Comparison of Equiosmolar Doses of 7.5% Hypertonic Saline and 20% Mannitol on Cerebral Oxygenation Status and Release of Brain Injury Markers During Supratentorial Craniotomy: A Randomized Controlled Trial.

BACKGROUND: Hyperosmolar therapy is the mainstay of treatment to reduce brain bulk and optimize surgical exposure during craniotomy. This study investigated the effect of equiosmolar doses of 7.5% hypertonic saline (HTS) and 20% mannitol on intraoperative cerebral oxygenation and metabolic status, systemic hemodynamics, brain relaxation, markers of cerebral injury, and perioperative craniotomy outcomes. METHODS: A total of 51 patients undergoing elective supratentorial craniotomy were randomly assigned to receive 7.5% HTS (2 mL/kg) or 20% mannitol (4.6 mL/kg) at scalp incision. Intraoperative arterial and jugular bulb blood samples were collected at predefined time intervals for assessment of various indices of cerebral oxygenation; multiple hemodynamic variables were concomitantly recorded. S100B protein and neuron-specific enolase levels were determined at baseline, and at 6 and 12 hours after surgery for assessment of neuronal injury. Brain relaxation and perioperative outcomes were also assessed. RESULTS: Demographic and intraoperative data, brain relaxation score, and perioperative outcomes were comparable between groups. Jugular bulb oxygen saturation and partial pressure of oxygen, arterial-jugular oxygen and carbon dioxide differences, and brain oxygen extraction ratio were favorably affected by 7.5% HTS up to 240 minutes postinfusion ( P <0.05), whereas mannitol was associated with only a short-lived (up to 15 min) improvement of these indices ( P <0.05). The changes in cerebral oxygenation corresponded to transient expansion of intravascular volume and improvements of cardiovascular performance. Increases in S100B and neuron-specific enolase levels at 6 and 12 hours after surgery ( P <0.0001) were comparable between groups. CONCLUSIONS: The conclusion is that 7.5% HTS has a more beneficial effect on cerebral oxygenation than an equiosmolar dose of 20% mannitol during supratentorial craniotomy, yet no clear-cut clinical superiority of either solution could be demonstrated.

Control of Hemodynamic Responses and Perioperative Outcomes in Transsphenoidal Pituitary Surgery: A Qualitative Systematic Review of the Available Evidence.

Transnasal transsphenoidal (TNTS) pituitary surgery is associated with short-lived but intense nociceptive stimuli which cause substantial hemodynamic perturbations that may increase blood loss and impair visualization of the surgical field. This systematic review aimed to critically appraise the clinical evidence for the efficacy and safety of various anesthetic techniques, other pharmacological modalities, and supplementary interventions by assessing intraoperative systemic hemodynamics, use of adjunct medications, quality of the surgical field, intraoperative blood loss, and recovery profiles in patients undergoing TNTS pituitary surgery. Relevant randomized clinical trials and observational studies were identified in a systematic literature search; 16 studies (13 randomized clinical trials, 3 observational studies) enrolling a total of 907 patients were identified for inclusion in this review. Propofol provided more potent hemodynamic control compared with volatile anesthetics with a sparing effect on the need for additional drugs to blunt hemodynamic responses. Recovery profiles between propofol and sevoflurane were either equivalent or favored sevoflurane, but both agents were superior to isoflurane. Regarding intraoperative analgesia, remifentanil was associated with superior hemodynamic control and recovery profiles than fentanyl. Dexmedetomidine had beneficial effects on hemodynamics, surgical field quality, recovery characteristics, and nociceptive properties compared with placebo. Although there was no clear-cut superiority of other adjunct pharmacological modalities on hemodynamic responses during surgery, regional blocks were associated with beneficial impacts on both primary and secondary outcomes. In summary, short-acting anesthetics, analgesics and dexmedetomidine seem to improve intraoperative hemodynamics, blood loss, and recovery qualities during TNTS pituitary surgery. However, definitive conclusions cannot be drawn because of methodological heterogeneity in the identified studies.

