During robot assisted laparoscopic radical prostatectomy (RALRP), a CO2 pneumoperitoneum (CO2PP) is applied and the patient is placed in a head-down position. Intracranial pressure (ICP) is expected ...to acutely increase under these conditions. A non-invasive method, the optic nerve sheath diameter (ONSD) measurement, may warn us that the mechanism of protective cerebrospinal fluid (CSF) shifts becomes exhausted.
After obtaining IRB approval and written informed consent, ONSD was measured by ocular ultrasound in 20 ASA I-II patients at various stages of the RALRP procedure: baseline awake, after induction, after applying the CO2PP, during head-down position, after resuming the supine position, in the postoperative anaesthesia care unit, and on day one postoperatively. Cerebral perfusion pressure (CPP) was calculated as the mean arterial (MAP) minus central venous pressure (CVP).
The ONSD did not change during head-down position, although the CVP increased from 4.2(2.5) mm Hg to 27.6(3.8) mm Hg. The CPP was decreased 70 min after assuming the head-down position until 15 min after resuming the supine position, but remained above 60 mm Hg at all times.
Even though ICP has been documented to increase during CO2PP and head-down positioning, we did not find any changes in ONSD during head-down position. These results indicate that intracranial blood volume does not increase up to a point that CSF migration as a compensation mechanism becomes exhausted, suggesting any increases in ICP are likely to be small.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Drug interactions may reveal mechanisms of drug action: additive interactions suggest a common site of action, and synergistic interactions suggest different sites of action. We applied this ...reasoning in a review of published data on anesthetic drug interactions for the end-points of hypnosis and immobility.
We searched Medline for all manuscripts listing propofol, etomidate, methohexital, thiopental, midazolam, diazepam, ketamine, dexmedetomidine, clonidine, morphine, fentanyl, sufentanil, alfentanil, remifentanil, droperidol, metoclopramide, lidocaine, halothane, enflurane, isoflurane, sevoflurane, desflurane, N2O, and Xe that contained terms suggesting interaction: interaction, additive, additivity, synergy, synergism, synergistic, antagonism, antagonistic, isobologram, or isobolographic. When available, data were reanalyzed using fraction analysis or response surface analysis.
Between drug classes, most interactions were synergistic. The major exception was ketamine, which typically interacted in either an additive or infra-additive (antagonistic) manner. Inhaled anesthetics typically showed synergy with IV anesthetics, but were additive or, in the case of nitrous oxide and isoflurane, possibly infra-additive, with each other.
Except for ketamine, IV anesthetics acting at different sites usually demonstrated synergy. Inhaled anesthetics usually demonstrated synergy with IV anesthetics, but no pair of inhaled anesthetics interacted synergistically.
Carbon dioxide absorbers allow the use of fresh gas flow below minute ventilation (V˙E). Models are developed and tested in vitro to quantify their performance with variable carbon dioxide load ...(V˙CO2), fresh gas flow, V˙E, end-tidal carbon dioxide (ETco2) fraction, and the type of workstation used.
First principles are used to derive a linear relationship between fresh gas flow and fractional canister usage or FCU0.5 (the reciprocal of the time for the inspiratory carbon dioxide fraction to reach 0.5%). This forms the basis for two basic models in which V˙E was measured by spirometry or calculated. These models were extended by multiplying V˙E with an empirical workstation factor. To validate the four models, two hypotheses were tested. To test whether the FCU0.5 intercept varied proportionally with V˙CO2 and was independent of V˙E, FCU was measured for 10 canisters tested with a fixed 0.3 l/min fresh gas flow and a range of V˙CO2 while V˙E was either constant or adjusted to maintain ETco2 fraction. A t test was used to compare the two groups. To confirm whether a change in V˙CO2 accompanied by a change in V˙E to maintain ETco2 fraction would shift the linear fresh gas flow-FCU0.5 relationship in a parallel manner, 19 canisters were tested with different combinations of V˙CO2 and fresh gas flow. These measured FCU values were compared to those predicted by the four models using Varvel's performance criteria.
With 0.3 l/min fresh gas flow, FCU0.5 was proportional with V˙CO2 and independent of whether V˙E was adjusted to maintain ETco2 fraction or not (P = 0.962). The hypothesized parallel shift of the fresh gas flow-FCU0.5 relationship was confirmed. Both extended models are good candidate models.
The models predict prepacked canister performance in vitro over the range of V˙E, fresh gas flow, and V˙CO2 likely to be encountered in routine clinical practice. In vivo validation is still needed.
