Intraocular pressure during rapid sequence induction: use of moderate-dose sufentanil or fentanyl and vecuronium or atracurium

We studied the effect of rapid sequence induction of anaesthesia on intraocular pressure in physically fit, ASA class I or II patients using combinations of sufentanil (1 microgram/kg), or fentanyl (5 micrograms/kg) and vecuronium (0.2 mg/kg) or atracurium (1.0 mg/kg). All patients received thiopentone (5 mg/kg), following which those in group 1 received sufentanil and vecuronium, group 2 sufentanil and atracurium, group 3 fentanyl and vecuronium, and group 4 fentanyl and atracurium. Laryngoscopy and intubation were performed 60 seconds after induction. Intraocular pressure was measured prior to induction, 30 and 60 seconds after induction, immediately after intubation, and postintubation for 5 minutes. Postinduction and postintubation intraocular pressure values in all four groups did not exceed baseline values. We conclude that in fit patients, the combination of thiopentone, moderate dose narcotics, and an appropriate dose of vecuronium or atracurium produces satisfactory conditions for intubation following rapid sequence induction without increases in intraocular pressure. This technique should not, however, be employed when multiple other injuries are present, along with an open eye.

Accelerated recovery from combined atracurium-vecuronium neuromuscular block

Patients given combinations of non-depolarizing neuromuscular blocking drugs have been reported to recover from neuromuscular block more rapidly than patients given a single drug. This study was designed to assess if this phenomenon occurred with the combination of atracurium and vecuronium. During nitrous oxide-fentanyl anaesthesia, 30 adult patients were allocated randomly to receive atracurium 0.5 mg kg-1, vecuronium 0.1 mg kg-1, or a combination of atracurium 0.125 mg kg-1 + vecuronium 0.025 mg kg-1. All patients had 100% neuromuscular block, and times to block onset did not differ significantly between the three groups. Recovery to 10, 25, 50 and 90% of control twitch height was significantly faster in the group receiving the combination of drugs.

"Defasciculation" with metocurine prevents succinylcholine-induced increases in intracranial pressure

In order to determine whether a small, "defasciculating" dose of metocurine could prevent increases in intracranial pressure (ICP) induced by succinylcholine (Sch), the authors studied 12 patients (ages 25-79 yr) undergoing craniotomy for excision of malignant supratentorial gliomas. After insertion of a subarachnoid bolt for ICP monitoring and a radial arterial cannula for determination of blood pressure and blood gas tensions, six patients (group I) were randomly allocated to receive MTC 0.03 mg/kg 3 min before induction of general anesthesia with thiopental 4 mg/kg and nitrous oxide 70% in O2. Six other patients (group II) received saline 0.015 ml/kg instead of MTC, followed by the same induction sequence. After induction of anesthesia, ventilation was controlled by mask (PaCO2 = 40 mmHg +/- 2 SE), and arterial and intracranial pressures were allowed to stabilize. Four minutes after thiopental administration (7 min after MTC), after a 1-min period of relatively stable arterial pressure and ICP, Sch 1 mg/kg was administered as a bolus. ICP and blood pressure were recorded continuously until normal twitch tension was restored. In group I (MTC pretreatment), ICP did not change significantly from the mean value observed before Sch, 14 mmHg +/- 2 SE. In group II (saline pretreatment), ICP increased from 11 mmHg +/- 2 SE to 23 mmHg +/- 4 SE (P less than .05). This study not only confirms previous work showing that Sch may induce marked ICP increases in lightly anesthetized patients with intracranial mass lesions, but also indicates that pretreatment with a "defasciculating" dose of MTC can prevent these potentially deleterious ICP increases in patients known to be at risk.

Increases in intracranial pressure from succinylcholine: prevention by prior nondepolarizing blockade

