Adverse effects of nitrous oxide

Factors affecting the topography of nitrous oxide-induced neurological complications

BACKGROUND

The factors underlying the topography of nitrous oxide (N2O)-induced neurological complications are unknown.

METHODS

We included all consecutive patients admitted to the university hospital of Marseille for N2O-induced neurological complications in a prospective observational study. Patients underwent neurological examination, spinal cord magnetic resonance imaging, and nerve conduction studies within the first 4 weeks after admission.

RESULTS

In total, 61 patients were included: 45% with myeloneuropathy, 34% with isolated myelopathy, and 21% with isolated neuropathy. On multivariable analysis, the odds of myelopathy were associated with the amount of weekly N2O consumption (~600 g cylinder per week, odds ratio [OR] = 1.11, 95% confidence interval [CI] = 1.001-1.24). The extent of the myelopathy (number of vertebral segments) was correlated with the number of ~600-g cylinders consumed weekly (ρ = 0.40, p < 0.005). The odds of neuropathy were associated with the duration of consumption (per month; OR = 1.29, 95% CI = 1.05-1.58). Mean lower-limb motor nerve amplitude was correlated with the duration of consumption (in months; ρ = -0.34, p < 0.05).

CONCLUSIONS

The odds of myelopathy increased with the amount of N2O consumption, and the odds of neuropathy increased with the duration of N2O exposure, which suggests distinct pathophysiological mechanisms underlying these two neurological complications.

A call for immediate climate action in anesthesiology: routine use of minimal or metabolic fresh gas flow reduces our ecological footprint

PURPOSE

Climate change is a global threat, and inhalational anesthetics contribute to global warming by altering the photophysical properties of the atmosphere. On a global perspective, there is a fundamental need to reduce perioperative morbidity and mortality and to provide safe anesthesia. Thus, inhalational anesthetics will remain a significant source of emissions in the foreseeable future. It is, therefore, necessary to develop and implement strategies to minimize the consumption of inhalational anesthetics to reduce the ecological footprint of inhalational anesthesia.

SOURCE

We have integrated recent findings concerning climate change, characteristics of established inhalational anesthetics, complex simulative calculations, and clinical expertise to propose a practical and safe strategy to practice ecologically responsible anesthesia using inhalational anesthetics.

PRINCIPAL FINDINGS

Comparing the global warming potential of inhalational anesthetics, desflurane is about 20 times more potent than sevoflurane and five times more potent than isoflurane. Balanced anesthesia using low or minimal fresh gas flow (≤ 1 L·min-1) during the wash-in period and metabolic fresh gas flow (0.35 L·min-1) during steady-state maintenance reduces CO2 emissions and costs by approximately 50%. Total intravenous anesthesia and locoregional anesthesia represent further options for lowering greenhouse gas emissions.

CONCLUSION

Responsible anesthetic management choices should prioritize patient safety and consider all available options. If inhalational anesthesia is chosen, the use of minimal or metabolic fresh gas flow reduces the consumption of inhalational anesthetics significantly. Nitrous oxide should be avoided entirely as it contributes to depletion of the ozone layer, and desflurane should only be used in justified exceptional cases.

Case report: Subacute combined degeneration of the spinal cord due to nitrous oxide abuse

Background

Nitrous oxide (N₂O) is an increasingly popular recreational drug. N₂O irreversibly disturbs the metabolism of vitamin B₁₂, resulting in a functional deficiency. Vitamin B₁₂ is vital for myelin synthesis and its deficiency primarily produces neurological complications. Inhaling N₂O is more common and neurological complications are more evident than before.

Case presentation

We report a young man who developed progressive limb numbness and unsteady walking after N₂O abuse. The dominant diagnosis was subacute combined degeneration of the spinal cord (SCD). The patient was admitted to the hospital and given adenosylcobalamin treatment, but his symptoms progressed significantly from before and he developed acute cognitive impairment. After methylprednisolone combined with vitamin B₁₂ treatment, symptoms significantly improved.

Conclusion

Clinicians need to understand the presentation and treatment of SCD caused by N₂O abuse. When symptoms progress despite conventional vitamin B₁₂ therapy, the combination of methylprednisolone and vitamin B₁₂ may be considered.

