Evolution of Monitoring in Anesthesia and Critical Care

Rashid M Khan; Maher  Al-Bahrani

SECTION 1

1INTRODUCTION

Evolution of Monitoring in Anesthesia and Critical CareCHAPTER 1

Rashid M Khan

Maher Al-Bahrani

INTRODUCTION

Surgery is as old as humanity. Ancient surgery was an art that thrived in India, China, Egypt, and Greece. In those days emphasis was on surgeon's speed and patient's tolerance. Surgery was at times ruthless and chilling and anesthesia nonexistent. In most cases, surgery was not performed by persons with medical background but by ignorant barbers who wielded the knife. Contemporary surgical advancements have been made possible by the evolution of anesthesia and monitoring devices that are being increasingly used during the perioperative period. Evolution of each monitoring technique and device over the centuries has been like baby steps with plenty of slips and tumbles. Gradual experience with successful intraoperative monitoring led to the emergence of critical care units (CCUs). Today, the two are at par in terms of advanced monitoring aids and they complement each other well.

It is now well established that close monitoring in operation theatre (OT) and CCU has been largely responsible for improvement in patient's outcome. Recognition of the importance of close monitoring evolved with the realization that unexpected mortality and morbidity in the OTs and CCUs may be prevented by early recognition of deterioration and prompt resuscitation of sick patients.^1,2 Likewise, improved monitoring has been cited as one of the most important reasons for a reduction in anaesthesia related mortality over the years and advancements made in surgery.³

This chapter shall take its readers down the memory lane of evolution of monitoring dating back several centuries. Aim has been to arrange them in chronological order.

Early Advocacy of Monitoring Respiration, Heart Sounds, Pulse, and Skin Color

Evolution of patient monitoring started long before the introduction of clinical anesthesia in 1846. In the prehistory period where attempts were made to produce a state resembling anesthesia, using alcohol (Powell 1996) and opium poppy as early as 3400 BC,^4–6 surgeon's speed was of paramount importance rather than patient monitoring. Though William Harvey and Motu Cordis demonstrated arterial and venous blood flow in 1628 and Stephen Hales measured arterial blood pressure in a horse a century later, no formal attempt was made to monitor patients during hypnosis and sedation for surgery till after the demonstration of general anesthesia by William TG Morton in 1846 and John Snow in 1847. In fact, it was the death of a 15-year-old Hannah Greener in 1848 that stimulated the anesthetic fraternity to initiate monitoring of pulse, respiration, and color of patient's skin during surgery. Two years later, Florence Nightingale also emphasized the importance of close patient monitoring. She made a revolutionary step towards modern critical care during the Crimean War in the 1850s. A key component of her intensive care supervision of patients with severe trauma was the frequency and intensity of monitoring by a designated nurse besides scrupulous wound hygiene.⁷

A few years later, in 1855, James Symes gave a lecture on the superiority of chloroform over ether, provided patient's respiration that was closely monitored.⁸ Joseph Lister, a prominent surgeon of Scotland and United Kingdom was so against monitoring pulse during anesthesia that he wrote “palpating the pulse was a most serious mistake. As a general rule, the safety of the patient will be most promoted by disregarding it altogether, so that the attention may be devoted exclusively to the breathing”. He further instructed his students who performed the task of anesthesiologists that “they strictly carry out simple instructions, among which is that of never touching the pulse, in order that their attention may not be distracted from the respiration”.⁹ In addition, he advocated that there was no need to have special anesthetists during surgery provided surgeon's assistants followed simple routines while chloroform anesthesia was being administered.

