Head-down Position Research Articles

Influence of different tilt positions for laparoscopic hysterectomy on intraocular pressure and postoperative comfort of patients

Objective To observe the influence of different tilt positions for laparoscopic hysterectomy on intraocular pressure and patients’ postoperative comfort. Methods Totals of 80 patients with laparoscopic surgery with grade-I anesthesia (American Society of Anesthesiologists, ASA) were chosen and divided into group A(15°T) and group B (30°T) by using the random table methods, with 40 cases in each. Intraocular pressure of patients at baseline (T0), 30 minutes (T1) and 60 minutes (T2) of pneumoperitoneum and after changing the position, and 10 minutes after pneumoperitoneum were monitored. The follow-up of the patients was within 24 hours asking the comfort of them. Results The intraocular pressure of patients at T1 and T2 in group A were (18.16±2.16) and (19.60±2.18)mmHg, which were significantly lower than group B [(19.21±2.17) and (20.87±2.17)mmHg] (t=2.168 9, 2.611 3, respectively; P 0.05). Conclusions 15°head-down position laparoscopic surgery has less effect on the patient’s intraocular pressure than 30°head-down position laparoscopic surgery, besides, patients have more comfort. Key words: Head-down tilt; Laparoscopes; Hysteretomy; Intraocular pressure; Inclination; Comfort

Optic nerve sheath diameter remains constant during robot assisted laparoscopic radical prostatectomy.

BackgroundDuring 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.MethodsAfter 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).ResultsThe 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.ConclusionEven 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.

Changes in endotracheal tube cuff pressure during laparoscopic surgery in head-up or head-down position.

BackgroundThe abdominal insufflation and surgical positioning in the laparoscopic surgery have been reported to result in an increase of airway pressure. However, associated effects on changes of endotracheal tube cuff pressure are not well established.Methods70 patients undergoing elective laparoscopic colorectal tumor resection (head-down position, n = 38) and laparoscopic cholecystecomy (head-up position, n = 32) were enrolled and were compared to 15 patients undergoing elective open abdominal surgery. Changes of cuff and airway pressures before and after abdominal insufflation in supine position and after head-down or head-up positioning were analysed and compared.ResultsThere was no significant cuff and airway pressure changes during the first fifteen minutes in open abdominal surgery. After insufflation, the cuff pressure increased from 26 ± 3 to 32 ± 6 and 27 ± 3 to 33 ± 5 cmH2O in patients receiving laparoscopic cholecystecomy and laparoscopic colorectal tumor resection respectively (both p < 0.001). The head-down tilt further increased cuff pressure from 33 ± 5 to 35 ± 5 cmH2O (p < 0.001). There six patients undergoing colorectal tumor resection (18.8%) and eight patients undergoing cholecystecomy (21.1%) had a total increase of cuff pressure more than 10 cm H2O (18.8%). There was no significant correlation between increase of cuff pressure and either the patient's body mass index or the common range of intra-abdominal pressure (10-15 mmHg) used in laparoscopic surgery.ConclusionsAn increase of endotracheal tube cuff pressure may occur during laparoscopic surgery especially in the head-down position.

Current national recommendations on rapid sequence induction in Europe. How standardised is the 'standard of care'?

When inducing general anaesthesia, protective reflexes of the airways diminish and finally fail – non-fasting or predisposed patients are then at risk of aspiration. Aspiration of gastric content can cause severe lung tissue damage, oxygenation disturbances and even acute respiratory distress syndrome, known after the first describer as Mendelson’s syndrome. Failure to secure the patients’ airway is a major contributor to an adverse outcome. Rapid sequence induction (RSI) is generally accepted as the technique of choice for securing the airway in patients at risk for aspiration. Such risks include conditions that predispose (e.g. gastroesophageal reflux disease), are illness-specific (e.g. ileus) or situational (e.g. non-fasting patient in an emergency). Although the concept of RSI is generally approved, the technique itself is not standardised at all. Many drugs may be used and are recommended in literature, including any combination of different hypnotics, opioids and muscle relaxants. Furthermore, several different techniques can be used, such as cricoid pressure, head-up or head-down position, extensive oxygenation prior to inductionof anaesthesia or semi-rigid stylets in the tracheal tube. In Germany, the scientific working group ‘paediatric anaesthesia’, a subgroup of specialists from the German Society of Anaesthesiology and Intensive Care (DGAI), has published a detailed recommendation on RSI for children. However, for adult patients, no recommendations have been published in our country. The aim of our study was to evaluate the situation of current recommendations for RSI in all European countries.

