Continuous transcutaneous oxygen monitoring during an intraoperative cardiac arrest

A transcutaneous oxygen sensor was used continuously during surgical management of a ruptured abdominal aortic aneurysm. Closed chest compression initiated for intraoperative cardiac arrest gave an inadequate cardiac output on the basis of falling PtcO2 despite transmitted femoral pulses and an excellent PaO2. This discordance provided a rationale for open cardiac massage, which increased the cardiac output and tissue perfusion (PtcO2) needed for successful resuscitation. The PtcO2 sensor provides immediate, non-invasive, and continuous information regarding tissue oxygenation. It reflects the PaO2 in hemodynamically stable patients as well as providing a sensitive indicator for inadequate cardiac output during shock. In patients undergoing cardiopulmonary resuscitation, a falling PtcO2 with an acceptable PaO2 indicates poor tissue perfusion and, in select circumstances, may warrant open cardiac massage.     

Stab wound to the chest with acute pericardial tamponade

A 21-year-old male presented to the trauma unit after he was stabbed once with a knife in the left anterior chest. The patient was awake and combative, very intoxicated, with a systolic blood pressure of 90 mmHg by palpation and a heart rate of 110 beats per min. Physical examination revealed distended neck veins, a single 1.5 cm stab wound to the left parasternal area at the third ICS (noted by clip on x-ray, Fig. 1), poorly auscultated heart sounds, and palpable femoral pulses that went away with inspiration. Chest radiograph (Fig. 1) showed a “pear-shaped” cardiac silhouette, though not markedly enlarged, and a significant left hemothorax. A diagnosis of acute pericardial tamponade was made, and the patient was taken immediately to the operating room for thoracotomy and successful repair of a stab wound of the right ventricle.

Figure 2 (courtesy of Richard Wolfe, MD, Massachusetts General Hospital, Boston, MA) presents an example of an echocardiogram depicting a pericardial effusion. Pericardial fluid is imaged as a black (hypoechoic) crescent area separating the apex of the heart from the pericardium, seen as a white ring (arrow) at the inferior aspect of the scan.

Tamponade is defined sonographically as the presence of both pericardial effusion (PE) and diastolic collapse of the right ventricle. Figure 3 (courtesy of Michael H. Picard, MD, of Harvard Medical School, Boston, MA) demonstrates the collapse of the right ventricular outflow track (RVOT) and its position relative to the left ventricle (LV), the left atrium (LA), and the aortic valve (AV).     

Noninvasive arterial hemoglobin oxygen saturation versus transcutaneous oxygen tension monitoring in the preterm infant

We found that results from a transcutaneous arterial hemoglobin oxygen-saturation monitor correlated well with those from a co-oximeter. The monitor was not disturbed by differing hematocrit levels, the presence of fetal hemoglobin, or hypotension. We also found that the results of simultaneous transcutaneous arterial hemoglobin oxygen saturation (StcaO2) and transcutaneous oxygen tension (PtcO2) monitoring were predictably correlated over a wide range of hemoglobin saturations in preterm infants. When StcaO2 was between 80% and 95%, PtcO2 was at a safe level of 40 to 80 torr in 94% of the patients studied. StcaO2 monitoring as an index of arterial oxygenation has several advantages for the preterm infant.     

The perioperative management of pericardial tamponade.

A case report of a patient with acute pericardial tamponade is presented. The etiology, pathophysiology, and management of cardiac tamponade is discussed. Preoperative management includes volume expansion, administration of catecholamines, and pericardiocentesis. Intraoperatively, monitoring should include continuous measurement of arterial and central venous pressures. Ketamine has been found to be very useful in these patients.     

Localized pericardial tamponade: Difficult echocardiographic diagnosis of a rare complication after cardiac surgery

We report 2 cases of localized pericardial tamponade occurring soon after cardiac surgery, in which the diagnosis could not be made with transthoracic echocardiography. Computed tomography and transesophageal echocardiography, respectively, were necessary, and this underlies the importance of alternative imaging modalities when this condition is suspected. A high index of suspicion is crucial for reaching the correct diagnosis.     

Toe temperature versus transcutaneous oxygen tension monitoring during acute circulatory failure

Measurements of toe temperature and transcutaneous PO₂ (P_tcO₂) have been both suggested for non-invasive assessment of peripheral blood flow in acute circulatory failure. The underlying principle of the two methods is that cutaneous vasoconstriction occurs early when tissue perfusion is altered. In 15 patients, we compared the two measurements during cardiogenic shock (27 measurements) or septic shock (29 measurements). Toe-ambiant temperature gradient and P_tcO₂ correlated well together (r=0.66, p(0.001) especially in hyperkinetic septic shock (r=0.79, p(0.001). In cardiogenic shock, toe-ambiant temperature correlated well with cardiac index (r=0.63), stroke index (r=0.64) and oxygen transport (r=0.65), and these correlations were stronger than for P_tcO₂. In septic shock, both techniques were poor indicators of blood flow indexes but P_tcO₂ rather correlated with arterial pressure (r=0.66) and left ventricular work (r=0.66). Trend evaluation of data revealed in cardiogenic shock that the increase in toe temperature usually preceded the increase in P_tcO₂. Since measurement of P_tcO₂ is technically more complicated, correlates less well with standard hemodynamic parameters and later reflects cardiovascular improvement, it has no advantage over measurement of toe temperature in circulatory shock. In cardiogenic shock, measurements of toe temperature can reliably track cardiac output changes. In septic states, however, non-invasive assessment of skin perfusion is of limited interest.     

