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Biomedical subjects

A A d'Hollander

Publications and source records attributed to A A d'Hollander.

At least 19 recordsLinked to original sources
PubMed2005

The quantitative distinction between train-of-four "counts of 2" and posttetanic "counts of 2" evidenced by a stable paralysis/stable infusion rate method in anesthetized patients receiving mivacurium.

In this study we quantitatively evaluated, by a stable paralysis/stable infusion rate method, the difference between two standardized paralysis levels--train-of-four (TOF) count of 2 responses and posttetanic count (PTC) of 2. Ten ASA physical status I-II consenting adult patients scheduled for elective surgery were anesthetized (sufentanil/propofol), tracheally intubated, mechanically normoventilated with a fixed O(2)/air mixture, and normothermic; oropharynx and thenar temperatures were maintained above 36 degrees and 32.5 degrees C, respectively. After partial recovery from 200 microg/kg mivacurium (MIV), stable tactile TOF and PTC counts of 2 paralysis levels were induced on the adductor pollicis muscle by manual adjustments of an infusion pump containing MIV. The paralysis levels and the infusion rates were considered as stable once they remained constant at 4 consecutive time points separated by 5 min each. Infusion rates observed were: TOF count 2-6 (2-11) and PTC 2-17 (3-18) microg . kg(-1) . min(-1) (P < 0.001; Wilcoxon's paired comparison test). Under the present conditions, obtaining and maintaining a PTC of 2 requires MIV infusion rates far in excess of the "standard" recommendations mentioned in the literature for MIV infusion management.

Adult↗
PubMed2002

Intrinsic positive end-expiratory pressure during one-lung ventilation of patients with pulmonary hyperinflation. Influence of low respiratory rate with unchanged minute volume.

BACKGROUND: We measured lung mechanics and gas exchange during one-lung ventilation (OLV) of patients with chronic obstructive pulmonary disease, using three respiratory rates (RR) and unchanged minute volume. METHODS: We studied 15 patients about to undergo lung surgery, during anaesthesia, and placed in the lateral position. Ventilation was with constant minute volume, inspiratory flow and FIO2. For periods of 15 min, RR of 5, 10, and 15 bpm were applied in a random sequence and recordings were made of lung mechanics and an arterial blood gas sample was taken. Data were analysed with the repeated measures ANOVA and paired t-test with Bonferroni correction. RESULTS: PaO2 changes were not significant. At the lowest RR, PaCO2 decreased (from 42 (SD 4) mm Hg at RR 15-41 (4) mm Hg at RR 10 and 39 (4) mm Hg at RR 5, P<0.01), and end-tidal carbon dioxide increased (from 33 (5) mm Hg at RR 15 to 35 (5) mm Hg at RR 10 and 36 (6) mm Hg at RR 5, P<0.01). Intrinsic positive end-expiratory pressure (PEEPi) was reduced even with larger tidal volumes (from 6 (4) cm H2O at RR 15-5 (4) cm H2O at RR 10, and 3 (3) cm H2O at RR 5, P<0.01), most probably caused by increased expiratory time at the lowest RR. CONCLUSION: A reduction in RR reduces PEEPi and hypercapnia during OLV in anaesthetized patients with chronic obstructive lung disease.

Aged↗
PubMed2000

Two-lung and one-lung ventilation in patients with chronic obstructive pulmonary disease: the effects of position and F(IO)2.

