Combination of external chest wall oscillation with continuous positive airway pressure.

We studied the effects of continuous positive airway pressure (CPAP) on pulmonary gas exchange during external chest wall oscillation (ECWO), and the relationship with obesity, in nine patients with normal body weight (group 'N') and 10 obese patients (group 'O'). During ECWO with CPAP 5, PaCO2 decreased in group 'O' (6.0 (SD 0.8) to 5.6 (0.5) kPa, P<0.05), whereas it increased in group 'N' at all levels (P<0.01). Arterial PO(2) (P<0.001) was greater and PaCO2 (P<0.01) less in group 'N' during CPPV and ECWO plus CPAP. We also compared the haemodynamic effects of ECWO plus CPAP with those of continuous positive pressure ventilation (CPPV). ECWO plus CPAP and CPPV were applied for 30 min to 6 ASA III patients. Cardiac output (CI 2.7 (0.5) vs 2.1 (0.2) litre x min(-1) x m(-2), P<0.05) and stroke volume (SVI 49 (9) vs 32 (6) ml x m(-2), P<0.05) were greater during ECWO plus CPAP than with CPPV. ECWO is less effective in obese individuals than in those with normal body weight, and the effect of CPAP in overweight individuals is small.

Controlled hypercapnia during one-lung ventilation in patients undergoing pulmonary resection.

BACKGROUND: In a pilot study, the haemodynamic and gas exchange effects of acute hypercapoia during one-lung ventilation in thoracotomy patients were investigated. The effects of normocapnic one-lung ventilation (OLV-N) on haemodynamics and pulmonary gas exchange were compared with those of hypercapnic one-lung ventilation (OLV-H) in 14 patients undergoing pulmonary lobectomy. METHODS: Hypercapnia was induced by decreasing tidal volume until PaCO2 increased to 8-9 kPa. During OLV, minute ventilation was reduced from 8.8+/-1.7 to 4.2+/-0.7 l min(-1). RESULTS: Cardiac index (from 3.3+/-0.6 to 3.9+/-0.6 l min(-1), P<0.01) and pulmonary vascular resistance index (from 245+/-96 to 347+/-125 dyn s cm(-5) m(-2), P<0.05) increased during OLV-H, whereas systemic vascular resistance index decreased from 1952+/-403 to 1636+/-361 dyn s cm(-5) m(-2) (P<0.01). Pulmonary oxygenation remained unchanged. CONCLUSIONS: All patients had an uneventful course during OLV-H. The determinants of pulmonary oxygenation during hypercapnic one-lung ventilation remain to be further elucidated.

Factors determining length of stay of surgical day-case patients.

BACKGROUND AND OBJECTIVE: Factors which lead to prolonged stay in the day-care unit and unplanned admission after day-case surgery are poorly understood. METHODS: Data sets of 3152 day-case patients were collected with a computerized online record keeping system (NarkoData). Predictors of prolonged postoperative stay including unanticipated admission were identified using univariate analysis. Charts of patients, who needed admission, were reviewed. RESULTS: 13.2% of day-case patients had a postoperative stay < or = 3 h, 55.3% 3-6 h and 26.2% > or = 6 h. The rate of unanticipated admission was 5.4%. Intraoperative haemoglobin concentration and blood loss were the best predictors of a prolonged postoperative stay. Other significant predictors were female gender, advanced age, longer duration of surgery, larger volume of infusions, intubation, spinal anaesthesia, intraoperative use of opioids and non-depolarizing muscle relaxants, high pain score, nausea and vomiting and prolonged preoperative waiting time. Chart review of patients admitted to hospital confirmed the validity of the statistically significant predictors. CONCLUSIONS: In day-case surgery, the predictors of prolonged stay in the day-care unit and unplanned Hospital admission are mainly related to the surgical procedure.

[Influences and predictors of unanticipated admission after ambulatory surgery]. / Einflussfaktoren und Prädiktoren für die ungeplante stationäre Aufnahme tageschirurgischer Patienten.

