Use of Nitrous Oxide in Dermatology: A Systematic Review

Nitrous Oxide Improves Tissue Perfusion in Vascular Occlusion Management

Filler-related vascular occlusion (VO) treatment remains challenging despite established protocols, including high-dose pulsed hyaluronidase injections and ultrasound-guided targeted injections. Managing patients' pain and anxiety during treatment presents additional difficulties. Nitrous oxide (N₂O) has been found to be effective for analgesia and anxiolysis in minor procedures, with a 55% reduction in photodynamic therapy pain, and a visual analog scale reduction from 6.6 to 2.9 for aesthetic laser treatment pain. Use of N₂O for analgesia, anxiolysis, or improvement of perfusion in VO has not been previously reported. We present two cases of filler-related VO management with high-dose hourly hyaluronidase injections and adjunctive use of self-administered 50% N₂O. Pain and anxiety of the treatment were self-reported by the patients. Capillary refill and livedo reticularis were monitored for establishing VO diagnosis and treatment outcome. In both cases, self-administration of N₂O led to contemporaneous improvement in skin perfusion. Patients reported decreased anxiety and pain during treatment. Hyaluronidase treatment led to permanent resolution of occlusion symptoms. N₂O presents a promising adjunctive treatment option for relief of pain and anxiety, and potentially additional perfusion improvement. Further investigation is necessary to better define N₂O's role in treating VO.

Sclerotherapy of lower limb veins: Indications, contraindications and treatment strategies to prevent complications - A consensus document of the International Union of Phlebology-2023

BACKGROUND

Sclerotherapy is a non-invasive procedure commonly used to treat superficial venous disease, vascular malformations and other ectatic vascular lesions. While extremely rare, sclerotherapy may be complicated by serious adverse events.

OBJECTIVES

To categorise contraindications to sclerotherapy based on the available scientific evidence.

METHODS

An international, multi-disciplinary panel of phlebologists reviewed the available scientific evidence and developed consensus where evidence was lacking or limited.

RESULTS

Absolute Contraindications to sclerotherapy where the risk of harm would outweigh any benefits include known hypersensitivity to sclerosing agents; acute venous thromboembolism (VTE); severe neurological or cardiac adverse events complicating a previous sclerotherapy treatment; severe acute systemic illness or infection; and critical limb ischaemia. Relative Contraindications to sclerotherapy where the potential benefits of the proposed treatment would outweigh the risk of harm or the risks may be mitigated by other measures include pregnancy, postpartum and breastfeeding; hypercoagulable states with risk of VTE; risk of neurological adverse events; risk of cardiac adverse events and poorly controlled chronic systemic illness. Conditions and circumstances where Warnings and Precautions should be considered before proceeding with sclerotherapy include risk of cutaneous necrosis or cosmetic complications such as pigmentation and telangiectatic matting; intake of medications such as the oral contraceptive and other exogenous oestrogens, disulfiram and minocycline; and psychosocial factors and psychiatric comorbidities that may increase the risk of adverse events or compromise optimal treatment outcomes.

CONCLUSIONS

Sclerotherapy can achieve safe clinical outcomes provided that (1) patient-related risk factors and in particular all material risks are (1a) adequately identified and the risk benefit ratio is clearly and openly discussed with treatment candidates within a reasonable timeframe prior to the actual procedure; (1b) when an individual is not a suitable candidate for the proposed intervention, conservative treatment options including the option of 'no intervention as a treatment option' are discussed; (1c) complex cases are referred for treatment in controlled and standardised settings and by practitioners with more expertise in the field; (1d) only suitable individuals with no absolute contraindications or those with relative contraindications where the benefits outweigh the risks are offered intervention; (1e) if proceeding with intervention, appropriate prophylactic measures and other risk-mitigating strategies are adopted and appropriate follow-up is organised; and (2) procedure-related risk factors are minimised by ensuring the treating physicians (2a) have adequate training in general phlebology with additional training in duplex ultrasound, procedural phlebology and in particular sclerotherapy; (2b) maintain their knowledge and competency over time and (2c) review and optimise their treatment strategies and techniques on a regular basis to keep up with the ongoing progress in medical technology and contemporary scientific evidence.

Nitrous oxide intoxication: systematic literature review and proposal of new diagnostic possibilities

Background

Nitrous oxide (N2O), also called “laughing gas,” is the most commonly used inhalation anesthetic in dentistry. The N2O is no longer used, because of the long-term neurologic and cardiovascular sequelae. Due to its sedative and euphoric properties, N2O is often used for recreational use or in some erotic activities. Accidental deaths are mainly associated with the uses of N2O: death can occur from sudden cardiac arrhythmia or, most commonly, acute asphyxiation due to hypoxia. This paper aims to study the literature concerning deaths due to N2O intoxication and highlight pathological findings useful for diagnosis when the crime scene investigation does not reveal any evidence.

Materials and methods

The authors conducted the literature search by PubMed and Scopus databases, searching for articles from 1 January 1970 to 1 March 2020 using the key terms: “Nitrous oxide,” “Laughing gas,” “Hypoxic damage,” “Nitrous oxide anesthesia,” and “Nitrous oxide death.”

Results and discussion

A total of 244 articles were collected. Only 26 articles were included in the systematic review. Most of the deaths from intoxication are due to asphyxiation; the diagnosis is often difficult and immunohistochemistry could be helpful. Nitrous oxide increases the intracellular adhesion molecule expression, E- and P-Selectin (markers of the early inflammatory response), and HIF-1 α (indicative of oxidative stress during ischemia-reperfusion).