Nitroglycerine and patient position effect on central, hepatic and portal venous pressures during liver surgery.

To reduce blood loss during liver surgery, a low central venous pressure (CVP) is recommended. Nitroglycerine (NG) with its rapid onset and offset can be used to reduce CVP. In this study, the effect of NG on portal and hepatic venous pressures (PVP and HVP) in different body positions was assessed. Thirteen patients undergoing liver resection were studied. Cardiac output (CO), mean arterial pressure (MAP) and CVP were measured. PVP and HVP were measured using tip manometer catheters at baseline (BL) in horizontal position; during NG infusion, targeting a MAP of 60 mmHg, with NG infusion and the patient placed in 10 head-down position. NG infusion reduced HVP from 9.7 ± 2.4 to 7.2 ± 2.4, PVP from 12.3 ± 2.2 to 9.7 ± 3.0 and CVP from 9.8 ± 1.9 to 7.2 ± 2.1 mmHg at BL. Head-down tilt during ongoing NG resulted in increases in HVP to 8.2 ± 2.1, PVP to 10.7 ± 3 and CVP to 11 ± 1.9 mmHg. CO at BL was 6.3 ± 1.1, which was reduced by NG to 5.8 ± 1.2. Head-down tilt together with NG infusion restored CO to 6.3 ± 1.0 l/min. NG infusion leads to parallel reductions in CVP, HVP and PVP at horizontal body position. Thus, CVP can be used to guide NG dosage and fluid administration at horizontal position. NG infusion can be used to reduce HVP. Head-down tilt can be used during NG infusion to improve both blood pressure and CO without substantial increase in liver venous pressure. In head-down tilt, CVP dissociates from HVP and PVP.

Design, development and evaluation of an inflatable retractor for atraumatic retraction in laparoscopic colectomy.

Laparoscopic colectomy is the gold standard in the treatment of malignant tumours arising in the mucosa of the colon wall. The procedure is performed under general endotracheal anaesthesia and involves establishing a pneumoperitoneum with the patient in the Trendelenburg position. However this position can cause anaesthetic difficulties due to excess blood flow to the head and neck, increased pressure on the diaphragm and increased venous pressure. In the absence of steep head-down positioning, the bowels fall or "spill" into the operating field, obstructing the surgical space. The primary goal of this work is to design an atraumatic laparoscopic retractor to minimise the Trendelenburg position whilst effectively retracting the bowels from the operating field. This work details the design, evaluation and optimisation of a novel, hand held, inflatable, laparoscopic retractor, through physical experimentation, computer simulation, and pre-clinical animal investigation. The optimised design for the inflatable retractor performs in line with simulated expectations, and was successfully tested for safety and technical feasibility in vivo in a porcine model, where the bowels were effectively removed from the operating space whilst the model remained in the supine position. These initial results represent a promising approach for the mitigation of the Trendelenburg position, whilst effectively retracting the bowels during laparoscopic colectomy, using this atraumatic, inflatable retractor.

Posture-induced changes of ocular vestibular evoked myogenic potentials suggest a modulation by intracranial pressure

Ocular vestibular evoked myogenic potentials (oVEMPs) represent extraocular muscle activity in response to vestibular stimulation. We sought to investigate whether oVEMPs are modulated by increasing intracranial pressure (ICP). Air-conducted oVEMPs were elicited in 20 healthy subjects lying supine on a tilt table. In order to elevate the ICP, the table was stepwise tilted from the horizontal plane to a 30° declination, corresponding to a 0°, 10°, 20° and 30° head-down position. At each inclination angle, oVEMP recording was performed in two head positions: (1) the head in line with the body and (2) the head positioned horizontally with the body tilted. When tilting both the body and head, oVEMP amplitudes gradually declined from 4.59 μV at 0° to 2.24 μV at 30° head-down position, revealing a highly significant reduction in amplitudes for all tilt angles when compared to the baseline value (p < 0.001). In parallel, the response prevalence decreased and latencies prolonged. Similar effects were observed when the body was tilted but the head positioned horizontally, even though the decrease in oVEMP amplitudes was less pronounced. A gravitoinertial force effect upon the otolith organs could thereby be excluded as a possible confounder. Hence, oVEMPs were most likely modulated by increasing ICP. In the range of the horizontal plane to a 30° head-down tilt, there was a linear correlation between oVEMP amplitudes and the inclination angle. oVEMPs might in principle be suited for non-invasive ICP monitoring.