Based primarily on the high cost, low potency and profound greenhouse gas effect of desflurane, the authors advocated for switching from desflurane to sevoflurane to minimise the cost and ...environmental impact of inhalation anaesthesia. The primary reason identified in the study for not using FGF <1 L/min with sevoflurane was the recommendation against low flow rates on the drug data sheets or package inserts because of concern for compound A production.2 It appears that low flow practices per se are not seen as a risk because most desflurane users did use low flows, and 59% of those sampled were using machines that automate low-flow vapour delivery. According to the Australian Therapeutic Goods Administration, “The concentrations of Compound A, measured in the anaesthesia circuit when sevoflurane is used clinically are not known to be deleterious to humans …. a level of Compound A exposure at which clinical nephrotoxicity might be expected to occur has not been established, it is prudent to consider all of the factors leading to Compound A exposure in humans, … Because of limited clinical experience with sevoflurane in low – flow systems, fresh gas flow rates below 2 L/min in a circle absorber system are not recommended”.2 The provenance of information in data sheets is worth considering. Sevoflurane costs decrease more rapidly than absorbent costs increase and total cost and environmental impact will still be minimised as flows approach a closed circuit condition.11 Volatile anaesthetic agents are unique in that it is possible to significantly reduce the mass of drug delivered to the circuit (by lowering FGFs) without altering the amount that actually enters the patient.
Age-adjusted fraction of minimum alveolar concentration derived from end-tidal anesthetic partial pressure measurement remains a useful drug advisory display to help prevent awareness if interpreted ...with proper understanding of the quantal and probabilistic nature of minimum alveolar concentration, semantics, drug interactions, and hysteresis.
Isocapnic hyperventilation (ICHV) is occasionally used to maintain the end-expired CO
2
partial pressure (P
ET
CO
2
) when the inspired CO
2
(P
I
CO
2
) rises. Whether maintaining P
ET
CO
2
with ICHV ...during an increase of the P
I
CO
2
also maintains arterial PCO
2
(P
a
CO
2
) remains poorly documented. 12 ASA PS I–II subjects undergoing a robot-assisted radical prostatectomy (RARP) (n = 11) or cystectomy (n = 1) under general endotracheal anesthesia with sevoflurane in O
2
/air (40% inspired O
2
) were enrolled. P
I
CO
2
was sequentially increased from 0 to 0.5, 1.0, 1.5 and 2% by adding CO
2
to the inspiratory limb of the circle system, while increasing ventilation to a target P
ET
CO
2
of 4.7–4.9% by adjusting respiratory rate during controlled mechanical ventilation. P
a-ET
CO
2
gradients were determined after a 15 min equilibration period at each P
I
CO
2
level and compared using ANOVA. Mean (standard deviation) age, height, and weight were 66 (6) years, 171 (6) cm, and 75 (8) kg, respectively. Capnograms were normal and hemodynamic parameters remained stable. P
ET
CO
2
could be maintained within 4.7–4.9% in all subjects at all times except in 1 subject with 1.5% P
I
CO
2
and 5 subjects with 2.0% P
I
CO
2
; data from the one subject in whom both 1.5 and 2.0% P
I
CO
2
resulted in P
ET
CO
2
> 5.1% were excluded from analysis. P
a-ET
CO
2
gradients did not change when P
I
CO
2
increased. The effect of a modest rise of P
I
CO
2
up to 1.5% on P
ET
CO
2
during RARP can be readily overcome by increasing ventilation without altering the P
a-ET
CO
2
gradients. At higher P
I
CO
2
, airway pressures may become a limiting factor, which requires further study.
Patient safety is an activity to mitigate preventable patient harm that may occur during the delivery of medical care. The European Board of Anaesthesiology (EBA)/European Union of Medical ...Specialists had previously published safety recommendations on minimal monitoring and postanaesthesia care, but with the growing public and professional interest it was decided to produce a much more encompassing document. The EBA and the European Society of Anaesthesiology (ESA) published a consensus on what needs to be done/achieved for improvement of peri-operative patient safety. During the Euroanaesthesia meeting in Helsinki/Finland in 2010, this vision was presented to anaesthesiologists, patients, industry and others involved in health care as the ‘Helsinki Declaration on Patient Safety in Anaesthesiology’. In May/June 2020, ESA and EBA are celebrating the 10th anniversary of the Helsinki Declaration on Patient Safety in Anaesthesiology; a good opportunity to look back and forward evaluating what was achieved in the recent 10 years, and what needs to be done in the upcoming years. The Patient Safety and Quality Committee (PSQC) of ESA invited experts in their fields to contribute, and these experts addressed their topic in different ways; there are classical, narrative reviews, more systematic reviews, political statements, personal opinions and also original data presentation. With this publication we hope to further stimulate implementation of the Helsinki Declaration on Patient Safety in Anaesthesiology, as well as initiating relevant research in the future.
