Tympanic membrane rupture after anesthesia with nitrous oxide

Acute Intraoperative Tympanic Membrane Rupture in Patient Anesthetized With Desflurane Without Nitrous Oxide: A Case Report

We report a case of acute intraoperative tympanic membrane (TM) rupture in a patient anesthetized with desflurane without N2O. The patient was undergoing endoscopic retrograde cholangiopancreatography (ERCP) to treat ascending cholangitis. TM rupture is known to occur with N2O but has not been reported in the literature with the use of inhaled volatile anesthetics without N2O. We suspect that several factors contributed to this complication, including prone positioning, a remote history of ear trauma, and the selection of desflurane as the maintenance anesthetic as opposed to a vapor with a higher blood-gas partition coefficient.

Effects of Total Intravenous Anesthesia and Low- and High-Flow Anesthesia Implementation on Middle Ear Pressure

Background

The middle ear is an air-filled lacuna in the temporal bone. Inhaled anesthetic agents increase the pressure of this lacuna. Therefore, attention must be paid in choosing not only anesthetic agents but also anesthetic method.

Aim

This study compared the effects of high-flow total intravenous anesthesia (TIVA) and low- and high-flow desflurane anesthesia on middle ear pressure.

Study Design

Randomized prospective double-blind study.

Methods

In this retrospective double-blind study, 90 patients (20–65 years old) scheduled to undergo elective thyroidectomies were divided into three randomized anesthesia groups: high-flow desflurane (Group I), low-flow desflurane (Group II), and high-flow TIVA (propofol, remifentanil) (Group III). The hemodynamic and respiratory parameters and tympanometry were measured before induction (T1), 10 minutes after intubation (T2), 10 minutes before the end of the operation (T3), and 5 (T4), 10 (T5), 15 (T6), and 30 (T7) minutes after the operation.

Results

No statistically significant differences were found in the age, gender, weight, height, body mass index, surgery duration, and anesthetic duration (p > 0.05). There were no statistically significant differences at T1, T3, T4, T5, T6, and T7 (p > 0.007), but there was a significant difference at T2 (p < 0.001), with Groups II and III having lower pressure than Group I (p < 0.001).

Conclusion

The high-flow desflurane group had higher postinduction middle ear pressure values. Therefore, low-flow anesthesia and TIVA can be used more safely in middle ear surgeries, provided that a well-equipped anesthetic device and appropriate monitoring conditions are available.

Robot-assisted radical cystectomy: patient selection and special considerations

Robot-assisted (RA) procedures are increasingly being performed as minimally invasive surgical approaches. Less insensible losses due to a closed abdomen, smaller incisions with less retractor strain, decreased analgesic requirements, and earlier postoperative ambulation are suggested advantages of robot-assisted radical cystectomy (RARC). Patients who undergo open radical cystectomy are also candidates for RARC procedure. However, the steep Trendelenburg position and pneumoperitoneum develop a non-physiological condition. Intra-abdominal adhesions preventing the placement of the ports and patients who cannot tolerate the pneumoperitoneum and/or steep Trendelenburg position are special contraindications of RARC. Besides, body mass index >30 kg/m2, presence of extravesical disease, bulky lymphadenopathy, previous vascular surgery, previous distal colorectal surgery, previous pelvic radiation, previous pelvic trauma, and/or preexisting cardiovascular/pulmonary disease that is compromised with positioning are not certainly contraindicated but unwanted conditions in which the RARC may be performed successfully as the surgeons gain experience.

Effects of steep Trendelenburg position and pneumoperitoneum on middleear pressure in patients undergoing robotic radical prostatectomy

BACKGROUND/AIM

The aim of this study was to quantify the changes in middle ear pressure (MEP) during robot-assisted radical prostatectomy (RARP).

