LETTER TO THE EDITOR
Year : 2013  |  Volume : 45  |  Issue : 2  |  Page : 203-204

A comparison of hypotension and bradycardia following spinal anaesthesia in patients on calcium channel blockers and β-blockers

Amol Patil¹, Snehalata Gajbhiye¹, Shweta Salgaonkar^2
1 Department of Pharmacology, Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital, Parel, Mumbai, India
² Department of Anesthesia, Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital, Parel, Mumbai, India

Correspondence Address:
Amol Patil
Department of Pharmacology, Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital, Parel, Mumbai
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/0253-7613.108329

1. It is not clear what the control group comprised of and which medications they received. Did the control group comprise of ASA 1 normotensive patients as described in the methodology or are they the patients with essential hypertension as mentioned in inclusion criteria?
2. In the inclusion criteria, there is no mention of duration and dose of the antihypertensive medications. If we correlate it with results, there appears to be patients taking medications for less than 20 days (recently diagnosed hypertensives). The mean duration for which drug was taken in the group receiving calcium channel blockers was 579 days. Thus, there is a wide variability and will have a bearing in the conclusions drawn from the article. In the inclusion criteria an upper age limit should have been considered because age more than 50 years increases risk of hypotension 2.358 times ^.[2] Also women have greater chance of developing hypotension so they should have been equally distributed in all 3 groups. ^[2]
3. In the exclusion criteria absolute and relative contraindications of spinal anesthesia (for example allergy and hypersensitivity to local anesthetic, skin lesions at site of injection, vertebral anomalies, abnormal coagulation profile, preexisting spinal cord disorders, BMI>30kg/m ² , anaemia, chronic alcohol consumption as high risk of developing hypotension) should have been mentioned. ^[2]
4. It is not mentioned whether the drug has been given on the day of surgery.
5. Use of premedication in the patient is not specified. It is important to know if premedication (glycopyrolate, atropine, opids, benzodiazepines) was given and if it was similar in both groups.
6. Bradycardia has been defined as heart rate less than 50 beats per minute for which no reference is quoted. In how many patients the fall in HR was associated with hypotension as defined?
7. In the results section it has been stated that 15 patients in control group had a decrease in blood pressure more than 20% but they have included them as hypotensive in [Table 3]. This is against their definition in which they have defined hypotension as decrease in B. P. by more than 30%. So incidence of hypotension in control group may go down significantly which in turn may bring after the p value for incidence of hypotension in all groups.
8. A study by Dinesh et al.,^[3] which is wrongly summarized. All risk factors mentioned are associated with incidence of early hypotension following spinal anesthesia. But in the article authors have written that the risk factors mentioned are not associted with incidence of early hypotension following spinal anesthesia.
9. The findings of Sear et al.,^[4] study discussed are related to general anesthesia. This is not relevant here as this study uses spinal anesthesia.
10. The authors have concluded that better anticipation of complications could be made in frail patients when they have included ASA I-II patients in study.

» References

1.	Kaimar P, Sanji N, Upadya M, Mohammed KR. A comparison of hypotension and bradycardia following spinal anesthesia in patients on calcium channel blockers and β-blockers. Indian J Pharmacol 2012;44:193-6.   [PUBMED]
2.	Singla D. Risk factors for development of early hypotension during spinal anaesthesia. J Anaesthesiol Clin Pharmacol 2006;22:387-93.
3.	Singla D, Kathuria S, Singh A, Kaul TK, Gupta S, Mamta. Risk factors for development of early hypotension during spinal anaesthesia. J Anaesthesiol Clin Pharmacol 2006;22:387-93
4.	Sear JW, Jewkes C, Tellez JC, Foex P. Does the choice of antihypertensive therapy influence haemodynamic responses to induction, laryngoscopy and intubation? Br J Anaesth 1994;73:303-8.