Intravenous Fluid to Prevent Hypotension in Patients Undergoing Elective Colonoscopy

Hypotension during propofol sedation for colonoscopy: an exploratory analysis

BACKGROUND

Intraoperative and postoperative hypotension occur commonly and are associated with organ injury and poor outcomes. Changes in arterial blood pressure (BP) during procedural sedation are not well described.

METHODS

Individual patient data from five trials of propofol sedation for colonoscopy and a clinical database were pooled and explored with logistic and linear regression. A literature search and focused meta-analysis compared the incidence of hypotension with propofol and alternative forms of procedural sedation. Hypotensive episodes were characterised by the original authors' definitions (typically systolic BP <90 mm Hg).

RESULTS

In pooled individual patient data (n=939), 36% of procedures were associated with episodes of hypotension. Longer periods of propofol sedation and larger propofol doses were associated with longer-lasting and more-profound hypotension. Amongst 380 patients for whom individual BP measurements were available, 107 (28%) experienced systolic BP <90 mm Hg for >5 min, and in 89 (23%) the episodes exceeded 10 min. Meta-analysis of 18 RCTs identified an increased risk ratio for the development of hypotension in procedures where propofol was used compared with the use of etomidate (two studies; n=260; risk ratio [RR] 2.0 [95% confidence interval: 1.37-2.92]; P=0.0003), remimazolam (one study; n=384; RR 2.15 [1.61-2.87]; P=0.0001), midazolam (14 studies; n=2218; RR 1.46 [1.18-1.79]; P=0.0004), or all benzodiazepines (15 studies; n=2602; 1.67 [1.41-1.98]; P<0.00001). Hypotension was less likely with propofol than with dexmedetomidine (one study; n=60; RR 0.24 [0.09-0.62]; P=0.003).

CONCLUSIONS

Hypotension is common during propofol sedation for colonoscopy and of a magnitude and duration associated with harm in surgical patients.

Colonoscopy-related colonic ischemia

Colonoscopy is a risk factor for colon ischemia. The colon is susceptible to ischemia due to its minor blood flow compared to other abdominal organs; the etiology of colon ischemia after colonoscopy is multifactorial. The causative mechanisms include splanchnic circulation impairment, bowel preparation, drugs used for sedation, bowel wall ischemia due to insufflation/barotrauma, and introduction of the endoscope. Gastroenterologists must be aware of this condition and its risk factors for risk minimization, early diagnosis, and proper treatment.

Fluid administration during routine colonoscopy is not clinically significant: a randomized controlled trial

BACKGROUND

Retrospective studies have questioned the benefits of intravenous (IV) fluids during routine colonoscopies given they are performed on well patients who experience limited fluid loss, consume clear fluids up until 2 h prior and low IV volumes typically infused. This trial aims to assess the impact of IV fluid on hypotension and electrolyte changes amongst patients undergoing colonoscopy.

METHODS

Participants undergoing colonoscopies were randomized (single blinded) to IV fluid or no IV fluid. Primary outcomes were equivalence of intraoperative hypotensive episodes (>20% drop in systolic blood pressure (SBP)) and changes in serum electrolytes post procedure. Secondary outcomes included patient reported outcome measures (PROMs).

RESULTS

Of the 470 participants enrolled, 84/235 (35.7%) from the IV fluids group and 88/230 (38.3%) from the no IV fluids group experienced a hypotensive event (difference in prevalence -2.5, 95% CI -11.3, 6.3). Fourteen participants in each group required clinical intervention to provide haemodynamic support (difference in prevalence -0.1, 95% CI -4.4, 4.2). Postoperative electrolytes changes and PROMs were similar for both groups.

CONCLUSION

Whilst definitive recommendations for IV fluid use during routine colonoscopy are not possible as this trial was underpowered to show equivalence between the groups for hypotensive events, there was no clinically meaningful difference between the groups. These findings provide important data for meta-synthesis and for planning future work.

The cardiovascular effects of crystalloid administration in endoscopy patients

Intravenous fluids are commonly administered for patients having colonoscopy despite relatively little data to support this practice. It is unclear what, if any, effect crystalloid administration has on stroke volume and cardiac output in patients who are fasting and have had bowel preparation agents. We aimed to assess the physiological effect of 10 ml/kg of crystalloid administration in colonoscopy patients on haemodynamic parameters including stroke volume, stroke volume variation and cardiac output, as measured with transthoracic echocardiography. Our secondary aims were to determine whether stroke volume variation predicted fluid responsiveness in gastrointestinal endoscopy patients and whether these haemodynamic measures are different in fasting patients with bowel preparation (colonoscopy patients) compared to fasting patients alone (gastroscopy patients). We recruited 54 patients having elective gastrointestinal endoscopy (25 colonoscopy, 29 gastroscopy). All patients had stroke volume, cardiac output and stroke volume variation measured with transthoracic echocardiography at baseline. In colonoscopy patients, stroke volume, cardiac output and stroke volume variation were remeasured after 10 ml/kg of intravenous crystalloid. Administration of 10 ml/kg of crystalloid increases stroke volume by 19.6 ml ( p < 0.00005) and cardiac output by 0.81 l/min ( p < 0.001). Stroke volume variation reduced from 23% to 14% after fluid administration ( p < 0.0011). The optimum threshold of stroke volume variation to predict fluid responsiveness was 21% with a sensitivity of 77.8% and specificity of 62.5%. Administration of 10 ml/kg of crystalloid increases stroke volume and cardiac output, and reduces stroke volume variation in fasting elective colonoscopy patients.

