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The Incas had no written language and their chroniclers say little about their surgery and nothing about their methods for relieving the pain it caused. It is possible that they did have some form of anesthesia. Available plants that had central effects include maize (which they used in different ways to prepare an alcoholic beverage called chicha), Datura, espingo, tobacco, San Pedro cactus, and coca. The Incas used chicha to induce unconsciousness during minor surgical operations and it was still being used in those regions in the 19th century to perform female circumcision. Datura, espingo, tobacco, and San Pedro cactus can produce a deep trance and, in all probability, anesthesia. There is evidence that they used Datura as a total or partial anesthetic. The Incas chewed coca leaves with lime and swallowed the resulting juice, and this allowed them to work long hours without eating or drinking. Modern-day Peruvian Indians say that coca only numbs the mouth, though it was observed in the 19th century that coca leaves placed in wounds provided pain relief. It is possible that the Incas used chicha - probably in combination with another narcotic - to achieve the total or partial anesthesia needed for their surgery. A decoction of coca leaves may have been used as a topical anesthetic.

Objective. —To identify predictors of postoperative myocardial ischemia in patients scheduled to undergo major noncardiac surgery. Design. —Historical, clinical, laboratory, and physiological data were obtained prospectively before and during surgery to identify potential univariate predictors of postoperative myocardial ischemia, which then were entered into multivariate logistic models. Continuous two-lead electrocardiograms before, during, and after surgery were used to identify episodes of myocardial ischemia. Setting. —Department of Veterans Affairs tertiary care hospital. Patients. —A consecutive sample of 474 men at high risk for or with coronary artery disease who were scheduled to undergo major noncardiac surgery (95% compliance rate). Main Outcome Measure. —Significant variables identified by multivariate logistic models that are associated with postoperative myocardial ischemia. Results. —Five major preoperative predictors of postoperative myocardial ischemia were identified: (1) left ventricular hypertrophy by electrocardiogram; (2) history of hypertension; (3) diabetes mellitus; (4) definite coronary artery disease; and (5) use of digoxin. The risk of postoperative myocardial ischemia increased progressively with the number of predictors present: in 22% of patients with no predictors, in 31% with one predictor, in 46% with two predictors, in 70% with three predictors, and in 77% with four predictors. Conclusion. —Patient subgroups who are at high risk for developing postoperative myocardial ischemia and who might benefit the most from intensive Holter monitoring in the postoperative period now can be identified preoperatively. ( JAMA . 1992;268:205-209)

Objective. —Transesophageal echocardiography (TEE) and 12-lead electrocardiography (ECG) are sophisticated techniques that are increasingly being used to monitor for myocardial ischemia during noncardiac surgery. We examined whether the routine use of these techniques has incremental clinical value in identifying patients at high risk for perioperative ischemic outcomes when compared with preoperative clinical data and intraoperative monitoring using continuous two-lead bipolar ECG. Design. —Cohort study. Setting. —Veterans Affairs medical center. Patients. —A total of 332 men undergoing noncardiac surgery who had or were at high risk for coronary artery disease. Interventions. —TEE, 12-lead ECG, and two-lead ECG were performed continuously during noncardiac surgery (47% vascular, 53% nonvascular). Monitoring results were not available to anesthesiologists or surgeons, and data were blindly analyzed after surgery. Main Outcome Measure. —Perioperative ischemic outcomes (cardiac death, nonfatal myocardial infarction, unstable angina). Results. —In a subset of 285 patients who were adequately studied by all three techniques, 111 patients (39%) were identified as having intraoperative myocardial ischemia (by one or more monitoring techniques). By univariate analysis, intraoperative ischemia was associated with all perioperative cardiac outcomes, including ischemic outcomes, congestive heart failure, and ventricular tachycardia ( P ≤.02 for each of the three monitoring techniques). However, when monitoring results for TEE and 12-lead ECG were added to a multivariate model that included preoperative clinical data and continuous two-lead ECG results, the incremental value of TEE was small (odds ratio, 2.6; 95% confidence interval [Cl], 1.2 to 5.7; P =.02) and that of 12-lead ECG was not significant (odds ratio, 1.5; 95% Cl, 0.6 to 3.8). Furthermore, when the multivariate analysis was repeated with only ischemic outcomes, neither TEE nor 12-lead ECG retained significant associations (odds ratio, 2.2; 95% Cl, 0.5 to 9.4, and odds ratio, 1.1; 95% Cl, 0.2 to 6.1, respectively). Conclusion. —When compared with preoperative clinical data and intraoperative monitoring using two-lead ECG, routine monitoring for myocardial ischemia with TEE or 12-lead ECG during noncardiac surgery has little incremental clinical value in identifying patients at high risk for perioperative ischemic outcomes. ( JAMA . 1992;268:210-216)

