Cardiovascular-pulmonary monitoring in the intensive care unit (Part 1)

The Routine Use of the Pulmonary Artery Catheter Should Be Abandoned

The pulmonary artery catheter (PAC) is the most common method of measuring cardiac output in cardiac surgery. However, its use has always been questioned in terms of survival benefit, specifically with regard to the accuracy of its measurements and its invasive nature, with the potential for serious complications. In this review we aimed to develop a clear understanding of the pitfalls of the use of PAC, and discuss its risks and available alternatives. We conclude that there is no indication for the routine use of PAC such that clinicians should carefully consider the clinical risks and benefits on a patient by patient basis.

Acute Respiratory Failure in Pregnancy

Acute respiratory failure in pregnancy has multiple etiologies, including thromboembolism, amniotic fluid embolism, venous air embolism, aspiration of gastric contents, respiratory infections, asthma, beta-adrenergic tocolytic therapy, and pneumomediastinum and pneu mothorax. Proper management of acute respiratory fail ure in pregnancy requires an understanding of the specific diseases and the normal gestational changes that occur in maternal respiration (decreased functional re sidual capacity, increased minute ventilation, mild respi ratory alkalosis) and hemodynamics (increased cardiac output, increased blood and plasma volume, unchanged central pressures). Knowledge of the determinants of oxygen delivery to fetal tissue (uterine blood flow, pla cental transfer, fetal circulation) and how they are af fected by changes in maternal hemodynamics, position, acid-base status, and medications can help sustain nor mal fetal development, whenever possible, without compromising maternal care. Diagnostic testing such as radiography, hemodynamic monitoring, and fetal moni toring are considered in terms of attendant risk to the mother or the fetus, alterations in normal values related to gestation, and indications for usage. Similarly, the risks and benefits of supportive and specific therapies for the various etiologies of acute respiratory therapy are reviewed.

Misplacement of a pulmonary artery catheter

Placing a flow-directed pulmonary artery catheter (PAC) can be difficult and lead to serious complications. We present the case of an attempted PAC insertion in a patient undergoing implantation of a left ventricular assist device. Although physiologic pressure waveforms were established, plausible measurements of cardiac output and pulmonary capillary wedge pressure were not initially obtainable. Chest radiography showed that the catheter was looped in the pulmonary artery. This malposition could not be visualized intraoperatively by transesophageal echocardiography. The PAC was replaced in the operating room after the left ventricular assist device was implanted.

Pulmonary artery catheters

BACKGROUND

After its introduction in 1970, the use of the pulmonary artery catheter became a central part of the management of critically ill patients in adult and pediatric intensive care units. However, because it was introduced as a class II device, efficacy for its safety and clinical benefit did not exist during the early years of use. This review describes the pulmonary artery catheter and reviews the literature supporting its use.

METHODOLOGY

A search of MEDLINE, PubMed, and the Cochrane Database was made to find literature about pulmonary artery catheter use. Literature for both adult and pediatric patients was reviewed. Guidelines published by the Society for Critical Care Medicine and the American Heart Association were reviewed, including further review of references cited.

RESULTS AND CONCLUSIONS

The evidence supporting the use of the pulmonary artery catheter is mostly limited to level IV (nonrandomized, historical controls, and expert opinion) and level V (case series, uncontrolled studies, and expert opinion). A higher level of evidence supports the use of the pulmonary artery catheter in selected pediatric patients, especially those with pulmonary arterial hypertension and shock refractory to standard fluid resuscitation and vasoactive agents. There are no data to suggest that use of the pulmonary artery catheter increases mortality in children.

Left atrial pressure can be accurately transmitted to the pulmonary artery despite zone 1 conditions

Pulmonary arterial occlusion pressure is not thought to reflect left atrial pressure (Pla) when alveolar pressure (PA) exceeds pulmonary venous pressure because alveolar capillaries collapse and the required continuous fluid column between the pulmonary artery and left atrium is interrupted. However, arterial-to-venous flow can occur when PA exceeds both the pulmonary arterial pressure (Ppa) and pulmonary venous pressure (i.e., in Zone 1 conditions), indicating the existence of a continuous patent vascular channel. Accordingly, Ppa should reflect Pla under these conditions. To investigate this connection cannulas were placed in the pulmonary arteries and left atria of eight excised rabbit lungs. Ppa and Pla were set 5 cm H2O above PA, which ranged from 0 to 25 cm H2O. Pla was then reduced in 2 to 4 cm H2O decrements while recording Ppa when arterial-to-venous flow ceased. At all PAs greater than 0 cm H2O, Pla was accurately reflected by the Ppa when both were exceeded by PA. The greater the PA, the lower the Ppa could track Pla below PA. Pla can be accurately measured by a pulmonary arterial catheter under Zone 1 conditions.

