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PubMed1985

Clinical anaesthesia in the horse: comparison of enflurane and halothane.

Anaesthesia was induced in 24 horses with xylazine and ketamine and maintained with halothane (12 cases) or enflurane (12 cases) in oxygen. Pulse rate, arterial blood pressure, arterial blood gas values, respiratory rate and tidal volume were measured at regular intervals during anaesthesia. Serial venous blood samples were taken for assay of glucose, urea, haemoglobin, packed cell volume, gamma glutamyl transpeptidase, aspartate aminotransferase, alanine aminotransferase and creatine kinase. Operating conditions and the horses' behaviour in the recovery period were also recorded. In the case of the group of horses receiving enflurane, difficulty was experienced maintaining anaesthesia deep enough for surgery. This group also displayed greater respiratory depression. There were no significant differences between arterial blood pressure values, or any of the haematological or biochemical parameters recorded in each group. Recovery from anaesthesia was significantly faster in horses receiving enflurane but less smooth. It was concluded that, although enflurane appeared to be safe in the horse, the respiratory depression and the unpleasant recovery did not make it a desirable alternative to halothane.

Anesthesia, Inhalation↗
PubMed1981

[Experimental and clinical study of the biliary elimination of mezlocillin (author's transl)].

The biliary elimination of mezlocillin was studied in 5 perfused rabbit liver preparations. After adding 10 mg of mezlocillin to the perfusion medium, the biliary peak averaged 758 +/- 129 microgram/ml and total mezlocillin recovery within 3hr amounted to 20.3% of the administered dose. In 5 healthy subjects, the mean levels in the duodenal fluid collected during the 4 hrs following an infusion of 5 g of mezlocillin ranged from 440 to 637 microgram/ml. In cholecystectomized patients provided with a T-tube drainage, the maximal concentration after the same dosage (n = 10) was 505 +/- 158 microgram/ml and cumulative biliary excretion of mezlocillin over a 12 hr period corresponded to 1.3% of the administered dose. Under the same conditions, after intra-muscular injection of 1 g of mezlocillin to 10 subjects, the biliary peak averaged 292 +/- 58 microgram/ml and the total biliary recovery 2.6% of the administered dose. In 10 patients undergoing biliary tract surgery, the levels determined 1 hr after IV injection of 2 g of mezlocillin reached 896 +/- 196 microgram/ml and 402 +/- 133 microgram/ml in the main duct and in the gallbladder bile, respectively. These results were compared with the values obtained under identical conditions with 12 other beta-lactam antibiotics.

Animals↗
PubMed1992

Circulating endotoxin and tumor necrosis factor during pediatric cardiac surgery.

OBJECTIVES: To study the hypothesis that endotoxin and tumor necrosis factor-alpha (TNF) are released into the circulation during the perioperative period in children undergoing open-heart surgery, and to assess the possible role of these factors in postoperative morbidity. DESIGN: Prospective study. SETTING: Operating room and ICU of a children's hospital. PATIENTS: Twenty-four consecutive patients undergoing open-heart surgery for repair of congenital heart disease. METHODS: Endotoxin and TNF concentrations were measured in blood samples withdrawn from patients at predetermined time points in the perioperative period. These concentrations were also measured in samples from all fluids and drugs administered to patients. Clinical variables were measured throughout the perioperative period, and the Pediatric Risk of Mortality score was calculated daily. RESULTS: All of the preoperative control samples were negative for endotoxin and TNF. Endotoxin or TNF was detected in the blood of 21 (88%) of 24 patients during or after surgery. Endotoxin (ranging in concentrations from 0.32 to 438 pg/mL) was detected in the blood of 16 (67%) of the 24 patients. The majority of the samples positive for endotoxin were withdrawn during cardiopulmonary bypass and were associated with positive samples from the pump, from cardiotomy suction specimens, and from autotransfused blood. Blood cultures of all patients, except one, were negative for bacterial growth. TNF (ranging in concentrations from 3 to 132 U/mL) was detected in the blood of nine (37%) of the 24 patients. Patients positive for TNF had significantly (p less than .05) lower mean central venous pressures at 20 hrs after surgery and higher mean heart rates postoperatively compared with patients negative for TNF. No differences in other indicators of perioperative morbidity and intraoperative conditions were found, when the groups positive for endotoxin or TNF were compared with the groups negative for endotoxin or TNF, respectively. CONCLUSIONS: Endotoxin and TNF are released into the circulation during and after pediatric open-heart surgery. TNF release may be related to some of the hemodynamic changes observed after open-heart surgery.

