Benzocaine Spray Research Articles

Toxic Methemoglobinemia Complicating Transesophageal Echocardiography

We describe the case of a patient with acute methemoglobinemia after topical oropharyngeal anesthesia with benzocaine spray.

Ineffectiveness of Topical Benzocaine Spray During Colposcopy

BACKGROUND Colposcopic evaluation can cause patients to experience pain and anxiety. This study investigated the use of benzocaine spray, a topical anesthetic, and its effects on pain and anxiety associated with colposcopy and colposcopic biopsy. METHODS The study was a double-blind, placebo-controlled trial of the effectiveness of benzocaine spray applied to the cervix immediately before colposcopic examination, cervical biopsy, or endocervical curettage in patients of a family practice center. Prior to the gynecologic procedure the patient's cervix was sprayed with either benzocaine spray or matching placebo spray. After waiting at least 30 seconds the clinician started the procedure. Pain and anxiety, measured on 10-cm visual analog scales, were determined at the following times: (1) before the start of the gynecologic examination; (2) immediately before using the spray; (3) immediately after using the spray; and, (4) after the procedure was completed. RESULTS Of 58 consecutive patients who underwent colposcopy, 36 patients were eligible for the trial and were evaluated. Participants were similar to patients not participating with regard to race, gravidity, and parity. Statistical analysis found significant differences in both pain and anxiety scores over time (repeated measures multivariate ANOVA, P < .0001), but no difference between the use of active drug and placebo. Pain scores increased significantly after application of either benzocaine or placebo spray before the start of the procedure (average increase 1.3 cm, P < .0001). CONCLUSIONS Benzocaine, in a spray vehicle, confers no benefit when used to decrease pain and anxiety in women undergoing colposcopic procedures.

Local Anesthetic‐Induced Methemoglobinemia During Transesophageal Echocardiography

We report a case of methemoglobinemia that occurred following topical benzocaine spray to the throat, leading to cancellation of the transesophageal echocardiography (TEE) procedure. Since the condition is potentially fatal, increased awareness of this disorder should result in its early recognition and treatment.

Methemoglobinemia from Benzocaine Spray Before Bronchoscopy Two Case Reports and Review of the Literature

Benzocaine sprays are often used before bronchoscopy to anesthetize the oropharynx. Two cases of patients with methemoglobinemia resulting from the application of topical benzocaine are reported. This diagnosis was initially suspected because both patients developed acute cyanosis after bronchoscopy, and was confirmed by cooximetry of arterial blood samples. One patient responded promptly to intravenous administration of methylene blue, and the other patient required no intervention. A review of the literature regarding Benzocaine-induced methemoglobinemia is presented, including predisposing factors, mechanism of action, diagnosis, and treatment.

Toxic methemoglobinemia after topical anesthesia for transesophageal echocardiography

Topical benzocaine spray is an anesthetic agent that is commonly used during transesophageal echocardiography (TEE). This agent is believed to be relatively safe because of very low systemic absorption. We report a case of toxic methemoglobinemia induced by benzocaine used for pharyngeal anesthesia during TEE. Physicians who perform TEE and use benzocaine or other topical anesthetics need to be familiar with this potential complication and have the necessary treatment readily available.

METHEMOGLOBINEMIA INDUCED BY BENZOCAINE SPRAY PRIOR TO ESOPHAGEAL MANOMETRY IN AN ADOLESCENT. 751

Esophageal manometry is best performed without anesthesia or sedation. However, with particularly anxious patients, some form of topical anesthetic or sedation may be used. Benzocaine spray, thought to be a safe topical anesthetic, has been reported to induce methemoglobinemia in adults(Gastroenterology 1990;98:211-213). However, this has not been reported to occur in children. We report an 11½-year-old Caucasian male with a history of achalasia. He developed methemoglobinemia as a result of topical benzocaine sprayed onto his pharynx prior to esophageal manometry at 10:10 a.m. (see table). Within 25 minutes of receiving the benzocaine spray, his oxygen saturation (%) dropped from 98% to 88%, and he became cyanotic. His oxygen saturation continued to drop even though he was receiving oxygen therapy and maintained a Po2 of> 300 mmHg. He remained awake and alert. Arterial blood (AB) for oxygen content was noted to be brown, and the diagnosis of methemoglobinemia was made. Blood for methemoglobin concentration showed an increase to 16% and 24% on two occasions(<1% WNL). Intravenous methylene blue (M.B.) was administered; 2 doses of 35 mg each (1 mg/kg ×2). Within 12 minutes of the second dose, the patient was pink, and after 22 minutes his oxygen saturation was 91%.