Hemodynamics and positive end-expiratory pressure in critically ill patients

This article examines the factors that affect the transmission of airway pressures to intrathoracic structures. The effects of positive end-expiratory pressure on central venous pressures, cardiac filling pressures, and right and left ventricular function are discussed. Various techniques for estimating intrathoracic pressures and their limitations are reviewed.

Acute dilutional anemia and critical left anterior descending coronary artery stenosis impairs end organ oxygen delivery

OBJECTIVE

Limited cardiac reserve, secondary to coronary disease, may be associated with end organ morbidity. In this study, we investigate the significance of anemia in the pathogenesis of this phenomenon.

DESIGN

Nonrandomized controlled animal trial.

SETTINGS

Animal laboratory in a university hospital.

SUBJECT

Anesthetized dogs. INTERVENTIONS/MEASUREMENTS: Fourteen anesthetized dogs underwent isovolemic hemodilution with 6% hetastarch from a baseline hematocrit of 40 to 20%. Radioactive microspheres were used to evaluate regional blood flow and cardiac index. Systemic oxygen delivery, consumption, serum lactate, and systemic vascular resistance were recorded during each experiment. Arterial venous oxygen difference was determined from arterial and mixed venous blood. Seven dogs had an iatrogenic critical stenosis of their left anterior descending coronary artery (experimental group); seven dogs did not (control).

MAIN RESULTS

Only in the control animals, the cardiac index increased by 35% with hemodilution to 20%. Systemic oxygen delivery decreased in both the control and the experimental animals. Systemic oxygen consumption and lactate levels were unchanged in both groups. In the renal cortex, spleen, distal colon, ileum, gallbladder, and stomach body, regional O2 delivery was significantly decreased with hemodilution to 20% in both groups. This finding was also observed in the left ventricle and cervical spinal cord in the experimental group. In addition, regional O2 delivery was reduced in the spleen, distal colon, and gallbladder with hemodilution to only 30%. Regional blood flow in the stomach body, gallbladder, ileum, renal cortex, and distal colon, in both groups, and the spleen in the control group was unchanged from baseline with hemodilution to 20%. However, regional blood flow under all other circumstances (control or experimental) was significantly increased with hemodilution to 20% with the exception of the spleen, which showed significant regional blood flow decrease in the experimental group only.

CONCLUSIONS

These data suggest that with limited cardiac reserve, anemia may compromise aerobic splanchnic circulation. These observations may further our understanding of the pathogenesis of cholecystitis, gastric stress ulcers, ileal endotoxin translocation, and ischemic colitis in critically ill patients with coronary artery disease.

Diagnosis and therapy of acute respiratory distress syndrome in adults: an international survey

In an attempt to identify the range of opinions influencing the diagnosis and therapy of patients with the adult respiratory distress syndrome (ARDS), a postal survey was mailed to 3,164 physician members of the American Thoracic Society Critical Care Assembly. The questionnaire asked opinions regarding the factors important in the diagnosis of ARDS and its treatment. Thirty-one percent of physicians surveyed responded within 4 weeks, the vast majority of which were board certified or eligible in Internal Medicine, Pulmonary Disease, and/or Critical Care Medicine. A known predisposing cause, measure of oxygenation efficiency, and a chest radiograph depicting pulmonary edema were reported to be the most important criteria for a clinical and research diagnosis of ARDS. Lung compliance and bronchoalveolar lavage neutrophil or protein content were reportedly less important. The initial treatment of patients with ARDS was reported to be most commonly accomplished using volume-cycled ventilation in the assist/control mode. Nearly half the responders reported using lower tidal volumes (5 to 9 mL/kg) than the traditionally recommended 10 to 15 mL/kg. Most respondents indicated they have intentionally allowed CO2 retention. On average, oxygen toxicity was thought to begin at an FIO2 between 0.5 and 0.6. It was reported that modest levels of positive end-expiratory pressure (PEEP) were used in incremental fashion as FiO2 requirements increased. Perceived indications for insertion of pulmonary artery catheters and compensation of the effects of PEEP on the pulmonary artery occlusion pressure varied widely among the responders. We conclude that reported practice patterns regarding the care of ARDS patients vary widely even within a relatively homogenous group of critical care practitioners.