Muscle injury following laparoscopic appendectomy

To the Editor: We describe a rare case of position-related muscle injury in a previously healthy 13-year-old boy (height 155 cm; weight 45 kg) undergoing laparoscopic appendectomy. The surgery was performed in supine position with the patient under general anesthesia and thoracic epidural analgesia. Duration of the laparoscopic procedure was 78 min. Patient positioning was in a head-down position as great as 30 . We carefully monitored the patient’s position to avoid compressing his body. After emerging from anesthesia, he did not complain of surgical site pain or hip pain. However, he complained of severe left hip pain after 6 h. The hip appeared to be swollen and tender. On postoperative day 3, magnetic resonance imaging did not indicate other serious diseases, such as necrotizing fasciitis or rhabdomyolysis (Supplementary Fig. 1). The muscle pain was improved by conservative therapy. Despite full-scale preparations for minimizing risk, position-related muscle injury occurred in a healthy pediatric patient. When a patient is in the head-down position, maintenance of limb perfusion is important to avoid position-related soft tissue injury [1]. Estimating from a simple model in a head-down position of 30 (Supplementary Fig. 2), blood pressure around the hip drops about 1/5.44 9 (height, cm) mmHg compared to that of the head. In pediatric cases, this pressure gradient could have a bad influence on limb perfusion because the normal blood pressure in children is lower than in adults. Additional intermittent measurement of blood pressure at the lower extremity could be effective for monitoring limb perfusion. If blood pressure in the lower extremity cannot be maintained, the anesthesiologist should consider intermittent reversal of the head-down position or limiting the duration of that position.

Effect of postural changes on normal and stenosed common carotid artery using FSI

Gravity associated with postural changes has a strong bearing on haemodynamics of blood flow in arteries. Its effect on stenosed cases has not been widely investigated. In the present study, variation observed in blood flow during postural changes is investigated for different conditions like standing, sleeping and head-down position. A fluid structure interaction study is carried out for idealized normal and 75% eccentric and concentric stenosed common carotid normal artery. The results clearly indicate the effects of altered gravity on flow conditions. It was found to be very significant during head-down position and demonstrated very high arterial blood pressure in stenosed common carotid when compared with normal carotid.

Marked olfactory impairment in idiopathic intracranial hypertension

ObjectiveMany long-duration astronauts develop signs of elevated intracranial pressure and have neuro-ophthalmological findings similar to idiopathic intracranial hypertension (IIH) patients. Some also present with nasal congestion and subjective olfactory impairment....

Minimal impairment in pulmonary function following laparoscopic surgery

Pulmonary function may be impaired in connection with laparoscopic surgery, especially in the head-down body position, but the clinical importance has not been assessed in detail. The aim of this study was to assess pulmonary function after laparoscopic hysterectomy and laparoscopic cholecystectomy. We hypothesised that arterial oxygenation would be more impaired after hysterectomy performed in the head-down position than after cholecystectomy in the head-up position. We included 60 women in this prospective, observational study. The patients underwent elective laparoscopic cholecystectomy in the 20° head-up position or hysterectomy in the 30° head-down position. The primary outcome was the difference between arterial oxygenation (PaO2 ) 2 h postoperatively and the preoperative value. Two hours and 24 h after surgery, pulmonary shunt and ventilation-perfusion mismatch were assessed by use of an automatic lung parameter estimation system. Two hours after surgery, the mean change from baseline in PaO2 was -0.65 kPa [95% confidence interval (CI) -3.5 to 3.4, P = 0.14] in the hysterectomy group and -0.22 kPa [95% CI -3.4 to 2.0, P = 0.12] in the cholecystectomy group (P = 0.88). Shunt was significantly greater in the cholecystectomy group 24 h after surgery compared to the hysterectomy group [4%, 95% CI 0 to 9 vs. 0%, 95% CI 0 to 7, P = 0.02]. Minimal impairment in pulmonary gas exchange was found after laparoscopic surgery. Pulmonary shunt was larger after laparoscopic cholecystectomy, but no clinically significant differences in postoperative pulmonary gas exchange or spirometry were found between laparoscopic hysterectomy and laparoscopic cholecystectomy.