Benzocaine-induced methemoglobinemia attributed to topical application of the anesthetic in several laboratory animal species

Summary In a screening study, a common benzocaine-containing anesthetic was topically applied to the following species: dogs (n = 11), domestic shorthair cats (n = 38), Long-Evans rats (n = 22), Sprague-Dawley rats (n = 11), ferrets (n = 6), rhesus monkeys (n = 10), cynomolgus monkeys (n = 10), owl monkeys (n = 10), New Zealand White rabbits (n = 18), miniature pigs (n = 9), ICR mice (n = 4), C3H mice (n = 4), and C57BL/10SnJ mice (n = 24). All animals, except mice and rats, received a 2-second spray to the mucous membranes of the nasopharynx for an estimated dose of 56 mg. A 2-second spray to rodents' oral mucous membranes deliverd too great a volume of fluid for these animals; therefore, an equivalent dose was applied to the oral mucosa membranes by use of a 23-gauge needle and syringe. Initial (baseline) blood samples, as well as 4 blood samples taken every 15 minutes after drug application, were analyzed for methemoglobin (MHb), using an oximeter. Positive MHb response (&gt; 3 sd above baseline) was seen in individuals of all groups. The study was repeated in dogs several months later to confirm low response. Response to benzocaine spray was observed in most animals tested, with response peaking between 15 and 30 minutes after dosing. Positive MHb response ranged from 3.5 to 38%, was detected in &gt; 95% of individual animals, and ranged from 15 to 60 minutes after drug administration. Responses were variable because of the screening nature of the study and the topical route of drug administration, but the highest responses were observed in rabbits and cats, and the lowest were seen in mice and dogs. Methemoglobin could be a confounding variable for several types of studies; investigators should consider this toxicity of benzocaine-containing topical anesthetics and use appropriate alternative methods or drugs (ie, lidocaine).

Methemoglobinemia as a complication of 20% benzocaine spray for endoscopy

Topical 20% benzocaine (Hurricaine, Beutlich, Inc., Niles, Ill.) spray is frequently used for oral anesthesia before upper endoscopy. Side effects attributed to this agent are exceedingly rare. The author reports one of these rare complications, drug-induced methemoglobinemia, in a patient with methemoglobin reductase deficiency. The mechanisms for the development of methemoglobinemia and its treatment are reviewed.

Methemoglobinemia induced by local anesthetics

A case of methemoglobinemia secondary to topical local anesthetic agents is reported. A 28-year-old, 80-kg white man was admitted to a hospital for respiratory distress two days after an accident. During intubation, Cetacaine (benzocaine, butamben, and tetracaine) spray and Americaine (benzocaine) ointment were used topically for local anesthesia. Ninety minutes later, the patient was cyanotic despite ventilation, and an arterial blood sample was chocolate-brown and contained 29 d/dl methemoglobin (normal less than 1.7 g/ dl). Methylene blue, 80 mg as a 1% solution in 5% dextrose in water, was infused over 20 minutes, and hte patient's cyanosis disappeared within the next 30 minutes. The following afternoon, the patient was reintubated, using 4% lidocaine and benzocaine as local anesthetics. He again developed cyanosis. Methylene blue again cleared the cyanosis. Abnormal hemoglobin variants and NADH-methemoglobin reductase deficiency were ruled out as sources of methemoglobinemia. A discussion of methemoglobinemia, including biochemistry, pathogenesis, symptomatology, and management, is presented. If cyanosis occurs following application of local anesthetics, methemoglobinemia secondary to these drugs should be considered in the differential diagnosis.

Acute methemoglobinemia induced by topical benzocaine and lidocaine

• Acute methemoglobinemia may result from the use of several local anesthetic agents. Benzocaine (Cetacaine) spray has been shown previously to cause methemoglobinemia in two patients when applied topically to the mucous membranes. We describe a patient with respiratory failure following trauma who had two episodes of acute methemoglobinemia, one after the topical application of benzocaine and the second following lidocaine administration for endotracheal intubation. The episodes occurred more than 20 hours apart, and no other drugs known to induce methemoglobinemia were given. On both occasions, intravenous methylene blue was effective in correcting the disorder. (<i>Arch Intern Med</i>140:1508-1509, 1980)

Acute Methemoglobinemia Induced by Topical Benzocaine and Lidocaine

Acute methemoglobinemia may result from the use of several local anesthetic agents. Benzocaine (Cetacaine) spray has been shown previously to cause methemoglobinemia in two patients when applied topically to the mucous membranes. We describe a patient with respiratory failure following trauma who had two episodes of acute methemoglobinemia, one after the topical application of benzocaine and the second following lidocaine administration for endotracheal intubation. The episodes occurred more than 20 hours apart, and no other drugs known to induce methemoglobinemia were given. On both occasions, intravenous methylene blue was effective in correcting the disorder.