPA than parasternal views (3.9 cm vs 2.9 cm, P < 0.0001). PACs were more often placed in the MPA than RPA (80 vs 18 patients). Three patient’s pulmonary arteries were not visible by any TTE view; in a further 2 patients, despite pre-insertion visualisation of their pulmonary arteries, the PAC balloon was not visible by any view with TTE where correct placement by pressure waveform was unequivocal.

CONCLUSION: TTE can assist appropriate PAC placement by visualization of an unwedged PAC balloon in the PA.

Anesthesia and acupuncture

Using acupuncture instead of anesthetics to induce analgesia was performed in China many years ago in surgical anesthetization. Although many medical units in China’s cities and rural areas are applying these techniques in operations, it should be pointed out that acupuncture anesthesia is still in the process of development and is of next to no practical and even less scientific value in the western world. However, acupuncture-assisted anesthesia can be useful also in countries other than China.

Human factors in anaesthetic crisis

This paper discusses some of the key aspects of human factors in anaesthesia for the improvement of patient safety. Medical errors have emerged as a serious issue in healthcare delivery. There has been new interest in human factors as a means of reducing these errors. Human factors are important contributors to critical incidents and crises in anaesthesia. It has been shown that the prevalence of human factors in anaesthesia can be as high as 83%. Cognitive thinking process and biases involved are important in understanding human factors. Errors of cognition linked with human factors lead to anaesthetic errors and crisis. Multiple errors in the cognitive thinking process, known as “Cognitive dispositions to respond” have been identified leading to errors. These errors classified into latent or active can be easily identified in the clinical vignettes of serious medical errors. Application of the knowledge on human factors and use of cognitive de-biasing strategies can avoid human errors. These strategies could involve use of checklists, strategies to cope with stress and fatigue and the use of standard operating procedures. A safety culture and health care model designed to promote patient safety can compliment this further. Incorporation of these strategies strengthens the defence layers against the “Swiss Cheese” models, which exist in the health care industry.

Intrathecal morphine for postoperative analgesia: Current trends

The practice of anesthesiology has always been governed by evidence-based medicine. The quick turnover rate of patients in the operating room and patient safety and satisfaction, have also further changed the way we practice anesthesia. The use of intrathecal (IT) opiates as an effective form of postoperative pain relief has been established for many years. Morphine was the first opioid used by IT route. In clinical practice, morphine is regarded as the gold standard, or benchmark, of analgesics used to relieve intense pain. Perhaps for this reason, IT morphine has been used for over 100 years for pain relief. IT morphine is one of the easiest, cost-effective and reliable techniques for postoperative analgesia and technical failures are rare. And yet there is no consensus amongst anesthesiologists regarding the dose of IT morphine. Like all other methods of pain relief, IT morphine also has some side effects and some of them are serious though not very common. This review article looks into some of the key aspects of the use of IT morphine for post-operative analgesia and various doses for different procedures are discussed. This article also describes the side effects of IT morphine and how to treat and prevent them.

Phantom limb pain: A review of evidence-based treatment options

Phantom limb pain (PLP) is not uncommon after amputation. PLP is described as a painful sensation perceived in the missing limb. Despite of its complicated pathophysiology, high prevalence of PLP has been associated with poor health-related quality of life, low daily activity and short walking distances. A prompt and effective management of PLP is essential in caring for the amputee population. Current treatments including physical therapy, psychotherapy, medications, and interventions have been used with limited success. In this review, we provided an updated and evidence-based review of treatment options for PLP.