UNLABELLED: In order to plan the daily routine of a surgical day care unit optimally and effectively, it is indispensable to know the causes of unanticipated admission of outpatients. The purpose of this experiment was to evaluate the influences and predictors of unanticipated admission of patients in our day care unit for ambulatory surgery. The data sets of 3152 surgical outpatients were evaluated. The duration of stay had been entered online by computers. METHOD: From January 1997 until June 1999, all clinically relevant parameters from any outpatient were entered into an anesthesia information management system (NarkoData, Imeso GmbH, Hüttenberg-Rechtenbach, Germany). The correlation of potential nominal and ordinal scaled predictors of unanticipated admission was tested using the chi-squared test. Univariate analysis was used in determining predictors for the occurrence of unanticipated admission. Pearson's contingency coefficient (CC) was used as a standard for the correlation rigidity in nominal and ordinal scaled parameters. The correlation standard eta was used for metrical parameters. RESULTS: Unanticipated admission occurred in 169 (5.4%) of the 3152 outpatients. The following parameters significantly influenced unanticipated admission: age, ASA status, diagnosis (ICD-9), time of admission, different anesthesia procedures and anesthetics (opioids and non-depolarizing muscle relaxants), surgical department, type of surgery (ICPM), duration of operation, blood loss, intraoperative hemoglobin values, and the administration of colloid and crystalloid solutions. The parameters blood loss, intraoperative hemoglobin values, and administration of colloid solutions were evaluated as being good predictors. CONCLUSION: The causes of unanticipated admission of patients in our day care unit for ambulatory surgery are manifold. Some relate to the patient, the anesthesia, and the organization of the day care unit, whereas lengthy operative trauma leading to intraoperative blood loss also plays a major role.

Effects of dopexamine and volume loading on hemodynamics and oxygenation parameters in patients undergoing pulmonary resection.

BACKGROUND: Pulmonary resection may result in a reduction in arterial oxygen pressure as well as in cardiac output. Since cardiac index, oxygen delivery, and oxygen consumption are considered as important determinants of patients' outcome, we evaluated the effects of dopexamine and volume loading on cardiopulmonary variables in patients undergoing pulmonary resection. METHODS: Forty adult patients undergoing pulmonary resection for lung or bronchial tumors were included in an open placebo-controlled study. The patients were selected according to a randomized sequence to group A (n=20) or group B (n=20). Dopexamine (2 microg x kg(-1) x min(-1)) was started when steady state conditions were achieved after induction of anesthesia in group A. Saline 0.9% was given as control (group B). Hemodynamic monitoring was performed using a pulmonary artery catheter. RESULTS: Dopexamine increased heart rate, cardiac output and oxygen delivery compared with control without increasing oxygen consumption during anesthesia and surgery. Furthermore, dopexamine was found not to alter the course of PaO2/FiO2 values. CONCLUSION: In patients undergoing pulmonary resection, dopexamine can be used perioperatively to increase cardiac index without decreasing the PaO2/FiO2 ratio.

[Recovery of balanced anesthesia with various inhalation anesthetics in comparison to intravenous anesthetics: a retrospective analysis of 20,060 patients]. / Aufwachverhalten bei balancierten Anästhesien mit unterschiedlichen Inhalationsanästhetika im Vergleich zu intravenösen Anästhesien (IVA): Eine retrospektive Analyse bei 20,060 Patienten.