Upside-down death - the pathophysiology of inversion

Historically, deaths occurring in a head-down position were generally associated with inverted suspension inflicted upon the victim as a form of torture. In the current day, deaths occurring due to an inverted body position are rare and are usually the result of freak accidents which often attract media attention due to the unusual nature of the death. Occasionally an element of inverted suspension is present in deaths occurring in motor vehicle incidents when the vehicle rolls, coming to rest on its roof with the unconscious victim left suspended upside-down by the seat belt. Human physiology has evolved to work in combination with gravity and the effects of hanging upside down for prolonged periods are poorly understood. I will review deaths associated with the head-down position and the underlying pathophysiology of inversion leading to death.

Venous air embolism during vitrectomy: a rare but potentially fatal complication.

Over 4,000 articles have been published on intraoperative venous air embolism (VAE) since it was first described in the 19th century [1]. Although its pathological mechanisms, preventative measures, and treatment methods have been established, it still appears consistently. VAE occurs when the pressure in an open vein is lower than atmospheric pressure. Thus, it is caused when a wound is at a higher level than the heart. The pathophysiological consequences of VAE depend on the velocity and quantity of air entry. Air bubbles flowing into the venous system lodge in the pulmonary circulation and are then diffused to alveoli to be exhaled during expiration. In most patients, a small quantity of air bubbles is tolerable. However, if the amount of air exceeds the pulmonary clearance capacity, increasing pulmonary artery pressure and, thus, increased right ventricular afterload, which may cause cardiac arrest. In particular, in patients with patent foramen ovale, paradoxical air embolism can result in a stroke or coronary occlusion, which may be fatal. General management of VAE includes notifying the operating surgeon, procedure discontinuance, use of 100% oxygen, aspiration of entrained air through a central venous catheter, aggressive intravascular volume infusion, use of a vasopressor, bilateral jugular vein compression, placing the patient in a headdown position and, if necessary, cardiac pulmonary resuscitation (CPR). It is known that VAE occurs most commonly during sitting craniotomy [1]. However, suitable conditions for it can occur whenever a wound is above the level of the heart. In this issue of the Korean Journal of Anesthesiology, Shin et al. [2] report VAE occurring during vitrectomy with airfluid exchange. One patient who was under mechanical ventilation with an oxygen/air mixture suddenly showed findings of cardiac arrest after starting air-fluid exchange. Although the surgical procedure was stopped quickly and CPR was performed, vital signs did not recover and thus percutaneous cardiopulmonary support was applied. Postoperative transesophageal echocardiogram revealed a patent foramen ovale. VAE can occur during various surgical procedures [1] but it is rare in ophthalmic surgery. The first case report was published by anesthesiologists in 2005 [3] and it was then first introduced in an ophthalmology journal in 2010 [4]. In sitting craniotomy, where the incidence of VAE is among the highest, neurosurgeons are well aware of VAE but ophthalmic operating surgeons tend not to be. Highlighting this, an interesting study was recently conducted by ophthalmologists [5]. Four donor eyes unsuitable for tissue donation were used for simulated vitrectomies. This experiment was performed with 23- or 25-gauge cannulas under several intraocular pressures (30-60 mmHg). They measured air flow against atmospheric pressure to be ~350 ml/min under 40 mmHg infusion pressure through a 25-gauge line. Considering that an air volume of 200 ml (35 ml/kg) may be fatal [1], both ophthalmologists and anesthetists should be aware that ocular air fluid exchange is not completely safe and may even be fatal, especially for patients with patent foramen ovale. Fortunately, not all air bubbles flowing in the venous system during vitrectomy surgery are potentially fatal. However, like the case described in this issue of the Korean Journal of Anesthesiology, complications in patients with other risk factors may be fatal. Thus, continuous preoperative and intraoperative attention by operating surgeons and anesthetists is required to prevent it.