Analgesic Efficacy and Safety of Local Infiltration of Tramadol in Pediatric Tonsillectomy Pain: A Systematic Review and Meta-Analysis.

OBJECTIVES: The aim of this systematic review and meta-analysis was to appraise clinical evidence of the impact of peritonsillar infiltration of tramadol, on postoperative pain control and the occurrence of adverse effects in children undergoing tonsillectomy. METHODS: A database search was conducted to identify randomized controlled trials (RCTs) pertinent to peritonsillar infiltration of tramadol compared to no treatment (placebo) or other analgesic regimens. The outcomes of interest were postoperative pain intensity, time to first analgesic demand, rescue analgesic consumption up to 24 hours after intervention, and the occurrence of adverse events. RESULTS: Twelve RCTs enrolling 972 pediatric patients were selected for qualitative analysis, among which eight were suitable for meta-analysis. Tramadol infiltration induced a significant reduction of pain intensity up to 24 hours post-tonsillectomy (mean difference [MD], -2.31; 95% confidence interval [CI], -3.49 to -1.12; P < 0.001; I2  = 97%) and time to first analgesic (MD 180.54; 95% CI, 56.91 to 304.18; P = 0.004; I2  = 99%), with no profound impact on postoperative nausea and vomiting (risk ratio [RR] 0.98; 95% CI, 0.73 to 1.32; P = 0.90; I2  = 0%) compared to the placebo group. The analgesic efficacy of tramadol infiltration was equivalent to the local or systematic use of ketamine or infiltration with local anesthetics. This effect was further enhanced when tramadol infiltration served as an adjunct to other analgesic interventions. No serious adverse events were reported. CONCLUSIONS: In children undergoing tonsillectomy, peritonsillar infiltration of tramadol is associated with a postoperative analgesic benefit when compared to placebo, with negligible adverse events. Yet, no definite conclusion can be drawn due to the low quality, considerable heterogeneity, and paucity of the available data.

Early and late clinical outcomes after decompressive craniectomy for traumatic refractory intracranial hypertension: a systematic review and meta-analysis of current evidence.

INTRODUCTION: Decompressive craniectomy (DC) to control refractory intracranial hypertension in patients with traumatic brain injury (TBI), has been listed as possible but controversial therapeutic approach in the latest version of TBI management guidelines. This study aimed to perform a systematic review and meta-analysis on efficacy and safety of DC compared to standard care in TBI patients. EVIDENCE ACQUISITION: A database search from 2011 to 2017 was conducted to identify studies pertinent to DC compared to standard care after TBI. The primary outcomes were mortality and functional outcome upon hospital discharge and at 6 and 12 months after intervention, whereas secondary outcomes were intracranial pressure (ICP) control, hospitalization data and occurrence of adverse events. EVIDENCE SYNTHESIS: Three randomized controlled trials and two observational studies enrolling 3451 patients were selected for qualitative analysis, among which four were included in the meta-analysis. DC-treated patients showed a significant reduction of overall mortality (RR, 0.57; 95% CI: 0.5-0.66; P<0.001; I2=17%) with no profound beneficial effect on functional outcome (RR, 0.89; 95% CI: 0.78-1.02; P=0.09; I2=58%) compared to those receiving standard care. A more efficient ICP reduction and a tendency towards shorter duration of hospitalization were recorded in DC versus standard care group. Adverse events are more common in DC-treated patients. CONCLUSIONS: It seems that, in TBI patients with intracranial hypertension, the use of DC is associated with survival benefit when compared to medical therapy alone, but with no clear improvement of functional outcome. Yet no definite conclusion can be drawn due to limited quantity and considerable heterogeneity of available data.