Oxygen is one of the most commonly used drugs by anesthesiologists. The World Health Organization (WHO) gave recommendations regarding perioperative oxygen administration, but the practice of oxygen ...use in anesthesia, critical emergency, and intensive care medicine remains unclear.
We conducted an online survey among members of the European Society of Anaesthesiology and Intensive Care (ESAIC). The questionnaire consisted of 46 queries appraising the perioperative period, emergency medicine and in the intensive care, knowledge about current recommendations by the WHO, oxygen toxicity, and devices for supplemental oxygen therapy.
Seven hundred ninety-eight ESAIC members (2.1% of all ESAIC members) completed the survey. Most respondents were board-certified and worked in hospitals with > 500 beds. The majority affirmed that they do not use specific protocols for oxygen administration. WHO recommendations are unknown to 42% of respondents, known but not followed by 14%, and known and followed by 24% of them. Respondents prefer inspiratory oxygen fraction (FiO
) ≥80% during induction and emergence from anesthesia, but intraoperatively < 60% for maintenance, and higher FiO
in patients with diseased than non-diseased lungs. Postoperative oxygen therapy is prescribed more commonly according to peripheral oxygen saturation (SpO
), but shortage of devices still limits monitoring. When monitoring is used, SpO
≤ 95% is often targeted. In critical emergency medicine, oxygen is used frequently in patients aged ≥80 years, or presenting with respiratory distress, chronic obstructive pulmonary disease, myocardial infarction, and stroke. In the intensive care unit, oxygen is mostly targeted at 96%, especially in patients with pulmonary diseases.
The current practice of perioperative oxygen therapy among respondents does not follow WHO recommendations or current evidence, and access to postoperative monitoring devices impairs the individualization of oxygen therapy. Further research and additional teaching about use of oxygen are necessary.
Anesthetic agent consumption is often calculated as the product of fresh gas flow (FGF) and vaporizer dial setting (F
VAP
). Because F
VAP
of conventional vaporizers is not registered in automated ...anesthesia records, retrospective agent consumption studies are hampered. The current study examines how F
VAP
can be retrospectively calculated from the agent’s inspired (F
IN
) and end-expired concentration (F
ET
), FGF, and minute ventilation (MV). Theoretical analysis of agent mass balances in the circle breathing reveals F
VAP
= F
IN
− (dead space fraction * F
IN
+ (1 − dead space fraction) * F
ET
) * (1 − FGF/MV)/(1-(1 − FGF/MV)). F
IN
, F
ET
, FGF and MV are routinely monitored, but dead space fraction is unknown. Dead space fraction for sevoflurane, desflurane, and isoflurane was therefore determined empirically from an unpublished data set of 161 patient containing F
VAP
, F
IN
, F
ET
, MV and FGF ranging from 0.25 to 8 L/min delivered via an ADU® (GE, Madison, WI, USA). Dead space fraction for each agent was determined empirically by having Excel’s solver function calculate the value of dead space fraction that minimized the sum of the squared differences between dialed F
VAP
and predicted F
VAP
. With dead space fraction known, the model was then prospectively tested for sevoflurane in O
2
/air using data collected over the course of two weeks with one FLOW-i (Getinge, Solna, Sweden) and one Zeus workstation (Dräger, Lübeck, Germany). Because both workstations use an electronically controlled vaporizer/injector, the dialed F
VAP
were available to allow the calculation of median performance error (MDPE) and median absolute performance error (MDAPE). MDPE and MDAP are reported as median and interquartiles. The empirical dead space fraction for isoflurane, sevoflurane, and desflurane were 0.59, 0.49, and 0.66, respectively. For prospective testing, a total of 149.4 h of useful data were collected from 78 patient with the Zeus and Flow-i combined, with FGF ranging from 0.18 to 8 L/min. The model predicted dialed F
VAP
well, with a MDPE of −1 (−11, 6) % and MDAPE of 8 (4, 17) %. F
VAP
can be retrospectively calculated from F
IN
, F
ET
, FGF, and MV plus an agent specific dead space fraction factor with a degree of error that we believe suffices for retrospective sevoflurane consumption analyses. Performance with other agents and N
2
O awaits further validation.
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