Whether succinylcholine causes an increase in intracranial pressure (ICP) in patients with brain lesions is uncertain and, if increased ICP does occur, its pathophysiology remains unknown. The authors investigated both the effect of succinylcholine on ICP and its modification with prior neuromuscular blockade by measuring ICP (subarachnoid bolt) in 13 consecutive patients with brain tumors who received succinylcholine both before and after complete neuromuscular blockade with vecuronium. Anesthesia was induced with thiopental, 6 mg X kg-1 iv, and nitrous oxide, 70% in oxygen, while ventilation was controlled (PaCO2 = 37.2 mmHg +/- 1.7 SE). Succinylcholine, 1 mg X kg-1 iv, was administered and ICP, heart rate (HR), and blood pressure (BP) were recorded until normal twitch tension was restored. Complete neuromuscular blockade was then established with vecuronium, 0.14 mg X kg-1 iv; 3 min later, succinylcholine, 1 mg X kg-1 iv, was repeated. The resulting changes in ICP, HR, and BP were recorded for 3 min. Following the first dose of succinylcholine, mean ICP increased from 15.2 mmHg +/- 1.3 SE to 20.1 mmHg +/- 2.0 SE (P less than 0.05), with five of the patients sustaining increases in ICP of 9 mmHg or greater. In contrast, when succinylcholine was given after vecuronium-induced paralysis, no patient developed an increase in ICP greater than 3 mmHg (P less than 0.05 compared with the incidence of ICP greater than or equal to 9 mmHg observed after the first dose of succinylcholine). A second group of six patients received two doses of succinylcholine according to the same protocol but without an intervening dose of vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

Atracurium, vecuronium, and intraocular pressure in humans

We studied 60 nonophthalmologic patients, allocated to six treatment groups, to assess the effects of atracurium and vecuronium on intraocular pressure (IOP). All patients had IOP measured while awake, using pneumotonometry. In group 1, anesthesia was induced with thiopental, 5 mg/kg, and maintained with N2O, 70% in O2, using controlled mask ventilation, for 5 min. These patients then received atracurium, 0.5 mg/kg. After 5 additional minutes of ventilation, the trachea was intubated. From 1 min after thiopental administration until 1 min after intubation, IOP was recorded every minute. Patients in groups 2, 3, and 4 were treated identically to those in group 1, except the muscle relaxant given was atracurium, 1.0 mg/kg, vecuronium, 0.1 mg/kg, or vecuronium, 0.2 mg/kg, respectively. Patients in groups 5 and 6 underwent rapid sequence induction with thiopental, 5 mg/kg, and atracurium, 1.0 mg/kg, or vecuronium, 0.2 mg/kg, respectively. IOP was measured 1 min later, followed by intubation and IOP measurements for the next 3 min. Intraocular pressure decreased significantly in groups 1, 2, 4, and 6 after thiopental and remained stable in all groups during ventilation with N2O. Neither atracurium nor vecuronium affected IOP, nor was there any correlation between IOP and degree of neuromuscular blockade. However, IOP increased significantly after intubation in all six groups. We conclude that atracurium or vecuronium alone has no adverse effects on IOP.

Endotracheal tube leak pressure and tracheal lumen size in swine

Endotracheal tube "leak" is often estimated in children to judge the fit of uncuffed endotracheal tubes within the trachea. Twenty-five swine were intubated with uncuffed tracheal tubes to determine whether a more sensitive measurement of leaks could be devised and whether leak pressure estimates fit between tracheal tube and trachea. We compared leak pressure measurement using a stethoscope and aneroid manometer with a technique using a microphone, pressure transducer, and recorder, and found no differences between the two methods. The tracheas were then removed and slides prepared of tracheal cross-sectional specimens. Regression analysis revealed a linear relationship between tracheal lumen size and tracheal tube size for both low leak pressure (y = -0.4 + 0.79x, r = 0.88, P less than 0.05) and high leak pressure (y = -2.9 + 0.71x, r = 0.92, P less than 0.05) groups. We conclude that leak testing with a stethoscope and aneroid manometer is sensitive and accurate, and that tracheal tube leak pressure accurately portrays fit between tube and trachea.

Serum potassium following succinylcholine in patients with brain tumours

Serum potassium levels were measured in 15 patients with brain tumours between 3-7 cm diameter, during thiopentone/70 per cent N2O in O2 anaesthesia, with mask ventilation controlled to maintain a constant end-tidal CO2 concentration. Potassium levels were determined one minute before and one and ten minutes after administration of succinylcholine 1.0 mg X kg-1 IV. No statistically significant increase in serum potassium occurred following succinylcholine, nor were there any ECG changes associated with succinylcholine administration. Use of succinylcholine in patients with brain tumours does not appear to cause elevation of serum potassium levels or ECG changes.

