Robert C. Morell

Dilutional acidosis: is it a real clinical entity?

Dilutional acidosis occurs as a result of rapid extracellular volume expansion decreasing the measured serum bicarbonate. This phenomenon is not well described in the literature. Searching the English medical literature, we found only one case report of dilutional acidosis 1 and no case reports of dilutional acidosis occurring within the perioperative period. Several authors have concluded that dilutional acidosis has little actual clinical significance because of cellular buffering in which rapid extracellular volume expansion caused only minimal changes in measured extracellular bicarbonate and pH levels. 2-4 We report a case of dilutional acidosis occuring intraoperatively as a direct result of giving a large volume of isotonic saline.

Tracheal intubation of healthy pediatric patients without muscle relaxant: a survey of technique utilization and perceptions of safety.

We conducted a survey of Society for Pediatric Anesthesia anesthesiologists practicing within the United States to determine the frequency of tracheal intubation of healthy infants and children using an inhaled anesthetic without muscle relaxation (IAWMR).We also examined reasons for the use of this technique. Of all responders who listed their most often used technique for tracheal intubation of healthy infants and children, IAWMR was chosen over intubation with a muscle relaxant by 38.1% and 43.6%, respectively. Anesthesiologists who most often used IAWMR for tracheal intubation of healthy infants and children had over twice the odds (odds ratio [OR] 2.30 for infants, 95% confidence interval [CI] 1.18-4.50; P = 0.015) of classifying their own practice as nonacademic, and one-third the odds (OR 0.34 for infants, 95% CI 0.17-0.68; P = 0.002) of conducting more than half of their cases in a supervisory role. Anesthesiologists who use IAWMR to tracheally intubate healthy pediatric patients most commonly selected as their reasons the lack of need for a muscle relaxant and the desire to avoid both succinylcholine and the excessive duration of nondepolarizing muscle relaxants. Implications: Inhaled anesthetic without muscle relaxation is the most often used method of intubation for more than one third of Society for Pediatric Anesthesia anesthesiologists when tracheally intubating healthy, fasted pediatric patients undergoing elective procedures. The frequency of this practice seems to be highest in nonacademic practices. (Anesth Analg 1999;88:737-41)

The Future of Anesthesiology: Should the Perioperative Surgical Home Redefine Us?

Anesthesiology is at a crossroads. The “Burning Platform” allegory highlights the dilemma facing clinical care and anesthesiology today. We are the workers trapped 150 feet above a stormy, cold ocean on a burning oil platform.a Balanced on that burning stage, our options are limited. None are attractive. For the oil rig worker, death is certain if he stays, and almost certain if he jumps. This metaphor emphasizes that in the face of uncertainty about the future, radical action is required of all of us. This analogy is particularly relevant to the practice of medicine in an unsustainable and rapidly evolving health care environment. Survival instincts (e.g., jumping 150 feet into icy water) trumps one’s instinct to hesitate and hope the current situation fades. For years, the flames of change have been nipping at the heels of the medical practice of anesthesiology. Some think we are “crying wolf.” But most health care experts and even the lay public acknowledge that we must change how we approach our patients and practice. We must adapt to new models of care. We must address some of the most vexing problems that compromise the patient-provider relationship and its impact on quality, safety, and health outcomes. As Dr. Karen Domino opined in her 2014 American Society of Anesthesiologists (ASA) Rovenstine Lecture, “This is no time for business as usual. The forces driving change are enormous, but they can be guided. The clock is ticking. The time to act is now.”

Men are more susceptible than women to direct pressure on unmyelinated ulnar nerve fibers.

Ulnar nerve injury, the most common form of perioperative peripheral nerve injury, has a 3:1 male/female predominance. Neither the mechanism of perioperative ulnar nerve injury nor the reasons for the increased male susceptibility are well understood. We used an experimental model with arm flexion at the elbow, direct pressure on the ulnar nerve, and arm ischemia as distinct stress mechanisms to induce adverse changes in ulnar current perception thresholds (CPTs) on 3 groups of 40 male and 40 female volunteers (a total of 240 volunteers). CPT measurements were repeated at 2000-, 250-, and 5-Hz stimulating frequencies, specific to A-&bgr;, A-&dgr;, and unmyelinated C-fibers, respectively. Ischemia produced significant increases in CPT with all three stimulating frequencies, and there were no detectable differences between men and women. Flexion failed to produce significant CPT increases at any of the three stimulating frequencies, with no sex-based differences. Direct pressure produced significant CPT increases at 5 and 250 Hz, indicating inhibition of both unmyelinated C-fibers and myelinated A-&dgr; fibers. C-fibers, but not A-&dgr; fibers, demonstrated sex differences with direct pressure; there was a 1.7-fold (95% confidence interval, 1.2- to 2.4-fold) greater effect in men. Ischemia significantly inhibited the function of all three fiber types, perhaps sufficient to overwhelm gender differences.

Fluoroscopy-assisted intubation of a child with an unstable subluxation of C1/C2.

Patients presenting with unstable cervical spine injuries are at risk for additional neurological injury as a consequence of airway manipulation. Techniques of awake intubation may not always be desirable or practical, particularly in the pediatric patient. We describe the use of fluoroscopy during the induction of anesthesia and intubation of a child with an unstable C1/C2 spinal subluxation. Fluoroscopy is readily available and noninvasive. This technique allows for rapid establishment and maintenance of optimal head and neck positioning during induction of general anesthesia and performance of laryngoscopy and tracheal intubation.

FDA group urges sux label reduced to "warning".

Adoption of a drug label statement that succinylcholine is contraindicated in pediatric patients provoked a great deal of discussion, including an extensive debate and editorial in the Spring 1994 A P S F Newsletter. Subsequent events have led to a strong recommendation that this contraindication be downgraded to a warning. Outlined here is the chronology of the involved events, revealing to the anesthesiology community for the first time the process by which drug labeling, particularly involving perceived hazards, occurs.

In my opinion: a debate ― can succinylcholine be used routinely with safety in children?

No, succinylcholine should be used only when the clinician deems it necessary to have a relaxant with a rapid onset and short duration, because the many side effects range from troublesome to life-threatening. The well-documented, undesirable side effects ofsuccinylcholine include muscle pain, cardiovascular changes, arrhythmias and cardiac arrest, increases in intraocular and intragastric pressure, masseter spasm, myoglobinemia, myoglobinuria, association with malignant hyperthermia (MH), and hyperkalemia in susceptible patients. The risk of hyperkalemia has been highlighted recently with case reports of patients with unsuspected muscle disorders, primarily Duchennes muscular dystrophy. It is for this reason that the FDA Anesthetic and Life Support Drugs Advisory Committee and the Pilot Drug review team, along with the four manufacturers of succinylcholine, have recently stated that succinylcholine is contraindicated for routine use in children and adolescents, except for emergency tracheal intubation or in instances where immediate securing of the airway is necessary. In children, the incidence of relatively minor and easily treatable side effects, such as bradycardia, muscle pain, and increase in intraocular or intragastric pressure, is high. We have modified our practice habits because of the common occurrence of many of these side effects. For example, we routinely administer atropine when we use succinylcholine. Also, patients may be pretreated with a nondepolarizing neuromuscular blocking drug in the hope of preventing muscle fasciculations and muscle pain. The increase in intraocular pressure may be attenuated with intravenous or inhalational anesthetic agents prior to administration of succinylcholine. If we are concerned about the increase in intragastric pressure and the risk of regurgitation and aspiration, then we apply cricoid pressure until the trachea is intubated. We adapt our method of anesthesia practice to avoid the side effects of the drugs we choose to administer.