Dexmedetomidine as a sedative and analgesic adjuvant in spine surgery: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: This systematic review and meta-analysis appraise the clinical evidence on efficacy and safety of dexmedetomidine (DEX), as a sedative and analgesic adjunct in adult patients undergoing spine surgery. METHODS: A database search was conducted to identify randomized clinical trials (RCTs) pertinent to the perioperative use of DEX in spine surgery. Sedative and analgesic efficacy of DEX constituted the primary outcomes, whilst the incidence of hemodynamic changes, quality of recovery and occurrence of adverse events served as secondary ones. RESULTS: Fifteen studies enrolling a total of 913 patients were selected for qualitative analysis, among which eight RCTs incorporating a placebo comparison group were included in the meta-analysis. Most of the retrieved studies were of moderate to good quality and demonstrated an acceptable risk of bias. DEX-treated patients showed a significant reduction of both propofol [mean difference (MD), -214.47 mg; 95%CI, -253.16 to -175.78; P < 0.001] and morphine equivalents consumption both intraoperatively and postoperatively (MD, -2.69; 95% CI, -3.05 to -2.33; P < 0.001 and MD, -4.36 mg; 95%CI, -6.93 to -1.79; P < 0.001, respectively) compared to those assigned to placebo. Postoperative nausea and vomiting incidence were comparable between DEX and placebo groups, whilst other adverse events were not consistently reported. CONCLUSIONS: DEX emerges as an attractive alternative to standard sedative and analgesic modalities applied in spine surgery, by attaining a notable sedative and opioid-sparing effect, which goes with an enhanced safety profile. Yet, no definite conclusion can be drawn due to the considerable heterogeneity of available data. TRIAL REGISTRATION: PROSPERO CRD42015029537.

Benchmarking the Applicability of Four Methods of Endotracheal Tube Cuff Inflation for Optimal Sealing: A Randomized Trial.

PURPOSE: To assess the comparable applicability of four methods of endotracheal tube cuff (ETTc) inflation on the basis of optimal level of intracuff pressure and presence of intubation-related complications. DESIGN: Double-blind, randomized trial. METHODS: A total of 139 adult surgical patients scheduled to undergo nitrous oxide-free general anesthesia were assigned into one of four groups according to the method used for ETTc inflation. The cuff pressure and air volume applied in each method, and laryngotracheal complications were recorded. FINDINGS: The highest and lowest ETTc pressure and air volume values were recorded in palpation and minimum leak technique group, respectively. Laryngotracheal complaints were maximized in palpation and minimized in minimal occlusive volume and minimum leak techniques. CONCLUSIONS: The air-return back into the syringe method emerges as an attractive and simple-to-perform alternative regarding effective ETTc sealing and low incidence of intubation-related morbidity when a cuff manometer is not readily available. STUDY REGISTRATION: ACTRN12615000699561.

Prophylaxis of postoperative complications after craniotomy.

PURPOSE OF REVIEW: This review reports an update of the evidence on practices applied for the prevention and management of the most common complications after craniotomy surgery. RECENT FINDINGS: Latest guidelines support the combined thromboprophylaxis with the use of both mechanical and chemical modalities, preferably applied within 24 h after craniotomy. Nevertheless, a heightened risk of minor hemorrhagic events remains an issue of concern. Postoperative nausea and vomiting (PONV) and pain constitute the complications most commonly encountered during the first 24 h postcraniotomy. Recently, neurokinin type-1 receptor antagonists have been tested as adjuncts for PONV prophylaxis with encouraging results, whereas dexmedetomidine and gabapentinoids emerge as promising alternatives for postcraniotomy pain management. The available data for seizure prophylaxis following craniotomy lacks scientific quality; thus, this remains still a debatable issue. Significantly, a growing body of evidence supports the superiority of levetiracetam over the older antiepileptic drugs (AEDs), in terms of efficacy and safety. SUMMARY: Optimum management of postoperative complications is incorporated as an integral part of the augmented quality of care in patients undergoing craniotomy surgery, aiming to improve outcomes. This review may serve as a benchmark for neuroanesthetists for heightened clinical awareness and prompt institution of well-documented practices.

Postoperative Pain Control Following Craniotomy: A Systematic Review of Recent Clinical Literature.