MATERIALS AND METHODS

Thirty patients undergoing RARP were included in this study. MEP was obtained at the following time points: awake (T1), postintubation (T2), pneumoperitoneum + 1 h of Trendelenburg position (T3), pneumoperitoneum + 2 h of Trendelenburg position (T4), pneumoperitoneum + 3 h of Trendelenburg position (T5), desufflation + supine position (T6), and 1 h after extubation in the postanesthesia care unit (T7). Heart rate, mean arterial pressure (MAP), peak airway pressure (PAP), tidal volume, minute ventilation, EtCO₂, and blood gas values were recorded.

RESULTS

MEP was significantly higher at T4, T5, T6, and T7 as compared to T1 values. PAP values were significantly increased at T3, T4, and T5 compared to T2. MAP values at T3, T4, and T5 were significantly higher compared to T1. PaCO₂ increased significantly at T4, T5, and T6 and pH decreased significantly at T4 and T5 when compared to T2.

CONCLUSION

The combination of steep Trendelenburg position and pneumoperitoneum during RARP caused a significant increase in MEP, PaCO₂, and EtCO₂ levels. This propensity for increased MEP may cause problems in patients with preexisting ear disease.

Recreational nitrous oxide use: Prevalence and risks

Nitrous oxide (N2O; laughing gas) is clinically used as a safe anesthetic (dentistry, ambulance, childbirth) and appreciated for its anti-anxiety effect. Since five years, recreational use of N2O is rapidly increasing especially in the dance and festival scene. In the UK, N2O is the second most popular recreational drug after cannabis. In most countries, nitrous oxide is a legal drug that is widely available and cheap. Last month prevalence of use among clubbers and ravers ranges between 40 and almost 80 percent. Following one inhalation, mostly from a balloon, a euphoric, pleasant, joyful, empathogenic and sometimes hallucinogenic effect is rapidly induced (within 10 s) and disappears within some minutes. Recreational N2O use is generally moderate with most users taking less than 10 balloons of N2O per episode and about 80% of the users having less than 10 episodes per year. Side effects of N2O include transient dizziness, dissociation, disorientation, loss of balance, impaired memory and cognition, and weakness in the legs. When intoxicated accidents like tripping and falling may occur. Some fatal accidents have been reported due to due to asphyxia (hypoxia). Heavy or sustained use of N2O inactivates vitamin B12, resulting in a functional vitamin B12 deficiency and initially causing numbness in fingers, which may further progress to peripheral neuropathy and megaloblastic anemia. N2O use does not seem to result in dependence. Considering the generally modest use of N2O and its relative safety, it is not necessary to take legal measures. However, (potential) users should be informed about the risk of vitamin B12-deficiency related neurological and hematological effects associated with heavy use.

Effects of desflurane on middle ear pressure

OBJECTIVE

To evaluate the effects of desflurane on middle ear pressure.

STUDY DESIGN

A prospective clinical study.

METHODS

In this study, 38 ears of 19 male children that were scheduled for circumcision were included. Baseline tympanometry reading was performed on each ear just before anesthesia. After induction anesthesia with propofol a laryngeal mask was applied and desflurane administration was started. The next tympanometry reading was taken at 5th, 10th and 15th minute after administration and at the 10th minute after the cessation of desflurane. Data were analysed using Wilcoxon test.

RESULTS

Mean MEP values before anesthesia in 38 ears of 19 boys were -10.32+/-33.14. After starting the administration of desflurane 5th minute mean value was 71.15+/-60.42, at the 10 th minute 111.56+/-59.03 and at the 15th minute it increased to 120.50+/-54.14, and these measurements were significantly higher than the starting value (p<0.001). After cessation of desflurane mean MEP value dropped to 57.56+/-79.06, but compared with the starting value this was also significantly higher (p<0.001).

CONCLUSION

Desflurane may increase the middle ear pressure and it may be unsuitable for certain middle ear surgeries.

Effects of sevoflurane and TIVA with propofol on middle ear pressure

OBJECTIVE

To evaluate the effects of sevoflurane and TIVA with propofol on middle ear pressure and to show the importance of anesthesia without using any inhalational agents during middle ear surgery.