BACKGROUND: The aim of this investigation was to compare routine balanced anaesthesia with different inhalation agents to intravenous anaesthesia (IVA) using an Anaesthesia-Information-Management-System (AIMS) with regard to time of recovery from anaesthesia, the time of discharge from the postanaesthesia care unit (PACU) and postoperative nausea as well as postoperative therapy with analgesics. METHODS: In 1997 and 1998 all relevant data of each anaesthesia procedure have been recorded using the online documentation Software NarkoData. These data sets have been stored into a relational database during each anaesthesia procedure. For evaluation the information has been exported from the database to a statistics program via 'Structured Query Langvage' (SOL). Balanced anaesthesia has been performed using isoflurane, halothane, and sevoflurane, respectively, supplemented with or without nitrous Oxide (N2O). The intravenous based anaesthesia-groups included propofol-fentanyl or propofol-remifentanil. RESULTS: The fastest recovery was seen in patients of the isoflurane group (11.2 +/- 7.7 minutes), and the longest time for extubation was observed in patients wich halothane anaesthesia (12.8 +/- 9.3 minutes); the overall mean difference was 1.7 minutes. The earliest patient admitted to the PACU had received sevoflurane (7.0 +/- 6.3 minutes) and propofol-remifentanil (7.0 +/- 7.4 minutes) whereas patients of the halothane group (9.5 +/- 7.5 minutes) took more. The shortest stay in PACU was seen in patients of the sevoflurane and isoflurane groups (105.13 +/- 35.7 and 108.4 +/- 60.5 minutes), whereas propofol-remifentanil (126.2 +/- 89.1 minutes) and halothan (120.0 +/- 86.1 minutes) anaesthetised patients had the longest stay in PACU. No difference was noted in the incidence of postoperative nausea and vomiting nor in the amount of postoperatively given analgesics. CONCLUSION: Results achieved in routine correspond only in part to results from studies. In our investigation balanced anaesthesia with isoflurane and sevoflurane correspond with the shortest stay in PACU compared to balanced anaesthesia with halothane and IVAs with propofol-fentanyl or propofol-remifentanil. One reason for this could be the intraoperatively administered opioide piritramide in IVAs. Furthermore we conclude that an AIMS may provide additional information about overall costs-effectiveness. However this information depends largely on local factors, e.g. patient case mix, staffing, policy of discharge from the PACU etc.

Effects of low-dose dopexamine on splanchnic oxygenation during major abdominal surgery.

OBJECTIVE: To study the influence of low-dose dopexamine on splanchnic oxygenation during major abdominal surgery. DESIGN: Prospective, randomized, placebo-controlled study. SETTING: University hospital. PATIENTS: Eighteen adult patients undergoing elective major abdominal surgery. INTERVENTIONS: The patients received either dopexamine at 1 microg/kg/min (group A, n = 9) or 0.90% saline as control (group B, n = 9). MEASUREMENTS AND RESULTS: To assess the splanchnic oxygenation, intestinal tissue PO2 (PtissO2) and gastric intramucosal Pco2 (PmucCO2) were measured, and the PCO2 gap (PmucCO2 - PaCO2) was calculated at baseline (T1) and after an infusion period of 60 mins (T2). There was no difference between the groups in the global oxygen transport parameters. Low-dose dopexamine increases PtissO2 on the serosal side of the small bowel (deltaPtissO2, 17+/-24 mm Hg in group A vs. -5+/-10 in group B). The changes in PtissO2 at the serosal side of the colon after dopexamine demonstrated a nonsignificant increase (deltaPtissO2, 7+/-11 mm Hg in group A vs. -11+/-23 mm Hg in group B). In both groups, the Pco2 gap (group A, 6+/-7 mm Hg [T1] and 5+/-6 mm Hg [T2], vs. group B, 9+/-10 mm Hg [T1] and 12+/-10 mm Hg [T2]) remained unchanged compared with the baseline. CONCLUSION: It is concluded that low-dose dopexamine improves PtissO2 at the serosal side of the gut, preferably at the small bowel. However, low-dose dopexamine did not improve gastric PmucCO2.

[The effects of dopexamine. Transpulmonary shunt volume in thoracic surgical procedures with one-lung respiration]. / Auswirkungen von Dopexamin. Transpulmonales Shuntvolumen bei thorax-chirurgischen Eingriffen mit Ein-Lungen-Beatmung.