Conclusion

The macroscopic and microscopic signs of N2O intoxication are non-specific, but N2O has been proven to cause hypoxic damage to the brain. The suspicion of the presence of the gas in the environment should guide the pathologist. Tissue analyzes provide important information; immunohistochemical stains can confirm hypoxic damage through the use of markers such as HIF-1 α, E-Selectin, and P-Selectin.

Dermatological Conditions Inducing Acute and Chronic Pain

Pain is a common condition in dermatology. The aim of this review is to analyse the characteristics of pain in dermatology. Some skin diseases are conventionally known to cause pain; e.g. ulcers, pyoderma gangrenosum and herpes zoster. Common dermatoses, such as psoriasis or atopic dermatitis, can also cause significant pain. Some conditions are characterized by neuropathic pain and/or pruritus, without visible primary lesions: e.g. the neurocutaneous diseases, including small fibre neuropathies. Patients often fear pain in skin surgery; however, surgical procedures are rather well tolerated and any pain is mainly due to administration of local anaesthetic. Some therapies may also be uncomfortable for the patient, such as photodynamic therapy or aesthetic procedures. Thus, pain in dermatology is common, and its aetiology and characteristics are very varied. Knowledge of the different situations that cause pain will enable dermatologists to propose suitable analgesic solutions.

Important reminder: nitrous oxide (N2O) as a cause of functional vitamin B12 deficiency

A 32-year-old woman who misused multiple substances, including nitrous oxide (N₂O), sought medical advice after she subacutely developed bilateral lower extremity weakness without a sensory level but with ataxia-her significant other developed similar symptoms with vitamin B₁₂ deficiency due to N₂O intake. Laboratory results revealed macrocytic anaemia despite normal B₁₂ and folate levels, with serum markers pointing towards functional cobalamin deficiency. Spinal MRIs and cerebrospinal fluid analysis were unremarkable. Our patient was treated with vitamin B₁₂ supplementation with an encouraging response.

Virtual reality vs. Kalinox® for management of pain in intensive care unit after cardiac surgery: a randomized study

Introduction

The management of pain and anxiety remains a challenge in the intensive care unit. By distracting patients, virtual reality (VR) may have a role in painful procedures. We compared VR vs. an inhaled equimolar mixture of N₂O and O₂ (Kalinox®) for pain and anxiety management during the removal of chest drains after cardiac surgery.

Methods

Prospective, non-inferiority, open-label study. Patients were randomized, for Kalinox® or VR session during drain removal. The analgesia/nociception index (ANI) was monitored during the procedure for objective assessment of pain and anxiety. The primary endpoint was the ΔANI (ANI_min − ANI₀) during the procedure, based on ANIm (average on 4 min). We prespecified VR as non-inferior to Kalinox® with a margin of 3 points. Self-reported pain and anxiety were also analysed using numeric rate scale (NRS).

Results

200 patients were included, 99 in the VR group and 101 in the Kalinox® group; 90 patients were analysed in both groups in per-protocol analysis. The median age was 68.0 years [60.0–74.8]. The ΔANI was − 15.1 ± 12.9 in the Kalinox® group and − 15.7 ± 11.6 in the VR group (NS). The mean difference was, therefore, − 0.6 [− 3.6 to 2.4], including the non-inferiority margin of 3. Patients in the VR group had a significantly higher pain NRS scale immediately after the drain removal, 5.0 [3.0–7.0] vs. 3.0 [2.0–6.0], p = 0.009, but no difference 10 min after. NRS of anxiety did not differ between the two groups.

Conclusion

Based on the ANI, the current study showed that VR did not reach the statistical requirements for a proven non-inferiority vs. Kalinox® in managing pain and anxiety during chest drain removal. Moreover, VR was less effective based on NRS. More studies are needed to determine if VR might have a place in the overall approach to pain and anxiety in intensive care units.

Trial registration NCT, NCT03956264. Registered 20 May 2019, https://clinicaltrials.gov/ct2/show/NCT03956264

Nitrous Oxide Reduces Pain Associated With Local Anesthetic Injections

BACKGROUND

Local anesthetic injections can be painful and distressing.

OBJECTIVE

The aim of this study was to determine whether nitrous oxide, ice, vibration, or topical anesthetic improves analgesia for local anesthetic injections.

METHOD

A cohort study of 400 patients undergoing Mohs micrographic surgery with local anesthetic was conducted. Patients received no intervention (n = 200), ice (n = 50), topical anesthetic cream (n = 50), vibration device (n = 50), or nitrous oxide (n = 50). Pain was rated using the Visual Analogue Scale (VAS) and Wong-Baker FACES Pain Rating Scale.

RESULTS

Without intervention, mean VAS was 4.2 and FACES was 4.6. Nitrous oxide was the most successful in reducing pain (mean VAS 1.6 vs. 4.2, P < .01, FACES 1.2 vs. 4.6, P < .01). Topical ice reduced pain (mean VAS 3.0 vs. 4.2, P < .01, FACES 3.0 vs. 4.6, P < .01). Vibration reduced pain (mean VAS 3.5 vs. 4.2, P < .01, FACES 3.6 vs. 4.6, P < .01). Higher pain scores were associated with age <50 (P = .02), male sex (P = .05), and surgery on the nose, lip, ear, or eyelid (P = .02).

CONCLUSION

Nitrous oxide, ice, and vibration reduce injection pain. These interventions are especially useful for younger males undergoing surgery on the nose, lip, ear, or eyelid.