Lidocaine pharmacokinetics in children during general anesthesia

In spite of the increasing use of intravenous lidocaine in the operating room, no pharmacokinetic data exist for intravenous lidocaine in children. We studied ten children, ages 0.5-3 yr, and eight adults to determine lidocaine pharmacokinetics during anesthesia with halothane, nitrous oxide, and oxygen. After induction of anesthesia, tracheal intubation, and insertion of venous and arterial catheters, lidocaine, 1 mg/kg, was infused intravenously over 30 sec. Arterial samples were drawn at 0.5, 1, 2, 4, 5, 10, 15, 30, 60, 90, and 120 min. Plasma was separated and analyzed for lidocaine, using gas chromatography. Plasma concentration vs time data were fitted to a two-compartment model. Using standard formulas, we derived the following data: Children: distribution half-life (t 1/2 alpha) 3.2 min, elimination half-life (t 1/2 beta) 58 min, volume of the central compartment (V1) 0.22 L/kg, volume of distribution (Vd area) 1.1 L/kg, and total plasma clearance (Cl) 11.1 ml X kg-1 X min-1. Adults: t 1/2 alpha 3.6 min, t 1/2 beta 43 min, V1 0.16 L/kg, Vd area 0.71 L/kg, and Cl 9.8 ml X kg-1 X min-1. No significant differences were found between children and adults for all parameters analyzed. We conclude that children older than 6 months of age distribute and eliminate intravenous lidocaine in the same manner as adults.

Anaesthetic management of a child with dermatomyositis

A two years, ten months old male with dermatomyositis was anaesthetized with enflurane, nitrous oxide and oxygen by mask followed by intravenous succinylcholine to facilitate endotracheal intubation. The evoked thumb twitch in response to succinylcholine demonstrated an abnormal, short-lived contracture. The depression, duration and return to control of muscle twitch tension and a transient rise in serum potassium concentration followed a normal pattern.

Intracranial pressure after atracurium in neurosurgical patients

In order to investigate the usefulness of atracurium for neurosurgical anesthesia, we studied its impact on intracranial pressure (subarachnoid bolt) mean arterial pressure (radial artery catheter) and cerebral perfusion pressure (mean arterial pressure-intracranial pressure) in 20 patients undergoing elective craniotomy for brain tumor excision. General anesthesia was induced with thiopental, 4 mg/kg intravenously, and maintained with 70 percent nitrous oxide in oxygen. Ventilation was controlled by face mask, with end-tidal CO2 held constant. Once intracranial pressure and mean arterial pressure had stabilized, the response to atracurium, 0.5 mg/kg intravenously, was continuously recorded for 5 min in 10 patients. An additional 10 patients received no atracurium and served as matched controls. Thiopental caused reductions in ICP in both groups of patients. Comparing the responses of the patients who received atracurium with those who did not, we found that atracurium had no significant effect on intracranial pressure, mean arterial pressure or cerebral perfusion pressure. Based on these data we conclude that atracurium appears to be preferable to the other available neuromuscular blocking agents that have been evaluated for neurosurgical anesthesia.

Resolution of bronchospasm by atropine: report of a case

A case of bronchospasm during general anesthesia is presented in which atropine appeared to reverse bronchoconstriction, after high halothane concentrations, intratracheal lidocaine, and isoproterenol i.v. had all proved ineffective. This case illustrates a rational approach to the treatment of bronchospasm during anesthesia, based on determination of the most likely site of origin of bronchoconstriction within the tracheobronchial tree.

Heart block after intravenous lidocaine in an infant

A 14-day-old infant received intravenous lidocaine (2 mg X kg-1) at the conclusion of cataract surgery to prevent coughing from tracheal tube stimulation. Within 30 seconds the infant developed high-grade AV heart block and a ventricular rate of 40. Following brief resuscitation efforts, the patient had a normal cardiac rhythm, blood pressure and respiratory pattern. Intravenous lidocaine may be followed by major disturbances in cardiac rhythm and rate. Cautious titration of small doses should decrease the potential for adverse effects.

Anisocoria after anaesthesia

Unequal pupil size following anaesthesia is an unsettling finding, suggestive of acute, perioperative intracranial pathology. We report here an unusual cause of anisocoria after anaesthesia: unintended entrance of phenylephrine nasal vasoconstrictor solution into the eye.