Positional Asphyxia without Active Restraint Following an Assault

Deaths due to positional asphyxia are most often accidental, associated with alcohol and/or drug intoxication. A 19-year-old male is reported who was assaulted and placed in a head-down position in the back of a car were he was later found dead. Brush abrasions indicated that he had been dragged to the vehicle. The head and right shoulder were wedged into the foot well with the body uppermost. At autopsy, there was marked congestion of the face, neck, and upper chest with conjunctival ecchymoses, bruising of the face and scalp, focal subarachnoid hemorrhage, minor cerebral contusion, and diffuse cerebral swelling with early hypoxic ischemic encephalopathy (HIE). Toxicology was negative. Death was attributed to HIE resulting from the unusual positioning of the body. Cases of positional asphyxia involving others may not always include restraint, and when encountered should initiate a careful evaluation of the possible events and lethal pathophysiological processes.

Photoplethysmogram change by Trendelenburg position and insufflation of abdominal carbon dioxide

To the Editor: Laparoscopic surgery has an inherent risk of complications because of increased abdominal pressure (IAP) and intra-abdominal carbon dioxide inflation [1]. We report a case where venous pulsation was detected in finger photoplethysmogram (PPG) during laparoscopic surgery in the head-down position (HDP). A 32-year-old woman (height 160 cm, weight 64 kg) was scheduled for laparoscopic right ovarian cystectomy. Preoperatively, she had no significant medical history except for a previous caesarian section. Before induction of anesthesia, the blood pressure was 125/74 mmHg and the heart rate was 90/min. The patient’s status was monitored by routine protocols. The PPG probe (DS 100A; Nellcor, Pleasanton, CA) was placed on the right index finger and connected to a patient monitor (Solar 8000M; GE Medical System, Milwaukee, WI). PPG data were stored via a 12-bit analog-digital converter (EZAD-512; ELBIO, Seoul, Korea) at a rate of 100 Hz. After induction of anesthesia, the patient was placed in the lithotomy position with the right arm abducted at 90 and the left arm attached to the side of body. Initial PPG was normal (Fig. 1a) and pulse oximetry values (SpO2) were 99 %. After carbon dioxide was insufflated at a pressure of 12 cmH2O, the operating table was tilted to 30 in the HDP. The SpO2 was 95 % and the waveform of PPG showed unexpected peaks and high amplitude (Fig. 1b). Arterial blood pressure changes were within 20 mmHg during the position change. When the PPG probe was moved to the patient’s other finger, the same SpO2 and PPG were observed. However, when the PPG probe was placed on a finger of one of the authors, normal PPG was obtained, thereby confirming that the PPG probe was functioning well. A tourniquet (tourniquet 4500; VBM, Sulz, Germany) was applied to the right upper arm at a pressure of 20, 30, 40, and 50 mmHg to confirm the venous origin of the abnormal waveform (Fig. 1c) [2], with subsequent increase in the SpO2 to 97 %. The amplitude of abnormal peaks in PPG was slightly reduced when abdominal CO2 was deflated in the HDP, but its waveform was still different from that of normal PPG (SpO2 96 %). Normal SpO2 (99 %) and PPG similar to that in Fig. 1a were displayed when the patient was placed in the supine position without tourniquet application. It is possible that the pressure of the tourniquet could block the venous effect resulted from mild tricuspid regurgitation (around 20 mmHg), HDP (around 20 mmHg), and IAP (12 mmHg). The implication of this case report is that venous pulsation in PPG could be induced by IAP and HDP. The possible mechanism is that mild tricuspid regurgitation aggravated by HDP may cause a high degree of variability in the PPG. In this case, HDP significantly contributed to the formation of venous pulsation in PPG; however, IAP J.-H. Bahk W. Ahn (&) Department of Anesthesiology and Pain Medicine, Seoul National University Dental Hospital, 103 Daehangno Jongno-gu, Seoul 110-768, Republic of Korea e-mail: aws@snu.ac.kr