STUDY DESIGN

A prospective, randomized controlled clinical study.

METHODS

In this study, 25 male children that were scheduled for circumcision were randomised into two groups. Group I (n=13) received TIVA with propofol and group II (n=12) received sevoflurane. Baseline tympanometry reading was performed on each ear just before anesthesia. The next tympanometry reading was taken 10min after applying the laryngeal mask. Data were analysed by Mann-Whitney U (between groups) and Wilcoxon tests (within groups).

RESULTS

Mean MEP values in 26 ears of 13 boys in group I did not show any significant difference before and after the anesthesia with propofol (p>0.05). In group II mean MEP values in 24 ears of 12 boys showed a significant increase after the anesthesia with sevoflurane (p<0.001). No significant difference was found between the MEP values of the two groups before the anesthesia (p>0.05), and MEP values measured during the anesthesia were significantly higher in group II (p=0.007).

CONCLUSION

Sevoflurane may increase the middle ear pressure and TIVA with propofol may be used in middle ear operations more safely than sevoflurane.

Middle Ear Pressure Changes During Anesthesia With or Without Nitrous Oxide are Similar Among Airway Devices

We tested the hypothesis that middle ear pressure (MEP) is influenced by the choice of airway device during anesthesia with or without nitrous oxide (N2O) in the gas mixture. Eighty consecutive anesthetized, paralyzed ventilated patients (ASA physical status I-II, 18-65 yr) were randomly allocated for airway management with the orally inserted tracheal tube, classic laryngeal mask airway, ProSeal laryngeal mask airway, or laryngeal tube suction with or without N2O 66% in the gas mixture. MEP was measured from both ears in random order by a blinded observer before induction of anesthesia and every 10 min for 70 min. In the N2O groups, N2O was changed to air after 40 min. There were no differences in MEP among the airway devices in the N2O or air groups. MEP was unchanged in the air groups but increased in the N2O groups with N2O (P < 0.0001) and decreased with air (P < 0.02). Baseline values for MEP were similar, but MEP was always higher for the N2O groups (P < 0.001). We conclude that the choice of airway device does not influence MEP among orally inserted tracheal tube, classic laryngeal mask airway, ProSeal laryngeal mask airway, and laryngeal tube suction during anesthesia with or without N2O in the gas mixture.

[Evaluation of tympanometric alterations in patients subject to general anesthesia with nitrous oxide]

Nitrous oxide is an inhaling gas that can increase intratympanic pressure during the anesthetic act and cause negative pressure after it is discontinued, mainly in patients with Eustachian tube dysfunction. These pressure variations may come up with clinical implications such as tympanic membrane rupture, ossicular system disarticulation, haemotympanum, barotraumas, prosthesis displacement stapaedotomy and tympanic graft lateralization after tympanoplasty, in addition to serous fluid entrance into the middle ear during the negative pressure phase. Aim: To evaluate the nitrous oxide influence on the middle ear pressure in a population without tube malfunction performing pre and postoperative tympanometry. Study design: Transversal cohort. Material and Method: A prospective study was carried out with Universitário Clementino Fraga Filho Hospital- UFRJ inpatients submitted to general anesthesia with the use of 50% nitrous oxide from April to June 2003. It was also evaluated whether the duration of surgery, associated anesthetics, presence of allergic rhinitis and nasal septal deviation could contribute to the onset of intratympanic pressure alteration. Results: The sample was made up of 50 patients and in almost half of them (48%), postoperative tympanometry alterations (type C curve) were found when comparing to preoperative tympanometric control (type A curve). Neither gender nor age interfered in the onset of postoperative tympanometry alterations, similarly to surgery duration. The associated volatile anesthetic type, nasal septal deviation and allergic rhinitis were not able to influence postoperative middle ear pressure. Conclusion: Nitrous oxide modifies intratympanic pressure during the anesthetic act and after its discontinuation.