In contrast to Joseph Lister, Joseph Thomas Clover, who worked as a leading anesthetist between 1846 and 1882, advocated that patient's pulse be closely observed during anesthesia and any irregularities should be immediately dealt by discontinuing anesthetic. James Young Simpson also echoed on similar lines during administration of chloroform anesthesia. He advocated extreme caution when patient started snoring and the pulse became “languid”.¹⁰

In subsequent years, several deaths occurred during chloroform anesthesia and a commission was set up to investigate the cause of deaths. In 1889, the second Hyderabad Commission concluded that the cause of deaths were respiratory depression and not adverse cardiac events. The commission recommended that during chloroform anesthesia only respiration should be monitored. They asserted that monitoring the size of pupil and pulses were not essential.¹¹

The earliest reference to the auscultation of heart sound in OTs was 50 years after the demonstration of ether anesthesia. The credit goes to Robert Kirk of Glasgow Western Infirmary who gave a succinct account of heart sound auscultation in OTs in 1896.¹² He initially used a binaural stethoscope with extended Indian rubber tubing but later on auscultated the heart sound using a phonendoscope. In early 1909, Charles K Teter advocated using the stethoscope intraoperatively in poor risk patients. He wrote that stethoscope provided uninterrupted information of any changes in heartbeat and respiration and averted serious complications.¹³ Surprisingly, esophageal stethoscope was described in 1893 but was not accepted as a routine monitoring aid until 75-years later.

With intraoperative monitoring firmly entrenched in anesthetic practice, it was realized that a record should be kept. Raymond Fink and AE Codman who worked at the Massachusetts General Hospital get the credit for the first anesthetic record in 1894.¹¹

Evolution of Noninvasive Blood Pressure and Eye Signs as Monitoring Aids

Harvey Cushing has been credited for introducing monitoring of intraoperative blood pressure. He got this idea after meeting Scipione Riva-Rocci in 1901, who had developed a sphygmomanometer for indirect measurement of blood pressure.¹⁴ Unfortunately, at that time there were no known normal values for systolic blood pressure. This necessitated that only trends of systolic blood pressure changes were noted during surgery. Four years later, Korotkoff described sounds heard distal to the occlusion as the flow was allowed to resume.¹⁵ At that time, bicycle tubes were used as the blood pressure cuff. Being narrow, it gave excessively high blood pressure readings. This limitation was overcome by von Recklinghausen who introduced a wider cuff for a more accurate blood pressure reading.¹⁶ He went on to develop a semiautomated blood pressure measuring device in 1931 known as oscillotonometer. It was not until 50 years later that fully automated Dinamap was introduced into clinical practice for recording noninvasive blood pressure.¹⁷

Stalwarts of modern anesthesia like John Snow acknowledged the importance of monitoring the depth of anesthesia. However, the ultimate credit for a comprehensive staging of anesthesia depth goes to Arthur Guedel who gave a detailed description of eye signs during ether anesthesia.¹⁸ Arthur Guedel was instrumental in developing a chart of the signs of different stages of ether anesthesia in the 1920s. He would make a weekly round of hospitals 3to check whether trainee anesthetists at six hospitals under his supervision were complying with proper documentation or not. It is to be remembered that the corneal and eyelash reflexes as known today were not mentioned in the early years.

Evolution of Direct Measurement of Arterial Blood Pressure, Electro-cardiography, Pulmonary Artery Catheterization, and Ventilators

Direct measurement of arterial blood pressure was delayed due to the problems of vascular access, sepsis, and nonavailability of material to be used for gaining vascular access. Continuous recording of arterial blood pressure during anesthesia and surgery began with the advent of nonthrombogenic plastic material in 1945–46 for cannulation of the artery.¹⁹ Though the value of direct arterial pressure measurement by performing cut-down was recognized at that time yet the technique remained unpopular as it was considered too expensive. The 1960s saw the emergence of catheter-over-needle technique for gaining a smoother percutaneous placement of cannulae by anesthesiologists and intensive care specialists. With explosion of technology in pressure transducers and continuous flush systems, transistor based display units emerged. Invasive arterial pressure monitoring soon became a common sight in ICUs and OTs.

Heard and Strauss were the first to report the use of electrocardiography (ECG) during anesthesia in 1918.²⁰ It was 4 years later that the first prospective study of electrocardiographic changes during anesthesia was published by Lennox et al.²¹ At that time electrocardiographic tracings were obtained from a string galvanometer. If a permanent record was required, the tracing paper had to be exposed to light. Although conduction abnormalities and premature beats were present in 30% and 22% of Lennox et al.'s patients, respectively, the anesthetist noted none. The value of ECG during anesthesia and surgery was realized at that time but its intermittent recording and delay in developing the tracings hampered its routine use.