Objective. —To determine the long-term (2-year) cardiac prognosis of high-risk patients undergoing noncardiac surgery and to determine the predictors of long-term adverse cardiac outcome. Design. —Prospective cohort study. Historical, clinical, and laboratory data were collected during the in-hospital period, and at 6 months, 1 year, and 2 years following surgery. Data were analyzed using proportional hazards models. Setting. —University-affiliated Veterans Affairs medical center. Population. —A consecutive sample of 444 patients with or at high risk for coronary artery disease who had undergone elective noncardiac surgery and were discharged from the hospital in stable condition. Main Outcome Measures. —Cardiac death, myocardial infarction, unstable angina, progressive angina requiring coronary artery bypass graft surgery or coronary angioplasty, and new unstable angina requiring hospitalization. Results. —Forty-seven patients (11%) had major cardiovascular complications during a 728-day (median) follow-up period: 24 had cardiac death; 11, nonfatal myocardial infarction; six, progressive angina requiring coronary artery bypass graft surgery or coronary angioplasty; and six, new unstable angina requiring hospitalization. Thirty percent of outcomes occurred within 6 months of surgery and 64% within 1 year. Five independent predictors of long-term outcome were identified. Three predictors reflected the preexisting chronic disease state: (1) the presence of known vascular disease (hazard ratio, 6.1; 95% confidence interval [Cl], 2.5 to 15.0; P P P P P P Conclusions. —The incidence of long-term adverse cardiac outcomes following noncardiac surgery is substantial. At increased risk are patients with chronic cardiovascular disease; at highest risk are patients with acute perioperative ischemic events. We conclude that survivors of in-hospital perioperative ischemic events, specifically myocardial infarction, unstable angina, and postoperative ischemia, warrant more aggressive long-term follow-up and treatment than is currently practiced. ( JAMA . 1992;268:233-239)

Objective. —To determine the incidence, clinical predictors and prognostic importance of perioperative ventricular arrhythmias. Design. —Prospective cohort study (Study of Perioperative Ischemia). Setting. —University-affiliated Department of Veterans Affairs Medical Center, San Francisco, Calif. Subjects. —A consecutive sample of 230 male patients, with known coronary artery disease (46%) or at high risk of coronary artery disease (54%), undergoing major noncardiac surgical procedures. Measurements. —We recorded cardiac rhythm throughout the preoperative (mean=21 hours), intraoperative (mean=6 hours), and postoperative (mean=38 hours) periods using continuous ambulatory electrocardiographic monitoring. Adverse cardiac outcomes were noted by physicians blinded to information about arrhythmias. Main Results. —Frequent or major ventricular arrhythmias (>30 ventricular ectopic beats per hour, ventricular tachycardia) occurred in 44% of our patients: 21% preoperatively, 16% intraoperatively, and 36% postoperatively. Compared with the preoperative baseline, the severity of arrhythmia increased in only 2% of patients intraoperatively but in 10% postoperatively. Preoperative ventricular arrhythmias were more common in smokers (odds ratio [OR], 4.1; 95% confidence interval [Cl], 1.2 to 15.0), those with a history of congestive heart failure (OR, 4.1; 95% Cl, 1.9 to 9.0), and those with electrocardiographic evidence of myocardial ischemia (OR, 2.2; 95% Cl, 1.1 to 4.7). Preoperative arrhythmias were associated with the occurrence of intraoperative and postoperative arrhythmias (OR, 7.3; 95% CI, 3.3 to 16.0, and OR, 6.4; 95% Cl, 2.7 to 15.0, respectively). Nonfatal myocardial infarction or cardiac death occurred in nine men; these outcomes were not significantly more frequent in those with prior perioperative arrhythmias, albeit with wide Cls (OR, 1.6; 95% CI, 0.4 to 6.2). Conclusion. —Almost half of all high-risk patients undergoing noncardiac surgery have frequent ventricular ectopic beats or nonsustained ventricular tachycardia. Our results suggest that these arrhythmias, when they occur without other signs or symptoms of myocardial infarction, may not require aggressive monitoring or treatment during the perioperative period. (JAMA. 1992;268:217-221)