OBJECTIVE: To study the influence of dopexamine on pulmonary shunt and hypoxic pulmonary vasoconstriction during major thoracic surgery with one-lung ventilation (OLV). DESIGN: Prospective, randomised, placebo-controlled study. SETTING: University hospital. PATIENTS: Twenty adult patients undergoing elective pulmonary resection. ANAESTHESIA: General anaesthesia was performed using propofol, fentanyl, N2O and vecuronium. Volume-controlled ventilation was performed to maintain normocapnia over the whole investigation period. During OLV, the tidal volume was reduced and the respiratory rate was increased to avoid a peak airway pressure exceeding 40 cm H2O. Furthermore the FiO2 was increased to 1.0 and the external PEEP was removed during OLV. INTERVENTIONS: The patients received either dopexamine at 2 micrograms/kg/min (group A, n = 10) or 0.9% saline as control (group B, n = 10) after assessing the baseline values. MEASUREMENT AND RESULTS: The following cardiorespiratory variables were recorded: Heart rate, mean arterial pressure and mean pulmonary arterial pressure. Cardiac output was measured by thermodilution using a continuous cardiac output thermodilution catheter. Arterial and mixed venous blood gas analysis were measured from simultaneously drawn samples. Cardiac index (CI), systemic vascular resistance index, pulmonary vascular resistance index, oxygen delivery index (DO2I), oxygen consumption index and the venous admixture were calculated using standard formula. Furthermore, pressure-flow-curves were constructed to analyse flow independent changes in the pulmonary vascular resistance. Data were recorded at the following times: After induction of anaesthesia in stable haemodynamics during two-lung ventilation (baseline values, T0), intraoperatively during one-lung ventilation (T1) and postoperatively after re-establishing two-lung ventilation (T2). Patients characteristics, data from the preoperative lung function testing and surgical procedures did not differ significantly between the groups. CI increased in the dopexamine group from 2.5 +/- 1.2 1.min-1.m-2 (T0) to 3.6 +/- 0.9 l.min-1.m-2 (T1) and 4.0 +/- 1.3 l.min-1.m-2 (T2). The course of the intrapulmonary right-to-left shunting did not differ between the groups. In the dopexamine-treated group the DO2I increased from 430 +/- 143 ml.min.m-2 (T0) to 652 +/- 255 ml.min.m-2 (T1) and 653 +/- 207 ml.min.m-2 (T2). Regarding the pressure-flow-curves there was no difference during OLV between the two groups indicating no major blocking effect of dopexamine on hypoxic pulmonary vasoconstriction. CONCLUSION: It is concluded that dopexamine can be used to improve haemodynamics and oxygen delivery during thoracic surgery without increasing venous admixture during one-lung ventilation.

Value of body plethysmography in preoperative assessment of thoracotomy candidates.

The usefulness of body plethysmography in the assessment of thoracotomy candidates is not well documented. Reported thresholds for operability are generally expressed in absolute values, which do not take into account a patient's size, age or gender. Spirometric and plethysmographic data of 103 patients undergoing thoracotomy were examined for their ability to predict death due to cardiopulmonary insufficiency, pneumonia, and atelectasis during the first 30 postoperative days. Neither plethysmographic nor spirometric parameters could predict atelectasis. Patients who underwent lobectomy were susceptible to the development of atelectasis. A weak correlation between elevated functional residual capacity (FRC) and occurrence of postoperative pneumonia was found. Lung function testing was not able to separate survivors from non-survivors. Patients with pneumonia were at high risk of death in their postoperative course. Because of the non-linear relationship, a correlation coefficient between spirometric and plethysmographic variables was not calculated. The prevalence of cardiac risk factors was high, so the decision for invasive hemodynamic studies should rather be based upon a patient's history than restricted to patients with impaired lung function. Because of methodological differences, and probably insuitable reference values, body plethysmography cannot substitute for spirometry. For FRC and FRC to total lung capacity (FRC/ TLC) ratio, further investigations must be undertaken to establish a correct reference value.

[Effects of lumbar peridural anesthesia on tissue pO2 of the large intestine in man]. / Einflüsse der lumbalen Periduralanästhesie auf den Gewebe-PO2 des Dickdarms beim Menschen.

AIM: The aim of this study was to investigate the effect of 15 ml bupivacaine 0.25%, given via an epidural catheter, on the tissue-PO2 of the colon wall in humans. METHODS: Nine patients were studied during elective colorectal surgery. The tissue-PO2 was measured by polarography, using a multiwire surface probe. RESULTS: There was no significant change in cardiac index and arterial oxygen delivery after the injection of bupivacaine. At the serosal side of the colon wall the tissue-PO2 increased from 34 to 51 mmHg after epidural bupivacaine, which is statistically significant. Spinal nerve block produces sympathetic denervation of the bowel with an increase of regional nutritive blood flow. CONCLUSION: It is concluded that epidural bupivacaine has a favourable effect on tissue oxygenation of the colon during colorectal surgery.

[Accidental anesthetic overdose caused by anesthesia respirators Servo 900 C and D]. / Unbeabsichtigte Narkosegasüberdosierung bei den Naroserespiratoren Servo 900 C und D.