Continuous conjunctival and transcutaneous oxygen tension monitoring during resuscitation in a patient

Conjunctival (PcjO2) and transcutaneous (PtcO2) oxygen tensions were serially measured in a patient with multiple stab wounds. Even though blood pressure was normal, severe hypovolemia due to hemorrhage was detected in the emergency department by abnormally low PcjO2/PaO2 and PtcO2/PaO2 ratios. The adequacy of resuscitation was established by return of these ratios to normal values. The conjunctival sensor stabilized more rapidly than the transcutaneous sensor and is of greater utility in the emergency setting. It was found that conjunctival and transcutaneous oxygen sensors can play an important role in monitoring clinical state and resuscitation of trauma patients.     

Conjunctival oxygen tension monitoring in experimental septic shock

Continuous non-invasive monitoring of conjunctival oxygen tension (PcjO₂) versus conventional invasive hemodynamic and oxygen transport variables was evaluated in a porcine model of septic shock induced by a continuous i.v. infusion of E.coli endotoxin over 2 hours. Seventeen pigs under ketamine anesthesia and breathing air spontaneously were investigated. PcjO₂, which reflects local oxygen tension at tissue level, correlated significantly at baseline and throughout the septic course with mixed venous oxygen saturation and oxygen utilization coefficient. All these correlations were significant at the 1% level. The corresponding correlations between PcjO₂ and cardiac output were significant at the 5% level. A finding of great importance was that changes in PcjO₂ preceded major changes in the intermittently measured physiological variables such as SvO₂ and cardiac output.We conclude that PcjO₂ monitoring is a valuable non-invasive method and which can provide a continuous assessment of the hemodynamic and oxygenation status in experimental septic shock.     

Halothane interference with transcutaneous oxygen monitoring: in vivo and in vitro

The effect of halothane on electrodes covered with polypropylene and FEP teflon membranes, used for monitoring transcutaneous oxygen tension, was compared in vitro and in patients anesthetized with halothane. In vitro experiments with halothane showed a false increase in PO2 measured by the electrode covered with polypropylene membrane while there was no increase in PO2 values recorded by an electrode covered with teflon membrane. In 15 patients anesthetized with halothane, no interference with transcutaneous oxygen measurement was seen with electrodes covered with either a polypropylene or FEP teflon membrane.     

A successful treatment of cardiac tamponade due to an aortic dissection using open-chest massage

An 81-year-old woman became unconsciousness after complaining of a backache, and then, an ambulance was called. She was suspected to have an aortic dissection by the emergency medical technicians and was transferred to our department. On arrival, she was in shock. Emergency cardiac ultrasound disclosed good wall motion with cardiac tamponade but no complication of aortic regurgitation. Computed tomography of the trunk revealed a type A aortic dissection with cardiac tamponade. During performance of pericardial drainage, she lapsed into cardiopulmonary arrest. Immediately after sterilization of the patient's upper body with compression of the chest wall, we performed a thoracotomy and dissolved the cardiac tamponade by pericardiotomy and obtained her spontaneous circulation. Fortunately, blood discharge was ceased immediately after controlling her blood pressure aggressively. As she complicated pneumonitis, conservative therapy was performed. Her physical condition gradually improved, and she finally could feed herself and communicate. In cases of acute cardiac tamponade, simple pericardiocentesis often is not effective due to the presence of the clot, and a cardiac tamponade by a Stanford type A aortic dissection is highly possible to complicate cardiac arrest, so emergency physicians should be ready to provide immediate open cardiac massage to treat such patients.     

Continuous monitoring of mixed venous oxygen saturation in septic shock

Fiberoptic pulmonary artery catheters provide a practical method for continuously measuring the amount of oxygen in mixed venous blood. To characterize the usefulness of mixed venous oxygen saturation in managing patients with sepsis, we performed serial hemodynamic measurements on 20 patients with documented septic shock. There was a highly significant positive correlation between increases or decreases of 5% or more in mixed venous oxygen saturation and corresponding changes in oxygen delivery (r = 0.95) and oxygen consumption (r = 0.96). Mixed venous oxygen saturation less than 65% was clinically unacceptable in patients with sepsis and was associated with a poor prognosis. In this study, measurement of mixed venous oxygen saturation was a valuable predictor of survival in patients with septic shock and provided a means of continuously monitoring the status of tissue oxygenation.     

Continuous monitoring of tissue oxygen tension during hyperoxia and hypoxia: relation of subcutaneous, transcutaneous, and conjunctival oxygen tension to hemodynamic variables

Subcutaneous, transcutaneous, and conjunctival oxygen tensions (PscO2, PtcO2, and PcjO2, respectively) were measured in anesthetized dogs subjected sequentially to normoxia, hyperoxia, and hypoxia. Intravascular pressure, hemodynamic and oxygen transport variables were measured simultaneously. PtcO2 and PcjO2 closely paralleled PaO2 during normoxia, hyperoxia, and hypoxia over a wide range of arterial oxygen tensions. PtcO2 was reliable over the widest range of PaO2, with a correlation coefficient of .94. The PcjO2/PaO2 index fell at very low PaO2. The PscO2/PaO2 index decreased at both very low and very high PaO2. Only minor changes were found in hemodynamic and oxygen transport variables during hyperoxia. During hypoxia, however, cardiac output and other central hemodynamic measurements increased, while PscO2, PtcO2, and PcjO2 fell. Oxygen delivery and oxygen consumption were maintained or only slightly changed during hypoxia. All three continuous measurements of oxygen tension are reliable indices of PaO2 over a wide range under normovolemic conditions. The instruments for measuring PscO2 and PcjO2 are unheated and therefore may have advantages for human application.