Assessment of digital blood flow and palmar collateral circulation. Allen's test vs. photoplethysmography

Collateral circulation of the hand and digits was evaluated in 20 healthy male volunteers using a modified Allen's test and photoelectric plethysmography. A borderline (7-14 sec) Allen's test was present in 12.5% and 2.5% required more than 15 seconds for thenar flush. Photoplethysmography was then used to compare the relative contributions of ulnar artery flow to total arterial flow into the hand. This ratio, (ulnar/total) was termed the flow index (FI). Average FI for the first digit (thumb) was 0.59, and for the second digit (index) was 0.64. The FI difference between the first digit and that of the third, fourth and fifth digits was statistically significant (p less than 0.01). The FI difference between the second digit and the third, fourth and fifth digits was also statistically significant (p less than 0.05). These results imply that Allen's test may be misleading, indicating adequate collateral circulation when in fact collateral blood flow to the digits may be poor or nonexistent.

Atracurium for intubation in man. A clinical and electromyographic study

Atracurium is a new competitive neuromuscular blocking agent. We prospectively studied intubating conditions 2.5 minutes after atracurium doses of 0.4 or 0.5 mg/kg. For comparison, we evaluated conditions 1 minute after suxamethonium 1.0 mg/kg, there being 10 patients in each group. The same anaesthetist evaluated conditions during laryngoscopy and intubation in all patients. Intubating conditions were excellent in 33% of patients receiving atracurium 0.4 mg/kg and 60% of those receiving atracurium 0.5 mg/kg after 2.5 minutes; conditions were excellent in 80% of patients 1 minute after suxamethonium. The incidence of successful intubation on the first attempt was 67%, 90%, and 100%, respectively, in the three groups. Atracurium may be a suitable alternative to suxamethonium when speed of intubation is not critical.

Enflurane, halothane, and aminophylline--uptake and pharmacokinetics

This study was designed to evaluate the effects of induction of enflurane or halothane anesthesia on the distribution and elimination of previously administered intravenous aminophylline, and to evaluate the effect of previously administered intravenous aminophylline on the uptake of enflurane or halothane. Fifty-four dogs were studied: 6 received no anesthetic, 24 received enflurane, and 24 halothane. The six animals receiving no anesthetic were given 10 mg/kg of aminophylline. In each of the two groups of 24 animals, six animals served as controls and received no aminophylline. Of the other 18 animals in each group, six received 10 mg/kg of aminophylline, six received 25 mg/kg of aminophylline, and six received 50 mg/kg of aminophylline intravenously before induction of enflurane or halothane anesthesia. The redistribution (alpha) phase of theophylline was similar when anesthesia was induced with either enflurane or halothane and slightly more rapid when no anesthetic was given following aminophylline administration. The elimination (beta) phase of theophylline in the presence of either anesthetic was not significantly different than when no anesthetic was administered. The uptake of enflurane or halothane was unaffected by prior administration of aminophylline. Differences in arrhythmogenicity between enflurane and halothane after aminophylline administration are not related to alterations in theophylline pharmacokinetics or anesthetic uptake.

Lack of arrhythmogenicity of isoflurane following administration of aminophylline in dogs

Induction of halothane anesthesia after aminophylline administration may cause ventricular arrhythmias. Isoflurane may be as effective a bronchodilator as halothane. This study was designed to determine whether induction of isoflurane anesthesia after intravenous aminophylline is arrhythmogenic in dogs. One group of six dogs was anesthetized with 1.5% isoflurane in the absence of aminophylline. Three additional groups of six dogs were given intravenous aminophylline 10, 25, or 50 mg/kg, respectively, followed 3 min later by 1.5% isoflurane. No arrhythmias occurred after aminophylline and isoflurane at any time in any animal. In contrast to halothane, induction of isoflurane anesthesia after aminophylline is safe and does not cause cardiac arrhythmias.

Atracurium during halothane anesthesia in humans

The neuromuscular effects of atracurium were studied in 20 patients anesthetized with 0.8% end-tidal halothane. Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle resulting from stimulation of the ulnar nerve. Four groups of five patients received single atracurium doses of 0.1, 0.15, 0.2, or 0.4 mg/kg, respectively. The block produced by 0.1 mg/kg was 25-72% and lasted 6-21 min. The block produced by 0.15 mg/kg was 69-93% and lasted 16-32 min. The blocks produced by 0.2 and 0.4 mg/kg were 95% or greater and lasted 42-84 min and 55-104 min, respectively. When indicated, intubation was easily performed in all patients receiving 0.2 and 0.4 mg/kg. The block could be readily antagonized by neostigmine and atropine. Changes in heart rate and blood pressure following atracurium administration averaged less than 5%.