Child↗
PubMed2000

Endotoxemia during supraceliac aortic crossclamping is associated with suppression of the monocyte CD14 mechanism: possible role of transforming growth factor-beta1.

PURPOSE: Monocyte CD14 and its soluble form (sCD14) mediate the proinflammatory response to endotoxemia. The aim of this study was to measure the changes to these factors after major aortic surgery and the possible inhibitory role of transforming growth factor-beta(1) (TGF-beta(1)) during these procedures. METHODS: Twenty-four patients with supraceliac aortic crossclamping during thoracoabdominal aortic aneurysm (TAAA) repair and 12 patients with infrarenal aortic crossclamping as part of infrarenal aneurysm repair (AAA) were studied. Blood was collected at incision, aortic clamping, and reperfusion and at 1, 8, and 24 hours after reperfusion. Samples were assayed for endotoxin, peripheral blood monocyte CD14 expression, sCD14, tumor necrosis factor-alpha, and TGF-beta(1). RESULTS: Although there was significant endotoxemia on reperfusion in both groups of patients, peak plasma endotoxin levels were significantly higher in patients with TAAA (P =.001). Monocyte CD14 and plasma sCD14 were significantly decreased in patients with TAAA at reperfusion and 1 hour after reperfusion (P <.01, both points). In patients with AAA, a significant upregulation of CD14 was observed at 24 hours after reperfusion (P <.01), but no significant changes in sCD14 were observed. TNF-alpha showed no significant changes during the study period in both groups. In patients with TAAA, TGF-beta(1) showed significant elevation at all time points (P <.01); whereas in patients with AAA, TGF-beta(1) showed no significant changes. CONCLUSION: Splanchnic ischemia reperfusion in patients who undergo supraceliac aortic clamping is associated with peripheral blood monocyte CD14 suppression and significant elevation of TGF-beta(1). TGF-beta(1) may play an important role in modulating the immune response to endotoxemia during major aortic aneurysm surgery.

Aged↗
PubMed1983

Activated coagulation and activated partial thromboplastin times in assessment and reversal of heparin-induced anticoagulation for cardiopulmonary bypass.

In 22 adult patients, activated coagulation times (ACT) were compared to activated partial thromboplastin times (aPTT) before, during, and after cardiopulmonary (CP) bypass surgery. After intravenous heparin (150 units/kg), mean ACT increased from 131 +/- 14 (mean +/- SD) to 362 +/- 72 s (P less than 0.001). With 1.5 units of heparin/ml added to the priming solution of the pump, ACT ranged from 230 to 541 s and aPTT was always 300 s or longer. Activated PTT appears to be less sensitive to changing plasma heparin levels than ACT. Heparin neutralization with a protamine/heparin ratio of 1.0 returned ACT and aPTT to preheparin levels. No abnormal bleeding tendency was seen during the recovery period, and ACT and aPTT remained at preheparin levels. In 10 infants and children undergoing open-heart surgery, ACT was measured in response to the same heparin and protamine regimen. Baseline (113 +/- 14 s) and post-heparin (297 +/- 90 s) ACT were shorter in children than in adults (P less than 0.01). After protamine, ACT was still longer than baseline (134 v 113 s, P less than 0.05). Infants and children seem to require more heparin/kg body weight than adults to achieve comparable ACT levels.

Aged↗
PubMed1990

Effects of enflurane and isoflurane in air-oxygen on changes in thermal balance during and after surgery.