Himmelstein and Scheiner described the first prototype of modern day cardioscope in 1952. This was called cardiotachoscope that displayed ECG on a cathode ray screen.²² As continuous monitoring of ECG became common, lead II was routinely selected as the axis paralleled the P-wave vector. A few years later, Kaplan suggested that a modified V5 of a 12-lead electrocardiogram would be more suited to detect myocardial ischemia during anesthesia. Monitoring modified V5 still has a prominent place during the perianesthetic period.

As more and more high risk patients were being taken for operative procedures and management in CCUs, it was realized that an important aspect of patient management was paying close attention to hemodynamic variables. The monitoring device that received considerable attention in this regard was the pulmonary artery (or Swan-Ganz) catheter. It was in 1929 that Warner Forssmann introduced a catheter into his own heart and demonstrated that catheterization of the right heart is possible in humans. But it was only in 1970 that the first balloon flotation flow-directed catheters were introduced in clinical practice by Swan and Ganz.²³ Use of Swan-Ganz catheterization soon became accepted as the gold standard to assess cardiac output and other hemodynamic variables. Though pulmonary artery catheterization became a standard of care and several papers appeared in its support but very little thought was given to critically evaluate its usefulness in clinical practice till 1995. A study by Gattinoni et al. in 1995 clearly showed no benefit for treatment aimed at achieving target values for hemodynamic variables in critical care patients using pulmonary artery catheters.²⁴ In later years, others also questioned the usefulness of hemodynamic monitoring using pulmonary artery.^25–27 Today, this monitoring is on the decline both in the CCUs and the OTs except in patients who are very sick and have advanced cardiac comorbidities.

Around that time, a landmark event in critical care management took place in 1952 in Copenhagen where the dreaded polio epidemic struck the city's population. Bjorn Ibsen, a Danish anesthetist, demonstrated that these patients could be cared through their illness by ventilating them with a mixture of oxygen and nitrogen via a tracheostomy, and by manually clearing their secretions. This resulted in drastic reduction in polio mortality from 80% to 425%. This epidemic drove the development of artificial ventilation and breeds of ventilators. With the advent of ventilators in the CCUs, patient safety concerns took a front seat and propelled transition of monitoring techniques from the operating room to early intensive care units (ICUs) as necessitated by these catastrophic epidemics of the 1950s.

Bjorn Ibsen went on to create the world's first ICU in 1953. This was soon emulated in most parts of the world.²⁸ Since then ICUs have grown into a separate specialty across the world with major advances taking place in developing sophisticated ventilators, renal replacement therapy, and above all modern monitoring systems. Bedside physiologic monitoring displays were introduced into the CCU in the 1970s. Today we have progressed to a stage where we have monitored and supervised ICUs via tele or remote CCU systems.²⁹

Even in early days of CCU evolution, it was realized that physiological parameters such as respiratory rate, heart rate, blood pressure, and level of consciousness deteriorated earlier to any serious adverse event.³⁰

Emergence of Neuromuscular Monitoring

Griffith and Johnson introduced d-tubocurarine into anesthetic clinical practice in 1942.³¹ Though considered to be a safe muscle relaxant by these pioneers, a sixfold mortality was noted in patients receiving d-tubocurarine by Beecher and Todd.³² This was attributed to a lack of guidelines for monitoring muscle strength during the administration of neuromuscular blocker and at the time of conclusion of surgery. This led to the development of peripheral neuromuscular monitors to assess depth of block and recovery from residual neuromuscular paralysis after antagonizing the block. Early reports indicated their usefulness and efficacy.^33,34 However, it was over a decade later that Ali et al. reported the usefulness of monitoring neuromuscular block using train-of-four (TOF) ratio in early 1970s.^35,36 They advised that a TOF ratio of 0.6 is an adequate sign of recovery from neuromuscular blockade. Gradually, reports started appearing that at TOF ratio of 0.6, there is a decreased upper esophageal tone resulting in poor coordination of the esophageal muscles.^37,38 This could result in poor swallowing with resultant risk of aspiration. It was soon emphasized that recovery of TOF ratio to 0.9 and above is essential for restoring esophageal tone and pharyngeal coordination. Subsequently, other modes of neuromuscular monitoring appeared that included twitch-tetanus-twitch, double burst, and post-tetanic count for assessing deeper level of neuromuscular paralysis.