Lumbar radiculopathy and its neurobiological basis

Lumbar radiculopathy, a group of diseases in which the dorsal root ganglia (DRG) or dorsal roots are adversely affected by herniated discs or spinal stenosis, are clinically characterized by spontaneous and evoked types of pain. The pain is underpinned by various distinct pathophysiological mechanisms in the peripheral and central nervous systems. However, the diagnosis of lumbar radiculopathy is still unsatisfactory, because the association of the pain with the neurobiological basis of radiculopathy is largely unknown. Several animal models used to explore the underlying neurobiological basis of lumbar radiculopathy could be classified as mechanical, chemical, or both based on the component of injury. Mechanical injury elevates the intraneural pressure, reduces blood flow, and eventually establishes ischemia in the dorsal root and the DRG. Ischemia may induce ischemic pain and cause nerve damage or death, and the subsequent nerve damage or death may induce neuropathic pain. Chemical injury predominately induces inflammation surrounding the dorsal roots or DRG and consequent inflammatory mediators cause inflammatory pain. Furthermore, DRG neurons sensitized by inflammatory mediators are hypersensitive to innocuous mechanical force (stretch or compression) and responsible for mechanical allodynia in radiculopathy. As well, central sensitization in the spinal cord may play an important role in pain generation in lumbar radiculopathy. Increasing knowledge of pain-generating mechanisms and their translation into clinical symptoms and signs might allow for dissecting the mechanisms that operate in each patient. With precise clinical phenotypic characterization of lumbar radiculopathy and its connection to a specific underlying mechanism, we should be able to design optimal treatments for individuals. This review discusses the present knowledge of lumbar radiculopathy and proposes a novel mechanism-based classification.

Anesthesia for ambulatory surgery in a child with hyposensitivity to pain

Congenital hyposensitivity to pain is a condition with predisposition to injury. In these patients, knowledge regarding anesthetic requirements and complications derives from individual case reports, or small case series. Different categories have been described. In patients with hyposensitivity to pain, preventing and treating anxiety as well as insuring immobilization, avoidance of triggering of autonomic reflexes, and sedation are integral aspects for a safe and adequate anesthetic management.

Paroxetine vs pregabalin for the management of neuropathic pain in multiple sclerosis

AIM: To compare the effectiveness and tolerability of paroxetine vs pregabalin for the management of multiple sclerosis (MS)-induced neuropathic pain (NPP).

METHODS: A randomized, flexible-dose open-label 8-wk study involving 21 relapsing-remitting MS patients with MS-induced NPP was conducted to evaluate the effectiveness and tolerability of pregabalin versus paroxetine for pain management. The trial included a 3-wk dose titration phase followed by a 5-wk stable dose phase. Primary outcome measures included daily patient-reported pain intensity as measured using a 100 mm visual analogue scale (VAS_pain) and daily impact of pain on daily activities (VAS_impact). Hierarchical regression modeling was conducted on each outcome to determine if within person VAS trajectory for pain and impact differed across study groups, during 56 d follow-up.

RESULTS: Attrition rates were significantly greater (P < 0.001) in the paroxetine versus pregabalin study group (70% vs 18.2%, respectively). Average study duration between study groups also significantly differed (P < 0.001). Paroxetine participants completed an average of 27.3 d of treatment vs 49.5 d in the pregabalin group, with the majority of patients withdrawing due to adverse events. Due to the high attrition rates in the paroxetine study arm, the investigators stopped the study prior to achieving complete recruitment. As such, no significant differences between pregabalin and paroxetine study arms were noted for the primary outcome measures (VAS_pain, VAS_impact). Comparative assessment of baseline patient characteristics also revealed no significant differences between the study arms.

CONCLUSION: High attrition rates associated with paroxetine use suggest that it be used with caution for MS-induced NPP. Efficacy outcomes could not be assessed due to attrition.

Endoscopic removal of a self-expanding metallic airway stent: A case report

Self-expanding metallic stents are sometimes placed for the management of obstructing airway lesions or conditions such as airway wall malacia or tracheal stenosis. However, endoscopic removal of these devices from the airway can pose extreme challenges for both clinical airway management as well as for the administration of general anesthesia. We report on a 61-year-old man with a complex cardiac history presenting for endoscopic stent removal necessitated by the formation of extensive granulation tissue. Comorbidities included a history of myocardial infarction, an ischemic cardiomyopathy with severe left heart failure (ejection fraction of 25%), mild right heart failure, 2+ tricuspid regurgitation status post tricuspid valve repair, and atrial fibrillation. An automatic external (wearable) cardiac defibrillator (Zoll Life Vest) was also in place. Induction of anesthesia was carried out using etomidate, with maintenance of anesthesia carried out with a propofol infusion (total intravenous anesthesia). Rocuronium was used for neuromuscular blockade. A size 4 iGel supraglottic airway and, later, rigid bronchoscopy formed the basis for airway management. Stable conditions were met through the 2-h procedure, and the patient recovered uneventfully. Our successful experience in this case leads us to propose further use of a supraglottic airway in conjunction with total intravenous anesthesia for these procedures.