UNLABELLED: We compared the effects of position and fraction of inspired oxygen (F(IO)2) on oxygenation during thoracic surgery in 24 consenting patients randomly assigned to receive an F(IO)2 of 0.4 (eight patients, Group 0.4), 0.6 (eight patients, Group 0.6), or 1.0 (eight patients, Group 1.0) during the periods of two-lung (TLV) and one-lung ventilation (OLV) in the supine and lateral positions. TLV and OLV were maintained while the patients were first in the supine and then in the lateral position for 15 min each. Thereafter, respiratory mechanical data were obtained, and arterial blood gas samples were drawn. Pao2 decreased during OLV compared with TLV in both the supine and lateral positions. In all three groups, Pao2 was significantly higher during OLV in the lateral than in the supine position: 101 (72-201) vs 63 (57-144) mm Hg in Group 0.4; 268 (162-311) vs 155 (114-235) mm Hg in Group 0.6; and 486 (288-563) vs 301 (216-422) mm Hg in Group 1.0, respectively (P < 0.02, Wilcoxon's signed rank test). We conclude that, compared with the supine position, gravity augments the redistribution of perfusion as a result of hypoxic pulmonary vasoconstriction, when patients are in the lateral position, which explains the higher Pao2 during OLV. IMPLICATIONS: This study compares oxygenation during thoracic surgery during periods of two-lung and one-lung ventilation with patients in the supine and lateral positions when using three different fraction of inspired oxygen values. Arterial oxygen tension was decreased in all three groups during one-lung ventilation in comparison with the two-lung ventilation values, but the decrease was significantly less in the lateral, compared with the supine position.

Adult↗
PubMed2000

Predictive accuracy of target-controlled propofol and sufentanil coinfusion in long-lasting surgery.

BACKGROUND: The predictive accuracy of target concentration infusions of propofol has been documented only for less than 4 h, and no prospective study of sufentanil target controlled infusion is available. The authors investigated the predictive accuracy of pharmacokinetic models for propofol and sufentanil coadministered during long-lasting surgery. METHODS: Ten patients, American Society of Anesthesiologists physical status I and II, were studied during extended cervicofacial surgery. Target controlled infusion of propofol and sufentanil was administered during surgery using decisional algorithms, taking into consideration pain assessment, hemodynamic changes, and peroperative blood losses. Intrasubject data analysis included calculation of performance error, median performance error, median absolute performance error, divergence, and wobble. RESULTS: The range of plasma target concentrations was 2-5 microgram/ml for propofol and 0.2-1 ng/ml for sufentanil. Median performance error was -12.1% for propofol and -10% for sufentanil. The wobble values were 11.6% and 22.3% for propofol and sufentanil, respectively. The pharmacokinetic sets used slightly overpredicted the concentrations, with negative values of divergence of 2.92% and 0.22% units/h for propofol and sufentanil, for a mean infusion period of 762 min. CONCLUSIONS: This prospective study demonstrates the predictive accuracy of the pharmacokinetic model for sufentanil infusion and confirms that for propofol during long-lasting surgery using standardized rules for the management of target controlled infusion and blood loss replacement.

Adult↗
PubMed1998

Respiratory mechanics and gas exchange during one-lung ventilation for thoracic surgery: the effects of end-inspiratory pause in stable COPD patients.

OBJECTIVE: To examine the effects of end-inspiratory pause (EIP) of different durations on pulmonary mechanics and gas exchange during one-lung ventilation (OLV) for thoracic surgery. DESIGN: A prospective clinical study. SETTING: A university hospital. PARTICIPANTS: Eleven patients undergoing elective pulmonary resection with pulmonary hyperinflation on their preoperative pulmonary function studies. INTERVENTIONS: Patients were anesthetized, paralyzed, and intubated with a double-lumen endotracheal tube. Their lungs were ventilated with a Siemens 900C ventilator (Siemens; Solna, Sweden), with constant inspiratory flow. Tidal volume, respiratory rate, and inspiratory time were kept constant during the study. MEASUREMENTS AND RESULTS: During one-lung ventilation in the lateral decubitus position, three levels of EIP (0%, 10%, and 30%) were applied to the dependent lung in random order. After 15 minutes on the given ventilatory pattern, end-inspiratory and end-expiratory occlusions of at least 5 seconds were performed to obtain respiratory mechanics data. Arterial blood gas samples were drawn to assess gas exchange. Altering the duration of end-inspiratory pause from 0% to 30% resulted in a significant increase in intrinsic positive end-expiratory pressure (PEEPi) from 4.1 cm H2O to 7.0 cm H2O. Arterial oxygenation was significantly decreased from 109.7 to 80.5 mmHg and there was a significant negative correlation between the value of partial pressure of arterial oxygen (PaO2) and PEEPi by altering the duration of end-inspiratory pause. From the preoperative pulmonary function studies, the value of functional residual capacity (FRC) (% predicted) showed a significant negative correlation with the PaO2 changes. Partial pressure of arterial carbon dioxide (PaCO2) was not altered significantly by increasing the duration of end-inspiratory pause. CONCLUSION: During the period of OLV in the lateral position of patients with preexisting pulmonary hyperinflation, the magnitude of PEEPi increased and oxygenation decreased significantly, whereas the efficacy of ventilation was not changed by the addition of an end-inspiratory pause to the ventilatory pattern. Because arterial oxygenation is affected by the presence of pulmonary hyperinflation, the method of ventilation should take into account the magnitude of preoperative pulmonary hyperinflation.