Prolonged steep Trendelenburg position: risk of postoperative upper airway obstruction

Robot-assisted laparoscopic radical prostatectomy (RALRP) is the procedure of choice for the surgical treatment of prostatic cancer. Following induction of anesthesia, the patient is placed in a steep Trendelenburg position (40 – 45 ) in combination with a CO2 pneumoperitoneum. The steep Trendelenburg position is required for an optimal surgical exposure and to utilize the technical advantages of the robot. Besides the physiological effect of this position on the cardiovascular, respiratory and central nervous system, complications such as brachial plexus injuries, corneal abrasions and ischemic optic neuropathy have also been reported [1]. In our experience with RALRP over the last 8 years, upper airway obstruction in the postoperative period is another complication of RALRP which has not been widely reported. Some patients develop an obstructed breathing pattern after extubation associated with agitation and sometimes desaturation despite an adequate reversal of neuromuscular blockade. This is more common in patients who have had prolonged head-down position of more than 3 h or over-enthusiastic fluid therapy exceeding 3 L. Patients who have a large neck circumference or suffer from chronic obstructive airway disease (COPD) are also more prone to develop a similar obstruction. Although there is a report of laryngeal edema following RALRP [2], none of our patients has developed laryngeal edema. The upper airway obstruction usually resolves either with the insertion of a nasopharyngeal airway or with the application of continuous positive airway pressure. In the postanaesthesia care unit, these patients are then nursed in a head-up position and the symptoms resolve in 1–2 h. It has been reported that, in the 45 Trendelenburg position, central venous pressure increases almost threefold compared with the initial value [3]. The head-down position along with pneumoperitoneum also increases the abdominal pressure, which impedes the venous return from the head and neck. This increase in the capillary hydrostatic pressure leads to interstitial accumulation of fluid in the dependent tissues. This is most apparent in the form of periorbital and conjunctival edema. However, edema also forms in the neck and peripharyngeal tissues, which causes constriction of the upper airway lumen. Chiu et al. [4] showed that displacement of a small amount of fluid (340 ml) from the legs is sufficient to cause a 102 % increase in pharyngeal resistance in healthy, non-obese subjects. The degree of fluid accumulation is often directly proportional to the amount of fluid transfused and the length of the surgery. This theory is also corroborated by the fact that fluid overload in fluid-retension states such as heart and renal failure is responsible for the increased incidence of obstructive sleep apnea in these patients [4]. The effect of dependent edema in the upper airway would logically be exaggerated in obese patients with increased neck circumference who already have a compromised upper airway lumen due to fat deposition. In patients with COPD, it has been postulated that cigarette smoking may affect the upper-airway dilator muscles or that treatment with inhaled corticosteroids may cause local pharyngeal muscle myopathy which could lead to obstructive sleep apnea [5]. Therefore, a small amount of edema formation in the upper airway in these patients would make them V. Rewari (&) R. Ramachandran Department of Anaesthesiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India e-mail: vimirewari@gmail.com; vimirewari@hotmail.com

Cerebral blood flow is governed by the capillary pumps driven by electricity of neurons and their heat and CO2 production. Hammock posture is the optimal one

to the editor: We applaud Dr. Zuj and colleagues ([5][1]) for their study describing the relative contribution of arterial CO2 partial pressure (PaCO2) and brain level arterial pressure (BPMCA) for the syncope, prior- and post-head-down bed rest (HDBR). We appreciate their conclusion that cerebral

Does Intraocular Pressure Increase During Laparoscopic Surgeries? It Depends on Anesthetic Drugs and the Surgical Position