Comparison of flow rate accuracy and consistency between the on-Q, baxter, and ambu pain infusion devices

AIM: Providing analgesia via peripheral nerve catheters attached to an infusion pump is an effective pain management option in children.

METHODS: Portable infusion pumps are being used with increased frequency in pediatric patients. Because these pumps are infusing potentially toxic doses of medications, the accuracy and consistency of these devices becomes very important in this patient population. This study is a comparison of the actual delivery volume of local anesthetic of three elastomeric infusion devices approved for patient use in the ambulatory setting. Three brands of disposable elastomeric infusion devices were used (Five On-Q, Five Baxter, and Five Ambu pumps). Each was filled with 200 mL of Ropivicaine 0.1% and connected to a single, end hole infusion catheter and set to infuse at 12 mL/h. The devices were run simultaneously. The fluid delivered was measured every hour with a graduated column over a tenhour period. The ambient temperature was also recorded.

RESULTS: There were statistically significant differences in the output from each elastomeric device over the 10 h infusion period when compared to the nominal rate of 12 mL/h. The output from the Ambu and Baxter pumps was less than that set on the regulator, while the output from the On-Q pump was greater than that set on the regulator. The results remained statistically significant after adjusting the nominal rate to correct for differences in temperature. The Ambu infusion device was the most consistent, while the Baxter infusion device was the most accurate. This emphasizes the importance of health care providers understanding the infusion profile of the pump being used for continuous peripheral nerve block, as these alterations in flow could result in inadequate analgesia, early reservoir exhaustion, excessive muscle weakness or potential toxicity, especially when used in pediatric patients.

CONCLUSION: This investigation demonstrates that three modern elastomeric infusion pumps have significantly different output than the nominal rate set on the regulator.

Complex regional pain syndrome: From diagnosis to rehabilitation

Complex regional pain syndrome (CRPS) is a debilitating pathology characterised by intense chronic pain associated with vasomotor, sensory and motor dysfunction of the affected limb. Although the pathophysiology of CRPS is not fully understood, it is recognised that inflammatory processes and autonomic dysfunction are involved. These processes are associated with peripheral and central sensitisation as well as changes in brain structure and function, and are reflected in the clinical presentation of CRPS. CRPS management requires an interdisciplinary team and requires the therapeutic approach to be individualised. With regard to pharmacological treatment, bisphosphonates, corticosteroids, ketamine and anticonvulsants have been demonstrated to be effective for CRPS management. Psychotherapy, including cognitive-behavioural therapy, has produced promising results but more studies are needed to confirm its efficacy. Among rehabilitation interventions, there is evidence of the efficacy of physiotherapy and occupational therapy in diminishing CRPS symptoms and achieving a higher level of functioning. In this regard, the rehabilitation modality that seems the most promising according to the actual literature is graded motor imagery, which can help to reverse the maladaptive neuroplasticity occurring in CRPS.

