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September 1999
Volume 63 |
Number 9
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| Curtis L. Mendelson,
M.D.: Aspiration Investigator (1913- ) |
Paul R. Knight, M.D.,
Ph.D.
Most anesthesiologists are well acquainted with Mendelson's syndrome.
Curtis L. Mendelson, M.D., is best recognized as the physician
who described the symptom complex associated with gastric acid
aspiration. He clearly established the role of the low pH property
of gastric secretions as an important mechanism involved in the
pathogenesis of the lung injury. Dr. Mendelson was a Professor
of Obstetrics and Gynecology at Cornell School of Medicine, not
an anesthesiologist. Yet, a number of his scholarly observations
regarding this important perioperative respiratory complication
as well as his recommendations of prevention and care dramatically
impacted the perioperative practices of anesthesiologists. However,
his role in influencing the development of the practice and specialty
of anesthesiology is not well appreciated. Thus, it is worthwhile
to revisit some of Dr. Mendelson's achievements from the perspective
of the evolution of anesthesia care.
Aggressive protection of the airway is a major principle
in providing anesthesia care. However, this practice has not always
been performed as fastidiously as is done currently. Furthermore,
despite improvements in the prevention of this feared complication,
aspiration of gastric contents still remains a significant problem
in patients during induction and emergence from anesthesia. Gastric
aspiration may also occur in the patient who, for example, has
lost consciousness prior to coming to the operating theater, as
can occur with trauma. Additionally, although loss of control
of airway reflexes secondary to altered consciousness is the major
proximal cause, there is also a considerable problem with passive
regurgitation of stomach contents in the geriatric patient population
during normal sleep.
Aspiration of gastric contents occurs in approximately
1 in 3,000 anesthetics. "Silent" aspiration of stomach contents
can be implicated in the etiology of a number of unexplained cases
of postoperative pulmonary dysfunction. Aspiration of gastric
contents may result in a spectrum of lung injuries from a very
mild, sub-clinical pneumonia to a more severe, progressive disease
such as adult respiratory distress syndrome (ARDS), with a very
high associated morbidity and mortality. Aspiration pneumonitis
also predisposes the patient to the development of a subsequent
bacterial pulmonary infection. It has been reported that approximately
one-third of patients with acute aspiration pneumonia will develop
a more severe, protracted course with secondary complications.
Aspiration pneumonitis carries a 30-percent mortality and accounts
for up to 20 percent of all deaths attributable to anesthesia.
Thus, the threat of gastric aspiration plays an important role
in planning the anesthetic strategy and, as such, is important
in determining how to protect the airway during anesthesia. The
principal of protecting the airway forms one of the corner stones
of the practice of anesthesiology.
Historically, the deleterious effects of aspiration of
food and drink had been known since the time of Hippocrates. John
Hunter performed the first scientific experiments investigating
the pathophysiology of aspiration in 1781. The first documented
death related to anesthesia was most likely a result of the liquid
administered during unconsciousness. In this case, Sir James Simpson
identified pulmonary aspiration of the brandy and water that Hannah
Greener, a 15-year-old girl, was given during chloroform anesthesia
since "her lips, which had been previously of good color, became
suddenly blanched, and sputtered slightly at the mouth as one
with epilepsy." Additionally, case reports on gastric aspiration
from several series of patients had previously been reported by
a number of Dr. Mendelson's obstetrical colleagues.
So why then did gastric acid aspiration become known as
Mendelson's syndrome? In 1946, Curtis Mendelson became the first
investigator to rigorously study the pathogenesis of the disease
using both patient case reports and experimental animals. He was
able to demonstrate that the hydrogen ion concentration was critical
to the development of the clinical picture and pathology seen
following aspiration of the gastric contents. Additionally, the
animal component of Mendelson's research in this seminal article
was so well conceived that today many investigators use similar
procedures to model gastric aspiration in the laboratory. Dr.
Mendelson could certainly be considered as one of the first physician-scientists
to perform translational research.
Dr. Mendelson clearly described the pathogenic changes
that occurred as a result of gastric aspiration as well as the
clinical symptoms. Based on these findings, recommendations for
prevention and treatment of aspiration of gastric contents that
are still practiced in obstetrical anesthesia as well as all surgical
patients were proposed. For example, in order to decrease the
incidence of this complication, Mendelson recommended first "withholding
oral feedings during labor and substituting parental administration,"
secondly "wider use of local anesthesia ... where feasible" and
thirdly "alkalization of and emptying the stomach." He also prescribed
the supportive therapy regime that still comprises the primary
treatment modality that we currently offer these patients. These
principles of practice were presented a number of years before
Brian A. Sellick, M.B., recommended prophylactic approaches
to prevent aspiration of gastric contents in the patient with
a full stomach.
Dr. Mendelson argued quite aggressively for better-trained
personnel in the administration of anesthesia to his patients.
He clearly was not happy regarding the poor, inexperienced anesthesia
support his specialty was receiving at this time and suggested
methods by which obstetricians could overcome this problem. In
the discussion section of his 1946 article, Mendelson stated,
"The anesthetic deserves special consideration." He further goes
on to address several important issues in the anesthetic care
of the obstetrical patient, suggesting that local anesthesia would
eliminate the dangers of "incompetently administered general anesthesia."