Functional Vitamin B12 Deficiency in Association With Nitrous Oxide Inhalation

There is a rise in the use and abuse of nitrous oxide (N₂O) as a recreational drug. In spite of the laws enforced internationally, it remains readily available and is an inexpensive mode of recreational drug. Commonly known as the ‘laughing gas’, its use as a euphoric agent is on the rise. Subsequently, the side effects are also coming to light, associated with medical, financial and social implications. It is not detected in routine drug testing. The key differential in an acute setting is often confused with the query for Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy and malabsorption syndromes associated with vitamin B12 and folate deficiencies. This is a case report of a 21-year-old male who presented to the hospital with concerns for weakness and tingling sensations in his extremities accompanied by an inability to bear weight, which he suggested to seem to be worsening over a period of three weeks. His blood tests suggest mild deficiencies of vitamin B12 and folate levels, and MRI revealed subacute combined degeneration of the cervical cord from C2 to C6. The radiologist advised to rule out B12 deficiency and the use of nitrous oxide as a recreational drug. This led to the discussion with the patient, during which he admitted to the use of nitrous oxide. Prompt management with B12 injections intramuscularly every two to three days a week for 11 days followed by folate supplements and monthly B12 injections were advised. He was also reviewed by the physiotherapy teams, and the patient agreed to not use nitrous oxide in the future as a recreational drug.

Recreational Nitrous Oxide-Induced Subacute Combined Degeneration of the Spinal Cord

There is rising use of recreational nitrous oxide (N₂O) in the community because of its availability as “whippet” canisters. Nitrous oxide use is still legal and outside the purview of the Drug Enforcement Administration (DEA). It is not detected on a routine drug screen, and patient history is key to establishing the diagnosis. We highlight a case of subacute combined degeneration in a young patient secondary to recreational nitrous oxide use, which improved with vitamin B12 replacement. A 19-year-old male with a history of recreational nitrous oxide use presented with progressive bilateral lower extremity paresthesia and ataxia. Neurological examination revealed deficits in vibration and proprioception, motor weakness, and diminished reflexes in the bilateral lower extremities. The laboratory results were significant for pancytopenia, profound vitamin B12 deficiency (55 ng/mL), and elevated methylmalonic acid (2.14 umol/L). The urine drug screen was negative. MRI showed subacute degeneration of the spinal cord dorsal column at C2-C5. Treatment with intramuscular cyanocobalamin resulted in the normalization of pancytopenia and B12 levels (573 ng/mL). The patient had partial resolution of neurological symptoms following the initiation of parenteral vitamin B12 replacement. The mechanism of subacute combined degeneration in the setting of nitrous oxide toxicity appears to be mediated by functional B12 deficiency. Oxidation of cobalt ion of vitamin B12 by nitrous oxide renders it unavailable as a coenzyme, leading to the accumulation of by-products that enter lipid metabolism, resulting in abnormal myelin synthesis, which ultimately manifests as subacute combined degeneration. Vitamin B12 deficiency of unclear etiology should raise suspicion for nitrous oxide toxicity as early initiation of replacement therapy with vitamin B12 can improve neurological function.

Recreational Nitrous Oxide Abuse: Prevalence, Neurotoxicity, and Treatment

Nitrous oxide (N₂O), also known as "laughing gas," is a colorless, nonirritating gas. Clinically, it is widely used as an inhaled anesthetic, analgesic, and anxiolytic. In recent years, recreational abuse of N₂O has become increasingly common, especially among young adults and adolescents, but many of them lack awareness of the possible side effects associated with this drug. N₂O abuse can damage multiple systems, especially the nervous system, but the exact mechanism of N₂O toxicity remains controversial. At present, an increasing number of cases of nervous system damage caused by N₂O abuse have been reported both at home and abroad. Discontinuation of N₂O use and timely supplementation with vitamin B12 are essential for a good prognosis. Long-term abuse without timely treatment will eventually lead to irreversible neurological damage. In this article, we discuss the epidemiology of N₂O abuse, neurotoxicity mechanisms, clinical manifestations, relevant auxiliary examinations, treatments, and prognosis to improve social awareness of N₂O exposure risk, especially among users and clinicians.