Aged↗
PubMed1998

Interrupted expiratory flow on automatically constructed flow-volume curves may determine the presence of intrinsic positive end-expiratory pressure during one-lung ventilation.

UNLABELLED: We studied patients undergoing elective pulmonary surgery to establish whether observing interrupted expiratory flow (IEF) on the flow-volume curves constructed by the Ultima SV respiratory monitor is a reliable way to identify patients with dynamic pulmonary hyperinflation and intrinsic positive end-expiratory pressure (PEEPi). Patients' tracheas were intubated with a double-lumen endotracheal tube and ventilated with a Siemens 900C constant flow ventilator. In 30 patients, PEEPi was determined by the end-expiratory occlusion (EEO) method during the periods of two-lung and one-lung ventilation in the lateral position. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of the IEF method were calculated. From the 122 measurement pairs, PEEPi was identified with the EEO method in 65 occasions. The mean level of PEEPi was 4.4 cm H2O. During one-lung ventilation, the level of PEEPi and the number of true-positive findings was significantly higher (PEEPi = 4.7 cm H2O and 32 episodes) than during two-lung ventilation (2.9 cm H2O and 19 episodes). When the level of PEEPi was higher than 5 cm H2O, the predictive value of IEF was 100%. The overall sensitivity of the IEF method was 0.78, its specificity was 0.91, and its predictive value was 0.92. In conclusion, examination of the flow-volume curves displayed on the respiratory monitor may identify patients with dynamic hyperinflation and PEEPi during anesthesia for thoracic surgery. IMPLICATIONS: To identify patients with intrinsic positive end-expiratory pressure during anesthesia without the need to interrupt mechanical ventilation, the flow-volume curves of an online respiratory monitor may be examined. The presence of an interrupted expiratory flow may suggest the presence of intrinsic positive end-expiratory pressure with a reasonable accuracy.

Adult↗
PubMed1998

Visual evaluation of residual curarization in anesthetized patients using one hundred-hertz, five-second tetanic stimulation at the adductor pollicis muscle.

UNLABELLED: We were looking for a clinical test to indicate a train-of-four (TOF) ratio of approximately 0.9. We compared the adductor pollicis muscle (AP) visually evaluated response to ulnar nerve 100-Hz, 5-s tetanus (RF100 Hz) with the measured AP TOF ratio in 30 ASA physical status I or II adult anesthetized (propofol, sufentanil, N2O/O2) patients. After the induction of anesthesia, the left ulnar nerve was stimulated at the wrist (single twitch and TOF) and the resultant isometric force was measured. When TOF was assessed, the independent investigators, unaware of the left AP-measured TOF ratios, visually evaluated the presence or absence of AP fading elicited by right ulnar nerve 100-Hz, 5-s tetanus. The 30 patients were randomly allocated to receive either 0.5 mg/kg atracurium (n = 15) or 0.1 mg/kg vecuronium (n = 15). The neuromuscular blockade was allowed to resolve spontaneously. A multiple logistic regression analysis was performed by computing the 771 visual observations. The probabilities of success of 100-Hz, 5-s tetanus to detect TOF ratios of 0.8, 0.85, and 0.9 were 99%, 96%, and 67%, respectively. The sensitivity and specificity of 100-Hz, 5-s tetanus as an indicator of TOF ratios of 0.85 and 0.9 are 100% and 75%, 54% and 67%, respectively. We conclude that RF100 Hz visual assessment seems to be highly sensitive in evaluating residual paralysis, as the absence of RF100 Hz visual fading at the AP is compatible with a TOF ratio > 0.85. IMPLICATIONS: After the administration of muscle relaxants, the absence of visual fading at the adductor pollicis, elicited in anesthetized patients by 100-Hz, 5-s tetanus, is compatible with a train-of four ratio > 0.85. Therefore, clinical observation of fading after 100-Hz, 5-s tetanus seems to be a highly sensitive test in evaluating residual paralysis.