The temperatures in the aural canal (core), skeletal muscle and skin surface were measured during anaesthesia and surgery in 32 healthy females undergoing total abdominal hysterectomy and for 4 h after operation. The patients were allocated randomly to one of four groups according to the end-tidal concentration of volatile anaesthetic: 1 MAC isoflurane, 1 MAC enflurane, 1.8 MAC isoflurane and 1.8 MAC enflurane. The lungs were ventilated with an air-oxygen mixture. Neuromuscular block was produced with pancuronium. Room temperature and i.v. fluid administration were standardized. Aural canal, muscle and mean skin temperatures decreased significantly in all groups during surgery (P less than 0.001). The decrease in core and muscle temperatures, and mean body heat was significantly greater in the 1.8 MAC groups than in the 1 MAC groups for both volatile agents (P less than 0.001). However, there was a significantly greater decrease in core temperature and mean body heat in the isoflurane compared with the enflurane group (P less than 0.026). Body temperature returned to preoperative values during the recovery period. There was a significantly greater rate of rewarming during the first 1 h of recovery in the 1.8 MAC groups compared with the 1 MAC equivalent (P less than 0.001), and this was independent of the volatile agent used. The present results are compared with those reported previously in which nitrous oxide was added to the volatile agents. The decrease in body temperature depends upon the concentration of vapour used. However, it appears that isoflurane, without nitrous oxide, caused greater loss of body heat than enflurane.

Adult↗
PubMed1985

[Cardiovascular adaptability to acute hypercalcemia in the dog. The role of peroperative myocardial ischemia].

Since the hemodynamic consequences of acute hypercalcemia are altered by numerous interferences we have evaluated the role of peroperative myocardial ischemia on the adaptability to rapid calcium increment. Twenty-two dogs served as control and 16 were submitted to 1 hour of myocardial ischemia along with topical myocardial cooling. Each animal was equipped with blood flow transducer positioned around the ascending aorta and with central venous and aortic catheters. During each study 0.90 mEq of calcium was rapidly injected and hemodynamic data were recorded until base-line resetting. This experimental protocol was carried out 3 hours postoperatively and then daily during one month. Base-line hemodynamic data indicated the presence of myocardial failure in the experimental group in the immediate postoperative period only. Rapid calcium administration elicited transient positive inotropic response, widening of the arterial pulse pressure, reflex bradycardia and no evidence of peripheral vasoconstriction. In the early postoperative period (3 hours after surgery) the failing myocardium is more sensitive to the inotropic effect of hypercalcemia. Twenty-four hours after surgery both groups of animals have the same hemodynamic response to this stress; thereafter for both groups this response gradually decreased and finally stabilized by the 6th to 10th day after surgery. Acute hypercalcemia bears hemodynamic consequences that are amplified early after peroperative myocardial ischemia. However in long term this surgical component widely used clinically does not interfered with the cardiovascular adaptability to this pharmacological stress.

Acid-Base Equilibrium↗
PubMed1984

[Hemodynamics and changes in compliance of the extra-thoracic capacity system following administration of prostacyclin (PGI2)].

Hemodynamic effects of prostacyclin (PGI2) given as an intravenous infusion at a rate of 8 ng/kg/min were assessed in 50 patients with coronary artery disease at the time of aortocoronary bypass surgery. 1. During steady-state neuroleptic anesthesia, after sternotomy and pericardiotomy, before cannulation of the aorta and vena cava PGI2 led to the following changes: decreases in mean arterial pressure (-24%), total peripheral resistance (-46%), left ventricular pressure (-12%) and left ventricular end-diastolic pressure (-48%), increases in heart rate (+9%), cardiac output (+41%), stroke volume (+30%) and dp/dtmax (+26%) as well as nonsignificant decreases in right ventricular filling pressure (-13%) and mean pulmonary arterial pressure (-9%) together with an unaltered rate-pressure product. 2. In a randomized double-blind study PGI2 was infused throughout the period from two minutes prior to, until termination of extracorporeal circulation. The effects on compliance of the extrathoracic venous system were analyzed on the basis of changes in venous pressure and oxygenator volume. As compared with controls, patients receiving PGI2 were found to have a significant increase in compliance (.157 ml/mm Hg X kg). Thus, in this setting, PGI2 can affect marked vasodilatation with reductions in peripheral resistance and mean arterial pressure together with increases in cardiac output and heart rate.

Clinical Trials as Topic↗
PubMed1986

Esmolol and the adrenergic response to perioperative stimuli.