A randomized-controlled trial of high- or low-volume intravenous Plasma-Lyte(®) to prevent hypotension during sedation for colonoscopy

PURPOSE

The purpose of this study was to compare the incidence of hypotension during sedation in adults presenting for elective colonoscopy and randomized to intravenous Plasma-Lyte 148(®) at either 2 mL·kg(-1) (low volume) or 20 mL·kg(-1) (high volume).

METHODS

Patients aged ≥ 18 yr presenting for elective colonoscopy, with or without gastroscopy, after oral bowel preparation were randomized to receive the intervention immediately before the start of the procedure. Hypotension was defined as a ≥ 25% decrease in systolic blood pressure (SBP) from baseline during the procedure. Secondary outcomes included SBP < 90 mmHg, lowest SBP during sedation, duration of hypotension, use of vasopressors, postoperative outcomes, and cost.

RESULTS

Seventy-five patients were randomly allocated to either the low-volume or high-volume group, respectively (total n = 150). The incidence of hypotension was similar in the two groups (59% vs 56%, respectively; odds ratio, 0.90; 95% confidence interval, 0.47 to 1.71; P = 0.74). The incidence of SBP < 90 mmHg, the lowest SBP during sedation, the duration of hypotension, the use of vasopressors, and postoperative outcomes were also similar in the two groups.

CONCLUSIONS

This study does not support the routine use of 20 mL·kg(-1) of intravenous Plasma-Lyte 148 to prevent hypotension and other complications during sedation for elective colonoscopy in adult patients. Clinical Trials Registry (ANZCTR 12615001288516).

Fluid prescription practices of anesthesiologists managing patients undergoing elective colonoscopy: an observational study

Background

Routine fluid prescription is common practice amongst anesthesiologists caring for patients undergoing colonoscopy. However there is limited information about routine procedural fluid prescription practices of anesthesiologists in this setting. Routine fluid administration may also have important pharmaco-economic implications for the health care budget. Therefore we performed a prospective observational study assessing the fluid prescription practices of anesthesiologists caring for patients undergoing elective colonoscopy.

Methods

With Institutional Review Board approval, adult patients receiving procedural fluid intervention during elective colonoscopy were included. Data collected: size of intravenous cannula inserted, volumes of fluid administered, adverse events, procedure duration, and pharmaco-economic costs associated with fluid prescription. Anesthesiologists and gastroenterologists were blinded to the study.

Results

We collected data on 289 patients who received fluid prescription by their attending anesthesiologist. Median patient age: 48 yrs (range 18–83), gender: 174 (60%) female; median duration of procedure: 24 minutes (range 12–48). Cannula size: 181 (63%) patients received a 22G cannula or smaller. Median volume of fluid administered during the colonoscopy was 325 ml (range 0 to 1000 ml). Median duration of the procedure: 25 minutes (range 12 to 48 minutes). Median volume of fluid administered in the post anaesthesia recovery unit: 450 ml (range 0 to 1000 ml). Fifteen patients (5%) became hypotensive during the procedure and two patients (<1%) developed hypotension in the PACU. There was no difference in the median fluid requirements between patients with hypotension and those without. Fluid volumes were strongly associated with increasing cannula diameter (p = 0.0001), however there was no association between fluid volumes administered and vasopressor use, peri-procedural adverse events, or procedure duration. At our institution fluid therapy currently cost about AUD$4.90 per patient: 1 L crystalloid $1.18 and fluid delivery set $3.77 Our institution performs over 9000 endoscopic procedures annually with fluid therapy costing about $45,000/year.

Conclusions

Routine fluid prescription by anesthesiologists managing patients undergoing colonoscopy was ineffective with low actual fluid volumes delivered during the procedure. There was no association between volumes of fluid delivered and procedural hypotension, adverse events, or procedure duration. Anesthesiologists should question the clinical and pharmaco-economic value of routine fluid administration for patients undergoing elective endoscopy.

Prospective description of coughing, hemodynamic changes, and oxygen desaturation during endoscopic sedation

BACKGROUND

Deep sedation is increasingly used for endoscopy. The impact of sedation level on hemodynamic status, oxygenation, and aspiration risk is incompletely described.

AIMS

To describe the incidence of intraprocedural cough, hemodynamic changes, oxygen desaturation, and their relationship to clinical factors and sedation level.

METHODS

Detailed prospective recordings of hemodynamic changes, oxygen desaturation, and cough during 757 nonemergent endoscopic procedures done under sedation using propofol, midazolam, and/or fentanyl.