Avaliação de alterações timpanométricas em pacientes submetidos à anestesia geral com óxido nitroso

O óxido nitroso é um gás inalatório que pode aumentar a pressão intratimpânica durante o ato anestésico, bem como causar pressão negativa após sua suspensão, principalmente em pacientes com disfunção da tuba auditiva. Estas variações pressóricas podem trazer implicações clínicas, como ruptura de membrana timpânica, desarticulação da cadeia ossicular, hemotímpano, barotrauma, deslocamento de prótese de estapedotomia e lateralização do enxerto nas timpanoplastias, além da entrada de fluido seroso na orelha média durante a fase de pressão negativa. OBJETIVO: Avaliar a influência do óxido nitroso na pressão da orelha média em uma população sem disfunção tubária, realizando timpanometria no pré e pós-operatório. FORMA DE ESTUDO: Coorte transversal. MATERIAL E MÉTODO: Foi realizado um estudo prospectivo com pacientes internados no Hospital Universitário Clementino Fraga Filho - UFRJ, submetidos à anestesia geral com o uso do óxido nitroso a 50%, durante o período de abril a julho de 2003. Avaliou-se ainda se a duração da cirurgia, anestésicos associados, presença de rinite alérgica e desvio de septo nasal poderiam influenciar no aparecimento das alterações da pressão intratimpânica. RESULTADOS: A amostra constituiu-se de 50 pacientes, encontrando-se em quase metade (48%) alterações timpanométricas no pós-operatório (curva tipo C), quando comparado às de controle do pré-operatório (curva tipo A). Sexo e idade não interferiram no aparecimento das alterações timpanométricas no pós-operatório, bem como a duração da cirurgia. O tipo de anestésico volátil associado, desvio de septo nasal e rinite alérgica não exerceram influência na pressão da orelha média no pós-operatório. CONCLUSÃO: O óxido nitroso altera a pressão na orelha média tanto na fase de indução quanto na fase de resolução anestésica.

Middle-ear pressure variations during total intravenous anesthesia with propofol, fentanyl, and ketamine

PURPOSE

As the middle-ear cavity is one of the noncompliant gas-filled cavities, an increase in middle-ear pressure (MEP) instead of volume expansion is observed with inhalation of nitrous oxide (N₂O). Changes in MEP cause many complications, such as ear pain, temporary hearing impairment, and postoperative emesis. Therefore, we investigated changes in MEP during total intravenous anesthesia (TIVA) with propofol, fentanyl, and ketamine (PFK) and inhalation of N₂O.

METHODS

Twelve patients were anesthetized with PFK until 60 min after the induction of anesthesia, and then N₂O (60%) inhalation was started. MEP was measured by impedance audiometry (ranging from -300 daPa to +200 daPa) at 10-min intervals during PFK, and at 2-min intervals after the inhalation of N₂O.

RESULTS

MEP gradually but significantly increased from the preanesthetic value of 16±8 to 34±12 (SEM) daPa 50 min after the induction of PFK. However, MEP did not exceed the normal limit. The values of MEP in all patients were more than 200 daPa within 36 min after the start of inhalation of N₂O in oxygen.

CONCLUSION

PFK had a minimal effect on MEP, whereas addition of N₂O to PFK increased MEP dramatically. Therefore, TIVA, or at least PFK, would be a better choice for patients with middle-ear or upper-airway diseases.