BACKGROUND: Pain intensity after craniotomy is considered to be moderate to severe during the first 2 postoperative days. The ideal pain treatment to facilitate a rapid postoperative recovery and optimize outcome is unknown. OBJECTIVES: This systematic review aims to report current clinical evidence related to pharmacological and adjuvant analgesic modalities for postcraniotomy pain control. DESIGN: Systematic review of randomized controlled trials (RCTs). DATA SOURCES: PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (January 2011 to April 2016). ELIGIBILITY CRITERIA: Original research involving the use of any analgesic drug, analgesic method, or nonpharmacological intervention for postcraniotomy pain relief, as assessed by pain scores up to 48 hours postoperatively, supplemental analgesic requirements, or occurence of adverse events. RESULTS: Nineteen RCTs enrolling a total of 1,805 patients were included. Most of the retrieved studies were of moderate-to-good methodological quality. Systemic pharmacological intervention was assessed in 14 RCTs. Opioids (5 RCTs) provided superior pain relief to other analgesics with no significant side effects, but the quality of studies was low. Diclofenac (3 RCTs) presented adequate craniotomy pain control without any adverse effects, while the use of parecoxib is not supported. Dexmedetomidine (3 RCTs) provided adequate transitional analgesia, but further research is needed. Data on the analgesic efficacy of gabapentin, pregabalin, and intravenous lidocaine are very limited (1 RCT for each). Scalp infiltration/block (3 RCTs) provided adequate analgesia in the early postoperative period, while more studies are needed to verify the analgesic benefit obtained from nonpharmacological interventions, such as multipoint electro-acupuncture, in craniotomy surgery (2 RCTs). CONCLUSIONS: No definite recommendations can be made based on this systematic review of pharamacological interventions following craniotomy due to significant divergence in the methodology of available studies. Limited evidence on scalp infiltration/block suggests an adequate analgesic effect in the early postoperative period. Analgesic efficacy of dexmedetomidine and multipoint electro-acupuncture needs further evaluation.

Role of Dexmedetomidine for Sedation in Neurocritical Care Patients: A Qualitative Systematic Review and Meta-analysis of Current Evidence.

INTRODUCTION: This systematic review appraises the clinical evidence on efficacy and safety of dexmedetomidine (DEX), as a sole sedative or as sedative adjunct in adult neurocritical care (NCC) patients. MATERIALS AND METHODS: A database search was conducted to identify randomized clinical trials and observational studies reporting the use of DEX alone or as adjunct for sedation in NCC setting. The primary outcome was the occurrence of hemodynamic changes, whereas the secondary outcomes were sedative and analgesic efficacy, quality and time to awakening, and development of adverse events. RESULTS: Eight trials including 3 randomized controlled trials and 5 observational studies, enrolling 650 patients, were selected. All the retrieved studies had a high risk of bias and a low to moderate quality. Dexmedetomidine provided a better sedation score and reduced analgesic requirements when compared to propofol or midazolam sedation. No statistically significant difference in the combined hemodynamic effect (hypotension or bradycardia) between DEX and controls (risk ratio, 1.50; 95% confidence interval, 0.65-3.48; P = 0.34; I = 56%) was identified. Adverse events were not consistently reported. CONCLUSIONS: Available clinical literature supporting the efficacy and safety of DEX use in adult NCC setting is of limited quantity and quality. However, from the current evidence on the use of DEX in NCC, as sole sedative agent or as an adjunct, seems to be both efficient and safe.

Impact of anesthetic technique on the stress response elicited by laparoscopic cholecystectomy: a randomized trial.