The acute respiratory distress syndrome

ARDS is a complex response of the lung to direct (inhalational) and indirect (hematogenous) insults. It is easy to be pessimistic about the benefit of the approaches we have described, but there is evidence that overall survival has improved in recent years. To maintain this progress, new therapies for ARDS must be rigorously evaluated, and their routine use should be recommended only after careful scrutiny of the evidence. Such a course will eliminate the unnecessary risks and costs often associated with unproved therapies.

Infections in critically ill patients: experience in MICU at a major teaching hospital

During a one-year period 105 patients suffering a total of 134 infectious episodes were studied prospectively in the medical intensive care unit (MICU). These patients included 54 male and 51 female patients, age ranging from 14 to 100 years (median = 54 years). The overall incidence of infection was 46.7%. Infections acquired in medical wards accounted for 47.8% of the total, followed by community-acquired infections in 27.0%, and MICU-acquired infections in 25.2% of the cases. The most frequent infections were pneumonia and septicaemia accounting for 88% of the total, whereas urinary tract (4.4%), gastrointestinal tract (5.0%), skin and wound infections (2.5%) constituted only 11.5%. The pathogens mainly involved were gram-negative rods, Staphylococcus spp. and Streptococcus pneumoniae. However, in community-acquired pneumonia, the major pathogens were gram-negative rods. In addition, Mycobacterium tuberculosis was an important cause of pneumonia in these patients. The majority of patients had a monoinfection; multiple pathogens were isolated in 11.9% of the episodes. The overall mortality was 46.7%. Several factors that influenced the mortality in these patients were analyzed. Early recognition of these factors may reduce morbidity and mortality.

Improved outcome based on fluid management in critically ill patients requiring pulmonary artery catheterization

We performed a randomized, prospective trial to evaluate whether fluid management that emphasized diuresis and fluid restriction in patients with pulmonary edema could affect the development or resolution of extravascular lung water (EVLW), as well as time on mechanical ventilation and time in the intensive care unit (ICU), in critically ill patients requiring pulmonary artery catheterization (PAC). PAC was performed on 101 patients. A total of 52 patients were randomized to an EVLW management group using a protocol based on bedside indicator-dilution measurements of EVLW. The other 49 patients were randomized to a wedge pressure (WP) management group in whom fluid management decisions were guided by WP measurements. A total of 89 patients had pulmonary edema (defined as EVLW greater than 7 ml/kg ideal body weight). Except for a clinically unimportant difference in mean age, the two groups were entirely comparable at baseline. The study groups were managed differently, as evidenced by cumulative input-output of 2,239 +/- 3,695 ml (median = 1,600 ml) in the WP group versus 142 +/- 3,632 ml (median = 754 ml) in the EVLW group (p = 0.001). EVLW decreased significantly, and ventilator-days and ICU days were significantly shorter only in patients from the EVLW group. No clinically significant adverse effect occurred as a result of following the EVLW group algorithm. Thus, a lower positive fluid balance, especially in patients with pulmonary edema regardless of cause, is associated with reduced EVLW, ventilator-days, and ICU days.

Pulmonary "capillary" wedge pressure not the pressure in the pulmonary capillaries

In 1949, Hellems, Haynes, and Dexter proposed that the pressure in a catheter wedged so as to occlude a pulmonary artery was an "estimate" of the pressure in the pulmonary capillaries. Their report led to the designation of this pulmonary artery wedge pressure as the pulmonary "capillary" wedge pressure. In fact, the pulmonary artery wedge pressure is a distorted measure of the pressure in the pulmonary veins. Usually this pressure differs only slightly from the capillary pressure, and the misconception fostered by the inaccurate name is inconsequential; however, sometimes this misconception leads to errors in diagnosis. This report briefly reviews the early history of pulmonary vascular catheterization, offers an explanation of pulmonary artery wedge pressure, and discusses a disease in which pulmonary artery wedge pressure is normal, even though capillary pressure is elevated.