Evolution of Modern Concept of Noninvasive Patient Monitoring in Critical Care Units and Operation Theatres

Tracing the history of the evolution of modern monitoring in CCU and anesthetic practice in the 20^th century shows a biphasic trend. Concept of monitoring had been slow to evolve till 1980s. Thereafter, patient monitoring technology gained momentum with greater emphasis on precision and noninvasive nature of monitors. Electronic monitoring of inspired oxygen measurement, pulse oximetry, and capnography with their audible physiologic alarms replaced human senses in subsequent years.

The first giant steps in the evolution of noninvasive patient monitoring prior to 1980s began with pulse oximetry. The concept of pulse oximetry dated back to 1935 when Carl Mathes built the first prototype device to continuously measure oxygen saturation in blood. It had serious limitations in terms of difficult calibration and nonavailability of absolute values. The concept was not lost and in 1964, Robert Shaw built a self-calibrating ear oximeter. Hewlett Packard in 1970 marketed this for clinical use. But the evolution of today's pulse oximeter was realized with the understanding that only the pulsatile component would give the true oxygen in arterial blood.³⁹

In the 1980s, evidence quickly mounted that the pulse oximeter was far better than the anesthesiologist or intensivists in recognizing arterial hypoxemia. This was evident from observations that the attending anesthesiologist missed out nearly two-thirds of desaturation episodes in children and adults when they were not aided by the pulse oximeter.^40–42

However, questions were soon raised whether detection of hypoxemia by pulse oximetry allowed any benefit to the patient. 5A Cochrane review of four trials comprising 21,773 patients published in 2003 reported that though pulse oximetry could detect perioperative hypoxemia there was little evidence that it made a change in outcome of anesthesia and perioperative morbidity and mortality.⁴³ A possible explanation for this conclusion could be that though pulse oximetry was certainly beneficial in diagnosing hypoxemia but the number needed to treat to avoid one adverse event was very large and not covered by the sample size of this Cochrane review. Despite all this debate, one cannot deny the usefulness of pulse oximetry in our CCUs and OTs today. In fact, if anesthesiologist or the intensivists were to be asked for only one monitor, most would choose a pulse oximeter. Initially, pulse oximters were stand-alone units, but today they are incorporated as part of a larger multipurpose monitor.

Nearly at the same time, in 1978, capnography was introduced into clinical practice in the United States of America. Like the pulse oximetry, the concept of capnography was born much earlier in early 20^th century when John Scott Haldane (1860–1936) described a carbon dioxide analyzer. It was nearly five decades later that five anesthesiologists attended the launch of clinical capnography in 1978. The occasion was the world congress of intensive care medicine. Two of the five anesthesiologists present concluded that it had “little value”. The idea was never lost and soon malpractice insurers started offering massive discounts for anesthesiologists who utilized capnography to distinguish tracheal intubation from esophageal placement of tracheal tube. Importance of capnography was given an additional thrust by the report of the American Society of Anesthesiologists that presence of breath sound on chest auscultation was recorded in 18 out of 29 patients with unrecognized esophageal intubation. The usefulness of capnography was not only limited to tracheal intubations but also to identify successful cardiopulmonary resuscitation besides helping in the diagnosis of pulmonary embolism in the OTs and CCUs. Today, we not only have the formal capnography monitors in all our anesthesia machines and CCUs but also have developed portable miniaturized electronic or semiquantitative colorimetric devices based on litmus paper technology to assist in care of patients in the prehospital setting.⁴⁴