The aim of this randomized, double-blind clinical trial was to elucidate the impact of general anesthesia alone (GA) or supplemented with epidural anesthesia (EpiGA) on surgical stress response during laparoscopic cholecystectomy, using stress hormones, glucose, and C-reactive protein (CRP), as potential markers. Sixty-two patients scheduled to undergo elective laparoscopic cholecystectomy were randomly assigned into two groups to receive either GA or EpiGA. Stress hormones [cortisol (COR), human growth hormone (hGH), prolactine (PRL)], glucose, and CRP were determined 1 day before surgery, intraoperatively, and upon first postoperative day (POD1). Plasma COR, hGH, PRL, and glucose levels were maximized intraoperatively in GA and EpiGA groups and reverted almost to baseline on POD1. Significant between-group differences were detected for COR and glucose either intraoperatively or postoperatively, but this was not the case for hGH. PRL was elevated in GA group only intraoperatively. Although, CRP was minimally affected intraoperatively, a notable augmentation on POD1, comparable in both groups, was recorded. These results indicate that hormonal and metabolic stress response is slightly modulated by the use of epidural block supplemented by general anesthesia, in patients undergoing laparoscopic cholecystectomy cholecystectomy. Nevertheless, inflammatory reaction as assessed by CRP seems to be unaffected by the anesthesia regimen.

Interaction of a Cannabinoid-2 Agonist With Tramadol on Nociceptive Thresholds and Immune Responses in a Rat Model of Incisional Pain.

The aim of this study was to elucidate the antinociceptive interaction between cannabinoids and tramadol and their impact on proinflammatory response, in terms of serum intereleukin-6 (IL-6) and interleukin-2 (IL-2) release, in a rat model of incisional pain. Prospective randomized trial assessing the individual or combined application of intraperitoneal tramadol (10 mg/kg) and the selective cannabinoid-2 (CB-2) agonist (R,S)-AM1241 (1 mg/kg) applied postsurgical stress stimulus. Pharmacological specificity was established by antagonizing tramadol with naloxone (0.3 mg/kg) and (R,S)-AM1241 with SR144528 (1 mg/kg). Thermal allodynia was assessed by hot plate test 30 (T30), 60 (T60), and 120 (T120) minutes after incision. Blood samples for plasma IL-6 and IL-2 level determination were obtained 2 hours after incision. Data from 42 rats were included in the final analyses. Significant augmentation of thermal threshold was observed at all time points, after administration of either tramadol or (R,S)-AM1241 compared with the control group (P = 0.004 and P = 0.015, respectively). The combination of (R,S)-AM1241 plus tramadol promoted the induced antinociception in an important manner compared with control (P = 0.002) and (R,S)-AM1241 (P = 0.022) groups. Although the antiallodynic effect produced by tramadol was partially reversed by naloxone 30 and 60 minutes after incision (P = 0.028 and P = 0.016, respectively), SR144528 blocked the effects of (R,S)-AM1241 administration in a significant manner (P = 0.001) at all time points. Similarly, naloxone plus SR144528 also blocked the effects of the combination of (R,S)-AM1241 with tramadol at all time points (P = 0.000). IL-6 level in (R,S)-AM1241 plus tramadol group was significantly attenuated compared with control group (P = 0.000). Nevertheless, IL-2 levels remained unchanged in all experimental groups. It seems that the concomitant administration of a selective CB-2 agonist with tramadol in incisional pain model may improve antinociceptive effects and immune responses of cannabinoids, but this effect does not seem to be superior to that of tramadol alone.

Looking into the profile of those who succeed in losing weight with an intragastric balloon.