Chemical risk in hospital settings: Overview on monitoring strategies and international regulatory aspects

Chemical risk in hospital settings is a growing concern that health professionals and supervisory authorities must deal with daily. Exposure to chemical risk is quite different depending on the hospital department involved and might origin from multiple sources, such as the use of sterilizing agents, disinfectants, detergents, solvents, heavy metals, dangerous drugs, and anesthetic gases. Improving prevention procedures and constantly monitoring the presence and level of potentially toxic substances, both in workers (biological monitoring) and in working environments (environmental monitoring), might significantly reduce the risk of exposure and contaminations. The purpose of this article is to present an overview on this subject, which includes the current international regulations, the chemical pollutants to which medical and paramedical personnel are mainly exposed, and the strategies developed to improve safety conditions for all healthcare workers.

State-of-the-Art of Strategies to Reduce Exhaust Emissions from Diesel Engine Vehicles

Compression ignition engines play a significant role in the development of a country. They are widely used due to their innate properties such as high efficiency, high power output, and durability. However, they are considered one of the key contributors to transport-related emission and have recently been identified as carcinogenic. Thus, it is important to modify the designs and processes before, during, and after combustion to reduce the emissions to meet the strict emission regulations. The paper discusses the pros and cons of different strategies to reduce emissions of a diesel engine. An overview of various techniques to modify the pre-combustion engine design aspects has been discussed first. After that, fuel modifications techniques during combustion to improve the fuel properties to reduce the engine-out emission is discussed. Finally, post-combustion after-treatment devices are briefly discussed, which help improve the air quality of our environment.

No Laughing Matter: Presence, Consumption Trends, Drug Awareness, and Perceptions of "Hippy Crack" (Nitrous Oxide) among Young Adults in England

In clinical settings, nitrous oxide gas is a safe anesthetic used during childbirth, in dentistry, and to relieve anxiety in emergencies. Colloquially known as "hippy crack"' or "laughing gas," it is increasingly taken recreationally for its euphoric and relaxing effects and hallucinogenic properties. Using a self-reported survey, we gathered quantitative and qualitative information on users and non-users of hippy crack among a young population regarding: consumption patterns, knowledge, risk awareness and intentions toward future abuse. Quantitative responses from a total of 140 participants were analyzed for frequencies and relationships, whereas qualitative data were evaluated via identifying the reoccurring themes. Overall, 77.1% (n = 108) had heard of hippy crack and 27.9% (n = 39) admitted to past-year use. Prior users mostly indicated intended future use, had an average low number of past-year uses but some with > 20 occasions, had a varied number of inhalations per occasion (often 1-10) with an effect lasting up to 5 min, and a majority preferred social rather than lone use. For non-users, 79.2% said they would take hippy crack with the vast majority (94%) preferring a social setting. The results show a concerning gap between available evidence and awareness of side effects. Despite serious reported side effects, including psychosis and myeloneuropathy-especially on the young developing brain-only a minority (29.3%) was aware of any side effects. In contrast, in a hypothetical scenario depicting a first social encounter with hippy crack, the qualitative responses were in contrast to qualitative outcomes revealing that participants would try (n = 30)/not try (n = 25) it, would feel under pressure to try it (n = 6) with only 11 opting to exit the situation. In summary, this first report of trends and perceptions of the use of hippy crack among young adults in the England highlights a lack of concern with side effects, coupled to a willingness to partake. Because typical users are young with risks to the still developing brain, education about the nitrous oxide abuse is warranted to prevent impaired brain development. Further studies to investigate the possible effects of nitrous oxide on the developing brain in young adults would advance meaningful prevention.

Does environmental exposure to the greenhouse gas, N2O, contribute to etiological factors in neurodevelopmental disorders? A mini-review of the evidence

BACKGROUND

Neurodevelopmental disorders are increasing in prevalence worldwide. Previous work suggests that exposure to the environmental air pollutant and greenhouse gas - nitrous oxide (N₂O) - may be an etiological factor in neurodevelopmental disorders through the targeting of several neural correlates.

METHODOLOGY

While a number of recent systematic reviews have addressed the role of general anesthesia in the surgical setting and neurodevelopmental outcomes, a narrative mini-review was conducted to first define and characterize the relevant variables (i.e., N₂O, attention-deficit hyperactivity disorder [ADHD] and autism spectrum disorders [ASD]) and their potential interactions into a coherent, hypothesis-generating work. The narrative mini-review merges basic principles in environmental science, anesthesiology, and psychiatry to more fully develop the novel hypotheses that neurodevelopmental impairment found in conditions like ADHD and ASD may be due to exposure to the increasing air pollutant, N₂O.