As early as 1870s, physiologists were aware of electrical impulse formation in the brain. An evolutionary step in monitoring took place with the introduction of monitors for measuring the depth of anesthesia using electroencephalographic signal after appropriate processing in 1990s. This came to be known as bispectral index (BIS) monitor. Bispectral index was heralded to be our answer in preventing intraoperative awareness, anesthetic agent cost-cutting, and quicker discharge from postanesthetic recovery room. Though it was sufficiently simple to be used as a routine monitoring aid particularly in OTs, it was found to make only a modest impact on the reduction of hypnotic and sedatives used during anesthesia.^45–48 It was also observed that it did not help in cost-cutting significantly as the cost of consumables required nullified any such advantage.⁴⁹ In addition, it was also demonstrated that the discharge time from the postanesthetic recovery room was not shortened by the intraoperative use of BIS.^45–48 Above all, a large Australian study published in 2006 clearly demonstrated that BIS monitoring reduced but did not prevent intraoperative awareness with any surety.⁵⁰

A yet another milestone in the evolution of monitoring after 1980s had been the introduction of a simple yet fairly reliable noninvasive device to measure stroke volume and cardiac output in anesthetized patients. This device came to be known as esophageal Doppler cardiac output monitor. It is being successfully used to monitor fluid status and helps in replacing circulating volume to a target stroke volume and cardiac output.⁵¹

The “digital revolution” of the 21^st century has heralded greater emphasis to refine noninvasive hemodynamic monitoring. Today, invasive arterial, central venous, and pulmonary wedge pressure monitoring is being reserved for seriously ill patients and those undergoing complex cardiac surgery. Due to advancement and refinement of technology, the noninvasive monitoring is able to match the gold standard set by invasive monitors. The technology is based on photoplethysmography, arterial tonometry, and pulse transit time analysis. The first technology has been well studied and validated, the other two are still in the process of refinement.⁵²6

As we stand today, most of the modern CCUs of recent times have a centralized patient monitoring system. They provide the networking of several bedside patient monitors with a central monitoring station. The monitoring systems have advanced to a level that they track the physiological parameters of patients and alert staff to abnormalities with speed and accuracy using data fusion process. It is not uncommon to have critical care patients remotely monitored. The main aim behind this technology is to extend critical care monitoring facilities using wireless Personal Digital Assistant (PDA) device. With the PDA, the medical staff can gain access to all patient information in real time generated by the bedside monitors on secure wireless communication channels. This remote patient monitoring can be done both from inside and outside the hospital site.

The question remains: Have we reached the pinnacle of monitoring? The answer is a definite “no”. We have miles to go before we can slow down in our search for the ultimate patient monitoring system.

CONCLUSION

The history of the evolution of monitoring in anesthesia and CCU is fascinating. A remarkable group of dedicated physicians gave their today for the better future of our patients in OTs and CCUs. They persevered to advance perioperative and intensive cares by close monitoring of patients despite resistance from peers who did not agree with their vision. The evolution of monitoring in anesthesia and CCUs shows with great clarity the impact that it had on patient care and emergence of sophisticated surgical procedures. However, with advances in monitoring techniques and devices, it is not uncommon to note regression of clinician observation of physical signs in OTs and CCUs, a sad reminder of the misuse of technology. The lessons to be taken from this chapter is that there is scope for further development and refinement in our monitoring equipments and techniques, and that our future generation of care providers will certainly remember those perioperative anesthetists and intensivists who help to advance the science of future monitoring to perfection.

REFERENCES

Hillman KM, Bristow PJ, Chey T, Daffurn K, Jacques T, Norman SL, et al. Antecedents to hospital deaths. Intern Med J. 2001;31(6):343–8.

Kause J, Smith G, Prytherch D, Parr M, Flabouris A, Hillman K, et al. A comparison of antecedents to cardiac arrests, deaths and emergency intensive care admissions in 21 Australia and New Zealand, and the United Kingdom—the ACADEMIA study. Resuscitation. 2004;62(3):275–82.

Tinker JH, Dull DL, Caplan RA, Ward RJ, Cheney FW. Role of monitoring devices in prevention of anesthetic mishaps: a closed claims analysis. Anesthesiology. 1989;71(4):541–6.

The origins and ancient history of wine. In: McGovern PE, Fleming SJ, Katz SH, editor. Food and Nutrition in History and Anthropology, 1st ed. Amsterdam: Gordon and Breach Publishers; 1996.

Evans TC. The opium question, with special reference to Persia (book review). Transactions of the Royal Society of Tropical Medicine and Hygiene. 1928;21:339–40.