Dr. Mendelson also listed several important skills in airway management
in which he believed that individuals administering an anesthetic
should become proficient (e.g., skill in laryngoscopy).
The lively debate that followed the presentation of Dr.
Mendelson's findings primarily involved the discussion of the
need for an anesthesiologist-run service responsible for respiratory
management oversight. One of the discussants stated, "We feel
very strongly for the necessity for having a well-coordinated,
physician-controlled anesthesia department which is in control
of all pneumatologic and transfusion services." Thus, the presentation
of this work was a significant event in promoting the importance
of the specialty of anesthesiology. Clearly, the physicians present
at this discussion believed that an independent, physician-run
hospital-based department was critical for delivering optimal
care for the obstetrical patient population. Additionally, the
importance of the anesthesiologist in decreasing the incidence
of this complication was emphasized. For example, one of the discussants
bemoaned the fact "that there is no anesthetist on this program
as it is largely an anesthetic problem." The resultant discussion
that occurred during the meeting portion of the presentation of
this work generated a statement of principles that could not but
help promote the development of anesthesiology as a specialty.
However, Dr. Mendelson's work was not entirely salutary
to our understanding of the pathogenesis of gastric aspiration.
Mendelson's syndrome became synonymous with gastric acid aspiration.
However, his experiments examined both acid and particulate aspiration.
He carefully described both clinical entities, and his animal
studies also assessed the pathologic picture following experimental
installation of intratracheal acid, particulate and acidified-particulate
material solutions. Mendelson dismissed the effects of the presence
of particulate material in the vomitus as being a problem primarily
of airway obstruction and not inflammation. As a result of these
experiments, the medical community and anesthesiologists in particular,
focused on the pH of the vomitus as being a critical factor in
assessing the risk as to whether aspiration of gastric contents
would develop into a severe pneumonitis. However, a combined acidic
food particle aspiration results in a synergistic inflammatory
lung injury. Furthermore, gastric aspiration is now well-recognized
as a major risk factor in the pathogenesis of adult respiratory
distress syndrome, and the presence of particulate material in
the vomitus is associated with a greater likelihood that the initial
pulmonary insult will develop into the more severe progressive
lung injury. The lack of investigation for many years following
Mendelson's report into the role of constituents of gastric contents
in the pathogenesis of lung injury following aspiration, other
than the hydrogen ion concentration, illustrates the major impact
Mendelson's work has had on the anesthesiology community.
In conclusion, Curtis L. Mendelson, M.D., was a physician-scientist
of considerable stature in the practice of obstetrics and gynecology.
Although not an anesthesiologist, he strongly influenced the principles
of practice and
development of our specialty. Mendelson's report on aspi-
ration of stomach contents by obstetrical patients undergoing
anesthesia was very comprehensive in its description of
both the clinical and pathologic picture of the lung injury. Because
of this clinical account and his compelling animal studies on
the etiologic cause of the pathogenesis of the pneumonitis, the
pulmonary symptoms following gastric acid aspiration have since
been known as Mendelson's syndrome, a result that has led anesthesiologists
to focus, until recently, on the pH of the vomitus when aspiration
occurs.
Dr. Mendelson's work reinforced the need for protective
airway management practices (e.g., mandatory use of suction and
skill in laryngoscopy) during the evolution of our specialty.
Because of his view on the critical nature of airway management
in the support of the obstetrical service as well as his ability
to influence his obstetrical colleagues in this regard, anesthesiology
became a strong driving force and developed as an important specialty.
His work fostered the concept by his obstetrical colleagues that
individuals who practice anesthesia should be proficient in important
skills and belong to a distinct hospital-based clinical department.
It is for these reasons that Dr. Mendelson deserves recognition
as one of the key individuals involved in the development of principles
and practices of anesthesia care, particularly in regard to airway
management associated with the evolution of the specialty.
References available on request from the author and on the
ASA Web site.
Paul R. Knight, M.D., Ph.D., is Professor
of Anesthesiology and Microbiology and Vice Chair for Research
in Anesthesiology, State University of New York at Buffalo School
of Medicine, Buffalo, New York.
References:
- Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary
aspiration during the perioperative period. Anesthesiology.
1993; 78(1):56-62.
- Tunstall ME, Ostheimer GW. Obstetrics. In: Nunn JF, Utting
JE, Brown BR. Eds. General Anesthesia. London: Butterworth and
Co.; 1989:988-1008.
- Britto J, Demling RH. Aspiration lung injury. New Horiz.
1993; 1(3):435-439.
- Bodlander FM. Deaths associated with anaesthesia. Br J Anaesth.
1975; 47(1): 36-40.
- Gardner AM. Aspiration of food and vomit. Q J Med. 1958;
27:227-242.
- Simpson JY. Remarks on the alleged case of death from the
action of chloroform. Lancet. 1848; 1:175.
- Mendelson CL. The aspiration of stomach contents into the
lungs during obstetric anesthesia. Am J Obstet Gynecol. 1946;52:191-205.
- Knight PR, et al. Pathogenesis of gastric particulate lung
injury: A comparison and interaction with acidic pneumonitis.
Anesth Analg. 1993;77:754-760.
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