Esmolol, an ultra-short-acting, cardioselective, beta-receptor blocking agent, has been developed for use in clinical conditions requiring controlled beta-receptor blockade. Its esterase-induced rapid metabolic inactivation and resulting brief pharmacologic effect provides control over the magnitude and duration of beta-receptor blockade. In placebo-controlled clinical trials, the effects of infusion of esmolol on the sympathetically mediated hemodynamic responses to stressful events during the perioperative period were evaluated in patients scheduled for surgical procedures under general anesthesia. In patients undergoing either noncardiac or cardiac surgical procedures, esmolol was effective in attenuating tachycardia that is normally seen during induction of anesthesia, laryngoscopy and endotracheal intubation, or sternotomy and aortic dissection by reducing the hemodynamic stress on the heart with negligible adverse effects. This much-desired cardioprotective effect of esmolol will be of special value to patients with coronary artery disease and patients with an unstable cardiovascular status who are undergoing major surgical procedures with general anesthesia.

Adrenergic beta-Antagonists↗
PubMed2006

Intradural lumbar disc herniation--is it predictable preoperatively? A report of two cases.

BACKGROUND CONTEXT: Intradural disc herniations are thought to be rare events, and there have been relatively few literature reports of intradural disc herniations available with regard to magnetic resonance imaging findings. PURPOSE: The authors describe two patients with intradural lumbar disc herniations, one with and one without preoperative diagnosis, who had different postoperative outcomes. STUDY DESIGN: Case study METHODS: The first patient underwent an extended L3 subtotal laminectomy followed by bilateral medial facetectomy and foraminotomy at L3-L4. A durotomy uncovered large disc fragments comprised of friable disc materials and end plates, after no clear disc herniation was found in the epidural space. The second patient underwent anterior lumbar interbody fusion after a preoperative diagnosis of intradural disc herniation. RESULTS: The first patient experienced a marked reduction of pain and progressive recovery of sensory disturbance, but neurologic examination showed right foot drop postoperatively. Two years after surgery, she can not walk without a cane because the neurologic deficit of the right ankle has shown no improvement. Two days after surgery, the second patient was allowed to ambulate with a lumbar orthosis. Neurologic examination showed no motor deficit. Twenty-one months after surgery, the patient reports minimal back pain when sitting on a chair for prolonged periods of time. CONCLUSION: Our cases highlight the importance of preoperative diagnosis in the treatment of intradural lumbar disc herniations. The potential presence of an intradural disc herniation must always be considered preoperatively on a patient whose magnetic resonance imaging study demonstrates the "hawk-beak sign" on axial imaging as well as abrupt loss of continuity of the posterior longitudinal ligament (PLL). This association results in an adequate surgical approach, thereby reducing the chance of postoperative neurologic deficit. Finally, anterior lumbar interbody fusion can be a reasonable alternative in the treatment of intradural lumbar disc herniations.

Adult↗
PubMed2000

Humoral immune response during coronary artery bypass grafting: A comparison of limited approach, "off-pump" technique, and conventional cardiopulmonary bypass.

BACKGROUND: The introduction of limited approaches to the heart and the avoidance of cardiopulmonary bypass (CPB) aim to reduce the invasiveness of CABG by decreasing the systemic release of inflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8, as well as the anti-inflammatory agent IL-10. This study compares the humoral immune response in patients undergoing CABG with standard, minimally invasive, and "off-pump" techniques. METHODS AND RESULTS: Thirty patients were divided into 3 operative groups: full sternotomy approach plus CPB (group A); full sternotomy approach, off pump (group B); and limited left anterior thoracotomy, off pump (group C). Plasma levels of TNF-alpha receptors p55 and p75, IL 6, IL-8, and IL-10 were taken at baseline, during CPB, and at 4, 24, and 48 hours and 6 days after surgery. A significant increased release of activated complement factors C5a and C3d, IL-8, and IL-10 was observed in patients subjected to CPB (group A) during the initial period and for a short time after perfusion (P:<0.05). TNF-alpha receptors p55 and p75 showed a prolonged elevation (up to 48 hours) in the CPB group compared with the 2 off-pump groups. IL-6 showed no different release among the 3 surgical groups throughout the entire period. There was no significant difference in any parameter measured in relation to the type of operative approach. CONCLUSIONS: There is an inflammatory, as well as an anti-inflammatory, response during CABG that is related to the general surgical trauma. The release of immune mediators is enhanced by the use of CPB during various perioperative and postoperative phases. The type of operative approach did not influence this immune response.