The discovery of dreams. In: Booth M, editor. Opium: A History. London: Simon & Schuster; 1996.

Marsh S. The evolution of critical care outreach. Am J Crit Care. 2010;19:315–7.

Ellis RH, Sykes WS, editors. Essays on the First Hundred Years of Anesthesia. Edinburg: E & S Livingstone Ltd.; 1960.

Cumberlege G, editor. The Jubilee of Anaesthesia. London: Oxford University Press; 1947.

Simpson WG, editor. Works of Sir J. J. Simpson. New York: Appleton & Co.; 1872.

Onishchuk, JL. In: Fink BR, Morris LE, Stephen CR, editors. The history of anesthesia. Third International Symposium Proceedings. Illinois: Wood Library Museum of Anaesthesiology; 1992.

Kirk R. On auscultation of the heart during chloroform narcosis. Br Med J. 1896;2(1876):1704–6.

Teter CK. Thirteen thousand administrations of nitrous oxide with oxygen as an anesthetic. JAMA. 1909;53:448–54.

Bier A. In: Faulconer A, Keyes TE, editors. Foundations of Anesthesiology. Illinois, Springfield: Charles C Thomas; 1965.

Korotkoff NS. On the subject of methods of determining blood pressure. Bull Imp Mel Med Acad. 1905;11:365.

von Recklinghausen H. Ueber Blutdruckmessung bein menschen. Arch F Exp Path U Pharmakol. 1901;46:78.

Silas JH, Barker AT, Ramsey LE. Clinical evaluation of Dinamap 845 automated blood pressure recorder. Br Heart J. 1980;43(2):202–5.

Gillespie NA. The signs of anesthesia. Anesth Analg. 1943;22:275–82.

Peterson LH, Dripps RD, Risman GC. A method for recording the arterial pressure pulse and blood pressure in man. Am Heart J. 1949;37(5):771–82.

Heard JD, Strauss AE. A report on the electrocardiographic study of two cases of nodal rhythm exhibiting R-P intervals. Am J Med Soc. 1918;75:238–51.

Lennox WG, Graves RC, Levine SA. An electrocardiographic study of fifty patients during operation. Arch Int Med. 1922;30:57–72.

Himmelstein A, Scheiner M. The cardiotachoscope. Anesthesiology. 1952;13(1):62–4.

7 Swan HJ, Ganz W, Forrester J, Marcus H, Diamond G, Chonette D. Catheterization of the heart in man with the use of a flow-directed balloon-tipped catheter. N Engl J Med. 1970;283(9):447–51.

Gattinoni L, Brazzi L, Pelosi P, Latini R, Tognoni G, Pesenti A, et al. A trial of goal-oriented hemodynamic therapy in critically ill patients. SvO2 Collaborative Group. N Engl J Med. 1995;333(16):1025–32.

Connors AF Jr, Speroff T, Dawson NV, Thomas C, Harrel FE Jr, Wagner D, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients SUPPORT Investigators. JAMA. 1996;276(11):889–97.

Harvey S, Harrison DA, Singer M, Ashcroft J, Jones CM, Elbourne D, et al. Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial. Lancet. 2005;366(9484):472–7.

Chatterjee K. The Swan-Ganz catheters: past, present, and future. Circulation. 2009;119(1):147–52.

Richmond C. Bjørn Ibsen. BMJ. 2007;335(7621):674.

Goran SF. A second set of eyes: An introduction to Tele-ICU. Crit Care Nurse. 2010;30(4):46–55.

Hillman KM, Bristow PJ, Chey T, Daffurn K, Jacques T, Norman SL, et al. Duration of life-threatening antecedents prior to intensive care admission. Intensive Care Med. 2002;28(11):1629–34.

Griffith H, Johnson GE. The use of curare in general anesthesia. Anesthesiology. 1942;3:418–20.

Beecher HK, Todd DP. A study of the deaths associated with anesthesia and surgery: based on a study of 599, 548 anesthesias in ten institutions 1948-1952, inclusive. Ann Surg. 1954;140(1):2–35.