Effect of nitrous oxide on middle ear pressure: a comparison between inhalational anaesthesia with nitrous oxide and TIVA

We have investigated the effect of nitrous oxide on the middle ear pressure, comparing inhalational anaesthesia with nitrous oxide and halothane and total intravenous anaesthesia with propofol-alfentanil. Fifty patients with normal healthy ears were divided into two groups. In one group (n = 25), anaesthesia was induced with thiopentone 6 mg kg-1, and maintained with halothane 1% and nitrous oxide 66% in oxygen. In the other group (n = 25), anaesthesia was induced with alfentanil 25 micrograms kg-1 and propofol 2 mg kg-1, and maintained with an infusion of alfentanil 10 micrograms kg-1 min-1 for the first 10 min and then with 0.5 microgram kg-1 min-1 and with propofol 10 mg kg-1 h-1 for the first 10 min, 8 mg kg-1 h-1 for the following 10 min and 6 mg kg-1 h-1 thereafter. Patients were ventilated with an oxygen-air mixture (F1O2 = 0.33). Middle ear pressures were measured during the pre-, intra- and post-anaesthetic period in both ears. A progressive rise was observed (P < 0.05) in the first group, whereas values were within the normal limits clinically and there was no statistically significant change in those receiving total intravenous anaesthesia during the intra-anaesthetic period. The time to reach peak pressure with inhalational anaesthesia was 60 min (181.5 mmH2O) and to return to normal was 30 min (49.5 mmH2O) after cessation of nitrous oxide administration. The incidence of nausea and vomiting was less in the patients not receiving nitrous oxide.

Adverse effects of nitrous oxide

Although once considered completely devoid of complications, it is now recognised that the misuse or inappropriate use of nitrous oxide (N2O) often results in adverse side effects. Hypoxia, particularly the entity 'diffusion hypoxia', can occur with the administration of inadequate amounts of oxygen during or immediately after a N2O anaesthetic. N2O will diffuse into air-containing cavities within the body faster than nitrogen diffuses out. This results in a temporary increase in either the pressure and/or volume of the cavity depending upon the distensibility of its walls. The magnitude of the effect is proportional to the blood supply of the cavity, the concentration of N2O inhaled and the length of time the patient is exposed to N2O. Significant morbidity or even death can result from this phenomenon. A property unique to N2O is its ability to oxidise and inactivate the vitamin B12 components of certain enzymes in both animals and man. One such enzyme, methionine synthetase is essential for normal DNA production. Animal and human studies have demonstrated that the haematological, immune, neurological and reproductive systems are each affected. These adverse effects of N2O can occur after both acute (surgical) or long term (occupational) exposure to the gas. Because of its effects on the pressure and volume characteristics of air-containing spaces, N2O should not be used for patients with bowel obstruction, pneumothorax, middle ear and sinus disease, and following cerebral air-contrast studies. Many anaesthesiologists feel that use of N2O should be restricted during the first two trimesters of pregnancy because of its effects on DNA production and the experimental and epidemiological evidence that N2O causes undesirable reproductive outcomes. Since N2O affects white blood cell production and function, it has been recommended that N2O not be administered to immunosuppressed patients or to patients requiring multiple general anaesthetics. Many anaesthesiologists believe that the potential dangers of N2O are so great that it should no longer be used at all for routine clinical anaesthesia. However, the continued use of N2O remains a controversial topic since, at present, a suitable substitute gas is not available.

Negative pressure in the middle ear in children after nitrous oxide anaesthesia

A study was conducted to measure the pressure in the middle ear in healthy children, following nitrous oxide anaesthesia. Premedication with chloral hydrate and scopolamine orally was similar in all patients and awake patients received thiopentone 4-5 mg X kg-1 for induction of anaesthesia. All received nitrous oxide (66 per cent) in oxygen and halothane or isoflurane as required. Exposure to nitrous oxide varied from 17-100 minutes, mean 47 minutes. All patients developed negative pressure in one or both ears in the first day following anaesthesia. This is a higher incidence than previously reported and may be explained by the inability of children to equilibrate negative middle ear pressure via the eustachian tube.

Total intravenous anaesthesia

Total intravenous anaesthesia is a feasible alternative to the use of inhalational agents and the rationale behind such a technique is presented. The various intravenous agents are discussed, particularly with regard to their suitability for this form of anaesthesia, and their physiological effects compared with those of the inhalational anaesthetics. Some of the problems associated with the use of total intravenous anaesthesia are mentioned.