RESULTS

Thirteen percent of patients had at least one cough and 3% had prolonged cough. Cough was more common in nonsmokers (P = 0.05), upper endoscopy (P < 0.0001), with propofol (P = 0.0008), longer procedures (P = 0.0001), and hiccups (P = 0.01). The association between supine positioning during colonoscopy and cough approached significance (P = 0.06). Oxygen desaturation was rare (4%) and associated only with deep sedation (P = 0.02). Mean systolic and diastolic blood pressure (BP) dropped by 7.3 and 5.6% respectively. Decreases in systolic BP were more common in whites (P = 0.03), males (P = 0.004), nonsmokers (P = 0.04), during colonoscopy (P < 0.0001), and in patients receiving midazolam and fentanyl (P = 0.01). Heart rate (HR) dropped >20% from baseline in 15% of patients and was more common during colonoscopy (P = 0.002). HR increased >20% in 20% of patients and was more common with coughing (P < 0.0001) and in younger patients (P = 0.0002). No patient required pharmacologic treatment of BP or HR.

CONCLUSIONS

We have described procedural predictors of cough that may help clinicians reduce the risk of aspiration during endoscopy. Hemodynamic changes during endoscopy are common but largely clinically insignificant.

Adverse physiological events under anaesthesia and sedation: a pilot audit of electronic patient records

Review of perioperative activity including adverse events, throughput and compliance with 'best practice', can theoretically be used to optimise healthcare delivery. Computer-based analysis of electronic patient records could provide a practical means to manage quality improvement. This pilot study examined the effectiveness of such a system in practice. All intraoperative patient notes and physiological data were collected over 17 months in a rural hospital using data from an electronic record-keeping system. Algorithms were developed to automatically identify potential adverse events based on physiological measures. Each computer-identified event was reviewed by a panel of three anaesthetists and assessed for validity, severity and probable cause. Two areas were identified to pilot quality improvement activities-sedation for colonoscopies and inhalational anaesthesia with desflurane. Specific 'in-house' guidelines were created for these procedures and feedback on the patterns of adverse events were provided to anaesthetic staff A total of 138 separate adverse events were identified for all operative cases over 17 months, with an overall adverse event incidence of 3.3%. The adverse event incidence during colonoscopy and laryngospasm/hypoxia during desflurane anaesthesia was 6.3% and 1.3% respectively. This decreased to 2.8% (P <0.005) and 0.13% (P <0.0001) respectively for the nine months following feedback and the introduction of guidelines. Anaesthesia information systems can be an effective quality improvement tool and may enhance existing tools such as incident reporting systems.

Australian Anaesthetists’ Practice of Sedation for Gastrointestinal Endoscopy in Adult Patients

A wide spectrum of practice in sedation for gastrointestinal endoscopy in adult patients is documented overseas, but a current profile of the practice of Australian anaesthetists is unavailable. We therefore surveyed 200 Fellows of the Australian and New Zealand College of Anaesthetists on the choice of drugs and monitoring, use of analgesic throat spray and prophylactic intravenous fluids and the depth of sedation for gastrointestinal endoscopy. Our response rate was 57% and endoscopy formed a significant part of most respondents’ practices. Propofol was used for almost all procedures, in combination with midazolam alone (14%), fentanyl alone (6%), midazolam and fentanyl (61%), another drug (15%) or no adjuvant(4%). The majority of patients received prophylactic intravenous fluids for endoscopic retrograde cholangio-pancreatography (83%) and colonoscopy (64%), but not for gastroscopy (20%). All patients received supplemental oxygen and monitoring with pulse oximetry. However, over 20% of patients having gastroscopy or colonoscopy did not have noninvasive blood pressure monitoring. A maximum depth of sedation during which the patient was unresponsive to painful stimulation (commensurate with general anaesthesia) was targeted by 54% of respondents. Significant variations exist in the practice of sedation and monitoring for endoscopy in adult patients by anaesthetists in Australia.

Sedation for gastrointestinal endoscopy: the changing landscape

PURPOSE OF REVIEW

Most patients require sedation for gastrointestinal endoscopy. Moderate sedation for these procedures has traditionally been provided by the endoscopist with benzodiazepine and/or a narcotic. As endoscopy has increased in numbers and complexity, however, more effective sedation and analgesia is frequently required. Controversy has ensued over safe and efficient sedation practice. This review seeks to delineate what has been learned about this topic in the recent literature.

RECENT FINDINGS

There has been an increase both in the number of endoscopic procedures performed and in the use of propofol for endoscopic sedation. Studies have focused on several basic issues: alternatives to anesthesiologist-supervised propofol, other sedation regimens, and complications related to sedation.

SUMMARY

Alternatives to anesthesiologist-supervised propofol include nurse-administered propofol sedation supervised by the endoscopist, and patient controlled sedation. While other sedative regimens continue to be examined, the use of propofol for gastrointestinal endoscopy will continue to increase. Structured nurse-administered propofol programs appear to be safe, but the occurrence of severe respiratory depression and the ability to rescue remain concerns. Further study into appropriate sedation training, patient selection, ability to rescue, complications and value of anesthesiologist-directed sedation is necessary.