Christie TH, Churchill-Davidson HC. The St. Thomas's Hospital nerve stimulator in diagnosis of prolonged apnoea. Lancet. 1958;1(7024):776.

Churchill-Davidson HC, Christie TH. The diagnosis of neuromuscular block in man. Br J Anaesth. 1959;31:290–301.

Ali HH, Utting JE, Gray TC. Quantitative assessment of residual antidepolarizing block. II. Br J Anaesth. 1971;43(5):478–85.

Ali HH, Kitz RJ. Evaluation of recovery from nondepolarizing neuromuscular block, using a digital neuromuscular transmission analyzer: Preliminary report. Anesth Analg. 1973;52(5):740–5.

Eriksson LI, Sundman E, Olsson R, Nilsson L, Witt H, Ekberg O, et al. Functional assessment of the pharynx at rest and during swallowing in partially paralyzed human: Simultaneous videomanometry and mechanomyography of awake human volunteers. Anesthesiology. 1997;87(5):1035–43.

Sundman E, Witt H, Olsson R, Ekberg O, Kuylenstierna R, Eriksson LI. The incidence and mechanisms of pharyngeal and upper esophageal dysfunction in partially paralyzed humans: pharyngeal videography and simultaneous manometry after atracurium. Anesthesiology. 2000;92(4):977–84.

Kamat V. Pulse oximtery. Ind J Anaesth. 2002;46(4):261–8.

Coté CJ, Goldstein EA, Coté MA, Hoaglin DC, Ryan JF. A single-blind study of pulse oximetry in children. Anesthesiology. 1988;68(2):184–8.

Cote CJ, Rolf N, Liu LM, Goudsouzian NG, Ryan JF, Zaslavsky A, et al. A single-blind study of combined pulse oximetry and capnography in children. Anesthesiology. 1991;74(6):980–7.

Moller JT, Jensen PF, Johannessen NW, Espersen K. Hypoxaemia is reduced by pulse oximetry monitoring in the operating theatre and in the recovery room. Br J Anaesth. 1992;68(2):146–50.

Pedersen T, Dyrlund Pedersen B, Møller AM. Pulse oximetry for perioperative monitoring. Cochrane Database Syst Rev. 2003;(3):CD002013.

Harper CM. Capnography: Clinical aspects. J R Soc Med. 2005;98:184–5.

Başar H, Ozcan S, Buyukkocak U, Akpinar S, Apan A. Effect of bispectral index monitoring on sevoflurane consumption. Eur J Anaesthesiol. 2003;20(5):396–400.

Guignard B, Coste C, Menigaux C, Chauvin M. Reduced isoflurane consumption with bispectral index monitoring. Acta Anaesthesiol Scand. 2001;45(3):308–14.

Pavlin JD, Souter KJ, Hong JY, Freund PR, Bowdle TA, Bower JO. Effects of bispectral index monitoring on recovery from surgical anesthesia in 1,580 inpatients from an academic medical center. Anesthesiology. 2005;102(3):566–73.

Zohar E, Luban I, White PF, Ramati E, Shabat S, Fredman B. Bispectral index monitoring does not improve early recovery of geriatric outpatients undergoing brief surgical procedures. Can J Anaesth. 2006;53(1):20–5.

Yli-Hankala A, Vakkuri A, Annila P, Korttila K. EEG bispectral index monitoring in sevoflurane or propofol anaesthesia: analysis of direct costs and immediate recovery. Acta Anaesthesiol Scand. 1999;43(5):545–9.

Bruhn J, Myles PS, Sneyd R, Struys MM. Depth of anaesthesia monitoring: what's available, what's validated and what's next. Br J Anaesth. 2006;97(1):85–94.

Sinclair S, James S, Singer M. Intraoperative intravascular volume optimisation and length of hospital stay after repair of proximal femoral fracture: randomised controlled trial. BMJ. 1997;315(7113):909–12.

Arora S, Singh PM, Goudra BG, Sinha AC. Changing trends of hemodynamic monitoring in ICU-from invasive to non-invasive methods: Are we there yet? Int J Crit Illn Inj Sci. 2014;4(2):168–77.

Chapter Notes

Evolution of Monitoring in Anesthesia and Critical CareCHAPTER 1