Reversible cardiogenic shock due to chest tube compression of the right ventricle

A 62-year-old woman developed shock immediately after the insertion of a right-sided chest tube. A chest roentgenogram showed the chest tube to be overlying the heart and possibly compressing the right ventricle. An animal model was developed to replicate this clinical situation. Using a domestic goat model pulmonary artery, peripheral arterial catheters were inserted along with a right sided chest tube placed to suction. A second chest tube guided by a flexible fiberoptic bronchoscope placed within its lumen was positioned between the right ventricle and the sternum of the animals. Thirteen paired measurements in three goats (average of 4.3 measurements per animal) of cardiac output, heart rate, and mean arterial blood pressure were made at baseline and after chest tube placement over the right ventricle. The data were analyzed using a paired t test statistic. Compared with baseline measurements, there was a significant decrease in cardiac output (p less than 0.001) and mean arterial pressure (p less than 0.001) as well as an increase in heart rate (p = 0.0056) after placement of the chest tube across the right ventricle. We conclude that a misplaced chest tube compressing the right ventricle can impede cardiac output and lead to a low cardiac output state. Physicians inserting chest tubes in patients should be aware of this potential complication as it is easily treated by withdrawal of the chest tube.

Intact epithelial barrier function is critical for the resolution of alveolar edema in humans

Within 15 min of endotracheal intubation, the resolution of pulmonary edema was studied over the next 12 h in 34 mechanically ventilated patients by (1) serial measurements of the alveolar-arterial oxygen difference, (2) the extent of edema on the initial and follow-up chest radiograph, and (3) by an initial and final measurement of total protein and albumin concentration in sequential samples of pulmonary edema fluid. Based on the oxygenation and chest radiographic data, 24 patients clinically improved and 10 patients did not improve. In the 10 patients who did not clinically improve (3, hydrostatic edema; 7, permeability edema), there was no change in the final edema fluid protein concentration (4.1 +/- 1.1 g/100 ml) compared with the initial edema fluid protein concentration (4.2 +/- 1.0 g/100 ml) (p = ns). However, in the 24 patients who clinically improved (15, hydrostatic edema; 9, permeability edema), there was an increase in every patient's final edema protein concentration (5.6 +/- 2.3 g/100 ml) compared with their initial edema protein concentration (3.8 +/- 1.2 g/100 ml) (p less than 0.01). In 13 of these 24 patients, the final edema fluid concentration (7.3 +/- 1.6 g/100 ml) exceeded the final plasma protein concentration (5.6 +/- 0.8 g/100 ml) by a mean value of 1.7 g/100 ml protein. The data provide the first evidence in humans to support the hypothesis that active ion transport across the alveolar epithelial barrier is the primary mechanism for clearance of edema fluid from the air spaces of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Central venous catheter related sepsis: a clinical review

Central venous catheterization is one of the most common invasive vascular procedures performed in hospitals today. Though catheter related sepsis occurs only in a small percentage of catheterized patients, this complication has a tremendous impact due to the ubiquitous use of central venous catheters and consequent morbidity and even mortality. Recent studies have considerably advanced our knowledge regarding the pathogenesis, diagnosis, and prevention of catheter sepsis. In this paper, current concepts regarding catheter-related sepsis are reviewed, regarding the incidence, pathophysiology, diagnosis, prevention, and therapy of this complication. Particular emphasis is placed upon recent research and clinical advances in this field, which have clarified important question and suggested promising approaches to the prevention and treatment of catheter bacteremia. The excessive morbidity and mortality due to catheter-related sepsis can be markedly decreased, by attention to simple infection control methods, and by future implementation of new experimental techniques.

A microcomputer system for on-line monitoring of pulmonary function during artificial ventilation