Adult↗
PubMed1997

Clinical evaluation of an automatic blood pressure controller during cardiac surgery.

OBJECTIVE: During surgery, computers can be of great use to support the anesthesiologist in providing task automation. In this paper we describe a closed loop blood pressure controller and show the results of its clinical evaluation. METHODS: The controller is based on a simple and robust Proportional-Integral controller and a supervising, rule based, expert system. Adaptive control is necessary because the sensitivity of the patients to sodium nitroprusside varies over a wide range. Thirty-three clinical tests during cardiac surgery, including the cardiopulmonary bypass phase, were performed. RESULTS: On average the controller was in automatic mode for 90.6 +/- 9.6% of the time. The performance during automatic control showed the mean arterial pressure to be within 10 mmHg of the setpoint for 71.4 +/- 15.5% of the time. The average absolute distance to the setpoint was 8.1 +/- 7.2 mmHg. CONCLUSIONS: The overall performance of the controller was noted as very satisfactory by the anesthesiologists.

Algorithms↗
PubMed1997

Airway pressure changes during one-lung ventilation.

This investigation analyzed the changes in inspiratory airway pressures during transition from two-lung to one-lung ventilation in patients tracheally intubated with a double-lumen endotracheal tube (DLT) using a classical method of intubation without fiberoptic bronchoscopy. All patients were anesthetized in a standardized fashion. Ventilation was accomplished with the Siemens 900 constant-flow mechanical ventilator (Solna, Sweden). Peak (Ppeak) and plateau (Pplateau) inspiratory airway pressures were recorded with an on-line respiratory monitor before and after clamping the tracheal limb of the DLT. The position of the DLTs was evaluated by fiberoptic bronchoscopy with the patient in supine position. Of the 51 intubations, the DLT was malpositioned in 15 cases (29.5%). Ppeak and Pplateau increased significantly when switched from two-lung ventilation to one-lung ventilation in both correctly and incorrectly positioned DLTs. When the DLT was in a correct position, Ppeak increased by a mean of 55.1% and Pplateau increased by a mean of 41.9%. When the DLT was malpositioned, this increase was significantly larger (74.9% and 68.8%, respectively). Three tests commonly used as markers of malpositioned DLTs were evaluated based on the data of this study, and it was established that, although the pressure differences related to position are statistically significant, as a single value, they cannot be used for clinical decision making.

Airway Resistance↗
PubMed1996

Influence and relative sensitivities of 50-Hz and 100-Hz tetanic stimuli on subsequent tetanic fade ratios in patients receiving vecuronium.

We studied the possible effects of repetitive (1-min interval) 50- and 100-Hz tetanic stimuli on 50-Hz and 100-Hz tetanic fade ratios (RF50HZ and RF100HZ). We also evaluated the sensitivity of the recorded responses to these two tests to assess residual neuromuscular block (isometric adductor pollicis mechanical activity), either during spontaneous recovery, or 15 min after neostigmine administration, in 22 adult anesthetized (thiopental, fentanyl, N2O/O2) patients receiving vecuronium. Two 50-Hz and two 100-Hz, 5-s duration, tetanic stimulations were randomly assessed at 1-min intervals: in a spontaneous (SPO) group (n = 11), when train-of-four (TOF) ratio spontaneously regained 0.7, and in a neostigmine (NEO) group (n = 11), 15 min after 40 micrograms/kg neostigmine was given intravenously at 25% return of control twitch tension. In the SPO group, when TOF ratio was 0.7, RF50HZ was 0.92 +/- 0.01 before and after subsequent tetanic stimulation, while RF100HZ was 0.48 +/- 0.05 and 0.47 +/- 0.05, respectively (not significant [NS]). In the NEO group, when TOF ratio was approximately 0.9, RF50HZ was 0.93 +/- 0.01 before and after subsequent tetanic stimulation, while RF100HZ was 0.80 +/- 0.02 and 0.78 +/- 0.02, respectively (NS). From patient to patient, both RF50HZ and RF100HZ were also identical. In conclusion, in patients receiving vecuronium, 1) 5-s, 50- and 100-Hz tetanic stimuli may be repeated without changes at 1-min intervals and, 2) in contrast to RF50HZ, recorded RF100HZ enables one to determine residual neuromuscular block during spontaneous recovery (P < 0.001) such as after neostigmine reversal (P < 0.05).