RESULTS

The results of the present mini-review indicate that exposure to N₂O, even at non-toxic doses, may modulate central neurotransmission and target many neural substrates directly implicated in neurodevelopmental disorders, including the glutamatergic, opioidergic, cholinergic, and dopaminergic systems. Epidemiological studies also indicate that early and repeated exposure to general anesthesia, including N₂O, may contribute to later adverse neurodevelopmental outcomes in children.

CONCLUSIONS

The current evidence and subsequent hypotheses suggest that a renewed interest be taken in the toxicological assessment of environmental N₂O exposure using validated biomarkers and psychiatric endpoints. Given the relevance of N₂O as a greenhouse gas, societies may also wish to engage in a more robust monitoring and reporting of N₂O levels in the environment for climactic benefit as well.

Up: The rise of nitrous oxide abuse. An international survey of contemporary nitrous oxide use

In recent years the recreational use of inhaled nitrous oxide gas (N2O) is becoming increasingly popular, yet little is known about the characteristics of its users or the effects they experience. This paper presents original research from the 2014 Global Drug Survey (GDS) (n=74,864). GDS runs the largest survey of recreational drug use in the world. The findings confirm N2O as a very common drug of use, in particular in the UK and US (38.6% and 29.4% lifetime prevalence). In the UK N2O was reported to be the eighth most commonly used substance. N2O was generally consumed via gas-filled balloons, at festivals and clubs where use of other substances was common. The vast majority of users use infrequently, and their use is not associated with significant harm. However, there appears to be a subpopulation of heavy users who may be using in a dependent pattern. Analysis of last year N2O users (n=4883), confirms that N2O is associated with hallucinations and confusion (which may be the desired effects) and persistent numbness and accidental injury (27.8%, 23.9%, 4.3% and 1.2% of last year users, respectively). Accidental injury is associated with the highest number of 'hits' per session, suggesting a dose-response relationship. The presence of significant harm is discussed in the light of public education on the risks of N2O use and harm-reduction strategies appropriate to N2O use. Further work needs to be completed to confirm the presence of persistent neurological symptoms in recreational users.

Neurologic, psychiatric, and other medical manifestations of nitrous oxide abuse: A systematic review of the case literature

BACKGROUND/OBJECTIVES

Nitrous oxide (N2 O) is known to have abuse potential, although debate regarding the toxic effects of such abuse continues. Our objective was to review the case literature and present the neurologic, psychiatric and medical consequences of N2 O abuse.

METHODS

A systematic literature review was completed for case reports using keywords "nitrous oxide" with "abuse/abusing" or "misuse/misusing" or "overuse/overusing" or "addiction." Non-English-language cases and cases not involving direct toxic effects of N2 O were excluded as were commentaries or personal essays. Clinical presentation, frequency of N2 O abuse, laboratory studies, imaging, ancillary tests, treatments and outcomes were collected from case reports.

RESULTS

Our review returned 335 Pubmed, 204 Web of Science, 73 PsycINFO, 6 CINAHL, 55 EMBASE and 0 Grey Literature results, and after exclusion and removal of duplicates, 91 individual cases across 77 publications were included. There were also 11 publications reporting 29 cases of death related to N2 O abuse. The majority of cases (N = 72) reported neurologic sequelae including myeloneuropathy and subacute combined degeneration, commonly (N = 39) with neuroimaging changes. Psychiatric (N = 11) effects included psychosis while other medical effects (N = 8) included pneumomediastinum and frostbite. Across all cases N2 O abuse was correlated with low or low-normal Vitamin B12 (cyanocobalamin) levels (N = 52) and occasionally elevated homocysteine and methylmalonic acid.

CONCLUSIONS/SCIENTIFIC SIGNIFICANCE

N2 O abuse represents a significant problem because of the difficulty involved with identification and the toxicity related to chronic abuse including possible death. Health professionals should be aware of the toxic effects of N2 O and be able to identify potential N2 O abuse. (Am J Addict 2016;25:358-369).