Standard monitoring of the artificially ventilated patient in the intensive care unit (ICU) and during anaesthesia includes repeated determinations of arterial blood gases, airway pressure and expired volume. However, there is a need for more extensive monitoring of the critically ill ventilator treated patient, and this is possible by better utilization of modern technology. Information on a variety of variables related to both pulmonary mechanics and gas exchange has long been accessible in the lung-function laboratory. Small, inexpensive microcomputers (PCs), accurate and fast bedside monitors and modern ventilators have also made this information directly available to the ICU staff. This paper describes a microcomputer (PC-XT) system for on-line bedside monitoring of pulmonary function. The microcomputer receives airway pressure, gas-flow and timing signals from the ventilator and signals for carbon dioxide concentration from an infrared analyzer. Data related to pulmonary mechanics and gas exchange are derived and displayed on the computer screen, both numerically and as graphs. In studies of ten artificially ventilated patients the coefficients of variation (CV) were below 10% for directly obtained variables (tidal volume, airway pressure, end-tidal and mixed expired carbon dioxide, carbon dioxide production, airway dead space), whereas the derived variables (compliance, phase III carbon dioxide slope) were associated with greater variability, with CVs ranging from 1.3 to 24% (median 6.25% and 8.65% respectively). The accuracy in estimating dead space variations was checked in two ventilator-treated patients by adding known dead space volumes. Simple regression analysis yielded an r value of 0.98 indicating adequate correctness of measurements and calculations.

The use of crystalloidal and colloidal solutions for volume replacement in hypovolemic shock

A wide variety of colloidal and crystalloidal fluids, as well as blood and blood products, are available to the clinician for treatment of the hypovolemic patient. These fluids vary with respect to the size, shape, and concentrations of electrolytes, colloidal molecules, and/or cellular components, duration of volume-expanding effects, incidence of allergic reactions, and effect on the coagulation system. When these fluids are administered intravenously, their distribution in the vascular, interstitial, and cellular compartments can be predicted from fundamental physiological principles as well as from the results of laboratory and clinical research. It is thus recognized that colloidal fluids and blood provide more rapid expansion of the intravascular space when compared with crystalloidal fluids. Similar volumes of crystalloidal fluids more rapidly expand the interstitial and intracellular spaces. These principles guide therapy in hypovolemic shock. A logical decision regarding intravenous fluid therapy may be based on the nature of the volume deficit (blood, plasma, or selective protein loss, loss of free water and/or electrolytes) and the predicted changes in cellular and extracellular compartments.

Common complications in critically ill patients

Patients in intensive care units (ICUs) are subject to many complications connected with the advanced therapy required for their serious illnesses. Complications of ventilatory support include problems associated with short-term and long-term intubation, barotrauma, gastrointestinal tract bleeding, and weaning errors. Cardiac tachyarrhythmias can arise from a patient's intrinsic cardiac disease, as well as from drug therapy itself. Hemodynamic monitoring is crucial to careful patient management, but it is associated with technical complications during insertion such as pneumothorax, as well as interpretive errors such as those caused by positive end-inspiratory pressure. Acute renal failure can develop as a result both of therapy with drugs such as aminoglycosides and hypotension of many etiologies, as well as the use of contrast media. Nosocomial infection, which is a dreaded complication in ICU patients, usually arises from sources in the urinary tract, bloodstream, or lung. Complications frequently can arise if the interactions of drugs commonly used in the ICU are not recognized. Further, the ICU patient is subject to nutritional complications, acid base problems, and psychological disturbances. This monograph deals with the frequency, etiology, and prevention of these common ICU complications.

Relationships of oxygen uptake and oxygen delivery in respiratory failure not due to the adult respiratory distress syndrome

Previous studies have suggested that oxygen uptake (VO2) may be dependent on oxygen delivery (QO2) at most levels of QO2 in patients with the adult respiratory distress syndrome (ARDS); however, the adequacy of substrate delivery in patients with non-ARDS respiratory failure is unclear. The purpose of the present study was to examine the relationship between VO2 and QO2 in a group of critically ill patients (n = 10) with non-ARDS respiratory failure (ie, cardiac pulmonary edema, chronic obstructive pulmonary disease [COPD], or pneumonia). For comparison, these relationships were also examined in a group of patients (n = 6) with ARDS. The data indicate that VO2 is dependent on QO2 in both patients with ARDS and non-ARDS respiratory failure. In contrast, regional venous oxygen tension differences varied considerably between the two groups of patients, indicating differences in local adaptations to critical reductions in QO2. Finally, over a similar range of QO2, oxygen extraction was greater in patients with ARDS compared to patients with non-ARDS respiratory failure (r = -0.67 and slope = -0.62 vs r = -0.45 and slope = -0.35; p less than 0.05). These data suggest that a linear relationship between VO2 and QO2 is not unique to patients with ARDS and may not predict regional adaptations to critical reductions in substrate availability.