Adolescent↗
PubMed1995

Low and high frequency stimulation tests to characterize the effects of edrophonium on vecuronium-induced neuromuscular block.

We recorded adductor pollicis mechanical activity in response to low (0.1 and 2 Hz) and high (50 and 100 Hz) frequency stimulation 15 min after edrophonium 250, 500 and 1000 micrograms kg-1, given to antagonize vecuronium-induced block at 10, 25 and 50% pre-reversal twitch height. We studied 54 ASA class I and II anaesthetized (methohexitone, fentanyl, nitrous oxide) young adult patients allocated randomly to nine groups of six patients each. The greater sensitivity of train-of four (TOF) ratio and residual force after 100-Hz, 5-s tetanic stimulation (RF100) to residual deficit allowed discrimination more readily between the effects of edrophonium dose and pre-reversal twitch height (P < 0.001, two-way analysis of variance). The highest reversal scores (approximately 0.9 TOF ratio and 0.6 RF100) were obtained when edrophonium 500-1000 mg kg-1 was given at 50% twitch height (P < 0.05, Duncan's test).

Adolescent↗
PubMed1995

Large tidal volume ventilation does not improve oxygenation in morbidly obese patients during anesthesia.

Eight morbidly obese patients (body mass index [BMI] = 46) were studied during general anesthesia and controlled mechanical ventilation. To evaluate the effect of large tidal volume ventilation on oxygenation and ventilation, the baseline 13 mL/kg tidal volume (VT) (calculated by the ideal body weight) was increased in 3 mL/kg volume increments to 22 mL/kg, while ventilatory rate (RR) and inspiratory time (TI) were kept constant. Each volume increment was maintained for 15 min. Gas exchange was assessed by measuring the arterial blood oxygen tensions, and calculating the indices of alveolar-arterial oxygen tension difference [P(A-a)O2] and arterial/alveolar oxygen tension ratio (a/A). Peak inspiratory airway pressure (Ppeak), end-inspiratory airway pressure (Pplateau), and compliance of the respiratory system (CRS) were recorded using the Capnomac Ultima (Datex, Helsinki, Finland) on-line respiratory monitor. Increasing tidal volumes to 22 mL/kg increased the recorded Ppeak (26.3 +/- 4.1 vs 37.9 +/- 3.2 cm H2O, P < 0.008), Pplateau (21.5 +/- 3.6 vs 27.7 +/- 4.3 cm H2O, P < 0.01), and CRS (39.8 +/- 7.7 vs 48.5 +/- 8.3 mL/cm H2O) significantly without improving arterial oxygen tension and resulted in severe hypocapnia. Since changes in arterial oxygenation were small and not statistically significant, mechanical ventilation of morbidly obese patients with large VTS seems to offer no advantage to smaller (13 mL/kg ideal body weight) VTS.

Adult↗
PubMed1994

Comparison of neostigmine-induced recovery with spontaneous recovery from mivacurium-induced neuromuscular block.

