Anesthesia and analgesia
-
Anesthesia and analgesia · Feb 2011
Case ReportsThe possible influence of pulmonary arterio-venous shunt and hypoxic pulmonary vasoconstriction on arterial sevoflurane concentration during one-lung ventilation.
Sevoflurane is widely used for its rapid onset and offset due to a lower blood/gas coefficient. However, involuntary movements, tachycardia, and hypertension have been observed in some patients despite a continuing constantly delivered concentration of sevoflurane during 1-lung ventilation (OLV), indicating the possibility of insufficient depth of anesthesia. We observed a temporary but obvious decrease in arterial sevoflurane concentration and pulse oximeter readings in a patient during OLV. This may have resulted in the depth of inhaled anesthesia being insufficient during OLV because the arterial sevoflurane concentration was lower than expected in spite of constantly delivered and inspiratory/expiratory sevoflurane concentrations.
-
Perception of turnovers may be influenced less by actual turnover times per se than by a mental model of factors influencing turnover times. ⋯ Managers should not rely on surgeons or anesthesiologists for their expert judgment on turnover times. Managers should also not interpret comments about turnover times as literally referring to the time, but instead as factors perceived as contributing to the time (e.g., attitude about the facility and the activity of its personnel).
-
Anesthesia and analgesia · Feb 2011
Pulse oximeter plethysmographic waveform changes in awake, spontaneously breathing, hypovolemic volunteers.
The primary objective of this study was to determine whether alterations in the pulse oximeter waveform characteristics would track progressive reductions in central blood volume. We also assessed whether changes in the pulse oximeter waveform provide an indication of blood loss in the hemorrhaging patient before changes in standard vital signs. ⋯ These results support the use of pulse oximeter waveform analysis as a potential diagnostic tool to detect clinically significant hypovolemia before the onset of cardiovascular decompensation in spontaneously breathing patients.
-
Anesthesia and analgesia · Feb 2011
Measurement of dead space in subjects under general anesthesia using standard anesthesia equipment.
Pulmonary dead space is the volume of gas that is delivered to the lungs but does not participate in gas exchange. Knowing pulmonary dead space in patients under general anesthesia is clinically useful because it can aid in detecting disease processes such as pulmonary emboli or low cardiac output states. Dead space can be simply calculated by using the Bohr equation; however, it is difficult to measure mixed exhaled carbon dioxide (PECO(2)) with a standard anesthesia machine. Previously, a study at our institution demonstrated the carbon dioxide (CO(2)) concentration in the bellows of a standard anesthesia machine is an accurate approximation of PECO(2). In this study, we used the bellows PECO(2) measurement and arterial CO(2) (PaCO(2)) to calculate pulmonary dead space. We verified the technique by adding known apparatus dead space volumes during anesthesia. ⋯ Our baseline dead space measurements were in the expected range under general anesthesia. When dead space was added, we were able to calculate that an increase in dead space occurred. Our calculation was more accurate after adding a 100-mL volume than after adding 200 mL. We present a simple way to detect trends in dead space in ventilated patients using a Narkomed GS anesthesia machine (Dräger Medical, Lübeck, Germany).
-
Anesthesia and analgesia · Feb 2011
The effects of 6% hydroxyethyl starch-hypertonic saline in resuscitation of dogs with hemorrhagic shock.
Hemodynamic and global oxygen transport variables have failed to reflect splanchnic hypoperfusion, resulting in a failure to recognize inadequately treated hemorrhagic shock. Volemic expansion after fluid resuscitation is essential to improve global and regional oxygen in hemorrhagic shock. We hypothesized that, in contrast to conventional plasma expanders, the smaller volemic expansion from 7.5 NaCl/6% hydroxyethyl starch (HHES) solution administration in hemorrhagic shock may provide lesser systemic oxygen delivery and gastric perfusion. We used hemorrhaged dogs to compare intravascular volume expansion and the early systemic oxygenation and gastric perfusion effects of fixed fluid bolus administration, which are usually used in clinical situations with severe hemorrhage, of HHES, lactated Ringer (LR), and 6% hydroxyethyl starch (HES) solutions. ⋯ In dogs submitted to pressure-guided hemorrhagic shock and fixed-volume resuscitation, the smaller intravascular volume expansion from HHES solutions provides worse recovery of systemic oxygenation and gastric perfusion compared with LR and HES solutions despite its high volume expansion efficiency, which was limited by low infused volume.