"Liquid stylet" for percutaneous radial artery cannulation

Radial artery catheterization in elderly patients may be difficult. The "liquid stylet" created by slow intra-arterial fluid injection facilitates insertion of arterial cannulae, and proved effective in 14 consecutive patients in whom percutaneous radial artery catheterization was otherwise unsuccessful. This technique is useful when difficulty in radial artery cannulation is encountered.

Cardiovascular effects of ketamine following administration of aminophylline in dogs

The induction of halothane anesthesia following intravenous administration of aminophylline may cause ventricular arrhythmias. Ketamine has been recommended for anesthesia induction and maintenance in patients with asthma. This study was designed to determine whether induction and maintenance of ketamine anesthesia following intravenous aminophylline is arrhythmogenic in dogs. One group of six dogs was anesthetized with intravenous ketamine, 5 mg/kg, followed by infusion of 5 mg/kg/hr. Three additional groups of six dogs were given intravenous aminophylline, 10, 25, and 50 mg/kg, respectively, followed 3 minutes later by intravenous ketamine, 5 mg/kg, and a 5 mg/kg/hr ketamine infusion. No arrhythmias occurred at any time in any animal. Ketamine use following aminophylline would appear to lack arrhythmogenic potential and may be advantageous in the clinical setting.

Safety of enflurane following administration of aminophylline in experimental animals

The induction of halothane anesthesia following intravenous administration of aminophylline may cause ventricular arrhythmias. This study was designed to determine whether induction of enflurane anesthesia following intravenous aminophylline is arrhythmogenic in dogs. One group of six dogs was anesthetized with 2% enflurane in the absence of aminophylline. Three additional groups of six dogs were given intravenous aminophylline, 10, 25, or 50 mg/kg, respectively, followed 3 minutes later by 2% enflurane. No arrhythmias occurred at any time in any animal. In contrast to halothane induction of enflurane anesthesia following aminophylline appears to be safe and does not cause cardiac arrhythmias.

Halothane-induced cardiac arrhythmias following administration of aminophylline in experimental animals

Cardiac arrhythmias often occur when patients receiving aminophylline are anesthetized with halothane. This animal study was designed to define what constitute arrhythmogenic doses of aminophylline when administered before halothane anesthesia. One group of six dogs was given aminophylline, 10 mg/kg IV, followed in 3 minutes by inhalation of 1% halothane. In two additional groups of dogs the same experimental protocols were used except that aminophylline doses were 25 mg/kg and 50 mg/kg. In the first group, two of six dogs developed ventricular arrhythmias during induction of halothane anesthesia. One of six dogs given 25 mg/kg of aminophylline developed a ventricular arrhythmia. Three of six dogs given 50 mg/kg of aminophylline developed ventricular arrhythmias. Sustained ventricular arrhythmias occurred in 33% of the animals with "therapeutic" serum theophylline levels and in 33% of the animals with "toxic" levels. Induction of halothane anesthesia within 15 minutes of aminophylline administration may be dangerous and is likely to result in severe and persistent ventricular arrhythmias.

Circle system failure induced by gastric suction

Blind passage of a nasogastric suction catheter during anaesthesia resulted in sudden inability to ventilate the patient. Passage of the catheter into the trachea was diagnosed and ventilation restored following catheter removal. Misdiagnosis of this situation can result in potentially disastrous attempted remedies.

Sodium nitroprusside-induced hypotension in radical thoraco-abdominal dissection of retroperitoneal lymph nodes

Blood loss and replacement in 57 consecutive otherwise healthy young patients undergoing radical thoraco-abdominal dissection of retroperitoneal lymph nodes is reviewed. Twenty-five patients received nitroprusside (hypotensive group); 32 patients (normotensive group) did not. Blood loss varied significantly between the hypotensive and normotensive groups: the mean loss (+/- SEM) was 920 +/- 72 ml for the hypotensive group compared with 1341 +/- 98 ml for the normotensive group (P < 0.001). The total blood requirement for the normotensive patients was three times that of the hypotensive group. The difference between the two groups was more apparent in patients with advanced disease.