Aged↗
PubMed2003

Laparoscopic extraperitoneal approach to acutely incarcerated inguinal hernia.

BACKGROUND: Laparoscopic treatment of acutely incarcerated inguinal hernia is uncommon and still controversial. Those being performed almost all use the transabdominal (TAPP) approach. The authors here present their experience with totally extraperitoneal (TEP) repair of acutely incarcerated hernia. METHODS: A retrospective review was undertaken to evaluate the authors' experience with this procedure over a 4-year period. There were 16 cases, 5 of which were performed using a conventional anterior repair. These 5 cases were excluded from the review. The surgery for all of the remaining 11 acutely incarcerated hernias was started laparoscopically using the TEP approach. Eight of the cases were completed this way, whereas three were converted to the open procedure. In addition to standard TEP repair techniques, a releasing incision is required for acutely incarcerated direct, indirect, or femoral hernias. With a direct hernia, the opening of the defect is enlarged to allow safe dissection of its contents. A releasing incision is made at the anteromedial aspect of the defect to avoid injury to the epigastric or iliac vessels. With an indirect hernia, several additional steps are required. The epigastric vessels may be divided; an additional trocar may be placed laterally below the linea semicircularis to facilitate dissection of the sac and to assist with suturing of the divided sac; and the deep internal ring is divided anteriorly at the 12 o'clock position toward the external ring, facilitating dissection of the indirect sac. With a femoral hernia, a releasing incision is made by carefully incising the insertion of the iliopubic tract into Cooper's ligament at the medial portion of the femoral ring. RESULTS: The mean operative time was 50 min (range, 20-120 min), and the length of hospital stay was 5.4 days (range, 1-29 days). During a follow-up period of 9 to 69 months, there was no recurrence, and only two complications. One of these complications was an infected mesh that occurred in a case involving cecal injury. It was treated with continuous irrigation and salvaged. The other complication was a midline wound infection after a small bowel resection for a strangulated obturator hernia. CONCLUSIONS: Familiarity with the anatomy involved leads to the conclusion that the laparoscopic approach, specifically the TEP procedure, can be used without hesitation even in cases of acutely incarcerated hernia.

Acute Disease↗
PubMed1985

Plasma magnesium during epidural anaesthesia. A study in patients undergoing transurethral prostatectomy.

The variations of plasma magnesium concentration in relation to protein concentration and plasma volume were studied in 12 patients during epidural anaesthesia for transurethral prostatectomy. The most significant changes in plasma magnesium concentration were observed during the onset of anaesthesia. From the arrival in the operating theatre to the start of operation, the concentration of plasma magnesium decreased from 0.88 (SD 0.10) mmol/l to 0.82 (SD 0.10) mmol/l. At the same time, the increase of 16 per cent in plasma volume was associated with a rise of 8.4 per cent in the total amount of magnesium in plasma. After commencement of surgery, the plasma magnesium concentration was unchanged throughout the remainder of the study period. The total plasma protein concentration and the erythrocyte volume fraction decreased during the onset of anaesthesia, remained stable during surgery and returned to initial values one hour postoperatively. The pre-operative changes in the plasma magnesium concentration may have been the result of haemodilution and mobilisation of magnesium ion from its bone stores. Postoperatively, an increased urinary loss of magnesium must have followed the injection of frusemide at the end of surgery. The consequences of these variations in plasma magnesium concentration are unlikely to be of clinical significance, except in patients with pre-existing subclinical magnesium deficiency.

Aged↗
PubMed1997

[The effects of dopexamine. Transpulmonary shunt volume in thoracic surgical procedures with one-lung respiration].

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.

Aged↗
PubMed2002

The rate of instrument breakage during orthopaedic procedures.