BACKGROUND: Weight loss by means of an intragastric balloon is an advantageous procedure, as usage of such a balloon is minimally invasive and of minimal operational risk. Nevertheless, despite the encouraging results referred in to large population studies, its success rate as a treatment option is still questionable. The aim of this study was to classify and analyze all parameters recorded in a database of a treatment protocol concerning obese individuals handled by an intragastric balloon, in an attempt to delineate the comparable profile of those who succeeded to lose weight and those who failed. SUBJECTS AND METHODS: Retrospective data collection, including demographic and anthropometric data, social and psychological factors, educational status, and attendance at sessions and the exercise program, was conducted. Using as a criterion for grouping the percentage of excess weight loss (%EWL), the successful (%EWL ≥50%) and the poor (%EWL ≤20%) responders were identified. RESULTS: In total, 583 patients were assessed. Initial and ideal body weight (BW), initial body mass index (BMI), and excess weight were significantly lower in the %EWL ≥50% group (P<.001). Upon balloon removal, both groups exhibited a significant difference regarding BW, BW lost, BMI, and %EWL (P<.001). Advanced age (odds ratio [OR]=1.06; P<.001), female gender (OR=3.31; P<.001), basic educational level (OR=3.12; P<.001), and single or divorced marital status (OR=6.00; P<.001) were identified as the most powerful determinants of %EWL ≥50%. Moreover, attendance at more than four monthly interviews and strict exercise program commitment contributed significantly to a favorable outcome. CONCLUSIONS: Our findings could serve as an initial step for further research into factors possibly contributing to the early identification of those individuals who will notably benefit from usage of an intragastric balloon regarding BW loss.

Influence of apneic oxygenation on cardiorespiratory system homeostasis.

PURPOSE: The aim of this study was to elucidate the magnitude of variations in oxygenation indices and the pattern of hemodynamic changes in response to the net effect of tracheal apneic oxygenation (AO) with a view to define the safe time limit of its application. METHODS: After obtaining Animal Research Ethics Committee approval, AO was applied in 12 piglets for 40 min. Arterial (a) and mixed venous (v) blood samples for oxygen (O2) and carbon dioxide (CO2) tension (PaO2/PvO2, PaCO2/PvCO2), O2 saturation (SaO2/SvO2), pHa, base excess (BEa), and bicarbonate (HCO3a) determination and for alveolar O2 tension (PAO2), PaO2/FiO2 and PaO2/PAO2 ratio, arterial-mixed venous O2 content (AVDO2), and O2 extraction ratio (O2ER) estimation were collected on anesthesia induction, 10, 20, 30, and 40 min during AO and 10 and 20 min after reconnection to the ventilator. Concomitant hemodynamic data were obtained. RESULTS: Besides PvO2 and PAO2, AO adversely influenced PaO2 (248-113 mmHg), PaCO2 (35-145 mmHg), PvCO2, PaO2/FiO2, and PaO2/PAO2 in a time-depended fashion, whereas SvO2, AVDO2, and O2ER were minimally affected. P(a - v)CO2 was reversed throughout AO. Acid-base status derangement, consisting of HCO3a elevation, BEa widening, and acidemia (pH 6.9) maximized 40 min after AO. During AO, heart rate, systemic and pulmonary circulation pressures, and cardiac output were progressively elevated, whereas systemic vascular resistance was reduced. All the studied parameters reverted almost to baseline within the 20-min period of ventilator reconnection. CONCLUSION: Tracheal AO for 40 min ensures acceptable blood oxygenation, promotes notable hypercapnic acidosis, and consequent transient hemodynamic alterations, which are almost completely reversible after reconnection to the ventilator.

Cerebral oxygenation impairment and S-100ß protein release during off-pump coronary artery revascularization.

OBJECTIVE: To elucidate the magnitude of global cerebral oxygenation impairment, using cerebral oxygenation indices and S-100ß protein as potential markers, during off-pump coronary artery bypass grafting (OPCAB). DESIGN: Prospective cohort study. SETTING: Tertiary cardiac center. PARTICIPANTS: Thirty-five patients undergoing OPCAB. INTERVENTIONS: Jugular bulb and arterial blood samples for cerebral oxygenation indices (arterial oxygen and carbon dioxide partial pressures, jugular bulb oxygen saturation, arterial-jugular bulb oxygen content, arterial-jugular carbon dioxide partial pressure, brain oxygen extraction ratio, and estimated respiratory quotient) and S-100ß protein determination were collected at anesthesia induction; anterior, inferior, and posterior wall anastomoses; after sternal closure; and 6 hours postoperatively. Concomitant hemodynamic data were obtained. The S-100ß determination was extended to 12 and 24 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Heart positioning for the target vessel exposure induced significant hemodynamic deterioration (p < 0.001). Although cerebral oxygenation indices were influenced adversely by a low-cardiac-output state mainly during vertical heart dislocation (p < 0.001), they remained within normal limits. Hemodynamic and cerebral oxygenation statuses reverted to baseline within 6 hours postoperatively. Similarly, S-100ß jugular bulb and arterial protein levels presented a gradual increase, which peaked by the end of surgery (means, 0.54 and 0.62 µg/L, respectively; p < 0.001) and then decreased by the first postoperative day. Jugular bulb-arterial S-100ß levels were maximized during posterior wall anastomosis (0.098 µg/L; p < 0.01). CONCLUSION: Although exposure of the 3 main coronary arteries during OPCAB promotes derangement of the cerebral oxygen indices and S-100ß release, this seems to be transient, remains within the near-normal range, and is reversible almost completely 6 hours postoperatively.