In 24 ASA I-II adults anaesthetized with thiopentone, fentanyl and nitrous oxide in oxygen, we studied neuromuscular transmission with isometric adductor pollicis monitoring. Patients received mivacurium 0.2 mg kg-1 followed by an infusion lasting at least 60 min and adjusted to maintain twitch height at 1-5%. After termination of the mivacurium infusion, when twitch height spontaneously regained 25% of its control value, the patients were allocated to two groups of 12 patients each. In group NEO patients received neostigmine 40 micrograms kg-1 and atropine 15 micrograms kg-1 and in group SPO neuromuscular transmission was allowed to recover spontaneously. Twitch height was measured every 10 s and train-of-four (TOF) (2 Hz) every 3 min. After 15 min, residual force after tetanic stimulation (50 and 100 Hz, 5-s duration (RF50HZ, RF100HZ), 1 min apart) were recorded sequentially. At 15 min, mean TOF ratio was greater in group NEO (0.94 (SEM 0.01)) than in group SPO (0.87 (0.02)) (P < 0.01). All patients in group NEO recovered to a TOF ratio greater than 0.7 after 6 min compared with 15 min in group SPO (P < 0.005). A TOF ratio greater than 0.9 was observed in all patients in group NEO compared with only six in group SPO (P < 0.025). Nevertheless, RF50HZ and RF100HZ did not differ significantly (0.92 (0.01) (group NEO), 0.91 (0.01) (group SPO) and 0.83 (0.02) (group NEO), 0.78 (0.03) (group SPO), respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The influence of atropine dose on recovery from vecuronium-induced neuromuscular blockade.

To determine whether the dose of atropine affects the rate of neostigmine-induced recovery from vecuronium-induced neuromuscular blockade, the authors monitored isometric adductor pollicis mechanical activity in 36 anesthetized (thiopental, fentanyl, nitrous oxide) adult patients (ASA physical status 1 or 2). Once surgery was completed and twitch height had spontaneously regained 25% of its initial value, the patients were randomly allocated into three groups (A10, A15, A20; n = 12 in each group) according to the dose of atropine (10, 15, or 20 micrograms/kg) that was mixed with 40 micrograms/kg neostigmine. Twitch height, train-of-four, and 50- and 100-Hz tetanic fade were recorded for 15 min after the administration of the reversal agents. No significant differences were found among the three groups in the final twitch height (95% +/- 2%), train-of-four (87% +/- 1%, 88% +/- 2%, 89% +/- 1%), and 50-Hz tetanic fade (90% +/- 1%, 94% +/- 1%, 93% +/- 1%) (mean +/- SEM). Fifteen minutes after reversal, fade in response to 100-Hz tetanus was statistically greater in the A10 group than in the two other groups (70% +/- 3% of control versus 84% +/- 4% and 81% +/- 2%) (mean +/- SEM, P less than 0.05). The present results demonstrate that larger doses of atropine facilitate neostigmine's reversal of vecuronium neuromuscular blockade. The clinical implications of the differences observed in this study remain to be determined.

Adult↗
PubMed1991

Effects of residual concentrations of isoflurane on the reversal of vecuronium-induced neuromuscular blockade.

Thirty-six anesthetized patients (ASA physical status 1 or 2) undergoing elective surgery were monitored (isometric adductor pollicis mechanical activity) to detect the effects of discontinuing isoflurane anesthesia upon the reversal of vecuronium-induced neuromuscular blockade. Neuromuscular blockade was produced by vecuronium 100 micrograms/kg and additional doses of 20 micrograms/kg until completion of surgery. The patients were randomly divided into three groups: in the control group (n = 12), only fentanyl/N2O was given; in the "isostable" group (n = 12), isoflurane at an end-tidal concentration of 1.25% was maintained throughout anesthesia; in the "isostop" group (n = 12), isoflurane 1.25% was discontinued before neostigmine administration. In all groups, paralysis was antagonized with 15 micrograms/kg intravenous (iv) atropine and 40 micrograms/kg iv neostigmine when the twitch height (0.1 Hz) had regained 25% of its control value. The measured parameters were twitch height, train-of-four, and 50--100-Hz tetanic fade. No significant differences were found among the three groups with respect to the final twitch heights and tetanic fades at 50 Hz. In the isostable group, final mean train-of-four was significantly less (75%) than in the other patients (88%) (P less than 0.01). Mean tetanic fade at 100 Hz was significantly less in the isostable group (31%) than in the isostop group (57%) (P less than 0.01) and control group (84%) (P less than 0.01). We conclude that discontinuing isoflurane anesthesia for 15 min improves the reversal of a vecuronium paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