Adult respiratory distress syndrome in pediatric patients. II. Management

Adult respiratory distress syndrome, a clinical syndrome of respiratory failure that follows many kinds of insults, often in patients with no previous pulmonary disease, occurs in pediatric patients. This group of disorders has a typical clinical, pathologic, and pathophysiologic course, the hallmark of which is injury to the alveolar-capillary membrane with increased permeability of the pulmonary vasculature and pulmonary edema. Resolution may occur at any stage, but most patients die and many develop chronic lung disease requiring respiratory support for weeks or months. Multiple organ system failure, secondary infection, and irreversible respiratory dysfunction are responsible for the poor outcome. The underlying mechanisms that relate injury to the development of pulmonary disease are unclear. In some cases there may be direct injury to the lung, but in others, such as septic shock, there are mediators that link the initial insult to the subsequent lung injury. The leukocyte may have a central role in this process, although this is uncertain. Therapeutic measures needed to support the patient, especially increased inspired oxygen, are additional factors in the progression of lung disease. Current therapy, as summarized in Table II, is primarily supportive. Efforts to treat ARDS after it is clinically apparent have been disappointing. The pathogenic mechanisms that lead to ARDS are probably well advanced by the time the syndrome is diagnosed on the basis of the usual clinical signs. Therefore an emphasis on understanding the mechanisms of lung injury so that specific markers can be used to predict which patients will develop ARDS, allowing intervention in the early stages of the process, may prove rewarding.

Peripheral vascular resistance in septic shock: its relation to outcome

To support the concept that patients who die of septic shock have a persistent defect in peripheral vascular tone irrespective of cardiac index (CI), a retrospective study was undertaken of 42 patients with documented septic shock. From the patient records, the single lowest CI (t = 2) measured after initial values (t = 1) with concomitantly obtained haemodynamic and metabolic variables was taken. Group 1 consisted of 21 survivors and group 2 of 21 patients, who had died in shock. Initial haemodynamic and metabolic variables were comparable between the groups, reflecting shock with a hyperdynamic circulation and lactic acidemia. At t = 2, median CI measured 3.21.min-1.m-2 in both groups, but mean arterial pressure (MAP) and systemic vascular resistance index (SVRI) were higher in group 1 than 2 (p less than 0.0005). Changes in arterial blood lactate levels also differed significantly. The rankcorrelation between CI and SVRI at t = 2 was significant in group 1 (rs = -0.69, p less than 0.005) but not in group 2 (rs = -0.34). Our data suggest that when CI decreases in septic shock, patients with a fatal outcome have less capability to augment vascular resistance than survivors. Hence, peripheral vascular failure, even if complicated by inability to maintain an elevated CI, may be a major haemodynamic determinant of mortality in septic shock.

Beyond the wedge: clinical physiology and the Swan-Ganz catheter

The Swan-Ganz catheter was introduced into general clinical medicine in 1970 and quickly gained widespread use in the management of critically ill patients. The device offers highly sophisticated physiologic information; however, in many instances, only the wedge pressure and the cardiac output are utilized when managing acutely ill patients. The purpose of this review is to illustrate and explain the array of physiologic data available from the Swan-Ganz catheter in most circumstances. A basic understanding of the information that can be obtained with the Swan-Ganz catheter is quite useful in the diagnosis and management of a variety of cardiovascular disorders. In addition, the Swan-Ganz catheter can be a helpful tool for teaching cardiovascular pathophysiology.

Air embolism and cardiac arrest in a patient with a pulmonary artery catheter: a possible association

This patient with acute mitral insufficiency suddenly developed hemoptysis and electromechanical dissociation. A post mortem chest X-ray demonstrated a large amount of air in the right ventricular cavity. It is postulated that this air embolism resulted from a catheter-induced rupture of the pulmonary artery.

Swan-Ganz catheter monitoring in neurosurgical patients: theoretical and practical aspects

Theoretical and practical aspects of monitoring cardiac and blood volume status in neurosurgery patients are discussed. Groups of patients unique to neurosurgeons who might benefit from this approach include the following: those with intracranial hypertension; those undergoing blood volume expansion as a treatment for a variety of cerebrovascular disorders; and those with significant cardiovascular-respiratory problems undergoing high-risk or prolonged neurosurgical procedures. In addition, the generation of Starling-type ventrical function curves to be used in fluid management for blood volume expansion in the treatment of neurologic deficits associated with vasospasm is discussed.

Cardiogenic shock

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