The current study investigates instrument breakages during both emergency and elective orthopaedic surgery. Over a 2 year period a total of 7,775 procedures were performed. We found that 14 instruments were broken during 12 operative cases. Drill bits accounted for the largest proportion of breakages (11/14), and a specialist registrar was the lead surgeon in the majority (8/12) of cases. Only one case had a consultant as the lead surgeon. In seven cases the broken bit of the surgical instrument was left in the patient. Documentation of this peri-operative complication was deficient, and the patient was often not informed.

Adolescent↗
PubMed1982

Haemodynamic and plasma vasopressin responses with high-dose fentanyl anaesthesia during aorto-coronary bypass operations.

Twelve male patients were given high dose fentanyl (75-100 microgram.kg-1) anaesthesia with oxygen during elective aorto-coronary bypass operations, and their haemodynamic and vasopressin responses were determined during induction, sternotomy, cardiopulmonary bypass, post-bypass and recovery periods. For comparison, a group of 12 male patients were anaesthetized with morphine, halothane 0.5 per cent, nitrous oxide and oxygen, and were similarly studied. Significant alterations in haemodynamics included increased mean arterial pressure after sternotomy in the fentanyl group, increased heart rate in both groups, increased systemic vascular resistance after sternotomy only in the halothane group, and decreased left ventricular stroke work index in both groups following induction, bypass, and during the recovery periods. Plasma vasopressin levels increased significantly in both groups during the bypass period, but returned to baseline levels following bypass. Serum sodium and osmolality did not change significantly, and urinary sodium and potassium excretion rose with the progress of the operation in both groups. A positive correlation was found between mean arterial pressure and vasopressin only in the halothane group. Systemic vascular resistance was correlated to vasopressin levels in both groups. Vasopressin response in both groups was similar, with significant but relatively low increases in levels during cardiopulmonary bypass. Fentanyl-oxygen anaesthesia did not provide haemodynamic stability in eight of 12 patients.

Adult↗
PubMed1997

Intra-operative gas exchange and post-operative hypoxaemia.

The relation between intra-operative gas exchange and post-operative oxygen saturation was examined using pulse oximetry (SpO2) 30 h after anaesthesia for upper abdominal surgery. The inspired oxygen partial pressure (PIO2) was varied during anaesthesia to produce a plot of PIO2 vs. SpO2. Gas exchange during anaesthesia was inferred from the relation between PIO2 and SpO2 which was described by its lateral and vertical displacement away from the position of a standard oxygen dissociation curve. With patients breathing air, the SpO2 was measured over a 10-min period at 30 h after surgery. The correlation coefficient of the lateral displacement with post-operative SpO2 was 0.7, and that of the vertical displacement with post-operative SpO2 was 0.66. The correlation coefficient of intra-operative SpO2 at PIO2 = 21 kPa with post-operative SpO2 was 0.69. It can be concluded that gas exchange abnormalities during anaesthesia deduced from the displacement of the PIO2 vs. SpO2 curve correlate with SpO2 30 h post-operatively and may help to identify patients at risk of post-operative hypoxaemia.

Abdomen↗
PubMed1983

Atrio-ventricular and ventriculo-atrial conduction times in patients undergoing pacemaker implant.

Pacemaker mediated reentrant tachycardias have been seen frequently during use of dual chamber sensing pacemakers and are dependent on the presence of intact retrograde (ventriculo-atrial) conduction. The status of a patient's retrograde (VA) conduction cannot be determined from the surface electrocardiogram. At the time of pacemaker implant the state of antegrade conduction should be determined at incremental atrial pacing rates, the exact timing measured from the intracardiac electrograms, i.e., from the intrinsic deflection of the intrinsic deflection of the ventricle. With this information obtained in 53 patients, it was possible to determine which patients could safely receive dual chamber sensing pacemaker devices, the appropriate pacemaker atrial refractory period setting to avoid pacemaker mediated tachycardias in those patients with intact retrograde conduction, and the optimal timing for programming the pacemaker's AV delay. Patients who have been studied in this manner and who were felt to be suitable for a dual chamber sensing device have not displayed pacemaker mediated reentrant tachycardias. Forty-seven percent of all patients who require pacemaker implant have VA 1:1 conduction; 67% of those with sinus node dysfunction and 14% of those with complete antegrade block have VA conduction at a mean interval of 235 +/- 50 ms (range 110-380 ms).

Atrioventricular Node↗