Death from Nitrous Oxide

Nitrous oxide is an inflammable gas that gives no smell or taste. It has a history of abuse as long as its clinical use, and deaths, although rare, have been reported. We describe two cases of accidental deaths related to voluntary inhalation of nitrous oxide, both found dead with a gas mask covering the face. In an attempt to find an explanation to why the victims did not react properly to oncoming hypoxia, we performed experiments where a test person was allowed to breath in a closed system, with or without nitrous oxide added. Vital signs and gas concentrations as well as subjective symptoms were recorded. The experiments indicated that the explanation to the fact that neither of the descendents had reacted to oncoming hypoxia and hypercapnia was due to the inhalation of nitrous oxide. This study raises the question whether nitrous oxide really should be easily, commercially available.

Renal angiomyolipoma and lymphangioleiomyomatosis in pregnancy

This is a literature review for management of angiomyolipoma (AML), lymphangioleiomyomatosis (LAM) and tuberous sclerosis (TS) during pregnancy, prompted by a case of a 23-year-old woman who presented with generalised itching at 31 weeks' gestation and was found to have a large vascular retroperitoneal mass in the lower pole of the left kidney. Magnetic resonance imaging (MRI) was suggestive of angiomyolipoma with multiple large aneurysms and haemorrhage within the tumour. She was delivered at 38 weeks by elective caesarean section, to avoid the risk of rupture and bleeding from the aneurysms during labour. Further imaging, with MR angiogram, computed tomography (CT) of the abdomen and pelvis and high resolution CT (HRCT) of the chest, confirmed lymphangioleiomyomatosis with left AML. She had embolisation of the AML performed twice, 8 weeks apart after delivery and subsequently had a left nephrectomy.

Robotic cardiac surgery: an anaesthetic challenge

Robotic cardiac surgery with the da Vinci robotic surgical system offers the benefits of a minimally invasive procedure, including a smaller incision and scar, reduced risk of infection, less pain and trauma, less bleeding and blood transfusion requirements, shorter hospital stay and decreased recovery time. Robotic cardiac surgery includes extracardiac and intracardiac procedures. Extracardiac procedures are often performed on a beating heart. Intracardiac procedures require the aid of peripheral cardiopulmonary bypass via a minithoracotomy. Robotic cardiac surgery, however, poses challenges to the anaesthetist, as the obligatory one-lung ventilation (OLV) and CO2 insufflation may reduce cardiac output and increase pulmonary vascular resistance, potentially resulting in hypoxaemia and haemodynamic compromise. In addition, surgery requires appropriate positioning of specialised cannulae such as an endopulmonary vent, endocoronary sinus catheter, and endoaortic clamp catheter under the guidance of transoesophageal echocardiography. Therefore, cardiac anaesthetists should have a working knowledge of these systems, OLV and haemodynamic support.

Comparison between Sevoflurane/Remifentanil and Propofol/Remifentanil Anaesthesia in Providing Conditions for Somatosensory Evoked Potential Monitoring during Scoliosis Corrective Surgery

Somatosensory evoked potential (SSEP) monitoring is an important tool in spinal corrective surgery. Anaesthesia has a significant influence on SSEP monitoring and a technique which has the least and shortest suppressant effect on SSEP while facilitating a fast recovery from anaesthesia is ideal. We compared the effect of sevoflurane/remifentanil and propofol/remifentanil anaesthesia on SSEPs during scoliosis corrective surgery and assessed patients’ clinical recovery profiles.

Twenty patients with idiopathic scoliosis receiving surgical correction with intraoperative SSEP monitoring were prospectively randomised to receive sevoflurane/remifentanil anaesthesia or propofol/remifentanil anaesthesia. During surgery, changes in anaesthesia dose and physiological variables were recorded, while SSEP was continuously monitored. A simulated ‘wake-up’ test was performed postoperatively to assess speed and quality of recovery from anaesthesia.

The effects of propofol and sevoflurane resulted in SSEP amplitude variability between 18.0% ± 3.5% to 28.7% ± 5.9% and SSEP latency variability within 1.3% ± 0.4% to 2.6% ± 1.2%. Patients receiving sevoflurane had faster suppression and faster recovery of SSEP amplitude compared to propofol (P <0.05), although propofol anaesthesia showed less within-patient variability in Cz amplitude and latency (P <0.05). On cessation of anaesthesia, time to eye-opening (5.2 vs. 16.5 minutes) and toe movement (5.4 vs. 17.4 minutes) was shorter following sevoflurane (all P <0.05).