In 12 patients requiring therapy with mechanical ventilation for acute respiratory failure, total static compliance (Cst) increased from 29 ± 4 ml/cm H 2 O at a tidal volume (TV) of 5 ml/kg to 42 ± 7 ml/cm H 2 O at a TV of 15 ml/kg. Similarly, Cst increased from 42 ± 7 ml/cm H 2 O to 52 ± 8 ml/cm H 2 O between 0 and 6 cm H 2 O of positive end-expiratory pressure (PEEP). At high levels of pulmonary inflation ( ie, high PEEP and large TV) compliance decreased. The changes of total respiratory compliance with TV were mainly due to changes in pulmonary compliance. With PEEP, the functional residual capacity increased, and specific compliance did not change. Two mechanisms may be responsible for the changes in compliance. First, varying TV or PEEP will alter the position of tidal ventilation on the pressure-volume curve, resulting in an increase in compliance with increasing TV and PEEP up to a point, where overdistention occurs and compliance decreases. Secondly, the function of the surface-lowering substance may be altered in acute pulmonary parenchymal disease, thus disturbing the regulation of surface tension over the range of pulmonary Inflation studied.

The role of the anesthesiologist in the management of patients with major trauma is emphasized, with a concentration on those features that relate to airway management and fluid resuscitation. Problems peculiar to thoracic, spinal, and head injuries and trauma to the globe of the eye are outlined.

A precise method for rapid measurement of functional residual capacity (FRC) during mechanical ventilation that uses the simultaneous exchange of argon and nitrogen is described. Circuit leaks were immediately recognizable upon completion of a run, and pneumotachygraphic inaccuracies due to turbulent flows, changes in viscosity, and time delays between pneumotachygraph and mass spectrometer signals were avoided. For 166 duplicate determinations, the first measurement of FRC differed from the second by 0.5 +/- 0.5 per cent (mean +/- SE). The technique does not affect pulmonary gas exchange. During 35 consecutive determinations of FRC (with an inspired oxygen of 50 per cent), mixed expired oxygen and carbon dioxide tensions varied less than 7 and 1.5 torr, respectively.

The management of patients with respiratory insufficiency, using intermittent positive pressure, has been discussed in detail Emphasis has been laid on the underlying physiological problems and on the need for detailed specialized knowledge. The available equipment and methods of use are discussed, together with methods of monitoring assisted respiration. Problems of diagnosis of underventilation, general principles of management and the problems associated with the more common causes of respiratory insufficiency are discussed.

Nous avons fait ľessai, au laboratoire et dans le salle ďoperation, de deux nouveaux ventilateurs a volume constant, debit variable. Ils sont construits pour etre utilises au cours de la chirurgie et nous les avons compares avec ľassociation des Bird Mark IV et Mark VIII. Nous avons fait des comparaisons entre les courbes de pression, de debit et de volume des trois machines. Nous avons porte attention a ľeffet, sur ľair courant, de ľaugmentation du debit et de la resistance elastique; nous avons egalement etudie la vitesse de circulation de ľair et le rapport entre la duree de ľinspiration et celle de ľexpiration. Les deux appareils peuvent donner une bonne constance de volume en depit de ľaugmentation des resistances; il s’agit du ventilateur “Air-Shields Ventimeter” et du ventilateur “Ohio prototype Anesthesia.”

Functional residual capacity (FRC) and alveolarto-arterial oxygen tension difference (A-aDo2) were measured and compared in 16 patients prior to and during halothane: oxygen anesthesia with spontaneous respiration. After an hour of anesthesia (end-tidal halothane 1.0 per cent), FRC had decreased to 81 per cent of awake control values (range 50-104 per cent) and A-aDo2 had increased from a preoperative value of 145 to 232 torr. The decrease in FRC correlated inversely with the changes in A-aDo2 (r = 0.63, P

A report has been made of a series of cases in which severe metabolic acidosis arose, during the rewarming period following hypothermia for cardiac surgery. A further series is reported, showing that this syndrome is not encountered when care is taken to avoid (a) shivering, (b) peripheral vasoconstriction, (c) respiratory alkalosis during cooling and operation, and (d) when spontaneous respiration is established at the earliest opportunity, postoperatively. The differential diagnosis of the causes of severe acidosis in the rewarming period and the treatment of the acute acidotic syndrome are discussed.

