the history of anesthesia

8/3/2019 The History of Anesthesia

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The History of Anesthesia



O2 and CO2

In order to understand anesthesia. We need to understand where itstarted.

Although volatile and gaseous anesthetics have changed over thepast 150 years, there are two gases that will always be a part of anesthetic practice: oxygen and Carbon Dioxide.

Because of the importance that carbon dioxide and oxygen have inthe practice of anesthesiology, it is worthwhile to consider how ourunderstanding of respiration came about.

How oxygen and carbon dioxide are consumed and produced andhow they interact with the body has been the subject of intense

research over the past 400 years. Because of the importance that carbon dioxide and oxygen have in

the practice of anesthesiology, it is worthwhile to consider how ourunderstanding of respiration came about.



Hx of Respiration

Galen and Aristotle (384-322 BC) ± Thought that the air moving in and out of the lungs served merely to cool the

heart, which otherwise became overheated in working to sustain life.

Robert Hook (1635-1703)

± Attached a bellows to the trachea of a dog with an open chest and

demonstrated that the animal could be kept alive by rhythmic and sustainedcontraction of the bellows.

± He proved that movement of the chest wall was not the essential feature of respiration, but rather it was exposure of fresh air to the blood circulatingthrough the lungs.

Richard Lower (1631-1691) ± Who was also the first to transfuse blood from one animal to another

± Demonstrated in 1669 that the blood absorbed a definite chemical substancenecessary for life, that it changed the venous blood from dark blue to red, andthat the process was the chief function of the pulmonary circulation.



Phlogiston Theory

The nature of the process of respiration was misunderstood until the 1780sbecause of the generally accepted, but erroneous, phlogiston theory promoted byGeorg Ernst Stahl (1660-1734).

Stahl theorized that combustible substances were composed of phlogiston (Greekfor burnt ash) and that the phlogiston was released during burning andrespiration.

Joseph Priestley (1733-1804) ± A complex individual who was a dissenting minister in Leeds, England, observed that

respiration and combustion had many similarities, because a candle flame would go outand an animal would die if left within a closed space.

He thought this was because the air was putrefied with phlogiston.

± Priestley discovered photosynthesis by showing that placing plants in confined spacescould remove the phlogiston and purify the air.

±

By heating mercuric oxide, he generated a gas that could make flames brighter and keepmice alive longer in a closed space.

± Priestley thought this process absorbed phlogiston and informed the French chemistAntoine-Laurent Lavoisier (1743-1794) of his discovery.



Oxygen

Lavoisier realized that heating mercuric oxide

released a new element and called it oxygen.

Lavoisiers greatest contribution was to outline the

great facts of respiration: absorption of oxygen

through the lungs with liberation of carbon dioxide.

He, however, thought respiration/metabolism was

accomplished in the lungs.



But, Humphry Davy (1778-1829), a young Englishteenager who dropped out of school at the age of 16, read the works of Lavoisier and designed his ownexperiments to study the site of metabolism. ± He heated blood and collected the gases that were

produced. By showing that these gases were oxygen and carbon dioxide, he

surmised that metabolism takes place in the tissues. A conclusionconfirmed by Wilhelm Pfluger (1829-1910) 60 years later.

Davy also estimated the rates of oxygen consumption and carbondioxide production, and he measured the total lung and residualvolumes.



Advances with Oxygen

John S. Haldane (1860-1936) ± was a pioneer investigator in the study of respiration.

± He was the first to promote oxygen therapy for respiratory disease.

± In 1905, he discovered that the carbon dioxide tension for blood wasthe normal stimulus for respiratory drive.

Carl Gustav von Hufner (1840-1908) ± Showed that the presence of Hemoglobin in the blood greatly

enhanced its oxygen carrying capacity, quantifying that 1g of hemoglobin carried 1.34 mL of oxygen.

Leland C. Clark (1918-)

± Developed the oxygen electrode 1956. The electrode made it capable to calculate the gradients for inspired,

alveolar, and arterial oxygen partial pressures.



Polio Epidemic

Further understanding of respiratoryphysiology arose because of the worldwidepolio epidemic that occurred roughly between

the years of 1930-1960. Thousands of afflicted patients were kept alive

with mechanical respirators, but the adequacyof ventilation could not be assesed withoutsome measure of carbon dioxide tension inthe blood.



The problem was solved in 1958, when John W.Severinghaus (1922-) improved the accuracy of aprototype carbon dioxide electrode produced byRichard Stow (1916-).

Severinghaus and A.F. Bradley (1932-) constructedthe first blood gas apparatus by mounting theCarbon dioxide electrode and Clarks oxygenelectrode in cuvettes in a 37 degree bath. A pHelectrode was added in 1959.

Blood gas analysis made possible the rapidassessment of respiratory exchange and acid-basebalance.



The Pulse-Ox

Until the mid-20th century, the saturation of hemoglobin could bedetermined only by directly measuring a sample of arterial blood, atechnique that required an arterial puncture.

Oximetry achieves the same measure noninvasively through a finger orear probe by using optical measures of transmitted light.

Glenn Millikan, devised the first ear oximeter in 1942, and it was used todetect hypoxia in pilots, who flew in open cockpits during World War II.

Its introduction into anesthesia practice was delayed until the discovery of pulse oximetry by a Japanese engineer, Takuo Aoyagi.

