Complications of endotracheal intubation.

Tracheal intubation for airway control, once done only by anesthesiologists during surgical procedures, is now being done by physicians in other specialties and by nurses, technicians, and paramedics in areas other than the operating room. Intubation, however, does not always assure a patent airway. Unrecognized esophageal placement of endotracheal tubes is the major cause of cardiac arrest and brain damage associated with intubation. Though auscultation for breath sounds is the universally accepted method of verifying proper tube placement, recent studies indicate that it is reliable only approximately two thirds of the time in situations in which verification of proper placement is needed most and is least obvious. The usefulness of this technique merits reassessment. Identification of carbon dioxide in end-expired air is the most reliable method for verification, but instruments to detect carbon dioxide are usually immediately available only in special care and surgical suites. Mouth-to-tube insufflation with a two-way disposable microbial filter differentiates immediately between esophageal and tracheal placement and can be used in any area. Malpositioned and malfunctioning tubes cause partial or complete obstruction accompanied by varying degrees of hypoxemia and hypercapnia. Respiratory and circulatory derangements and brain damage ensue if the problem is not promptly recognized and corrected. We discuss the most common causes of tube malfunction.

Unrecognized esophageal placement of endotracheal tubes.

Unrecognized esophageal placement of endotracheal tubes during general anesthesia or in apneic unanesthetized patients is not an uncommon occurrence. Allowing this mishap to proceed to asphyxia and catastrophe is inexcusable. If one is uncertain, proper placement can be quickly verified by mouth-to-tube insufflation of a subject's lungs with one's own expired air immediately after intubation. This method of verification may be useful in areas other than the operating room, where intubations are performed for resuscitation or airway control.

Paraplegia associated with epidural anesthesia.

Spinal anesthesia has lost its popularity among physicians due to rare occurrences of paraplegia that have precipitated lawsuits, with staggering judgments in favor of claimants. Epidural block has now become a popular alternative because some believe it cannot cause paraplegia; however, paraplegia is as prevalent after induction of epidural anesthesia as after spinal anesthesia. Arachnoiditis has been incriminated as the causative agent when paraplegia has followed spinal anesthesia. Arachnoiditis is also a causative factor when paraplegia follows epidural block. Cord compression and anterior spinal artery syndrome have also been associated with paraplegia after epidural block though they have not been a problem with spinal block.

Malignant hyperthermia in dental patients.

Malignant hyperthermia is a hypermetabolic, frequently fatal syndrome triggered by anesthetic drugs that occurs in genetically susceptible persons. Fatalities have been reported in patients receiving dental treatment with general anesthesia. The syndrome may also be triggered by stress, exercise, muscle injury, mild infections, and other nonpharmacologic agents or stimuli in conscious patients. Treatment is symptomatic and empiric, and potential reactors are not easily identified. However, criteria for identifying most susceptible persons have been established, and therapeutic agents for prophylaxis and treatment, which appear to be effective, are available. In this paper we report experiences with the syndrome and discuss an overview of its features, criteria used for identifying susceptible persons, prophylaxis, diagnostic features, and procedures to be followed should the syndrome develop.

Anxiolytic effects of low dosage nitrous oxide-oxygen mixtures administered continuously in apprehensive subjects.

We observed the effect of low doses of nitrous oxide on the cardiovascular and respiratory systems, the cortisol output in blood and saliva, and the degree of sedation and analgesia of 20 volunteers. A psychologic screening inventory was also performed. We found nitrous oxide, at low dosage, to be primarily an anxiolytic and not an analgesic or amnesic agent. The nasally inhaled concentrations necessary to induce an anxiolytic effect varied from subject to subject, ranging from 30% to 65% and averaging 35% to 40%. This finding justifies the use of the gas to relieve anxiety instead of nonvolatile parenterally administered psychosedatives and narcotics. Nitrous oxide is preferable because its action is established within several minutes, it is rapidly eliminated at the conclusion of a procedure, and the sensorium is clear after five or six minutes. The gas is simply and safely administered with fail-safe apparatus designed specifically for this purpose. The technic is admirably suited for use in ambulatory care units where minor surgical or dental procedures are performed.

Allergic reactions to local anesthetics.

The majority of adverse reactions to local anesthetics are due to high plasma levels from excessive quantities of a drug. These are often blamed on idiosyncrasy, sensitivity, or allergy. The incidence of reactions due to allergy to local anesthetics is low compared to that with other drugs. Allergic reactions may be systemic or local. More than 80% of reactions are cell mediated, resulting in contact dermatitis. The remainder are caused by circulating antibodies that give rise to systemic anaphylaxis. Acute anaphylactic reactions are rare but invariably fatal unless promptly treated. Localized systemic anaphylactic reactions manifested by urticaria, laryngeal edema, and extrinsic asthma are less serious and amenable to treatment. There is no foolproof test for screening of susceptible persons. The intradermal test is of no value for detecting possible systemic sensitivity. The patch test is useful for detecting contact allergy. Systemic reactions are treated with epinephrine, antihistamines, and steroids. Contact dermatitis responds to topical steroids.

Adverse effects of pancuronium in patients with hemorrhagic shock.

Thirty-five patients with hemorrhagic shock had surgical repair of trauma to the great vessels using a ketamine-pancuronium-nitrous oxide sequence for anesthesia. The data of the cardiovascular and respiratory changes occurring during anesthesia and the operation were tabulated and subjected to multifactorial computer analysis. Fifteen patients died during or after operation because the injury was beyond repair. Twenty survived the oepration. Profound hypotension associated with mild tachycardia occurred with surprising regularity each time incremental doses of pancuronium were administered in nearly all patients. This hypotension was not associated with the administration of any other drug or with any other parameter and strongly implicates pancuronium as the causative factor. Pancuronium should be used cautiously and administered in small increments to this type of patient if it is used as a muscle relaxant.

Complications from unrecognized defects in endotracheal tubes.

Considerable effort has been made to improve endotracheal tubes and make them safer than they have been in the past; yet complications continue to occur, due, in most instances, to inherent defects in the tube. It is not possible to identify these defects in a routine preoperative examination. Three cases are presented illustrating how defects in anode endotracheal tubes almost caused fatalities during anesthesia. Other possible complications and contributing factors causing obstruction of endotracheal tubes are also reviewed. Until some way is devised for the automatic compensation of the increases in volumes and pressures in endotracheal tube cuffs, hourly deflation is recommended to prevent complications.

Acute systemic toxicity from bupivacaine during epidural anesthesia in obstetric patients.

Convulsions occurred within 30 seconds after the injection of bupivacaine through the epidural catheter in four obstetric patients in labor, and mild excitation without convulsions occurred in three others. Since the time between injection and the reaction was so short and since the dose was so small, the response probably was due to intravenous injection resulting from lodgement of the catheter in a vein, rather than to absorption from the epidural space itself. It is not generally known that the epidural veins become thin-walled and engorged during labor; thus, inadvertent placement of a cathether in a vein can occur readily. Convulsions, therefore, may follow even injection of a test dose of a drug. Other colleagues have had similar though unreported experiences. Physicians performing epidural blocks should be aware that such an occurrence is possible and that the catheter may be within a vein without blood returning on aspiration.