Twenty patients requiring ventilation for acute respiratory failure were studied to determine whether intrapulmonary shunt fraction (Qs/Qt) measured at an inspired oxygen concentration (FIO2) of 1.0 differs from Qs/Qt measured at the clinically indicated FIO2 and, if so, the mechanism by which this occurs. Qs/Qt increased from 15.5 +/- 1.8 per cent (mean +/- SE) at the clinically indicated inspired oxygen fraction (FIO2 0.3-0.6) to 21.7 +/- 2.1 per cent after 20 minutes at FIO2 1.0. Functional residual capacity (FRC) decreased by 6 +/- 6 per cent and total compliance (CT) by 10 +/- 6 per cent. Mean pulmonary arterial pressure fell from 21 +/- 2 to 17 +/- 2 mm Hg, whereas pulmonary capillary wedge pressure (PCWP) and cardiac output remained unchanged. Mixed venous oxygen tension increased from 37 +/- 1 to 45 +/- 2 mm Hg with 100 per cent oxygen. At 90 per cent oxygen, Qs/Qt increased from the value at low FIO2, but FRC and CT did not change. Simultaneous application of 100 per cent oxygen and a positive end-expiratory pressure (6 cm H2O) increased FRC, CT and Qs/Qt. Patients with increased PCWP showed smaller increases in Qs/Qt with 100 per cent oxygen. These findings suggest two mechanisms responsible for the increase in Qs/Qt: 1) redistribution of blood flow to nonventilated areas, resulting from the vasodilating effect of an increased oxygen tension in the vessels of hypoxic lung segments; 2) resorption atelectasis. Of the total change in Qs/Qt observed during ventilation with oxygen, 63 per cent was calculated to be due to factors other than a decrease in FRC. (Key words: Ventilation, positive end-expiratory pressure; Oxygen, pulmonary shunt and; Lung, compliance; Lung, shunts.)

In order to evaluate the effects of ultrasonic nebulization on airway resistance in respiratory failure, ten patients requiring mechanical ventilation for acute pulmonary failure were each ventilated with two humidification systems, one producing inspired air saturated with water vapour at 35° C, the other nebulizing water droplets ultrasonically. There was no statistically significant difference in pulmonary resistance at inspira tory flow rates of 40, 60, and 80 1/min. A separate comparison between humidifiers in those patients with the highest resistances did not reveal any difference in response to method of humidification. In contrast to studies in other contexts, these data fail to show any significant difference, from the standpoint of effects on resistance, in the use of ultrasonic mist humidification during mechanical ventilation for respiratory failure.

To determine whether in the management of pulmonary failure, the maximum compliance produced by positive end-expiratory pressure coincides with optimum lung function, 15 normovolemic patients requiring mechanical ventilation for acute pulmonary failure were studied. The end-expiratory pressure resulting in maximum oxygen transport (cardiac output times arterial oxygen content) and the lowest dead-space fraction both resulted in the greatest total static compliance. This end-expiratory pressure varied between 0 and 15 cm of water and correlated inversely with functional residual capacity at zero end-expiratory pressure (r equal -0.72, p less than or equal to 0.005). Mixed venous oxygen tension increased between zero end-expiratory pressure and the end-expiratory pressure resulting in maximum oxygen transport, but then decreased at higher end-expiratory pressures. When measurements of cardiac output or of true mixed venous blood are not available, compliance may be used to indicate the end-expiratory pressure likely to result in optimum cardiopulmonary function.

The usefulness of lung-thorax compliance (or elastance) as an index of pulmonary compliance (or elastance) was examined in 15 patients being ventilated for acute respiratory failure. Mean lung-thorax elastance (ELT) was 27.9 +/- 2.6 cm H2O/L, and the chest wall accounted for 34 +/- 2 percent of the mean total value. Changes in ELT caused by increments of positive end-expiratory pressure correlated only with changes in pulmonary elastance (r = 0.96; P less than 0.001) and not with chest wall elastance, although individual patients varied as to the contribution of the chest wall component. Lung-thorax elastance increased in direct proportion (1:1) to increases in pulmonary elastance, whereas the changes in lung-thorax compliance were only half those in pulmonary compliance. We conclude that elastance is a more useful clinical index than compliance.