When working with the anaesthetics vaporizers/respirators of the type Siemens Servo 900 C/D we found differences between the values adjusted at the instrument and those measured by the anaesthetic gas monitor (Sirecust 734 G). Control measurements yielded differences of inspiratory concentrations of halothane and isoflurane that were in excess by up to 80%. We found that the reason for this was the absence of reducing valves at the respirator that would reduce the static pressure of central gas supply from 5.3-5.5 bar to the values of not more than 4.0 bar that are permissible for the vaporizer. It is pointed out that the operation of respirators of this type is safe only provided the prescribed gas supply pressures are observed, if necessary with the help of the appropriate reducing valves, to ensure accurate dosage of volatile anaesthetics.

[Structure and organization of ambulatory and day treatment in a university clinic]. / Struktur und Organisation der ambulanten und tagesstationären Behandlung in einer Universitätsklinik.

Massive increases in costs of health care on one hand and the development of "minimal invasive" surgical techniques on the other hand have enforced an ambulatory or "day-care" treatment policy. Yet, the involvement of hospitals in ambulatory treatment has been limited in Germany, but in the near future this situation will change. In a small number of major hospitals, day surgery programs are going to be established even for infants or for patients at risk for prolonged postoperative monitoring or hospitalization. For these patients the concept of "same day surgery" is suitable. It includes ambulatory anesthesia and operation with the possibility of hospital stay, if necessary. The actual concept at the Justus-Liebig-University Giessen is described. This (at least in Germany) new approach to ambulatory operative treatment decreases costs of health care, improves the chances of hospitals in competition with private practitioners and last not least improves the status of the ambulatory compared with the hospitalized patient.

[Volume substitution in acute normovolemic hemodilution. 5% human albumin vs. 6% hydroxyethyl starch]. / Volumensubstitution während akuter normovolämischer Hämodilution (ANH). Humanalbumin 5% vs. Hydroxyäthylstärke 6%.

In order to ascertain the hemodynamic and biochemic effect of different colloid solutions, 60 patients scheduled for hip arthroplasty were randomly divided into two groups. Prior to surgery, acute normovolemic hemodilution was performed by withdrawal of 15 ml blood/kg bodyweight and simultaneous compensation using either 5% human albumine (HA) or 6% hydroxyethylstarch (200/0.5) (HAES), each group consisting of 30 patients. During and after the operation a decrease of hemoglobin-levels to 8 g% was accepted before autologous plus (if necessary) homologous blood was applied. Neither hemodilution nor tolerance of normovolemic anemia during the intra- and postoperative period had any negative effects on clinical course. Hemodynamics kept stable, no disorders of coagulation were observed. In addition lactate levels as well as histamin values remained within normal range during the whole investigation period (until the 10th postoperative day). There were no significant differences between the two groups; only histamine levels after albumin were up to 2.2 as high as after HAES. Colloid consumption at the day of operation was on the average 2.6 l/patient x day (HAES) and 3.11 (albumin) respectively. Colloidosmotic pressure remained constant in both groups and seemed to be independent from the kind of volume therapy. The present data demonstrate that normovolemic anemia can be tolerated during the perioperative period even when large amounts of colloid infusion are applied. HAES is an less expensive but adequate colloid solution compared to albumin.

Effects of hypothermia on somatosensory evoked responses in man.

Somatosensory evoked responses after median nerve stimulation were recorded in 21 patients during hypothermic cardiopulmonary bypass. During hypothermia a significant linear correlation (P less than 0.001) was found between evoked potential latency and temperature. Correlation was best for tympanic membrane temperature during cooling and for perfusate temperature (arterial, venous) during rewarming. The increase in latency was more pronounced for middle latency components (N2, N3) and for the early cortical N1 than for the cervical N0 and central conduction time. In all patients N1 was detectable at 26 degrees C, with slightly reduced amplitude. In the rewarming period the changes occurred in the reverse order and pre-bypass values were achieved at normothermia. The slopes of the regression lines were different during cooling and rewarming, when latencies were related to patient (tympanic, nasopharyngeal, rectal) temperature, but identical when arterial or venous blood temperature was used as the reference. No correlation was found between latency and perfusion pressure. We conclude that sophisticated temperature measurement is required to aid the interpretation of evoked responses used during hypothermia.