These findings indicate that propofol produces a better SSEP signal than sevoflurane. However, adjustments in sevoflurane concentration result in faster changes in the SSEP signal than propofol. Assessment of neurological function was facilitated more rapidly after sevoflurane anaesthesia.

Pregnancy and lymphangioleiomyomatosis: anaesthetic management

Lymphangioleiomyomatosis is a rare, progressive cystic pulmonary disease related to tuberous sclerosis complex, affecting almost exclusively females of childbearing age. Progression of the disease is variable but may lead to terminal respiratory failure. As the disease may be oestrogen-dependent, it can arise de novo in pregnancy or established disease may undergo exacerbation. We report on the successful labour and delivery of such a patient and present the results of an internet survey of 30 pregnancies in 15 patients worldwide with lymphangioleiomyomatosis conducted by our patient before delivery.

A review of laparoscopy for non-obstetric–related surgery during pregnancy

PURPOSE

Similar to the general population, parturients (and their fetuses) could benefit from the reduced manipulation associated with laparoscopy. The purpose of this article is to review the current state of knowledge (both clinical and experimental) with respect to the fetal effects of maternal laparoscopy for non-obstetric-related surgery during pregnancy.

METHODS

Human and experimental animal results are examined, and we present preliminary data from our own laboratory.

CONCLUSIONS

Future experiments are proposed to further develop and refine standards of care for general surgeons and obstetricians who are presented with gravid females in abdominal distress.

Occupational hazards of inhalational anaesthetics

Occupational exposure to inhalational anaesthetics has often been associated with health hazards and reproductive toxicity, but the available evidence is weak and comes mostly from epidemiological studies that have been criticized. Studies based on registered data generally showed no association between occupational exposure to inhalational anaesthetics and reproductive effects. Animal studies also showed a lack of carcinogenicity, organ toxicity and reproductive effects with trace concentrations, as observed in operating rooms. The exception may be nitrous oxide, which in some, but not all, studies showed teratogenicity in rats chronically exposed to concentrations of 1000 p.p.m. and higher, such as may occur in unscavenged operating rooms lacking a mechanical ventilation system. Occupational exposure has also been associated with impairment of psychological functions, but these effects do not occur with trace concentrations. All in all, the scientific evidence for hazards is weak. Nonetheless, it is good practice to limit levels of exposure.

Inhaling nitrous oxide or xenon does not influence bowel wall energy balance during porcine bowel obstruction

Xenon (Xe) is less soluble than nitrous oxide (N(2)O) and hence may be more suitable during bowel obstruction. Therefore, we compared the intestinal mechanical and biochemical effects of these two gases with those of total IV anesthesia in a porcine model of small-bowel obstruction. Intestinal obstruction was induced in 33 anesthetized pigs, in 18 of which segmental ileal perfusion was reduced by partial arterial occlusion. Pigs received total IV anesthesia, Xe, or N(2)O (in 30% oxygen) for 4 h, and we determined the intraluminal pressure and volume, the arterial-ileal PCO(2) gap, and the lactate and pyruvate levels in the segmental mesenteric vein. Under both experimental conditions, Xe or N(2)O ventilation caused the volume to significantly increase with a concomitant significant increase in the intraluminal pressure during N(2)O ventilation. Regardless of the anesthesia technique, none of the biochemical variables was influenced in the animals with maintained ileal blood supply. In contrast, reducing the segmental perfusion induced pronounced alterations of all variables of bowel wall energy metabolism. The type of anesthesia, however, had no further statistically significant effect. Short-term inhalation of Xe or N(2)O seems to have no deleterious effects on the metabolic balance of the gut wall during intestinal obstruction.

IMPLICATIONS

In anesthetized pigs, short-term inhalation of xenon or nitrous oxide over 4 h when compared with total IV anesthesia had no additional deleterious effects on the metabolic balance of the gut wall during intestinal obstruction, no matter whether the arterial blood flow was reduced or not.