Correlation of central venous-arterial and mixed venous-arterial carbon dioxide tension gradient with cardiac output during neurosurgical procedures in the sitting position.

BACKGROUND AND OBJECTIVE: The study was conducted to evaluate the correlation of central venous-arterial and mixed venous-arterial pCO(2) gradient with cardiac output in patients being operated in the sitting position. METHODS: Fifty-one patients, aged 41-69 years, classified as American Society of Anesthesiologists physical status II and III, scheduled to undergo elective neurosurgical procedures in the sitting position, were enrolled in this prospective cohort study. Simultaneous blood gas samples from arterial, central venous and pulmonary artery catheters were collected at four different time points during supine and sitting position. Cardiac index (CI) determination was accomplished simultaneously, with continuous cardiac output technique. The mixed venous-arterial pCO(2) and central venous-arterial pCO(2) gradients were calculated and related to CI at the specific time points, thus a total of 204 points of comparison were obtained. RESULTS: Changing from the supine to the sitting position induced a significant deterioration of CI, right atrial pressure, mean pulmonary arterial pressure and pulmonary wedge pressure. The mean delta pCO(2) difference (bias) in the four time points ranged between -0.07 and -0.27. The upper (1.59-1.71 mmHg) and lower limits of agreement (-2.16 to -1.82 mmHg) were quite narrow, suggesting an acceptable overall agreement between the mixed and central venous pCO(2) differences. The coefficient of determination (R(2)) between the venous-arterial pCO(2) and CI for mixed and central venous circulations was 0.830 and 0.760 (P < 0.001 for both), respectively. In contrast, R(2) values between mixed and central venous oxygen saturation values and CI were 0.324 and 0.286, respectively (P < 0.001 for both), illustrating a rather weak relationship. CONCLUSION: It seems that venous-arterial pCO(2) values obtained from mixed and central venous circulations can be reliably interchanged in estimating CI in patients undergoing neurosurgical procedures in the sitting position. Thus, central venous-arterial pCO(2) gradient could serve as a useful and simple method for estimating cardiac performance, in which further invasive monitoring is not strongly indicated.

Unexpected complication of massive intraoperative pulmonary embolism following elective sigmoidectomy in the supine position.

We describe a case of massive intraoperative pulmonary thromboembolism during elective sigmoidectomy in the supine position. During recovery from anesthesia, the patient developed hemodynamic compromise and severe hypoxemia. Intravenous inotropes and mechanical ventilation were instituted. The abrupt onset of symptoms and the pulmonary artery catheter, chest radiograph, and transesophageal echocardiography findings suggested massive pulmonary thromboembolism as a possible cause of the hemodynamic compromise and hypoxemia. Emergent angiography could not be carried out due to the patient's poor clinical status. Lack of experience in performing embolectomy, along with contraindication for thrombolysis, imposed the use of intravenous heparin and hemodynamic support as the only appropriate therapeutic modality. After 2 days' aggressive hemodynamic and ventilatory support, the patient had an uneventful course, and was discharged from the intensive care unit (ICU) 14 days later.