Molecular mechanism of inflammatory pain

Chronic inflammatory pain resulting from arthritis, nerve injury and tumor growth is a serious public health issue. One of the major challenges in chronic inflammatory pain research is to develop new pharmacologic treatments with long-term efficacy and few side effects. The mediators released from inflamed sites induce complex changes in peripheral and central processing by directly acting on transducer receptors located on primary sensory neurons to transmit pain signals or indirectly modulating pain signals by activating receptors coupled with G-proteins and second messengers. High local proton concentration (acidosis) is thought to be a decisive factor in inflammatory pain and other mediators such as prostaglandin, bradykinin, and serotonin enhance proton-induced pain. Proton-sensing ion channels [transient receptor potential V1 (TRPV1) and the acid-sensing ion channel (ASIC) family] are major receptors for direct excitation of nociceptive sensory neurons in response to acidosis or inflammation. G-protein-coupled receptors activated by prostaglandin, bradykinin, serotonin, and proton modulate functions of TRPV1, ASICs or other ion channels, thus leading to inflammation- or acidosis-linked hyperalgesia. Although detailed mechanisms remain unsolved, clearly different types of pain or hyperalgesia could be due to complex interactions between a distinct subset of inflammatory mediator receptors expressed in a subset of nociceptors. This review describes new directions for the development of novel therapeutic treatments in pain.

Perioperative care and cancer recurrence: Is there a connection?

Cancer is the second most common cause of death in the United States. Metastatic disease is a more important cause of cancer-related death relative to primary tumor progression. Surgical excision is the primary treatment for most malignant tumors. However, surgery itself can inhibit important host defenses and promote the development of metastases. An altered balance between the metastatic potential of the tumor and the anti-metastatic host defenses, including cell-mediated immunity and natural killer cell function, is a plausible mechanism of increased cancer metastasis. This article reviews the increasingly recognized concept of anesthetic technique along with perioperative factors and their potential to affect long-term outcome after cancer surgery. The potential effect of intravenous anesthetics, volatile agents, local anesthetic drugs, opiates, and non-steroidal anti-inflammatory drugs are reviewed along with recent literature and ongoing clinical trials in this area. Regional anesthesia is increasingly emerging as a safer option with less cancer recurrence potential as compared to general anesthesia. Blood transfusion, pain, stress, use of beta-blockers, and hypothermia are other potentially important perioperative factors to consider.

Acute coagulopathy of trauma: Mechanism, monitoring, management

Coagulopathy is a well-known consequence of trauma and is the most common cause of mortality in the young. However, its cause and management is still controversial. A new concept in the understanding of coagulopathy in trauma is the occurrence of Acute coagulopathy of trauma (ACoT). ACoT is associated with hypo perfusion and tissue trauma as seen in massive injury. The incidence of coagulopathy increases with injury scores and is associated with higher number of ventilator days, higher morbidity and mortality. The process of coagulation is better described by the cell based model with a central role for platelets rather than the older plasma based model. This shift in our understanding supports the theory that ACoT results from the endothelial release of thrombomodulin and activated protein C in the presence of hypoperfusion. This in turn leads on to a hyperfibrinolytic and hypocoagulable state. Viscoelastic hemostatic assays are replacing the older tests like prothrombin time in the assessment of coagulopathy. These tests are accurate, determine the need for transfusion and can be performed at the point of care. Damage control resuscitation includes newer concepts like permissive hypotension, increased use of plasma as a part of massive transfusion protocols and damage control surgery.

Opioid misuse in Canada and critical appraisal of aberrant behavior screening tools

The incidence of prescription opioid misuse in Canada is increasing. Initiatives for safe prescribing practices for opioid medications include risk assessment for current and future opioid misuse. A clinical screening tool that can be universally applied to all patient populations is currently not available. Our objective was to provide a brief narrative review on opioid misuse from a Canadian perspective as well as a critical appraisal of the available clinical screening tools for detecting aberrant behaviors associated with opioid misuse. The Drug Abuse Screening Test, Addiction Behaviors Checklist, Diagnosis, Intractability, Risk and Efficacy Inventory, Pain Assessment and Documentation Tool, Prescription Drug Use Questionnaire, Prescription Opioid therapy Questionnaire, Screener and Opioid Assessment for Patients with Pain (SOAPP), Revised SOAPP, Pain Medication Questionnaire, Opioid Risk Tool and Current Opioid Misuse Measure were included in the following review. Overall, a wide variability in quality, sensitivity and specificity was observed between screening tools. There is an overall lack of applicability to diverse patient populations as the majority of screening tools have been validated in pain clinic populations only. To conclude, there is a great need for a validated and convenient aberrant behaviors risk assessment tool that can be applied to a diverse patient population in a clinical setting.