Neurologic problems associated with chronic nitrous oxide abuse in a non-healthcare worker

Chronic exposure to nitrous oxide (N2O) is known to be associated with hematologic and neurologic abnormalities. When this syndrome occurs, it is generally seen in health care workers, especially dentists and anesthesiologists, who have access to nitrous oxide. Here, however, we report a case of a 55-year-old non-healthcare worker who presented with multiple neurological abnormalities. His serum vitamin B12 level was low but his Shilling test was normal. His neurologic symptoms improved after cessation of inhaling nitrous oxide and starting vitamin B12 therapy. Physicians should consider nitrous oxide abuse in non-healthcare workers presenting with neurologic symptom of unclear cause.

Pediatric trauma. Anesthesia management

Prevention of childhood injury remains the cornerstone of reducing the number of children who present for post-traumatic surgical intervention. Beyond prevention, the next best step is the accurate diagnosis and treatment of traumatic injury. Anesthesiologists contribute to this step by providing timely resuscitation and optimal care to avoid secondary injury. This article classifies trauma in children into different categories depending on the location of the injury. Trauma, of course, is rarely focal, and is often a multisystem entity. With knowledge in management for each subset of trauma, one may be efficient in prioritizing injury and have a good understanding of the appropriate management of the pediatric patient with multiple traumatic injuries.

Reserve nitrous oxide cylinders on anaesthetic machines. A survey of attitudes and equipment at a large DGH

The presence of reserve nitrous oxide cylinders on anaesthetic machines is not necessary and potentially hazardous, wasteful and polluting. Although reserve nitrous oxide cylinders are routinely present on the anaesthetic machines in many hospitals in the UK, it is our concern that they are not checked or maintained properly. We examined a sample of cylinders and surveyed the practice amongst the anaesthetic staff in our Department with an anonymous questionnaire. This confirmed that: (1) the equipment is not properly maintained, 68% of cylinders sampled having passed a 3-year expiry date; (2) checks are of little practical use, are not routinely performed by anaesthetists, and only 46% of respondents routinely check the nitrous oxide cylinders. In conclusion, the nitrous oxide cylinders are not properly checked or maintained and may represent a safety hazard.

Immunological disturbances in anaesthetic personnel chronically exposed to high occupational concentrations of nitrous oxide and halothane

Immunological changes in anaesthetic personnel exposed to occupational concentrations of holothane and nitrous oxide 10-60 times greater than the advised maximum were studied during routine work and after 3-4 weeks holiday. Red cell count, haemoglobin concentration and haematocrit decreased during exposure although not significantly, in comparison with a control group, but all had increased significantly after the holidays. Other changes were altered neutrophils and lymphocyte counts. Basophils disappeared from the blood during the exposure. Monocytes were not affected during the exposure, but increased after its cessation. Percentages of CD2 and CD4 lymphocytes increased significantly, but numbers of cells in T lymphocyte subpopulations (total, helper and cytotoxic/suppressor lymphocytes) were not significantly altered. B lymphocytes were most strongly affected: they decreased during working periods and did not recover after holidays. Natural killer (NK) cells, on the other hand, decreased significantly during exposure, but fully recovered during holidays. After stimulation with mitogens, phytohaemaglutin, concanavalin A, and pokeweed, lymphocytes from exposed personnel incorporated significantly more 3H-thymidine than those from control subjects, but stimulation indices did not differ. The natural killer-cell activity, serum Ig concentrations and phagocytosis by granulocytes were not altered.

Nitrous oxide analgesia in a pediatric emergency department

Nitrous oxide (N2O) has been shown to be an effective analgesic in adult medical outpatients, yet no prospective studies of its use in the pediatric medical outpatient exist. Thirty-four children requiring laceration repair were randomly assigned to one of two treatment groups: 30% N2O/70% O2 or a placebo, 100% O2. Pain behavior, using the observer-scored Children's Hospital of Eastern Ontario Pain Scale, was assessed by double-blind techniques, before and during the laceration repair. Less pain behavior was seen in children less than 8 years old who received the N2O mixture than in those receiving the placebo. In patients 8 or more years old who received N2O, there was a significant improvement in the second evaluation as compared with those receiving only O2 during the procedure (P less than .05). There also was a smaller increase in pain behavior, from the first to the second evaluation, in those receiving N2O (P less than .05). No side effects were encountered. The authors conclude that continuous N2O inhalation is an effective and painless analgesic in children for outpatient procedures. More effective analgesia will likely occur with 40% to 50% N2O, although these concentrations remain to be studied in pediatric outpatients.