Pneumoperitoneum in the pelvic laparoscopic surgery induces a rise in the intraocular pressure (IOP). This study investigated whether IOP changes were different depending on the surgical position (Trendelenburg vs. reverse Trendelenburg) and the anesthetic drugs (propofol vs. desflurane). : A total of 100 patients scheduled for pelvic laparoscopy or laparoscopic cholecystectomy were enrolled. They were randomly allocated into the propofol group or the desflurane group. In the desflurane group, anesthesia was given with thiopental and desflurane. The propofol group was anesthetized with propofol. IOP, mean blood pressure, heart rate, and peak airway pressure were measured at the following time points: awake-supine position, induction of anesthesia, after position change, 5, 10, and 20 minutes after pneumoperitoneum. IOP was measured with the handheld tonometer (Tono-penXL). : In all the groups, IOP decreased after anesthesia was initiated (17 ± 2 to 11 ± 2 mm Hg). In laparoscopic cholecystectomy, a low IOP was maintained during the period of pneumoperitoneum, independent of anesthetic drugs. In pelvic laparoscopy, the head-down position produced a rise in IOP (11 ± 2 to 14 ± 3 mm Hg). Further, pneumoperitoneum in addition to the head-down position raised the IOP highly in the desflurane group, and the average IOP value was over the normal limit (22 ± 4 mm Hg). In contrast, propofol kept IOP similar to the preoperative level during the whole period of pneumoperitoneum (18 ± 3 mm Hg, P<0.001 vs. desflurane). : Impact of anesthetics on IOP during laparoscopic surgery may change depending on the surgical position. For the laparoscopic surgery performed in the head-down position, propofol may be more helpful in preventing ocular hypertension.

Day/Night Variability in Blood Pressure: Influence of Posture and Physical Activity

Blood pressure (BP) is highest during the day and lowest at night. Absence of this rhythm is a predictor of cardiovascular morbidity and mortality. Contributions of changes in posture and physical activity to the 24-hour day/night rhythm in BP are not well understood. We hypothesized that postural changes and physical activity contribute substantially to the day/night rhythm in BP. Fourteen healthy, sedentary, nonobese, normotensive men (aged 19-50 years) each completed an ambulatory and a bed rest condition during which BP was measured every 30-60 minutes for 24 hours. When ambulatory, subjects followed their usual routines without restrictions to capture the "normal" condition. During bed rest, subjects were constantly confined to bed in a 6-degree head-down position; therefore posture was constant, and physical activity was minimized. Two subjects were excluded from analysis because of irregular sleep timing. The systolic and diastolic BP reduction during the sleep period was similar in ambulatory (-11±2mmHg/-8±1mmHg) and bed rest conditions (-8±3mmHg/-4±2mmHg; P = 0.38/P = 0.12). The morning surge in diastolic BP was attenuated during bed rest (P = 0.001), and there was a statistical trend for the same effect in systolic BP (P = 0.06). A substantial proportion of the 24-hour BP rhythm remained during bed rest, indicating that typical daily changes in posture and/or physical activity do not entirely explain 24-hour BP variation under normal ambulatory conditions. However, the morning BP increase was attenuated during bed rest, suggesting that the adoption of an upright posture and/or physical activity in the morning contributes to the morning BP surge.

Cardiovascular and respiratory effects of the degree of head‐down angle during robot‐assisted laparoscopic radical prostatectomy

Robot-assisted laparoscopic radical prostatectomy (RALP) requires a steep Trendelenburg position and CO2 pneumoperitoneum for several hours to secure the surgical visual field. The present study was performed to investigate the influence of each angle of Trendelenburg position during RALP on cardiovascular and respiratory homeostasis. Forty-seven ASA physical status 1 and 2 patients underwent open retropubic radical prostatectomy (RRP) or RALP. Patients receiving RALP were randomized to undergo the operation in the 20°, 25° or 30° Trendelenburg position. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), end-tidal CO2 pressure (PetCO2 ), tidal volume (Vt), peak inspiratory pressure (PIP) and dynamic compliance (Cdyn) were recorded during the operation. Angle of head-down tilt was significantly correlated with MAP, PIP and Cdyn, but not with HR, RR or PetCO2 . MAP decreased gradually over time in each group in the Trendelenburg position with pneumoperitoneum. As the angle of head-down tilt became stronger, MAP, RR, PetCO2 and PIP tended to increase and Cdyn tended to decrease. This study demonstrated that the degree of the head-down angle at RALP affected the cardiovascular and respiratory parameters. Pneumoperitoneum with head-down position in RALP influenced the cardiovascular and respiratory system to a greater extent than RRP, and these effects were stronger with deeper head-down angle.