Pulse Oximetry added the additional measure of heart rate, and itprovided assurance that the signal was actually measuring a biologic

parameter. A highly successful commercial product, the Nellcor pulse oximeter, was

introduced in 1983 and had the unique feature of lowering the pitch of thepulse tone as the saturation dropped.



Intravascular Pressures

The first measurement of blood pressure was made by Stephen Hales

(1677-1761)

± He fixed a brass pipe to the carotid artery of a mare and noticed that

the blood rose in the tube. Then he bleed the mare, and recognized

that the height of blood in the tube decreased. ± He also discovered that the resistance of a vascular bed would change

by mixing alcohol in the blood.

Jean L. Poiseuille (1799-1869)

± In 1828, he repeated these experiments and devised a

hemomanometer that used mercury instead of the long blood-filledtubes used by Hales.

± He also showed that the blood pressure varied with respiration.



The Sphygmomanometer

Karl Vierrordt (1818-1884)

± Invented a sphygmograph in 1854, acting on the principle that indirectestimation of blood pressure could be accomplished by measuring thecounter pressure necessary to obliterate the arterial pulsation.

Scipione Riva Rocci (1863-1937)

± Invented a sphygmomanometer in 1896, using Vierrordts same principlebut used a rubber cuff that occluded a major arterial vessel and thenslowly deflated

Nikolai Korotkov (1874-1920)

± Described the sounds produced during auscultation over a distal portionof the artery as the cuff was deflated.

±

Korotkov sounds resulted in more accurate determinations of systolic anddiastolic pressures.

Automatic blood pressure devices based on the oscillometric methoddescribed by H. von Recklinghausen in 1931, were developed in the 1970sand have become the standard noninvasive measures of arterial pressures.



Central Venous Pressure

Venous pressures were of less interest to

anesthesiologists until convenient methods

for placing cannulas into central vascular

structures were described 50 years ago by

Sven Seldinger.

The introduction of plastic catheters gradually

made it possible to measure central pressuresin the clinical setting.



PA Catheterization

Pulmonary artery catheterization with a ballon-

tipped, flow directed catheter was described in 1970

and has been used extensively since to measure

cardiac outputs using the Fick principle andpulmonary wedge pressures.

The pulmonary artery catheter also allowed the

clinician to use the well-known pressure-volume

relationships of the heart described by Ernest H.

Starling (1866-1927) in 1918 to maximize cardiac

outputs and oxygen delivery to the tissues.



TEE

Transesophogeal Echocardiography was

described in 1976 and used in anesthesia practice

a few years later.

With experience and training in TEE, the

anesthesiologist can quickly evaluate filling

pressures of the heart as well as obtain measures

of myocardial contractility and valvular function. TEE has become a routine monitor for certain

surgical procedures.



Autonomic Nervous System

Even though the first practitioners of anesthesia had

essentially no knowledge of adrenergic or cholinergic

transmission, it would be difficult to administer

anesthetics today without a thorough understandingof the ANS and its neurotransmitters.

Many modern surgical and neurovascular techniques

require strict control of arterial and venous

pressures, and this control is performed through

interventions that alter autonomic tone.



The early days

Robert Whytt (1714-1766) ± The first to describe the reflex nature of many involuntary activities.

Thomas Willis (1621-1675) ± Described the sympathetic chain as early as 1657.

± He called it the intercostal nerve because it received segmental branches from

the spinal cord at each level. Pourfour du Petit (1664-1741)

± Observed that there was a corresponding miosis when this nerve wasunilaterally cut in the neck of the cat.

Winslow

± Gave the intercostal nerve the name of grand sympathique, stressing that this

nerve brought the various organs of the body into sympathy (greek symtogether, pathos feeling)

Claude Bernard (1813-1878)

± Observed vasoconstriction and pupillary dilation that followed stimulation of the same intercostal (now called the sympathetic) nerve.



John N. Langley

Langley (1852-1925)

± In 1889, began his classic work on sympathetictransmission in autonomic ganglia.

± He blocked synaptic transmission in the ganglia bypainting them with nicotine and then mapped thedistribution of the presynaptic and postsynapticautonomic nerves

± He observed the similarity between the effects of injection of adrenal glands and stimulation of thesympathetic nerves.



John J. Abel

The active principal of adrenal medullary

extracts was called epinephrine by John J.

Abel (1837-1938) in 1897.

With his discovery of the hormone

epinephrine, he uncovered one of the most

commonly used lifesaving agents in the

anesthesiologists pharmacopoeia.



Hx of Sympathetics

Thomas R. Elliot (1877-1961)

± Postulated that sympatheitc nerve impulses release a substancesimilar to epinephrine and considered the substance to be a chemicalstep in the process of neurotransmission.

George Barger and Henry H. Dale ± Studied the pharmacologic activity of a large series of synthetic

amines related to epinephrine and called these drugssympathomimetic.

Walter B. Cannon and Ulf Svante von Euler

±

Studied the different effects on end organs produced by adrenalextracts and sympathetic stimulation

± They demonstrated that the sympathetic nerves released NE, whereasthe adrenal gland released both Epinephrine and NE.



Hx of Parasympathetics

Walter E. Dixon (1871-1931)

Henry H. Dale

± Investigated the pharmacological properties of

acetycholine and was impressed that its effectsreproduced the same

± Observed that the alkaloid muscarine had the same effect

as stimulation of the vagus nerves on various end organs.

± He proposed that the nerve liberated a muscarine-likechemical that acted as a chemical mediator.

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